Basic research has shown that acupuncture at Quchi (LI11) upregulates the expression of tight junction proteins (zona occludens-1 [ZO-1] and claudin-5), inhibits Aquaporin 4 (AQP4)–mediated brain edema, and activates the vagus nerve pathway to release acetylcholine, enhancing endothelial cell junctions. The gene discussed is AQP4; the disease is brain edema.