Figure 2
CCL2 increases density of capsaicin-evoked inward currents by upregulating TRPV1 mRNA expression in sensory neurons. (A) The concentration–response curve for the density of capsaicin-induced inward currents was obtained from small-diameter dorsal root ganglion (DRG) neurons in the absence and presence of chemokine CC chemokine ligand 2 (CCL2; 5 nM) pretreatment. Note that CCL2 preincubation increased the density of capsaicin currents without significantly affecting the EC50 value. Holding potential (VH) = −60 mV. Each point represents the mean ± standard error (SE) value of 12 neurons. (B) Quantitative RT-PCR assays showed that pretreating cultured DRG neurons with 5 nM CCL2 for 24 to 36 hours greatly increased the mRNA level of transient receptor potential vanilloid receptor 1 (TRPV1). Each bar shows the mean ± SE value of five experiments. *P <0.01.