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. 2014 Oct 15;34(42):14055–14068. doi: 10.1523/JNEUROSCI.1722-14.2014

Figure 6.

Figure 6.

Itch regulated by VGLUT2 is mediated by CGRP and GRPR. A, R26DTA/wt;Trpv1–Cre did not differ in the observed levels of spontaneous scratch from control littermates at the age of 7 weeks (n = 8 and 9 per genotype, respectively). B–D, Itch was induced in R26DTA/wt;Trpv1–Cre mice and controls using 48/80 and CQ. B, Intradermal injections of 48/80 did not increase the number of scratch episodes in R26DTA/wt;Trpv1–Cre, whereas control animals displayed elevated itch responses (n = 6 per genotype). C, Similarly, intradermal CQ injections resulted in an increased scratch behavior in control mice and R26DTA/wt;Trpv1–Cre mice (n = 6 per genotype). D, Vglut2f/f;Trpv1–Cre mice displayed increased levels of Cgrp mRNA in DRGs compared with control mice (n = 4 per genotype). E, Intraperitoneal injection of the CGRP antagonist BIBN4096BS resulted in decreased scratch responses in Vglut2f/f;Trpv1–Cre mice compared with the level of scratch episodes before the BIBN4096BS injection (n = 6). F, Also, intrathecal injections of BIBN4096BS resulted in decreased scratch responses in Vglut2f/f;Trpv1–Cre mice compared with the level of scratch episodes before the BIBN4096BS injection (n = 6). G, There was no significant difference in substance p mRNA levels observed between Vglut2f/f;Trpv1–Cre mice and controls (n = 4 per genotype). H, Intraperitoneal injections of the substance P antagonist Win51078 in Vglut2f/f;Trpv1–Cre mice did not result in a change in the number of scratch episodes (n = 8). I, Pharmacological blockade of the GRPR receptor by intrathecal injections of the GRPR antagonist RC3095 resulted in a significantly reduced number of scratch episodes in Vglut2f/f;Trpv1–Cre mice compared with vehicle treatment and before and after the injection (n = 6). J, Genetic removal of the Grpr gene reduced the elevated levels of itch in Vglut2f/f;Trpv1–Cre mice to levels comparable with control littermates (n = 10 per genotype). Mann–Whitney test, two-tailed (A, D, G); one-way ANOVA with Dunn's post hoc test (E, F, H–J); two-way ANOVA (B, C). *p < 0.05, **p < 0.001, ***p < 0.001. Data represent means ± SEMs. Shown are R26DTA/wt;Trpv1–Cre (gray), Vglut2f/f;Trpv1–Cre (black), and respective controls in A, E, and H (white).