Fig. 6

Metformin activates AMPK and decreases HMGB1 accumulation to attenuate L-OHP-induced mechanical allodynia. A The general scheme of experiments in vitro. Mechanical thresholds (B) and body weight (C) of CIPN mice treated with metformin (50, 100 and 200 mg/kg, i.p.) (n = 8). Phosphorylation of AMPK in DRG (D), HMGB1 content (E), and MMP-9/2 activity (F) in plasma of mice treated with metformin (200 mg/kg, i.p.) (n = 3). G Immunofluorescence analysis of neuronal c-fos and CGRP expression in the spinal cord of mice treated with metformin (200 mg/kg, i.p.) (n = 3). Mice were administered with L-OHP injection (3 mg/kg, i.p., five consecutive days). Metformin (200 mg/kg, i.p., q.d) or vehicle was injected for 14 days, starting a day before the first injection of L-OHP. DRG (D), Plasma (E and F) and spinal cord (G) were collected after the final treatment of metformin for western blotting or immunofluorescence assay. The quantification of c-fos and CGRP immunofluorescence was respectively represented as the number of c-fos-positive cells and the mean fluorescence intensity of CGRP in the dorsal horn. Representative bands and a data summary (n = 4 for each group) are shown. Significant differences were revealed following one-way (D-G) or two-way (B and C) ANOVA (*p < 0.05, **p < 0.01 and ***p < 0.001 vs. Control; ^#p < 0.05, ^##p < 0.01 and ^###p < 0.001 vs. L-OHP group; Bonferroni post hoc tests)