Effects of thyrotropin-releasing hormone analogues on body shaking and prolactin levels in estrogen-primed and nonprimed rats.
The effects of a thyrotropin-releasing hormone (TRH) analogue, MK-771, in comparison with TRH and another TRH analogue, DN-1417, on body shaking and prolactin secretion were investigated in estrogen-primed and nonprimed rats. Intraperitoneal injections of TRH (20, 40 mg/kg), MK-771 (0.5-4 mg/kg) or DN-1417 (5-20 mg/kg) elicited marked body shaking in male rats. MK-771-induced shaking did not increase upon daily administration of the drug (0.5 mg/kg, s.c.) for 20 days or after treatment with estradiol benzoate (35 micrograms/kg, s.c.) for a 3 days period. Furthermore, following daily administration of MK-771 (0.5 mg/kg, s.c.) for 20 days, serum prolactin levels remained unchanged in male rats. Behaviorally active doses of TRH (20 mg/kg, i.p.), MK-771 (2 mg/kg, i.p.) and DN-1417 (10 mg/kg, i.p.) also failed to elevate serum prolactin levels in both ovariectomized rats and normal male rats. These drugs did, however, markedly elevate prolactin levels which had been increased in estrogen-primed male rats. The results suggest that TRH, MK-771 and DN-1417, in behaviorally active doses, exert a marked endocrine effect on prolactin secretion in estrogen-primed rats, but not in ovariectomized rats or normal male rats.
Yamada
K
K
Department of Pharmacology, School of Medicine, Fukuoka University, Japan.
Kumagai
M
M
Nagashima
M
M
Matsuo
N
N
Furukawa
T
T
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D000928:Antidepressive Agents / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D010052:Ovariectomy; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D053778:Thiazolidines; D013973:Thyrotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000494:pharmacology*
D000927:Anticonvulsants; D000928:Antidepressive Agents; D004967:Estrogens; D053778:Thiazolidines; D004958:Estradiol; D013973:Thyrotropin-Releasing Hormone; C021597:pyro(l-alpha-aminoadipyl)-L-histidyl-L-thiazolidine-4-carboxamide; D011388:Prolactin; C029762:DN 1417