Translocator Protein 18 kDa (TSPO) as a Novel Therapeutic Target for Chronic Pain

Figure 2

Molecular mechanisms by which TSPO and its ligands inhibit chronic pain induced by peripheral nerve injury. (a, b) TSPO and its ligands inhibit microglia and astrocytes to secrete inflammatory factors TNF-α, IL-1β, and IL-6. These inflammatory factors can cause neuroinflammation leading to chronic pain. (c) TSPO and its ligands inhibit CXCL1-CXCR2-dependent astrocyte-to-neuron signaling and central sensitization. (d) TSPO and its ligands inhibit the expression of the p-ERK1/2 signaling pathway and its downstream BDNF in DRG. BDNF is synthesized in DRG causing chronic pain by regulating neurotransmitter production. TNF-α: tumor necrosis factor-α; IL-1β: interleukin-1β; IL-6: interleukin-6; CXCL1: chemokine CXC motif ligand 1; CXCR2: chemokine CXC motif receptor 2; p-ERK1/2: phospho-extracellular signal-regulated kinase 1/2; BDNF: brain-derived neurotrophic factor; DRG: dorsal root ganglion.