Amount of TRPV1, trkB, BDNF and CGRP expression in DRG cultures after TNF-α treatment. (A) Levels of TRPV1, trkB, BDNF and CGRP mRNA in DRG cultures (N = 3-7 per group). mRNA expression levels were assessed by real-time PCR after a 5 nM TNF-α treatment for 6 to 48 hours, and the results were normalized to 18S values. Data are expressed as mean ± SEM, presented as percentage of basal (no drug treatment) and were analyzed using one-way ANOVA followed by Tukey test. *p < 0.05, **p < 0.01, ***p < 0.001; compared to corresponding basal groups. (B-J) Photomicrographs illustrate the immunoreactivity of BDNF, trkB and CGRP in DRG cultures. The amount of protein was detected by immunofluorescent stain or the immunohistochemical ABC method after a 5 nM TNF-α treatment for either 24 or 48 hours in DRG cultures. (B, E, H) Basal protein expression (no drug treatment). (C, F, I) TNF-α treatment for 24 hours. (D, G, J) TNF-α treatment for 48 hours. Scale bars, 50 μm.