Kisspeptin-evoked calcium signals in isolated primary rat gonadotropin- releasing hormone neurones.
BACKGROUND
Kisspeptin and its cognate receptor GPR54 are the central driving forces in the hypothalamus-pituitary-gonadal axis essential for sexual maturation and reproduction. Kisspeptin/GPR54 signalling stimulates gonadotropin-releasing hormone (GnRH) neurones and induces pulsatile GnRH release. The molecular signalling pathway by which kisspeptin stimulates GnRH neurones is currently under investigation.


METHODS
Primary GnRH neurones were isolated from young adult rats and loaded with the calcium indicator Fura Red. Cytosolic calcium was measured while the cells were stimulated with kisspeptin.


RESULTS
GnRH neurones show a maintained increase of cytosolic calcium upon stimulation with 100 nM kisspeptin-10. The calcium elevation was inhibited 30% by 1 μM tetrodotoxin, a voltage-gated sodium channel blocker, and 76% by 30 μM SKF96365, an inhibitor of receptor-mediated calcium entry. Furthermore, removal of extracellular calcium completely abolished the kisspeptin-induced calcium elevation.


CONCLUSIONS
Our results suggest that the major part of the kisspeptin-evoked calcium signal is generated by an action potential-independent calcium influx, possibly through channels of the classical transient receptor potential type, with an additional influx through voltage-gated calcium channels activated by sodium action potentials.
Department of Cell and Developmental Biology, University College London, London, UK.
Heike
H
Kroll
Stephen
S
Bolsover
Judith
J
Hsu
Soo-Hyun
SH
Kim
Pierre-Marc
PM
Bouloux
D000367:Age Factors; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D018929:Cell Culture Techniques; D003600:Cytosol / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D059648:Kisspeptins; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D055647:Rats, Transgenic; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology; D025521:Tumor Suppressor Proteins / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*
D007093:Imidazoles; C106628:KISS1 protein, human; D059648:Kisspeptins; D025521:Tumor Suppressor Proteins; D049452:Green Fluorescent Proteins; D007987:Gonadotropin-Releasing Hormone; D013779:Tetrodotoxin; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole