Chronic rosiglitazone therapy normalizes expression of ACE1, SCD1 and other genes in the kidney of obese Zucker rats as determined by microarray analysis

Thiazolidinediones increase tissue insulin sensitivity and are protective against worsening of nephropathy and hypertension in diabetes. Mechanisms underlying protection at the renal level likely involve a variety of unknown changes ingene expression. We examined kidney gene expression in obese and lean Zucker rats in response to rosiglitazone (Avandia (R)), a peroxisome proliferator activated receptor (T-subtype) agonist. Lean and obese Zucker rats were treated with either control chow or chow with added rosiglitazone (3mg/kg.bw) for 12 weeks (n=3/group). Total kidney mRNA expression was evaluated using the Affymetrix Rat Genome 230 2.0 GeneChip. 903 probe sets were significantly (P<0.05) altered with at least 1.5-fold changes between groups. In untreated obese rats, 300 probe sets were increased and 244 decreased, relative to lean. increased genes included the beta-subunit of the epithelial sodium channel (ENaC), the thiazidesensitive Na-Cl cotransporter, and aquaporin 3. Decreased genes included angiotensin converting enzyme, type 1 (ACE1). FatiGO analysis showed that the highest number of altered genes between lean and obese belonged to the categories: ion binding, hydrolase activity, and protein binding. RGZ increased expression of uncoupling protein 1 (UCP1), CD36, and fatty acid binding protein 4 (FAbp4) in both lean and obese rats. In obese rats, 33 genes were normalized by RGZ (no longer different from lean) including ACE1, fatty acid synthase (Fasn), and stearoyl-coenzyme A desaturase (SCD1). Ingenuity Pathways System analysis of genes upregulated by RGZ in obese rats revealed two major nodes affected: PPAR-gamma and tumor necrosis factor alpha (TNF-alpha).