English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Although it is well known that chronic treatment with glucocorticoids inhibits somatic growth, the mechanism of action of this inhibitory effect is not completely understood. It is likely that glucocorticoids act at various levels, including pituitary, hypothalamus, and peripheral organs modulating GH synthesis, secretion, and action. In this work, we evaluated the effect of dexamethasone on hypothalamic somatostatin and GH-releasing hormone (GHRH) messenger RNA (mRNA) levels by in situ hybridization. We found a significant decrease of somatostatin mRNA content in the periventricular nucleus of the hypothalamus after 3, 8, and 15 days of treatment with dexamethasone. Furthermore, we observed a reduction in GHRH mRNA levels in the arcuate nucleus after 8 and 15 days of treatment with this steroid. As it has been shown that GH feeds back to regulate somatostatin and GHRH expression at the hypothalamic level through high affinity GH receptors, we evaluated the possibility of a GH-mediated action in the inhibitory effect of glucocorticoids on somatostatin and GHRH mRNA levels. To address this issue, we first studied the GH receptor mRNA content in both the periventricular and arcuate nuclei of the hypothalamus after dexamethasone treatment. Secondly, the effect of dexamethasone on somatostatin and GHRH mRNA levels in hypophysectomized animals also was assessed. We found a significant decrease in GH receptor mRNA levels in the periventricular nucleus and in the arcuate nucleus after 1, 3, 8, and 15 days of glucocorticoid administration. Finally, in hypophysectomized rats, dexamethasone treatment for 15 days did not reduce somatostatin mRNA levels in the periventricular nucleus but significantly decreased GHRH mRNA content in the arcuate nucleus. In summary, our results suggest an inhibitory GH-mediated effect of dexamethasone on somatostatin mRNA levels in the periventricular nucleus and an inhibitory direct effect of dexamethasone on GHRH neurones in the arcuate nucleus.

Regulation of hypothalamic somatostatin, growth hormone-releasing hormone, and growth hormone receptor messenger ribonucleic acid by glucocorticoids.