Effects of postnatal corticosterone treatment on reproductive development in the rat

Reproductive development was studied in rats in which corticosterone (25 mg/100 g body wt) mixed with an equal amount of cholesterol was implanted i.p. at Days 3, 6, 12 or 18 after birth. Vaginal perforation in rats treated on Days 12 or 18 was advanced by 10 days but reproductive function in the treated animals was generally disrupted. A variable incidence of persistent vaginal oestrus was observed in adult females given implants on Days 3 and 6, and of prolonged vaginal dioestrus in those treated on Days 12 or 18. All treated females had lordosis quotients lower than those of untreated controls, the effect being most pronounced at the earlier ages of treatment. The results are believed to indicate two periods in reproductive development which are differentially affected by corticosterone.