[Release of biogenic amines in the brain during sleep-wakefulness cycle].

Biogenic amines, including acetylcholine, act as neurotransmitters or neuromodulators in the brain of mammals. Accumulated evidences suggest the relevance of these amines to the regulatory system of sleep-wakefulness cycle. Recent development of an in vivo, microdialysis technique has revealed the existence of circadian variation in the release of these amines from various brain regions related to the regulation of sleep-wakefulness. This review focuses on the characteristics of the release of these amines determined by the microdialysis method in rats and cats during sleep-wakefulness cycle, and speculates their roles in the mechanism underlying the control of sleep and arousal state.