BDNF and major depressive disorder: It is reported that BDNF could increase the expression of p11 in primary hippocampal culture, and the increase of p11 protein by 5-HT was attenuated in primary hippocampal culture from BDNF knockout mice.30 Furthermore, the expression of mRNA and protein of p11 in the brain of BDNF knockout mice was significantly lower than that of the wild-type mice.30 Moreover, the p11 knockout mice showed depression-like behavior in the tail suspension test and FST, and BDNF did not show an antidepressant effect in these mice.30 These findings suggest a key role of p11 in the antidepressant effect of BDNF.