TY - JOUR
T1 - An early reduction in GH peak amplitude in preproghrelin-deficient male mice has a minor impact on linear growth
AU - Hassouna, Rim
AU - Zizzari, Philippe
AU - Tomasetto, Catherine
AU - Veldhuis, Johannes D.
AU - Fiquet, Oriane
AU - Labarthe, Alexandra
AU - Cognet, Julie
AU - Steyn, Frederik
AU - Chen, Chen
AU - Epelbaum, Jacques
AU - Tolle, Virginie
N1 - Publisher Copyright:
© 2014 by the Endocrine Society.
PY - 2014/9/1
Y1 - 2014/9/1
N2 - Ghrelin is a gut hormone processed from the proghrelin peptide acting as the endogenous ligand of the GH secretagogue receptor 1a. The regulatory role of endogenous ghrelin on pulsatile GH secretion and linear growth had to be established. The aim of the present study was to delineate the endogenous actions of preproghrelin on peripheral and central components of the GH axis. Accordingly, the ultradian pattern of GH secretion was measured in young and old preproghrelindeficient males. Blood samples were collected by tail bleeding every 10 minutes over a period of 6 hours. Analysis of the GH pulsatile pattern by deconvolution showed that GH was secreted in an ultradian manner in all genotypes, with major secretory peaks occurring at about 3-hour intervals. In older mice, the peak number was reduced and secretion was less irregular compared with younger animals. Remarkably, in young Ghrl-/-mice, the amplitude of GH secretory bursts was significantly reduced. In older mice, however, genotype differences were less significant. Changes in GH pulsatility in young Ghrl-/-mice were associated with a tendency for reduced GH pituitary contentsandplasma IGF-I concentrations, but with only a minor impactonlinear growth. In Ghrl-/-mice, despite reduced Acyl ghrelin to des-acyl ghrelin ratio,GHsecretion was not impaired. Ghrelin deficiency was not associated with a reduction in hypothalamic GHRH content or altered response to GHRH stimulation. Therefore, reduction in GHRH production and/or sensitivity do not primarily account for the alteredGHpulsatile secretion of young Ghrl-/-mice. Instead,GHRHexpression was elevated in young but not old Ghrl-/-mice, suggesting that differential compensatory responses resulting from the absence of endogenous ghrelin is occurring according to age. These results show that endogenous ghrelin is a regulator of GH pulse amplitude in growing mice but does not significantly modulate linear growth.
AB - Ghrelin is a gut hormone processed from the proghrelin peptide acting as the endogenous ligand of the GH secretagogue receptor 1a. The regulatory role of endogenous ghrelin on pulsatile GH secretion and linear growth had to be established. The aim of the present study was to delineate the endogenous actions of preproghrelin on peripheral and central components of the GH axis. Accordingly, the ultradian pattern of GH secretion was measured in young and old preproghrelindeficient males. Blood samples were collected by tail bleeding every 10 minutes over a period of 6 hours. Analysis of the GH pulsatile pattern by deconvolution showed that GH was secreted in an ultradian manner in all genotypes, with major secretory peaks occurring at about 3-hour intervals. In older mice, the peak number was reduced and secretion was less irregular compared with younger animals. Remarkably, in young Ghrl-/-mice, the amplitude of GH secretory bursts was significantly reduced. In older mice, however, genotype differences were less significant. Changes in GH pulsatility in young Ghrl-/-mice were associated with a tendency for reduced GH pituitary contentsandplasma IGF-I concentrations, but with only a minor impactonlinear growth. In Ghrl-/-mice, despite reduced Acyl ghrelin to des-acyl ghrelin ratio,GHsecretion was not impaired. Ghrelin deficiency was not associated with a reduction in hypothalamic GHRH content or altered response to GHRH stimulation. Therefore, reduction in GHRH production and/or sensitivity do not primarily account for the alteredGHpulsatile secretion of young Ghrl-/-mice. Instead,GHRHexpression was elevated in young but not old Ghrl-/-mice, suggesting that differential compensatory responses resulting from the absence of endogenous ghrelin is occurring according to age. These results show that endogenous ghrelin is a regulator of GH pulse amplitude in growing mice but does not significantly modulate linear growth.
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U2 - 10.1210/en.2014-1126
DO - 10.1210/en.2014-1126
M3 - Article
C2 - 24949662
AN - SCOPUS:84907056061
SN - 0013-7227
VL - 155
SP - 3561
EP - 3571
JO - Endocrinology (United States)
JF - Endocrinology (United States)
IS - 9
ER -