The effect of serotonin microinjections into the nuclei amygdalae on EEG and behavior in the rabbit.

In chronic experiment with rabbits the influence of 5-HT on the behaviour and bioelectric activity of different brain structures had been examined. Bilateral 5-HT microinjections mostly into the basal amygdaloid nucleus cause the increase of motor activity as well as the arousal in EEG. Agents considered to be inhibitors of central serotonin receptors (cypropheptadine, methysergide) weaken the above mentioned reactions only slightly. Atropine causes the inhibition of effects produced by 5-HT. On the ground of the results obtained it seems that the stimulation caused by injecting 5-HT into amygdaloid nucleus proceeds through the mediation of acetylcholine neurons.