Combined effects of vasoactive intestinal peptide and dopamine on adenylate cyclase in prolactin-secreting cells

D. Oliva, L. Vallar, G. Giannattasio, A. Spada, S. Nicosia

Research output: Contribution to journalArticlepeer-review

Abstract

VIP stimulates adenylate cyclase activity of male and female rat anterior pituitaries and human prolactinomas, while dopamine inhibits the enzyme activity of female rat pituitaries and prolactinomas. A dopamine inhibited cyclase can be detected also in male rats provided the enzyme activity is increased by VIP. The analysis of the dose-response curves for one agent (VIP or dopamine) in the absence or in the presence of the other indicates that the two agents exhibit a different pattern of interaction in the different systems. In fact, in female rat pituitaries and in human prolactinomas, the curves for dopamine±VIP and for VIP±dopamine were parallel, indicating that the two agents exherted their effects independently from one another. On the contrary, in male rat pituitaries, the curves were definitively non parallel, that is, the inhibitory effect of dopamine was greatly amplified by VIP. In no case was the apparent affinity (EC50) of one agent modified by the presence of the other. It is concluded that two different modes of interaction between stimulatory and inhibitory neurohormones might exist at the level of adenylate cyclase from anterior pituitary cells.

Original languageEnglish
Pages (from-to)1067-1070
Number of pages4
JournalPeptides
Volume5
Issue number6
DOIs
Publication statusPublished - 1984

Keywords

  • Adenylate cyclase
  • Dopamine
  • Mammotrophs
  • Prolactin
  • Prolactinoma
  • VIP

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Physiology
  • Cellular and Molecular Neuroscience

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