Diurnal variations and sleep deprivation-induced changes in rat hypothalamic GHRH and somatostatin contents

J. Gardi, F. Obál, Jidong Fang, J. Zhang, J. M. Krueger

Research output: Contribution to journalArticle

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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.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume277
Issue number5 46-5
StatePublished - Nov 1 1999

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Hypothalamic Hormones
Growth Hormone-Releasing Hormone
Sleep Deprivation
Somatostatin
Sleep
Light
Photoperiod
Eye Movements
Hypothalamus
Radioimmunoassay
Messenger RNA
Peptides

All Science Journal Classification (ASJC) codes

  • Physiology
  • Physiology (medical)

Cite this

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title = "Diurnal variations and sleep deprivation-induced changes in rat hypothalamic GHRH and somatostatin contents",
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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Diurnal variations and sleep deprivation-induced changes in rat hypothalamic GHRH and somatostatin contents. / Gardi, J.; Obál, F.; Fang, Jidong; Zhang, J.; Krueger, J. M.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 277, No. 5 46-5, 01.11.1999.

Research output: Contribution to journalArticle

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