Changes in sleep in response to intracerebral injection of insulin-like growth factor-1 (IFG-1) in the rat.
Changes in sleep were studied during 6 hours after intracerebroventricular (ICV) administration of Insulin-like growth factor-1 (IGF-1) or the structurally related insulin. IGF-1 was injected either at dark onset (0.05 or 0.5 microgram) or 6 hours after light onset (0.05, 0.5, or 5.0 microgram). The small dose of IGF-1 consistently, albeit modestly, enhanced NREMS over the 6 hour postinjection period in both the dark and the light cycles (REMS increased only at night). The NREMS-promoting activity vanished when the dose was increased to 0.5 microgram, and 5.0 microgram IGF-1 elicited a marked and prompt suppression in NREMS. Heat-inactivated IGF-1 (0.05 microgram) did not alter sleep. On a molar base, the NREMS-promoting dose of insulin was higher than that of IGF-1. Late (hours 7-17 postinjection) enhancements in EEG slow wave activity during NREMS were observed after 5.0 microgram IGF-1. The results indicate that IGF-1 can promote NREMS and may contribute to the mediation of the effects of GH on sleep. The acute sleep-suppressive activity of the high dose of IGF-1 is attributed to an inhibition of endogenous growth hormone-releasing hormone (GHRH).
Obál
F
F
Department of Physiology, Albert Szent-Gy rgyi Medical University, Szeged 6720, Hungary.
Kapás
L
L
Bodosi
B
B
Krueger
J M
JM
D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D007276:Injections, Intraventricular; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011972:Receptor, Insulin / Q000378:metabolism*; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D012894:Sleep Stages / Q000187:drug effects / Q000502:physiology
D007328:Insulin; D007334:Insulin-Like Growth Factor I; D011972:Receptor, Insulin