Gene distribution and enrichment analysis of 18-month-old untreated OXYS rats and OXYS rats treated with SkQ1. (a) An area-proportional Venn diagram, summarizing gene identifiers in the overlap (413 genes) between untreated and SkQ1-treated OXYS rats. The analysis of gene distribution points to specific changes in the expression of 746 genes in untreated OXYS rats, 380 of which are upregulated (red arrow) and 366 downregulated (green arrow). OXYS rats treated with SkQ1 showed specific changes in the expression of 185 genes, 111 of which were upregulated (red arrow) and 74 downregulated (green arrow). DAVID cluster analysis performed on DEGs exclusively expressed in the hippocampus of (b) untreated and (c) SkQ1-treated OXYS rats identified the most statistically significant upregulated and downregulated biological processes. The significance of each gene cluster is evaluated through the enrichment score (ES). An ES >1.3 is equivalent to a nonlog scale value of 0.05. The pathway analysis by KEGG for DEGs was exclusively expressed in the hippocampus of (d) untreated and (e) SkQ1-treated OXYS rats.