Background: The pathogenesis of renal disease in the context of overweight/obesity, metabolic syndrome, and insulin resistance is not completely understood. This may be due to the lack of a definitive animal model of disease, which limits our understanding of obesity-induced renal damage. We evaluated the changes in renal histology and lipid deposits induced by obesity in a model of insulin resistance: the Iberian swine fed with fat-enriched food.
Methods: Twenty-eight female sows were randomized to standard (SD) or high-fat diet (HFD: 6.8% of saturated fat) for 100 days. Weight, adiposity, analytics, oral glucose tolerance tests, and measured renal function were determined. Renal histology and lipid deposits in renal tissue were analyzed.
Results: Animals on HFD developed obesity, hypertension, high levels of LDL cholesterol, triglycerides, insulin resistance, and glomerular hyperfiltration. No animal developed overt diabetes. Animals on HFD showed "diabetoid changes", including mesangial expansion [21.40% ± 4 vs.13.20% ± 4.0, p < 0.0001], nodular glomerulosclerosis [7.40% ± 7, 0.75 vs. 2.40% ± 4.7, p = 0.02], and glomerulomegaly (18% vs. 10%, p = 0.010) than those on SD. Tubular atrophy, interstitial fibrosis, inflammation, arteriolar hyalinosis, or fibrointimal thickening were mild and similar between groups. Triglyceride content in renal tissue was higher in animals on HFD than in SD (15.4% ± 0.5 vs. 12.7% ± 0.7; p < 0.01).
Conclusions: Iberian pigs fed with fat-enriched food showed diabetoid changes and glomerulomegaly as observed in obese humans making this model suitable to study obesity-induced renal disease.