RESUMEN
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.
Asunto(s)
Envejecimiento/fisiología , Tronco Encefálico/fisiopatología , Hipertensión/fisiopatología , Hipotálamo/fisiopatología , Envejecimiento/efectos de los fármacos , Animales , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/fisiología , Tronco Encefálico/efectos de los fármacos , Cardiotónicos/farmacología , Estimulación Eléctrica , Electrodos Implantados , Hipertensión/etiología , Hipotálamo/efectos de los fármacos , Norepinefrina/farmacología , Ouabaína/farmacología , Conejos , Ratas , Ratas Wistar , Vasoconstrictores/farmacologíaRESUMEN
In rat experiments a new model of situational chronic stress, with the use of multicomponent natural stimulating influences, has been elaborated. The study revealed two subpopulations with longer and shorter lifespan in the group of stressed rats vs. control group. The survival of stressed animals was correspondent with the changes of adaptive indices. Thus the situational chronic stress has the geropromotive or geroprotective effect which depends on the organism's adaptive capacities.