Decreased ghrelin-induced GH release in thyrotoxicosis: comparison with GH-releasing peptide-6 (GHRP-6) and GHRH

Decreased ghrelin-induced GH release in thyrotoxicosis: comparison with GH-releasing peptide-6 (GHRP-6) and GHRH

Author Nascif, Sergio Oliva Autor UNIFESP Google Scholar
Correa-Silva, Silvia Regina Autor UNIFESP Google Scholar
Silva, Marcos Roberto Autor UNIFESP Google Scholar
Lengyel, Ana-Maria Judith Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract In thyrotoxicosis GH response to several stimuli is impaired, but there is no data on ghrelininduced GH release in these patients. Ghrelin is a potent GH secretagogue and it also increases glucose levels in men. the aim of this study was to evaluate the effects of ghrelin (1 mu g/kg), GHRP-6 (1 mu g/kg) and GHRH (100 mu g), i.v., on GH levels in 10 hyperthyroid patients and in 8 controls. Glucose levels were also measured during ghrelin and GHRP-6 administration. in control subjects and hyperthyroid patients peak GH (mu g/l; mean +/- SE) values after ghrelin injection (controls: 66.7 +/- 13.6; hyper: 19.3 +/- 2.4) were significantly higher than those obtained after GHRP-6 (controls: 26.7 +/- 5.1; hyper: 12.6 +/- 1.3) and GHRH (controls: 13.5 +/- 4.3; hyper: 5.3 +/- 1.3). There was a significant decrease in GH responsiveness to ghrelin, GHRP-6 and GHRH in the hyperthyroid group compared to controls. in control subjects and hyperthyroid patients basal glucose (mmol/l) values were 4.5 +/- 0.1 and 4.7 +/- 0.2, respectively. There was a significant increase in glucose levels 30 min after ghrelin injection (controls: 4.9 +/- 0.1; hyper: 5.2 +/- 0.2), which remained elevated up to 120 min. When the two groups were compared no differences in glucose values were observed. GHRP-6 administration was not able to increase glucose levels in both groups. Our data shows that GH release after ghrelin, GHRP-6 and GHRH administration is decreased in thyrotoxicosis. This suggests that thyroid hormone excess interferes with GH-releasing pathways activated by these peptides. Our results also suggest that ghrelin's ability to increase glucose levels is not altered in thyrotoxicosis.
Keywords ghrelin
thyrotoxicosis
GH
GHRP-6
GHRH
Language English
Date 2007-03-01
Published in Pituitary. New York: Springer, v. 10, n. 1, p. 27-33, 2007.
ISSN 1386-341X (Sherpa/Romeo, impact factor)
Publisher Springer
Extent 27-33
Origin http://dx.doi.org/10.1007/s11102-007-0005-2
Access rights Closed access
Type Article
Web of Science ID WOS:000252215800003
URI http://repositorio.unifesp.br/handle/11600/29537

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