Role of Glucocorticoids in Fasting-induced Changes in Hypothalamic and Pituitary Components of the Growth Hormone (GH)-axis.
10.4196/kjpp.2008.12.5.217
- Author:
Eunhee KIM
1
;
Sanghee SEO
;
Hyunju CHUNG
;
Seungjoon PARK
Author Information
1. Department of Pharmacology and Medical Research Center for Bioreaction to ROS and Biomedical Science Institute, Kyunghee University School of Medicine, Seoul, Korea. sjpark@khu.ac.kr
- Publication Type:Original Article
- Keywords:
Glucocorticoids;
Fasting;
Growth hormone-releasing hormone (GHRH);
GHRH receptor;
Growth hormone secretagogue (GHS) receptor;
Adrenalectomy
- MeSH:
Adrenalectomy;
Animals;
Corticosterone;
Fasting;
Glucocorticoids;
Growth Hormone;
Humans;
Male;
Neuropeptide Y;
Rats;
Receptors, Ghrelin;
Receptors, Neuropeptide;
Receptors, Pituitary Hormone-Regulating Hormone;
RNA, Messenger;
Salicylamides
- From:The Korean Journal of Physiology and Pharmacology
2008;12(5):217-223
- CountryRepublic of Korea
- Language:English
-
Abstract:
To directly test if elevated glucocorticoids are required for fasting-induced regulation of growth hormone (GH)-releasing hormone (GHRH), GHRH receptors (GHRH-R) and ghrelin receptors (GHS-R) expression, male rats were bilaterally adrenalectomized or sham operated. After 7 days, animals were fed ad libitum or fasted for 48 h. Bilateral adrenalectomy increased hypothalamic GHRH to 146% and decreased neuropeptide Y (NPY) mRNA to 54% of SHAM controls. Pituitary GHRH-R and GHS-R mRNA levels were decreased by adrenalectomy to 30% and 80% of sham-operated controls. In sham- operated rats, fasting suppressed hypothalamic GHRH (49%) and stimulated NPY (166%) mRNA levels, while fasting increased pituitary GHRH-R (391%) and GHS-R (218%) mRNA levels. However, in adrenalectomized rats, fasting failed to alter pituitary GHRH-R mRNA levels, while the fasting-induced suppression of GHRH and elevation of NPY and GHS-R mRNA levels remained intact. In fasted adrenalectomized rats, corticosterone replacement increased GHRH-R mRNA levels and intensified the fasting-induced decrease in GHRH, but did not alter NPY or GHS-R response. These data suggest that elevated glucocorticoids mediate the effects of fasting on hypothalamic GHRH and pituitary GHRH-R expression, while glucocorticoids are likely not the major determinant in fasting-induced increases in hypothalamic NPY and pituitary GHS-R expression.