Article Figures & Data
Figures
- Figure 1.
RvD2, RvE1, and RvD1 differentially regulate TRPV1 and TRPA1 currents in DRG neurons via GPCRs. A, Capsaicin (CAP; 100 nm)-induced inward currents. Note a dose-dependent inhibition of TRPV1 currents by RvD2. B, Dose–response curves showing inhibition of TRPV1 currents by RvD2 and RvE1. IC50 of TRPV1 current inhibition is calculated and indicated inside the graph. C, Inhibition of TRPV1 current by RvE1 but not RvD1. D, Mustard oil AITC (300 μm)-induced inward currents. Note a dose-dependent inhibition of TRPA1 currents by RvD2. E, Dose–response curves showing inhibition of TRPA1 currents by RvD2 and RvD1. IC50 of TRPA1 current inhibition is calculated and indicated inside the graph. F, Inhibition of TRPA1 current by RvD1 but not RvE1. G, Pretreatment of DRG cultures with PTX (0.5 μg/ml, 18 h) blocks the inhibitory effects of RvD2 (1 ng/ml) on TRPV1 current (top) and TRPA1 current (bottom). H, Intracellular perfusion of GDPβS (2.5 mm, 8 min) blocks the inhibitory effects of RvD2 (1 ng/ml) on TRPV1 current (top) and TRPA1 current (bottom). n = 5–8 neurons. All results are means ± SEM.
- Figure 2.
Intraplantar and intrathecal administration of RvD2 inhibits inflammatory pain. A, Intraplantar administration of RvD2, RvD1, RvE1, DHA, or EPA reduces capsaicin-induced (1 μg) and AITC-induced (1 μg) spontaneous pain. *p < 0.05, versus vehicle; #p < 0.05. B, C, CRG-induced heat hyperalgesia (B) and mechanical allodynia (C) in vehicle-treated and RvD2-treated (10 ng, intraplantar) mice. *p < 0.05, versus vehicle. D, Formalin-induced first- and second-phase pain in vehicle- and RvD1-treated (0.01–1 ng, i.t.) mice. *p < 0.05, versus vehicle. E, CFA-induced heat hyperalgesia on day 3 and its reduction by RvD2 posttreatment (10 ng, i.t.). *p < 0.05, versus vehicle. F, G, RvD2 (10 ng, i.t.) does not alter baseline heat sensitivity (F) and motor function (G, rota-rod test) in naive animals. n = 5–8 mice. All results are means ± SEM.
- Figure 3.
RvD2 abolishes spinal cord synaptic plasticity and reverses spinal cord LTP. A–E, sEPSCs in lamina II neurons of spinal cord slices. Aa, Traces of sEPSCs showing no effect of RvD2 on baseline sEPSCs. Ab, Traces of sEPSCs showing dose-dependent inhibition of AITC-induced enhancement of sEPSCs by RvD2 (0.1 and 1 ng/ml). B, Ratio of sEPSC frequency after treatment of capsaicin (CAP; 0.1 μm), AITC (300 μm), RvD2 (0.1 and 1 ng/ml), RvE1 (1 ng/ml), and RvD1 (10 ng/ml). *p < 0.05, versus pretreatment baseline. n = 5 ∼ 9 neurons. Note that capsaicin and AITC increase the frequency of sEPSC, which is differentially blocked by RvD2, RvE1, and RvD1. C, Traces of sEPSC in a spinal cord slice from control (a) and CFA-inflamed (1 d; b) mice showing sEPSC increase after inflammation and its inhibition by RvD2 (1 ng/ml). D, E, sEPSC frequency (D) and amplitude (E) in the control and CFA-inflamed conditions, and the actions of RvD2. *p < 0.05, compared with noninflamed control; #p < 0.05, versus CFA-inflamed control. n = 5 neurons. Cont, Control. The number of neurons recorded is indicated on the top of each column. F, Reversal of LTP of C-fiber-evoked field potentials in the dorsal horn of anesthetized mice by RvD2 (10 ng, i.t.), administered 2 h after LTP induction. *p < 0.05 (vehicle vs RvD2, two-way ANOVA, n = 5 mice). All results are means ± SEM.
Tables
- Table 1.
IC50 for inhibition of TRPV1 and TRPA1 currents by RvD2, RvD1, RvE1, and their fatty acid precursors in DRG neurons
Inhibitors Molecular weight TRPV1 IC50 (nm) TRPA1 IC50 (nm) RvE1 350.4 1.0 ± 0.1 >28.5 RvD1 376.5 >26.6 8.5 ± 0.1 RvD2 376.5 0.1 ± 0.01 2.1 ± 0.5 DHA 328.5 1200.0 ± 20.0 >304,000.0 EPA 302.5 224.0 ± 10.0 >330,578.0 TRPV1 and TRPA1 currents were induced by capsaicin (100 nm) and AITC (300 μm), respectively.
