[Effects of iontophoretically-applied LHRH, TRH, estrogen and clomiphene on thermo-sensitive neurons in the rat hypothalamus].
Studies were performed on the correlation between the hypothalamic temperature-sensitive neurons and hypothalamic neurons sensitive to LHRH, TRH, conjugated estrogen and clomiphene in 103 castrated matured female rats by the technique of microiontophoresis using a multi-barrel glass microelectrode. Out of 348 neurons in the hypothalamus, 24 neurons were found to be LHRH-sensitive, 20 TRH-sensitive, 41 estrogen-sensitive, and 18 clomiphene-sensitive. There were 19(28.8%) warm-sensitive and 11(16.7%) cold-sensitive neurons located in the preoptic area. From among the 19 warm-sensitive neurons, 14 neurons showed excitation by estrogen and 4 showed suppression by LHRH. Out of the 11 cold-sensitive neurons, estrogen, LHRH, and TRH excited 4, 3, and 3 neurons, respectively. It is suggested from these studies that LHRH mainly exhibits its thermo-regulatory functions by exciting warm-sensitive neurons and it is for this reason that exogenous estrogens are effective in alleviating hot flushes in natural as well as post-operative menopause which are thought to be caused by LHRH.
D000200:Action Potentials; D000818:Animals; D002369:Castration; D002996:Clomiphene / Q000494:pharmacology*; D045166:Estradiol Congeners / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007031:Hypothalamus / Q000502:physiology*; D007478:Iontophoresis; D051381:Rats; D011919:Rats, Inbred Strains; D013823:Thermoreceptors / Q000187:drug effects*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D045166:Estradiol Congeners; D002996:Clomiphene; D007987:Gonadotropin-Releasing Hormone; D013973:Thyrotropin-Releasing Hormone