GLIAL-CELL LINE-DERIVED NEUROTROPHIC FACTOR AND NERVE GROWTH-FACTOR RECEPTOR MESSENGER-RNAS ARE EXPRESSED IN DISTINCT SUBGROUPS OF DORSAL-ROOT GANGLION NEURONS AND ARE DIFFERENTIALLY REGULATED BY PERIPHERAL AXOTOMY IN THE RAT

We examined the colocalization of glial cell line-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) receptor genes in rat dor sal root ganglion (DRG) neurons, and investigated the changes of the g ene expression following sciatic nerve transection using in situ hybri dization histochemistry. About 60% and 35% of the lumbar DRG neurons e xpressed c-ret and trkA, proto-oncogenes of the functional receptors f or GDNF and NGF, respectively. Of the DRG neurons, however, only 9% wa s positive for both genes. A marked enhancement of the gene expression for GDNF receptor alpha (GDNFR alpha), which is a component of GDNF r eceptor, was observed in DRG neurons after sciatic nerve transection, but the percentage of c-ret mRNA-expressing neurons was not changed. T he trkA mRNA-expressing neurons were decreased in number. These findin gs suggest that GDNF and NGF support distinct subgroups in intact DRG neurons, and that these receptor genes are differentially regulated wh en a peripheral nerve is injured. (C) 1998 Elsevier Science Ireland Lt d. All rights reserved