Monoarticular antigen-induced arthritis leads to pronounced bilateral upregulation of the expression of neurokinin 1 and bradykinin 2 receptors in dorsal root ganglion neurons of rats

This study describes the upregulation of neurokinin 1 and bradykinin 2 rece ptors in dorsal root ganglion (DRG) neurons in the course of antigen-induce d arthritis (AIA) in the rat knee. In the acute phase of AIA, which was cha racterized by pronounced hyperalgesia, there was a substantial bilateral in crease in the proportion of lumbar DRG neurons that express neurokinin 1 re ceptors (activated by substance P) and bradykinin 2 receptors. In the chron ic phase the upregulation of bradykinin 2 receptors persisted on the side o f inflammation. The increase in the receptor expression is relevant for the generation of acute and chronic inflammatory pain.