P2RX7 and Parkinson disease: Expression of the P2X7 receptor is upregulated in the brain of PD subjects and in 6-OHDA injured rats (Durrenberger et al., 2012; Oliveira-Giacomelli et al., 2019), which agrees with the hypothesis that microglial hyperactivation and consequent neuroinflammation contribute to dopaminergic neurodegeneration.