Performance of Heterozygous Brain-Derived Neurotrophic Factor Knockout Mice on Behavioral Analogues of Anxiety, Nociception, and Depression

Evidence suggests that brain-derived neurotrophic factor (BDNF) may be important in the pathophysiology of depression, in addition to its role as a neurotrophic factor for sensory neurons. The authors conducted a series of experiments examining the behavioral profile of BDNF heterozygous knockout and wild-type mice. The heterozygous and wild-type mice did not differ on measures of activity, exploration, or hedonic sensitivity, or in the forced swim test. When assessed in the learned helplessness paradigm, heterozygous mice were slower to escape after training than were wild-type mice (p = .02). This effect may be accounted for by the fact that these mice demonstrate a reduced sensitivity to centrally mediated pain, apparent on the hot plate and Formalin injection tests of nociception. Overall, heterozygous mice were not more likely to display anxious or depressive-like behaviors and, consequently, may not constitute a murine model of genetic vulnerability to mood and anxiety disorders.