Functional connections between the pineal gland and immune system

7/28/2019 Functional connections between the pineal gland and immune system

1/17

Functional connections betweenthe pineal gland and immunesystemKrystyna Skwarto-SontaDepartm ent of Vertebrate Physiolog y, Zoological Institute, Universityof Warsaw, 93 ~ w i r k i Wigury St., 02-089 W arsaw, Poland

Abstract. Experim ental findings which support a functionalconnection between the pineal gland and immune system in mamm alsand birds are summ arized. Developm ental and age-related changes inpineal gland fun ction appe ar, at least partially, to be related w ithimmune system efficiency. Mechanisms whereby m elatonin influencesimm une system function are complex, but include participation ofmed iators (endogenou s opioids, cytokines, hormones, zinc pool) aswell as specific binding sites on the imm une cells. Melatonin, as ahighly lypophilic com pound, may also penetrate im mun e cells withoutmediation of specific receptors and act w ithin as a potent free radicalscavenger and as an anti-aging and oncostatic factor. The imm unesystem may, in turn, via synthesis a nd secretion of so luble factors,cytokines, influence pineal gland fun ction, thereby closing theinformation loop to maintain hom eostasis in order to face the harmfulenvironment.

Key words: pineal gland, melatonin, imm une system, circadianrhythm, melatonin receptors, anti-aging


2/17

INTRODUCTION

The pineal gland is known as a regulator of sea-sonal changes in physiological functions of severalspecies, particularly in seasonal breeders (Pkvet1987, Reiter 1989). It is a neuroendocrine gland re-sponsible for the transformation of external signals,mainly photoperiodic information, into a hormonaloutput, interpreted thereafter by internal targetstructures. Photoperiodic information is utilized bythe pineal gland in that it synthesizes and releasesits principal hormone, melatonin, in a rhythmicalfahsion, characterized by a low level during the dayand an increase during the night. This circadianrhythm of melatonin production is observed in allvertebrate species examined to date, regardless oftheir diurnal or nocturnal pattern of locomotor ac-tivity, indicating that melatonin's role in an organ-ism is to provide information on darkness and notabout nocturnal rest. Another essential feature ofthe diurnal rhythm of melatonin synthesis is itsdependence on the length of the night period,thus the pineal gland may act as both "a clock anda calendar" (Reiter 1993b). Interpretation of themelatonin message within the body is essential toadapt the physiological functions of an animal toenvironmental conditions and needs, and thisadaptation would increase the probability of itssurvival. Immune system activity is one of thephysiological capabilities most responsible forthe survival of an individual, whereas the survi-val of the species is guaranteed by reproductorysystem function.

CIRCADIAN RHYTHM OFIMMUNE SYSTEM FUNCTIONThe immune system has lcng been considered as

functioning autonomously, but now good ex-perimental evidence exists for bidirectional interac-tions with the nervous and endocrine systems (forreviews see Goetzl and Sreedharan 1992, Fabris1993, Homo-Delarche and Dardenne 1993). The

role of the immune system consisting of the defenceagainst harmful microorganisms,foreign moleculesor malignant transformed cells has to be coordi-nated over a 24 h period in order to achieve optimalefficiency. Therefore, it is not surprising that, aswith other body functions, immune system activityundergoes circadian changes, and the reciprocalsynchrony is of importance with regard to the main-tenance of homeostasis. On the other hand, diseasemay alter such a rhythm and modify its temporal co-ordination (Lkvi et al. 1992). Adrenal corticoste-roids were the first hormonal factors considered tobe regulators of the diurnal rhythm of the immunesystem.There is substantial evidence that particular sub-types of immune cells, as well as other immune par-ameters, fluctuate differentially over a 24 h periodand exhibit different phase relationships with circu-lating corticosteroid levels (e.g. Eskola et al. 1976,Fernandes et al. 1976, Abo et al. 1981, Skwarlo--Soiita et al. 1983,1987, Indiveri et al. 1985, Angeliet al. 1990, McNulty et al. 1990, Levi et al. 1992).This implies the existence of some other factor(s)responsible for the regulation of the circadianrhythm of immune system function and the pinealgland, in particular its principal hormone mela-tonin, may be a prime candidate. There are sev-eral reasons, but the most important are thefollowing: (1) pineal gland function shows a circa-dian and seasonal periodicity in most species anddeclines with age; (2) circadian rhythm of mela-tonin synthesis strongly depends on lighting condi-tions; (3) melatonin participates in the control ofseveral biological rhythms, including those associ-ated with aging and affective and psychosomaticdiseases, which, in turn, are related to an increasedincidence of infections, autoimmune disorders andcancer (for review see Pierpaoli and Maestroni1987). However, to date, there is scanty experimen-tal evidence demonstrating the role of melatonin asa synchronizer of circadian rh ythcity of variousimmune parameters in humans (Angeli et al. 1990),rats (McNulty et al. 1990, Ding et al. 1995), and chic-kens @Xosolowska-Huszcz t al. 1991, Skwarlo-Soiitaet al. 1991, 1992).


3/17

Pineal-immune interrelationships 343EFFECT OF EARLY

PINEALECTOMY ON T HEDEVELOPMENT OF IMM UNESYSTEMThe first experimental approach to dem onstratereciprocal interdependence between the pineal

gland and immu ne system co nsisted of the ablationof the former in order to exam ine the developme ntand function of the latter. Reports have suggestedthat surgical pinealectomy may exert a stimulatory,inhibitory or no effect on immune function in themammalian species examined to date. These con-troversial results seem to be related to the stage ofthe animals development when pinealectomy wasperfomed, especially in the context of extrapinealmelatonin production (retina, Harderian gland, etc.)( Nowak e t al. 1989 ). Nevertheless, d uring in uterophase of altricial mamm al develop ment, the pinealgland appears some time (in hum an - 3 weeks) priorto the appearance of the thym us rudimen t, and dis-plays transitory neuronal connections with highercentres. The signals coming fro m hypothalam us viane wu s pinealis which disappea rs before birth maybe conveyed to the thymus to accom plish its normaldevelopment (Carderelli 1990).

Surgical pinealectomy during early embryonicdevelopment of mamm als is methodologicaly diffi-cult, if not im possible, whilst the avian emb ryo of-fers an excellent model for the study of this kind.There are several reasons for this, and the most im -portant are that: (1) the avian embryo developswithout direct influence from the mother organism;(2 ) its nervous, endocrine and imm une systems de-velop almost simultaneou sly, and (3) their immun esystem contains two separated primary lymphoidglands: thymus, com parable with that in mam mals,controlling cell-mediated immune response, and,existing only in birds, bursa of Fabricius, a lym-phoid gland furnishing cells which participate inhumoral immune response.Using chicken embryos pinealectomized at 9 6 hof incubation, therefore developing w ithout any in-fluence of the pineal gland, JankoviC et al. (1994a)

clearly demonstrated functional interrelationshipsbetween the pineal gland and development of theimmune system. This early embryonic pinealec-tomy caused a retarded development of both thethym us and bursa of Fabricius, decreased cellularityof both primary lym phoid glan ds, a decrease in thehumoral immune response (number of bursa1 andsplenic hemoly sin producing cells) as w ell as a dim-inishing of several activities of cell-mediated im-munity. M oreover, they also observed a significantchange in the concentration of serotonin, dopamineand noradrenaline in spleen, brain and hypothala-mus; in particular pinealectomy caused a decreasein the content of all biogenic amines examined inthe hypothalam us and an increase in serotonin con-tent in brain and sp leen. It seem s also to prove aninvolvem ent of the chicken pineal gland in the de-velopment of the neuroendoc rine network, which inturn may influence imm une system development.

However, it has to be stressed that in this ex-perimental appro ach the effect of early embryonicpinealectomy was measured in 17-day-embryos,and it may be com pensated later by melatonin corn-ing from ex trapineal sou rces, and therefore, differ-ent effects may be observed in the later stages ofpostnatal development.

IMMUNOMODULATORYACTION OF MELATONINMEDIATED BY OPIOID PEPTIDES

Sinc e the early seventies, evidence accumulatedfor the influence of the pineal gland on the im mnuesystem in laboratory rodents but the results werecontroversial (for review see Meastroni 1993).However, most papers suggested the necessity ofthe intact pineal g land for the normal function of thethymu s, and, in addition, the reported oncostatic ef-fect .of melatonin also im plied an immunoregula-tory activity (reviewed by Blask 1984).

Functional pinealectomy, achieved by exposureof mice for some g enerations to constan t illurnina-tion to cause a su ppression of melatonin synthesis,produced all the symptoms of runting syndrome


4/17

with severe impairment of body growth and anti-body production, and an atrophy of lymphoid tis-sues (Maestroni and Pierpaoli 1981). Similarly, apharmacological inhibition of pineal g land functionin mammals m ay be made by either evening appli-cation of the P-adrenergic antagonist propranolol(which reduces the night peak of melatonin syn-thesis mediated by noradrenaline released frompost-ganglionic sympathetic neurones in darkness)or by daily injections of p-chlorophenyl-alanine, aninhibitor of the synthesis of seroton in, which is anessential melatonin precursor (Maestroni et al.1986). Both treatments significantly reduced anti-body production (measured by the hemolyticplaque-forming ce ll number, PFC , in the spleen ofmice immunized with sheep red blood cells, SRBC ,a commonly used non-pathogenic, thymo-depend-ent antigen), and evening administration of mela-tonin restored the normal immune response. Animmuno-enhancing effect of melatonin w as strictlydependent on the time of administration (Maestroniet al. 1987): the daily even ing injections increasedPFC number whereas the same morning treatmentwas without effect. Stimulation of antibody produc-tion by melatonin was also dose-dependent: be-tween 10 and 1o4p g k g b.w. it induced a significantincrease in PFC num ber, whereas a high pha rmaco-logical dose of 200 mgkg b.w. significantly re-duced the response to SRBC. The effect ofmelatonin was not observed in non-immunizedmice nor in vitro, indicating that it influences theantigen-activated immunocompetent cells via somemediator(s). Exogenous melatonin completelycounteracted the immunosuppressive effect of cor-ticosterone given in drinking water or acuteanxiety-restraint stress on thymus weight and PFCnumber as well as it prevented paralysis and deathof mice infected with sublethal doses of encephalo -myocarditis virus after actue stress. All these im mu-nostimulatory and anti-stre&,,effects of melatoninwere abolished by concomittant administration ofnaltrexone, a specific antagonist of the opiod p-re-ceptors. The antagonizing influence of naltrexonewas also dose-dependent, indicating that the pres-umed m ediator of melatonin action on imm une cells

may be a member(s) of the family of endogenousopioids (EOS), produced under melatonin influenceby antigen-activated immunocompetent cells(Maestroni et al. 1987, 1988, 1989). This sugges-tion was based on results which indicated that notonly EOS ex ert numerous and controve rsial effectson the immun e system and lymphocytes have sur-face receptors for endorph ins and enkephalins (forreview see Wybran 1985), but also immu ne cells areable to synthesize and secrete the opioid-like fac-t o r ( ~ ) Smith and Blalock 1981). Participation ofmelatonin-induced immune opioids (MIIO) in animmu nomod ulatory action in mice was proved ex-perim entally. First, it was found that exogenous 0-endorphin and dynorphin 1-13 mimicked theimmuno-enhancing and anti-stress effect of mela-tonin in its circadian-dependent and naltrexone-sensitive influence (Maestroni and Conti 1989).Subsequently, splenocytes taken from antigen-acti-vated mice, incubated with melatonin were shownto syn thesize and release the agen t(s) restoring thethymus weight of prednisolone-treated, unprimedmice (M aestroni et al. 1989), and acting as an im-munoenhancing and anti-stress factor on thymuscellularity and antibody production in SRBC-im-munized m ice (Maestroni and Co nti 1990). Again,the effect exerted by these active supernatantswas circadian-dependent and naltrexone-sensitive(Maestroni et al. 1989). Similar but less consistentresults were obtained when mitogen-activatedhuman immunocompetent cells were incubatedwith melaton in, as only four out of ten blood donorsprovided cells responsive to melatonin (Maestroniand Conti 1990).

Selective depletion of T cell subpopulationsfrom activated spleen cell suspensions by mon o-clonal antibodies have dem onstrated that the targetcells for melatonin-stimulated release of opioidagonist(s) w e r e ~ 3 ~ 4 'cD ~'), and the active factorcould be the compo und(s) comb ining the propertiesof P-endorphin and dynorphin 1 13 (Ma estroni andConti 1990). Sub sequen tly, the spec ific binding ofa T-helper-derived agon ist to thymic opioid recep-tors and its cross-reactivity with anti-P-endorphinand anti-met-enkephalin antisera finally demon-


5/17

Pineal-immune interrelationships 345strated an opioid character of the factor whichcounteracted the depr ession induced by stress-as-sociated corticosteroids. As the presence of en-dogenous melatonin and antigen activation werenecessary to express this activity, Maestroni andConti (199 1) proposed the ex istence of am elatonin--immuno-opioids network with a physiologicalfunction consisting of providing a correct immunerecovery after the depr ession caused by elevatedcorticosteroids associated with stressful situ-ations.Recently, Maestroni (1993) suggested the use ofmelatonin as an immunotherapeutic agent for im-munodeficiency, i.e. in conditions where m elatoninwas shown to be most active, and indicated ac-quired-immunodeficiency-syndrome (AIDS) as amost dram atic example of this situation. Rationalefor supposed beneficial potential of melatonin inasymptomatic HIV -positive patients is that it is thesame target, i .e. lymphocytes C D ~ + ,or both HIVand melatonin, which could be helpful before thedevelopm ent of AIDS, when the T-helper lympho-cytes still function norm ally.

OTHER MECH ANISMSINVOLVED IN TH EIMMUNOMODULATORYACTIVITY OF MELA TONIN INMAMMALSDuring the last twenty years the num ber of pub-

lished papers describing bidirectional interrelation-ships between the pineal gland, m elatonin and theimmune system have increased several fold (Contiand Maestroni 1994), most of them have beenaimed to elucidate the mechanism(s) involved.General remarks arising from those num erous ex-periments is that the effects exerted by m elatonin onparticular aspects of imm une system function varydepending on species, age and sex of anim als usedas well as on experimental protocol, including sea-son, melatonin dose and route of administration.W e will try to enumerate som e of them, but it im-plies that melatonin exerts its m ultidirectional in-

fluence using several different mechanism s, at leastwithin the imm une system .An anti-glucocorticoid effect of daily melatonininjections on several metabolic param eters, includ-ing prevention of thymus atrophy was found inyoung female rats unprimed with any antigen(Aoyam a et al. 1986). This result was ob tained witha pharmacological m elatonin dose and indicated theposs ibility of an anti-glucocor ticoid activity even innon-immunized animals which is in contrast withthe results of Maestroni et al. (1986, 1987, 1988),but both experimental protocols differ, in particularin species, melatonin dose and route of application.

In 1989 del Gobbo and co-workers demonstratedthat pinealectomy significantly reduced inter-leukin-2 (IL-2) production and natural killer (NK )cytotoxic cell activity, whereas acu te treatment w itha pharmacological dose of melatonin was able toreverse the effect of pinealectomy on bo th parame-ters (Del Gobbo et al. 1989). On the other hand,there are other results which indicate a melatonin--induced suppression of human NK activity in vitro(Lewinski et al. 1989).IL-2 is a lym pho kine released by activated T--helper lymphocytes and plays a fundamental rolein antitumor defense which is effected primarily byNK cells. Therefore, m elatonin acting as an immu-nostimulatory factor and controlling IL-2 produc-tion, together with its well established oncostaticrole, seems to be an excellent candidate for use inclinical oncology. There are several papers indicat-ing that a concomitant adm inistration of melatonin

with IL-2 during immunotherapy of cancer could bein som e tumor histotypes a well-tolerated, effectivetreatment possibly allowing a diminished IL-2 doseand therefore reducing its side effects (e.g. Lissoniet al. 1993a, b, 1994). As the research on the oncos-tatic activity of melatonin , including its clinical ap-plications and therapeutic approaches, becomemore and more frequent, it will not be discussed inthis review.Melatonin seem s to also modulate the secretionof another cytokine playing a key role in the activityof the immune system, y-interferon (INF-y). Hereagain, the effect of m elatonin diametrically differs


6/17

346 K. Skwarlo-Soritain studies in rodents with those in humans. Mela-tonin stimulated INF-y secretion from m ouse spleno-cytes and this effect was several times higher in cellsisolated at night than in the morn ing (C olombo e t al.1992). In cultured hum an peripheral blood lym pho-cytes (PBL) melatonin did not induce production ofINF-y and TNF , but it inhibited the production ofboth cytokines when the cell culture was stimulatedwith PHA . This effect was not opioid-mediated butseemed to be dependent on the seasonal time ofblood collection (DiStefano and Paulesu 1994). Inanother experimental approach, low melatonin con-centrations stimulated INF-y release by hum an PBLactivated with T-cell mitogen, whereas in higherconcentrations it was inhibitory (Muscettola et al.1994). In humans a feed-back circuit between thepineal gland and y-interferon was described: mela-tonin inhibited y-interferon production, which, inturn, stimulated peripheral blood mononuclear leu-kocytes to synthesize melatonin (A rzt et al. 1988,and Finocchiaro et al. 1988, 1991).

Melatonin also exerts a very strong anti-viral ac-tivity in m ice, both in normal a nimals, dexametha-sone injected, or stressed, and this effect was or wasnot counteracted by naltrexone, depending uponage of animals used (Ben-Nathan et al. 199 4).

Another mechanism of melatonin action, anta-gonizing the corticosteroid-induced involution ofthe thymus in mice was proposed by Pierpaoli andco-workers (Pierpaoli and Y i 1990, Lesnikov et al.1992). These authors obtained some indicationsthat melatonin may exert its circadian immuno--modulatory, thymotropic and anti-stress activityby the regulation of the synthesis and/or secretionof hypothalamic or peripheral thyrotropin-releasinghormone (TRH) and this effect was not thyroid-de-pendent. An electrolytic lesion of the anterior hypo-thalamic area resulted in an involution of thethymus and a reduction in peripheral blood lympho-cyte number, reversed sign,iicantly by daily eve-ning treatment w ith TRH or melatonin. Again, theserestoring effects were not dependent on the stimu-lation of the thyroid gland, but were an tagonized bynaltrexone. On the basis of the above results, Pier-paoli's research group indicated TRH as a suitable

candiadte for a transducer of pineal-recorded exter-nal stim uli, leading to the adaptation of an organismto environm ental variables, including regulation ofimmunity as a reaction to the antigens, stress andother noxious a gents.On the other hand, TRH is a potent prolactin(PRL) releasing factor (review ed by M artinez de laEscalera and W einer 1992), and recently the partici-pation of PR L in the anti-stress effect of melatoninon the immune system of rats was hypothesized(Liebman et al. 1993). Exogenous melatonin de-creased basal PRL release and potentiated th e PRL--increasing effect of stress and this action wasEOS-m ediated. P RL is a well know n stress-inducedfactor (for reviews see Van de K ar et al. 1 991 andKelley et al. 1992) and its immunostimulatory ac-tivity, antagonizing the effect of glucocorticoids(Bernton et al. 1992 ) in both ma mm als and birds iswell established (for review se e Berczi 199 2, andSkwarlo-Sorita 1 992), with s imilar imm une systemtarget, as for melatonin (T -cell imm unity).

Finally, it was found that pinealectom y imp airsand melatonin enhances the antibody-dependentcellular cytotoxicity in mice, and this effect wassex- and seasonally-dep endent, suggesting that sexhormones may be involved in the pineal effect onsome parameters of immune system function (Giordanoand Palermo 199 1, Vermeulen et al. 1993, Palermoet al. 1994). As melatonin is a principal environ-mental signal transducer co ntrolling gonadal devel-opme nt and function , at least in seasonally breedingspecies (Morgan 1990), and on the other hand, sexsteroids are implicated in the well docu men ted sex-ual dimorphism in the immune response (Grossmanet al. 1991), the above mentioned mechanism ofmelatonin action upon the imm une system seem s tobe important.

Taking the experimental results cited abovetogether, it is admissible the ex istence of am uli-ste ptransmission of information coming from externalenvironment via pineal gland-melatonin-TRH-PR Landlor GnRH-gonadotrophins-sex steroids to theimmune system. This mechanism(s) may operateparallelly to the melatonin-induced irnmuno-opioids(MIIO, proposed by Maestroni and co-workers,


7/17

Pineal-immune interrelationships 3471994), and/or direct action, using specific mela-tonin receptors on immune cells (see below). Thislast possibility was recently suppo rted by the dem -onstration that melatonin in vitro significantly in-hibited the incorporation of [ 3~ ]th yr ni di nento bothnormal mouse and human lym phocytes and T-lym-phoblastoid cell lines whereas it stimulated the myelo-ma cell proliferation (Persengiev and Kyurkchiev1993). This first report dealing with a direct mela-tonin influence on lymphoid cell proliferationopens, we believe, a new direction of research onthe mechanism(s) of melatonin action within theimmu ne system.

ELECTROMAGNETICENVIRONMEN T AND PINEALGLAND FUNCTIONAs was already discussed, light inhibits mela-

tonin synthesis within the pineal gland. However,visible light constitutes o nly a v ery narrow portionof the total electromagn etic spectrum , which variesfrom a very short, thus high energy ionizing radia-tion (X-rays, UV), to an extremely low frequency(ELF), long waves, with energy so low that it is in-capab le of extracting electron s from atom s (non-io-nizing electromagnetic waves). EL F waves derivefrom electrical power lines and electrical appliancesand produce charges o r currents on the surface ofbodies or objects exposed. Widespread use of elec-tric power markedly changes the electromagneticenvironment, especially in countries with well-de-veloped industry. On the other hand, m agnetic fieldreadily pass through all materials including thebody, and can induce eddy currents in it. There areseveral studies suggesting thai the exp osure of hu-mans to high or unusual electric and magn etic fieldsinduces a higher than normal incidence of cancer(Reiter and Richardson 1992, Reiter 1993, 1994).

Experiments on laboratory rodents have dem on-strated that unusual electric, magnetic or electro-magnetic fields induce a reduction of melatoninsynthesis and secretion, via an inhibition of N-ace-tyltransferase activity, a key enzy me resp onsible for

the circadian rhythm of melatonin. Since bothvisible light and E LF electromagne tic fields evokethe sam e effect in the melatonin synthesis pathway,a similar mechan ism of action may be suggested. Adiminished melatonin message or perturbed circadianrhythm m ay, in turn, have a significant physiologicalconsequences, including diminished antioxidantactivity and anti-cancer protection (see below ), (Reiter1994).On the other hand, it has been demonstrated thatthe expo sure of the rat brain occipital region to staticmagnetic fields results in a significant immuno-potentiation (Janko vi et al. 1994 ). In aging rats, im-plantation of micromagnets to the brain occipitalregion not only enh anced both the cellular and hu-moral imm une response to a T-dependent antigen,but also abrogated imm unodeficiency induced bypinealectomy. This indicates the role of the pinealgland, and presumably melatonin, in magneticfield-induced imm unopotentiation, and on the otherhand, demonstrates a functional relationship be-tween the central nervous system , pineal gland, im-mune system and static magnetic fields. Thepresence of melatonin bindin g sites within the cen-.tral nervous sy stem implies the involvem ent of thebrain in the imrnunomodulatory activity of the pi-neal gland.

ANTI-AGING MELATONINACTIVITYOn e of the most impressive effects evoked by the

pineal g land is its anti-aging activity demo nstratedin laboratory rod ents in which grafting of the entirepineal from young donors (Pierpaoli et al. 1991,Lesnikov and Pierpaoli 1994) or melatonin treat-ment (Maestroni et al. 1989, Caroleo et al. 1994, )caused a significant rejuvenation in old animals.Aging or senesen ce is a multifactorial postmatura-tional process that results in the heterogen ous pat-terns of a progressive morbidity and disability(Seeman and Rob ins 1994), manifested also by ameasurable decline in immune function (Ershler1993). There are several theories of aging, amongthem the free radical theory hypothesizes that the


8/17

aging and associated d egenerative processes resultfrom the accumulation of free radicals, continuous-ly produced as a normal product of aerobic cellularmetabolism (Meydani 1992). It is also well do-cumented that active oxyg en species are producedupon exposure of organisms to ionizing radiation,ultraviolet light, and some chemical carcinogens.Free radicals are atoms or molecules having an un-paired electron, i.e. 0 - 2 , HO*, H202, and usuallythey are short-lived becau se of their highly reactivenature. They can damage molecules important tocellular function, including D NA , and this type ofdamage can be both mutagenic and carcinogenic.~ h d r e re multiple enzymatic and non-enzymaticantioxidant defense systems in cells to protectagainst the damag ing effects of free radicals. Thesedefense systems consist of the removal of free radi-cals or in slowing their production , and in addition,there are also molecules which scaveng e or quenchfree radicals once they are produced. T hese mole-cules are more useful in preventing or delayingaging and age-related diseases. Among the bestknown free radical scavengers are tocophero l (vit.E), ascorbate (vit. C), glutathione, and recently, anantioxidative role of melatonin was proposed. Itwas demonstrated that melatonin w as several timesmore potent as a hydroxyl radical scavenger thanglutathione and m annitol. Moreover, in rats treatedwith safrole, a highly toxic carcinogen which causeshepatic DNA damage via production of toxic freeradicals, melatonin administered in relatively lowdoses (750- to 1,500 -times lower than that of sa-frole) was extremely efficient in DNA protection(Reiter et al. 1994).

Free radicals are molecules participating,together with cytokines, in a developing immuneresponse, especially in the destruction of toxic bac-teria or pathologically changed cells. Recently itwas demonstrated that activated macrophages syn-thesize another type of free radical, nitric oxide,which, as well as ending bacterial destruction , acti-vates the generation of a new very active hydroxylradical. Immune cell-derived free radicals are ex-tremely useful to effect an immunosurveillanceagainst abnorm al cells, but, unfortunately, they can

also act against their own lymphocytes leading tosome tissue dammage. The safe level of irnrnune-derived free radicals strongly depends on thepresence of antioxidant agents, including the intra-cellular level of zinc (Favier 1 993).Recently, it was demonstrated that melatonincan modulate zinc turnover (Mocchegiani et al.1994a, b). With adv ancing age not only plasma m e-latonin declines progressively, but this decrease isalso accompanied by thym ic degeneration , reducedplasma level of the zinc-bound biologically activeform of thymic horm one, thymulin (Dardenne et al.1982), and by low zinc plasma lev els. In old mice,both m elatonin treatment or pineal grafting into thethymus, corrected all immune p arameters, includ-ing thym us cellularity, peripheral lymphocyte nu m-ber and responsiveness as well as restored the zincpool to similar to that observed in young mice(Mocchegiani et al. 1994b).It is important to notice that the activity of me-latonin as a very potent endogenous antioxidantmay be exerted everywhere within the body, be-cause, as a highly lipophilic compo und, it can easilypass through all morpho-physiological barriers, andprotect every portion of the cell from radical-in-duced dam age. Moreover, there is substantial evi-dence that melatonin is produced in m any o rgans,in addition to the pineal gland , including peripheralblood leukocytes (Finochiaro et al. 1991), andtherefore may represent a very important compo-nent in the modulation of immune function. Thispoint of view seems to be strongly supported by thewell known fact that advancing age, in both humansand laboratory animals, is associated with a pro-gressive reduction in the concentration and circa-dian rhythm of melatonin (Reiter 1992). On theother hand - aging is characterized by a deficiencyin the cellular imm une respo nse as a result of rela-tively inert memory T cells and reduced T cell ac-tivity, influencing also humoral immnuity. Thesenescence of the immu ne system has been provento be causative in the development of age-associ-ated autoimmune phenomena, infectious diseasesand neo plasia (Ershler 1993). It is admissible, thatage-related accum ulation of free radicals, in parallel


9/17

Pineal-immune interrelationships 349with a decline in endogenous melatonin rhythm,may be, at least partly, respons ible for a senescenceof imm une sys tem efficiency.

INFLUENCE OF IMM UNESYSTEM ON PINEAL GLANDFUNCTIONIf the pineal gland really participates in the trans-mission of information between the external envi-

ronment and internal milieu, and plays a role in themodu lation of imm une system function, it is essen-tial that the immune system in turn sends its own in-formation to the pineal gland , and these signals haveto be adequately transformed to maintain homeos-tasis. Experiments which indicate that the pinealgland is able to receive this kind of information havejust started to appear, and it seems that cytok ines, asoluble factors produced by imm une cells, are thebest candidates to effect this very important func-tion. irst, it has been dem onstrated that INF-y en-hanced melatonin production by the rat pineal g landin organ cultures (Withyachumnarnkul et al.1990a), whilst, on the other hand, it suppressedNAT activity stimulated with isoproterenol, a P-adrenergic receptor agonist (Withyachumnarnkulet al. 1991). Two possible mechanisms of INF-y ac-tion upon the pineal gland in rats have been pro-posed: a faciliation of tryptophan entry into thesympathetic nerve terminal and pinealocyte, anddown-regulation of the P-adrenergic receptors onthe pinealocyte mem brane. Th e end result, eitheran increase or a decrease of melatonin produc-tion, depends on the d oses of INF-y and the levelof noradrenergic stimulation of the pinealocyte(Withyachum narnkul et al. 1930b).

Th e existence of bilateral interplay between th epineal gland and immu ne system has recently beensupported by ano ther experimen t in rats, indicatinga significant dose-depen dent decrease in serum me-latonin level under the influen ce of exogeno us rec-ombinant human interleukin 1P (IL- 1P), abolishedby anti-human IL- 1 receptor an tibody (Mucha et al.1994). IL-1 is a cytokine w ith pleiotropic activity

within the neuroendocrine and immune systems,and the abo ve results seem to indicate an importantrole in transmitting information between the im-mune sy s em and pinealocytes, by direct action viaspecific receptors. Recently, the same researchgroup have demonstrated that colony-stimulatingfactors (G-CSF and GM-CSF), glycoproteins se-creted by activated immune cells, mainly macro-phages, stimulated both in vivo and in vitro ratpineal melatonin synthesis, in a dose-dependentway ( ~ ~ l i l i s k at al. 199 5).

EFFECT OF MELATONIN ONIMMUN ITY IN BIRDSAll the previously mentioned experimental re-

sults and hypotheses described an immuno-regula-tory function of the pineal gland and melatonin inmammals and this field of research is well under-stood because of possible application of exogenousmelatonin in hum an im muno therap y .Nevertheless,the pineal gland was demonstrated to play an essen-tial role in the transduction of external informationinto the organ isms of all vertebrates, with numerousdifferences between mammals and lower verte-brates in terms of several pineal gland functions, es-pecially with respect to the direct photosensitivityand the mechanism of melatonin synthesis regula-tion.To our knowledg e, there is no published infor-mation concerning im muno regulation by the pinealgland in ectotherms, whereas that in birds is veryscanty, but, as it was already mentioned, avianspecies offers a very useful experimental model toexamine pineal - immun e interrelationships.

It was demonstrated in several experiments thatin the chicken, the circadian rhythm of different im-mune parameters was strongly d ependent upon thepresence of an intact pineal gland, e.g. pinealec-tomy at the first week of age influenced the diurnalrhythm of both granulocyte number and serum ly-sozyme con centration in 5-week-old chickens, andboth rhythms were restored by daily melatonin butnot vehicle injections (Roso~owska-Huszczet al.1991). Also, in chicke ns w ith an intact pineal gland,


10/17

350 K. Skwarlo-Soritaexogenous melatonin modified the circadianrhythm of immune system function (measured bythe number of white blood cells, WBC, and theirfractions, as well as by the level of circulating ag-glutinins anti-SRBC and PFC number), and theeffect was more dependent on the time of horm oneadminis t ra t ion than on the d ose used (Skwarlo--Sofita et al. 1991, 1992). However, we were notable to demonstrate any immunostim ulatory effectof melatonin in the chicken, even in experimentalconditions in which it stimulated PFC number inmice (Skw arlo-Sorita et al. 1 992).Recently, the effect of pinealectomy on nonspe-cific immune parameters as well as serum hor-mones level were examined in adult male andfemale ring doves (Rodriguez and Lea 1994). Im-mune parameters were examined 6 month aftersurgery (pinealectomy or sham operation) once aday, thus no information was obtained about the ef-fect of pinealectomy on the circadian rhy thm of im-mune parameters, but here again, there is no clearcut indication about an immunostimulatory effectof the pineal gland. On the con trary, some parame-ters were increased in pinealectomized birds, som enot influenced, and an increased production of freeradicals in heterophils, indicating a reduced m ela-tonin concentration in pinealectomized birds. Im-munization with a soluble antigen, normal sheepserum , similarly influenced phagocytic parametersin both pinealectomized and sham operated birds.

Th e above mentioned results are in apparent con-tradiction with those obtained recently by JankoviCet al. (1994a) who demonstrated a diminished im -mune response in pinealectomised chicken em-bryos. The necessity of the pineal gland indeveloping chicken em bryos to effect a normal im-mune response, found by JankoviC research group(1994a) does not exclude the possibility of com pen-sation of melatonin synthesis in extrapineal sites inthe later stages of postnatal life.In the chicken with an intact pineal gland m ela-tonin in a dose effective in mice did not antagonizethe immunosuppressive effect of corticosteronegiven in drinking water, and its effect was not nal-trexone-dependent. However, a very high mela-

tonin dose (2,000 pgkg BW), and naloxonecounteracted the effect of corticosterone on someparam eters, suggesting a different sensitivity to me-latonin and opioid antagonists in mammals andbirds (Skw arlo-Sonta et al. 1994a).

Recently it was demonstrated that in the chickenbetween 2 and 8 weeks of age the pineal gland is in-filtrated by lymphocytes which form an accumula-tion well organized, like in peripheral lymphoidorgans (Olah 1995). Intra-pineal lymphoid cellswere characterized using the monoclonal anti-bodies, and they ap peared to be T cells as well asIg-producing plasma cells, forming a real lym-phopineal tissue. T he phy siological significance ofthe transitory lymphoid infiltration of the pinealgland is unknown, but it may be a very special mani-festation of the neuroendocrine-immune interac-tions.

Th e results obtained to date seem to indicate thatthe difference between m amm als and birds in termsof pineal gland function may be extended to its im-munomodulatory potential, but needs further ex-perim entation. It is especially necessary to elucidatethe effect of sex, age and season upon the influenceof melatonin on particular immune parameters inbirds, as these factors were demonstrated to mod ifythe immunomodulatory activity of melatonin inmice (Giordano and Palermo 199 1, Vermeulen etal. 19 93, Palermo et al. 19 94, Maestroni et al. 1 994).

MELATONIN RECEPTORSWITHIN THE IMM UNE SYSTEMFor several years the central nervous system wasconsidered as a site by which melatonin may m odu-late the rhythmicites, observed in mammals. The

coincidence of the peaks of melatonin concentra-tion and its receptors in the brain in terms of diurna lrhythms m ay determine the responsiveness to me-latonin of the neuroendocrine system (Anis et al.1989, Stankov and Reiter 1990, Stankov et al.1991a, b). Using 2-[125~]io dom elatonin,n agonistwith a high specific activity, binding of melatoninin peripheral organs [e.g. gastrointestinal tract (Lee


11/17

Pineal-immune interrelationships 351and Pang 1991), reproductive organs (Ayre et al.1992, Wang et al. 1992),kidney (Song et al. 1992)],including the immune system, have been demon-strated, implying a direct action of melatonin on tar-get tissues outside the central nervous system.

In 1989 Niels in the hamster, and thereafter Yuand co-workers (1991) in other mammals and birdsdemonstrated the presence of iodomelatonin bind-ing sites in spleen, with higher density in birds(duck, chicken) than in mouse, whilst no bindingsites were detected in the spleen ofthe rat. Bindingof 2-[125~]iodomelatonino the spleen membranepreparations was specific, reversible, and time-de-pendent, and binding parameters (Kd and Bmax)suggested that these binding sites belonged to the M1class of melatonin receptors proposed by Dubocovichin 1988 (Pang et al. 1991a). Subsequently, high af-finity specific binding of melatonin was describedin membrane preparations form spleens of guineapig (Poon and Pang 1992,1994), chicken (Pang andPang 1992) and pigeon (1993), duck thymus (Liu etal. 1992, cited after Liu and Pang 1992) and bursaof Fabricius (Liu and Pang 1992), rat thymus (Martin--Cacao et al. 1993) and in human blood leukocytes(Lopez-Gonzalez et al. 1992, Gu e~ e rot al. 1994).Our own data (Skwarlo-Sonta et al. 1994b) hasdemonstrated in 4 week-old cockerels the presenceof very abundant 2-[125~]iodomelatonin indingwithin the brain and a much lower binding sites den-sity in lymphoid tissues, as well as in the gonads. Ofthe lymphoid tissues examined, the highest io-domelatonin binding was found in membrane.preparations isolated form the bursa of Fabricius(comparable with those of Liu and Pang 1992),much lower in the spleen, and only traces in the thy-mus.

In human peripheral blood leukocytes Scatchardanalysis revealed two classes (high- and low-af-finity) of melatonin binding sites on lymphocytes,whilst granulocytes possessed only one classe, alow-affinity binding site (for review see Guerrero etal. 1994). The high-affinity melatonin binding siteon peripheral lymphocytes may be responsible forrecognition of the circulating hormone by the lym-phocytes, the low-affinity binding sites are unlikely

to be related to a physiological role of melatoninwithin immune system. Moreover, the authors sug-gest that these lymphocyte low-affinity bindingsites may be due to the presence of granulocytes inthe blood lymphocyte preparations.

Similarly, in partially purified membrane prep-arations from the rat thymus, two classses of mela-tonin binding sites have been identified: high- andlow-affinity sites, which, additionally, exhibit a de-crease in binding capacity during the two firstweeks of age: melatonin binding was highest innewborn rats but in the second week of age it wasas low as in adult rats (Martin-Cacao et al. 1993).Our recent studies on early postnatal developmentof melatonin binding sites within the chicken im-mune system have also revealed a decrease in hor-mone binding during the first weeak of age(Dziwinski et al., unpublished data). In membranesprepared from whole thymi, specific melatoninbinding increased from 0.25 fmoVmg protein at 2ndday after hatching to 0.60 fmoVmg protein at 7thday, and thereafter it decreased to the very low value(approx. 0.10 fmoVmg protein) remaining constantuntil the 4th week of age. The pattern of postnatalchange in melatonin binding sites in the thymus ofrats and chickens are different and their physiologi-cal relevance remains to be establish. However, itmay be considered as one of the reasons for the dif-ferent effects of melatonin on immune parametersobserved in the in vivo experiments.

It is also of interest that when membranes wereobtained from isolated chicken thymocytes and re-mained tissue debris, both thymic subfractions ex-hibited melatonin binding ability, which wasmaximal at the 4th day after hatching, and de-creased thereafter to the value observed in the wholegland after the 1st week of age. This result impliesthe possible involvement of melatonin in the intra-thymic education of developing T cells in chickens,as well as some role of the thymic microenviron-ment in melatonin message transmission betweenblood and immune cells.

Developmental changes in melatonin bindingsites number were also measured in membranepreparations from the bursa of Fabricius and spleen,


12/17

obtained from both w hole glands and their subfrac-tions (Dziwiriski et al., unpublished data). Mela-tonin binding site density varied with gland and age:highest and variable was in the spleen, suggestingthat this secondary lymphoid g land contains a moreheterogenous cellular composition in relation tosensitivity to melatonin. In membranes from w holebursa of Fabricius, melatonin binding was relative-ly stable until the 21st day of life, but, surprisingly ,it increased continuously in isolated bursa1 lym-phoid cells. On the other hand, in the lymphoidglands examined, melatonin binding by tissue de-bris was highest in the bursa of Fabricius. Thephysiological significance of these results and pre-cise localisation of melatonin binding sites withinthe chicken immu ne system deserve further studies,but results presented to date, together with those ob-tained in developing rats seem to indicate a devel-opmental interdependence between the immunesystem and pineal gland. They are in line with pre-viously demonstrated impairment of immunepotential by neonatal pinealectomy (Devecerski1963) as well as with the recent results published byJankoviC et al. (1994) on the effect of em bryon al pi-nealectomy on the developmen t of the chicken im-mune system.

Our data (Skw arlo-Sorita et al. 1 994b ) obtainedin 4 week-old cockerels also demonstrated thatneither Kd nor density of melatonin binding siteswere modified by im munization with SR BC, whichcaused a significant stimulation of serum anti-SR BC agglutinins. This result suggests that in im-munocompetent birds, melatonin binding by bothprimary (thymus and bursa of Fabricius) and sec-ondary (spleen) lymphoid organs is unrelated to im-mune system activation by a T-dependent antigen.It remians in sharp disagreemelit with results ob-tained by Poon et al. (1994) in the duc k treated for7 days with pharmacological doses of cortisol (1 mgper 2-week-old bird daily). I nese authors obtaineda significant reduction of Bm ax in co rtisol injectedbirds, concomitant with a de crease in body and pri-mary lymphoid organ weights (thereby relativeorgan weights w ere not influenced) and no signifi-cant increase in serum melatonin content. Reduc-

tion of melatonin binding site number in cortisol-in-jected, very young birds was attributed by the auth-ors to a change in their immune status, though n otclearly docum ented. Our own results (Skwarlo-Soritaet al. 1994b, and unpublished data) demontstratedin the 5-week-old chicken, treated for 5 days withcorticosterone (a major adrenal corticoid in avianspecies, De Roos 1961) in drinking water, at a doseapprox. of 1,2 m g h ir d daily, a reduction of relativethymus and bursa of Fabricius weight by 40-65 and52-60% , respectively, simultaneous with a 60% de-crease in serum antibody level. A reduction of me-latonin binding density under the influence ofcortisol injections, observed by Poon et al. (1994)is probably rather related to bind ing site down regu-lation by the increased serum melaton in concentra-tion, than with any depressed a ctivity of the imm unesystem. On the other hand, W ang et al. (1993) havereported a significant increase in the number of me-latonin binding sites on spleen membrane preparations,concomitant with unchanged binding by the brain in hy-drocortisone-treated pigeons.

Melatonin binding sites within the immun e sys-tem undergo diurnal changes, with the higher densityduring the day (Liu and Pang 1992) and an increaseunder constant illumination (Poon and Pang 1992).To d ate, information on m elatonin signal trans-duction and the post-receptor mecha nism of its ac-tion within the immune system is very scarce(Lopez-Gonzalez et al. 1992, Poon et al. 1993, Poonand Pang 199 4,199 4a) but seems to indicate that themelatonin binding site is a single type of receptorcoupled to a G-protein. However, it has recentlybeen demonstrated that melatonin binding sites inchicken primary (bursa of Fabricius) and secondary(spleen) lympho id organs may co ntain subtypes ofreceptor which form different receptor-G protein-effector com plexes (Poon and Pang 1994b). Inhuman lymphocytes, melatonin had no influence onthe basal cA M P level however it stimulated cG M Pand increased the effect of V IP on cAM P produc-tion (L opez-G onzalez et al. 1992). It was suggestedthat in human blood lymphocytes, high-affinitybinding sites are coupled with the potentiation ofthe V IP effect on CA M P, and low-affinity binding


13/17

Pineal-immune interrelationships 353sites are coupled with activation of cG M P produc-tion. On the other hand, physiological concentra-tions of ~ a +nd c a 2 + seem to play a m odulatoryrole in melatonin binding to its receptor in the gui-neap ig spleen (Poon and Pang 1994). Very recentlyGuerrero's research group have published resultsindicating that high-affinity melatonin binding sitesin rat sp lenocytes fulfilled all the necessary criteriafor a single class of receptor. M oreover, melatoninwas demonstrated to inhibit CA MP productionstimulated by forskolin, similar way to that ob-served using pituitary cells (Morgan et al. 1989).The affinity of these binding receptors suggest thatthey may recognize physiological melatonin con-centrations in the serum (Rafii-ElIdrissi et al. 1 995).It remains to be established whether or not m e-latonin binding sites within the imm une system m ayparticipate directly in the imm unom odulatory activ-ity of this hormon e, proven to date at least in mam -mals. In fact, when the e ffect of different doses ofexogenous melatonin on its binding sites was exam -ined in guinea pig spleens, a dose-dependent de-crease of binding density was observed (Poon andPang 1994a). It is the first indication that melatonin,by a modulatory influence on its own binding site,may act directly upon the imm une system function.How ever, it is impossible to answ er, whether and inwhat extent described melatonin treatment modi-fied that function, as imm une parameters w ere notmeasu red in this experiment.

CONCLUSIONSThe results reviewed here indicate that the pinealgland, a neuroendocrine organ, is involved in a bidi-rectional interrelationship with the immune system

(Fig. 1). A special position of t ic pineal gland in thisscheme is due to its particular ability to transduceexternal information on light and the electro-mag-netic field, not perceived by both neu ro- and endo-crine systems, into a biochemical messageunderstood by the whole body. This message, con-sisting of daily rhythms of melatonin synthesis andrelease, is thereafter transmitted to the im mun e sys-tem using several intermediate mechanisms, in-

P S Y C H O G E N I C S T l h lU L 1 ,S TR E S S LIGHT, ELECTR 0

NERVOUSSYSTEM

f x tENDOCRINE IMMUNESYSTEM SYSTEM I

4

/ M I L I E U

Fig. 1.Pineal gland invo lvem ent in the signal transduction be-tween environmental information and immu ne, nervous andendocrine systems.cluding the endogeno us opioid system , various hor-mo nes, cytokines as well as the specific melatoninbinding sites within imm nue sy stem itself, which, inturn, is able to produce some factors (cytokines)which con trol pineal gland function. The highly ly-pophilic melatonin molecule may also penetrateevery cell of the body, including immune cells,scavenge produced free radicals and act as a verypotent anti-aging and anti-neoplastic factor. Reci-procal interrelationships between the pineal gland,nervous, endocrine and imm une systems during de-velopm ent are essential for the normal acquiring ofimmune competence. The pineal gland is also animpo rtant component of the neuroendo crine systemrespo nsible for the resetting of circad ian rhythmicityof several physiological processes, therefore it alsoseem s to participate in the control of temporal organ-ization of immune system function.

ACKNOWLEDGEMENT

Dr Robert W. Lea (U niversity of Central Lanca-shire, Preston) is gratefully acknowledged for thelinguistic supervision of the paper.


14/17

354 K. Skwarlo-SontaREFERENCES

Abo T., Kawate T., Hinuma S., ItohK,Abo W ., Sato J., Kum agaiK. (1980) The circadian periodicities of lymphocyte sub-populations and the role of corticostero id in human beingsand mice. In: Recent advances in the chronobiology of al-lergy and imm unology (Ed. M.H.Sm olensky). PergamonPress, Oxford, p. 301-316.

Aoyam a H., M ori W., Mo ri N. (1986) Anti-glucocorticoid ef-fects of melatonin in young rats. Acta Pathol. Jpn. 36:423-428.

Angeli A., Gatti G ., Masera R ., Sartori M.L., Carignola R.(1990) Chronobiological aspects of neuroenodcrine-im-mu ne interactions. Intern. J. Neuroscience 51: 341-343.Anis Y ., Nir I., Zisapel N. (1989) D iurnal variations in me la-

tonin binding sites in the hamster brain: impact of mela-tonin. Mol. Cel. Endocrinol. 67: 121-129.Arzt E.S., Fernandez-CasteloS., Finocchiaro L.M.E., CriscuoloM.E., Diaz A., Finkielman S., Nahmod V.E. (1988) Immu-nomodulation by indoleamines: serotonin and melatoninaction on DNA and interferon- synthesis by human periph-eral blood mononuclear cells. J. Clin. Immunol. 8: 513-520.

Ayre E.A., Yuan H., Pang S.F. (1992) The identification of125~-labelledodomelatonin-binding sites in the testes andovaries of the chicken (Gallus domesticus). J. Endocrinol.133: 5-11.

Ben-Nathan D., Maestroni G.J.M., Lustig S., Conti A. (1994)Protection by melatonin in mice infected with SemlikiForest virus. Adv. Pineal Res. 7: 125-130.Berczi I. (1992) The immunology of prolactin. Sem inars Re-prod. Endocrinol. 10: 196-219.

Bernton E., Bryant H ., Holaday J., Dave J. (1 992) Prolactinand prolactin secretagogues reverse immunosuppressionin mice treated with cysteamine, glucocorticoids, or cy-closporin A. Brain Behav. Imm un. 6: 394-408.Blask D.E. (198 4) The pineal: an oncostatic g land? In: The pi-neal gland (Ed. R.J.Reiter). Raven Press, New York, p.253-284.

Cardarelli N.F. (1990) Th e role of a thymus-pineal axis in animmun e mechanism of aging. J. Theor. Biol. 145: 397-405.Caroleo M.C., Doria G., Nistico G. (1994) Melato nin restoresimmunodeprassion in aged and cyclophosphamide-treated mice. Ann. N.Y. Acad. Sci. 719: 343-352.

Colombo L.L., Chen G.-J., Lopez M.C., Watson R.R . (1992)Melatonin induced increase in gamma-interferon produc-tion by murine splenocytes. Im mu nol. Lett. 33: 123 - 126.Conti A., Maestroni G.J.M . (1994) Melatonin-induced imm u-no-opioids: role in lym phoproliferative and au toimmunediseases. Adv. Pineal Res. 7: 83-100.

Dardenne M ., Pleau J.M., Nabama B., Lefancier P., Choay J.,Bach J.F. (198 2) Contribution of zinc and other metals tothe biological activity of the serum thymic factor. Proc.Natl. Acad. Sci. USA. 7 9: 5370-5373.

DeRo os R. (1961) The corticoids of the avian adrenal gland.Gen. Co mp . Endocrinol. 1: 494-512.DiS tefano A., Paulesu L. (1994) Inhibitory effect of melatoninproduction on INF gamma or TNF alpha in peripheral

blood mon onuclear cells of som e blood donors. J. PinealRes. 17 : 164-169.

Del G obbo V., Libri V., Villani N., Calio R. Nistico G . (1989)Pinealectomy inhibits interleukin-2 production and natu-ral killer activity in mice. Int. J. Immunopharmacol. 11:567-573.

Eskola J., Frey H., Molnar G., Soppi E. (1976) Biologicalrhythm of cell mediated immun ity in man. Clin. Exp. Im-munol. 26: 253-257.Ershler W.B. (1993) The influence of an aging immun e sys-tem on cancer incidence and progression. J. Gerontol.Biol. Sci. 48: B3-B7.

Fabris N. (1994) Neuroendocrine regulation of immunity.Adv. Pineal Res. 7: 41-56.Favier A. (1993) Place des radicaux libres de l'oxygene dansla response immunitaire. In: VIIe journees de medecinefonctionnelle (Ed. John Libbey). Eurotext, Paris, p. 13-22.

Fernandes G ., Halberg F., Yunis E.J., Good R.A . (1976) Cir-cadian rhythmic plaque-forming cell response of spleensfrom mice immun ized with SRB C. J. Immunol. 117: 962-966.Finocchiaro L.M.E., Nahmod V.E., Launay J.M . (1991) Me-latonin biosynthesis and metabolism in peripheral bloodmononuclear leucocytes. Biochem . J. 280: 727-73 1.Giordano M., Palermo M. (1991) Melatonin-induced en-hancement of antibody-dependent cellular cytotoxicity. J.Pineal Res. 10: 117-121.

Goetzl E.J., Sreedharan S.P. (1992) Med iators of commun ica-tion and adaptation in the neuroendocrine and immunesystem. FASEB J. 6: 2646-2652.

Grossman C.J., Roselle G.A., Mendenhall C.L. (1991) Sexsteroid regulation of autoim munity. J. Steroid Biochem .Molec. Biol. 40: 649-659.Guerrero J.M., Calvo J.R., Osuna C., Lopez-Gonzalez M .A.(1994) Binding of melatonin by lym phoid cells in hum ansand rodents. Adv. Pineal Res. 7: 109-117.

Hom o-Delarche F., Dardenne M . (1993) The neuroendocrine-immune axis. Springer Semin. Immunopathol. 14: 221-238.

Indiveri F., Pierri I., Rogna S., Poggi A., Montaldo P., R omanoR., Pende A., Morgano A ., Barabino A., Ferrone S. (1985)Circadian variations of au tologous mixed lym phocyte re-actions and endogenous cortisol. J. Immunol. M ethods 8 2:17-24.

JankoviC B.D ., KneieviC Z., Koji L., Nikoli V. (1994a) Pinealgland and imm une system. Imm une functions in the chickembryo pinealectomized at 86 hours of incubation. Ann.N.Y. Acad. Sci. 719: 398-409.JankoviC B.D., Nikoli P., cupiC V., Hla dni K. (1994b) Po ten-tiation of immune responsiveness in aging by static mag-


15/17

Pineal-immune interrelationships 355netic fields applied to the brain. Ann . N.Y. Acad. S ci. 719:410-418.

Kelley K.W., Arkins S., Li Y.M, (1992) Growth hormone,prolactin, and insulin-like growth factors : new jobs fo r oldplayers. Brain Behav. Imm un. 6: 317-326.Lee P.P.N., Pang S.F. (1991) Identification and charac-terization of melatonin bind ing sites in the gastrointe stinaltract of ducks. Life Sci. 50: 117-125.Lesnikov V.A., Korneva E.A., Dall'ara A., Pierpaoli W.(1992) The involvem ent of pineal gland and melatonin inimmunity and aging: 11. Thy reotrop in-releasin g horm oneand m elatonin forestall involution and prom ote reconstitu-tion of the thymus in anterior hypothalamic area (AHA )-lesioned mice. Intern. J. Neu rosci. 62: 14 1-153.

Lesnikov V.A., Pierpaoli W. (1994) Pineal cross-transplanta-tion (old-to-young and vice versa) as evidence for an en-dogenous "aging clock". Ann. N.Y. Acad. Sci. 719:456-473.

LCvi F., Canon C ., Depres-Brummer P., Adam R., Bourin P.,Pati A ,, Florentin I., M isset J.L., Bismuth H. (1992) Therhythmic organization of the imm une network: implica-tions for the chronoph arma colog ic delivery of interferon s,interleukins and cyclosporin. Adv. Drug Deliv. Rev. 9: 85 -112.

Lewinski A. , ~e la zo w sk i ., Sewerynek E., ~erek- el en G.,Szkudlinski M. (1989) Melatonin-induced immunosup-pression of human lymphocyte natural killer activity invitro. J. Pineal Res. 7: 153-164.Liebmann P.M., Hagmuller K ., Schauenstein K. (1993) Pro-lactin, a possible med iator in antistress effects of m ela-tonin on the im mune system. A study in freely moving rats.Poster presented at 1st. Locarno International Meeting onNeuroendocrinology.The Pineal Gland in Relation withthe Immune System and C ancer. Locarno, May 2-5,1 993.Lissoni P., Ardizzoia A, , Tisi E., Rossini E., B arni S. , TanciniG., Conti A., Maestroni G. J.M. (1993a) Am plification ofeosinophilia by melatonin during the immunotherapy ofcancer with interleukin-2. J. Biol. Regulat. Homeostat.Agents 7: 34-36.

Lissoni P., Barni S., Tancini G., Ardizzoia A., Rovelli F.,Cazzaniga M., Brivio F., Piperno A., Aldeghi R., FossatiD., Characiejus D., Kothari L., Conti A., Maestroni G .J.M.(1993b) Immunotherapy w ith subcutaneous low-dose in-terleukin -2 and the pineal indole melatonin as a new effec -tive therapy in advanc ed cancers of the digestiv e tract. Br.J. Cancer 67: 1404-1407.Lissoni P., Barni S., Tancini G ., Ardizzoia A., Cazzaniga M .,Frigerio F., Brivio F., Conti A., Maestroni G .J.M. (1994)Neuroimmunomodulation of interleukin-2 cancer immu-notherapy by melatonin: biological and therapeutic re-sults. Adv. Pineal Res. 7 : 183-189.Liu Z.M., Pang S.F. (1992) [ 1 2 5 ~ ]Labelled iodomelatonin bind-ing sites in the duck bursa of Fabricius: binding charac-teristics and diurnal variation. Neu rosci. Lett.146: 16 3-166 .

Lopez-Go nzalez M.A ., Calvo J.R., Osuna C., Guerrero J.M.(1992) Interaction of melatonin w ith human lymphocytes:eviden ce for binding sites coupled to potentiation of cyclicAM P stimulated by vasoactive intestinal peptide and acti-vation of cyclic G MP . J.Pinea1 Res. 12: 97-104.

Lopez-Gon zalez M.A., M artin-Cacao A., Calvo J.R., ReiterR.J., O suna C., Guerrero J.M . (1993) Specific binding of2-[ 1 2 5 ~mela tonin by partially purified mem branes of ratthymus. J. Neurimm unol. 45: 121-126.

Maestroni G.J.M. (1993) The imm unoendocrine role of me-latonin. J. Pineal. Res. 14: 1-10.

Maestroni G.J.M., Conti A. (1989) Betaend orphin and dynor-phin mimic the circadian immunoenhancing and anti-stress effects of melatonin. Int. J. Imm unopharmacol. 11:333-340.Maestroni G.J.M., Conti A. (1990) The pineal neurohormonemelatonin stimulates activated C D ~ ' ~ h ~ - l +ells to re-lease opioid ago nist (s) with imm unoenhancing and anti-stress properties. J. Neuroimm unol. 28: 167-176.

M aestroni G.J.M ., Con ti A. (1991) Anti-stress role of the me-latonin-immuno-opioid network: evidence for a physiologicalmechanism involving T-cell derived, imm unore active-en dor-phin and met-enkephalin binding to thymic opioid receptors.Intern. J. Neurosci. 61 : 289-298.

Maestroni G.J.M., C onti A., C ovacci V. (1994) Melatonin-in-duced immuno-opioids: fundamentals and clinical per-spectives. Adv . Pineal Res. 7: 73-81.

Maestroni G.J.M., Conti A., Pierpaoli W. (198 6) Role of thepineal gland in imm unity. Circadian synthesis and releaseof melatonin modulates the antibody response and anta-gonizes the imm unosuppressive effect of corticosterone. J.Neuroimmunol. 13: 19-30.

Maestroni G.J.M ., Conti A., Pierpaoli W . (1987) Role of thepineal gla nd in imm unity: 11. M elatonin enh ances the an ti-body response via an opiatergic mechanism. Clin. Exp.Immu nol. 68: 384-391.Maestroni G .J.M., Conti A,, Pierpaoli W . (1988) Role of thepineal gland in im mu nity. 111: Me latonin antagon izes theimmu nosuppressive effect of a cute stress via an opiatergicmechanism . Imm unology 63 : 465-469.

Maestroni G .J.M., Conti A., Pierpaoli W. (1989) Melatonin,stress and the immu ne system . Pineal Res. Rev. 7: 203-226 .

Maestroni G.J.M., Pierpaoli W. (198 1) Pharmacologic controlof the hormonally mediated imm une response. In: Psycho-neuroimm unology (Ed. R. Ader). Academic Press, NY, p.405-425.Martin-Cacao A., Lopez-Gonzalez M.A., Reiter R.J., CalvoJ.R., Guerrero J.M. (1993) Binding of 2-[ 1 2 5 ~melatoninby rat thymus m embranes during postnatal development.Imm unol. Lett. 36: 59-64.

Martinez d e la Escalera G., Weiner R. (1992 ) Dissociation ofdopamine from its receptor as a signal in the pleiotropichypothalamic regulation of prolactin secretion. Endoc.Rev. 13: 241-255.


16/17

McNulty J.A., Relfson M., Fox L.M., Fox L.M., Kus L.,Handa R.J., Schneider G.B. (1990) Circadian analysis ofmononuclear cells in the rat following pinealectomy andsuperior cervical ganglionectomy. Brain Behav. Im mun.4: 292-307.

Meydan i M. (199 2) Protective role of dietary vitamin E on ox-idative stress in aging. Age. 15: 89-93 .Moccheg iani E., Bulian D. , Santarelli L., Tibaldi A., M uzzioliM., Pierpaoli W., Fabris N. (1994a) The immun o-recon-stituting effect of melatonin or pineal grafting and its re-lation to zinc pool in aging mice. J. Neuroimmunol. 53:189-201.

Moccheg iani E., Bulian D., Santarelli L., Tibaldi A ., Pierpa oliW., Fabris N. (1994b) The zinc-melatonin interrelation-ship. A working hypothesis. Ann. N.Y. Acad. Sci. 719:298-307.

Morgan P.J. (1990) A novel neuroendocrine pathway regu-lates seasonal reproduction? Rowett R es. Inst. Ann.Rep.10-17.Mucha S ., ~y l i n sk aK., ~e rek -M etenG., ~wietosla wsk i . ,Stepien H. (1994) Effect of interleukin -1 on in vivo mela-tonin secretion by the pineal gland in rats. Adv. Pineal Res .7: 177-181.

Muscettola M ., Tanganelli C., Grasso G. (1994) Melatoninmodulation of interfero n- production by human p eripheralblood mononuclear cells. Adv. Pineal Res. 7: 119-123.

Niels L.P. (1989) High-affinity binding sites for melatonin inhamster spleen. Med. Sc i. Res. 17: 179-180.

Nowak J.Z., ~ u r a w s k a ., Zawilska J. (1989) Melatonin andits generating system in vertebrate retina: circadianrhythm, effect of environmental lighting and interactionwith dopamine. Neurochem. Int. 14: 397-406.Olah I. (1995) The pineal gland is a transitory lym phoid org anin the chicken. Abstracts of Con ference: Neuroendocrine-Immune-Interactions, September 8-10,199 5, Lqd ekZ dr6jnear Wroclaw, Poland.Palermo M.S ., Vermeulen M ., Giordano M. (1994) Modula-tion of antibody-dependent cellular cytotoxicity by the pi-neal gland. Adv. Pineal R es. 7: 143- 147.

Pang S .F., Yuan H., Yu Z.H ., Wang X.L., Tang P.L ., YauM.Y.C., Lee P.P.N. (1991) Melatonin binding sites in thenervous and imm une system . In: Role of melatonin and pi-neal peptides in neuroimmunom odulation (Ed. F.Fraschi-ni and R.J. Reiter). Plenum Pre ss, New York, p.107-116.Pang C .S., Pang S.F . (1992) High affinity specific binding of12 52-[ I ] odomelatonin by spleen membrane preparationsof chick en. J.Pinea1 Res. 12: 167-173 .Persegniev S.P., Kyurkchiev S . (1>33) Selective effect of me-latonin on the proliferation of lymphoid cells. Int. J.Biochem. 25: 441-444.

PCvet P. (1985) 5-methoxyindoles, pineal, and seaso nalrepro -duction - a new approach. In: The pineal gland. Currentstate of pineal research ( Eds. B.Mess, C s.Ruzsas, L.Timaand P.Pevet ) Akadmiai Kiado, Budapest, p. 163-186.

Pierpaoli W ., Maestroni G.J.M . (1987) Melatonin: a principalneuroimm unoregulatory and anti-stress hormone: its anti-aging effects. Imm unol. Lett.16: 3 55-362.Pierpaoli W., Yi C. (1990) The invo lvement of pineal gland

and melatonin in immunity and aging. 1.Thymus -medi-ated, immu norec onstituting and antiviral activity of thyro-tropin-releasing hormone. J. Neuroim munol. 27: 99-10 9.Poon A.M.S., Liu Z .M., Tang F., Pang S.F. (1994) Cortisol de-creases 2-[ 1 2 5 ~ iodomelatonin binding sites in the duckthymus. Eur. J. Endocrinol. 130: 320-324.Poon A.M.S., Pang S.F. (1992a) 2-[ 1 2 5 ~ ]odomelatonin bind-ing sites in spleens of guinea pigs. Life Sci . 50: 17 19-17 26.

Poon A.M.S., Pang S.F. (1992b) Constant light exposure in-creases 2-[ 1 2 5 ~iodomelatonin binding sites in the guineapig spleen . Neurosci. Lett. 146: 41-44 .Poon A .M.S., Pang S.F. (1994a) Modulation of 2-[ 1 2 5 ~ io-domelatonin binding sites in the guinea pig spleen byguanine nucleotides and cations. Neuroendocrinology 59:156-162.Poon A.M .S., Pang S.F. (1994b) Modulation of 2-[ 1 2 5 ~ io-dom elatonin binding sites in the guinea pig spleen by me-latonin injection is dependent on the dose and period butnot the time. Life Sci. 54: 1441-1448.

Poon A .M.S., Wang X .L., Pang S.F. (1993) Characteristics of2- [ 1 2 5 ~iodomelatonin binding sites in the pigeon spleenand modu lation of binding by guanine nucleotides. J. Pi-neal Res. 14: 169-177.Raffi-ElIdrissi M., C alvo J.R., Pozo D., Sharmouch A., Guer-rero J.M. (1995) Sp ecific binding of 2-[ 1 2 5 ~ iodomela-tonin by rat splenocytes: Characterisation and its role onregulation of cyclic AMP production. J. Neuroimmunol.57: 171-178.

Reiter R.J. (1989) The pineal and its indole products : basic as-pects and clinical applications. In: The brain as an en do-crine organ (Eds. M.P.Cohen and P.P.Foley). Springer,Vienna, p. 96- 149.Reiter R.J. (1993a) A review of neuroendocrine and neuro-chemical changes associated with static andex treme ly lowfrequency electromagnetic field exposure. Integrat. Physi-01. Behav. Sci. 28: 57-7 5.Reiter R.J. (1993b) The melatonin rhythm: both a clock anda callendar. Experientia 49: 654-66 4.Reiter R.J. (1994) Impact of the electromagnetic environmenton the neurohormone m elatonin. Biometeorology 1: 135-153.

Reiter R.J., Richardson B.A . (1992) Magnetic field effects onpineal indoleamine metabolism and possible biologicalconsequences. FASEB J. 6: 2283-2287.

Reiter R.J., Tan D., Poeggeler B., Chen L., Menendez-PelaezA. (1994) M elatonin, free radicals and cancer initiation.Adv. P ineal Res. 7: 21 1-228.Rodriguez A.B., Lea R.W. (1994) Effect of pinealectomyupon the nonspecific immun e response of the ring-dove(Streptopelia risoria). J. Pineal Res. 16: 159-166.


17/17

Pineal-immune interrelationships 357Rosolowska-Huszcz D ., Thaela M.-J., Jagura M., Stepien D.,Skwarlo-Sonta K . (1991) Pineal influence on the diurnalrhythm of nonspecific immunity indices in chickens. J. Pi-neal Res. 10: 190-195.Seeman T.E., Robbins R.J. (1994) Aging and hypothalam ic-pituitary-adrenal response to challenge in hu mans. Endo-crine Rev. 15: 233-260.Skwarlo-Sorita K. (1992) Minireview: Prolactin as an imm u-noregulatory hormone in mammals and birds. Immunol.Lett. 33: 105-122.Skwarlo-Sodta K., Raczydska J., Zujko J., Koziowska E.,Gladysz A., Laskowska H., Drela N. (19 94a) Lack of theanti-glucocorticoid activity of melatonin in chicken im-mune system . Adv. Pineal Res. 7: 137-142.Skwarlo-Sonta K., Rosoiowska-Huszcz D., Sidorkiewicz E.(1983) Diurnal changes in certain immunity indices and

plasma corticosterone concentration in White Leghornchickens. Acta Physiol. Pol. 34: 445-456.Skwario-Sorita K., So towska-B rochocka J . , Rosolowska--Huszcz D., Pawowska-Wojew6dka E., Gajewska A.,Stepien D., Kochman K . (1987) Effect of prolactin on thediurnal changes in immune parameters and plasma corti-costerone in White Leghorn chickens. Acta Endocrinol.(Copenh). 116: 172-178.Skwarlo-Sodta K., Thaela M.-J., Gluchowska B ., Stepien D.,Jagura M. (1991) Effect of dose and time of melatonin in-jections on the diurnal rhythm of immunity in chicken. J.Pineal Res. 10: 30-35.Skwario-Solita K., Thaela M.-J . , Midura M., Lech B.,Giu chow ska B., Drela N., Kozlowska E., Kowalczyk R.(1992) Exogenous melatonin modifies the circadianrhythm but does not increase the level of some immuneparameters in the chickens. J. Pineal Res. 12: 27-34.Skwarlo-Sorita K., Woliriska-Witort E., Dziwiriski T., S nochowskiM., Sotowska-Brochocka J. (1994b) Melatonin bindingsites in chicken lymp hoid glands, gonads and central nerv-ous system. Acta Neurobiol. Exp . 54 (Suppl.): 1 32-133.Song Y., Ayre E.A., Pan S.F. (1992) The identification andcharacterization of 1551-labelled iodom elaton in-bin dingsites in the duck kidney. J. Endocrinol. 135: 353-359.Smith E.M., Blalock J.E. (198 1) Hum an lym phocyte productionof ACTH an endorphin-like substances: Association withleukocyte interferon. Proc. Natl. Acad. Sci. 78: 7530-7534.Stankov B., Reiter R.J. (1990) M inireview. Melatonin recep-tors: current status, facts, and hypotheses. Life Sci. 46:971-982.

Van de Kar L.D., Richardson-Morton K .D., Rittenhouse P.A.(1991) Stress: neuroendocrine and pharmacologicalmechanism s. In: Stress revisited. 1. Neuroendocrinologyof stress (E ds. G. Jasmin and M. Ca nti n). S. Karger, Basel,p. 133-173.Verm eulen M. , Palermo M ., Giordano M. (1993) Neonatal pi-nealectomy impairs murine antibody-dependent cellularcytotoxicity. J. Neuroimm unol. 43: 97-102.Wang Z.P., Cheng K.M., Brown G.M., Pang C.S.-F., PangS.F. (1992) Characterization of 2-[125~]iodomelatonin-binding sites in quail testes at mid-light and mid-dark.Neurosci. Lett. 146: 195-198.Wan X.L., Yuan H., Pang S.F. (1993) Specific binding of[851]iodomelatonin in pigeon and quail spleen membranepreparations and effect with hydrocortisone-treatment.Acta Pharmacol. Sin. 14: 292-295.Withyach umnarnk ul B., Nonaka K.O., Attia A.M., Reiter R.J.(1990a) Changes in indole metabolism in organ culturedrat pineal glands induced by interferon-y. J. Pineal Res. 8:313-322.Withyachumnarnkul B., Nonaka K.O., Santana C., AttiaA.M ., Reiter R.J. (1990b) Interferon- modulates melatoninproduction in rat pineal glands in organ cultu re. J. Interfe-ron Res. 10: 403- 41 1.Withyachumnarnkul B., Reiter R., Lerchl A., Nonaka K.O.,Stokkan K .-A. (1991 ) Evidence that interferon-y alters pi-neal metabolism both indirectly via sym pathetic nerves and

directly on the pinealocytes. Int. J. Biochem. 23: 1 397-1401.Wy bran J. (1985) Enkephalins and endorphins as modifiers ofthe imm une system: present and future. Federation Proc.44: 92-94.Yu Z.-H., Yuan H., Lu Y., Pang S.F. (1991) [125~ ]~od om ela-tonin binding sites in spleen s of birds and mammals. Neu-rosci. Lett. 125: 175-178.zylin ska K., Komorowski J., Robak T., Mucha S ., Stepied H.(1995) Effect of granulocyte-macrophage colony stimu-lating factor and granulocyte colony stim ulating factor onmelatonin secretion in rats . n vivo an d in vitro studies. J.Neuroimmunol. 56: 187-190.

Paper presented at the 2nd International Congres of thePolish Neuroscience Society; Session: Melatonin: o rigin andfunctions in an organism

Documents

Functional connections between the pineal gland and immune system