Fig. 7

SAFit2 desensitizes the TRPV1 channel and reduces the CGRP secretion in primary sensory neurons. Primary sensory neurons were isolated from mice and the effect of SAFit2 on the TRPV1 channel activity was assessed in calcium imaging experiments. A, C, E Representative traces of calcium influxes in sensory neurons, which were pre-incubated with 5 µM SAFit2 (A), 1 µM ddSAFit2 (C) or 1 µM structurally unrelated FKBP inhibitors (E) for 2 min and stimulated with capsaicin (100 nM, 30 s) afterwards and KCl (50 mM) as a positive control for neuronal response at the end of each experiment. B, D, F Quantification of the treated calcium response related to the untreated calcium response. G Schematic illustration of the release of CGRP from sensory neurons after capsaicin treatment. The scheme was created with images from motifolio. H Quantification of the amount of CGRP in the supernatant of treated DRG cultures. B, D, F The data represent the mean ± SEM of 25–49 sensory neurons per group. H The data represent the mean ± SEM of n = 4–5 per group *p < 0.05, ** p 0.01, one-way ANOVA with Tukey´s post hoc test. TRPV1 transient receptor potential cation channel subfamily V member 1, CGRP calcitonin gene-related peptide, SAFit2: selective antagonist of FKBP51 by induced fit 2, cap capsaicin, KCl potassium chloride