Dopaminergic Inhibition of Anterior Pituitary Adenylate Cyclase Activity and Prolactin Release: The Effects of Perturbing Calcium on Catalytic Adenylate Cyclase Activity
作者:
Gennaro Schettini,
Eric L. Hewlett,
Michael J. Cronin,
Koji Koike,
Takeshi Yasumoto,
Robert M. MacLeod,
期刊:
Neuroendocrinology
(Karger Available online 1986)
卷期:
Volume 44,
issue 1
页码: 1-7
ISSN:0028-3835
年代: 1986
DOI:10.1159/000124613
出版商: S. Karger AG
关键词: Dopamine;Adenylate cyclase;Prolactin;Calcium;cAMP
数据来源: Karger
摘要:
The dopaminergic inhibition of anterior pituitary adenylate cyclase activity, cAMP accumulation, and prolactin release was studied in the presence of the Ca2+ channel activator, maitotoxin. In isobutylmethylxanthine (IBMX)-treated cells, maitotoxin stimulated prolactin secretion within 30 s and cAMP accumulation within 1 min. Although dopamine reduced cAMP accumulation and prolactin release, the effectiveness of the catecholamine was reduced in the presence of maitotoxin. When hemipituitary glands were exposed for 10 min to 100 ng maitotoxin/ml, their membranes showed increased adenylate cyclase activity. The hypothesis that maitotoxin stimulates adenylate cyclase activity by increasing Ca2+ availability was supported by the observation that, at concentrations up to 100 µM, Ca2+ stimulated anterior pituitary adenylate cyclase acitivity. Although dopamine decreased basal and maitotoxin-stimulated pituitary cAMP accumulation, via changes in adenylate cyclase activity, the decrement in cyclic nucleotide production, but not prolactin release, can be ascribed to the effect of the catecholamine on the basal activities of these parameters. These data provide additional evidence that an increased Ca2+ flux is stimulating to cAMP generation and prolactin release, whereas dopamine is inhibitory to these processes
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