Synchronized exocytotic bursts from gonadotropin-releasing hormone-expressing cells: dual control by intrinsic cellular pulsatility and gap junctional communication

Endocrinology
R Vazquez-MartinezL S Frawley

Abstract

Periodic secretion of GnRH from the hypothalamus is the driving force for the release of gonadotropic hormones from the pituitary, but the roles of individual neurons in the context of this pulse generator are not known. In this study we used FM1-43 to monitor the membrane turnover associated with exocytosis in single GT1-7 neurons and found an intrinsic secretory pulsatility (frequency, 1.4 +/- 0.1/h; pulse duration, 17.3 +/- 0.6 min) that, during time in culture, became progressively synchronized among neighboring cells. Voltage-gated calcium channels and gap junctional communication each played a major role in synchronized pulsatility. An L-type calcium channel inhibitor, nimodipine, abolished synchronized pulsatility. In addition, functional gap junction communication among adjacent cells was detected, but only under conditions where pulsatile synchronization was also observed, and the gap junction inhibitor octanol abolished both without affecting pulse frequency or duration. Our results, therefore, provide strong evidence that the GnRH pulse generator in GT1-7 cells arises from a single cell oscillator mechanism that is synchronized through network signaling involving voltage-gated calcium channels and gap junctions.

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Citations

Mar 20, 2013·Proceedings of the National Academy of Sciences of the United States of America·Han Kyoung ChoeKyungjin Kim
Mar 20, 2010·Endocrine Reviews·Catherine A Christian, Suzanne M Moenter
Feb 25, 2014·Frontiers in Neuroendocrinology·David J Lyons, Christian Broberger
Nov 1, 2002·General and Comparative Endocrinology·Gilles M LeclercFredric R Boockfor
Jul 3, 2010·Frontiers in Neuroendocrinology·Christine L JasoniAllan E Herbison
Dec 17, 2008·Neurochemistry International·Patricia VarjuZsolt Liposits
Jan 24, 2007·Molecular and Cellular Endocrinology·Gilles M Leclerc, Fredric R Boockfor
Jul 8, 2008·Journal of Neuroendocrinology·S B Seminara, W F Crowley
Jun 15, 2013·Journal of Neuroendocrinology·S L PetersenJ A Lopez
Aug 29, 2002·Molecular Endocrinology·Rafael Vazquez-MartinezFredric R Boockfor
Sep 28, 2006·American Journal of Physiology. Endocrinology and Metabolism·Naibedya ChattopadhyayEdward M Brown
Oct 21, 2011·Physiological Reviews·Domenico BoscoPaolo Meda
Sep 5, 2014·Journal of Neurophysiology·Zahra DargaeiNeil S Magoski
May 22, 2002·Endocrinology·Craig S NunemakerSuzanne M Moenter
Jan 8, 2004·Experimental Biology and Medicine·Michael J WollerDaryle Waechter-Brulla
Dec 13, 2005·Molecular and Cellular Endocrinology·Gilles M Leclerc, Fredric R Boockfor

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