Figure 5.

Combined-acupoint rather than single-acupoint EA activated the endogenous cannabinoid (eCB) system. ELISA assay revealed that combined-acupoint EA but not single-acupoint EA increased the release of AEA (a) and 2-AG (b) after 6 days' EA treatment. ELISA assay demonstrated that the expression of CB₁ (c) and CB₂ (d) receptor was only upregulated in combined-acupoint EA-treated group. The western blot analysis confirmed combined-acupoint EA but not single-acupoint EA increased the expression of CB₁ (e, g) and CB₂ (f, h) in the spinal cord. Student's unpaired t-test. All data are mean ± SEM, ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗P < 0.01 vs. combined; ^#P < 0.05, ^##P < 0.01, ^###P < 0.001 vs. combined; n.s.: not significant; N = 6 in each group. CCI: chronic constriction injury; EA: electroacupuncture; AEA: anandamide; 2-AG: 2-arachidonoyl glycerol; CB₁: cannabinoid receptor 1; CB₂: cannabinoid receptor 2.