APPLICATION OF 6-HYDROXYDOPAMINE INTO THE FATPADS SURROUNDING THE DRAINING LYMPH-NODES EXACERBATES ADJUVANT-INDUCED ARTHRITIS

Adjuvant-induced arthritis (AA) was examined in Lewis rats following l ocal injection of 6-hydroxydopamine (6-OHDA) into the fatpads of the p opliteal and inguinal lymph nodes which drain the hindlimbs (DLN). Thi s method of 6-OHDA treatment resulted in noradrenergic (NA) denervatio n of DLN, spleen, and other organs in the peritoneal cavity, while spa ring NA nerve fibers in the hindlimbs. Sympathectomy exacerbated the i nflammation and. osteopathic destruction of arthritic joints. Signific ant increases in dorsoplantar width in arthritic rats following denerv ation were observed by day 27 following immunization compared to nonde nervated arthritic animals. Radiographic evaluation on day 27 after im munization confirmed the inflammation of soft tissue and revealed dete rioration of bones of the ankle joint in both AA groups compared with the control groups; more extensive joint damage was apparent in arthri tic rats following denervation compared to nondenervated arthritic rat s. These findings suggest that the NA innervation of DLN and spleen (a nd possibly other organs of the peritoneal cavity) plays a regulatory role in the expression of AA. These data supports the hypothesis that absence of NA innervation in lymphoid organs during initiation, onset, and progression of the disease results in exacerbation of AA.