WNT5A and amyotrophic lateral sclerosis: Overall, these data suggest first that in healthy conditions, MN excitability controls BSCB integrity through astrocytes and second that in ALS, the loss of MN excitability and firing leads (possibly through the decrease in signaling driven by the Gi-coupled receptor) to the down-regulation of Wnt5a/7a in astrocytes, which in turn provokes the opening of the BSCB.