Effect of endosulfan on ovarian compensatory hypertrophy in hemicastrated albino mice

Endosulfan, a chlorinated cyclodiene insecticide, was administered orally at 1.5, 3, 6, and 9 mg/kg per day to normal hemicastrated virgin mice for 15 consecutive days to examine the effect on ovarian function. Sham-operated and hemicastrated control mice were administered a similar volume of olive oil. The vaginal smear and body weight of the mice were recorded daily and mice were sacrificed on day 16. The remaining left ovary, uterus, kidney, adrenal, liver, thymus, and thyroid were removed and weighed. The left ovary from each animal was serially sectioned and stained for histologic studies. The hemicastrated control mice had a 40.5% increase in weight of the remaining left ovary and a significant increase in healthy and atretic follicles when compared with sham-operated controls. The remaining left ovaries of mice treated with 1.5 mg endosulfan had a 37.2% increase in weight with no significant difference in ovarian weight and or in the healthy and atretic follicles when compared with hemicastrated olive oil-treated controls. However, treatment with 3, 6, and 9 mg endosulfan resulted in weight increases in the remaining left ovary of only 14.9, 7.4, and 0.8% and a significant decrease in healthy follicles with a concomitant increase in the number of atretic follicles compared to the olive oil-treated controls. There was no significant change in the number of estrous cycles or the duration of each phase of the estrous cycle with 1.5 and 3 mg/kg per day endosulfan. However, there was a significant decrease in the number of estrous cycles, and the duration of estrus and metestrus with a concomitant significant increase in the duration of the diestrus phase with 6 and 9 mg/kg per day endosulfan treatment when compared with hemicastrated olive oil-treated controls. There were no significant change in body weight or the weights of the uterus, kidney, adrenal, liver, thymus, or thyroid after endosulfan treatment. These observations show that endosulfan treatment caused a significant decrease in compensatory ovarian hypertrophy. An increase in the number of atretic follicles and disruption of the estrous cycle may have been due to a direct effect on the ovary or to effects on the hypothalamo–hypophysial–ovarian axis.