Interdependence of oestradiol and 5 alpha-dihydrotestosterone in modulating LH and FSH secretion in rats.
The effects of oestradiol, 5 alpha-dihydrotestosterone (DHT) and oestradiol plus DHT on pituitary responsiveness to LHRH were studied. Rats ovariectomized for 2 weeks were infused s.c. (by osmotic minipump) with LHRH at 250 ng/h for 6 days. Control rats received a sham s.c. pump. On day 3, silicone elastomer implants containing oestradiol or DHT were implanted s.c. and on day 6 the effects of these in-vivo treatments on pituitary LH and FSH content and on in-vitro (perifusion) LH and FSH secretion following maximal LHRH stimulation (1 microgram/ml perifusion medium) were assessed. Luteinizing hormone-releasing hormone alone decreased pituitary LH/FSH content and, in response to acute LHRH challenge in vitro, the absolute rate of LH/FSH release, but not LH/FSH release expressed as a fraction of pituitary content. Oestradiol alone increased pituitary LH/FSH content and LHRH-induced LH/FSH release in vitro, both absolutely and as a fraction of pituitary LH/FSH. Oestradiol exacerbated the decrease in pituitary LH/FSH caused by LHRH pretreatment in vivo, and decreased the absolute rate of LHRH-stimulated LH/FSH release in vitro, but increased this rate when it was expressed as a fraction of pituitary LH/FSH. In both LHRH-treated and control rats, DHT increased pituitary LH/FSH content, did not change the absolute rate of LH/FSH release in response to acute LHRH challenge in vitro, but decreased the rate of LH/FSH release expressed as a fraction of pituitary LH/FSH content.(ABSTRACT TRUNCATED AT 250 WORDS)
Schuiling
G A
GA
Department of Obstetrics and Gynaecology, University of Groningen, The Netherlands.
Moes
H
H
Koiter
T R
TR
D000818:Animals; D013196:Dihydrotestosterone / Q000494:pharmacology*; D004347:Drug Interactions; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000378:metabolism*; D010052:Ovariectomy; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D013196:Dihydrotestosterone; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone