Behavioral and physiological mouse assays for anxiety: a survey in nine mouse strains.

In order to find better and new treatments for anxiety in humans, a variety of paradigms are used to study anxiety-related processes in rodents. We studied mice in two different anxiety-related assays: the physiological stress-induced hyperthermia (SIH) paradigm and the behavioral light-dark exploration (LD) test. Eight inbred strains (129S6/SvEvTac, 129S1/SvImJ, A/J, BALB/cByJ, C3H/HeJ, C57BL/6J, DBA/2J, and FVB/NJ) and one outbred strain (CD1-ICR) were tested in both assays repeatedly. This study describes the first strain survey for the SIH paradigm. All strains showed an SIH response, but the magnitude of the response varied between lines. The inbred strain distribution pattern for the behavioral responses in the LD assay was not correlated with the SIH response. The lack of a significant correlation suggests that there is no genetic relation between such responses. Mice could be tested repeatedly in both assays without affecting the results. A new paradigm, in which both assays were combined, elucidated that behavioral responses were not altered by segments of the SIH paradigm. In contrast, exposure to the light-dark box instead of the home-cage showed a strain-dependent effect on the physiological response. We conclude that a combination of behavioral and physiological responses might lead to a better understanding in anxiety-related processes.