Glia-opioids interaction and neuropathic pain

Glia activated by peripheral nerve injury, releases in the spinal cord neuroexcitatory amino acids and proinflammatory cytokines involved in the development and maintenance of the neuropathic pain. Glial activation can occur also in response to chronic opioid administration with an antianalgesic effect and a contribution to opioid tolerance. Opioid-induced glial activation occurs via toll-like receptors (TLRs) expressed by the glia and partecipating also in neuropathic pain. Opioid tolerance and neuropathic pain have some common mechanism such as the underregulation of the glutammate tranporters (GLT) in the spinal cord dorsal horn. Glial activation block and development of TRL antagonists, may represent possible terapeutic strategies for the neuropathic pain treatment.