I. Bergmann et al., ANALYSIS OF CUTANEOUS SENSORY NEURONS IN TRANSGENIC MICE LACKING THE LOW-AFFINITY NEUROTROPHIN RECEPTOR P75, European journal of neuroscience, 9(1), 1997, pp. 18-28
Mice with a targeted mutation of the p75 low affinity neurotrophin rec
eptor display smaller peripheral nerves and dorsal root ganglia. Here
we show that transgenic mice have a significant elevation of threshold
s to noxious mechanical and heat stimuli compared with p75+/+ control
mice. Immunocytochemical analysis using antibodies against PGP 9.5 (a
panaxonal marker) and calcitonin gene related peptide (CGRP, which lab
els peptidergic neurons) showed a reduction to 73% and 54%, respective
ly, of the epidermal innervation density. However, analysis of the cel
l size distribution of toluidine blue-stained dorsal root ganglia show
ed no selective loss of neurons of particular diameters. Moreover, the
neurochemical profile of dorsal root ganglia cells as defined by trkA
, CGRP, IB4 and RT97 immunostaining revealed no significant difference
s in comparison with p75+/+ animals. Staining of the dorsal horn of th
e spinal cord for CGRP and IB4 was also normal in p75-/- animals. Taki
ng into account a previously reported loss of similar to-50% dorsal ro
ot ganglion neurons, we conclude that all types of sensory neurons are
equally depleted in p75-/- mice and that the absence of p75 impedes t
he development of more than one neuronal subtype.