Genetic influences on the responses to psychosocial challenges in rats.

"Psychosocial stress can induce chronic hypertension in normotensive strains of rats" (Henry et al. 1993). This effect is however variable among different strains. Factor analysis of the relationships between temperamental dimensions measured in social and nonsocial settings shows that sensitivity to chronic social stress loads on a "social reactivity" factor different from spontaneous aggressive tendencies. Furthermore an "end-organ" sensitivity of the cardiovascular system also seems to be necessary to explain individual vulnerability to psychosocial stress-induced hypertension. These psychological and pathophysiological characteristics combine with situational components that are not yet fully defined. The advent of telemetry techniques to monitor heart rate and blood pressure continuously without any disturbance to the animals should facilitate the analytical approach of this complex, multifactorial condition.