米糠蛋白改善大鼠脂质代谢作用及机制研究

为了讨论米糠蛋白对高脂饮食状态大鼠脂质代谢的影响及作用机制。试验设计酪蛋白组（CAS，对照组）、米糠蛋白组（RBP）、糙米蛋白组（BRP）和大米蛋白组（WRP）等4组，饲喂大鼠分别添加了质量分数20%酪蛋白、15%酪蛋白+5%米糠蛋白、15%酪蛋白+5%糙米蛋白和15%酪蛋白+5%大米蛋白的高胆固醇饲料3周。实验测定大鼠血清总胆固醇（TC）水平、甘油三酯（TG）浓度以及肝脏TC、TG和总脂质的含量，并收集了实验后期3 d的粪便，测定其总胆汁酸和中性固醇的排泄量。采用体外模拟人体胃肠消化道环境试验，测定CAS、RBP、BRP及WRP对胶束溶解度的抑制率和不同浓度RBP的胆汁酸结合能力。结果显示，高纯度米糠蛋白与酪蛋白和其他蛋白组相比较能明显降低高胆固醇饲喂大鼠的血清TC（P<0.05）以及动脉粥样硬化指数（P<0.05），肝脏TC水平显著降低（P<0.05），粪便中总胆汁酸排泄量显著增加（P<0.05）。体外实验结果表明，米糠蛋白能与胆汁酸相结合，显著抑制了胆固醇胶束溶解度（P<0.05）。综上所述，米糠蛋白在体内与胆汁酸相结合，抑制其在肠道的吸收，增加其粪便中的排泄量，最后达到降血脂的作用。

Effects of Rice Bran Protein on Lipid Metabolism and Its Mechanism in Rats

This study investigated the effects of rice bran protein on lipid metabolism and its mechanism in rats fed with high-cholesterol diet. The experiment designed 4 groups including casein group (CAS, control), rice bran protein group(RBP), brown rice protein group (BRP) and rice protein group(WRP). The rats were fed with high-cholesterol diet supplemented with 20% casein, 15% casein+5% rice bran protein, 15% casein+5% brown rice protein and 15% casein+5% rice protein for 3 weeks. The levels of total cholesterol (TC) and contents of triglyceride (TG) in serum, and TC, TG and total lipid in liver of rats were measured. The feces were collected for 3 days before the animals were sacrificed, and the excretion of total bile acids and neutral sterols were determined. The micellar solubility of cholesterol with CAS, RBP, BRP and WRP, and the abilities of different concentrations CAS and RBP to bind with bile acid were determined by simulating human gastrointestinal environment in vitro. The results showed that compared with casein and other protein groups, rice bran protein significantly reduced serum TC (P<0.05) and atherosclerotic index (P<0.05); liver TC level was significantly reduced (P<0.05) and the total bile acid excretion in feces was significantly increased (P<0.05). The in vitro experiments showed that rice bran protein could bound to bile acids and significantly inhibited the solubility of cholesterol micelles (P<0.05). To sum up, rice bran protein bound to bile acids in vivo to inhibit its absorption in the intestines and increase its excretion in feces, and finally achieved the effects of reducing serum lipids.