Suppression of decidual cell response induced by tributyltin chloride in pseudopregnant rats: a cause of early embryonic loss

In our previous studies, tributyltin chloride (TBTCl) at doses of 16.3 mg/k g and above caused implantation failure (preimplantation embryonic loss) an d postimplantation embryonic loss in rats following administration on gesta tional day (GD) 0 through GD 3 and GD 4 through GD 7, respectively. This st udy was designed to assess the effects of TBTCl on uterine function as a ca use of early embryonic loss in pseudopregnant rats. TBTCl was given orally to pseudopregnant rats at doses of 4.1, 8.1, 16.3 and 32.5 mg/kg on pseudop regnant day (PPD) 0 to PPD 3 or 8.1, 16.3, 32.5 and 65.1 mg/kg on PPD 4 to PPD 7. The decidual cell response was induced by bilateral scratch trauma o n PPD 4. The uterine weight on PPD 9 served as an index of uterine decidual ization. Uterine weight and serum progesterone levels on PPD 9 were signifi cantly decreased after administration of TBTCl at doses of 16.3 mg/kg and a bove on PPD 0 to PPD 3 or PPD 4 to PPD 7. Administration of TBTCl at doses of 8.1 mg/kg and above on PPD 0 to 3 also significantly decreased serum pro gesterone levels on PPD 4. TBTCl had no effect on ovarian weight and number of corpora lutea. It can be concluded that TBTCl suppresses the uterine de cidual cell response and decreases progesterone levels, and these effects a re responsible for early embryonic loss due to TBTCl exposure.