Growth hormone responses to GH-releasing peptide (GHRP-6) in hypothyroidism

Show simple item record Pimentel, F. R. Ramos-Dias, João Carlos [UNIFESP] Ninno, FBD Facanha, CFS Liberman, B. Lengyel, AMJ 2016-01-24T12:30:19Z 2016-01-24T12:30:19Z 1997-03-01
dc.identifier.citation Clinical Endocrinology. Hoboken: Wiley-Blackwell, v. 46, n. 3, p. 295-300, 1997.
dc.identifier.issn 0300-0664
dc.description.abstract OBJECTIVE Both spontaneous and stimulated GH secretion are reduced in patients with hypothyroidism. the mechanisms involved in these alterations are not yet fully understood, GHRP-6 is a synthetic hexapeptide that releases GH both in vivo and in vitro., Its mechanism of action is unknown, but there is evidence that this peptide acts as a functional somatostatin antagonist at pituitary level. the aim of this study was to evaluate the GH response to GHRP-6 in patients with primary hypothyroidism and in normal controls,DESIGN Patients with hypothyroidism and normal controls were randomly submitted to 3 tests with GHRH (100 mu g i.v.), GHRP-6 (1 mu g/kg i.v.) and GHRH + GHRP-6, on separate days. PATIENTS Eleven patients with primary hypothyroidism were compared with 10 control subjects,MEASUREMENTS GH, TSH and free T4 were measured by immunofluorometric assay and IGF-I by radioimmunoassay.RESULTS Hypothyroid patients had markedly lower peak GH values (mean +/- SE mu g/l) after GHRH administration (4.1 +/- 0.9) compared to control subjects (24.9 +/- 5.1). After GHRP-6 injection hypothyroid patients had a significantly higher GH release (12.6 +/- 1.9) than that obtained with GHRH, while in control subjects GH values were similar (22.1 +/- 3.6). No significant differences in peak GH responses were observed following the administration of either GHRP-6 alone (controls 22.1 +/- 3.6; patients 12.6 +/- 1.9) or in combination with GHRH (controls 77.4 +/- 15.0; patients 52.8 +/- 10.9), despite the trend to smaller responses in hypothyroid patients,CONCLUSION We have shown that patients with primary hypothyroidism have higher GH responses to GHRP-6 than to GHRH, which are markedly blunted. When GHRP-6 was associated with GHRH, a significant increase in the GH response was observed in these patients, which could suggest a role for somatostatin in this process. Our data suggest that thyroid hormones modulate GH release induced by GHRH and GHRP-6 through different mechanisms. However, additional studies are necessary to further elucidate this hypothesis. en
dc.format.extent 295-300
dc.language.iso eng
dc.publisher Wiley-Blackwell
dc.relation.ispartof Clinical Endocrinology
dc.rights Acesso restrito
dc.title Growth hormone responses to GH-releasing peptide (GHRP-6) in hypothyroidism en
dc.type Artigo
dc.contributor.institution Universidade Federal de São Paulo (UNIFESP)
dc.contributor.institution HOSP BRIGADEIRO SUS
dc.description.affiliation Universidade Federal de São Paulo, ESCOLA PAULISTA MED, DIV ENDOCRINOL, BR-04034970 São Paulo, BRAZIL
dc.description.affiliation HOSP BRIGADEIRO SUS, ENDOCRINE SERV, São Paulo, BRAZIL
dc.description.affiliationUnifesp Universidade Federal de São Paulo, ESCOLA PAULISTA MED, DIV ENDOCRINOL, BR-04034970 São Paulo, BRAZIL
dc.identifier.doi 10.1046/j.1365-2265.1997.1270942.x
dc.description.source Web of Science
dc.identifier.wos WOS:A1997WV87700009


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