Journal article
Diurnal variations and sleep deprivation-induced changes in rat hypothalamic GHRH and somatostatin contents
American journal of physiology. Regulatory, integrative and comparative physiology, Vol.277(5), pp.R1339-R1344
11/01/1999
Handle:
https://hdl.handle.net/2376/115416
PMID: 10564205
Abstract
Previous reports indicate that hypothalamic growth hormone-releasing hormone (GHRH) promotes sleep and is involved in sleep regulation. The aim of our experiments was to determine whether the GHRH and somatostatin contents of the rat hypothalamus have diurnal variations and whether they are altered by sleep deprivation (SD). Hypothalamic samples were collected at 10 time points during the 24-h light-dark cycle. SD started at light onset. Hypothalamic samples were obtained after 4 and 8 h of SD and after 1 and 2 h of recovery following 8 h of SD. The peptides were determined by means of radioimmunoassay. GHRH displayed significant diurnal variations with low levels in the morning (a transient rise occurred at 1 h after light onset), gradual increases in the afternoon (peak at the end of the light period and beginning of the dark period), and decreases at night. SD induced significant GHRH depletion, which persisted during recovery. The afternoon rise was delayed, and the nocturnal decline of somatostatin was more rapid than the changes in GHRH. Although the patterns of the diurnal variations in GHRH and somatostatin were similar, there was no significant correlation between them. SD did not alter somatostatin significantly. Comparisons of the present results with previously reported changes in hypothalamic GHRH mRNA suggest that periods of deep nonrapid eye movement sleep (first portion of the light period and recovery sleep after SD) are associated with intense hypothalamic GHRH release.
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Details
- Title
- Diurnal variations and sleep deprivation-induced changes in rat hypothalamic GHRH and somatostatin contents
- Creators
- J Gardi - Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164-6520F Obál - Department of Physiology, A. Szent-Györgyi Medical University, Szeged, H6720, Hungary; andJ Fang - Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164-6520J Zhang - Department of Physiology and Biophysics, University of Tennessee, Memphis, Tennessee 38163J. M Krueger - Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington 99164-6520
- Publication Details
- American journal of physiology. Regulatory, integrative and comparative physiology, Vol.277(5), pp.R1339-R1344
- Academic Unit
- Integrative Physiology and Neuroscience, Department of
- Identifiers
- 99900548118201842
- Language
- English
- Resource Type
- Journal article