Two Wistar rat lines selectively bred for anxiety-related behavior show opposite reactions in elevated plus maze and fear-sensitized acoustic startle tests

Two Wistar rat lines selectively bred for high (HAB), and low anxiety-related behavior ( LAB) on the elevated plus maze were tested for the fear-sensitized acoustic startle response. The study of male rats from the F9 generation revealed a higher anxiety level of HAB rats on the elevated plus maze. However, the LAB rats displayed a higher baseline and fear-sensitized acoustic startle response compared to HAB rats, although the two rat lines did not differ in freezing duration during the interstimulus intervals in the startle experiment ( neither before, nor after, footshocks). Counts of neurons immunoreactive for corticotropin-releasing factor and neuropeptide Y in amygdaloid nuclei did not reveal any differences between the two lines, which is in marked contrast to findings in the Roman rat lines (Yilmazer-Hanke, D. M. et al. [ 2002]). The data indicate that opposite types of anxiety/fear responses are elicited in HAB/LAB rats in the elevated plus maze and fear-sensitized startle tests. Moreover, the animals displayed a differential fear response in the startle experiment, as assessed by measuring the fear-sensitized startle response and freezing.