[Opiate receptors and sleep. Effects of microinjections of morphine in the median thalamus and the periaqueductal gray matter of the rabbit (author's transl)].
Microinjections of morphine in optimal doses into the medial thalamus (40 micrograms) and periaqueductal gray matter (10-20 micrograms) produce slow-wave sleep with abondant spindles, in addition to analgesia. Like analgesia, the sleep-inducing effect is blocked by naloxone (1 mg/kg i.v., 160 micrograms i.c.). One may therefore conclude that the effect is related to the agonistic action of morphine on endorphine receptors. It is thus probable that the endorphins constitute a regulatory system acting on the medullary-thalamic sleep-inducing structures which generate the sleep spindles. At higher dose levels, injections of morphine into the same structures produce behavioral agitation resembling the dissociated REM sleep described by Jouvet and which is not blocked by naloxone. The agitation might be due to an indirect action of morphine, and therefore of endorphin receptors, acting on monoaminergic structures.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D008845:Microinjections; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D011817:Rabbits; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D012890:Sleep / Q000187:drug effects*; D013788:Thalamus / Q000187:drug effects / Q000502:physiology*
D011957:Receptors, Opioid; D009270:Naloxone; D009020:Morphine
Récepteurs à opiacés et sommeil. I. Effets de micro-injections de morphine dans le thalamus médian et la substance grise centrale périaqueducale du lapin.