Regulation of hypothalamic somatostatin and growth hormone releasing hormone mRNA levels by inhibin.
Although it is well established that inhibin plays a major role in the regulation of the hypothalamic-pituitary-gonadal axis, its influence in the regulation of other neuroendocrine functions is still poorly understood. Recent results indicate that inhibin suppresses plasma GH levels, but its site of action is yet unknown. Therefore, in the present work we investigated the effects of inhibin on somatostatin and growth hormone releasing hormone (GHRH) mRNA levels in the hypothalamus by 'in situ' hybridization. We found that inhibin administration (4, 12 and 24 h, i.c.v.) led to an increase in somatostatin mRNA levels in the periventricular nucleus, and to a decrease in GHRH mRNA content in the arcuate nucleus of the hypothalamus. These findings indicate that inhibin regulates the hypothalamic levels of somatostatin and GHRH mRNA.
Carro
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Department of Physiology, Faculty of Medicine, University of Santiago de Compostela, 15700 Santiago de Compostela, Spain.
Señarís
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RM
Mallo
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F
Diéguez
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C
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000737:chemistry / Q000502:physiology; D018076:DNA, Complementary; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics*; D006727:Hormone Antagonists / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000737:chemistry / Q000502:physiology*; D007265:Inhibins / Q000494:pharmacology*; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000737:chemistry / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016622:Silver Staining; D013004:Somatostatin / Q000235:genetics*
D018076:DNA, Complementary; D006727:Hormone Antagonists; D012333:RNA, Messenger; D013004:Somatostatin; D007265:Inhibins; D013007:Growth Hormone-Releasing Hormone