An analysis of factors responsible for resorption of embryos in cisplatin-treated rats.

Pregnant rats were injected ip with 4 or 7 mg cisplatin/kg on gestation day (gd) 6 to study its effect on embryonal resorption. Serum concentrations of prolactin, luteinizing hormone (LH), and progesterone were determined by radioimmunoassay in pregnant rats, and related to the effects of cisplatin on the maintenance of pregnancy. The nocturnal prolactin surge on gd 9 was abolished in cisplatin-treated rats. Within 3 days after drug injection, LH concentrations decreased 39%, while serum progesterone decreased 63% by Day 10. A histochemical study of 20 alpha-hydroxysteroid dehydrogenase activity revealed no enzyme activity by gd 10. It is proposed that the cause of cisplatin-related embryonal resorption in rats may be due to decreases in hormone concentrations observed after drug treatment.