Assessment of chlorpyrifos toxicity on certain organs in rat, Rattus norvegicus

Chlorpyrifos, an organophosphate insecticide of phosphorothioate group was orally administered to male rats at the doses of 3, 6 and 9 mg kg(-1) d(-1) for 90 days. Animals exposed to high dose (9 mg kg(-1) d(-1)) showed signs of toxicity including piloerection, diarrhoea, nose and eye bleeding, reduced body weight and death of animals. Organ weight ratio of different vital organs did not show any change except increase in adrenal weight and decrease in the weight of testes in animals of high dose (9 mg kg(-1) d(-1)). A dose dependent inhibition of acetylcholinesterase (AChE) activity in RBC (22-60%) and brain (7-52%) was observed. Microscopic examination of different tissues of male rats showed minor histopathological changes in brain, liver testis, epididymis and adrenal. The activity of testicular enzymes SDH, G-6-PDH and testicular content of sialic acid and cholesterol were found increased in animals of high dose (9 mg kg(-1) d(-1)). There was decrease in RBC counts and levels of hemoglobin (Hb) and hematocrit (HCT) with increase in WBC counts. While, total protein was decreased significantly at all the dose levels in testes and epididymis, glucose level showed a significant decrease at high dose. A dose dependent increase was observed in the level of serum triglycerides. There was no change in sperm motility and sperm morphology at any dose level except a decrease in sperm counts (114.1 x 10(6) g(-1) in high dose for group against 158.9 x 10(6) g(-1) controls). It is suggested that chlorpyrifos at 9 mg/kg/d dose for 90 days has caused toxicological changes along with mild testicular and spermatotoxic effects in male rats.