Uncovering molecular elements of brain–body communication during development and treatment of neuropathic pain

Abstract

Integral to neuropathic pain is a reciprocal interaction between tumor necrosis factor-α (TNF) production and the α 2-adrenergic receptor response, offering an attractive therapeutic target. The effects of varying levels of brain TNF on α 2-adrenergic regulation of cyclic AMP (cAMP) production in the hippocampus and sciatic nerve were investigated during the development and amitriptyline treatment of chronic pain. Increased levels of TNF during the development of chronic pain transform α 2-adrenergic inhibition of cAMP production in the brain to potentiation. While α 2-adrenergic receptors regulate TNF production, they also affect descending noradrenergic pathways. Increases in levels of TNF in the brain deeply impact peripheral inflammation through regulating α 2-adrenergic receptors, offering insight into brain–body interactions during neuropathic pain. Amitriptyline as an analgesic inhibits pain-induced increases in brain-associated TNF and transforms peripheral α 2-adrenergic receptors. The dynamic equilibrium between TNF levels and α 2-adrenergic functioning is uniquely altered during development and treatment of neuropathic pain. Proper manipulations of this interaction offer efficacious treatment of neuropathic pain.