Ovine Placental Steroid Synthesis and Metabolism in Late Gestation

The study investigated ovine placental steroid synthesis and metabolism during late gestation, focusing on enzyme activities and the effects of dietary intake and finasteride treatment. It found that dietary changes altered serum progesterone and estradiol levels but did not affect placental enzyme activities. Finasteride inhibited 5α-reduced progesterone metabolism without impacting serum progesterone levels. The study concluded that diet-induced changes in steroid concentrations were due to extra-placental metabolism, not altered placental synthesis, and that 5α-reduction was not a major determinant of systemic progesterone levels in late-gestation ewes. The findings underscored the complexity of placental steroid metabolism and its critical role in maintaining pregnancy and initiating parturition in sheep.