Polychlorinated Biphenyl (PCBs)-Induced Oxidative Stress Plays a Critical Role on Cerebellar Dopaminergic Receptor Expression: Ameliorative Role of Quercetin

Polychlorinated biphenyls (PCBs) exposure produces profound damage to the developing as well as adult central nervous system. Locomotor activities which are closely linked to dopaminergic neurotransmission are often impaired in PCBs toxicity. Targeting PCBs-induced oxidative stress using natural antioxidants is an attractive approach. Quercetin, a flavonoid is a safe and potent neuroprotective antioxidant. In this study, we sought to examine the protective role of quercetin against PCBs-induced neurodegeneration and dysfunction of dopaminergic receptors in the cerebellar region of adult male rats. They were divided into four groups. Group I received only vehicle (corn oil) intraperitoneally (i.p); Group II received Aroclor 1254 at a dose of 2 mg/kg bwt/day (i.p); Group III received Aroclor 1254 (i.p) and simultaneously quercetin (50 mg/kg bwt/day) through gavage; Group IV received quercetin alone (gavage). After 30 days treatment, rats were euthanized. The cerebellum was dissected from each rat brain, the levels of hydrogen peroxide, lipid peroxidation, protein carbonyl content, and activities of creatine kinase, acetylcholine esterase, membrane-bound ATPases were evaluated. Expressions of dopaminergic receptors and tyrosine hydroxylase in cerebellum were studied by semi-quantitative RT-PCR and western blot analysis, respectively. The PCBs-induced neurodegeneration was assessed by histological studies. Results proclaim that PCBs disturb dopaminergic receptors and also causes neurodegeneration in cerebellum via production of ROS. Simultaneous quercetin treatment had scavenged the free radicals induced by PCBs and protected dopaminergic receptors dysfunction in rat cerebellum.