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Figure 3. Schematic diagram. Opioid peptide-containing PMN migrate into inflamed tissue. These peptides are released and bind to opioid receptors on peripheral sensory neurons leading to analgesia. CXCL2/3 produces pain control by triggering opioid peptide release. CXCL2/3-induced opioid release requires elevation of intracellular Ca2+ through flux from the endoplasmic reticulum (ER). In addition, activation of phosphoinositol-3-kinase (PI3K) is involved. PLC, phospholipase C; IP3, inositol 1,4,5-triphosphate.
