Ovarian Progestins, Androgens and Estrogen Throughout the 4-Day Estrous Cycle in the Rat

Abstract

Groups of female rats were sacrificed throughout the 4-day estrous cycle and the ovaries assayed for pregnenolone, progesterone, 17-OH-progesterone, 17-OH-pregnenolone, androst-5-ene-3.beta.,17.beta.-diol, androstenedione, testosterone, dihydrotestosterone, androstane-3.alpha., 17.beta.-diol, androstane-3.beta.,17.beta.-diol and estradiol. Ovarian progesterone levels were relatively high throughout the estrous cycle while ovarian 17-OH-progesterone, androstenedione, testosterone and estradiol levels increased progressively to about 20-fold throughout the cycle and reached maximal levels on the afternoon of proestrus. Dihydrotestosterone, androstane-3.alpha.,17.beta.-diol and androstane-3.beta.,17.beta.-diol concentrations increased only 2- to 3-fold throughout the 4-day cycle. The ovary evidently secretes high levels of androgen precursors which are further aromatized to estradiol.