EXPRESSION OF MESSENGER-RNA FOR BRAIN-DERIVED NEUROTROPHIC FACTOR IN THE DORSAL-ROOT GANGLION FOLLOWING PERIPHERAL INFLAMMATION

It is well known that the nerve growth factor (NGF) may serve as a lin k between inflammation and hyperalgesia. Recent experiments showed tha t systemic injection of NGF dramatically stimulated the expression of brain-derived neurotrophic factor (BDNF) mRNA in the dorsal root gangl ion (DRG). In the present study, we evaluated the change of BDNF mRNA in the DRG following peripheral inflammation and also observed colocal ization of BDNF and trkA mRNAs by means of in situ hybridization histo chemistry in rats. Peripheral tissue inflammation produced by an intra plantar injection of Freund's adjuvant into the paws significantly inc reased BDNF mRNA levels in the DRG and many neurons expressing trkA mR NA showed increased expession of BDNF mRNA. Intraplantar injection of antibody to NGF together with Freund's adjuvant prevented the increase in BDNF mRNA. These findings suggest that peripheral inflammation ind uces an increased expression of BDNF mRNA which is mediated by NGF in DRG. (C) 1997 Elsevier Science B.V.