Running-Wheel Avoidance Behavior in the Wistar/Kyoto Spontaneously Hypertensive Rat

Okamoto-Aoki spontaneously h pertensive rat (SHR) and in the Wistar/Kyoto (WKYN) strain from which SHRs were derived. Results have demonstrated that those rats within the WKYN foundation stock exhibiting higher systolic (tail) blood pressure (BP) also exhibit greater motor activity and superior levels of discriminated active avoidance l arning in a running wheel. SHRs, and WKYNs with high BPs, acquired the CAR rapidly during the first of four sessions, taking very few pulsed shocks, whereas those WKYNs with the lowest (i.e., normotensive) BPs ~cquired the task more slowly, if at all. It is hypothesized that the increased pituitary-adrenocortical and sympatho-adrenomedullary activity previously reported for SHRs is genetically determined as an anticipatory hyperreactivity in hypertensive rats of the WKYN stock, is responsible at least in part, for the high level of running-wheel motor activity and CAR performance, and is a major contributing factor in the development ofhigh blood pressure in these animals. Active avoidance Blood pressure Pituitary-adrenocortical axis Running wheel activity Spontaneously h pertensive rat Sympathetic nervous ystem IN SUMMARIZING the findings of ten years of research concerning the pathophysiological mechanism(s)involved in the development and/or maintenance of hypertension i the spontaneously h pertensive rat (SHR), it can be state