Telemetered recording of blood pressure and heart rate in different strains of rats during chronic social stress.

The role of stress in the etiology of high blood pressure and the biological mechanisms involved are still not clear. We have recently developed a paradigm of chronic social stress based on social instability and cohabitation with females, in which the different neuroendocrine responses to stress can be independently triggered. In this work, we used a telemetry technique to record blood pressure and heart rate chronically in freely moving undisturbed rats to study the influence of chronic social stress on blood pressure and heart rate in normotensive rats (Wistar and Long-Evans) and in Borderline Hypertensive Rats (BHR). No increase of blood pressure could be seen for one month of social stress in either strain. Wistar and Long-Evans rats were fully sensitive to social pressure, as shown by the changes in body weight, but may lack a specific vulnerability of the cardiovascular system. Conversely, Borderline Hypertensive rats have the genetic predisposition to develop hypertension but do not appear to be sensitive to social stimulations in the present experimental conditions. The experimental protocol used here should allow further investigation of the various possible sources of failure to induce chronic cardiovascular changes by social stress, such as blood pressure measurement techniques, social stress protocols, and genetic aspects of psychobiological and cardiovascular vulnerability to stress.