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Horm Metab Res 1991; 23(5): 213-217
DOI: 10.1055/s-2007-1003656
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© Georg Thieme Verlag, Stuttgart · New York

α2-Adrenoceptor-Mediated Inhibition of Prolactin Release in Suckling- or Fenfluramine-Induced Hyperprolactinemia

P. Navarra2 , W. Eechaute1 , P. Preziosi2 , E. Lacroix1
  • 1Laboratory of Normal and Pathological Physiology, State University of Ghent, Ghent, Belgium
  • 2Department of Pharmacology, Catholic University School of Medicine, Rome, Italy
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Publication History

1990

1990

Publication Date:
14 March 2008 (online)

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Summary

It has recently been shown that the specific and selective α2-antagonist idazoxan (IDZ) displays prolactin-lowering activity on hyperprolactinemia induced in the rat either by suckling or serotonergic drugs. In an attempt better to understand the role of α2-adrenoceptors under the above conditions, experiments were carried out to compare the effects of IDZ with that of the classic α2-antagonist yohimbine (YOH), and also of the α2-agonist sclonidine (CLO) and B-HT 920, on prolactin (PRL) release during lactation and in hyperprolactinemia induced in male rats by the serotonergic drug fenfluramine (FEN).

In lactating rats, both α2-agonists decreased PRL release; this effect was enhanced by prior separation of the animals from their pups for several hours. A decrease of plasma PRL levels was also induced by IDZ but not by YOH, which tended further to increase hyperprolactinemia. In male rats treated with FEN, IDZ and CLO, a significant decrease of plasma PRL was produced, but YOH further enhanced PRL secretion.

It is concluded that the α2-agonists tested and also the α2-antagonist IDZ display a unique inhibitory activity on PRL release during suckling or serotonergic-induced hyperprolactinemia.

Key words

α2-Adrenoceptors - Prolactin - Lacation