Oxidative Stress-Induced Suppression of Metabolism Pathways in Dahl Salt-Sensitive Rats

Background: We have reported that a high-salt (HS) diet enhances glycolysis as determined in normal Sprague Dawley (SD) rats by measuring the flux of kidney metabolites in rats chronically instrumented with a renal blood flow probe and renal arteriovenous catheters, which provided sequential samples for global metabolic analysis combined with tissue transcriptomic analyses (PMID: 37575482). In the present study, the kidney cortical (Cx) and outer medullary (OM) transcriptomic responses to a HS diet are reported in Dahl salt-sensitive (SS) rats compared to SSNox4-/- rats with a global knockout of NADPH oxidase 4 (NOX4) to reduce oxidative stress, and compared to salt-resistant SD rats. Methods: Male SS, SSNox4-/- and SD rats were fed either a 0.4% diet, a 4% diet for 7 days, or for 21 days (HS21). Cx and OM were removed for mRNAseq analysis (Novogene, Inc). Comparisons with previously published SD data was performed by publicly available software (RNAseqChef and DAVID). Results: 1724 mRNAs in Cx and 2775 in OM had FDR < 0.05 and fold change > 2, comparing SS and SD at HS21. Among these mRNAs, we selected those with patterns of response to salt that are unique in SS relative to SD and SSNox4-/- by divisive clustering analysis. There were 446 mRNAs in Cx and 1550 in OM that followed this pattern. Only the “Protein digestion and absorption” pathway was significant in the pathway analysis of these mRNAs in Cx. This pathway includes Slc3a1 (amino acid transporter), and Atp1A4 (Na/K ATPase) which was consistently greater in SS. Collagen mRNAs were increased only in SS with HS. The OM, in contrast, revealed 11 pathways including “carbon metabolism”, “biosynthesis of amino acid” and others. Aco1 (aconitase), Pc (pyruvate carboxylase), Pklr (pyruvate kinase) and Ass1 (argininosuccinate synthase) in these pathways were consistently low in SS. Conclusion: Transcriptomic response to HS clearly differed when comparing kidneys of SS to SSNox4-/- and SD rats. Carbon metabolism and amino acid synthesis related genes were suppressed in OM in SS which could functionally lead to lactate accumulation and eventually renal damage as energy demand increased with HS. These changes appear to be driven by increased oxidative stress given the absence of such changes in the SSNox4-/- and SD rats. Metabolite responses and their relationship with transcriptomic changes are currently being analyzed. Funding: Other NIH Support - NHLBI, Private Foundation Support