Secretion of pregnane compounds from follicular and luteal ovaries in rats

Differences during the follicular and luteal phases in the secretion of pregnane compounds by rat ovaries were studied. Daily s.c. injections of 2 mg of progesterone that began at early diestrus prolonged the diestrus stage for the duration of the treatment. In the follicular phase, normal proestrus and proestrus delayed by progesterone treatment were examined. In the luteal phase, day 6 of pseudopregnancy was examined. 20 alpha-hydroxy-4-pregnen-3-one accounted for most of total amount of pregnane compounds secreted from ovaries in the follicular phase, and progesterone and 20 alpha-hydroxy-4-pregnen-3-one for most at the luteal phase. The levels of 5 alpha-pregnane compounds were low in both phases. Injection of 2 micrograms of luteinizing hormone (LH) before sample collection increased the secretion of progesterone in the follicular phase, but not in the luteal phase. The secretion of 5 alpha-pregnane-3,20-dione and 3 alpha-hydroxy-5 alpha-pregnan-20-one was increased by the injection of LH in either phase, but the ability of the ovaries to produce these steroids was low, suggesting that there was low 5 alpha-reductase activity in the ovaries of rats with delayed proestrus and pseudopregnant rats.