Sleep states attenuate the pressor response to central amygdala stimulation

We examined the cardiovascular response to electrical stimulation of the region of the central nucleus of the amygdala during sleep and waking states in the intact cat. Stimulation for 0.5 s produced a profound pressor response in the awake animal. This response was attenuated by quiet sleep and greatly attenuated during REM sleep. The attenuation was present even when the animal aroused from the sleep state in which the stimulus was delivered. The degree of sinus arrhythmia during the bradycardia associated with the hypertensive phase was greater during waking than during quiet sleep. We speculate that REM sleep entails a "functional dissociation" between forebrain and brain stem systems involved in cardiovascular regulation.