AQP4 and amyotrophic lateral sclerosis: Since astrocytic terminal protrusions ensheath the wall of cerebral blood vessels to maintain the normal function of the BBB (Haj-Yasein et al., 2011), and astrocytic terminal protrusions have a large amount of AQP4 channels that participate in maintaining the integrity of the BBB, studies have attempted to elucidate the pathogenesis of ALS by focusing on AQP4 channels of astrocytes (Zou S. et al., 2019).