Effect of chlorpyrifos on thiobarbituric acid reactive substances, scavenging enzymes and glutathione in rat tissues.

The present study showed that exposure of chlorpyrifos, O,O'-diethyl-O-3,5,6-trichloro-2-pyridyl phosphorothionate (CPF), a widely used pesticide in rats caused significant inhibition of acetylcholinesterase (AChE) activity in different tissues viz., liver, kidney and spleen. CPF exposure also generated oxidative stress in the body, as evidenced by increase in thiobarbituric acid reactive substances (TBARS), decrease in the levels of superoxide scavenging enzymes viz., superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in liver, kidney and spleen at all doses. Malondialdehyde levels were increased by 14%, 31% and 76% in liver, 11%, 31% and 64% in kidney and 32%, 75% and 99.9% in spleen when 50 mg, 100 mg and 200 mg/kg body wt. CPF was administered for three days. SOD and CAT activities were decreased in liver, kidney and spleen, while GPx activity showed slight increase in kidney at 50 mg and 100 mg dose, and decreased on further increase in dose of CPF. Liver and spleen showed dose-dependent decrease in GPx activity. The levels of reduced glutathione (GSH) was decreased, while oxidized glutathione (GSSG) was increased, thus a marked fall in GSH/GSSG ratio was observed in all tissues. A maximum decrease of 83% was observed in liver, followed by kidney and spleen, which showed 78% and 57% decrease, respectively in group given 200 mg/kg CPF. The levels of glucose-6-phosphate dehydrogenase (G6PDH) and glutathione reductase (GR) were also decreased in liver and kidney, while spleen showed increase at lower doses, but decrease at high dose of CPF. The data provide evidence for induction of oxidative stress on CPF exposure.