Figure 2.

Conditioned fear and light-dark avoidance test. (A) Cued fear memory did not generalize to a neutral tone (CS−) in response to stress experience or genotype. Social isolation increased freezing to the conditioned tone (CS+) in both genotypes, reaching statistical significance when wild type IS and CS mice were compared to VS mice. IS and CS heterozygous mice differed significantly from the ctr-group and the CS-group also differed from VS mice. In GAD65(+/+) mice all three stress protocols lead to contextual fear generalization. In contrast, only the IS-group differed from the VS-group in GAD65(+/−) mice. (B) In GAD65 wild type mice the three stress protocols lead to a gradual decrease in their activity in the light in the light-dark avoidance test, reaching significance in the CS-group. In GAD65(+/−) mice stressors that contained protracted social isolation significantly decreased activity in the light compartment compared to ctr and VS mice. The latter are indistinguishable from unstressed controls. (C) A similar pattern arose in respect to total activity, with wild type mice showing a gradual reduction with stress severity and heterozygous mice displaying a strong dependency on the stressor type. Data are mean ± s.e.m. ^*p < 0.05, ^**p < 0.01 compared to ctr of same genotype, ^#p < 0.05, ^##p < 0.01 compared to VS of the same genotype.