Tuesday, August 25, 2009

Partial restoration of GH responsiveness to ghrelin in Cushing’s disease after 6 months of ketoconazole treatment: comparison with GHRP-6 and GHRH

Silvia Correa-Silva, Sergio Nascif, Patricia Molica, Larissa Sá, Jose Gilberto Vieira and Ana-Maria Lengyel

S Correa-Silva, Endocrinology, Universidade Federal de São Paulo, Sao Paulo, 04039-002, Brazil
S Nascif, Endocrinology, Universidade Federal de São Paulo, Sao Paulo, Brazil
P Molica, Endocrinology, Universidade Federal de São Paulo, Endocrinology, Sao Paulo, Brazil
L Sá, Endocrinology, Universidade Federal de São Paulo, Sao Paulo, Brazil
J Vieira, Instituto Fleury, Sao Paulo, Brazil
A Lengyel, Endocrinology, Universidade Federal de São Paulo, Sao Paulo, Brazil

Correspondence: Silvia Correa-Silva, Email: dra.silviaregina@terra.com.br

Objective: In Cushing’s disease (CD), GH responsiveness to several stimuli including ghrelin, GHRP-6 and GHRH is blunted. Recovery of GH secretion after remission of hypercortisolism after transphenoidal surgery, radiotherapy or adrenalectomy is controversial. There are no studies evaluating the effect of primary clinical treatment with ketoconazole on GH secretion in CD. The aim of this study is to compare ghrelin-, GHRP-6- and GHRH-induced GH release before and after ketoconazole in CD.

Design: GH responses to ghrelin, GHRP-6 and GHRH of 8 untreated patients with CD (mean age:33.8 ± 3.1y; BMI:28.5 ± 0.8kg/m2) were evaluated before and after 3 and 6 months of ketoconazole treatment, and compared to 11 controls (32.1 ± 2.5; 25.0 ± 0.8).

Methods: Serum GH was measured by an immunofluorometric assay and urinary free cortisol by liquid chromatography and tandem mass spectrometry.

Results: After ketoconazole use, mean urinary free cortisol decreased significantly (before: 222.4 ± 35.0µg/24h; 3rd.month: 61.6 ± 10.1; 6th.month: 39.1 ± 10.9). Ghrelin-induced GH secretion increased significantly after 6 months (peak before:6.8 ± 2.3µg/L; 6th.month:16.0 ± 3.6), but remained lower than that of controls (54.1 ± 11.2). GH release after GHRP-6 increased, although not significantly, while GH responsiveness to GHRH was unchanged.

Conclusions: Ghrelin-induced GH release increases significantly after 6 months of ketoconazole treatment in CD. This could suggest that a decrease in cortisol levels during this time period can partially restore glucocorticoid-induced GH suppression in CD. GH-releasing mechanisms stimulated by ghrelin/GHS could be more sensitive, as no changes in GHRH-induced GH release were observed.

 

From http://www.eje.org/cgi/content/abstract/EJE-09-0459v1