Sexual differences in the effect of serotonin on LH secretion in rats.
The effect of 5-hydroxytryptophan (5-HTP), a serotonin (5-HT) precursor, on luteinizing hormone (LH) secretion was studied in prepubertal male and female rats of different ages. In females 5-HTP stimulated LH release on days 16, 18 and 20 but not in older rats (26, 30, 35 days of age). No effects of 5-HTP on LH levels were observed in males. The positive feed-back mechanism of oestrogen-progesterone (E-P), that normally matures in the female between 20 and 26 days, was inhibited by 5-HTP in all the ages studied during prepuberty (26, 30 and 35 days old). On the other hand, in adult ovariectomized rats, 5-HTP administration not only decreased the high LH levels induced by ovariectomy, but the LH release response to E-P as well. These results indicate that there are sexual differences in the effect of 5-HT on LH in prepubertal rats younger than 26 days old. Administration of p-chloroamphetamine (PCA) a serotonin neurotoxin selective for serotoninergic neurons that depletes 5-HT levels in the brain, induced a significant increase in the LH release response to LRH in females, but had no effect in males. These results, besides suggesting a probable pituitary participation in the 5-HT action on LH secretion in the female, appear to indicate the existence of sexual differences in the effect of 5-HT in adult rats.
Moguilevsky
J A
JA
Faigón
M R
MR
Rubio
M C
MC
Scacchi
P
P
Szwarcfarb
B
B
D006916:5-Hydroxytryptophan / Q000494:pharmacology*; D000818:Animals; D002369:Castration; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007031:Hypothalamus / Q000378:metabolism; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D008694:Methamphetamine / Q000494:pharmacology; D010902:Pituitary Gland / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology*; D012737:Sex Factors; D012741:Sexual Maturation
D012701:Serotonin; D007987:Gonadotropin-Releasing Hormone; D008694:Methamphetamine; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D006916:5-Hydroxytryptophan