Fig. 3

Neuronal GRK2 in the spinal cord contributed to EA analgesia. A Experimental strategy for inhibiting spinal cord neuronal GRK2 expression by neuron-specific promoter Syn. B Western blot analysis of downregulated GRK2 protein expression in the spinal dorsal horn of mice 3 weeks after the virus administration. n = 8 for syn-eGFP group and syn-GRK2 shRNA group. Student’s t test was used for comparisons. *p < 0.05. C Representative images showed NeuN labeling (red) and eGFP-tagged (green) AAV-shRNA in the spinal cord. Scale bar, 100 μm. D Downregulation of neuronal GRK2 in the spinal cord inhibited the analgesic effect of EA in CFA-induced mechanical allodynia. Data are expressed as means ± SEM. n = 7 for syn-eGFP + CFA + EA group and n = 8 for syn-GRK2 shRNA + CFA + EA group. The statistical method is repeated measures ANOVA. *p < 0.05. E–H qRT-PCR showed neuron-specific downregulation of GRK2 inhibited the decrease of the mRNA expression of CD16/32, iNOS, TNF-α, IL-1β by EA. *p < 0.05. Student’s t test was used for comparisons. I–K Downregulation of neuronal GRK2 inhibited the rise of the mRNA expression of CD206, IL-10, IL-4by EA treatment. Results are normalized to GAPDH mRNA. Data are expressed as means ± SEM. *p < 0.05. Student’s t test was used for comparisons. n = 7 for syn-eGFP + CFA + EA group and syn-GRK2 shRNA + CFA + EA group