Aminobutyric acid antagonists stimulate vasopressin release from organ-cultured hypothalamo-neurohypophyseal explants

Celia D. Sladek, William Armstrong

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

γ-Aminobutyric acid (GABA) has been identified in axon terminals innervating neurons of the supraoptic nucleus and has been shown to inhibit the electrical activity of supraoptic neurons when applied iontophoretically. This study examines the effects of GABA and GABA antagonists on vasopressin (VP) release from organ-cultured explahts of the hypothalamo- neurohypophyseal system (HNS). The GABA antag1 onists bicuculline and picrotoxin stimulated VP release in a concentration-dependent manner. These observations suggest that VP release by HNS explants is tonically inhibited by GABA. Exposure of HNS explants to GABA (1O-8-10-3 M) did not consistently alter basal VP release. This was true even when penicillin, which can block GABA-activated chloride channels, was omitted from the medium. Similarly, nipecotic acid, an agent that potentiates GABA activity by inhibiting GABA uptake, did not alter basal VP release; stimulation of VP release by acetylcholine and increases in osmolality was not diminished by the addition of 10-5 M GABA. The failure of exogenous GABA to modify basal and stimulated VP release suggests that GABAergic inhibition of VP release is maximally activated by endogenously released GABA in cultured HNS explants. This is consistent with evidence for a local source of GABA in the supraoptic nucleus and suggests that one role of GABA in the regulation of VP release is that of a potent local inhibitory neurotransmitter.

Original languageEnglish (US)
Pages (from-to)1576-1580
Number of pages5
JournalEndocrinology
Volume120
Issue number4
DOIs
StatePublished - Jan 1 1987

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Aminobutyrates
gamma-Aminobutyric Acid
Vasopressins
Supraoptic Nucleus
Antidiuretic Hormone Receptor Antagonists
GABA Agents
GABA Antagonists
Neurons
Picrotoxin
Chloride Channels
Bicuculline
Presynaptic Terminals
Penicillins
Osmolar Concentration
Acetylcholine
Neurotransmitter Agents

All Science Journal Classification (ASJC) codes

  • Endocrinology

Cite this

Aminobutyric acid antagonists stimulate vasopressin release from organ-cultured hypothalamo-neurohypophyseal explants. / Sladek, Celia D.; Armstrong, William.

In: Endocrinology, Vol. 120, No. 4, 01.01.1987, p. 1576-1580.

Research output: Contribution to journalArticle

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