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

Figure 4 Impact of intraperitoneal carnosine injection on mitochondrial fission and NOD-like receptor pyrin domain-containing protein 3 inflammasome activation in rats with painful diabetic neuropathy. ^cP < 0.001 vs the control group; ^dP < 0.05, ^fP < 0.001 vs the painful diabetic neuropathy (PDN) group; Linear mixed-effects models were used for the analyses in Figure 4B and D, with animal ID included as a random intercept to account for neurons nested within individual rats. Bonferroni-adjusted pairwise comparisons were performed for post hoc analyses. One-way analysis of variance followed by Tukey’s multiple comparisons test was used for Figure 4F-K. For Figure 4A-D, n = 3 rats per group. Multiple image fields and neurons were analyzed for each animal. For Figure 4E-K, n = 6 rats per group. A: Representative immunofluorescence images of dynamin-related protein 1 and neuronal marker neuronal nuclear antigen in the dorsal root ganglia (DRG) of control rats, rats with PDN, and carnosine-treated PDN rats. Scale bar = 20 μm; B: Variations in immunofluorescence intensity of dynamin-related protein 1 in DRG neurons among control, PDN, and carnosine-treated PDN rats; C: Representative immunofluorescence images of NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and neuronal marker neuronal nuclear antigen in the DRG of control, PDN, and carnosine-treated PDN rats. Scale bar = 20 μm; D: Changes in immunofluorescence intensity of NLRP3 in DRG neurons among control, PDN, and carnosine-treated PDN rats; E-K: Western blotting indicating the expression levels of proteins associated with mitochondrial fission and NLRP3 inflammasome pathway, including representative electrophoresis bands and relative expression levels. NLRP3: NOD-like receptor pyrin domain-containing protein 3; Drp1: Dynamin-related protein 1; PDN: Painful diabetic neuropathy; DAPI: 4’,6-diamidino-2-phenylindole; NeuN: Neuronal nuclear antigen; IL: Interleukin.