Transient increase in cytokines and nerve growth factor in the rat dorsal root ganglia after nerve lesion and peripheral inflammation

Inflammatory response occurs, in general, at the peripheral site of injury or irritation and in the corresponding spinal dorsal horn segments. In this study, we show transient increases in the protein concentrations of interleukins 1β, 6, 8 and NGF in lumbar DRGs within hours after sciatic mononeuropathy in the rat. Comparable increases, with variation in temporal patterns, were observed after skin inflammation induced by intraplantar injection of endotoxin or complete Freund's adjuvant. The non-matching temporal profiles of cytokines and NGF increases and those of behavioral hypersensitivity, particularly peak values, suggest that the roles of these proteins are not necessarily pro-nociceptive in the DRGs at the chronic phase of neuropathy.