蛋氨酸限制对高脂饮食小鼠甲状腺激素和骨骼肌线粒体生物合成的影响

Objective: To investigate the effects ofmethionine restricted high-fat dietonthyroid hormones and skeletal muscle mitochondria content and function in mice. Methods: A total of twenty-seven male C57BL/6 mice were randomly divided into controlfeeding diet(CON), high-fat diet (HFD) and methionine restricted-highfat diet(MR-HFD). In 22th week, the energy metabolism was measured by comprehensive laboratory animal monitoring system (CLAMS) and then the mice were sacrificed.Thyroid glandhistological analysis was performedby microscopy. The plasma levels of lipids, thyroid hormones and the skeletal muscle levels of deiodinase 2 (DIO2) activity, mitochondrial membrane potential (MMP), ATP content were detected. Mitochondrial DNA (mtDNA) copy number, relative mRNA expression of DIO2, and mitochondrial biogenesis related genes PGC-1α, TFAM and ATP6 were determined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Results: Compared to HFD group, the average body weight was significantly decreased by methionine restriction (P<0.05), while the level of energy intake and energy expenditure were significantly increased (P<0.05).In plasma, methionine restriction significantly decreased the level of lipids (P<0.05), while the level of thyroid hormones was significantly increased(P<0.05). In skeletal muscle, the level of DIO2 activity, MMP, ATP, mitochondrial DNA copy number and the mRNA expression of DIO2, PGC1α, TFAM, ATP6 were significantlyincreased in MR-HFD group than those in HFD group (P<0.05). Conclusion: Methionine restriction may enhance skeletal muscle mitochondria content and function by increasing T3 profited from both improvement of thyroid gland function and the high expression of skeletal muscles DIO2 in high fat diet mice. As a consequence, the energy metabolism of skeletal muscle was accelerated and the weight of mice was reduced.