PDYN and depressive disorder: The effects of 100-Hz electroacupuncture may include activation of brain-derived neurotrophic factor in the ventral tegmental area, while multiple 100-Hz stimulation may have a cumulative effect related to acceleration of dynorphin synthesis and downregulation of cAMP response element-binding protein.[20] Furthermore, electroacupuncture could effectively alleviate symptoms of opioid craving and depression, and transcutaneous electrical stimulation of acupoints may help to improve symptoms of insomnia and anxiety.[21]