Psychiatry Research, 41: 17-24 Elsevier

Dopamine Uptake by Platelets From Subjects With Schizophrenia: A Correlation With the Delusional of the Patient

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State

Brian Dean, Jayashri Kulkarni, David L. Copolov, Preethi Shrikanthan, Valcy Malone, and Christine Hill

Received July 9, 1991; revised version received October 31, 1991; accepted November 17, 1991.

Abstract. The uptake of 3H-dopamine by platelets from patients with a number of psychiatric disorders has been compared with that by platelets from normal volunteers. Overall, 3Hdopamine uptake by platelet-rich plasma (PRP) from 25 schizophrenic subjects did not differ from 3Hdopamine uptake by PRP from 22 nonschizophrenic patients and 61 normal volunteers. In the schizophrenic group, however, there was an increased spread of results with seven values falling outside the range of results observed in the control group. Furthermore, of the patients rated, only for the schizophrenic patients was there an inverse correlation between 3H-dopamine uptake by platelets and the rating for delusions on the Scale for the Assessment of Positive Symptoms. Thus, 3H-dopamine uptake by platelets seems, in some way, to be linked to the delusional state of the patient. Further study of 3H-dopamine uptake by platelets is warranted in a larger and more diverse group of patients to determine the significance of altered dopamine uptake by platelets from some schizophrenic subjects and the correlation between platelet 3H-dopamine uptake and the delusional state of these subjects.

Key Words. Platelets, dopamine uptake, Alzheimer’s disease, schizophrenia.

Dopamine uptake by platelets from some subjects with schizophrenia has been shown to be altered when compared with uptake by platelets from control subjects (Rotman et al., 1980; Shah et al., 1982; Dean et al., 1990). In an attempt to determine the prevalence and specificity of altered dopamine uptake by platelets, we measured the uptake of 3H-dopamine by platelet-rich plasma (PRP) from patients admitted to Royal Park Hospital (RPH) and from normal volunteers. Furthermore, to determine if the change in dopamine uptake by platelets was associated with particular symptoms, instead of with a disorder, we compared platelet

Brian Dean, H.N.D. App. Biol., M.I. Biol., C.I. Biol., M.Sc., is Head of the Neurochemistry Section of the Mental Health Research Institute of Victoria and an Associate Investigator of the National Health and Medical Research Council Schizophrenia Research Unit at Royal Park Hospital. Javashri Kulkarni. M.B., B.S., F.R.A.N.Z.C.P., is a C&sultant Psychiatrist at Roial Park Hospital and an Associate Investigator of the NH&MRC Schizouhrenia Research Unit. David Couolov. MB.. B.S.. Ph.D.. D.P.M.. M.P.6, F.R.A.N.Z.C.P., is the Dirkctor of the Mental Health Research institute of i’ictoria and Co: Director of the NHBMRC Schizophrenia Research Unit. Preethi Shrikanthan is a Technical Assistant at the Mental Health Research Institute of Victoria. Valcy Malone, R.N., and Christine Hill, B.A., R.P.N., G.D.A.C.P., are Research Assistants at the Mental Health Research Institute of Victoria. (Reprint requests to Dr. B. Dean, Mental Health Research Institute of Victoria, Private Bag 3, Parkville, Victoria 3052, Australia.)

0165-1781/92/$03.50 @ 1992 Elsevier Scientific Publishers Ireland Ltd.

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dopamine uptake with ratings from a number of symptomatological rating scales.

Methods

Blood was obtained from consenting neuroleptic-free patients admitted to RPH and from medication-free volunteers. Patients were deemed neuroleptic free if they had not received neuroleptic drugs orally for 1 month or by depot injection for 3 months before blood collection. In addition, any subject identified as taking drugs known to affect platelet function (e.g., aspirin) within 3 weeks of the blood donation was also excluded from the study. On the basis of these criteria, 47 patients and 61 normal volunteers were recruited for the study.

At the time of blood collection, one of two experienced psychiatric nurses rated patients who did not have the provisional diagnosis of Alzheimer’s disease, using the Brief Psychiatric Rating Scale (BPRS; Overall and Gorham, 1962) and the Scales for the Assessment of Positive (SAPS) and Negative (SANS) Symptoms (Andreasen and Olsen, 1982). Diagnosis was made after a case history review and by DSM-ZZZ criteria (American Psychiatric Association, 1980).

Of the 47 patients in the study, 10 were diagnosed as paranoid schizophrenia (7 male/3 female), 11 as undifferentiated schizophrenia (9 male/2 female), 3 as residual schizophrenia who were chronic with acute exacerbation (3 male), and 1 as disorganized schizophrenia (1 male). The nonschizophrenic patients consisted of 12 subjects with the provisional diagnosis of Alzheimer’s disease (7 male/5 female) and 10 subjects with a number of diagnoses (Table 1). The normal volunteers consisted of 29 males and 32 females made up of 28 staff members of the Mental Health Research Institute, 10 staff members from RPH, and 23 individuals recruited from other sources. There were no significant differences in the ages of the schizophrenic subjects and the control subjects (schizophrenic subjects: mean age = 35 years, SD = 10; control subjects: mean age = 35 years, SD = 14; p = NS). The mean age of the nonschizophrenic patients (mean age = 51 years, SD = 25; p < 0.01) was higher than that of the normal volunteers because of the inclusion of subjects with the provisional diagnosis of Alzheimer’s disease (mean age = 72 years, SD = 9; p < 0.001).

The uptake of 3H-dopamine by PRP was measured as described previously (Dean et al., 1990). Briefly, venous blood was collected from subjects between 9 and 11 a.m. and mixed (9 vol to 1 vol) with 26.9 mM EDTA in 17.1 mM sodium chloride. After centrifugation of the blood at 800g for 15 minutes at 4 ‘C, the supernatant of PRP was collected and the number of platelets in each PRP counted. Aliquots (250 ,~tl in triplicates) of PRP were then incubated at 37 “C for 10 minutes before the addition of sH-dopamine (50 ~1: final concentration 9 nM) and the uptake of 3Hdopamine was measured after a further incubation at 37 ‘C for 10,30, or 60 min. To obtain an integrated value of dopamine uptake by PRP over time, the area under

Table 1. Clinical details of subjects recruited to be studied who were not diagnosed as schizophrenic

Diaanosis Sex

Bipolar mood disorder, manic

Organic mental disorder

Borderline personality disorder

Adjustment disorder

Bipolar affective disorder, manic

Antisocial personality disorder

Paranoid delusional disorder

Posttraumatic stress disorder

Major depressive episode

Alzheimer’s disease

2M

M

M

M

M

M

M

M

F

7Mi5F

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the dopamine uptake curve to 60 minutes (AUDC) was then calculated and expressed in arbitrary units (Arb. Units) (Dean et al., 1990).

One-way analysis of variance, least squares best fit regression, and correlation coefficients were calculated using the Minitab statistical program.

Results

The uptake of sH-dopamine by PRP from female and male normal volunteers did not differ (females: mean = 138 Arb. Units, SD = 120; males: mean = 151 Arb. Units, SD = 79; p = NS) and did not correlate with the age of the donor (r = 0.01). Thus, dopamine uptake by PRP from the patients was compared .to a reference range of 59 to 455 Arb. Units established from the results from all volunteers instead of comparing patient results with those from age- and sex-matched controls.

As a whole, the uptake of 3H-dopamine by PRP from schizophrenic subjects and normal volunteers did not differ (Fig. 1 and Table 2). However, the uptake of 3H-dopamine by PRP from the three residual schizophrenic subjects was significantly higher than that by PRP from the normal controls, the nonschizo- phrenic subjects, and the nonresidual schizophrenic subjects (Table 2). By contrast, the uptake of 3H-dopamine by PRP from the nonresidual schizophrenic group tended to be lower than that by PRP from the normal volunteers, but these differ- ences did not reach significance. In fact, 3H-dopamine uptake by PRP from six of

Fig. 1. Uptake of 3H-dopamine by platelet-rich plasma from schizophrenic subjects, nonschizophrenic subjects, and normal volunteers

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Table 2. 3H-dopamine uptake (mean f SD) by platelet-rich plasma from subjects with schizophrenia, subjects admitted to Royal Park Hospital who were not diagnosed as schizophrenic, and subjects with the provisional diagnosis of Alzheimer’s disease

3H-dopamine uptake Subjects (area under uptake curve) I)

Normal volunteers 143+ 83

Schizophrenic 139~111

Residual 402 +- 104

Nonresidual 104+ 49

Nonschizophrenic 149+ 68

Alzheimer’s disease 158+ 81

Others 139* 49

NS

p < 0.001

p < 0.051

NS

NS

NS

these subjects (5 undifferentiated, 1 paranoid) was lower than that by any PRP from the nonschizophrenic patients and the normal volunteers.

Total BPRS scores of the schizophrenic subjects were higher than those for the nonschizophrenic patients who were rated (schizophrenic subjects: mean = 28.6, SD = 8.0; nonschizophrenic patients: mean = 19.8, SD = 9.4; p < 0.01). The higher BPRS score was primarily the result of the schizophrenic subjects being rated significantly higher for thought disorder and because they tended to be rated higher for anxiety and depression as well as anergia. The schizophrenic patients also had a higher total SAPS rating than did the nonschizophrenic patients (schizophrenic patients: mean = 47.6, SD = 24; nonschizophrenic patients: mean = 30.2, SD = 20; p < 0.05) due mainly to a higher rating of delusions (schizophrenic patients: mean = 23.5, SD = 13; nonschizophrenic patients: mean = 12.6, SD = 7.8;~ = 0.016). The total SANS ratings for the schizophrenic and nonschizophrenic patients did not differ significantly despite a significantly higher rating of attentional impairment in the schizophrenic group (schizophrenic patients: mean = 5.0, SD = 4.5; nonschizo- phrenic patients: mean = 1.5, SD = 3.5; p < 0.05).

There were significant correlations between the uptake of 3H-dopamine by PRP from the schizophrenic patients and their BPRS rating of anergia (r = 0.67, p < 0.001) SAPS rating of delusions (r = -0.6,~ < 0.001) (Fig. 2), SANS total rating (r = 0.62, p < O.OOl), and SANS ratings of affective flattening (r = 0.65,~ < 0.001) alogia (r = 0.62, p < O.OOl), and avolition and apathy (r = 0.44, p < 0.05). Such correlations were not observed in comparisons of 3H-dopamine uptake by PRP and psychopathological ratings from the nonschizophrenic/non-Alzheimer’s disease patients.

PRP from the patients with residual schizophrenia took up significantly more 3H-dopamine than did PRP from those with nonresidual schizophrenia. Thus, in case the inclusion of the low number of residual schizophrenic patients was causing Type 1 errors (i.e., correlations were due to the presence of these three patients in the schizophrenic group), the uptake of 3H-dopamine by PRP from the 22 subjects with nonresidual schizophrenia was compared with the ratings from the BPRS, SAPS, and SANS. In that instance, a better correlation (r = -0.77, p < 0.001; Bonferroni

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adjusted p < 0.0029 is significant) with the SAPS ratings for delusions was apparent (Fig. 2), but no other correlations were observed. Therefore, the relationship between platelet dopamine uptake and delusion ratings in this group of patients would not seem to be due to chance or a Type 1 error.

Fig. 2. Relationship between uptake of 3H-dopamine by PRP from residual (diamonds) and nonresidual (circles) schizophrenic subjects to SAPS delusions rating as described by least squares best fit regression line for all subjects (solid line) and nonresidual schizophrenic subjects (dashed line)

;i 5 : 450-

0 400- l

; 350- . l

g 300

+ 250

g 200

f ;!!I :A

8 0 f P I 0 10 20 30 40 50 = SAPS : Delusions rating

PRP = platelet-rich plasma. SAPS = Scale for the Assessment of Positive Symptoms.

Discussion

Our findings, like those of Rotman et al. (1980) but not Shah et al. (1982), show the uptake of 3H-dopamine by platelets from some subjects (27 and 25% respectively) with schizophrenia to be decreased. However, overall there was no significant difference between 3H-dopamine uptake by platelets from schizophrenic and nonschizophrenic subjects. Significantly, in this study, the lowest uptake of 3H- dopamine was by platelets from two schizophrenic subjects who were on their first admission and had never received neuroleptic drugs, suggesting these changes to be pathophysiological.

The uptake of 3Hdopamine by PRP from the three residual schizophrenic subjects, who had received repeated neuroleptic treatments, was significantly higher (mean = 402, SD = 64) than that by PRP from the other schizophrenic subjects (mean = 104, SD = 49; p < 0.001). This increased dopamine uptake by platelets from the residual patients, as well as the increased dopamine uptake by platelets from schizophrenic patients being treated with neuroleptics observed by Shah et al. (1982), could therefore be due to an effect of neuroleptic drug treatment. Such changes could arise because of a specific increase in the numbers of dopamine uptake mechanisms on the platelet due to the effects of neuroleptic drugs which have been shown to increase expression of proteins other than dopamine receptors (Dragunow et al., 1990). On the other hand, it could be part of a generalized effect of neuroleptic

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drugs because of their ability to increase total protein synthesis in a cell (Nimgaonkar and Whatley, 1990).

All but one of the correlations between dopamine uptake by platelets and patient ratings failed to reach significance when only results for nonresidual schizophrenic subjects were compared. This would suggest that five of the six correlations might be arising as a result of Type 1 errors due to the examination of a combination of the residual and nonresidual patients.

It has been suggested (Drummond, 1976) that the interaction of biogenic amines with the platelet models similar interactions with neurons. If that is the case, then neuronal dopamine uptake may be decreased in a subpopulation of schizophrenic subjects and it would seem possible that the resulting increase in extraneuronal dopamine would worsen psychoses by increasing dopaminergic neuronal activity. Such a hypothesis would be supported by the observation that drugs such as methylphenidate (Davis, 1974), cocaine (Bowman et al., 1971), and phencyclidine (Junien and Leonard, 1989), which reduce neuronal dopamine transport, cause or worsen psychoses in both schizophrenic and nonschizophrenic subjects. On the other hand, if altered neuronal dopamine uptake were involved in the pathophysiology of schizophrenia, then changes in the dopamine uptake mechanisms in brain tissue from schizophrenic subjects should be detectable. However, while some studies report alterations in the dopamine uptake sites in autopsied brain tissues from schizophrenic subjects (Haberland and Hetey, 1987; Chinaglia et al., 1990) others could not show significant changes (Pearce et al., 1990). Thus, a possible role for alterations in neuronal dopamine uptake as a cause of psychosis in schizophrenia remains to be established.

The platelet dopamine uptake system has been shown to consist of a high affinity, low capacity mechanism and a low affinity, high capacity system (Dean and Copolov, 1989). In measurements of dopamine uptake by platelets at low concentra- tions, as in this study, it is likely that the uptake measured would be by the high affinity system. In addition to the well-characterized low affinity, high capacity neuronal dopamine uptake mechanism, a high affinity, low capacity neuronal dopamine uptake mechanism has recently been identified in murine brain tissue (Efthimiopolous et al., 1991). If this uptake mechanism is present in the human brain, it may more closely resemble the dopamine uptake mechanism of the platelet than does the low affinity uptake mechanism. In that case, it seems possible that changes in that neuronal dopamine uptake mechanism could be involved in causing some of the symptoms of schizophrenia.

In Parkinson’s disease, reports of decreased dopamine uptake by platelets (Barbeau et al., 1975) preceded the clear demonstration of decreased dopamine transport sites in the brain tissue (Pimoule et al., 1983; Pearce et al., 1990). By contrast, the significance of the finding of decreased dopamine uptake by platelets from some subjects with schizophrenia remains to be determined. However, further study of the changes in dopamine uptake by platelets from schizophrenic subjects is warranted. These studies should examine dopamine uptake by platelets from more diverse groups of patients to determine the specificity of decreased dopamine uptake by platelets from some subjects with schizophrenia. Furthermore, the effect of neuro- leptic treatment on dopamine uptake by platelets should be determined to discover if

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the differences between dopamine uptake by platelets from residual and nonresidual schizophrenic patients could be due to drug treatment. Finally, dopamine uptake by platelets should be measured on hospital admission and after improvement in symptoms to determine whether altered dopamine uptake by platelets is state or trait dependent.

Acknowledgments. This work was supported in part by grants-in-aid by the Rebecca Cooper Medical Research Foundation, the Helen M. Schutt Trust, and the William Buckland Foundation.

References

American Psychiatric Association. DSM-ZZZ: Diagnostic and Statistical Manual of Mental Disorders. 3rd ed. Washington, DC: Author, 1980.

Andreasen, N.C., and Olsen, S. Negative v positive schizophrenia. Archives of General Psychiatry, 39:789-794, 1982.

Barbeau, A.; Campanella, G.; Butterworth, R.F.; and Yamada, K. Uptake and efflux of r4C-dopamine in platelets: Evidence for a generalized defect in Parkinson’s disease. Neurology, 25: 1-9, 1975.

Bowman, W.C.; Rand, M.J.; and West, G.B. Textbook of Pharmacology. Oxford: Blackwell Scientific Pub., 1971.

Chinaglia, G.; Alvarez, J.; Probst, A.; and Palacios, J.M. Autoradiographic visualization of neurotransmitter uptake sites in human post-mortem material. (Abstract #PD5) Proceedings of the International Presynaptic Receptor and Neural Transmission, 1990. p. 87.

Davis, J.M. A two factor theory of schizophrenia. Journal of Psychiatric Research, 11:25- 29, 1974.

Dean, B., and Copolov, D.L. Dopamine uptake by platelets is selective, temperature dependent and not influenced by the dopamine-D, or dopamine-D, receptor. Life Sciences, 45:401-411, 1989.

Dean, B.; Kulkarni, J.; and Copolov, D.L. Validation of a method to measure the uptake of 3H-dopamine by human platelets. Clinica Chimica Acta, 187:37-46, 1990.

Dragunow, M.; Williams, M.; and Faull, R.L.M. Haloperidol induces Fos and related molecules in intrastriatal grafts derived from fetal striatal primordia. Brain Research, 530:309- 311,199o.

Drummond, A.H. Interactions of blood platelets with biogenic amines: Uptake, stimulation and receptor binding. In: Gordon, J., ed. Platelets in Biology and Pathology. Amsterdam: Elsevier Science Publishers, 1976. pp. 203-239.

Efthimiopolous, S.; Giompres, P.; and Valcana, T. Kinetics of dopamine and noradrenaline transport by synaptosomes from cerebellum, striatum and frontal cortex of normal and reeler mice. Journal of Neuroscience Research, 295 1 O-5 19, 199 1.

Haberland, N., and Hetey, L. Studies in post-mortem dopamine uptake: II. Alterations of the synaptosomal catecholamine uptake in post-mortem brain regions in schizophrenia. Journal of Neural Transmission, 68:303-313, 1987.

Junien, J.L., and Leonard, B.E. Drugs acting on sigma and phencyclidine receptors: A review of their nature, function, and possible therapeutic importance. Clinical Neuropharma- cology, 12:353-374, 1989.

Nimgaonkar, V.L., and Whatley, S.A. A specific effect of antipsychotic drugs on protein synthesis in human lymphomononuclear cells. Journal of Neurochemistry, 54: 1934-1940, 1990.

Overall, J.E., and Gorham, D.R. The Brief Psychiatric Rating Scale. Psychological Reports, 10:799-812, 1962.

Pearce, R.K.B.; Seeman, P.; Jellinger, K.; and Tourellotte, W.W. Dopamine uptake sites and dopamine receptors in Parkinson’s disease and schizophrenia. European Neurology, 3O(Suppl. 1):9-14, 1990.

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Pimoule, C.; Schoemaker, H.; Javoy-Agid, F.; Scatton, B.; Agid, Y.; and Langer, S.Z. Decreases in 3H-cocaine binding to the dopamine transporter in Parkinson’s disease. European Journal of Pharmacology, 95:145-146, 1983.

Rotman, A.; Munitz, H.; Modai, I.; Tjano, S.; and Wijsenbeek, H. A comparative uptake study of serotonin, dopamine, and norepinephrine by platelets of acute schizophrenic patients. Psychiatry Research, 31239-246, 1980.

Shah, N.S.; Burch, E.A.; Pressley, L.C.; Rausch, J.L.; Chestnut, E.; and Donald, A.G. Platelet uptake of dopamine in patients with schizophrenia. Research Communications in Psychiatry, Psychology, and Behavior, 7:489-492, 1982.