Fig. 2

De novo expression of NPY in the trigeminal ganglia, skin and mental nerve 2 and 6 weeks after CCI. NPY-IR cell bodies are absent from the trigeminal ganglia (TG) of sham animals (a) but are abundant 2 (b) and 6 weeks (c) after CCI. Quantification of the number of NPY-IR cell bodies per TG section is shown in d (n = 6). NPY-IR fibers are absent from the upper dermis of sham lip skin (e), but are present in this region 2 (f) and 6 weeks (g) after CCI. Dashed lines represent the border between the epidermis and upper dermis. Quantification of NPY fiber length (mm) per area of upper dermis (mm²) is shown in h (n = 5–6). Parasagittal sections of mental nerve (MN) from sham (i) and CCI animals 2 (j, l) and 6 weeks (k, m) after surgery. NPY fibers are absent from the MN of sham animals (i). In CCI animals, proximal and distal ligations are identified by rectangles labelled with p and d, respectively and arrows identify the regions of the nerve proximal (j, k) and distal (l, m) to the ligations. Two weeks after CCI, NPY-IR fibers are present in the nerve proximal to the ligations (j), between the ligations (j) and distal to the ligations (l). Six weeks after CCI, NPY-IR fibers are present in the nerve proximal to the ligations (k), between the ligations (k) and distal to the ligations (m). Six week sham animals were used to show representative images and data from 2 and 6 week sham animals were pooled for quantification. Values represent mean ± SEM *p < 0.05, ** < 0.01, ***p < 0.001 by 1 way ANOVA with Dunnett’s post hoc test. Scale bars = 100 μm. TG: trigeminal ganglia, MN: mental nerve, p: proximal ligature, d: distal ligature