Anti-Implantation Action of Endosulfan in Albino Mice: Possible Mechanisms

Abstract

Endosulfan, a chlorinated pesticide, was administered orally for 7 consecutive days to a group of virgin pregnant albino mice at doses of 1 to 4 mg/kg/d to examine its effect on implantation. For comparison, a second group of animals received 5 microg/kg/d estradiol-17beta, a third group received similar quantities of olive oil. Autopsy on day 8 revealed that the olive oil-treated mice were pregnant with a normal number of implantations and a normal duration of diestrus. Treatment with estradiol-17beta completely inhibited implantation and significantly decreased the duration of diestrus with a concomitant increase in estrus. Treatment with 1, 2, or 3 mg/kg/d endosulfan neither inhibited implantation nor significantly changed diestrus, whereas 4 mg/kg/d endosulfan completely inhibited implantation, with the uterus showing no signs of implantation. This group exhibited a significant decrease in diestrus with a concomitant increase in estrus. In endosulfan-treated mice, no significant changes occurred in body and organ weight, except for a significant increase in uterine weight in groups treated with 4 mg/kg/d endosulfan or estradiol-17beta. Because endosulfan is neither tubal locking nor causes expulsion of the blastocyst from the uterus like estradiol-17beta, the pesticide might inhibit implantation by altering the estrogen-progesterone ratio essential for implantation.