BDNF and Parkinson disease: For instance, EA improves neuropathic pain by blocking BDNF/TrkB (tropomyosin-related kinase B) signaling pathway-mediated central sensitization (9), and acupuncture activates PI3K (phosphoinositide 3-kinases) /Akt (protein kinase B) and MEK (mitogen activated protein kinase kinase) /ERK (extracellular signal–regulated kinases) signaling pathways downstream of BDNF, thereby promoting the survival of dopaminergic neurons and improving the symptoms of Parkinson’s disease (10).