Objective: Lipid accumulation in skeletal muscle and the liver is strongly implicated in the development of insulin resistance and type 2 diabetes, but the mechanisms underpinning fat accrual in these sites remain incompletely understood. Accumulating evidence of muscle mitochondrial dysfunction in insulin-resistant states has fuelled the notion that primary defects in mitochondrial fat oxidation may be a contributory mechanism. The purpose of our study was to determine whether patients with congenital lipodystrophy, a disorder primarily affecting white adipose tissue, manifest impaired mitochondrial oxidative phosphorylation in skeletal muscle. Research Design and Methods: Mitochondrial oxidative phosphorylation was assessed in quadriceps muscle using P-31-magnetic resonance spectroscopy measurements of phosphocreatine recovery kinetics after a standardized exercise bout in nondiabetic patients with congenital lipodystrophy and in age-, gender-, body mass index-, and fitness-matched controls. Results: The phosphocreatine recovery rate constant (k) was significantly lower in patients with congenital lipodystrophy than in healthy controls (P < 0.001). This substantial (similar to 35%) defect in mitochondrial oxidative phosphorylation was not associated with significant changes in basal or sleeping metabolic rates. Conclusions: Muscle mitochondrial oxidative phosphorylation is impaired in patients with congenital lipodystrophy, a paradigmatic example of primary adipose tissue dysfunction. This finding suggests that changes in mitochondrial oxidative phosphorylation in skeletal muscle could, at least in some circumstances, be a secondary consequence of adipose tissue failure. These data corroborate accumulating evidence that mitochondrial dysfunction can be a consequence of insulin-resistant states rather than a primary defect. Nevertheless, impaired mitochondrial fat oxidation is likely to accelerate ectopic fat accumulation and worsen insulin resistance.
Mitochondrial oxidative phosphorylation is impaired in patients with congenital lipodystrophy / Sleigh A;Stears A;Thackray K;Watson L;Gambineri A;Nag S;Campi VI;Schoenmakers N;Brage S;Carpenter TA;Murgatroyd PR;O'Rahilly S;Kemp GJ;Savage DB. - In: THE JOURNAL OF CLINICAL ENDOCRINOLOGY AND METABOLISM. - ISSN 0021-972X. - STAMPA. - 97:(2012), pp. 438-442. [10.1210/jc.2011-2587]
Mitochondrial oxidative phosphorylation is impaired in patients with congenital lipodystrophy.
GAMBINERI, ALESSANDRA;
2012
Abstract
Objective: Lipid accumulation in skeletal muscle and the liver is strongly implicated in the development of insulin resistance and type 2 diabetes, but the mechanisms underpinning fat accrual in these sites remain incompletely understood. Accumulating evidence of muscle mitochondrial dysfunction in insulin-resistant states has fuelled the notion that primary defects in mitochondrial fat oxidation may be a contributory mechanism. The purpose of our study was to determine whether patients with congenital lipodystrophy, a disorder primarily affecting white adipose tissue, manifest impaired mitochondrial oxidative phosphorylation in skeletal muscle. Research Design and Methods: Mitochondrial oxidative phosphorylation was assessed in quadriceps muscle using P-31-magnetic resonance spectroscopy measurements of phosphocreatine recovery kinetics after a standardized exercise bout in nondiabetic patients with congenital lipodystrophy and in age-, gender-, body mass index-, and fitness-matched controls. Results: The phosphocreatine recovery rate constant (k) was significantly lower in patients with congenital lipodystrophy than in healthy controls (P < 0.001). This substantial (similar to 35%) defect in mitochondrial oxidative phosphorylation was not associated with significant changes in basal or sleeping metabolic rates. Conclusions: Muscle mitochondrial oxidative phosphorylation is impaired in patients with congenital lipodystrophy, a paradigmatic example of primary adipose tissue dysfunction. This finding suggests that changes in mitochondrial oxidative phosphorylation in skeletal muscle could, at least in some circumstances, be a secondary consequence of adipose tissue failure. These data corroborate accumulating evidence that mitochondrial dysfunction can be a consequence of insulin-resistant states rather than a primary defect. Nevertheless, impaired mitochondrial fat oxidation is likely to accelerate ectopic fat accumulation and worsen insulin resistance.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.