P2RX2 and early-onset autosomal dominant Alzheimer disease: With respect to the role of P2X receptors in Alzheimer’s disease, a significant increase in the mRNA of P2X1, 2, 5, 7 receptors was found following 12 h of exposure of hippocampal neurons to Aβ; after 24 h, only P2X2 remained enhanced [62].