[The effect of progesterone and RU486 on progesterone production in the ovulatory process of rats].
To clarify the autoregulatory mechanism of progesterone (P) production in the ovulatory process, we examined the ovarian concentration of P 46 hrs after PMSG and the effects of P and RU486 (RU) injected 4-2 hrs before hCG administration on the serum concentrations of P and estradiol (E2), and ovarian 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activities in PMSG/hCG treated immature rats. The effect of RU on the number of ovulated ova was also studied. The ovarian concentration of P 46 hrs after PMSG was 0.96 +/- 0.03,ng/mg protein (mean +/- SEM). When P (100,mg/kg) was injected 2 hrs before hCG, ovarian 3 beta-HSD activities had significantly increased by 4 hrs after hCG. However, P at a dosage of 10 and 20,mg/kg had no effect on ovarian 3 beta-HSD activities. The administration of RU (20,mg/kg) 2 hrs before hCG significantly inhibited ovarian 3 beta-HSD activities measured 4 and 6 hrs after hCG (p less than 0.01 and p less than 0.05, respectively). In addition, the serum P concentration 4 hrs after hCG was significantly lower than that of the control (p less than 0.01). However, RU (20 mg/kg) in concomitant with hCG had no effect on ovarian 3 beta-HSD activities within 6 hrs after hCG. The suppression of ovarian 3 beta-HSD activities by RU was the concomitant reversed by the concomitant treatment with P (10 mg/kg). RU (10, 20, or 40 mg/kg) injected 2 hrs before hCG significantly reduced the number of ovulated ova (p less than 0.01, p less than 0.01 and p less than 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
Iwamasa
J
J
Department of Obstetrics and Gynecology, Kumamoto University Medical School.
D000818:Animals; D004958:Estradiol / Q000097:blood; D005260:Female; D006706:Homeostasis; D006913:Hydroxysteroid Dehydrogenases / Q000378:metabolism; D008297:Male; D015735:Mifepristone / Q000494:pharmacology*; D010053:Ovary / Q000378:metabolism*; D010060:Ovulation / Q000187:drug effects*; D011374:Progesterone / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains
D015735:Mifepristone; D011374:Progesterone; D004958:Estradiol; D006913:Hydroxysteroid Dehydrogenases