Fig. 2

Neuroendocrine to immune communication in pain. Following a viral or bacterial infection, immune cells (i.e. T cells, macrophages, mast cells) are activated and infiltrate the site of inflammation. This results in the release of proinflammatory cytokines such as IL-1β. IL-1β then activates spinal microglia, produces the excitation of spinal dorsal horn (SDH) neurons and via activation of the HPA axis results in the release of corticosterone. Immune cells also release a plethora of inflammatory molecules including histamine and prostaglandins which results in the sensitization of nociceptors and increased pain sensitivity