Protective role of melatonin on PCB (Aroclor 1,254) induced oxidative stress and changes in acetylcholine esterase and membrane bound ATPases in cerebellum, cerebral cortex and hippocampus of adult rat brain.

Polychlorinated biphenyls (PCBs) are one of the environmental toxicants and neurotoxic compounds which induce the production of free radicals leading to oxidative stress. Membrane proteins that control ion gradients across organellar and plasma membranes appear to be particularly susceptible to oxidation induced changes. Melatonin plays an important role in neurodegenerative diseases as an antioxidant and neuroprotector. The aim of this study was to determine the protective role of melatonin on PCB (Aroclor 1254) induced changes in activities of membrane bound ATPases and acetylcholine esterase in selected brain regions of adult rats. Group I: rats intraperitoneally (i.p.) administered corn oil (vehicle) for 30 days. Group II: rats injected i.p. with Aroclor 1,254 (PCB) at 2mg/kg bw/day for 30 days. Groups III and IV: rats intraperitoneally received melatonin (5 or 10mg/kg bw/day) simultaneously with Aroclor 1,254 for 30 days. Groups V and VI: rats intraperitoneally received melatonin (5 or 10mg/kg bw/day) alone for 30 days. After 30 days, rats were sacrificed and the brain regions were dissected to cerebral cortex (Cc), cerebellum (C) and hippocampus (H). Lipid peroxidation (LPO), hydrogen peroxide (H(2)O(2)), hydroxyl radical (OH) and the activities of Na(+)K(+) ATPase, Ca(2+) ATPase, Mg(2+) ATPase and acetyl cholinesterase were determined. Reduced glutathione (GSH) level was also determined. Melatonin levels in serum was measured by enzyme labeled immunosorbent assay (ELISA). Activities of all the enzymes and GSH level were decreased while an increase in H(2)O(2), OH and LPO were observed in brain regions of PCB treated animals. Melatonin levels in serum was decreased in PCB exposed animals. Exogenous melatonin supplementation retrieved all the parameters, significantly. These results suggest that PCB alters membrane bound ATPases and cholinergic function by inducing oxidative stress in brain regions, which can be protected by melatonin.