Clinical and experimental studies show that the onset of effect of acupuncture on depression is more rapid than selective serotonin reuptake inhibitors, a class of antidepressants. Acupuncture treatment is characterized by controlling anxiety and gastrointestinal discomfort. The onset time of acupuncture treatment for various pains is a week or so, which is the same as the rapid onset time of antidepressant effect of acupuncture, and the main pathway of acupuncture analgesia is through endogenous opioid system. Opioid peptides can produce pleasure, and decrease anxiety and gastrointestinal discomfort, so opioid peptides are considered to have antidepressant effect. Accordingly, the main pathway of acupuncture analgesia — the endogenous opioid system, is considered a mechanism for rapid onset of acupuncture effects on depression.

Key words: Acupuncture, Depression, Endogenous opioid peptides