Effect of Monocrotophos Technical on pubertal development, reproductive and thyroid axis in female juvenile Rats

The study was conducted to evaluate the effect of monocrotophos technical (MCT) on intact juvenile/peripubertal female rats. Female pups from postnatal day (PND) 21 to 42 were dosed by oral gavage with vehicle (RO water) and the positive control 1-Chloro-2-Nitrobenzene (CNB)-100, and MCT-Low dose-0.1, MCT-Mid dose-1.0, and MCT-High dose-2.0 mg/kg body weight/day. Shivering was observed post-dosing in all animals treated with MCT at 2.0 mg/kg body wt./day. Significant reduction in body weight and mean body weight at vaginal opening was observed in animals treated with MCT at 2.0 mg/kg body wt./day. Estrous cycle was monitored from VO to necropsy for all animals. Animals treated with vehicle control, CNB, MCT showed irregular cycling. A difference of +0.54, -0.46, and-1.00 was observed in low, mid and high dose, respectively from control group (PND 39.33). Clinical pathological parameters ALT, urea, and BUN exhibited significant increase in high dose group. Pathological evaluation revealed that MCT at 2.0 mg/kg led to a decrease in liver, wet uterus, and kidney weight and hepatocellular glycogen depletion. No effect on serum thyroid hormones, thyroid weight and histopathology was observed in MCT treated groups. Thus, the study exhibited that MCT did not alter pubertal development and it did not produce any thyroid toxicity up to 2.0 mg/kg body wt./day though it caused systemic toxicity.