Pulsatile release of gonadotropin-releasing hormone (GnRH) from the rat hypothalamus in vitro: calcium and glucose dependency and inhibition by superactive GnRH analogs
[en] We have shown previously that the rat hypothalamus retains in vitro its capacity of generating pulsatile release of GnRH. The present study evaluated if pulsatile release of GnRH in vitro was influenced by metabolic conditions (calcium and glucose availability) and the possible self-regulatory role of GnRH in its pulsatile secretion. In the presence of a calcium-chelating agent (EGTA, 20 mM) or a calcium-channel blocker (D-600, 0.1 mM), the release of GnRH induced by a depolarization (veratridine, 50 μM) was markedly and reversibly decreased. In addition, frequency and amplitude of GnRH secretory pulses were significantly reduced (P<0.05). When glucose use was inhibited using 2-deoxyglucose (5.6 mM) the release of GnRH induced by veratridine and the frequency of GnRH pulses were also blunted (P<0.05). Superactive agonists of GnRH (Buserelin and D-TRP6-PRO9-N-ET, 10 nM) caused a prompt decrease of GnRH release in basal conditions and in the presence of veratridine. A significant inhibition (P<0.05) was observed using buserelin concentrations greater than 0.01 nM, whereas two GnRH analogs without biopotency (Leu8-GnRH, Des-gly10- N picolylamide GnRH, 100 nM) did not affect GnRH release. The two agonists of GnRH reduced by 43% to 66% (P<0.05) the occurrence of significant GnRH pulses. We conclude that, in vitro, the hypothalamic neuronal circuitry resulting in GnRH pulsatile secretion is dependent on calcium and glucose availability and is sensitive to an ultrashort-loop inhibitory feedback mechanism.
Disciplines :
Endocrinology, metabolism & nutrition
Author, co-author :
Bourguignon, Jean-Pierre ; Université de Liège - ULiège > Département des sciences cliniques > Département des sciences cliniques
GERARD, Arlette ; Centre Hospitalier Universitaire de Liège - CHU > Département de Pédiatrie > Service de pédiatrie
Debougnoux, Georgette
Rose, Joan
Franchimont, Paul
Language :
English
Title :
Pulsatile release of gonadotropin-releasing hormone (GnRH) from the rat hypothalamus in vitro: calcium and glucose dependency and inhibition by superactive GnRH analogs
Publication date :
1987
Journal title :
Endocrinology
ISSN :
0013-7227
eISSN :
1945-7170
Publisher :
The Endocrine Society, United States - Maryland
Volume :
121
Issue :
3
Pages :
993-999
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
FRSM - Fonds de la Recherche Scientifique Médicale [BE]
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