Fig. 5. Changes in the TLR2 protein expression of DPA neurons at 24 h following dental pulp injury. (Aa~Af) Representative confocal images showing TLR2-positivity (asterisks) in DPA neurons labeled with Fluoro-Gold (FG) in both the non-injured TG (Aa~Ac) and the injured TG (Ad~Af). Panels (Ab, Ac) and (Ae, Af) are the high-magnification images of the inset in panels (Aa) and (Ad), respectively. (B) Quantitative data showing a significant increase of TLR2-positive DPA neurons affected by dental pulp injury (unpaired Student t-test, *p=0.0132). (C) Cell body size distributions of TLR2-positive DPA neurons in both the non-injured (101~400 µm2, n=8; 401~700 µm2, n=5; 701~1,000 µm2, n=2; 1001~1,300 µm2, n=3; ≥1,301 µm2, n=0; a total of 78 neurons) and the injured side (101~400 µm2, n=19; 401~700 µm2, n=24; 701~1,000 µm2, n=14; 1,001~1,300 µm2, n=11; ≥1,301 µm2, n=3; a total of 114 neurons). n=3 mice. (D) Representative images showing colocalization of TLR2 and CGRP in FG-labeled DPA neurons from TRPV1-ZsGreen mice (arrowheads) in both the non-injured TG (Da~De) and the injured TG (Df~Dj). (E) A representative image showing TLR2 immunoreactivity in TLR2 KO mice. (F~G) Quantitative data showing a significant decrease of TLR2-positive DPA neurons in TLR2 KO mice (one-way ANOVA with Bonferroni post hoc test, ****p<0.0001; Non-injured (TLR2 KO, n=2 mice) vs. Non-injured (TRPV1-ZsGreen, n=4 mice): *p=0.0449, F) and significant increases of TLR2 and CGRP affected by dental pulp injury in total DPA neurons (one-way ANOVA with Bonferroni post hoc test, ****p<0.0001; For TLR2, Non-injured (TRPV1-ZsGreen) vs. Injured (TRPV1-ZsGreen): **p=0.0011; For CGRP, Non-injured vs. Injured: ***p=0.0007, F), as well as TRPV1-lineage DPA neurons (one-way ANOVA with Bonferroni post hoc test, **p=0.0081; For TLR2, Non-injured vs. Injured: *p=0.0161; For CGRP, Non-injured vs. Injured: *p=0.0228, G). Scale bars, 40 µm. Data are expressed as mean±SEM.
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