title: No further loss of dorsal root ganglion cells after axotomy in p75 neurotrophin receptor knockout mice.
abstract: The role of the p75 neurotrophin receptor for neuronal survival after nerve crush was studied in L5 dorsal root ganglia (DRG) of knockout mice and controls with assumption-free stereological methods. Numbers of neuronal A- and B-cells were obtained using the optical fractionator and optical disector techniques. At birth, the total number of DRG neurons was 10,000 +/- 2,600 in control mice compared with 5,100 +/- 1,300 in p75 knockout mice. During postnatal development, 1,400 neuronal B-cell bodies were lost in p75 knockouts (2P < 0.05) and 1,100 in controls (NS), whereas the A-cell population remained stable. After a sciatic nerve crush, the total neuron loss in controls was 15.4% +/- 3.5% (2P < 0.05) and 22.7% +/- 5.1% (2P < 0.05) at days 14 and 42, respectively. In contrast, there was no loss in total number of neurons after crush in p75 knockout mice. Neuronal A-cell number was unchanged after the crush in p75 knockouts as well as in controls at both times. At 14 days, the population of B-cells was reduced by 24.8% +/- 3.6% in controls and by 6.1% +/- 3.5% in p75 knockouts, this difference being significant (2P < 0.001). At 42 days, the B-cell loss was 29.6% +/- 5.5% in controls and 4.2% +/- 6.4% in p75 knockouts (2P < 0.001). In conclusion, the lack of the p75 receptor results in neuronal DRG cells that are resistant to nerve injury, pointing to a role for the receptor in apoptosis.
authors.affiliation: Department of Neurology, University Hospital of Aarhus, DK-8000 Aarhus C, Denmark. bodil@akhphd.au.dk
authors.forename: Bodil
authors.initials: B
authors.lastname: Sørensen
authors.forename: Trine
authors.initials: T
authors.lastname: Tandrup
authors.forename: Martin
authors.initials: M
authors.lastname: Koltzenburg
authors.forename: Johannes
authors.initials: J
authors.lastname: Jakobsen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D019771:Axotomy; D002452:Cell Count / Q000379:methods; D048429:Cell Size / Q000502:physiology; D005727:Ganglia, Spinal / Q000166:cytology* / Q000254:growth & development*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor / Q000172:deficiency* / Q000235:genetics; D020426:Sciatic Neuropathy
chemical_list: D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor