title: Mature and precursor brain-derived neurotrophic factor have individual roles in the mouse olfactory bulb.
abstract: BACKGROUND
  Sensory deprivation induces dramatic morphological and neurochemical changes in the olfactory bulb (OB) that are largely restricted to glomerular and granule layer interneurons. Mitral cells, pyramidal-like neurons, are resistant to sensory-deprivation-induced changes and are associated with the precursor to brain-derived neurotrophic factor (proBDNF); here, we investigate its unknown function in the adult mouse OB.
  
  
  RESULTS
  As determined using brain-slice electrophysiology in a whole-cell configuration, brain-derived neurotrophic factor (BDNF), but not proBDNF, increased mitral cell excitability. BDNF increased mitral cell action potential firing frequency and decreased interspike interval in response to current injection. In a separate set of experiments, intranasal delivery of neurotrophic factors to awake, adult mice was performed to induce sustained interneuron neurochemical changes. ProBDNF, but not BDNF, increased activated-caspase 3 and reduced tyrosine hydroxylase immunoreactivity in OB glomerular interneurons. In a parallel set of experiments, short-term sensory deprivation produced by unilateral naris occlusion generated an identical phenotype.
  
  
  CONCLUSIONS
  Our results indicate that only mature BDNF increases mitral cell excitability whereas proBDNF remains ineffective. Our demonstration that proBDNF activates an apoptotic marker in vivo is the first for any proneurotrophin and establishes a role for proBDNF in a model of neuronal plasticity.
authors.affiliation: Department of Biological Science, The Florida State University, Tallahassee, Florida, United States of America. mast@neuro.fsu.edu
authors.forename: Thomas Gerald
authors.initials: TG
authors.lastname: Mast
authors.forename: Debra Ann
authors.initials: DA
authors.lastname: Fadool
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000281:Administration, Intranasal; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000008:administration & dosage / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D051664:Kv1.3 Potassium Channel / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009830:Olfactory Bulb / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D011489:Protein Denaturation / Q000187:drug effects; D011498:Protein Precursors / Q000008:administration & dosage / Q000494:pharmacology*; D012604:Scorpion Venoms / Q000494:pharmacology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D051664:Kv1.3 Potassium Channel; D011498:Protein Precursors; D012604:Scorpion Venoms; C426674:brain-derived neurotrophic factor precursor; C077910:margatoxin; D014446:Tyrosine 3-Monooxygenase; D053148:Caspase 3