糖类是最廉价的能量物质，但鱼类对其利用率较低。日粮中过高糖水平导致鱼体代谢紊乱，并诱发多种营养代谢病。前期研究发现，鱼体糖代谢紊乱与线粒体功能损伤有关，且PGC1β在鱼体线粒体生物合成及功能调控中发挥重要作用，但潜在机制尚不明确。基于此，本项目利用基因沉默技术明确PGC1β在团头鲂肝细胞线粒体生物合成及功能调控中的作用。在此基础上，探讨AMPK介导的磷酸化修饰对PGC1β活性的调节作用以及PGC1β对NRF1活性的调节作用，并确定NRF1下游分子，进而明确PGC1β调节线粒体功能的途径。此外，结合体内、外试验，通过高糖诱导肝细胞线粒体功能损伤，初步阐明PGC1β介导的高糖诱导团头鲂线粒体功能损伤机理。上述研究可以初步阐明高糖诱导鱼体糖代谢紊乱的机理，部分揭示鱼类糖代谢障碍分子机制，并为高糖饲料在水产养殖中的应用提供参考。

Carbohydrates are the cheapest energy source for fish. However, unlike the case of mammals, fish appears to have a limited capability to use dietary carbohydrate for energy purposes. High-carbohydrate diets usually results in metabolic disorders of fish, as inevitably leads to nutritional and metabolic diseases. Our previous studies suggested that this might be ascribed to the mitochondrial dysfunction of fish. In addition, we found that peroxisome proliferator-activated receptor γ coactivator-1β (PGC1β) is closely involved in the mitochondrial biogenesis and function of fish. However, the potential mechanisms are still poorly understood. Bearing this in mind, using Megalobrama amblycephala as the target animal, the present study aims to 1) ascertain the roles of PGC1β in the mitochondrial biogenesis and function in hepatocytes in vitro through RNA interference; 2) illustrate the activation mechanisms of PGC1β through the phosphorylation mediated by AMP-activated protein kinase (AMPK) ; 3) investigate the activation mechanisms of nuclear respiration factor 1 (NRF1) through the transcriptional regulation of PGC1β ; 4) identify the target molecules of NRF1 ; and 5) alter the mitochondrial biogenesis and function in hepatocytes through glucose manipulations, and investigate the potential mechanisms mediated by the AMPK-PGC1β-NRF1 pathway. The results obtained here will partly illustrate the potential mechanisms by which PGC1β regulates the mitochondrial function of blunt snout bream Megalobrama amblycephala fed high-carbohydrate diets. It will also facilitate our understanding of the carbohydrate utilization by fish, as would benefit the development and application of high-carbohydrate feed in the aquaculture industry.