The performance of WKY rats on three tests of emotional behavior.

The behavior of Wistar, Fischer-344, and WKY male rats was observed on three tests of emotional behavior. These included the defensive-withdrawal test, the elevated plus maze, and the conditioned defensive-burying test. Rats were subsequently exposed to the water-restraint ulcerogenic procedure. Fischer-344 rats were more active in the defensive-withdrawal tests, but other behavioral measures in this test did not discriminate between the three strains. Scores reflecting anxiety in the elevated plus maze were lowest for Fischer-344 rats and highest for WKY rats, but the anxiety scores of WKY rats did not differ significantly from Wistar rats. The behavior of WKY rats was significantly different from the other two strains in the conditioned defensive burying test. While the degree of anxiety is measured by burying behavior, elicited by the novelty of prod shock, immobility was the prevalent response of WKY rats. WKY rats also revealed significantly higher ulcer severity scores when exposed to water-restraint stress after each behavioral test procedure. We propose that WKY rats are hyperresponsive to stress and that novelty stress elicits depression-like behavior, which is the prevalent behavioral stress response in WKY rats.