AGEING AND OVARIAN Δ5-3β-HYDROXYSTEROID DEHYDROGENASE IN THE PREGNANT MOUSE

Abstract

SUMMARY Aged (12- to 14-month-old) C57BL oestrous mice exhibited significantly lower (P < 0·001) ovarian Δ5-3β-hydroxysteroid dehydrogenase (3β-HSD) concentration, specific activity and total content than young (3-month-old) oestrous mice, suggesting a decrease in the potential of the older animals to produce ovarian Δ4-3-oxosteroids. Mice in both age groups maintaining pregnancy to 10 or 18 days post coitum (p.c.) had similar values for activity of ovarian 3β-HSD. In the aged females in which foetal resorption had occurred, the majority of foetuses had been resorbed by 10 days p.c. However, ovarian 3β-HSD activity in these animals was not significantly different from that of young or aged mice maintaining pregnancy. By day 18, however, ovarian dehydrogenase activity in aged females failing to maintain pregnancy had decreased significantly. It is suggested that foetal death in aged mice is not the result of a deficiency in ovarian 3β-HSD, but rather may initiate luteal regression and consequently a decline in 3β-HSD.