title: Nitric oxide reverses prostaglandin-induced inhibition in ovarian progesterone secretion in rats.
abstract: The present studies were undertaken to determine whether nitric oxide (NO) is involved in the regulation of ovarian progesterone and oestradiol secretion in rats. Immature female Sprague-Dawley rats at 27 days of age were injected s.c. with 4 IU pregnant mare's serum gonadotrophin (PMSG) and were killed 72 h after the injection. The ovaries were collected, weighed and cultured in Dulbecco's modified Eagle's medium containing saline, NO donor, NO synthesis inhibitor or prostaglandin F2 alpha (PGF2 alpha). After 24 h culture, the medium concentrations of progesterone and oestradiol were measured by radioimmunoassay. Results showed that: (i) diethylenetriamine (DETA)/NO (1 x 10(-6), 1 x 10(-5), 1 x 10(-4) M), an NO donor, caused a dose-dependent increase in progesterone synthesis (355 +/- 43, 443 +/- 46, 647 +/- 55 ng/g ovary respectively, P < 0.01) with a concomitant decrease in ovarian oestradiol secretion (408.1 +/- 50.7, 272.9 +/- 28.2, 132.6 +/- 34.6 pg/g ovary respectively, P < 0.01); (ii) neither progesterone nor oestradiol concentrations in the culture medium were altered by DETA without NO; (iii) NG-nitro-l-arginine methyl ester (1 x 10(-4) M), an inhibitor of NO synthesis, did not significantly affect progesterone and oestradiol secretion by rat ovaries; (iv) PGF2 alpha(1 x 10(-6) M) caused a fall in progesterone and oestradiol synthesis; (v) co-incubation with DETA/NO, significantly reversed the PGF2 alpha-induced decrease in progesterone concentrations from 184 +/- 29 to 388 +/- 60 ng/g (P < 0.01), but not that of oestradiol. It can be concluded that NO up-regulates progesterone secretion and down-regulates oestradiol secretion in rat ovaries, and NO can reverse PGF2 alpha-induced inhibition in ovarian progesterone secretion.
authors.affiliation: Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston 77555, USA.
authors.forename: Y L
authors.initials: YL
authors.lastname: Dong
authors.forename: P R
authors.initials: PR
authors.lastname: Gangula
authors.forename: L
authors.initials: L
authors.lastname: Fang
authors.forename: C
authors.initials: C
authors.lastname: Yallampalli
mesh_terms: D000818:Animals; D015237:Dinoprost / Q000494:pharmacology*; D004958:Estradiol / Q000096:biosynthesis; D005260:Female; D009569:Nitric Oxide / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010053:Ovary / Q000378:metabolism*; D011073:Polyamines / Q000494:pharmacology; D011374:Progesterone / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D011073:Polyamines; C005391:diethylenetriamine; D009569:Nitric Oxide; D011374:Progesterone; D004958:Estradiol; D015237:Dinoprost