title: TrkB expression at the neuromuscular junction is reduced during aging.
abstract: BACKGROUND
  Full-length tyrosine kinase B (TrkB.FL) and truncated TrkB (TrkB.t1) receptors are colocalized with acetylcholine receptors (AChRs) at the neuromuscular junction. We have recently shown that reduced TrkB expression leads to age-related alterations in AChR structure, neurotransmission failure, and muscle weakness.
  
  
  METHODS
  We investigated whether TrkB expression is reduced in the soleus muscle during aging.
  
  
  RESULTS
  TrkB protein expression was decreased in senescent (24-month-old) compared with 3-12-month-old mice. Loss of TrkB expression was concurrent with age-related changes in AChR morphology. Changes in mRNA levels did not correlate with protein expression, because TrkB.FL copy number was increased in the senescent soleus. No change was seen in TrkB.t1 levels.
  
  
  CONCLUSIONS
  The results suggest that reduced TrkB expression during aging may result from reduced TrkB.FL mRNA translation or increased TrkB protein turnover. Thus, maintaining adequate TrkB signaling is a potential therapeutic tool to improve muscle function during senescence.
authors.affiliation: Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York, USA. kep7@buffalo.edu
authors.forename: Kirkwood E
authors.initials: KE
authors.lastname: Personius
authors.forename: Sara D
authors.initials: SD
authors.lastname: Parker
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D006614:Hindlimb; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D020813:Receptor, trkB / Q000235:genetics / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; D011950:Receptors, Cholinergic; D020813:Receptor, trkB