2.8.1 Cell counting
The number of immunopositive DRG neurons was determined by counting neurons that contained a nucleus and showed strong signal intensity in the cytoplasm >2.5-fold above the noise level in the same sections, as described previously (Nakamura et al., 2008). The total number of immunopositive neurons was calculated from two to three segment/level-matched DRG sections from 2-3 mice of each genotype.