EFFECT OF 3 ANIMAL-MODELS OF INFLAMMATION ON NERVE-FIBERS IN THE SYNOVIUM

Objectives-Both sensory and sympathetic nerve fibres are depleted in t he synovium in rheumatoid arthritis (RA). The hypothesis that the indu ction of an inflammatory response in the synovium is capable of causin g depletion of nerve fibres was tested. Methods-To investigate this ph enomenon experimental arthritis in the rat was induced by three differ ent methods and the synovium was examined for evidence of nerve deplet ion by immuocytochemistry. Results-In a synovitis induced by latex sph eres, a mainly macrophage foreign body type reaction, no nerve depleti on was seen. In contrast both in an antigen-induced and a hydrogen per oxide-induced model of arthritis nerve fibre depletion was observed. T his appeared to affect sensory and sympathetic nerve fibres equally. N erve fibre depletion was only seen in areas of inflammatory cell infil tration indicating that a mixed lymphocyte and macrophage population o f cells may be necessary for this effect. Conclusions-An inflammatory response, containing lymphocytes and macrophages, in the synovium is c apable of the depletion of the finely myelinated and unmyelinated neur opeptide-containing nerves.