BDNF and medical procedure: Moreover, EA (5 and 50 Hz, 1–2 mA) stimulation at the Dazhui (GV14) and GV20 acupoints can protect against memory impairment by up-regulating the expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor in the hippocampal CA3 region at 14 days after transient middle cerebral artery occlusion (MCAO) (20).