Evaluation of Early Embryonic Loss Induced by Tributyltin Chloride in Rats: Phase- and Dose-Dependent Antifertility Effects

Abstract.

In our previous study, tributyltin chloride (TBTCl) on days 0–7 of pregnancy was found to produce implantation failure in rats. The objective of the present study was to determine the susceptible period for the antifertility effect of TBTCl in rats. Inseminated females were orally administered TBTCl at 8.1, 16.3, or 32.5 mg/kg on days 0–3 of pregnancy, or at 8.1, 16.3, 32.5, or 65.1 mg/kg on days 4–7 of pregnancy. Pregnancy outcome was determined on day 20 of pregnancy. Dosing with TBTCl on days 0–3 of pregnancy at 16.3 mg/kg and higher produced a significant increase in the rate of implantation failure. Dosing with TBTCl on days 4–7 of pregnancy caused a significant increase in the incidence of postimplantation loss at 16.3 mg/kg and higher in females with implantations. No increase in the incidence of fetal malformations was found in any TBTCl-treated groups. It could be concluded that the susceptibility to and manifestation of the antifertility effects of TBTCl vary with the gestational stage at the time of administration.