INHIBITION OF SYMPATHETIC ACTIVITY BY STIMULATION OF LIMBIC SYSTEM

Abstract

In order to investigate inhibition of vasomotor and sudomotor sympathetic activities by the stimulation of the limbic system, experiments have been conducted with fifty-five bilaterally vagotomized cats, recording blood pressureskin potential. Effects of brain stimulation upon parasympathetic and cholinergic sympathetic activities were prevented by atropinization. 1. Stimulation of the hippocampus and the fornix proper yielded depression blood pressure and inhibitory response of skin potential. The depression not caused to disappear by atropinization. 2. Stimulation of the amygdala and the lateral preoptic area produced depression of blood pressure without associating inhibitory response of skin potential. Facilitatory response of skin potential was elicited with strong stimulation. depression was not affected by intravenous administration of atropine. On the basis of these experimental results, it was suggested that the areas to inhibit the sympathetic activity in the limbic system fall into two groups as far as vasomotor and sudomotor activities are concerned, and that inhibition of the sympathetic activity is not always diffusely observed in many of the effector organs.