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Under normal conditions, the sympathetic neurotransmitter noradrenaline inhibits the pro-duction and release of pro-inlfammatory cytokines. However, after peripheral nerve and tissue injury, pro-inflammatory cytokines appear to induce the expression of the alpha1A-adreno-ceptor subtype on immune cells and perhaps also on other cells in the injured tissue. In turn, noradrenaline may act on up-regulated alpha1-adrenoceptors to increase the production of the pro-inflammatory cytokine interleukin-6. In addition, the release of inflammatory mediators and nerve growth factor from keratinocytes and other cells may augment the expression of al-pha1-adrenoceptors on peripheral nerve ifbers. Consequently, nociceptive afferents acquire an abnormal excitability to adrenergic agents, and inlfammatory processes build. These mechanisms could contribute to the development of sympathetically maintained pain in conditions such as post-herpetic neuralgia, cutaneous neuromas, amputation stump pain and complex regional pain syndrome.