Activation of the PD-1 pathway for Pain therapy: Venlafaxine (brand name: effexor), an antidepressant which functions as a selective serotonin-norepinephrine reuptake inhibitor, increases the expression of PD-L1, attenuates acutes and chronic pain, and suppresses mechanical and thermal hypersensitivity and inhibits nociceptive neuron excitability via up-regulation of its target gene, 25/February/2017, 10.16 pm