BDNF and major depressive disorder: Finally, the expression levels of BDNF, a crucial and important player in regulating the pathology of depression [52, 53], were found to decrease (p = 0.0382) and the apoptotic activity marker Bax was found to increase (p < 0.0010) in the LPS‐induced supernatant group, and UB application suppressed this abnormality (p = 0.0246 and p = 0.0440), while the expression levels of Bcl‐2 remain unchanged in these groups (Figure 8E, BDNF F (2, 19) = 5.1150, p = 0.0167; Bax: F (2, 19) = 9.9140, p = 0.0011; Bcl‐2: F (2, 19) = 1.8100, p = 0.1908).