The antianginal ranolazine fails to improve glycaemia in obese liver-specific pyruvate dehydrogenase deficient male mice

Abstract

Aims: Recent studies have demonstrated that stimulating pyruvate dehydrogenase (PDH, gene Pdha1), the rate-limiting enzyme of glucose oxidation, can reverse obesity-induced non-alcoholic fatty liver disease (NAFLD), which can be achieved via treatment with the antianginal ranolazine. Accordingly, our aim was to determine whether ranolazine's ability to mitigate obesity-induced NAFLD and hyperglycaemia requires increases in hepatic PDH activity. Methods: We generated liver-specific PDH-deficient (Pdha1Liver−/−) mice, which were provided a high-fat diet for 12 weeks to induce obesity. Pdha1Liver−/− mice and their albumin-Cre (AlbCre) littermates were randomized to treatment with either vehicle control or ranolazine (50 mg/kg) once daily via oral gavage during the final 5 weeks, following which we assessed glucose and pyruvate tolerance. Results: Pdha1Liver−/− mice exhibited no overt phenotypic differences (e.g. adiposity, glucose tolerance) when compared to their AlbCre littermates. Of interest, ranolazine treatment improved glucose tolerance and mildly reduced hepatic triacylglycerol content in obese AlbCre mice but not in obese Pdha1Liver−/− mice. The latter was independent of changes in hepatic mRNA expression of genes involved in regulating lipogenesis. Conclusions: Liver-specific PDH deficiency is insufficient to promote an NAFLD phenotype. Nonetheless, hepatic PDH activity partially contributes to how the antianginal ranolazine improves glucose tolerance and alleviates hepatic steatosis in obesity.