1
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found

      Estradiol rapidly stimulates dopamine release from the posterior pituitary in vitro.

      1 ,

      Neuroendocrinology

      S. Karger AG

      Read this article at

      ScienceOpenPublisherPubMed
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Dopamine (DA) from both the posterior pituitary (PP) and stalk-median eminence (SME) inhibits prolactin (PRL) secretion from the anterior pituitary. Estradiol participates in the regulation of PRL release, in part by modulating DA release from the SME. However, little is known concerning the effects of estradiol on the release of DA from the PP. The objective of this study was to examine whether estradiol rapidly affects the potassium-evoked release of endogenous DA from the PP and SME in vitro. Tissues were dissected from ovariectomized rats and allowed to equilibrate in media for 30 min. Two pulses of 28 mM K+, 3 min each, were then given 30 min apart. Test substances were added 20 min before the second stimulus. DA in the media was determined by HPLC. Estradiol, at a concentration of 1 and 10 nM, significantly stimulated the potassium-evoked DA release from the PP by 34 and 47%, respectively. This stimulation was specific since 17 alpha-estradiol, a biologically inactive isomer, and testosterone, were without effects. Estradiol did not alter DA release from either the SME or isolated neural lobes of the PP. Naloxone, an opioid receptor antagonist, abolished the estradiol-induced stimulation of DA release from the PP. In contrast, amphetamine, a DA-releasing agent, significantly increased DA release in the presence of naloxone. In conclusion, (1) estradiol stimulates DA release from the PP but not the SME or neural lobe; this effect is rapid and stereospecific, and (2) the effects of estradiol appear to be mediated via an opioid(s) peptide(s) from the intermediate lobe.

          Related collections

          Author and article information

          Journal
          Neuroendocrinology
          Neuroendocrinology
          S. Karger AG
          0028-3835
          0028-3835
          Jun 1991
          : 53
          : 6
          Affiliations
          [1 ] Department of Physiology and Biophysics, Indiana University School of Medicine, Indianapolis.
          Article
          10.1159/000125780
          1876237

          Comments

          Comment on this article