BDNF and depressive disorder: Further studies will focus on the expression of BDNF and the downstream effector of PKA/CREB signaling and other signaling commonly responsible for individual differences in antidepressant responses between antidepressants and acupuncture, which in turn will elucidate the underlying mechanisms concerning the antidepressant response of acupuncture and explore new prospects of integrated medicine in the treatment of depression.