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Abstract. Background and Objectives:Mobile phone radiation and health concerns havebeen raised, especially following the enormousincrease in the use of wireless mobile telephonythroughout the world. The present study aims toinvestigate the effect of one hour daily exposureto electromagnetic radiation (EMR) with frequen-cy of 900 Mz (SAR 1.165 w/kg, power density 0.02mW/cm2) on the levels of amino acid neurotrans-mitters in the midbrain, cerebellum and medullaof adult and young male albino rats.

Materials and Methods: Adult and youngrats were divided into two main groups (treatedand control). The treated group of both adult andyoung rats was exposed to EMR for 1 hour daily.The other group of both adult and young ani-mals was served as control. The determinationof amino acid levels was carried out after 1 hour,

1 month, 2 months and 4 months of EMR expo-sure as well as after stopping radiation.

Results: Data of the present study showed asignificant increase in both excitatory and in-hibitory amino acids in the cerebellum of adultand young rats and midbrain of adult animals af-ter 1 hour of EMR exposure. In the midbrain ofadult animals, there was a significant increase inglycine level after 1 month followed by significantincrease in GABA after 4 months. Young ratsshowed significant decreases in the midbrain ex-citatory amino acids. In the medulla, the equilibri-um ratio percent (ER%) calculations showed astate of neurochemical inhibition after 4 months

in case of adult animals, whereas in young ani-mals, the neurochemical inhibitory state was ob-served after 1 month of exposure due to signifi-cant decrease in glutamate and aspartate levels.This state was converted to excitation after 4months due to the increase in glutamate level.

Conclusion: The present changes in aminoacid concentrations may underlie the reportedadverse effects of using mobile phones.

Key Words:

Electromagnetic radiation, Amino acid neurotrans-

mitters, Midbrain, Cerebellum, Medulla.

European Review for Medical and Pharmacological Sciences

Variations in amino acid neurotransmitters insome brain areas of adult and young male albino

rats due to exposure to mobile phone radiationN.A. NOOR, H.S. MOHAMMED*, N.A. AHMED, N.M. RADWAN

Zoology Department, Faculty of Science, Cairo University, Cairo (Egypt) *Biophysics Department,Faculty of Science, Cairo University, Cairo (Egypt)

Corresponding Author:Neveen A. Noor, MD; e-mail: neveen.nour5@gmail.com 729

Introduction

Mobile phone radiation and health concerns

have been raised, especially following the enor-mous increase in the use of wireless mobile tele-phony throughout the world. Mobile telephoneantennae emit low level radiofrequency (RF)electromagnetic fields in the microwave rangewith wavelength frequency band starting fromabout 900 MHz1.

Low-frequency magnetic field induces circu-lating currents within the human body. Thestrength of these currents depends on the intensi-ty of the outside magnetic field. If sufficientlylarge, these currents could cause stimulation of

nerves and muscles or affect other biologicalprocesses2. Due to the close proximity of the mo-bile phone device to the head, the human brain isexposed to relatively high specific absorptionrates (SARs) compared to the rest of the body3.However, it has been reported that different brainregions could respond differently to radiofre-quency radiation (RFR)4.

It has been indicated that an electromagneticfield influences the biological functions of nervecells and induces changes in neurotransmittercontents5. The efflux of calcium ions from braintissue is an important neurochemical effect of

RFR as calcium ion plays an important role inthe functions of the nervous system such as therelease of neurotransmitters6.

Many hazardous effects on the nervous systemhave been described due to electromagnetic field(EMF) of digital mobile phone. EMF emittedfrom mobile phone could affect sleep7, learningand memory8,9 , attention10, cognitive perfor-mance11, headache12 and disturbances in bloodbrain barrier permeability13,14. Recently, distur-bances in the hypothalamic15, thalamic and stri-atal16 amino acid neurotransmitters after short-

and long-term exposure to electromagnetic radia-

2011; 15: 729-742

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tion (EMR) were reported. Moreover, Khadrawyet al.17 suggested that the changes in corticalamino acid neurotransmitters due to EMR expo-sure may underlie the EMR-induced changes incortical excitability. However, the influence ofmobile phones on heart rate and blood pressure isstill problematic18,19. Furthermore, Balik et al.20

indicated that there is no effect on redness of theeyes and vision disturbance, but some statisticalevidences indicated that mobile phone may causeblurring of vision, secretion, inflammation andlacrimation of the eyes.

The present study aims to investigate the vari-ations in amino acid neurotransmitters in themidbrain, cerebellum and medulla of adult andyoung male albino rats due to their exposure to

electromagnetic radiation (EMR) at a frequencyof 900 MHz, power density of 0.02 mW/cm2 andSAR of 1.165 W/kg. The study also extended toinvestigate the status of amino acid neurotrans-mitters after stopping exposure to EMR.

Materials and Methods

Experimental AnimalsThe experimental animal used in this study is

the male albino rat. Both young (one month old)and adult (four months old) animals were usedand provided with food and water ad libitum. Allexperiments were carried out in accordance withresearch protocols established by the AnimalCare Committee of the National Research Cen-ter, Egypt.

Electromagnetic Exposure Setup

The EMR exposure system and method of ex-posure were described previously by Khadrawy

et al17.

Experimental DesignAdult and young rats were divided into two

main groups (treated and control). The 1st groupof both adult and young rats was exposed toEMR (frequency 900 MHz, power density 0.02mW/cm2 and average SAR 1.165 W/kg) simulta-neously for 1 hour daily. The 2nd group of bothadult and young animals was placed at the sametime in a similar container for 1 hour away fromthe RF source and served as control animals. A

subgroup from each treated and control animals

was sacrificed after 1 hour, 1 month, 2 monthsand 4 months of daily exposure. Another sub-group from the treated animals (adult and young)was left for 1 month without exposure (after 4months of daily exposure) to study the withdraw-al effect of the radiation and were then sacrificedwith a group of the control animals. The numberof treated and control rats were listed in the Ta-bles of results between parentheses.

The animals were killed by sudden decapita-tion and brain areas were dissected out, weighedand kept frozen until analyzed.

Reagents and ChemicalsAbsolute ethyl alcohol (Riedel, Darmstadt,

Germany) was used for homogenization. Lithium

carbonate (Merck, Darmstadt, Germany), dansylchloride (Sigma, St. Louis, MO, USA) andHPLC grade acetonitrile (Hypersolv, BDHChemicals, Ltd., Poole, Dorset, UK) were usedfor dansylation. Free amino acids and their dan-syl derivatives were purchased from BDH Chem-icals, Ltd. (Poole, Dorset,UK). HPLC grademethanol (Riedel, Darmstadt, Germany), synthe-sis grade triethylamine (Merck, Darmstadt, Ger-many) and deionized water were used to preparethe mobile phase.

Determination of AminoAcid ConcentrationsThe method applied in this study was based on

HPLC method employed by Mrquez et al.21

with some modification for application to braintissue22. Each brain area was homogenized in 3ml ethyl alcohol (75%). Two other ml was usedto rinse the homogenizer (Heidolph DIAX 900,Germany). The precipitated protein was removedby centrifugation at 12000 r.p.m. (21.036 g) for30 minutes at 4C using a high speed coolingcentrifuge (Type 3K-30, Sigma, Osterode-am-Harz, Germany). The clear supernatant was evap-

orated to dryness and stored at -80C.

Dansylation ReactionDansyl derivatization was carried out accord-

ing to the method of Tapuhi et al.23, using Dns-Clin acetonitrile and a 40 mM lithium carbonate so-lution (pH. 9.5) as a reaction buffer.

ChromatographyThe HPLC system consisted of a Wellchrom

Mini-star K-501 pump (Knauer, Berlin, Ger-many), a column thermostat 5-85C with injector

equipped with a 10 l loop (Knauer, Berlin, Ger-

N.A. Noor, H.S. Mohammed, N.A. Ahmed, N.M. Radwan

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in adult rats showed a significant decrease afterone month that was reversed to significant in-crease after two months of EMR radiation. How-ever, taurine levels in young rats showed signifi-cant increases after one hour and two months ofexposure to EMR.

Glutamic and aspartic acid levels in themedulla of young rats (Table V) recorded signifi-cant decreases after one and two months of radia-tion. Meanwhile, as recorded in Table VI, the in-hibitory amino acid, GABA showed general in-crease throughout the experimental periods inadult rats.

Stopping of EMR exposure revealed signifi-cant decreases in glutamine levels in the mid-brain of both adult and young rats (Table I). In

the cerebellum of young animals, a concomitantsignificant increase in aspartic acid (Table III)and GABA levels (Table IV) was observed afterstopping exposure. In addition, cerebellar gluta-mine content showed significant decrease inadult rats (Table III). In the medulla of young an-imals, significant increases in glutamate (TableV) and GABA (Table VI) combined with signifi-cant decrease in glutamine level were observedafter stopping exposure to EMR.

Discussion

The emission of low-level radiofrequencyelectromagnetic field leading to the absorption ofradiation by the brain in users of handheld mo-bile phones has raised concerns regarding poten-tial effects on health24.

The present data showed a rapid significant in-crease in both excitatory and inhibitory aminoacids in the cerebellum of adult and young ratsafter 1 hour of EMR exposure. This effect wasalso prominent in the midbrain of adult animals

only.It has been proven that both pulse-modulated

and continuous RF-EMR including those ofGSM have the potency to significantly increasethe permeability of the blood brain barrier13,14,25.Therefore, the increase in the permeability ofblood brain barrier due to exposure to EMR mayincrease the influx of glucose to the brain. It iswell known that glucose represents the mainsource of glutamate, aspartate and glycine26,27.Accordingly, the significant increase in most ofthe amino acids in the midbrain and cerebellum

recorded after 1 hour of EMR exposure, in the

many), a luna 5 C18 reversed phase column (5m particle size, 15 cm 4.6 mm I.D.) from phe-nomenex, Torrance, CA, USA, a WellchromSpectrophotometer K-260b with flow cell(Knauer, Berlin, Germany) and a Chromatogra-phy workstation (Eurochrom 2000, Knauer,Berlin, Germany). The mobile phase consisted of30/70 (v/v), methanol/water containing 0.6%glacial acetic acid and 0.008% triethylamine. Themobile phase was degassed through an in-line fil-ter degasser supplied with 13 mm 0.45 M nylon66 membrane filter (Phenomenex, Torrance, CA,USA) and operating by a model 0211 oil-lessvacuum pump. The flow rate was 1 m1/min.

Statistical Analysis

All data are expressed as mean S.E.M. (n),where n refers to the number of animals. Statisti-cal comparisons between the means of animals ex-posed to EMR and those of control animals werecarried out by the independent t-test using SPSS(Statistical Package for Social Sciences, Inc.,Chicago, IL, USA) version 14 for each of theadult and young rats in each time interval sepa-rately. Significance was determined atp

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Adult

Young

Time

before

Aminoacid

deca

pitation

Control

Treated

%D

Control

Treated

%D

Glutamicacid

1hour

7.760.11(7)

8.230.14(6)*

+6.06

6.650.12(6)

6.180.21(6)

-7.07

1month

5.300.44(7)

4.920.18(7)

-7.17

7.910.36(6)

6.330.37(7)*

-19.97

2months

6.560.33(6)

6.450.29(7)

-1.68

4.550.27(6)

4.280.19(7)

-5.93

4months

7.680.63(6)

7.080.20(7)

-7.81

6.610.27(6)

6.150.21(6)

-6.96

Stoppin

gfor1month

5.580.18(5)

5.180.17(7)

-7.17

5.230.09(7)

5.140.13(7)

-1.72

Asparticacid

1hour

4.820.19(7)

5.430.18(7)*

+12.66

3.090.11(6)

2.690.13(6)*

-12.94

1month

2.210.26(7)

1.990.14(7)

-9.95

3.990.29(7)

3.080.27(6)*

-22.81

2months

3.460.39(6)

3.310.20(7)

-4.34

2.060.19(5)

1.530.11(6)*

-25.73

4months

3.450.41(5)

2.980.11(6)

-13.62

2.960.22(5)

2.440.11(6)

-17.57

Stoppin

gfor1month

2.090.09(5)

1.960.08(8)

-6.22

2.230.06(7)

2.180.10(7)

-2.24

Glutamine

1hour

2.920.10(8)

2.810.10(7)

-3.77

3.660.12(7)

3.560.15(7)

-2.73

1month

4.170.34(7)

3.770.06(7)

-9.59

4.760.18(6)

3.910.30(6)*

-17.86

2months

4.300.24(6)

3.590.15(5)*

-16.51

3.060.17(7)

3.150.08(7)

+2.94

4months

3.420.18(6)

2.990.05(7)*

-12.57

4.150.11(7)

3.550.09(6)*

-14.46

Stoppin

gfor1month

3.820.15(5)

3.280.16(7)*

-14.14

3.050.07(7)

2.740.03(7)*

-10.16

T

ableI.EffectofEMR(frequency900M

zmodulatedat217Hz,SAR1.165W/kg

,powerdensity0.02mW/cm2)onexcitatoryaminoacidneurotransmitterconcentrationsinthe

m

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V

aluesrepresentmeanSEMwiththenu

mberofanimalsbetweenparentheses.*S

ignificantatP-value