Ghrelin and GHRP-6-induced ACTH and cortisol release in thyrotoxicosis.
Thyrotoxicosis might alter the hypothalamic-pituitary-adrenal (HPA) axis. We evaluated the effects of ghrelin and GHRP-6 on the HPA axis in 20 hyperthyroid patients and in 9 controls. Mean basal cortisol (microg/dl) and ACTH (pg/ml) levels were higher in hyperthyroidism (cortisol: 10.7 +/- 0.7; ACTH: 21.5 +/- 2.9) compared to controls (cortisol: 8.1 +/- 0.7; ACTH: 13.5 +/- 1.8). In thyrotoxicosis Delta AUC cortisol values (microg/dl.90 min) after ghrelin (484 +/- 80) and GHRP-6 (115 +/- 63) were similar to controls (ghrelin: 524 +/- 107; GHRP-6: 192 +/- 73). A significant increase in Delta AUC ACTH (pg/ml x 90 min) after ghrelin was observed in thyrotoxicosis (4,189 +/- 1,202) compared to controls (1,499 +/- 338). Delta AUC ACTH values after GHRP-6 were also higher, although not significantly (patients: 927 +/- 330; controls: 539 +/- 237). In summary, our results suggest that ghrelin-mediated pathways of ACTH release might be activated by thyroid hormone excess, but adrenocortical reserve is maintained.
Nascif
Sergio Oliva
SO
Division of Endocrinology, Federal University of São Paulo, UNIFESP/EPM, Pedro de Toledo Street, 910, São Paulo, SP, 04039-002, Brazil, snascif@uol.com.br
Molica
Patrícia
P
Correa-Silva
Silvia Regina
SR
Silva
Marcos Roberto
MR
Lengyel
Ana-Maria Judith
AM
D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000328:Adult; D005260:Female; D054439:Ghrelin / Q000494:pharmacology*; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology*; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000378:metabolism; D013971:Thyrotoxicosis / Q000378:metabolism*; D055815:Young Adult
D054439:Ghrelin; D009842:Oligopeptides; C041048:growth hormone releasing hexapeptide; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone