Glial cell line-derived neurotrophic factor and nerve growth factor receptor mRNAs are expressed in distinct subgroups of dorsal root ganglion neurons and are differentially regulated by peripheral axotomy in the rat

Abstract

We examined the colocalization of glial cell line-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) receptor genes in rat dorsal root ganglion (DRG) neurons, and investigated the changes of the gene expression following sciatic nerve transection using in situ hybridization histochemistry. About 60% and 35% of the lumbar DRG neurons expressed c-ret and trkA, proto-oncogenes of the functional receptors for GDNF and NGF, respectively. Of the DRG neurons, however, only 9% was positive for both genes. A marked enhancement of the gene expression for GDNF receptor α (GDNFR α), which is a component of GDNF receptor, was observed in DRG neurons after sciatic nerve transection, but the percentage of c-ret mRNA-expressing neurons was not changed. The trkA mRNA-expressing neurons were decreased in number. These findings suggest that GDNF and NGF support distinct subgroups in intact DRG neurons, and that these receptor genes are differentially regulated when a peripheral nerve is injured.