Hexachlorocyclohexane differentially alters the antioxidant status of the brain regions in rat

Hexachlorocyclohexane (HCH), a highly persistent organochlorine insecticide, is neurotoxic at acute doses and causes degenerative effects on chronic exposure. HCH has been reported to induce oxidative stress in cells and tissues. Mammalian brain is sensitive to oxidative stress which is implicated in neurodegenerative diseases. Effect of HCH on the brain regions, cortex, cerebellum, midbrain and brainstem, has been investigated by studying the response of antioxidant enzymes in rats treated orally with HCH at 25 and 100mg/kg b.w. for 2 weeks. Lipid peroxidation and glutathione depletion was seen in all the brain regions of HCH treated rats. The brain regions showed distinct variation in the antioxidant enzyme activities. Activities of glutathione peroxidase, glutathione reductase, glutathione-S-transferase and catalase were markedly induced whereas superoxide dismutase was inhibited at higher dose in all the brain regions. Marked induction and inhibition of the antioxidant enzymes, especially in the cortex and to varying degrees in other brain regions, was seen in HCH treated rats. These biochemical changes suggest vulnerability to oxidative stress in the brain is region-specific. Whether these changes are adaptive or compromise the capacity of the brain to deal with the HCH-induced oxidative stress that could lead to degenerative neurotoxic manifestations remain to be understood.