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. Author manuscript; available in PMC: 2019 Apr 30.
Published in final edited form as: Cell Rep. 2019 Mar 26;26(13):3561–3573.e4. doi: 10.1016/j.celrep.2019.02.089

Figure 4. Trpv1-Lineage Neurons Are Required in LTC4-, Serotonin-, and S1p-Evoked Itch Responses.

Figure 4.

(A–C) Intradermal injection of N-met LTC4 (0.75 μg; A), LY344864 (50 μg; B), and CYM5442 (2.23 μg; C) elicits scratching bouts that are significantly reduced in Trpv1-DTA mice compared to control littermate animals, indicating that Trpv1-lineage neurons are required for itch responses to these agents. Significant differences between genotypes were assessed by unpaired, two-tailed Student’s t test (*p = 0.0071; A, *p = 0.0116; B, *p = 0.0043; C). Data represent means ± SEM (A; n = 10 control n = 13 Trpv1-DTA mice, B; n = 7 control n = 8 Trpv1-DTA mice, C; n = 10 control n = 12 Trpv1-DTA mice). (D–F) Intradermal injection of 3 μg N-met LTC4 (D), 60 μg LY344864 (E), and 2.23 μg CYM5442 (F) evoked scratching bouts that are not significantly different between MC-DTA mice and control animals, showing that mast cells are not required for itch responses to these agents. Significant differences between genotypes were assessed by unpaired, two-tailed Student’s t test (ns [p =0.5717]; D, ns [p = 0.8224]; E, ns [p = 0.4863]; F). Data represent means ± SEM (D; n = 6 control n = 6 MC-DTA mice, E; n = 7 control, n = 7 MC-DTA mice, F; n = 6 control n = 6 MC-DTA mice).

(G–I) Representative traces of calcium responses of Trpv1-lineage neurons (Trpv1-Cre∷Ai96) to pruritogens (LY, 1 μM LY344864; LTC, 100 nM N-met LTC4; CYM, 10 μM CYM5442; HIS, 10 μM histamine; CAP, 10 μM capsaicin). Note there are broadly three classes of neurons that respond to histamine and capsaicin (G), capsaicin alone (H), and N-met LTC4, LY344864, CYM5442, hista-mine, and capsaicin (I).

(J) Raster plot of calcium responses (F/F0, see legend on the right) in 353 neurons to the indicated agents (same concentrations as in G–I). Neurons that responded to capsaicin and histamine are grouped to the left of the panel (80 neurons), capsaicin-only responsive cells are grouped in the middle of the panel (174 neurons), and those cells responding to agonists for Cysltr2, Htr1f, S1pr1, and capsaicin and histamine are grouped to the right of the panel (99 neurons).