Journal article
Effects of systemic GHRH on sleep in intact and hypophysectomized rats
The American journal of physiology, Vol.270(2 Pt 1), pp.E230-237
02/1996
Handle:
https://hdl.handle.net/2376/109999
PMID: 8779943
Abstract
The role of pituitary growth hormone (GH) in the mediation of enhanced sleep elicited by GH-releasing hormone (GHRH) was studied in the rat. Intact and hypophysectomized (HYPOX) rats received systemic injections of GHRH or physiological saline. GHRH (0.5, 5.0, or 50 micrograms/kg in the intact rats and 0.5 or 50 micrograms/kg in HYPOX rats) was injected 6 h after light onset (P.M. injection) or just before light onset (A.M. injection, 0.5 microgram/kg in both A.M. groups). Sleep-wake activity and brain cortical temperature were recorded for 23 h (12 h light + 11 h dark). A.M. injection of GHRH did not alter sleep in normal or HYPOX rats. Each dose of P.M. GHRH increased rapid-eye-movement sleep (REMS) during 6 h postinjection in the intact rats. Hypophysectomy abolished the REMS-promoting activity of GHRH. P.M. injection of 0.5 microgram/kg GHRH increased non-REM sleep (NREMS) and enhanced electroencephalogram slow-wave activity during NREMS in both the intact and the HYPOX rats. The NREMS-promoting activity disappeared when the dose of GHRH was increased in the intact rats, whereas a tendency to enhanced NREMS was still observed after 50 micrograms/kg GHRH in the HYPOX rats. GHRH stimulated GH secretion dose dependently in the intact rats. A.M. injection of 0.5 microgram/kg GHRH tended to be less effective in stimulating GH release than the same dose administered P.M. The results confirm the time-of-day variations in the GHRH effects on sleep previously reported in human subjects. It is likely that pituitary GH is involved in the mediation of the REMS-promoting activity of GHRH but not in the NREMS-promoting activity of GHRH. Nevertheless, the results do not exclude the possibility that GH may modulate NREMS.
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Details
- Title
- Effects of systemic GHRH on sleep in intact and hypophysectomized rats
- Creators
- F Obál, Jr - Department of Physiology, A. Szent-Györgyi Medical University, Szeged, HungaryR FloydL KapásB BodosiJ M Krueger
- Publication Details
- The American journal of physiology, Vol.270(2 Pt 1), pp.E230-237
- Academic Unit
- Biomedical Sciences, Department of; Integrative Physiology and Neuroscience, Department of
- Publisher
- United States
- Grant note
- NS-27250 / NINDS NIH HHS
- Identifiers
- 99900547053401842
- Language
- English
- Resource Type
- Journal article