[Influence of cerebral and peripheral nitric oxide on sleep/wake cycle in the rat]

Through a polygraphic and pharmacological approach conducted in the rat, it is established that L-NAME (N-nitro-L-arginine methyl ester; an inhibitor of the endothelial and neuronal NO-synthases), administered intraperitoneally (i.p., 100 mg/kg) increases significantly slow wave sleep (SWS) and paradoxical sleep (PS). On the contrary, 7-NI (7-Nitro-indazole; an inhibitor of the neuronal NO-synthase), when administered locally in the nRD (n. raphe dorsalis), decreases PS without SWS changes. Finally, SIN-1 (molsidomine, a NO donor), also administered locally in the nRD (200 ng/0.2 microliter), increases PS without effects on SWS. According to the fact that L-NAME is not efficient on the cerebral NO fraction when administered i.p., it appears likely that this compound, mainly through its vascular effects, might inhibit SWS and PS. On the contrary, the effects, respectively inhibitory and facilitatory, observed on PS after nRD local injection of 7-NI and SIN-1 1 indicate that the NO-ergic component of this nucleus might facilitate PS.