[The hypothalamic and brain stem mechanisms in the development of arterial hypertension during aging]

Effects of stimulation of hypothalamic and brain stem nuclei on arterial blood pressure were studied in adult and old rabbits and rats. In aging, thresholds of pressor reactions due to stimulation of anterior and posterior hypothalamic areas were decreased, while thresholds of depressor reactions didn't change. Long-term stimulation of nuclei of anterior and posterior hypothalamic areas induced stable hypertension, more pronounced in old animals. In old rats, as compared to adult ones: pressor responses due to stimulation of N. tr. solitarius developed more often and thresholds of these reactions were lower; amplitude of pressor responses due to stimulation of locus coeruleus was higher; changes in ventromedial hypothalamic nuclei electrogram were induced by lower electric stimulation of locus coeruleus; pressor reactions due to intracerebroventricular norepinephrine injections developed more often; ouabain microinjections into cerebral ventricles and ventromedial hypothalamic nuclei induced higher pressor reactions. Age-related changes in hypothalamic and brain stem mechanisms of blood pressure regulation may be of importance in development of arterial hypertension in old age.