Effect of Repeated Exposure to Lambda-Cyhalothrin and Immobilization or Forced Swim Stress on Oxidative Stress in Rat Brain

The present study has been undertaken to investigate role of immobilization stress (IMS), a psychological stressor and forced swim stress (FSS), a physical stressor on the neurobehavioral toxicity of lambda-cyhalothrin (LCT), a new generation, type-II synthetic pyrethroid with extensive uses to control insects and ectoparasites. Rats subjected to IMS (placed in plastic restrainer for 6 hour/day) or FSS (one session of 15 min/day) for 28 days exhibited a significant increase in lipid peroxidation and protein carbonyl levels in frontal cortex, corpus striatum, hippocampus and hypothalamus as compared to controls. Further, decrease in the levels of reduced glutathione and activity of superoxide dismutase, catalase and glutathione peroxidase was also observed in these brain regions of rats subjected either IMS or FSS as compared to rats in the control groups. No significant change in any of the parameters was observed in any of the brain regions of rats treated with LCT (0.5 mg/kg body weight, p.o., 28 days) as compared to controls. Simultaneous exposure of rats to LCT and IMS or FSS resulted to cause marked increase in protein carbonyl levels and lipid peroxidation as compared to controls. Further, decrease in the activity of superoxide dismutase, catalase and glutathione peroxidase, enzymes involved in antioxidant defense in these brain regions was also observed in rats simultaneously exposed to IMS or FSS and LCT as compared to controls. The data of the present study exhibit that both psychological and physical stress enhances the neurotoxicity of lambda-cyhalothrin by enhancing oxidative stress in rat brain.