Fig. 2: SH selectively targets the TRPA1 channel. | Communications Biology

Fig. 2: SH selectively targets the TRPA1 channel.

From: Molecular defense strategy of volatile organic compound-emitting plants (order Piperales) against herbivorous mammals

Fig. 2

a H. cordata is a perennial herbaceous plant widely recognized across Japan, Korea, China, and North-East India. b Chemical structures of houttuynin and SH. c Relative preference in WT mice for water compared with water to which crude H. cordata extract (1 mg/mL, n = 8) and SH (50 and 500 μM, n = 8 for each group) at the concentrations indicated in two-bottle taste preference tests. Data represent individual animals and mean ± SEM. Statistical analysis was performed using one-way ANOVA (F = 9.563) and Bonferroni’s post hoc test: water versus crude H. cordata extract (t = 3.699, p = 0.003); water versus 50 μM SH (t = 0.5626, p > 0.9999); water versus 500 μM SH (t = 4.342, p = 0.0007); Herba houttuyniae versus 500 μM SH (t = 0.6430, p > 0.9999). **p < 0.01, ***p < 0.001, n.s. no significant difference. d Calcium imaging of cultured trigeminal ganglion (TG) neurons exposed sequentially to 500 μM SH, 1 mM allyl isothiocyanate (AITC), 100 μM capsaicin (Cap), and 70 mM potassium chloride (KCl). SH responses were observed in AITC-positive neurons (Arrow). Scale bar, 100 μm. e Averaged intracellular Ca2+ increases in cultured mouse TG neurons following consecutive applications of 500 μM SH, 10 μM Cap, and 70 mM KCl (n = 19). f Average intracellular Ca2+ increases in cultured mouse TG neurons in response to consecutive applications of 100 μM AITC, 10 μM Cap, and 70 mM KCl (n = 11). g Percentage of AITC- or SH-sensitive neurons in Cap-positive neurons, with ratios displayed above bars. h Percentage of AITC- or SH-sensitive neurons in KCl-positive neurons, with ratios displayed above bars. i Calcium imaging of HEK293T cells expressing TRPA1 or null controls exposed sequentially to SH (500 μM), AITC (1 mM), and KCl (70 mM). Scale bar, 100 μm. j Representative calcium fluorescence signals of HEK293T cells expressing TRPA1 or null controls, based on data from 5 cells. k Whole-cell TRPA1 currents elicited by the application of 1 mM 4-A and 500 μM SH. l Whole-cell TRPA1 currents elicited by the application of different doses of SH (100, 300, 350, 400, 450, and 500 μM). m Dose-response relationships for SH fitted to the Hill equation. Half-maximal response concentration (EC50) and Hill coefficient (mean ± SEM) were 343.10 ± 12.54 μM and 1.93, respectively (n = 5).

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