Inhibitory effects of putative dopamine D3 receptor agonists, 7-OH-DPAT and quinpirole, on prolactin secretion in rats.
The present experiments were performed to investigate effects of (+/-)-2-(dipropylamino)-7-hydroxy-1,2,3,4-tetrahydronaphthalene (7-OH-DPAT) or quinpirole (LY 171555), putative dopamine (DA) D3 receptor agonists, on serum prolactin levels in male rats. Basal prolactin levels were reduced dose-dependently by SC administration of 7-OH-DPAT or quinpirole at respective doses of 10-100 micrograms/kg and 25-250 micrograms/kg. Daily treatment with estradiol, 35 micrograms/kg/day for 3 days, increased serum prolactin levels to fourfold higher levels than those of nonprimed rats. Intraperitoneal injection of alpha-methyl-p-tyrosine (alpha-MT), 300 mg/kg, also increased serum prolactin levels. 7-OH-DPAT or quinpirole at a dose of 50 micrograms/kg caused a marked reduction in serum prolactin levels in both the estradiol- and alpha-MT-induced hyperprolactinemia. The 7-OH-DPAT- and quinpirole-induced decreases in serum prolactin levels were antagonized by the administration of the DA D2 receptor antagonist, spiperone, at 0.5 mg/kg. The results indicate that 7-OH-DPAT and quinpirole decrease prolactin levels in rats by stimulation of the D2 receptor.
Kurashima
M
M
Department of Obstetrics and Gynecology, Fukuoka University, Japan.
Domae
M
M
Inoue
T
T
Nagashima
M
M
Yamada
K
K
Shirakawa
K
K
Furukawa
T
T
D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D003864:Depression, Chemical; D018491:Dopamine Agonists / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D011388:Prolactin / Q000097:blood*; D019257:Quinpirole / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000187:drug effects*; D050637:Receptors, Dopamine D3; D013134:Spiperone / Q000494:pharmacology; D013239:Stereotyped Behavior / Q000187:drug effects; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors; D015000:Yawning / Q000187:drug effects; D019805:alpha-Methyltyrosine
D018491:Dopamine Agonists; D018492:Dopamine Antagonists; C493595:Drd3 protein, rat; D004791:Enzyme Inhibitors; D008781:Methyltyrosines; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D013764:Tetrahydronaphthalenes; D019257:Quinpirole; D004958:Estradiol; D013134:Spiperone; D019805:alpha-Methyltyrosine; D011388:Prolactin; D014446:Tyrosine 3-Monooxygenase; C031349:7-hydroxy-2-N,N-dipropylaminotetralin