[Opiate receptors and sleep. II. Effects of micro-injection of ethyl alcohol and pentobarbital in the median thalamus, periaqueductal gray matter and nucleus of the tractus solitarius of the rabbit (author's transl)].

There is an analogy between sleep EEGs produced by microinjections of morphine in the bulbo-mesencephalo-thalamic recruiting system and EEGs seen during anesthetic-induced sleep. Many studies in the last 10 years have claimed cross-tolerance and cross-dependence between opiates and ethyl alcohol. Opiates, ethyl alcohol and pentobarbital have many common metabolic actions in the central nervous system. Like morphine, microinjections of optimal equimolar doses of ethyl alcohol and pentobarbital in the bulbo-mesencephalo-thalamic sleep-inducing system of the rabbit produce sleep EEGs with abundant fast activity, which is blocked by naloxone (2 mg/kg i.v.) or by microinjections (160 micrograms) into the same structures. However, there is neither binding nor displacement by naloxone of ethyl alcohol or pentobarbital from the opiate receptor. It is thus probable that, via an as yet unknown mechanism, ethyl alcohol and pentobarbital promote the release of endorphins or peptides, which are specific ligands of all or some opiate receptors.