A model of psychosocial hypertension showing reversibility and progression of cardiovascular complications.

The sequence of pathophysiological changes that can result from the stimulating effects of a sustained disturbance of the social environment was studied in ten colonies of socially deprived mice. Sixteen formerly isolated males were placed with 16 normal females in population cages consisting of seven intercommunicating boxes. Six of these socially disturbed 32-member colonies were terminated after periods of interaction ranging from 2 days to 9 months. The remaining four were terminated a month or more after the males had been returned to individual isolation. Indirect blood pressure measurements, body and heart weights, and sections of hearts and aortas were studied in the males. Following the shorter exposures, blood pressure reverted to normal in a few days. Exposure of 6 months or more were associated with unchanged body weights and sustained increases in heart weight and blood pressure readings. In addition, there was a significant development of aortic arteriosclerosis and myocardial fibrosis. These changes persisted despite prolonged return to isolation.