Steroid Metabolism in the Corpus Luteum of the Ferret

Implantation in the ferret is believed to be induced by a luteal substance which acts in concert with progesterone (P4) and which is secreted sometime between Days 6 and 8 of pregnancy. This experiment was designed to identify the steroid products synthesized by ferret corpora lutea (CL) on these 2 days of pregnancy. CL were dissected from ferrets on Day 6 or 8 of pregnancy and incubated with 3 HI preg-nenolone (P3), (3H1 P4, or [3H1 dehydroepiandrosterone (DHEA). Controls with no tissue or with 50 l packed blood cells were incubated at the same time. After incubation of Day 6 CL with [3H1P3 for 180 mm, 39 % of the added label was found incorporated into P4, 3 % into 17a-hy-droxyprogesterone (1 7a-OHP4) and 1 % into androstenedione (A). Incubation of Day 8 CL with the same precursor resulted in 35%, 1 % and 0.65 % of the label being incorporated into the pre-viously mentioned products, respectively. Incubations of Days 6 and 8 ferret CL with 3 HIP4 or [3 HI DHEA confirmed these results, demonstrating activity of C21-steroid, 1 7o-hydroxylase and -isomerase, 3j3-hydroxysteroid dehydrogenase (3j3-HSD). These results suggest that ferret CL primarily accumulate steroids of the L ’ pathway on both Days 6 and 8 of pregnancy, with P4, 17n-OHP4, A and testosterone (T) being the most abundant products after in vitro incubation. Thus, ferret CL appear to metabolize steroids in a manne