Data/hora: 22/06/2024 07:17:41

Biblioteca(s): | Embrapa Caprinos e Ovinos.
Data corrente: | 22/06/2017
Data da última atualização: | 22/06/2017
Autoria: | THOMAS, G. B.; CUMMINIS, J. T.; DOUGHTON, B. W.; GRIFFIN, N.; SMYTHE, G. A.; GLEESON, R. M.; CLARKE, I. J.
Título: | Direct pituitary inhibition of prolactin secretion by dopamine and noradrenaline in sheep.
Ano de publicação: | 1989
Fonte/Imprenta: | Journal of Endocrinology, v. 123, n. 3, p. 393-402, Dec. 1989.
DOI: | 10.1677/joe.0.1230393
Idioma: | Inglês
Conteúdo: | Abstract: The effects of dopamine, noradrenaline and 3,4-dihydroxyphenylacetic acid (DOPAC) on the release of prolactin were examined in ovariectomized ewes. Infusion of dopamine (0.5 or 1 microgram/kg per min for 2 h i.v.) reduced plasma prolactin concentrations in a dose-dependent manner, whereas DOPAC (5 or 10 micrograms/kg per min for 2 h i.v.) had no effect. In a further series of experiments, ovariectomized hypothalamopituitary disconnected ewes were given dopamine or noradrenaline (each at 0.5 or 1 microgram/kg per min for 2 h i.v.), and both amines reduced mean plasma concentrations of prolactin with similar potency in a dose-dependent manner. These effects were blocked by treatment with pimozide and prazosin respectively. During the infusion of dopamine, the peripheral plasma concentrations of DOPAC and 3,4-dihydroxyphenylethyleneglycol (DHPG) were increased (DOPAC, 22 +/- 7 (S.E.M.) to 131 +/- 11 nmol/l; DHPG, 2.9 +/- 0.3 to 6.4 +/- 0.2 nmol/l), but plasma concentrations of dopamine and noradrenaline did not change. Finally, administration of domperidone, a specific dopamine receptor antagonist that does not cross the blood-brain barrier, resulted in a sustained increase in plasma prolactin concentrations in ovariectomized ewes. We conclude that the secretion of prolactin from the pituitary gland is under dual inhibitory regulation by both dopamine and noradrenaline in the sheep.
Palavras-Chave: | 3-4-Dihydroxyphenylacetic Acid.
Thesaurus Nal: | Dopamine; Norepinephrine; Pharmacology; Pituitary Gland; Prolactin; Secretion; Sheep.
Categoria do assunto: | L Ciência Animal e Produtos de Origem Animal
Registro original: | Embrapa Caprinos e Ovinos (CNPC)
Exemplares: | CNPC - (33922-1) - ADD - AP - PP -  -  -  - DIS