ВЛИЯНИЕ МЕЛАТОНИНА НА ОБМЕН ГАМК В СТРУКТУРАХ ГОЛОВНОГО МОЗГА КРЫС В РАННЕМ ПОСТНАТАЛЬНОМ ОНТОГЕНЕЗЕ В УСЛОВИЯХ ТОЛУОЛЬНОЙ ИНТОКСИКАЦИИ

ВЛИЯНИЕ МЕЛАТОНИНА НА ОБМЕН ГАМК В СТРУКТУРАХ ГОЛОВНОГО МОЗГА КРЫС В РАННЕМ ПОСТНАТАЛЬНОМ ОНТОГЕНЕЗЕ В УСЛОВИЯХ ТОЛУОЛЬНОЙ ИНТОКСИКАЦИИ

Научная статья

Агаева С.В. *

Азербайджанский Государственный Педагогический Университет, Баку, Азербайджан

* Корреспондирующий автор (agaeva.samira.84[at]mail.ru)

Аннотация

Изучено влияние мелатонина на обмен ГАМК в различных тканях головного мозга месячных крыс в условиях интоксикации толуолом. Результаты наших исследований показали, что при воздействии толуола происходит увеличение содержания ГАМК, уменьшение содержания свободных Глу и Асп в различных структурах головного мозга месячных крыс. При этом активность ГДК повышается, активность ГАМК-Т понижается. После влияние мелатонина происходит частичное восстановление компонентов ГАМК при интоксикации толуолом. Мелатонин в головном мозге корректирует обмен ГАМК в условиях интоксикации толуолом.

Ключевые слова: мелатонин, толуол, гамма-аминомасляная кислота, глутаминовая кислота, аспарагиновая кислота, глутаматдекарбоксилаза, ГАМК-аминотрансфераза.

THE EFFECT OF MELATONİN ON GABA EXCHANGE IN THE BRAIN STRUCTURES OF RATS İN EARLY POSTNATAL ONTOGENESIS UNDER THE CONDITIONS OF TOLUENE INTOXICATION

Research article

Agayeva S.V. *

Azerbaijan State Pedagogical University, Baku, Azerbaijan

* Corresponding author (agaeva.samira.84[at]mail.ru)

Abstract

The study investigated the effect of melatonin on GABA exchange in different tissues of the brain of 1-month-old rats under the conditions of toluene intoxication. As a result of the toluene effect, the content of GABA has increased and the content of Glu and Asp has decreased in different brain structures of 1-month-old rats. At the same time, the activity of the GAD has increased, and the activity of the GABA-T has decreased. The effect of melatonin under the conditions of toluene intoxication has led to a partial recovery of all the components involved in the GABA exchange. Melatonin corrects GABA exchange in brain in the context of toluene intoxication.

Keywords: melatonin, toluene, gamma-aminobutyric acid, glutamic acid, aspartic acid, glutamate decarboxylase, GABA-aminotransferase.

Toluene is a neurotoxin substance. Its chronic use causes functional and structural disorders of various organs. Toluene alters the lipid structure of the cell wall and interacts with proteins because of their lipophilic nature [1], [2]. The primary effect of exposure to toluene in people and animals is CNS depression. Abuse of toluene has been shown to cause persistent changes in neuronal dysfunction in brain structures. In animals exposure to toluene causes reduction in the proliferation of neurons in the hippocampus [3], loss of pyramid neurons [4], gliosis [5], and changes in the expression of NMDA receptor subtypes [6]. Neurohormone, neuromediator changes and changes in the functions of their receptors have been observed as a result of the effect of this ecotoxicant [7], [8].

There is an evidence that neurotoxicity of toluene is minimized by melatonin, which is a strong antioxidant and neurohormone derived from tryptophan amino acid [9].

 Preparation of the necessary measures for correction of pathological processes and disorders in CNS during the influence of neurotoxicants is of great importance in theoretical and clinical medicine. To this end, it is of great interest to determine whether melatonin has the ability to correct changes in the metabolism of gamma-aminobutyric acid (GABA) in the brain in the context of toluene intoxication.

Methods

All experiments were conducted in accordance with the principles of the International Declaration of the European Union for the protection of animals used for experimental and other scientific purposes.

The experiments were conducted on 1 month-old white rats from Wistar line kept in vivarium under normal feeding conditions. The number of 1-month-old white rats used in the experiments was 60. The model of toluene intoxication was created by intraperitoneally (i.p.) injecting at a dose of 1000 mg/kg of toluene in animals [10].

Experimental animals were divided into the following groups: 1) control group (n=20); 2) experimental group. Experimental group animals were also divided into 2 subgroups: I subgroup - animals (n=20) exposed to toluene i.p. injection at 1000 mg/kg dose for 5 days, II subgroup - animals (n = 20) exposed to daily i.p. injection of melatonin at the dose of 10 mg/kg in toluene intoxication model (3 hours after toluene was i.p. injected at the dose of 1000 mg/kg for 5 days).

After the animals were decapitated, the brain was removed immediately and placed on ice. To brain was separated into the following structures - cortex of cerebral hemispheres, cerebellum, brain stem and hypothalamus according to the atlas of V.M.Svetukhina [11]. After brain tissue processing, [12], [13] separation of amino acids (GABA, Glu, Asp) was carried out on a paper via electrophoresis method at pH3,5 in buffer mixture containing water-icy acetic acid-pyridine (44:8:1) [14]. The amino acids were separated for 4 hours at 350 V voltage and 12.5 mA.

To determine the activity of glutamatedecarboxylase (GAD), I.A.Sytsinski, T.N.Priyatkina [15] method was used and determined based on the change in the amount of GABA (mkmol GABA/g.hour). The activity of GABA-aminotransferase (GABA-T) was determined by the method of Nilova N.S. [16] and based on the change of Glu amount (mkmol Glu/g.hour). The results obtained were processed according to Fischer, Student by Wilcoxon non-parametric (Manna-Whitney) statistical method.

Results and discussion

The results of the experiments showed that the content of GABA in the tissues of different brain structures of 1-month-old rats was 2.48±0.08 in the cortex of cerebral hemispheres, 2.15±0.07 in cerebellum, 1.81±0.05 in the brain stem, 2.91±0.11mkmol/g in hypothalamus (table 1). Even after the administration of toluene (i.p.) at a dose of 1000 mg/kg for 5 days of 1-month-old rats, the content of GABA in all tissues of structures was 41-71% higher than control. Melatonin was administered at the dose of 10 mg/kg 3 hours after injection of toluene at the dose of 1000 mg/kg daily for 5 days in 1-month old rats. In this case, the content of GABA increased by 13% in the tissues of the cortex of cerebral hemispheres, by 25% in the cerebellum, by 18% in the brain stem and by 15% in the hypothalamus in comparison with control.

 

Table 1 – Effect of melatonin on the content of GABA, Glu and Asp in different structures of the brain in early postnatal ontogenesis in the context of toluene intoxication (M±m, n=5)

Brain structures	Groups	GABA	Glu	Asp
Cortex of cerebral hemispheres	Control	2,48±0,08	4,42±0,13	2,93±0,10
	Toluene	3,87±0,11***	2,96±0,09***	1,85±0,07***
		156	67	63
	Toluene+ melatonin	2,80±0,07*	3,93±0,09*	2,55±0,09*
		113	89	87
Cerebellum	Control	2,15±0,07	4,73±0,16	2,77±0,11
	Toluene	3,68±0,15***	2,84±0,07***	1,63±0,08***
		171	60	59
	Toluene+ melatonin	2,69±0,09**	3,83±0,13**	2,16±0,08**
		125	81	78
Brain stem	Control	1,81±0,05	4,90±0,11	2,41±0,09
	Toluene	2,79±0,11***	3,19±0,16***	1,54±0,06***
		154	65	64
	Toluene+ melatonin	2,14±0,06**	4,17±0,17**	2,00±0,07**
		118	85	83
Hypothalamus	Control	2,91±0,11	5,45±0,17	3,35±0,13
	Toluene	4,10±0,14***	4,03±0,18***	2,41±0,10**
		141	74	72
	Toluene+ melatonin	3,35±0,10*	4,91±0,15*	3,05±0,09
		115	90	91

Note: * - p<0,05; ** - p<0,01; *** - p<0,001  

In 1-month-old control rats, the amount of Glu was 4.42±0.13 in the tissue of the cortex of cerebral hemispheres, 4.73±0.16 in the cerebellum, 4.90±0.11 in the brain stem, 5.45±0.17 mkmol/g in the hypothalamus. In the context of toluene intoxication, the amount of Glu decreased by 26-40% compared to control. As a result of melatonin injection (i.p.) under the condition of toluene intoxication, the amount of this amino acid was reduced by 11% in the tissue of the cortex of cerebral hemispheres, by 19% in cerebellum, 15% in the brain stem and by 10% in the hypothalamus in comparison with control.

In 1-month-old control rats, Asp content was 2.93±0.10 in the tissue of the cortex of cerebral hemispheres, 2.77±0.11 in the cerebellum, 2.41±0.09 in the brain stem, and 3.35±0.13 mkmol/g in the hypothalamus. There has been a 28-41% decrease in Asp level under the condition of toluene intoxication. The administration of melatonin (i.p.) under the condition of toluene intoxication has led to a decrease in the incidence of Asp level under the condition of toluene intoxication. Under appropriate conditions, the amount of Asp decreased by 13% in the tissue of the cortex of cerebral hemispheres, by 22% in the cerebellum, by 17% in the brain stem and by 9% in the hypothalamus, compared with control.

The activity of GAD enzyme in 1-month-old control rats was 62.46±3.87 in the tissue of the cortex of cerebral hemispheres, 75.05±3.69 in the cerebellum, 48.16±2.18 in the brain stem and 86.34±4.56 mkmol GABA/g.hour in the hypothalamus (table 2). In the context of toluene intoxication, the activity of the GAD enzyme increased by 48-78% compared to the control. As a result of melatonin administration (i.p.) under the condition of toluene intoxication, the amount of this amino acid increased by 17% in the tissue of the cortex of cerebral hemispheres, by 27% in the cerebellum, by 21% in the brain stem and by 14% in the hypothalamus, compared with control.

In 1-month-old control rats, the activity of the GABA-T enzyme was 60.27±2.79 in the tissue of the cortex of cerebral hemispheres, 69.63±3.52 in the cerebellum, 55.81±1.93 in the brain stem, and 76,08±3,37 mkmol Glu/g.hour in the hypothalamus. In the context of toluene intoxication, the amount of GABA-T decreased by 29-47% compared to control. As a result of melatonin injection (i.p.) under the condition of toluene intoxication, the amount of this amino acid was reduced by 13% in the tissue of the cortex of cerebral hemispheres, by 17% in the cerebellum, by 14% in the brain stem and by 19% in the hypothalamus.

Table 2 – Effect of melatonin on the activity of GAD and GABA-T different structures of the brain in early postnatal ontogenesis in the context of toluene intoxication

Brain structures	Groups	GAD (mkmol GABA/g.hour)	GABA-T (mkmol Glu/g.hour)
Cortex of cerebral hemispheres	Control	62,46±3,87	60,27±2,79
	Toluene	94,35±4,37***	40,95±1,64***
		151	68
	Toluene+ melatonin	73,05±2,18*	52,41±1,76*
		117	87
Cerebellum	Control	75,05±3,69	69,63±3,52
	Toluene	133,61±4,92***	36,94±1,50***
		178	53
	Toluene+ melatonin	95,30±2,84**	57,78±1,69*
		127	83
Brain stem	Control	48,16±2,18	55,81±1,93
	Toluene	77,53±3,60***	32,95±1,67***
		161	59
	Toluene+ melatonin	58,28±1,67**	49,13±1,38*
		121	86
Hypothalamus	Control	86,34±4,56	76,08±3,37
	Toluene	127,76±5,62***	54,09±1,93***
		148	71
	Toluene+ melatonin	98,43±2,27*	68,47±1,97
		114	90

Note: * - p<0,05; ** - p<0,01; *** - p<0,001  

Toluene has a regional specific effect on the transmission of GABA to the central nervous system [17]. Increase of the activity of GAD enzyme involved in the synthesis of GABA in the tissues of different brain structures in the context of toluene intoxication compared to control, and decrease in the activity of the GABA-T enzyme involved in the breakdown of this amino acid, explains the increase in GABA content. The effects of toluene on the presynaptic transmission of GABA depend from the brain structures. Toluene has a more direct effect on cerebellar GABAergic neurons. A high concentration of GABA in mammalian brain tissue indicates that its role in nervous activity is not limited to mediator function only. GABA indicates a high plasticity of the exchange in the central nervous system.

Toluene, which is lipophilic, rapidly dissolves in tissues and organs, damages the biological membrane and affects the stability of proteins, lipids and chromatin. Studies [18] showed that the effect of toluene causes increase of induction of the active form of oxygen (AFO) and oxidative stress. Melatonin regulates antioxidant enzymes [19], [20].

In addition, Mattia et al. [18] showed that i.p. injection of toluene causes a significant increase in the rate of formation of oxygen-active forms (OAF) and reduction of glutathione (GSH) level in brain. OAF in turn damages lipids, proteins and nucleic acids. It causes neurodegenerative disorders that mediate behavioral changes. The acute and chronic effects of toluene on neurons have been well documented [18].

As a powerful cleanser from free radicals [21] melatonin reduces oxidative-induced neurotoxicity [22]. It has been shown that melatonin modulates specific plasticity patterns in hippocampal pyramid neurons [23]. Melatonin injection may provide neuroprotection against toluene neurotoxicity by directly cleaning off AFO and indirectly increasing antioxidant strength [9].

Brains of animals exposed to toluene vapor and treated with melatonin reduce their free radical production, oxidation of lipids, and gliosis [9]. In addition, poor neocortical dendrition has been shown to be restored by melatonin injection in animals exposed to toluene [24]. Melatonin provided the best neuroprotective properties in neocortical pyramid neurons [24].

The ability of melatonin to reduce the neurotoxicity of various substances has been documented and it has been shown that the neuroprotective effects of melatonin are associated with its free radical clearance [25, 26]. Influence melatonin increased GABA in brain [27]. GABA can protect the brain against oxidative stress [28].

Conclusion

The results of our experiments showed that toluene intoxication resulted in an increase in the amount of GABA, a decrease in Glu levels, an increase in the activity of the GAD enzyme, and a decrease in the level of the GABA-T enzyme in the brain structures in comparison with control. It can be assumed that an increase in the amount of GABA in nerve cells is a compensatory reaction of the body during toluene intoxication. Changes in these levels were partially restored after melatonin administration in the context of toluene intoxication. Based on our findings, we can say that melatonin can prevent changes in the metabolism of toxicity in the context of toluene intoxication.

Конфликт интересов Не указан.

Conflict of Interest None declared.

 

Список литературы / References

1. Calderon-Cuzman D. Effect of toluene and nutritional status on serotonin, lipid peroxidation levels and NA+/K+-ATPase in adult rat brain / Calderon-Cuzman D., I. Espitia-Vazquez, A. Lopez-Domınguez et al. // Neurochemical Research, - 2005. - Vol.30. - №5. - P. 619-624.
2. Cruz S.L. Review of toluene action: clinical evidence, animal studies and molecular targets / S. L. Cruz, M. T. Rivera-Garcia, J. J. Woodward // Drug. Alcohol Res. – 2014. - 3: 235840. doi: 10.4303/jdar/235840.
3. Seo H.S. Toluene inhibits hippocampal neurogenesis in adult mice/ S. Seo, M. Yang, M. S. Song et al. // Pharmacol. Biochem. Behav. – 2010 – Vol. 94. – P. 588–594.
4. Korbo L. Neuronal loss in hippocampus in rats exposed to toluene / L. Korbo, O. Ladefoged, H. R. Lam et al. // Neurotoxicology. - 1996. – Vol. 17. - P. 359-366.
5. Gotohda T. Effect of toluene inhalation on astrocytes and neurotrophic factor in rat brain / T. Gotohda, I. Tokunaga, S. Kubo et al. // Forensic science international. – 2000. Vol. – 113. - 233- 238.
6. Bale A.S. Alterations in glutamatergic and gabaergic ion channel activity in hippocampal neurons following exposure to the abused inhalant toluene / A. S. Bale, Y. Tu, E.P. Carpenter-Hyland et al. // Neuroscience – 2005. - Vol. 130 – P. 197–206.
7. Perrine S.A. Binge toluene exposure alters glutamate, glutamine and GABA in the adolescent rat brain as measured by proton magnetic resonance spectroscopy / Perrine S.A., O'Leary-Moore S.K., Galloway M.P. et al. // Drug and alcohol dependence. – 2011. - Vol. 115. - №1-2. - P.101-106.
8. Shonagh K. O'L. Neurochemical Changes after Acute Binge Toluene Inhalation in Adolescent and Adult Rats: A High-Resolution Magnetic Resonance Spectroscopy Study / O'L Shonagh, P. G. Matthew, P. Mc. Andrew et al // Neurotoxicol Teratol. – 2009. – Vol. 31. - № 6. - P. 382-389.
9. Baydas G. Melatonin protects the central nervous system of rats against toluene-containing thinner intoxication by reducing reactive gliosis / G. Baydas, R. J. Wieraszko, V. S. Nedzvetskii et al // Lett. - 2003. – Vol. 137. – P. 169-174.
10. Dyer R.S. Acute exposures to p-xylene and toluene alter visual information processing / R. S. Dyer, M. S. Bercegeay, L. M. Mayo // Neurotox. Teratol. – 1988. – Vol. 10. – P. 147-153.
11. Светухина В.М. Цитоархитектоника новой коры мозга в отряде грызунов // Архив анатомии, эмбриологии и  гистологии. - 1962. - Т. 42. - № 2. - С. 31–45.
12. Robert E. Gamma-aminobutyric acid in brain: its formation from glutamic acid / E. Robert, S. Frankel // J.Biol. Chem. – 1950. – 187. - №1. - P. 55-63.
13. Shatunova N. F. On the intracellular localization of glutamate decarboxylase and gamma-amonibutyric acid in mammalian brain / N. F. Shatunova, I. A. Sytinsky // J. Neurochem. - 1964. – Vol. 11. - P. 701-708
14. Doze K. Dir anvendug der hochspanmumgspherographie dei der guantitativen totalanoiyse von protein hydrolysaten / K. Doze // Mittelling Biochem. Z. - 1957. - Vol. 329. - № 2. - P. 390-398.
15. Sytinsky I. A. Effect of certain drugs on gamma-aminobutyric acid system on central nervous system / I. A. Sytinsky, T. N. Priyatkina // Biochem. Pharmacol. - 1966. - Vol. 115. - № 1 - P. 49-57.
16. Нилова Н. С. Аммиак и ГАМК-трансаминазная активность ткани головного мозга / Н. С. Нилова // Докл. АН СССР. – 1966. - Т. 2. - С. 483-486.
17. Stengard K. Acute toluene exposure increases extracellular GABA in the cerebellum of rat: a microdialysis study / K. Stengard, R. Tham, W. T. O'Connor et al // Pharmacology & Toxicology – 1993 – Vol. 73 – P. 315-318.
18. Mattia C.J. Toluene-induced oxidative stress in several brain regions and other organs / C. J. Mattia, S. F. Ali, S. C. Bondy // Mol Chem Neuropathol. – 1993. – Vol. 3. – P. 313-328.
19. Reiter R.J. Melatonin reduces oxidative/nitrosative stress due to drugs, toxins, metals and herbicides / R. J. Reiter, A. Korkmaz, S. D. Paredes et al // Lett. - 2008. – Vol. 29. – P. 101-105.
20. Reiter R.J. Melatonin combats molecular terrorism at the mitochondrial level / R. J. Reiter, S. D. Paredes, A. Korkmaz et al // Toxicol. - 2008. – Vol. 1. - P. 137-149.
21. Allegra M. The chemistry of melatonin’s interaction with reactive species / M. Allegra, R. J. Reiter, D. X. Tan et al // J. Pineal Res. – 2003. – Vol. 34. – P. 1-10.
22. Baydas G. Inhibitory effects of melatonin on neural lipid peroxidation induced by intracerebroventricularly administered homocysteine / G. Baydas, S. Kutlu, M. Naziroglu et al // J. Pineal Res. – 2003. – Vol. 34. P. 36-39.
23. EL-Sherif Melatonin regulates neuronal plasticity in the hippocampus / Y. EL-Sherif, J. Tesoriero, M. V. Hogan, A. Wieraszko // J. Neurosci Res. – 2003. – Vol. 72. - P. 454-460.
24. Pascual R. Melatonin ameliorates neocortical neuronal dendritic impairment induced by toluene inhalation in the rat / R. Pascual, S. Zamora-Leon, N. Perez et al // Exp. Toxicol. Pathol. - 2010 - doi: 10.1016/j.etp 201003.006.
25. Stankov B. Melatonin signal transduction and mechanism of action in the central nervous system: using the rabbit cortex as a model / B. Stankov, G. Biella, C. Panara et al // Endocrinology - 1992. – Vol. 130. – P. 2152– 2159
26. Alghamdi B. S. The neuroprotective role of melatonin in neurological disorders / B. S. Alghamdi // Neuro. Res. – 2018. - Vol. 96. - P. 1136-1149.
27. Niles L.P.  Melatonin Interaction with BZ-GABA_AReceptors /P. Niles // Sleep and Sleep Disorders. – 2006. - P. 95-99.
28. Eltahawy N. A. Gamma Amino Butyric Acid Attenuates Brain Oxidative Damage Associated with Insulin Alteration in Streptozotocin-Treated Rats / N. A. Eltahawy, H. N. Saada, A. S. Hammad // Ind J. Clin. Biochem. – 2017. – Vol. 32. - № 2. – P. 207-213.

Список литературы на английском языке / References in English

1. Calderon-Cuzman D. Effect of toluene and nutritional status on serotonin, lipid peroxidation levels and NA+/K+-ATPase in adult rat brain / Calderon-Cuzman D., I. Espitia-Vazquez, A. Lopez-Domınguez et al. // Neurochemical Research, - 2005. - Vol. 30. - № 5. - P. 619-624.
2. Cruz S.L. Review of toluene action: clinical evidence, animal studies and molecular targets / S. L. Cruz, M. T. Rivera-Garcia, J. J. Woodward // Drug. Alcohol Res. – 2014. - 3: 235840. doi: 10.4303/jdar/235840.
3. Seo H.S. Toluene inhibits hippocampal neurogenesis in adult mice/ S. Seo, M. Yang, M. S. Song et al // Pharmacol. Biochem. Behav. – 2010 – Vol. 94. – P. 588–594.
4. Korbo L. Neuronal loss in hippocampus in rats exposed to toluene / L. Korbo, O. Ladefoged, H. R. Lam et al // Neurotoxicology. - 1996. – Vol. 17. - P. 359-366.
5. Gotohda T. Effect of toluene inhalation on astrocytes and neurotrophic factor in rat brain / T. Gotohda, I. Tokunaga, S. Kubo et al // Forensic science international. – 2000. Vol. 113. - P. 233- 238.
6. Bale A.S. Alterations in glutamatergic and gabaergic ion channel activity in hippocampal neurons following exposure to the abused inhalant toluene / A. S. Bale, Y. Tu, E.P. Carpenter-Hyland et al // Neuroscience – 2005. - Vol. 130 – P. 197–206.
7. Perrine S.A. Binge toluene exposure alters glutamate, glutamine and GABA in the adolescent rat brain as measured by proton magnetic resonance spectroscopy / Perrine S.A., O'Leary-Moore S.K., Galloway M.P. et al. // Drug and alcohol dependence. – 2011. - Vol. 115. - №1-2. - P.101-106.
8. Shonagh K. O'L. Neurochemical Changes after Acute Binge Toluene Inhalation in Adolescent and Adult Rats: A High-Resolution Magnetic Resonance Spectroscopy Study / O'L Shonagh, P. G. Matthew, P. Mc. Andrew et al // Neurotoxicol Teratol. – 2009. – Vol. 31. - № 6. - P. 382-389.
9. Baydas G. Melatonin protects the central nervous system of rats against toluene-containing thinner intoxication by reducing reactive gliosis / G. Baydas, R. J. Wieraszko, V. S. Nedzvetskii et al // Lett. - 2003. – Vol. 137. – P. 169-174.
10. Dyer R.S. Acute exposures to p-xylene and toluene alter visual information processing / R. S. Dyer, M. S. Bercegeay, L. M. Mayo // Neurotox. Teratol. – 1988. – Vol. 10. – P. 147-153.
11. Svetukhina V.M. Tsitoarkhitektonika novoy kory mozga v otryade gryzunov [Cytoarchitectonics of the Neocortex in Rodents]. Arkhiv anatomii, embriologii i gistologii, 1962, vol. 42, no. 2, pp. 31–45. [in Russian]
12. Robert E. Gamma-aminobutyric acid in brain: its formation from glutamic acid / E. Robert, S. Frankel // J.Biol. Chem. – 1950. – Vol. 187. - №1. - P. 55-63.
13. Shatunova N. F. On the intracellular localization of glutamate decarboxylase and gamma-amonibutyric acid in mammalian brain / N. F. Shatunova, I. A. Sytinsky // J. Neurochem. - 1964. – Vol. 11. - P. 701-708
14. Doze K. Dir anvendug der hochspanmumgspherographie dei der guantitativen totalanoiyse von protein hydrolysaten / K. Doze // Mittelling Biochem. Z. - 1957. - Vol. 329. - № 2. - P. 390-398.
15. Sytinsky I. A. Effect of certain drugs on gamma-aminobutyric acid system on central nervous system / I. A. Sytinsky, T. N. Priyatkina // Biochem. Pharmacol. - 1966. - Vol. 115. - № 1 - P. 49-57.
16. Nilova N. S. Ammiak i GAMK-transaminaznaja aktivnost' tkani golovnogo mozga [Ammonia and GABA transaminase activity of brain tissue] / N. S. Nilova // Reports of the Academy of Sciences of the USSR. – 1966. – V. 2. – P. 483-486. [in Russian].
17. Stengard K. Acute toluene exposure increases extracellular GABA in the cerebellum of rat: a microdialysis study / K. Stengard, R. Tham, W. T. O'Connor et al // Pharmacology & Toxicology – 1993. – Vol. 73 – P. 315-318.
18. Mattia C.J. Toluene-induced oxidative stress in several brain regions and other organs / C. J. Mattia, S. F. Ali, S. C. Bondy // Mol Chem Neuropathol. – 1993. – Vol. 3. – P. 313-328.
19. Reiter R.J. Melatonin reduces oxidative/nitrosative stress due to drugs, toxins, metals and herbicides / R. J. Reiter, A. Korkmaz, S. D. Paredes et al. // Lett. - 2008. – Vol. 29. – P. 101-105.
20. Reiter R.J. Melatonin combats molecular terrorism at the mitochondrial level / R. J. Reiter, S. D. Paredes, A. Korkmaz et al // Toxicol. - 2008. – Vol. 1. - P. 137-149.
21. Allegra M. The chemistry of melatonin’s interaction with reactive species / M. Allegra, R. J. Reiter, D. X. Tan et al // J. Pineal Res. – 2003. – Vol. 34. – P. 1-10.
22. Baydas G. Inhibitory effects of melatonin on neural lipid peroxidation induced by intracerebroventricularly administered homocysteine / G. Baydas, S. Kutlu, M. Naziroglu et al // J. Pineal Res. – 2003. – Vol. 34. P. 36-39.
23. EL-Sherif Melatonin regulates neuronal plasticity in the hippocampus / Y. EL-Sherif, J. Tesoriero, M. V. Hogan, A. Wieraszko // J. Neurosci Res. – 2003. – Vol. 72. - P. 454-460.
24. Pascual R. Melatonin ameliorates neocortical neuronal dendritic impairment induced by toluene inhalation in the rat / R. Pascual, S. Zamora-Leon, N. Perez et al // Exp. Toxicol. Pathol. - 2010 - doi: 10.1016/j.etp 201003.006.
25. Stankov B. Melatonin signal transduction and mechanism of action in the central nervous system: using the rabbit cortex as a model / B. Stankov, G. Biella, C. Panara et al.  // Endocrinology - 1992. – Vol. 130. – P. 2152– 2159
26. Alghamdi B. S. The neuroprotective role of melatonin in neurological disorders / B. S. Alghamdi // Neuro. Res. – 2018. - Vol. 96. - P. 1136-1149.
27. Niles L.P.  Melatonin Interaction with BZ-GABA_AReceptors /P. Niles // Sleep and Sleep Disorders. – 2006. - P. 95-99.
28. Eltahawy N. A. Gamma Amino Butyric Acid Attenuates Brain Oxidative Damage Associated with Insulin Alteration in Streptozotocin-Treated Rats / N. A. Eltahawy, H. N. Saada, A. S. Hammad // Ind J. Clin. Biochem. – 2017. – Vol. 32. - № 2. – P. 207-213.