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


METHODS
GH responses to ghrelin, GHRP-6, and GHRH of eight untreated patients with CD (mean age: 33.8+/-3.1 years; body mass index: 28.5+/-0.8 kg/m(2)) were evaluated before and after 3 and 6 months of ketoconazole treatment, and compared with 11 controls (32.1+/-2.5; 25.0+/-0.8). Methods Serum GH was measured by an immunofluorometric assay and urinary free cortisol (UFC) by liquid chromatography and tandem mass spectrometry.


RESULTS
After ketoconazole use, mean UFC decreased significantly (before: 222.4+/-35.0 microg/24 h; third month: 61.6+/-10.1; sixth month: 39.1+/-10.9). Ghrelin-induced GH secretion increased significantly after 6 months (peak before: 6.8+/-2.3 microg/l; sixth 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.
Correa-Silva
Silvia R
SR
Division of Endocrinology, Universidade Federal de São Paulo, Rua Pedro de Toledo, 910, CEP 04039-002 São Paulo, SP, Brazil. dra.silviaregina@terra.com.br
Nascif
Sérgio O
SO
Molica
Patrícia
P
Sá
Larissa B P C
LB
Vieira
José G
JG
Lengyel
Ana-Maria J
AM
D000328:Adult; D019540:Area Under Curve; D005260:Female; D054439:Ghrelin / Q000008:administration & dosage* / Q000502:physiology; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage / Q000378:metabolism / Q000502:physiology*; D019382:Human Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000652:urine; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007654:Ketoconazole / Q000008:administration & dosage*; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage* / Q000502:physiology; D047748:Pituitary ACTH Hypersecretion / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology*; D018709:Statistics, Nonparametric; D055815:Young Adult
D054439:Ghrelin; D009842:Oligopeptides; D019382:Human Growth Hormone; C041048:growth hormone releasing hexapeptide; D007334:Insulin-Like Growth Factor I; D013007:Growth Hormone-Releasing Hormone; D007654:Ketoconazole; D006854:Hydrocortisone