Ion Channels of Pituitary Gonadotrophs and Their Roles in Signaling and Secretion
Gonadotrophs are basophilic cells of the anterior pituitary gland specialized to secrete gonadotropins in response to elevation in intracellular calcium concentration. These cells fire action potentials (APs) spontaneously, coupled with voltage-gated calcium influx of insufficient amplitude to trigg...
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doaj-f1786f2f2ee4488cae39029dcf43e2342020-11-24T22:42:55ZengFrontiers Media S.A.Frontiers in Endocrinology1664-23922017-06-01810.3389/fendo.2017.00126273593Ion Channels of Pituitary Gonadotrophs and Their Roles in Signaling and SecretionStanko S. Stojilkovic0Ivana Bjelobaba1Hana Zemkova2Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United StatesInstitute for Biological Research “Siniša Stanković”, University of Belgrade, Belgrade, SerbiaDepartment of Cellular and Molecular Neuroendocrinology, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, CzechiaGonadotrophs are basophilic cells of the anterior pituitary gland specialized to secrete gonadotropins in response to elevation in intracellular calcium concentration. These cells fire action potentials (APs) spontaneously, coupled with voltage-gated calcium influx of insufficient amplitude to trigger gonadotropin release. The spontaneous excitability of gonadotrophs reflects the expression of voltage-gated sodium, calcium, potassium, non-selective cation-conducting, and chloride channels at their plasma membrane (PM). These cells also express the hyperpolarization-activated and cyclic nucleotide-gated cation channels at the PM, as well as GABAA, nicotinic, and purinergic P2X channels gated by γ-aminobutyric acid (GABA), acetylcholine (ACh), and ATP, respectively. Activation of these channels leads to initiation or amplification of the pacemaking activity, facilitation of calcium influx, and activation of the exocytic pathway. Gonadotrophs also express calcium-conducting channels at the endoplasmic reticulum membranes gated by inositol trisphosphate and intracellular calcium. These channels are activated potently by hypothalamic gonadotropin-releasing hormone (GnRH) and less potently by several paracrine calcium-mobilizing agonists, including pituitary adenylate cyclase-activating peptides, endothelins, ACh, vasopressin, and oxytocin. Activation of these channels causes oscillatory calcium release and a rapid gonadotropin release, accompanied with a shift from tonic firing of single APs to periodic bursting type of electrical activity, which accounts for a sustained calcium signaling and gonadotropin secretion. This review summarizes our current understanding of ion channels as signaling molecules in gonadotrophs, the role of GnRH and paracrine agonists in their gating, and the cross talk among channels.http://journal.frontiersin.org/article/10.3389/fendo.2017.00126/fullgonadotrophsgonadotropin-releasing hormonevoltage-gated channelsligand-gated channelselectrical activitycalcium signaling |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Stanko S. Stojilkovic Ivana Bjelobaba Hana Zemkova |
spellingShingle |
Stanko S. Stojilkovic Ivana Bjelobaba Hana Zemkova Ion Channels of Pituitary Gonadotrophs and Their Roles in Signaling and Secretion Frontiers in Endocrinology gonadotrophs gonadotropin-releasing hormone voltage-gated channels ligand-gated channels electrical activity calcium signaling |
author_facet |
Stanko S. Stojilkovic Ivana Bjelobaba Hana Zemkova |
author_sort |
Stanko S. Stojilkovic |
title |
Ion Channels of Pituitary Gonadotrophs and Their Roles in Signaling and Secretion |
title_short |
Ion Channels of Pituitary Gonadotrophs and Their Roles in Signaling and Secretion |
title_full |
Ion Channels of Pituitary Gonadotrophs and Their Roles in Signaling and Secretion |
title_fullStr |
Ion Channels of Pituitary Gonadotrophs and Their Roles in Signaling and Secretion |
title_full_unstemmed |
Ion Channels of Pituitary Gonadotrophs and Their Roles in Signaling and Secretion |
title_sort |
ion channels of pituitary gonadotrophs and their roles in signaling and secretion |
publisher |
Frontiers Media S.A. |
series |
Frontiers in Endocrinology |
issn |
1664-2392 |
publishDate |
2017-06-01 |
description |
Gonadotrophs are basophilic cells of the anterior pituitary gland specialized to secrete gonadotropins in response to elevation in intracellular calcium concentration. These cells fire action potentials (APs) spontaneously, coupled with voltage-gated calcium influx of insufficient amplitude to trigger gonadotropin release. The spontaneous excitability of gonadotrophs reflects the expression of voltage-gated sodium, calcium, potassium, non-selective cation-conducting, and chloride channels at their plasma membrane (PM). These cells also express the hyperpolarization-activated and cyclic nucleotide-gated cation channels at the PM, as well as GABAA, nicotinic, and purinergic P2X channels gated by γ-aminobutyric acid (GABA), acetylcholine (ACh), and ATP, respectively. Activation of these channels leads to initiation or amplification of the pacemaking activity, facilitation of calcium influx, and activation of the exocytic pathway. Gonadotrophs also express calcium-conducting channels at the endoplasmic reticulum membranes gated by inositol trisphosphate and intracellular calcium. These channels are activated potently by hypothalamic gonadotropin-releasing hormone (GnRH) and less potently by several paracrine calcium-mobilizing agonists, including pituitary adenylate cyclase-activating peptides, endothelins, ACh, vasopressin, and oxytocin. Activation of these channels causes oscillatory calcium release and a rapid gonadotropin release, accompanied with a shift from tonic firing of single APs to periodic bursting type of electrical activity, which accounts for a sustained calcium signaling and gonadotropin secretion. This review summarizes our current understanding of ion channels as signaling molecules in gonadotrophs, the role of GnRH and paracrine agonists in their gating, and the cross talk among channels. |
topic |
gonadotrophs gonadotropin-releasing hormone voltage-gated channels ligand-gated channels electrical activity calcium signaling |
url |
http://journal.frontiersin.org/article/10.3389/fendo.2017.00126/full |
work_keys_str_mv |
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