Faculty of Human Life Sciences, Fuji Women's University, Ishikari, Japan.
J Nutr. 2011 Nov;141(11):1975-81. doi: 10.3945/jn.111.144246. Epub 2011 Sep 21.
We previously reported that consumption of a resistant protein, sericin, reduces colon tumorigenesis, constipation, and serum TG in rodents. The present study was conducted to elucidate the effects of dietary sericin on the intestinal luminal environment in rats fed a high-fat (HF) diet. Rats were fed 300 or 50 g/kg of beef tallow with or without 40 g/kg sericin, a protein purified from cocoons of Bombix mori, for 3 wk. Intestinal luminal variables, including IgA (index of intestinal immune function), mucins (index of barrier function), organic acids, microflora, and secondary bile acids, were measured. Dietary sericin markedly elevated fecal IgA in the HF diet group (3-fold, P < 0.05) but not in the low-fat (LF) diet group. Fecal mucin levels were elevated by sericin intake in the HF diet group (P < 0.05). Cecal organic acids, including acetate, propionate, n-butyrate, and succinate, were significantly lower in the HF diet group compared with the LF diet group. Dietary sericin significantly elevated cecal acetate and n-butyrate in the HF diet group but not in the LF diet group. Compared with the LF diet, the HF diet significantly increased serum TG in the untreated group but not in those fed sericin. The HF diet increased lower density lipoprotein (VLDL + IDL + LDL) cholesterol and it was reduced by sericin intake (P < 0.05). There was an inverse correlation between serum TG and cecal acetate (Spearman rank correlation coefficient = -0.63; P < 0.001). The profile of microflora in cecal digesta and fecal secondary bile acids (a risk factor for colon cancer) did not differ between the HF diet and HF diet with sericin groups. These results suggest a novel and favorable effect of sericin on colon health by modulating intestinal immune and barrier functions and fermentation in rats fed a HF diet.
我们之前报道过，摄入一种抗性蛋白丝胶可以减少啮齿动物的结肠肿瘤形成、便秘和血清甘油三酯。本研究旨在阐明膳食丝胶对高脂肪（HF）饮食喂养大鼠肠道腔内环境的影响。大鼠喂食 300 或 50g/kg 的牛脂，或同时喂食 40g/kg 的丝胶（一种从 Bombyx mori 茧中提取的蛋白质），为期 3 周。测量肠道腔内变量，包括 IgA（肠道免疫功能指标）、粘蛋白（屏障功能指标）、有机酸、微生物群和次级胆汁酸。膳食丝胶显著增加了 HF 饮食组的粪便 IgA（增加 3 倍，P<0.05），但 LF 饮食组没有。丝胶摄入使 HF 饮食组的粪便粘蛋白水平升高（P<0.05）。与 LF 饮食组相比，HF 饮食组的盲肠有机酸，包括乙酸、丙酸、正丁酸和琥珀酸，显著降低。膳食丝胶显著增加了 HF 饮食组的盲肠乙酸和正丁酸，但对 LF 饮食组没有影响。与 LF 饮食相比，HF 饮食未喂食丝胶的大鼠血清甘油三酯显著增加，但喂食丝胶的大鼠则没有。HF 饮食增加了低密度脂蛋白（VLDL+IDL+LDL）胆固醇，而丝胶摄入则降低了它（P<0.05）。血清甘油三酯与盲肠乙酸呈负相关（Spearman 秩相关系数=-0.63；P<0.001）。盲肠内容物和粪便次级胆汁酸（结肠癌的一个危险因素）的微生物群谱在 HF 饮食组和 HF 饮食加丝胶组之间没有差异。这些结果表明，丝胶通过调节大鼠 HF 饮食喂养的肠道免疫和屏障功能以及发酵，对结肠健康具有新颖和有益的影响。
