BDNF and major depressive disorder: Since the activation of cAMP response element-binding protein (CREB) is known to promote BDNF expression—and both CREB and BDNF levels are typically diminished in individuals with depression—our findings that HLTP significantly upregulated both BDNF and CREB suggest a potential antidepressant mechanism involving the restoration of neuroplasticity (Chen et al., 2001).