精氨酸对许氏平鲉豆粕型肠炎的修复作用研究

The repairing effect of arginine on soybean meal-induced enteritis of Sebastes schlegelii

中文关键词: 许氏平鲉  精氨酸  豆粕型肠炎  紧密连接蛋白  炎症因子

英文关键词: Sebastes schlegelii  Arginine  Soybean meal-induced enteritis  Tight junction protein  Inflammatory factor

中文摘要:

      为研究精氨酸(Arg)对患有豆粕型肠炎(SBMIE)的许氏平鲉(Sebastes schlegelii)生长性能、Arg代谢、肠道组织结构、抗氧化性能、肠道紧密连接蛋白基因(occludin、clnd15和zo-1)及炎症因子基因(il-1β、il-8、il-15和tlr8)和抗炎因子基因(il-12b)表达量的影响，以(54.97±0.12) g已诱导出SBMIE的许氏平鲉为研究对象，基础配方中添加30%豆粕，以Arg 0添加为对照组(D0)，添加1%、2%和3% Arg为处理组(D1、D2和D3)，配制4组等氮等能的实验饲料，每组3个重复，每个重复40尾鱼，进行为期6周的养殖实验。结果显示，D2和D3组实验鱼增重率显著升高(P<0.05)，各处理组肝体比和脏体比均显著低于D0组，肥满度显著高于D0组(P<0.05)；处理组血清二胺氧化酶(DAO)、诱导型一氧化氮合成酶(iNOS)活性及一氧化氮(NO)含量显著降低(P<0.05)，D2和D3组总一氧化氮合成酶(T-NOS)活性显著降低(P<0.05)；Arg显著提高了实验鱼肠道皱襞高度(P<0.05)；处理组肠道总抗氧化能力显著升高，并以D2组最高(P<0.05)，D2和D3组丙二醛含量显著降低(P<0.05)；相比较D0组，各处理组occludin mRNA相对表达量显著上调，D2组clnd15 和D1组zo-1 mRNA相对表达量显著上调(P<0.05)；处理组肠道il-1β、il-15和tlr8 mRNA相对表达量显著下调，il-12b mRNA相对表达量显著上调(P<0.05)。综上所述，在本实验条件下，高豆粕饲料中添加Arg能显著提高SBMIE-许氏平鲉的生长性能和抗氧化性能，改善Arg代谢和肠道组织结构，上调肠道紧密连接蛋白和抗炎因子基因相对表达量，下调炎症因子基因相对表达量。Arg (2%最佳)对许氏平鲉SBMIE具有修复作用。本研究为Arg修复SBMIE的机制提供了理论依据。

英文摘要:

      The complete intestinal structure is important to ensure the rapid and h ealthy growth of fish. However, the feed composition, aquaculture water environment, intestinal microbial population, and other factors may affect the intestinal health of fish. Intestinal health problems caused by feed ingredients are mainly due to the antinutrient factors contained in raw materials. Antinutritional factors contained in high-level soybean meal can cause oxidative damage to the intestine, thus, inducing soybean meal-induced enteritis (SBMIE), which leads to a decreased appetite and the slow growth of fish. Alleviating the damage of soybean meal to the fish intestinal tract and improving intestinal health through nutrition are essential methods for ensuring the sustainable development of the feed industry, which has significant ecological and economic significance. As a functional amino acid, arginine is a precursor to the synthesis of bioactive substances, such as urea, glutamic acid, creatine, proline, polyamine, and nitric oxide. Arginine modulates metabolic regulation, including growth, immunity, intestinal barrier, and endocrine regulation. It plays a vital role in the immune regulation, maintenance, and protection of the intestinal mucosal structure and function. It has been reported that arginine is beneficial for repairing intestinal mucosal injury in poultry and aquatic animals. In this study, the carnivorous marine economic fish Sebastes schlegelii (54.97±0.12) g were used to investigate the repair effect and mechanism of arginine on SBMIE. This study aimed to provide a scientific basis for the application of arginine for maintaining the intestinal health of fish and provide a reference for the application of plant protein to the compound feed of the carnivorous economic fish S. schlegelii. The purpose of this study was to investigate the repairing effects of arginine on the growth performance, arginine metabolism, intestinal structure, antioxidant performance, relative expression levels of intestinal tight junction protein genes (occludin, clnd15, and zo-1), and inflammatory factor-related genes (il-1β, il-8, il-15, and tlr8) and anti-inflammatory factor-related gene (il-12b) of S. schlegelii with SBMIE. S. schlegelii were fed high-level soybean meal (40%) for 28 days to induce SBMIE. SBMIE-S. schlegelii weighing (54.97±0.12) g were used as the study animals. Four isonitrogen and isoenergetic experimental feeds were formulated. The basic formula was supplemented with 30% soybean meal, arginine 0 supplementation as the control group (D0), and 1%, 2%, and 3% arginine supplementation as the treatment groups, named D1, D2, and D3, respectively. Each diet group had three replicates, and each replicate consisted of 40 fish. The fish were randomly placed in 12 homemade cages (60 cm × 60 cm × 90 cm). The experiment lasted for 6 weeks. The experimental fish were fed twice a day (08:00 and 17:00), with the initial feeding amount being 1% of the body weight, and the feeding amount being adjusted according to the feeding situation. During the experiment, the bottom of the cages was cleaned, and the water was changed every day to maintain the water temperature at 18~22 ℃, the dissolved oxygen at > 6 mg/L, the pH at 7.6~8.2, the ammonia nitrogen content at < 0.05 mg/L, and the nitrite nitrogen content at < 0.05 mg/L. The light cycle was the natural cycle. The results showed that the weight gain rate of the fish in the D2 and D3 groups was significantly higher than that in D0 group (P<0.05). The hepatosomatic and viscerosomatic indexes of the fish in the arginine treatment groups were significantly lower than those in the D0 group, and the condition factor was significantly higher than that in the D0 group (P<0.05). There was no significant effect on the survival rate (P>0.05). Diamine oxidase (DAO) activity, NO content, and iNOS activity values in the serum of the treatment groups were significantly lower than those in the D0 group (P<0.05). The serum T-NOS activity in the D2 and D3 groups was significantly lower than that in the D0 group (P<0.05). The duplicature height in the treatment groups was significantly higher than that in the D0 group, while no significant difference was found in the duplicature number and muscle thickness (P>0.05). In group D0, the intestinal mucosa lamina propria widened, and the number of goblet cells increased, while in groups supplemented with arginine, the intestinal mucosa was intact, and the problems mentioned above improved significantly. Intestinal total antioxidant capacity (T-AOC) in arginine supplementation groups was significantly increased, and the highest value was found in group D2 (P<0.05). The malondialdehyde content in groups D2 and D3 was decreased significantly compared to that in the D0 group (P<0.05). The relative expression of occludin mRNA in each treatment group was significantly upregulated compared to that in the D0 group (P<0.05). The relative expression level of clnd15 mRNA in the D2 group was significantly higher than that in the D0 and D1 groups (P<0.05). The relative expression level of zo-1 mRNA in group D1 was significantly higher than that in the other groups (P<0.05). The relative expression levels of IL-1β, IL-15, and TLR8 mRNA were downregulated in all treatment groups, while the relative expression of IL-12b mRNA was upregulated (P<0.05). No significant differences were found in IL-8 mRNA relative expression (P>0.05). In conclusion, under the conditions of this experiment, the growth and antioxidant performances of S. schlegelii with SBMIE were significantly increased, arginine metabolism and the intestinal structure were improved significantly, and the relative expression of intestinal tight junction protein and anti-inflammatory factor-related genes was upregulated, while that of inflammatory factor-related genes was downregulated, with arginine supplementation in a high-level soybean meal diet. Arginine (2% best) was effective in repairing SBMIE of S. schlegelii. The results of this study provide a theoretical basis for the mechanism of repairing SBMIE with arginine.