高水平烟酸对罗非鱼肝脏脂代谢的作用和机制分析

Excessive lipid deposition in fish body is lipid dysfunction frequently encountered in practical aquaculture, thus how to regulate lipid metabolism of fish occurred this illness is very important to the fish health. Niacin is one of the essential vitamins for organisms. High level niacin could improve lipid metabolism of some mammals suffered abnormal metabolism of lipid (such as nonalcoholic fatty liver disease). But it is little known that whether high level niacin can retard the excessive lipid deposition in fish. Previous research has found that low level niacin affects lipid metabolism in normal lipid deposition fish, whereas the influence of high level niacin on lipid metabolism is unclear yet. Furthermore, nutritional imbalance is considered as one of the main reasons for excessive liver lipid deposition and liver is the most important lipid metabolism organ,therefore, this study will take tilapia as the trial animal, conduct experiments on fish with normal and abnormal fat deposition respectively, to investigate the effects of high level niacin in normal and high carbohydrate-fat feed on lipid content in different body part, physiological and biochemical indexes in blood, lipid metabolism index, related metabolic gene expression level and metabolic composition and structure in liver of tilapia, and to identify and analyze the effects and mechanism of high level niacin on lipid metabolism in liver. The results will be of great and important theoretical value and practical significance for regulation of lipid metabolism and rational application of niacin in feed of tilapia.

体脂沉积过多是在实际生产中经常遇到的鱼类脂代谢异常问题，如何调节此种鱼的脂代谢，对其健康非常重要。烟酸是一种生物必需的维生素，高水平烟酸可明显改善部分脂代谢异常(如非酒精性脂肪肝病)哺乳动物的脂代谢，但目前尚不清楚高水平烟酸对鱼类体脂沉积过多问题是否具有改善作用。前已研究发现低水平烟酸影响体脂正常鱼类脂代谢，但高水平烟酸对其影响知之甚少。同时，因为营养不平衡是导致鱼类体脂沉积过多的主要原因之一，而肝脏是最重要的脂代谢器官，所以本项目以罗非鱼为研究对象，拟分别在鱼体脂沉积正常和过多的生理状态下进行实验，研究正常和高糖高脂饲料中的高水平烟酸对罗非鱼各部位脂肪沉积、血液学指标、肝脏生理生化指标、肝脏中相关基因表达及代谢物成分和肝脏组织学结构的影响，判别并分析高水平烟酸对其肝脏脂代谢的作用和机制，这对鱼类脂代谢的调控以及烟酸在罗非鱼饲料中的合理使用具有重要的理论价值和现实意义。

为研究高水平烟酸对鱼类脂代谢的影响，本项目以罗非鱼为研究对象，探讨了烟酸水平对罗非鱼肝脏脂肪代谢的作用，研究了高水平烟酸对罗非鱼的生长、饲料利用和脂肪积累及肝脏健康状况的影响，分析了了高水平烟酸对罗非鱼脂代谢的作用与机制，研究了高水平烟酸对体脂沉积过多状态下罗非鱼脂代谢的影响；并结合实际生产情况，探讨了烟酸在罗非鱼饲料中的应用。研究结果发现，饲料中添加1000-2000mg/kg烟酸可以改善罗非鱼血脂水平；饲料中添1000mg/kg的烟酸未影响罗非鱼的生长性能、饲料利用效率和肝脏组织学状况，但可以降低肝脏脂肪含量，在某种程度上有利于肝脏结构、改善氧化应激和抑制炎症反应。通过分析脂代谢酶的活性和相关基因的表达发现，高水平烟酸的降脂作用与抑制脂肪和胆固醇的合成，促进脂肪分解，提高胆固醇的转运有关，肝脏代谢组学的分析也进一步支持这个结论。本项目的研究结果为烟酸在鱼类饲料中的合理使用以及鱼类脂肪代谢的调控提供了理论支持。项目资助下已申请国家发明专利1项，发表或已接收的论文包括SCI论文2篇，CSCD核心论文2篇。