Preventive carnosine supplementation attenuates painful diabetic neuropathy via restoring mitochondrial function and suppressing inflammasome activation

Figure 2 Dorsal root ganglia metabolomic profiling and correlation analyses between carnosine levels and behavioral pain indices, including paw withdrawal threshold and paw withdrawal latency. A: Principal component analysis; green represents quality control, blue indicates the control group, and yellow represents painful diabetic neuropathy; B: Partial least squares discriminant analysis; green represents quality control, blue indicates the control group, and yellow represents painful diabetic neuropathy; C: Volcano plot of differential metabolites; orange indicates upregulated differential metabolites, blue indicates downregulated differential metabolites, and gray indicates metabolites detected but not significantly different; D: Kyoto Encyclopedia of Genes and Genomes topological analysis, the color gradient represents the significance of pathways arranged by P value (Y-axis, darker red indicates smaller P values), while the size of circles represents pathway impact values (X-axis, larger circles indicate higher pathway impact value scores); pathway enrichment was analyzed using a hypergeometric test, and P values were adjusted for multiple comparisons using the Benjamini-Hochberg method to control the false discovery rate (corrected P < 0.05); E and F: Correlation analysis between carnosine levels and behavioral pain indices, including paw withdrawal threshold and paw withdrawal latency. n = 5 animals per group. QC: Quality control; PDN: Painful diabetic neuropathy; KEGG: Kyoto Encyclopedia of Genes and Genomes.