Fiorotto M L, Davis T A, Reeds P J, Burrin D G
USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA.
Pediatr Res. 2000 Oct;48(4):511-7. doi: 10.1203/00006450-200010000-00015.
Colostrum is a complex source of nutrients, immune factors, and bioactive substances consumed by newborn mammals. In previous work, we observed that protein synthesis in the skeletal muscle of newborn piglets is enhanced when they are fed colostrum rather than a nutrient-matched formula devoid of growth factors. To elucidate the mechanisms responsible for this response, we contrasted the fractional rates of sarcoplasmic and myofibrillar protein synthesis of newborn piglets that received only water with those fed for 24 h with colostrum, a nutrient-matched formula, or mature sow's milk. Compared with water, feeding resulted in a 2.5- to 3-fold increase in total skeletal muscle protein synthesis, and this increase was 28% greater in the colostrum-fed than either the formula- or mature milk-fed piglets. Feeding also stimulated muscle ribosome and total polyadenylated RNA accretion. Ribosomal translational efficiency, however, was similar across all fed groups. The greater stimulation of protein synthesis in colostrum-fed pigs was restricted entirely to the myofibrillar protein compartment and was associated with higher ribosome and myosin heavy chain mRNA abundance. Taken together, these data suggest that nonnutritive factors in colostrum enhance ribosomal accretion and muscle-specific gene transcription that, in turn, stimulate specifically the synthesis of myofibrillar proteins in the skeletal musculature of the newborn.
初乳是新生哺乳动物所摄取的营养物质、免疫因子和生物活性物质的复杂来源。在之前的研究中，我们观察到，与喂食不含生长因子的营养匹配配方奶相比，给新生仔猪喂食初乳时，其骨骼肌中的蛋白质合成会增强。为了阐明导致这种反应的机制，我们对比了只饮用清水的新生仔猪与喂食初乳、营养匹配配方奶或成熟母猪奶24小时的新生仔猪的肌浆蛋白和肌原纤维蛋白合成的分数率。与饮用清水相比，喂食使骨骼肌总蛋白合成增加了2.5至3倍，且初乳喂养组的增加幅度比配方奶或成熟奶喂养组的仔猪高28%。喂食还刺激了肌肉核糖体和总多聚腺苷酸化RNA的积累。然而，所有喂食组的核糖体翻译效率相似。初乳喂养的仔猪中蛋白质合成受到的更大刺激完全局限于肌原纤维蛋白部分，并且与更高的核糖体和肌球蛋白重链mRNA丰度相关。综上所述，这些数据表明，初乳中的非营养因子会增强核糖体积累和肌肉特异性基因转录，进而特异性地刺激新生骨骼肌中肌原纤维蛋白的合成。
