[Nitric oxide as a regulatory factor in sleep-wakefulness mechanisms]

Although several roles of neuronal nitric oxide (NO) have been suggested, the capacity of NO on sleep-wakefulness mechanisms is open to discussion. We examined the effects of nitric oxide synthase (NOS) inhibitors on rat sleep using a microdialysis technique. When NOS inhibitor L-NAME was administrated at the central region of diencephalon, paradoxical sleep (PS) significantly increased coinciding with decrease of wakefulness in the dose-dependent manner. The effect of L-NAME on PS was completely reversed by L-arginine. Additionally, administration of NO donor NOC 18 at the action site of L-NAME completely inhibited sleep. Our results suggest that NO could play a role in the continuation of vigilance around the midline thalamic nuclei.