[Vasoactive peptides in the structure of defensive motivational excitation]

In experiments on rabbits, the action was studied of vasoactive peptides angiotensin-II, bradykinin and lysyl-vasopressin, injected into the brain ventricles, on a passive defensive reaction to electrical stimulation of the ventromedial hypothalamus. It was found that angiotensin-II and lysyl-vasopressin had a pronounced inhibitory influence, while bradykinin had a facilitatory effect on this reaction. Electrical stimulation of the ventromedial hypothalamus predominantly facilitated reactions of individual neurones of the sensorimotor cortex to angiotensin-II and bradykinin. Intraperitoneal injection of P-substance to rats in conditions of an acute conflict situation producing an emotional stress, brought about a significant diminution of sudden death incidence from cardiovascular insufficiency.