Browsing by Author "Kattapuram, Nathan"
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Item The Comparative Effects of Carbohydrates and Lipids on Mitochondrial Function(2020) Kattapuram, Nathan; Sunny, NishanthNon-alcoholic fatty liver disease (NAFLD) and Type 2 Diabetes affect approximately 24% and 8% of the global population respectively. The Western diet, high in both carbohydrates and lipids, is believed to have a role in the development of chronic metabolic disease. Dysfunctional hepatic mitochondrial metabolism is also known to be a central feature of disordered metabolism. The objective of this study was to compare the roles of dietary carbohydrates vs. lipids in inducing dysfunctional hepatic mitochondrial metabolism. Mice, C57BL/6NJ were kept on one of three diets: low-fat control (LF; 10% kcal fat), high-fat (HF; 60% kcal fat), and high-carbohydrate (HC; 25% kcal fat and 34.9% kcal fructose) for 10 weeks. Half of the mice were randomly selected to undergo a 16 hour fast prior to sacrifice, while the other half were not fasted. Within the fasted subset, the HC diet induced significantly elevated basal mitochondrial respiration (pmol Oxygen consumed/min) when compared with HF (HF, 70.1±5.8; HC,108.6±17.4; p<.05). Among fasted mice, the HC diet also appeared to induce significantly higher maximal respiration and ATP production when compared with HF. Expression of hepatic mitochondrial complex proteins were also higher in fasted HC mice than fasted HF mice. Overall, these results suggest that the high-carbohydrate diet enhanced mitochondrial activity when compared with the high-fat diet.Item Dietary Macronutrient Composition Differentially Modulates the Remodeling of Mitochondrial Oxidative Metabolism during NAFLD(MDPI, 2021-04-26) Kattapuram, Nathan; Zhang, Christine; Muyyarikkandy, Muhammed S.; Surugihalli, Chaitra; Muralidaran, Vaishna; Gregory, Tabitha; Sunny, Nishanth E.Diets rich in fats and carbohydrates aggravate non-alcoholic fatty liver disease (NAFLD), of which mitochondrial dysfunction is a central feature. It is not clear whether a high-carbohydrate driven ‘lipogenic’ diet differentially affects mitochondrial oxidative remodeling compared to a high-fat driven ‘oxidative’ environment. We hypothesized that the high-fat driven ‘oxidative’ environment will chronically sustain mitochondrial oxidative function, hastening metabolic dysfunction during NAFLD. Mice (C57BL/6NJ) were reared on a low-fat (LF; 10% fat calories), high-fat (HF; 60% fat calories), or high-fructose/high-fat (HFr/HF; 25% fat and 34.9% fructose calories) diet for 10 weeks. De novo lipogenesis was determined by measuring the incorporation of deuterium from D2O into newly synthesized liver lipids using nuclear magnetic resonance (NMR) spectroscopy. Hepatic mitochondrial metabolism was profiled under fed and fasted states by the incubation of isolated mitochondria with [13C3]pyruvate, targeted metabolomics of tricarboxylic acid (TCA) cycle intermediates, estimates of oxidative phosphorylation (OXPHOS), and hepatic gene and protein expression. De novo lipogenesis was higher in the HFr/HF mice compared to their HF counterparts. Contrary to our expectations, hepatic oxidative function after fasting was induced in the HFr/HF group. This differential induction of mitochondrial oxidative function by the high fructose-driven ‘lipogenic’ environment could influence the progressive severity of hepatic insulin resistance.