Article (Scientific journals)
Role of Insulin-Like Growth Factor Binding Proteins in Limitation of Igf-I Degradation into the N-Methyl-D-Aspartate Receptor Antagonist Gpe: Evidence from Gonadotrophin-Releasing Hormone Secretion in Vitro at Two Developmental Stages
Bourguignon, Jean-Pierre; Gerard, Arlette
1999In Brain Research, 847 (2), p. 247-252
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Keywords :
Insulin-Like Growth Factor; Endopeptidases; Gonadotropin-Releasing Hormone
Abstract :
[en] We showed previously that insulin-like growth factor-I (IGF-I) could inhibit the secretion of gonadotrophin-releasing hormone (GnRH) evoked in vitro by N-methyl-D-aspartate (NMDA) or veratridine depolarization. Such an IGF-I effect appeared to be mediated by its physiological breakdown product, the N-terminal tripeptide GPE. That effect was developmentally regulated since IGF-I could inhibit GnRH secretion from hypothalamic explants of 50-day-old adult rats but not from immature 15-day-old explants. We hypothesized that the IGF-binding proteins (BPs) could limit the peptide availability to endopeptidases and account for the absent IGF-I effects at 15 days. In this paper, we show that the inhibition of GnRH secretion by 10(-10) M of IGF-I at 50 days is prevented in a dose-dependent manner by 0.3 to 3 nM of IGF-BP2 as well as IGF-BP3. The inhibition caused by 10(-10) M of GPE is not affected under similar conditions. Using explants obtained at 15 days, a significant inhibition of GnRH secretion can be obtained by 10(-10) M of IGF-I in the presence of an anti IGF-BP2 antiserum used at 1:3000 and 1:1000 concentrations. These data indicate that in the immature rat brain, the IGF-BPs could act as modulators of IGF-I degradation into its subproduct GPE, a possible endogenous antagonist at NMDA receptors.
Disciplines :
Endocrinology, metabolism & nutrition
Author, co-author :
Bourguignon, Jean-Pierre ;  Université de Liège - ULiège > Département des sciences cliniques > Pédiatrie - IFRES
Gerard, Arlette ;  Centre Hospitalier Universitaire de Liège - CHU > Pédiatrie
Language :
English
Title :
Role of Insulin-Like Growth Factor Binding Proteins in Limitation of Igf-I Degradation into the N-Methyl-D-Aspartate Receptor Antagonist Gpe: Evidence from Gonadotrophin-Releasing Hormone Secretion in Vitro at Two Developmental Stages
Publication date :
20 November 1999
Journal title :
Brain Research
ISSN :
0006-8993
eISSN :
1872-6240
Publisher :
Elsevier, Netherlands
Volume :
847
Issue :
2
Pages :
247-252
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
FRSM - Fonds de la Recherche Scientifique Médicale [BE]
ULiège - Université de Liège [BE]
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