P2RX7 and major depressive disorder: Meanwhile, psychosocial stress, the main environmental risk factor for depression, was linked to changes in adenosine triphosphate (ATP) mediated P2X7 receptor (P2X7R) signaling and related to neuroinflammation (Kendler et al., 1999; Iwata et al., 2013; Rohleder, 2014; Calcia et al., 2016; Nelson et al., 2017; Maydych, 2019; Ribeiro et al., 2019; Kim et al., 2020).