LOCAL-ANESTHESIA PREVENTS ACUTE INFLAMMATORY CHANGES IN NEUROPEPTIDE MESSENGER-RNA EXPRESSION IN RAT DORSAL-ROOT GANGLIA

Sensory neuropeptides, synthesised in dorsal root ganglia (DRG), are i mplicated in neurogenic inflammation and nociception in arthritis. Adj uvant monoarthritis increases primary afferent activity and alters exp ression of neuropeptide genes in DRG We investigated the role of neura l discharge in the early changes in neuropeptide gene expression. Adju vant injection increased preprotachykinin (PPT) and calcitonin gene-re lated peptide (CGRP) messenger RNA (mRNA) after 8 h, whereas somatosta tin mRNA expression remained unchanged, in innervating L5 DRG neurons. The changes in PPT mRNA expression were prevented by concurrent local anaesthesia of the sciatic nerve. Our results suggest that electrical activity mediates, in part, the changes in DRG gene expression in res ponse to acute inflammation.