越冬饥饿胁迫对草鱼机体生化组成和糖脂蛋白代谢相关基因转录水平的影响

OVERWINTER STARVATION ON BIOCHEMICAL COMPOSITION AND TRANSCRIPTIONAL LEVEL OF GLUCOSE-LIPID-PROTEIN METABOLISM RELATED GENES TRANSCRIPTION LEVEL IN GRASS CARP (CTENOPHARYNGODON IDELLUS)

  • 摘要: 为了探讨草鱼(Ctenopharyngodon idellus)在越冬期间能量利用的代谢适应机制, 将草鱼初始体重(1053.33±16.11) g置于室外水泥培育池, 分别在自然越冬饥饿0、1、2、4、8、12和16周后进行采样, 进行肌肉常规成分、血清能量代谢物、组织糖原、甘油三酯含量及AMP活化蛋白激酶和糖脂蛋白代谢相关基因转录水平的检测。结果显示: 越冬饥饿1周后, 草鱼肌肉各常规成分含量显著变化(P<0.05); 随着越冬饥饿时间的延长, 血清甘油三酯(TG)、甘油(Glycerol)、总蛋白(TP)、总胆固醇(TCHO)和血糖(GLU)含量先显著降低(P<0.05), 随后保持稳定, 游离脂肪酸(Free fatty acids)含量显著上升(P<0.05); 肝胰脏糖原和肌肉糖原及肝胰脏、肌肉和脂肪组织TG含量显著降低(P<0.05); 血清ATP、ADP和AMP含量显著降低, ADP+AMP/ATP比值显著升高(P<0.05); 肝胰脏、肌肉及腹腔脂肪ampk α1ampk α2基因表达显著上升(P<0.05), 下游糖脂及蛋白代谢相关基因转录水平显著上升(包括atglhslcpt1αcd36等脂分解相关基因; gkpfkpk等糖酵解相关基因; gldhigf-1等蛋白分解相关基因)或显著下调(accfas等脂合成相关基因; crebfoxo1pgc-1αpepckg6paseglut2等糖异生相关基因; tors6k等蛋白合成相关基因)(P<0.05)。研究表明, 草鱼在越冬饥饿期间, 血清、肝胰脏、肌肉和脂肪组织生化组成发生了上述变化的同时, 越冬饥饿胁迫激活了AMPK通路, 促进了各组织糖酵解、脂质分解、脂肪酸β氧化、脂肪酸转运及蛋白分解的进程, 抑制了糖原合成、脂质合成和蛋白合成的过程, 进而维持了机体能量稳态。

     

    Abstract: Overwinter starvation is one of the environmental stress factors in grass carp Ctenopharyngodon idellus culture. During the overwinter starvation process, the energy mobilization mechanism of grass carp may be different from that under normal conditions. Although someone have studied the metabolism of protein and lipid in grass carp under starvation at a normal situation, the response of glucose, lipid and protein metabolism to overwinter starvation has not been reported. In order to explore the metabolic adaptation mechanism of energy utilization of grass carp during overwinter starvation, 45 fish with the initial body weight of (1053.33±16.11) g were randomly distributed into the three repetitions for natural overwinter starvation. When the water temperature naturally decreased to the point, the grass carp ceased ingestion (water temperature: 15℃), the experiment began. When the water temperature naturally rose to the point, the grass carp refeeding commenced (water temperature: 15℃), the overwinter starvation period, and thus our experiments, concluded. Samples were collected after 0, 1, 2, 4, 8, 12 and 16 weeks of natural overwinter starvation. The contents of muscle routine components, serum energy metabolites, tissue glycogen, triglyceride, and transcription levels of AMP activated protein kinase and glucose-lipid-protein metabolism related genes were detected. The results showed that the content of various conventional components in grass carp muscles changed significantly after overwinter starvation for 1 week (P<0.05); with the extension of overwinter starvation time, serum triglycerides (TG), glycerol, total protein (TP), total cholesterol (TCHO) and blood sugar (GLU) first decreased significantly (P<0.05), then remained stable, and the content of free fatty acids increased significantly (P<0.05); hepatopancreas glycogen and muscle glycogen and the content of TG in hepatopancreas, muscle and adipose tissue reduced significantly (P<0.05); the content of serum ATP, ADP and AMP reduced significantly, and the ratio of ADP+AMP/ATP increased significantly (P<0.05); the expression ofAMPKα1 and AMPKα2 genes in the hepatopancreas, muscle and adipose tissue increased significantly (P<0.05), and the transcription level of downstream glucose-lipid and protein metabolism related genes increased significantly (including ATGL, HSL, CPT1α, CD36 and other lipolysis related genes; GK, PFK, PK and other glycolysis related genes; GLDH, IGF-1 and other proteolysis-related genes) or significantly down-regulated (ACC, FAS and other lipid synthesis-related genes; CREB, FoxO1, PGC-1α, PEPCK, G6Pase, GLUT2 and other gluconeogenesis related genes; TOR, S6K and other related to protein synthesis genes) (P<0.05). The results revealed that grass carp utilized energy storage to maintain its energy homeostasis during the overwinter starvation period with significant changes in the biochemical composition of serum, hepatopancreas, muscle and adipose tissue of grass carp during the overwinter starvation period has undergone significant changes. At the same time, the overwinter starvation activates the AMPK pathway and promotes glycolysis, lipid decomposition, fatty acid β-oxidation, the process of fatty acid transport and protein decomposition inhibits the process of glycogen synthesis, lipid synthesis and protein synthesis, thereby maintaining the body’s energy homeostasis. This study showed that the changes of biochemical components and the regulation of transcription level of glucose-lipid-protein metabolism genes based on AMPK pathway in grass carp during overwinter starvation, and revealed the regulatory content and mechanism of adaptive changes of grass carp during overwinter starvation.

     

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