EARLY ENVIRONMENTAL-INFLUENCES CAN ATTENUATE THE BLOOD-PRESSURE RESPONSE TO ACUTE STRESS IN BORDERLINE HYPERTENSIVE RATS

The objective of this experiment was to test the hypothesis that early environmental influences could affect cardiovascular reactivity to ac ute stress in borderline hypertensive rats. This study utilized a cros s-fostering paradigm in which borderline hypertensive rat (BHR) pups w ere reared by their natural spontaneously hypertensive rat (SHR) mothe rs, by an adoptive SHR dam, or by an adoptive Wistar-Kyoto female. Sev eral maternal behavior measures were taken throughout weaning. Cardiov ascular responses to acute stress were measured in adult BHR offspring . SHR dams spent significantly more time engaged in arched as contrast ed with passive, nursing behaviors throughout the preweaning period Al though strain of dam had no effect on resting blood pressure or heart rate, BHR reared by WKY darns had a greatly reduced blood pressure res ponse to acute stress compared with BHR raised by either natural or ad optive SHR dams. These results suggest that the expression of cardiova scular characteristics in the BHR can be modified by early environment al influences and support the hypothesis that the expression of the hy pertensive phenotype in the BHR is dependent upon information that is conveyed both genetically and environmentally. (C) 1997 Elsevier Scien ce Inc.