P2RX7 and major depressive disorder: Thus, while rapidly emerging knowledge points to the regulatory role of purinergic signalling in mood-related behaviour, stress reactivity, and their pathological alterations, with novel brain-penetrant P2RX7 antagonists (JNJ-54175446, JNJ-55308942) in phase 2 and 3 clinical trials for the treatment of depression [2,26], we still lack proper understanding of the role of variation in P2RX7 in the background of depressive-like behaviours.