GABA acts directly on cells of pituitary pars intermedia to alter hormone output

  title={GABA acts directly on cells of pituitary pars intermedia to alter hormone output},
  author={S. A. Tomiko and P. S. Taraskevich and W. Douglas},
Recent immunohistochemical evidence from the rat, indicating that γ-aminobutyric acid (GABA)-containing fibres of central nervous origin project to the pars intermedia of the pituitary1,2, prompts inquiry into the function of this innervation. There is electrophysiological evidence that GABA acts directly on melanotrophs isolated from rat, through bicuculline-blockable receptors, to increase Cl− conductance and thereby drive the membrane potential towards the Cl− equilibrium potential in these… Expand
Modulation of GABAA Receptor Channels and Calcium Currents in Cultured Porcine Melanotrophs a
The endocrine cells of the intermediate lobe (IL) of the pituitary gland have been used in our and other laboratories in order to study the mechanisms involved in excitation-secretion coupling andExpand
GABAergic regulation of melanocyte-stimulating hormone secretion from the pars intermedia of Xenopus laevis: immunocytochemical and physiological evidence.
The results indicate that GABA is a physiologically important factor for regulation of the pars intermedia in Xenopus laevis. Expand
GABA and Dopamine Act Directly on Melanotropes of Xenopus to inhibit MSH secretion
Both the neurotransmitters dopamine and gamma-aminobutyric acid (GABA), which are thought to be physiologically important MSH-release inhibiting factors, were shown to inhibit MSH release from isolated melanotropes. Expand
Ionic Movements Related to GABA Action on Neurosecretory Fibers and Endocrine Cells of the Hypophyseal Neurointermediate Lobe
Many biochemical and physiological data show that GABA has an inhibitory role in modulating neurotransmitter and hormone release. Current concepts hold that this action is mediated via a dualExpand
Regulation of cyclic-AMP synthesis in amphibian melanotrope cells through catecholamine and GABA receptors.
During in vitro incubation of isolated melanotrope cells it was found that dopamine, adrenaline and LY 171555 induced inhibition of forskolin-stimulated cAMP production and concomitantly inhibited MSH release. Expand
Novel synaptic responses mediated by dopamine and γ-aminobutyric acid in neuroendocrine cells of the intermediate pituitary
Neuroendocrine cells of the pituitary pars intermedia contain pro-opiomelanocortin and secrete mainly alpha-melanocyte-stimulating hormone and, in lesser amounts, corticotropin and endorphin. We haveExpand
GABAA and GABAB receptors on porcine pars intermedia cells in primary culture: Functional role in modulating peptide release
The patch-clamp technique has been used to demonstrate the presence of gamma-aminobutyrateA (GABAA) receptors on porcine pars intermedia cells, and the effects of specific agonists for each receptor were tested on peptide release from cells maintained in a perfusion system. Expand
Modulation of GABAA receptors and neuropeptide secretion by the neurosteroid allopregnanolone in posterior and intermediate pituitary.
Allopregnanolone in physiological relevant concentrations modulates GABAA receptors in both the posterior and intermediate lobes, but only affects hormone release in the posterior lobe. Expand
Electrophysiological evidence for the existence of GABAA receptors in cultured frog melanotrophs
The results indicate that the rapid and transient stimulation of alpha-MSH release induced by GABA can be accounted for by activation of a chloride conductance which causes membrane depolarization which provokes activation of voltage-operated calcium channels. Expand
Ionic conductances related to GABA action on secretory and biosynthetic activity of pars intermedia cells
Both GABA-B receptor activation and use of calcium deficient medium inhibited peptide release from IL cells, and removal of calcium from the culture medium or long-term incubation with 10 microM GABA or muscimol significantly reduced POMC mRNA levels. Expand


GABA directly affects electrophysiological properties of pituitary pars intermedia cells
The brain can influence the endocrine cells of the pars intermedia directly through GABAergic mechanisms, and the ionic and pharmacological characteristics of this action of GABA resemble those encountered at many GABAergic synapses in the central nervous system (CNS). Expand
Potassium-induced secretion of melanocytestimulating hormone from isolated pars intermedia cells signals participation of voltage-dependent calcium channels in stimulus-secretion coupling
It is concluded that activation of voltage-dependent Ca channels in pars intermedia cells allows influx of Ca ions that provides an adequate stimulus for MSH secretion and encourages the view that electrical activity in these cells is involved in the regulation of secretion. Expand
Identification of MSH release-inhibiting elements in the neurointermediate lobe of the rat
It is concluded that the K+-induced inhibition of MSH release is mediated by DA rather than by neuropeptides from terminals in the neurointermediate lobe, in agreement with the proposedMSH release-inhibiting role of the dopaminergic tuberoinfundibular neurones. Expand
Release of α-Melanocyte-Stimulating Hormone from Dispersed Cells of the Intermediate Lobe of the Rat Pituitary Gland: Involvement of Catecholamines and Adenosine 3′,5′-Monophosphate
Treatment of the neurointermediate lobe of the rat pituitary gland with mechanical agitation in the presence of trypsin and DNAse results in a preparation of cells which secrete αMSH and synthesizeExpand
Central GABAergic innervation of neurointermediate pituitary lobe: biochemical and immunocytochemical study in the rat.
  • W. Oertel, E. Mugnaini, +4 authors I. Kopin
  • Biology, Medicine
  • Proceedings of the National Academy of Sciences of the United States of America
  • 1982
Activity of glutamic acid decarboxylase GluDCase, the biosynthetic enzyme of gamma-aminobutyric acid (GABA) was measured in low-speed homogenate supernatant of the neural and intermediateExpand
Calcium component to action potentials in rat pars intermedia cells.
The demonstration of a Ca component to the predominantly Na‐dependentaction potentials of pars intermedia cells heightens the possibility that these action potentials participate in the regulation of secretion. Expand
GABA neuron systems in hypothalamus and the pituitary gland. Immunohistochemical demonstration using antibodies against glutamate decarboxylase.
The distribution of gamma-aminobutyric acid nerve fibers and cell bodies in the rat hypothalamus and pituitary gland was immunohistochemically examined and provided a morphological basis by which GABA of hypothalamic origin may regulate the neuroendocrine system. Expand
The results demonstrate that function and morphologic integrity are preserved in this cell system, suitable for the study of various aspects of pituitary secretion and its control. Expand
Coordinated action of calcium ion and adenosine 3',5'-monophosphate upon the release of alpha-melanocyte-stimulating hormone from the intermediate lobe of the rat pituitary gland.
The results indicate that Ca++ is essential for the release of alpha MSH, and that cAMP in some way enhances the effects of Ca++ upon the release process. Expand
Action potentials in gland cells of rat pituitary pars intermedia: inhibition by dopamine, an inhibitor of MSH secretion
Cells were dissociated from rat pituitary pars intermedia, maintained in culture, and subjected to electrophysiological study to establish an experimental procedure for cell reprograming. Expand