Serotonin stimulates steroidogenesis in rat preovulatory follicles: involvement of 5-HT2 receptor.
The role of serotonin (5-HT) in the regulation of steroidogenesis in the ovary via 5-HT2 receptor was studied in normal cycling rats and their preovulatory follicles. Oral administration of ketanserin (KET), a selective 5-HT2 antagonist, at 10 mg/kg BW at 1100h on the day of proestrus resulted in a marked decrease in serum estradiol levels immediately after the administration. 5-HT stimulated estradiol secretion by preovulatory follicles incubated for 5 hrs in Krebs-Ringer bicarbonate buffer. 5-HT (2.5 microM) -enhanced estradiol secretion was inhibited by KET (1-100 microM) in a dose-dependent manner. Secretion of progesterone and testosterone was also inhibited by about the same order of magnitude as estradiol. Addition of pregnenolone (1 microgram/ml) prevented the KET-inhibited progesterone production. Both testosterone and estradiol increased at the same ratio by the addition of progesterone (1 microgram/ml). The inhibition of secretion of these hormones was overcome by dbcAMP (0.1 mM). The present study suggests that 5-HT stimulates steroidogenesis in the metabolic pathway prior to pregnenolone in rat preovulatory follicles and the action of 5-HT could possibly be mediated by a 5-HT2 receptor.
Tanaka
E
E
Toxicology Laboratory, Mitsubishi Kasei Corporation, Yokohama, Japan.
Baba
N
N
Toshida
K
K
Suzuki
K
K
D000818:Animals; D004958:Estradiol / Q000378:metabolism*; D005260:Female; D005498:Follicular Phase / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007650:Ketanserin / Q000494:pharmacology; D011284:Pregnenolone / Q000494:pharmacology; D011374:Progesterone / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism
D011985:Receptors, Serotonin; D012701:Serotonin; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D011284:Pregnenolone; D007650:Ketanserin