RESUMO
Degenerative and regnerative changes are occurred in the dorsal root ganglion (DRG) cells after the peripheral nerve injury. This experiment aimed to study the changes of neurotrophic factors and their receptors mRNA expressions in the regenerating sensory neurons after nerve crush injury. To study the regenration process of DRG neurons, the peripheral nerve was crushed rather than transection. mRNA expression was examined by in situ hybridization with oligonucleotide probes to nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT-3), nerve growth factor receptor (NGFR), trkA, trkB and trkC. The results are as following: 1. After the peripheral nerve crush injury, the number of NGF and BDNF mRNA containing neurons are increased for 5 weeks with peak at 1 day and 3 days, respectively. NGFR mRNA containing neurons are transiently decreased during several days after the lesion but return to normal within 1 week. 2. The number of trkA and trkB mRNA containing neurons are not altered by nerve crush. 3. NT-3 and trkC mRNA containing neurons are not observed in the control and lesioned DRG. This study provides the morphological evidences of neurotrophins and their receptors mRNAs changes in the DRG neurons in response to crush nerve injury.