Previous experiments suggest that sleep deprivation (SD) is associated with growth hormone-releasing hormone (GHRH) release and that GHRH promotes sleep via intrahypothalamic sites of action. Binding of [His1, 125I-Tyr10, Nle27]hGHRH(1-32) amide and GHRH receptor (GHRH-R) mRNA levels were determined in the hypothalamus and pituitary of rats subjected to 8 h of SD and of undisturbed control rats. The characteristics of the hypothalamic GHRH binding sites differed from those of the pituitary. High affinity GHRH binding and GHRH-R mRNA levels decreased by 50% in the hypothalamus of SD rats, whereas there were no alterations in the pituitary. The results demonstrate that GHRH-Rs exist in the hypothalamus and they respond differently to SD than the GHRH-Rs in the pituitary. The SD-induced changes are explained by down-regulation of the hypothalamic GHRH-Rs induced by GHRH release during and after SD.
- Growth hormone-releasing hormone receptor
- Messenger RNA
- Somatotropic axis
ASJC Scopus subject areas