During overwintering in aquaculture, fish are subjected to the coordinated stress of low temperature and starvation. This study investigates the physiological strategies in response to overwintering in grass carp, including glucose and lipid utilization. Grass carp were sampled at 0, 8, and 16 weeks of overwintering. Then, body composition, antioxidant enzyme activities, fatty acid composition, as well as glucose and lipid metabolic gene expression were determined in hepatopancreas, muscle, and adipose tissue. The results indicated that the three tissues exhibited distinct glucose and lipid metabolisms during overwintering. During overwintering, lipolysis was activated in adipose tissue through influencing ATGL gene expression. In hepatopancreas, triglycerides were also utilized during overwintering; starvation of 8 weeks significantly increased the glycogen content via gluconeogenesis activation, but the glycogen content remained steady from the 8th to the 16th week. The muscle firstly utilized glycogen via glycolysis, followed by triglycerides as energy substrates. Interestingly, starvation of 8 weeks significantly increased the triglycerides content of muscle, which may be dependent on LPL-mediated lipid transport mechanism. Hence, during overwintering, glucose was used mainly during the early stage, and muscle was the main utilization site, while lipids were utilized during the whole stage. According to the results indicating that lipids were continuously utilized as energy substrates, antioxidant enzyme activities demonstrated that adipose tissue is one of the most vulnerable tissues to oxidative stress. In addition, principal component analysis (PCA) of fatty acid composition indicated that SFA was the predominant fatty acid used by grass carp during overwintering. Our results provide critical fundamental information for understanding the physiological responses to overwintering stress and development of nutritional feed before and after overwintering in grass carp.

在水产养殖越冬过程中，鱼类受到低温和饥饿的协同胁迫。本研究调查了草鱼越冬的生理策略，包括葡萄糖和脂质的利用。在越冬的第 0、8 和 16 周对草鱼进行取样。然后，测定了肝胰腺、肌肉和脂肪组织中的身体成分、抗氧化酶活性、脂肪酸组成以及葡萄糖和脂质代谢基因的表达。结果表明，三种组织在越冬期间表现出不同的葡萄糖和脂质代谢。在越冬期间，脂肪组织中的脂肪分解通过影响 ATGL 基因表达而被激活。在肝胰腺中，甘油三酯也在越冬期间被利用；饥饿 8 周通过糖异生激活显着增加糖原含量，但糖原含量从第 8 周到第 16 周保持稳定。肌肉首先通过糖酵解利用糖原，然后是甘油三酯作为能量底物。有趣的是，饥饿 8 周显着增加了肌肉的甘油三酯含量，这可能取决于 LPL 介导的脂质转运机制。因此，越冬早期主要利用葡萄糖，肌肉是主要利用部位，而整个阶段利用脂质。结果表明，脂质被持续用作能量底物，抗氧化酶活性表明脂肪组织是最容易受到氧化应激的组织之一。此外，脂肪酸组成的主成分分析 (PCA) 表明 SFA 是草鱼在越冬期间使用的主要脂肪酸。我们的研究结果为了解草鱼越冬胁迫前后的生理反应和营养饲料的发育提供了重要的基础信息。