Sensorimotor and Cognitive Changes Induced by Subchronic Co-Administration of Chlorpyrifos and Lead in Wistar Rats: Mitigating Effect of Vitamin C

Abstract

The environment has been invaded by many contaminants, most of which are deliberately released as a result of man’s activity. The effect of multiple contaminants poses new environmental and health challenges to man and animals. Pesticides including organophosphate (OP) and heavy metals including lead are released into the environment as a result of man’s activity. Lead (Pb) and OP are nerve poisons that have been shown to induce neurobehavioral toxicity in man and animals. Oxidative stress is a common mechanism implicated in OP and lead poisoning. The present study was aimed at evaluating the ameliorative effect of antioxidant vitamin C on sensorimotor and cognitive changes induced by co-administration of chlorpyrifos (CPF), an OP insecticide and lead in Wistar rats. Forty adult male Wistar rats divided into 4 groups of 10 animals each were used for the study. Groups I, II, III were given soya oil (2 mg/kg b.wt.), vitamin C (100 mg/kg b.wt) and combination of CPF (4.25 mg/kg~1/20th LD ) and Pb (225 mg/kg~1/20th LD ), respectively. Group IV was 50 50 pretreated with vitamin C (100 mg/kg b.wt) and then co-administered with CPF (4.25 mg/kg b.wt) and Pb (225 mg/kg b.wt), 30 min later. The regimens were administered by gavage once daily for a period of 9 weeks. The animals were evaluated at various intervals during this period for neurobehavioral signs measuring neuromuscular and motor coordination, motor strength, learning and short-term memory. The animals were sacrificed and the brains evaluated for malonaldehyde (MDA) concentration. The result showed that impairments of neuromuscular and motor coordination, motor strength, learning and memory and an increase in brain MDA concentration induced by co-administration of CPF and Pb were mitigated by vitamin C. The study concludes that vitamin C mitigation of sensorimotor and cognitive deficits induced by coadministration of CPF and Pb was partly due to its anti-lipoperoxidative property.