Effects of ghrelin, GH-releasing peptide-6 (GHRP-6) and GHRH on GH, ACTH and cortisol release in hyperthyroidism before and after treatment

Effects of ghrelin, GH-releasing peptide-6 (GHRP-6) and GHRH on GH, ACTH and cortisol release in hyperthyroidism before and after treatment

Author Molica, Patricia Autor UNIFESP Google Scholar
Nascif, Sergio Oliva Autor UNIFESP Google Scholar
Correa-Silva, Silvia Regina Autor UNIFESP Google Scholar
Paiva Cunha de Sa, Larissa Bianca Autor UNIFESP Google Scholar
Henriques Vieira, Jose Gilberto Autor UNIFESP Google Scholar
Lengyel, Ana Maria Judith Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract In thyrotoxicosis GH responses to stimuli are diminished and the hypothalamic-pituitary-adrenal axis is hyperactive. There are no data on ghrelin or GHRP-6-induced GH, ACTH and cortisol release in treated hyperthyroidism. We, therefore, evaluated these responses in 10 thyrotoxic patients before treatment and in 7 of them after treatment. GHRH-induced GH release was also studied. Peak GH (mu g/L; mean +/- A SE) values after ghrelin (22.6 +/- A 3.9), GHRP-6 (13.8 +/- A 2.3) and GHRH (4.9 +/- A 0.9) were lower in hyperthyroidism before treatment compared to controls (ghrelin: 67.6 +/- A 19.3; GHRP-6: 25.4 +/- A 2.7; GHRH: 12.2 +/- A 2.8) and did not change after 6 months of euthyroidism (ghrelin: 32.7 +/- A 4.7; GHRP-6: 15.6 +/- A 3.6; GHRH: 7.4 +/- A 2.3), although GH responses to all peptides increased in similar to 50% of the patients. in thyrotoxicosis before treatment ACTH response to ghrelin was two fold higher (107.4 +/- A 26.3) than those of controls (54.9 +/- A 10.3), although not significantly. ACTH response to GHRP-6 was similar in both groups (hyperthyroid: 44.7 +/- A 9.0; controls: 31.3 +/- A 7.9). There was a trend to a decreased ACTH response to ghrelin after 3 months of euthyroidism (35.6 +/- A 5.3; P = 0.052), but after 6 months this decrease was non-significant (50.7 +/- A 14.0). After 3 months ACTH response to GHRP-6 decreased significantly (20.4 +/- A 4.2), with no further changes. in hyperthyroidism before treatment, peak cortisol (mu g/dL) responses to ghrelin (18.2 +/- A 1.2) and GHRP-6 (15.9 +/- A 1.4) were comparable to controls (ghrelin: 16.4 +/- A 1.6; GHRP-6: 13.5 +/- A 0.9) and no changes were seen after treatment. Our results suggest that the pathways of GH release after ghrelin/GHRP-6 and GHRH are similarly affected by thyroid hormone excess and hypothalamic mechanisms of ACTH release modulated by ghrelin/GHSs may be activated in this situation.
Keywords Ghrelin
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Date 2010-12-01
Published in Pituitary. New York: Springer, v. 13, n. 4, p. 315-323, 2010.
ISSN 1386-341X (Sherpa/Romeo, impact factor)
Publisher Springer
Extent 315-323
Origin http://dx.doi.org/10.1007/s11102-010-0238-3
Access rights Closed access
Type Article
Web of Science ID WOS:000283509400005
URI http://repositorio.unifesp.br/handle/11600/33118

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