title: Spinal cord injury-induced expression of TrkA, TrkB, phosphorylated CREB, and c-Jun in rat lumbosacral dorsal root ganglia.
abstract: Previous studies have demonstrated increased expression and phosphorylation of tyrosine kinase receptor (TrkA, TrkB) in lumbosacral DRG after chronic (6 weeks) spinal cord (T8-T10) injury. This study examined the effects of acute SCI (48 hours, 2 weeks) on TrkA and TrkB expression and phosphorylation, and CREB and c-Jun expression in DRG. A significant increase in the number of TrkA- (1.5-3-fold; P < or = 0.05), TrkB- (1.3-2.0-fold; P < or = 0.05), and phosphorylated Trk (pTrk)-immunoreactive (1.5-3-fold; P < or = 0.05) cells was observed in the L1, L6, and S1 DRG 48 hours, 2, or 6 weeks after SCI. A significant increase in the number of phosphorylated (p-) CREB-immunoreactive cells was observed in the L1, L2, L6, and S1 DRG 48 hours, 2, or 6 weeks after SCI. The largest changes in p-CREB-immunoreactivity were in L1 and L2 DRG (10-fold; P <or= 0.01) at 48 hours after SCI; however, changes were modest in bladder afferent neurons. After SCI, the overall number of c-Jun-immunoreactive cells in L1, L2, and S1 DRG was dramatically increased (3-10-fold; P < or = 0.01); however, only a low percentage of bladder afferent cells expressed c-Jun-IR before or after SCI. In summary, these results suggest that TrkA or TrkB may be involved in reorganization of micturition pathways after SCI. However, CREB or c-Jun may not be downstream transcription factors in Trk-mediated signaling cascades in micturition reflex pathways after SCI but may play a role in other, nonbladder SCI-induced changes.
authors.affiliation: Department of Neurology, University of Vermont College of Medicine, Burlington, Vermont 05405, USA.
authors.forename: Li-Ya
authors.initials: LY
authors.lastname: Qiao
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Vizzard
mesh_terms: D000208:Acute Disease; D000818:Animals; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D008161:Lumbosacral Region; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009475:Neurons, Afferent / Q000378:metabolism*; D010766:Phosphorylation; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020917:Receptor, trkA / Q000378:metabolism*; D020813:Receptor, trkB / Q000378:metabolism; D013119:Spinal Cord Injuries / Q000378:metabolism*; D001743:Urinary Bladder / Q000294:innervation; D014554:Urination / Q000502:physiology
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D016755:Proto-Oncogene Proteins c-jun; D020917:Receptor, trkA; D020813:Receptor, trkB