Infusion of Dopamine at Low Concentrations Stimulates the Release of Prolactin from α-Methyl-p-Tyrosine-Treated Rats

Abstract Prolactin (PRL) secretion from the anterior pituitary gland is inhibited by dopamine (DA) released into the hypophysial portal vasculature from neurons in the hypothalamus. We have shown previously that DA also stimulates PRL secretion in vitro. Here we report that DA has a dual effect on PRL release in vivo. Injection of rats with α-methyl-p-tyrosine (200 mg/kg, ip) induced an immediate 35-fold enhancement of PRL secretion which reached a plateau by 90 min after injection on diestrus 1. When DA was infused intravenously at varying doses beginning at 90 min after α-methyl-p-tyrosine, differing effects on PRL secretion were observed. These effects were dose dependent: higher doses of DA (1000 ng/kg/min) inhibited and lower doses (10 ng/kg/min) stimulated PRL secretion. These data suggest that DA may be an important stimulator of PRL secretion in vivo.

[1]  J. D. Neill,et al.  Dopamine levels in hypophysial stalk plasma of the rat during surges of prolactin secretion induced by cervical stimulation. , 1979, Endocrinology.

[2]  L. Frawley,et al.  Suckling unmasks the stimulatory effect of dopamine on prolactin release: possible role for alpha-melanocyte-stimulating hormone as a mammotrope responsiveness factor. , 1991, Endocrinology.

[3]  S. Shin.  Dopamine-induced inhibition of prolactin release from cultured adenohypophysial cells: spare receptors for dopamine. , 1978, Life sciences.

[4]  Carl Denef,et al.  Dopaminergic stimulation of prolactin release , 1980, Nature.

[5]  J. D. Neill,et al.  The effect of dopamine on thyrotropin-releasing hormone-induced prolactin secretion in vitro. , 1981, Endocrinology.

[6]  D. Sibley,et al.  Agonist interactions with dopamine receptors: focus on radioligand-binding studies. , 1984, Federation proceedings.

[7]  N. Ben-Jonathan,et al.  Neuroendrocrine regulation of prolactin release , 1989, Progress in Neurobiology.

[8]  C. Oliver,et al.  Dopamine in hypophysial portal plasma of the rat during the estrous cycle and throughout pregnancy. , 1977, Endocrinology.

[9]  J. D. Neill,et al.  Dopamine levels in hypophysial stalk blood in the rat are sufficient to inhibit prolactin secretion in vivo. , 1978, Endocrinology.

[10]  S. Snyder,et al.  3H-Spiroperidol labels dopamine receptors in pituitary and brain. , 1977, European journal of pharmacology.

[11]  R. Macleod,et al.  Prolactin and growth hormone production as influenced by catecholamines and agents that affect brain catecholamines. , 1970, Neuroendocrinology.

[12]  W. Daughaday,et al.  Catecholamine inhibition of prolactin secretion by isolated rat adenohypophyses. , 1970, Endocrinology.

[13]  P. Plotsky,et al.  The decrease in hypothalamic dopamine secretion induced by suckling: comparison of voltammetric and radioisotopic methods of measurement. , 1982, Endocrinology.

[14]  B. Arey,et al.  A sex-specific endogenous stimulatory rhythm regulating prolactin secretion. , 1989, Endocrinology.

[15]  I. Kramer,et al.  Studies on the kinetics of dopamine-regulated prolactin secretion , 1982, Molecular and Cellular Endocrinology.

[16]  J. D. Neill,et al.  Dopamine levels in the anterior pituitary gland monitored by in vivo electrochemistry , 1986, Brain Research.

[17]  T. Burris,et al.  Pharmacologic evidence that a D2 receptor subtype mediates dopaminergic stimulation of prolactin secretion from the anterior pituitary gland. , 1991, Neuroendocrinology.

[18]  J. Sterman,et al.  Ovarian steroid modulation of prolactin surges in cervically stimulated ovariectomized rats. , 1978, Endocrinology.

[19]  G. Brown,et al.  Dopamine/neuroleptic receptors in basal hypothalamus and pituitary. , 1976, Endocrinology.

[20]  P. Plotsky,et al.  Dopamine levels in hypophysial stalk plasma and prolactin levels in peripheral plasma of the lactating rat: effects of a simulated suckling stimulus. , 1981, Neuroendocrinology.