Resolvin E1 Inhibits Substance P-Induced Potentiation of TRPV1 in Primary Sensory Neurons

Figure 3

RvE1 inhibits substance P- (SP-) induced potentiation of capsaicin in nociceptive neurons via GPCRs. (a) Dose response curve of RvE1-induced inhibition of TRPV1 currents in small-sized DRG neurons of normal condition (circle, black line) and in SP-treated small-sized DRG neurons (square, gray line). Inset: IC₅₀ of TRPV1 current inhibition in normal condition and SP-treated DRG neurons, respectively. (b) RvE1 (1 nM, 5 min) completely inhibited substance P- (2 μM, 8 min) induced potentiation of capsaicin-activated currents in small-sized DRG neurons. . ((c) (A)) Intracellular perfusion of GDPβS (2.5 mM, 8 min) blocks both the enhancement and inhibitory effects of capsaicin by SP and RvE1, respectively (). ((c) (B)) Pretreatment of DRG cultures with PTX (0.5 μg/mL, 18–24 h) blocks both the enhancement and inhibitory effects of capsaicin by SP and RvE1, respectively (). (d) Summary of GDPβS and PTX blocking the inhibition of SP-induced increases in capsaicin currents and RvE1-mediated inhibition of TRPV1. (e) Current-clamp recording showing that the number of capsaicin-induced action potentials is increased by SP (2 μM, 8 min) and this increase is completely inhibited by RvE1 (1 nM, 5 min). . (f) Summary of the number of action potentials. Results are presented as the mean ± SEM. ; -test versus second capsaicin treatment with SP. ; -test versus third capsaicin treatment with RvE1.

(a)

(b)

(c)

(d)

(e)

(f)