High-fat diet-induced nonalcoholic steatohepatitis is accelerated by low carnitine and impaired glucose tolerance in novel murine models

Abstract

AbstractCarnitine deficiency and impaired glucose tolerance (IGT) exacerbate liver steatosis. Given the current lack of ideal murine nonalcoholic steatohepatitis (NASH) models, we investigated new NASH models using jvs/+ mice with low carnitine and wild-type mice with low-dose alloxan-induced IGT. The jvs/+ and wild-type mice were divided into jvs/+ mice fed a high-fat diet (HFD) from 3 weeks of age (HF hetero group), wild-type mice with low-dose alloxan treatment fed HFD (AL + HF wild group), wild-type mice fed HFD (HF wild group), and two types of mice fed a normal diet—jvs/+ and wild-type (intact group). All mice were sacrificed at 20 or 40 weeks of age. All male HFD-fed mice showed obesity, IGT, high blood insulin levels, homeostatic model assessment of insulin resistance (HOMA-IR), high liver enzyme levels, and high cholesterol levels. The degree of IGT was the worst in the AL + HF wild group, and blood insulin levels and HOMA-IR score were remarkably increased from 20 to 40 weeks of age. Almost all HFD-fed mice showed steatosis, fibrosis, and lobular inflammation in the centrilobular zone. These changes were accompanied by hepatocyte ballooning and were enhanced at 40 weeks of age. Furthermore, the incidence rate of nodular hyperplasia and adenoma in both the HF hetero and AL + HF wild groups was nearly 30%. We successfully established two novel murine models of NASH using male jvs/+ mice with low carnitine and male wild-type mice with IGT that eventually developed obesity, fatty liver, insulin resistance, liver fibrosis, and tumorigenesis. These results suggest that low carnitine levels and early-stage induction of IGT are important factors in the progression of NASH to tumorigenesis, similar to human NASH.