NTRK2 and major depressive disorder: JiaWen et al. [46] reported that depression- andanxiety-like behaviors significantly increased in K5.Stat3C mice, an animal model of Ps.In addition, mRNA levels of brain-derived neurotrophic factor (BDNF) and tropomyosinreceptor kinase B (TrkB) in the prefrontal cortex and the hippocampus notably decreased.The use of fluoxetine, a specific serotonin reuptake inhibitor (SSRI), not only attenuatedthe depression- and anxiety-like behaviors, but, in parallel, increased the expression ofBDNF and TrkB.