Menshikova 2017 J Gerontol A Biol Sci Med Sci
|Menshikova EV, Ritov VB, Dube JJ, Amati F, Stefanovic-Racic M, Toledo FG, Coen PM, Goodpaster BH (2017) Calorie restriction-induced weight loss and exercise have differential effects on skeletal muscle mitochondria despite similar effects on insulin sensitivity. J Gerontol A Biol Sci Med Sci 73:81-7.|
Abstract: Skeletal muscle insulin resistance and reduced mitochondrial capacity have both been reported to be affected by aging. The purpose of this study was to compare the effects of calorie restriction-induced weight loss and exercise on insulin resistance, skeletal muscle mitochondrial content, and mitochondrial enzyme activities in older overweight to obese individuals.
Insulin-stimulated rates of glucose disposal (Rd) were determined using the hyperinsulinemic euglycemic clamp before and after completing 16 weeks of either calorie restriction to induce weight loss (N = 7) or moderate exercise (N = 10). Mitochondrial volume density, mitochondria membrane content (cardiolipin), and activities of electron transport chain (rotenone-sensitive NADH-oxidase), tricarboxylic acid (TCA) cycle (citrate synthase) and β-oxidation pathway (β-hydroxyacyl CoA dehydrogenase; β-HAD) were measured in percutaneous biopsies of the vastus lateralis before and after the interventions.
Rd improved similarly (18.2% ± 9.0%, p < .04) with both weight loss and exercise. Moderate exercise significantly increased mitochondrial volume density (14.5% ± 2.0%, p < .05), cardiolipin content (22.5% ± 13.4%, p < .05), rotenone-sensitive NADH-oxidase (65.7% ± 13.2%, p = .02) and β-HAD (30.7% ± 6.8%, p ≤ .03) activity, but not citrate synthase activity (10.1% ± 4.0%). In contrast, calorie restriction-induced weight loss did not affect mitochondrial content, NADH-oxidase or β-HAD, yet increased citrate synthase activity (44.1% ± 21.1%, p ≤ .04). Exercise (increase) or weight loss (decrease) induced a remodeling of cardiolipin with a small (2%–3%), but significant change in the relative content of tetralinoleoyl cardiolipin.
Exercise increases both mitochondria content and mitochondrial electron transport chain and fatty acid oxidation enzyme activities within skeletal muscle, while calorie restriction-induced weight loss did not, despite similar improvements in insulin sensitivity in overweight older adults.
• Keywords: Glucose uptake, Muscle metabolism, Human aging, Caloric restriction, Obesity
• O2k-Network Lab: US FL Orlando Goodpaster BH
Labels: MiParea: Exercise physiology;nutrition;life style Pathology: Diabetes
Organism: Human Tissue;cell: Skeletal muscle