Unbound MEDLINE

Prolactin regulates tuberoinfundibular dopamine neuron discharge pattern: novel feedback control mechanisms in the lactotrophic axis.

Abstract

Balance in the body's hormonal axes depends on feedback onto neuroendocrine hypothalamic neurons. This phenomenon involves transcriptional and biosynthetic effects, yet less is known about the potential rapid modulation of electrical properties. Here, we investigated this issue in the lactotrophic axis, in which the pituitary hormone prolactin is tonically inhibited by tuberoinfundibular dopamine (TIDA) neurons located in the hypothalamic arcuate nucleus. Whole-cell recordings were performed on slices of the rat hypothalamus. In the presence of prolactin, spontaneously oscillating TIDA cells depolarized, switched from phasic to tonic discharge, and exhibited broadened action potentials. The underlying prolactin-induced current is composed of separate low- and high-voltage components that include the activation of a transient receptor potential-like current and the inhibition of a Ca(2+)-dependent BK-type K(+) current, respectively, as revealed by ion substitution experiments and pharmacological manipulation. The two components of the prolactin-induced current appear to be mediated through distinct signaling pathways as the high-voltage component is abolished by the phosphoinositide 3-kinase blocker wortmannin, whereas the low-voltage component is not. This first description of the central electrophysiological actions of prolactin suggests a novel feedback mechanism. By simultaneously enhancing the discharge and spike duration of TIDA cells, increased serum prolactin can promote dopamine release to limit its own secretion with implications for the control of lactation, sexual libido, fertility, and body weight.

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  • Publisher Full Text
  • Authors

    Lyons DJ, Hellysaz A, Broberger C

    Institution

    Department of Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden. David.Lyons@ki.se

    Source

    The Journal of neuroscience : the official journal of the Society for Neuroscience 32:23 2012 Jun 6 pg 8074-83

    MeSH

    Action Potentials
    Animals
    Arcuate Nucleus
    Boron Compounds
    Calcium
    Data Interpretation, Statistical
    Dopamine
    Electrophysiological Phenomena
    Feedback, Physiological
    Female
    Indicators and Reagents
    Ion Channels
    Lactation
    Large-Conductance Calcium-Activated Potassium Channels
    Membrane Potentials
    Neurons
    Patch-Clamp Techniques
    Phosphatidylinositol 3-Kinases
    Prolactin
    Rats
    Rats, Sprague-Dawley

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    22674282