Changes in Steroidogenesis by Isolated Rabbit Ovarian Follicles in Vitro during the Preovulatory Interval with Emphasis on Active Androgen Production
1977 年 24 巻 2 号 p. 129-137
詳細
1977 年 24 巻 2 号 p. 129-137
Transitory changes in steroidogenesis of isolated rabbit follicles during the course of ovulation were investigated. Follicles of 1 to 2 mm in diameter were mechanically dissected from ovaries of mature virgin rabbits before and 1, 2, 3, 6, 9 and 12 hours after intravenous injection of 100IU/kg of human chorionic gonadotropin (hCG). Five to ten follicles from a rabbit were incubated with 100μCi of acetate-1-14C at a time and eighty follicles were taken for each time. Incorporation of acetate-14C into pregnenolone, 17-hydroxypregnenolone, progesterone, 17-hydroxyprogesterone, 20α-dihydroprogesterone, dehydroepiandrosterone, androstenedione, testosterone, estrone and estradiol-17β was assessed by the reverse dilution technique with recrystallization to constant specific activity. Overall incorporation of acetate-14C into the ten steroids was at its maximum 3 hours after hCG injection, decreased gradually up to 9 hours and diminished to its minimum level at 12 hours. The highest incorporation into C21 and C18 steroids was observed 2 hours after hCG injection, while that into C19 steroids occurred 6 hours after it. Distribution patterns of incorporation among the individual steroids varied with time, although a preovulatory rise and fall in 14C incorporation was observed for all steroids analysed. Estradiol-17 β, testosterone and androstenedione were the major products in 0 hour follicles, while C21 steroids were predominant at the first 3 hours with 17-hydroxyprogesterone and pregnenolone the major products. C21 and C19 steroids were actively synthesized between 6 and 9 hours, when pregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone and testosterone were the principal steroids. At the 12th hour after hCG injection, the three androgenic steroids were clearly the major products. It was noted that active androgen production occurred during the latter half of the preovulatory interval.
