Running-wheel avoidance behavior in the Wistar/Kyoto spontaneously hypertensive rat

Abstract

Conditioned avoidance acquisition was studied in the Okamoto-Aoki spontaneously hypertensive 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 learning 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 acquired 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 of high blood pressure in these animals.