Combining metformin therapy with caloric restriction for the management of type 2 diabetes and nonalcoholic fatty liver disease in obese rats

Melissa A. Linden, Kristi T. Lopez, Justin A. Fletcher, E. Matthew Morris, Grace M. Meers, Sameer Siddique, M. Harold Laughlin, James R. Sowers, John P. Thyfault, Jamal A. Ibdah, R. Scott Rector

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

Weight loss is recommended for patients with nonalcoholic fatty liver disease (NAFLD), while metformin may lower liver enzymes in type 2 diabetics. Yet, the efficacy of the combination of weight loss and metformin in the treatment of NAFLD is unclear. We assessed the effects of metformin, caloric restriction, and their combination on NAFLD in diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Male OLETF rats (age 20 weeks; n = 6–8 per group) were fed ad libitum (AL), given metformin (300 mg・kg-1・day-1; Met), calorically restricted (70% of AL; CR), or calorically restricted and given metformin (CR+Met) for 12 weeks. Met lowered adiposity compared with AL but not to the same magnitude as CR or CR+Met (p < 0.05). Although only CR improved fasting insulin and glucose, the combination of CR+Met was needed to improve post-challenge glucose tolerance. All treatments lowered hepatic triglycerides, but further improvements were observed in the CR groups (p < 0.05, Met vs. CR or CR+Met) and a further reduction in serum alanine aminotransferases was observed in CR+Met rats. CR lowered markers of hepatic de novo lipogenesis (fatty acid synthase, acetyl-CoA carboxylase (ACC), and stearoyl-CoA desaturase-1 (SCD-1)) and increased hepatic mitochondrial activity (palmitate oxidation and β-hydroxyacyl CoA dehydrogenase (β-HAD) activity). Changes were enhanced in the CR+Met group for ACC, SCD-1, β-HAD, and the mitophagy marker BNIP3. Met decreased total hepatic mTOR content and inhibited mTOR complex 1, which may have contributed to Met-induced reductions in de novo lipogenesis. These findings in the OLETF rat suggest that the combination of caloric restriction and metformin may provide a more optimal approach than either treatment alone in the management of type 2 diabetes and NAFLD.

Original languageEnglish (US)
Pages (from-to)1038-1047
Number of pages10
JournalApplied Physiology, Nutrition and Metabolism
Volume40
Issue number10
DOIs
Publication statusPublished - Sep 22 2015
Externally publishedYes

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Keywords

  • Caloric restriction
  • De novo lipogenesis
  • Hepatic steatosis
  • Metformin
  • Mitochondrial function
  • Nonalcoholic fatty liver disease

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Nutrition and Dietetics
  • Physiology (medical)

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