The Korean Journal of Physiology and Pharmacology

The Korean Society of Pharmacology (대한약리학회)
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Role of Glucocorticoids in Fasting-induced Changes in Hypothalamic and Pituitary Components of the Growth Hormone (GH)-axis

  • Kim, Eun-Hee (Department of Pharmacology and Medical Research Center for Bioreaction to ROS and Biomedical Science Institute, Kyunghee University School of Medicine) ;
  • Seo, Sang-Hee (Department of Pharmacology and Medical Research Center for Bioreaction to ROS and Biomedical Science Institute, Kyunghee University School of Medicine) ;
  • Chung, Hyun-Ju (Department of Pharmacology and Medical Research Center for Bioreaction to ROS and Biomedical Science Institute, Kyunghee University School of Medicine) ;
  • Park, Seung-Joon (Department of Pharmacology and Medical Research Center for Bioreaction to ROS and Biomedical Science Institute, Kyunghee University School of Medicine)
  • Published : 2008.10.31
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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 shamoperated controls. In shamoperated 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.

Keywords

References

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