Growth hormone response to growth hormone-releasing peptide-2 in growth hormone-deficient Little mice
DOI:
https://doi.org/10.6061/clinics/2012(03)11Keywords:
Ghrelin, GH, GHRH-R, GHRP-2, Leptin, Little mouseAbstract
OBJECTIVE: To investigate a possible direct, growth hormone-releasing, hormone-independent action of a growth hormone secretagogue, GHRP-2, in pituitary somatotroph cells in the presence of inactive growth hormonereleasing hormone receptors. MATERIALS AND METHODS: The responses of serum growth hormone to acutely injected growth hormone-releasing P-2 in lit/litmice, which represent a model of GH deficiency arising frommutated growth hormone-releasing hormonereceptors, were compared to those observed in the heterozygous (lit/+) littermates and wild-type (+/+) C57BL/6J mice. RESULTS: After the administration of 10 mcg of growth hormone-releasing P-2 to lit/lit mice, a growth hormone release of 9.3±1.5 ng/ml was observed compared with 1.04±1.15 ng/ml in controls (p<0.001). In comparison, an intermediate growth hormone release of 34.5±9.7 ng/ml and a higher growth hormone release of 163±46 ng/ml were induced in the lit/+ mice and wild-type mice, respectively. Thus, GHRP-2 stimulated growth hormone in the lit/lit mice, and the release of growth hormone in vivo may be only partially dependent on growth hormone-releasing hormone. Additionally, the plasma leptin and ghrelin levels were evaluated in the lit/lit mice under basal and stimulated conditions. CONCLUSIONS: Here, we have demonstrated that lit/lit mice, which harbor a germline mutation in the Growth hormone-releasing hormone gene, maintain a limited but statistically significant growth hormone elevation after exogenous stimulation with GHRP-2. The present data probably reflect a direct, growth hormone-independent effect on Growth hormone S (ghrelin) stimulation in the remaining pituitary somatotrophs of little mice that is mediated by growth hormone S-R 1a.Downloads
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Published
2012-01-01
Issue
Section
Basic Researches
How to Cite
Peroni, C. N., Hayashida, C. Y., Nascimento, N., Longuini, V. C., Toledo, R. A., Bartolini, P., Bowers, C. Y., & Toledo, S. P. (2012). Growth hormone response to growth hormone-releasing peptide-2 in growth hormone-deficient Little mice. Clinics, 67(3), 265-272. https://doi.org/10.6061/clinics/2012(03)11