Kisspeptin-10 facilitates a plasma membrane-driven calcium oscillator in gonadotropin-releasing hormone-1 neurons

Endocrinology. 2009 Mar;150(3):1400-12. doi: 10.1210/en.2008-0979. Epub 2008 Oct 23.

Abstract

Kisspeptins, the natural ligands of the G-protein-coupled receptor (GPR)-54, are the most potent stimulators of GnRH-1 secretion and as such are critical to reproductive function. However, the mechanism by which kisspeptins enhance calcium-regulated neuropeptide secretion is not clear. In the present study, we used GnRH-1 neurons maintained in mice nasal explants to examine the expression and signaling of GPR54. Under basal conditions, GnRH-1 cells exhibited spontaneous baseline oscillations in intracellular calcium concentration ([Ca(2+)](i)), which were critically dependent on the operation of voltage-gated, tetrodotoxin (TTX)-sensitive sodium channels and were not coupled to calcium release from intracellular pools. Activation of native GPR54 by kisspeptin-10 initiated [Ca(2+)](i) oscillations in quiescent GnRH-1 cells, increased the frequency of calcium spiking in oscillating cells that led to summation of individual spikes into plateau-bursting type of calcium signals in a subset of active cells. These changes predominantly reflected the stimulatory effect of GPR54 activation on the plasma membrane oscillator activity via coupling of this receptor to phospholipase C signaling pathways. Both components of this pathway, inositol 1,3,4-trisphosphate and protein kinase C, contributed to the receptor-mediated modulation of baseline [Ca(2+)](i) oscillations. TTX and 2-aminoethyl diphenylborinate together abolished agonist-induced elevation in [Ca(2+)](i) in almost all cells, whereas flufenamic acid was less effective. Together these results indicate that a plasma membrane calcium oscillator is spontaneously operative in the majority of prenatal GnRH-1 neurons and is facilitated by kisspeptin-10 through phosphatidyl inositol diphosphate hydrolysis and depolarization of neurons by activating TTX-sensitive sodium channels and nonselective cationic channels.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Calcium Signaling / drug effects*
  • Cell Membrane / drug effects*
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Embryo, Mammalian
  • Embryonic Development / drug effects
  • Embryonic Development / genetics
  • Female
  • Gene Expression Regulation, Developmental
  • Gonadotropin-Releasing Hormone / metabolism*
  • Kisspeptins
  • Mice
  • Neurons / drug effects*
  • Neurons / metabolism
  • Neurons / physiology
  • Oligopeptides / pharmacology*
  • Phosphatidylinositol Phosphates / metabolism
  • Pregnancy
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism
  • Receptors, G-Protein-Coupled / physiology
  • Receptors, Kisspeptin-1
  • Signal Transduction / genetics
  • Sodium Channel Blockers / pharmacology
  • Tetrodotoxin / pharmacology

Substances

  • KISS1 protein, human
  • Kiss1r protein, mouse
  • Kisspeptins
  • Oligopeptides
  • Phosphatidylinositol Phosphates
  • Receptors, G-Protein-Coupled
  • Receptors, Kisspeptin-1
  • Sodium Channel Blockers
  • Gonadotropin-Releasing Hormone
  • Tetrodotoxin