EFFECTS OF SURGICAL DENERVATION ON SUBSTANCE-P AND CALCITONIN-GENE-RELATED PEPTIDE IN ADJUVANT ARTHRITIS

The occurrence of substance P (SP) and calcitonin gene-related peptide (CGRP) was assessed in the ankle joints and dorsal root ganglia (L2-L 6) by immunohistochemistry and radioimmunoassay (RIA) after unilateral sciatic nerve section in adjuvant arthritis. Nerve section in arthrit ic rats had no clear-cut effect on warmth, redness, and swelling of an kle joints, but significantly affected the occurrence of SP and CGRP. Immunohistochemical analysis showed an almost complete disappearance o f SP-positive fibers in the ipsilateral ankle joint in normal rats aft er axotomy, whereas in arthritic rats occasional SP-positive fibers re mained. In dorsal root ganglia, only occasional SP-positive cells coul d be detected in normal and arthritic rats after axotomy. A similar bu t somewhat less pronounced effect of axotomy was noted for neuronal CG RP-LI. RIA showed a decrease in SP in ankle joints by 45% in normal ra ts and 58% in arthritic rats; the decrease in CGRP was 41% and 47%, re spectively. In dorsal root ganglia, the decrease in SP after surgical denervation was 25% in normal rats and 54% in arthritic rats; the decr ease in CGRP was 18% and 27%, respectively. The tissue concentrations of SP and CGRP in ipsilateral ankle joints and dorsal root ganglia wer e consistently correlated in normal as well as arthritic rats. The pre sent study shows that an interruption of the nerve supply to joints ca nnot fully prevent the development of arthritis, although it significa ntly reduces the occurrence of sensory neuropeptides.