Endosulfan and Its Toxicity on GABA, 5-HT, and Dopamine in the Albino Rat Brain
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DOI: 10.14744/ejmi.2018.47965 EJMI 2018;2(2):76–79 Research Article Endosulfan and its toxicity on GABA, 5-HT, and Dopamine in the Albino Rat Brain Jyoti Batra,1 Sudeep Kumar,1 P.k Seth2 1Department of Biochemistry, Santosh Medical College, Ghaziabad, India 2Department of Toxicology Division Industrial Toxicology Research Centre Lucknow, U.P, India Abstract Objectives: The objective of this study was to investigate the effects of endosulfan administration on gamma-amino- butyric acid (GABA), 5-HT, and dopamine. Methods: Ex vivo magnetic resonance spectroscopy along with high performance liquid chromatography was used to analyze forebrain tissue from rats that were administered oral endosulfan for 4 hours, 18 hours, and 18 days. Results: In the endosulfan-treated rats, a significant dose-dependent increase in the binding of [3H]-5 HT in the fron- tal cortex was seen after 18 hours in the endosulfan-treated rat. However, no such effect was observed after 4 hours of treatment and no significant changes were detected in GABA receptor binding following exposure to endosulfan. Monoamine oxidase activity was significantly decreased in the corpus striatum of the animals exposed to endosulfan at a dose of 5 mg and 15 mg/kg body weight for 18 days. Conclusion: The maximum number of binding sites for dopamine and an increase in serotonin receptor sites without any change in the binding affinity was observed after administration of endosulfan in albino rats. Keywords: Dopamine, endosulfan, gamma-amino-butyric acid, 5-HT ndosulfan and hexachlorocyclohexane both belonging gredient is mixture of two isomers α and β, in the ratio of Eto the chlorinated group of pesticides, are widely used approximately 70% and 30% respectively.[2] Endosulfan has for crop protection. Endosulfan has been reported to cause been reported to cause central nervous system disorders in central nervous system disorders in industrial workers and industrial workers and farmers. The individual and farmers farmers. The individual and farmers exposed to high levels exposed to high levels of Endosulfan are reported to exhib- of Endosulfan are reported to exhibit epilepsy, hyperactiv- it epilepsy, hyperactivity irritability, tremors, convulsions ity irritability, tremors, convulsions and paralysis. Experi- and paralysis. Experimental studies show that Endosulfan mental studies show that Endosulfan affects the levels of affects the levels of some neurotransmitters and their re- some neurotransmitters and their receptors.[1] ceptors.[3] Endosulfan is a broad-spectrum organochlorine insecticide Major neurotransmitter receptors including acetylcho- and acaricide for control of agriculture pests on a variety line (muscarinic), dopamine, serotonin (5HT) and GABA of field, fruit, and vegetable crops. Endosulfan active in- are known to transducer their signals to the cell interiors Address for correspondence: Jyoti Batra, MD. Biyokimya Bolumu, Santosh Tip Fakultesi, Ghaziabad, India Phone: 09810062573 E-mail: [email protected] Submitted Date: February 09, 2018 Accepted Date: February 30, 2018 Available Online Date: May 17, 2018 ©Copyright 2018 by Eurasian Journal of Medicine and Investigation - Available online at www.ejmi.org EJMI 77 through the phosphoinositide derived messenger system. Table 1. Effect of Endosulfan on the activity of Monoamine Endosulfan residue has been identified in a variety of en- Oxidase (MAO) and Glutamate Dehydrogenase (GDH) vironmental media (air, surface water, ground water, soil Treatment Activity of Activity of Activity of and sediment) and its metabolites have been reported in striatal cortical Glutamate human and domestic animals milk [4, 5], fruit and vegetable. monoamine monoamine dehydrogenase [6, 7] The most likely way for people to be exposed to endo- oxidase oxidase sulfan is eating the contaminated food with it. Exposure to Control 1.64±0.12 2.0±0.40 16.8±0.6 endosulfan may occur by breathing, eating, or drinking the 5 mg/kg b.w 0.50±0.09*** 1.6±0.2 14.2±1.9 [8] substance, or by skin contact. In mammals, commercial 15 mg/kg b.w 0.69±0.12** 0.7±0.3* 15.1±0.8 endosulfan is transformed into more water soluble metab- Activity of GDH is expressed in U/mg of protein olites, mostly endosulfan sulfate, followed by ether and Activity of MAOis expressed in terms of n moles of benzaldehyde formed diol metabolites. All of these metabolites are bio accumu- min-1 mg-1 of protein. Data are mean±S.E from six animals lated in the adipose tissue, depending on their lipophilicity. *p<0.05, **p<0.01, ***p<0.001 [9] Hence, information on the mechanism of neurotoxicity of these pesticides is needed to develop suitable therapeutic Results measures against them. The binding of spiperone was found to be decrease in a dose Methods dependent manner on exposure to Endosulfan at a dose of 5 mg and 15 mg/kg body weight. The decrease in the binding All procedures were in accordance with the National Insti- of [3H]-spiperone was more pronounced, when the animals tute of Health’s Guide for the Care and Use of Laboratory were exposed to 15 mg/kg body weight Endosulfan, for 18 Animals, as well as the guidelines of the Animal Welfare Act. days. Methods A significant dose dependant increase in the binding of [3H]-5 Adult male wistar albino rats of industrial toxicology Re- HT was observed in the frontal cortex after 18 hours. Howev- search Centre, breeding colony, Lucknow were used in this er, no such effect of the Endosulfan seen after 4 hours treat- study. Adult male wistar albino rats were used. Chemical En- ment. Scatchard analysis [3H] spiperone binding revealed dosulfan obtained from Hoechest pharmeceuticals limited. that the decrease in the binding was due to the decrease in All the chemicals used were analar or guaranteed grade. the maximum number of binding sites (Bmax) without any Treatment of Animals: change in the affinity of the receptor. Similarly the increase in the 5-HT binding was due to increase in the maximum num- Endosulfan was dissolved in corn oil and administered oral- ber of 5-HT binding sites. ly with the help of cannula. Endosulfan (5mg and 15 mg/kg No significant changes in the GABA receptors binding follow- body weight) was administered for four hours and daily up ing exposure to Endosulfan were observed. to 18 hours. The control rats received corn oil (2mg/kg body weight) in an identical manner for both the groups. In vitro studies showed that Endosulfan at concentration of 10-4 M and 10-6 M decreased the binding of [3H] spiperone Biochemical Assays indicating a direct effect of Endosulfan on the rat dopamine Preparation of crude synaptic membrane and neurotrans- receptors levels; the decrease was significant at the 10-4 M mitter receptor binding assay. concentration of Endosulfan. When studied at the concentra- A crude membrane fraction was prepared from brain regions tions ranging from 10-4 M to 10-6 M of Endosulfan, no such by homogenisation of tissue in 19 volumes of 0.32 M sucrose change was observed in the binding of [3H]-5 HT. followed by centrifugation for 14 minutes.[10] Monoamine oxidase activity was significantly decreased in Determination of Glutamate Dehydrogenase Activity the corpus striatum of the animals exposed to Endosulfan The enzyme activity was measured by method of Rajlaxmi at a dose of 5 mg and 15 mg/kg body weight for 18 days. et al.[11] The lower dose was found to have no such effect on frontal monoamine oxidase activity (Table 1). Protein Estimation The protein was estimated by lowry method [12] Discussion Determination of Monoamine Oxidase Activity The present observations show that repeated administra- The enzyme activity was measured by the method of tabor tion of Endosulfan causes a marked alteration in the lev- et al.[13] els of dopamine and 5 HT receptors. The decrease in the 78 Batra. et al., Effect of Endosulfan on Rat Brain / doi: 10.14744/ejmi.2018.47965 dopamine receptor binding suggests disturbance in the cant decrease in the binding of 3H – Mucimol to cerebellar dopaminergic system, due to exposure of Endosulfan. Do- membrane at the doses of 1 and 5 mg/kg body weight in pamine system plays a significant role in the regulation of GABAergic neurotransmission in rat brain on haloperidol locomotor activity. The decrease in the number of binding treatment and suggest that other drugs of this group may sites of dopamine receptors in the brain was also observed also be involving GABAergic system in their action.[20] which may be indicative of increased dopamine levels, since sensitivity of dopamine receptor is often modified by Conclusion a change in the availability of neurotransmitter within the The present study showed that the decrease in the maxi- [14] synapse. mum number of binding sites of dopamine and increase The present study shows that exposure to Endosulfan leads in the serotonin receptors sites without any change in the to increase in the levels of serotonin receptors in the frontal binding affinity. The alterations in the binding of DA and cortex region of the brain. Our study suggests that the re- 5 HT receptors are suggestive of the disturbances in these ceptor binding of [3H]-5HT was increased further conferm- neurotransmitter systems. The study showed that the do- ing the previous observation, since the increase in binding pamine receptors are more sensitive to Endosulfan than may be due to decreased serotonin levels in the rat brain. other neurotransmitter receptors. Involvement of serotonergic system in the neurotoxicity induced by Endosulfan has been suggested by many in- Disclosures vestigators. We found the increase in [3H] –HT binding are Peer-review: Externally peer-reviewed. in-accordance with the previous observation.[15] Conflict of Interest: None declared. It is significant to note that in comparison to other neu- References rotransmitters, dopamine receptors appeared to be more sensitive to Endosulfan.