CHANGES IN NEURONAL MESSENGER-RNAS INDUCED BY A LOCAL INFLAMMATORY REACTION

Injection of Corynebacterium parvum into the rat dorsal root ganglion has previously been shown to cause an inflammatory reaction dominated by macrophages and to enhance regeneration of the central axons of pri mary sensory neurons. Here, neuronal mRNAs that are modified by nerve transection were analyzed by in situ hybridization following injection of C. parvum into the dorsal root ganglion. Neuronal concentrations o f mRNAs for the growth-associated protein (GAP-43) and the immediate e arly gene c-jun were increased by a local inflammatory response just a s after axotomy. The concentration of mRNA for calcitonin gene-related peptide (CGRP) was also increased in a constant subpopulation of sens ory neurons after injection of C. parvum in contrast to its decrease f ollowing axotomy. The results are consistent with the hypothesis that some of the responses to sensory neurons to axotomy are sustained by m acrophages which accumulate within the dorsal root ganglion after nerv e injury. (C) 1995 Wiley-Liss, Inc.