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Figure 5 | Journal of Neuroinflammation

Figure 5

From: CC chemokine ligand 2 upregulates the current density and expression of TRPV1 channels and Nav1.8 sodium channels in dorsal root ganglion neurons

Figure 5

CCL2 increases the density of tetrodotoxin-resistant sodium currents in small dorsal root ganglion sensory neurons. (A) In the presence of 0.5 μM tetrodotoxin (TTX), the holding potential (VH) of small dorsal root ganglion (DRG) sensory neurons was held at −80 mV, and depolarizing steps (50 milliseconds) were applied from −50 mV to 50 mV with an increment of 10 mV. The I–V (current–voltage) curve of TTX-insensitive Na+ currents was then obtained from control or chemokine CC chemokine ligand 2 (CCL2; 5 nM)-pretreated small-diameter DRG neurons. Each point represents the mean ± standard error (SE) value of 10 neurons. (B) Traces of TTX-resistant sodium currents were evoked from a VH of −80 mV to step potentials ranging from −20 mV to 20 mV. Compared with a control small DRG sensory neuron, the magnitude of TTX-insensitive Na+ currents was greatly increased in a CCL2-pretreated small-diameter DRG neuron. (C) CCL2 pretreatment increased the density of TTX-resistant sodium currents recorded at −10 mV in a dose-dependent manner. Each point shows the mean ± SE value of eight neurons. (D) Pretreating cultured DRG neurons with 5 nM CCL2 for 24 to 36 hours significantly upregulated mRNA expression of Nav1.8 without affecting the Nav1.9 mRNA level. Each bar represents the mean ± SE value of five experiments. *P <0.01 compared with control neurons.

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