Fig. 6
CCL2 facilitates presynaptic glutamate release by acting on presynaptic CCR2. a Schematic demonstration of the experimental approach for specific expression of GCaMP6s in L3/L4 DRGs in SNS-Cre mice and Ca2+ imaging in nociceptive DRG neurons and the presynaptic spinal terminals of nociceptors. Schematic diagram showing injection of rAAV-EF1a-DIO-iGluSnFR(A184S)- WPRE-hGH-PA into the DRG of SNS-Cre mice for monitoring presynaptic glutamate release from nociceptive primary sensory neurons. b, c Typical traces (b) and heat map (c) showing that bath application of CCL2 significantly enhances the fluorescence signal intensity in the superficial layer of the spinal dorsal horn, which is blocked by the presence of RS504393. d Quantitative summary of fluorescence change. e Quantitative analysis of area under curve (AUC). f, g CCL2 significantly increases the amplitude of NMDAR-eEPSCs. h Paired-pulse ratio (PPR) before and after application of CCL2/veicle are plotted in coordinate system. i Quantification analysis showing a clear change of PPR induced by CCL2 as compared to vehicle. *P < 0.05, two-way ANOVA followed by post-hoc Bonferroni test (n = 7–22). Data are expressed as mean ± SEM