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Electrophysiological Recordings from Gonadotrophs

Electrophysiological Recordings from Gonadotrophs The electrophysiological properties of gonadotrophs have been studied in vitro, using the ovine adenohypophyseal pars tuberalis as a naturally enriched source of this cell type. Trypsin-dispersed pars tuberalis cells maintained in primary tissue culture had a membrane potential of -72 ± 4 mV (mean ± SEM) and an input resistance of 314 ± 38 MΩ. Spontaneous action potentials were not observed; however, a single spike could be induced by depolarizing current injection. The hypophysiotrophic peptide gonadotrophin-releasing hormone (GnRH) increased membrane voltage fluctuations, but these fluctuations (± 5–10 mV) did not induce action potentials or changes in membrane potential or resistance. Power spectra obtained from analysis of this noise indicated that the fundamental event underlying GnRH action has a mean life-time of 38.4 ± 4.5 ms. The obervations that cells incubated in recording medium secreted luteinizing hormone in response to GnRH and that the GnRH-induced increase in voltage noise was inhibited by Ca<sup>2+</sup> channel antagonists support the hypotheses (1) that gonadotrophin secretion is initiated by GnRH-induced Ca<sup>2+</sup> channel activation and (2) that action potentials are not a prerequisite for gonadotrophin release. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Neuroendocrinology Karger

Electrophysiological Recordings from Gonadotrophs

Mason, William T.; Waring, Dennis W.
Neuroendocrinology , Volume 41 (3): 11 – Jan 1, 1985
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Publisher
Karger
Copyright
© 1985 S. Karger AG, Basel
ISSN
0028-3835
eISSN
1423-0194
DOI
10.1159/000124186
Publisher site
See Article on Publisher Site

Abstract

The electrophysiological properties of gonadotrophs have been studied in vitro, using the ovine adenohypophyseal pars tuberalis as a naturally enriched source of this cell type. Trypsin-dispersed pars tuberalis cells maintained in primary tissue culture had a membrane potential of -72 ± 4 mV (mean ± SEM) and an input resistance of 314 ± 38 MΩ. Spontaneous action potentials were not observed; however, a single spike could be induced by depolarizing current injection. The hypophysiotrophic peptide gonadotrophin-releasing hormone (GnRH) increased membrane voltage fluctuations, but these fluctuations (± 5–10 mV) did not induce action potentials or changes in membrane potential or resistance. Power spectra obtained from analysis of this noise indicated that the fundamental event underlying GnRH action has a mean life-time of 38.4 ± 4.5 ms. The obervations that cells incubated in recording medium secreted luteinizing hormone in response to GnRH and that the GnRH-induced increase in voltage noise was inhibited by Ca<sup>2+</sup> channel antagonists support the hypotheses (1) that gonadotrophin secretion is initiated by GnRH-induced Ca<sup>2+</sup> channel activation and (2) that action potentials are not a prerequisite for gonadotrophin release.

Journal

Neuroendocrinology – Karger

Published: Jan 1, 1985

Keywords: Hormone secretion; Pituitary cells; Gonadotrophs; Anterior pituitary; Neuropeptides; Luteinizing hormone; Intracellular recording; Ion channels; Pars tuberalis

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