The prebiotic fiber inulin ameliorates cardiac, adipose tissue, and hepatic pathology but exacerbates hypertriglyceridemia in rats with metabolic syndrome.

Prebiotics ameliorate dysbiosis and influence metabolism and the immune system, but their effects on cardiovascular complications in metabolic disorders remain largely unknown. We here investigated the effects of the soluble fiber inulin on cardiac, adipose tissue, and hepatic pathology as well as on metabolic disorders in DahlS.Z-Leprfa/Leprfa (DS/obese) rats, an animal model of metabolic syndrome (MetS). DS/obese rats and their homozygous lean (DahlS.Z-Lepr+/Lepr+, or DS/lean) littermate controls were fed a purified diet containing 5% or 20% inulin from 9 to 13 weeks of age. The high-fiber diet ameliorated hypertension, left ventricular inflammation, fibrosis, and diastolic dysfunction, attenuated adipose tissue inflammation and fibrosis as well as alleviated the elevation of interleukin-6 levels, without affecting insulin resistance, in DS/obese rats. In addition, high fiber intake ameliorated lipid accumulation, inflammation, and fibrosis, attenuated the reduction in AMPK activity and the up-regulation of sterol regulatory element binding protein-1c gene expression, and further increased the expression of microsomal triglyceride transfer protein gene, in the liver of DS/obese rats. It also mitigated increases in total and non-high-density lipoprotein-cholesterol levels but increased the triglyceride concentration in serum in these rats. None of these parameters was affected by high dietary fiber in DS/lean rats. The proportion of regulatory T cells in adipose tissue was influenced by dietary fiber but not by genotype. Our results indicate that inulin exacerbates hypertriglyceridemia but alleviates hypertension and cardiac injury as well as adipose tissue and hepatic pathology in MetS rats.