Effects of dermal exposure to chlorpyrifos on liver and brain structures and biochemical parameters in rabbits

Chlorpyrifos, an organophosphate insecticide, inhibits the enzyme acetylcholinesterse resulting in the accumulation of acetylcholine at the nerve endings. In the present research chlorpyrifos was administered via dermal contact to New Zealand white rabbits to determine its effects on biochemical indices on the rabbits as well as the pathological changes in their liver and brain. Twelve adult male rabbits were randomly assigned to two equal groups (N=6; treatment and control group). The treatment group received chlorpyrifos via dermal contact at the doses of 50 mg per kilogram body weight everyday during the first week. The daily doses for the second, third, and fourth weeks were 100, 250, and 400 mg/kg body weight, respectively. The control group received ethyl alcohol as the solvent of chlorpyrifos during the same period. Blood samples from marginal ear vein of both groups were collected on days 0, 7, 14, 21, and 28. Statistical study revealed that chlorpyrifos has harmful effects on the biochemical indices of the treated rabbits. These changes included significant increase in the level of ALP, AST, ALT, and cholesterol in the serum (p<0.05, p<0.01). Also significant decrease was observed in triglyceride and total protein level of the serum in the treatment group as compared with the control group (p<0.05). On day 28, the rabbits in both groups were euthanized. Histopathological changes including necrosis of hepatocytes, infiltration of lymphocyte cells, hyperemia, and proliferation of fibroblasts were observed in liver tissue of the exposed rabbits. In addition, necrosis of neuron, encephalitis (perivascular cuffing), hyperemia in blood vessels, gliosis, and necrosis of Purkinje cells in cerebellum were seen in the brain sections. The study confirmed that organophosphate intoxication from chlorpyrifos can occur via dermal exposure. Dermal contact to chlorpyrifos can have toxic effects on biochemical indices. It can also have pathologic effects on the liver and brain tissue.