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Arsenic Induced Perturbations in Cholinergic System and Energy Metabolism in Young and Adult Rat Brain: Reversal Effect of Vitamin-E

Abstract

Arsenic (As) occurs naturally as an element, ranks as the 20th most occurring trace element in the earth‟s crust. Arsenic is a known human carcinogen which acts via a genotoxic mechanism. Chronic exposure to inorganic arsenic compounds may lead to peripheral and central neurotoxicity. The aim of this study was to examine the impact of As exposure on cholinergic system and energy metabolism. In the present study the three months albino rats were exposed to low dose (1.5 mg/kg body weight) and high dose (3 mg/kg body weight) of As through intraperitonial injection daily for a period of 3 weeks. After the period of dosage, the As exposed animals were divided in to two groups of which one group of both the doses were given Vitamin – E at a dose for a period of one week. The specific activity of enzyme AChE and ACh content were estimated in synaptosomal fractions of cerebral cortex, hippocampus and cerebellum of control and all As exposed rats. The specific activity of enzymes Mg2+ ATPase and Na+K+ATPase were determined in the mitochondrial fraction of cerebral cortex, hippocampus and cerebellum of control and all As exposed rats. It was observed that AChE, Mg2+ ATPase and Na+K+ATPase activities were decreased and ACh content was increased in cerebral cortex, hippocampus and cerebellum of As-exposed (both low and high dose) rats when compared to control rats. The effect of As was highly pronounced in high dose As exposed animals compared to the low dose exposed rats. However, AChE, Mg2+ ATPase and Na+K+ATPase activities were increased and ACh content was decreased in the rats supplemented with Vitamin-E along with low dose and high dose of As. Among the three brain regions the cerebral cortex was found to be more susceptible region towards As induced toxicity compared to the, hippocampus and cerebellum. This study demonstrates exposure to As provoked neuronal injury by inducing alterations in enzymes of cholinergic system and energy metabolism in dose dependent manner, where high dose exposure showed significant alterations compared to the low dose exposure. However, Vitamin-E treatment have partial ameliorative effects on these disturbance caused by As toxicity.

C. Bhuvaneswari Devi, K. Kiran Kumari, G. Indravathi

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