Singh M, Rosen C L, Chang K J, Haddad G G
Department of Pediatrics (Pulmonary Division), Columbia University College of Physicians and Surgeons, New York, New York 10032.
Pediatr Res. 1989 Jul;26(1):34-8. doi: 10.1203/00006450-198907000-00011.
To determine the relation between milk intake and plasma levels of beta-casomorphins as a function of age, we studied the levels of beta-casomorphin-7 immunoreactive material (BCMIR) in 2- and 4-wk-old beagle neonates and adult dogs following milk intake. We used three kinds of milk: 1) bovine casein-based milk formula; 2) canine bitch's milk, and 3) soy protein-based (noncasein) formula. Using a new extraction technique, BCMIR was isolated from plasma and assayed by radioimmunoassay at 0, 2, 4, and 6 h after feeding. We found that BCMIR increased significantly in both 2- and 4-wk-old puppies post bovine and canine milk feeding, but not after soy protein formula. Base-line values were about 80-120 fmol/ml and increased to 100-120% 2 h after bovine casein intake in the older puppies and by 4 h in the younger group. BCMIR levels were undetectable in adult dogs before or after bovine milk feeding. Beta-casomorphin-7 added to plasma was rapidly degraded whereas BCMIR was stable. Chromatographic profiles demonstrated that the BCMIR moiety is larger than beta-casomorphin-7. Our data suggest that the appearance of BCMIR in the plasma of neonatal dogs is a result of beta-casein degradation along a permeable gastrointestinal mucosa. We speculate that morphiceptin and beta-casomorphins can be cleaved from BCMIR and may have important physiologic effects.
为了确定不同年龄阶段牛奶摄入量与血浆中β-酪蛋白吗啡水平之间的关系，我们研究了2周龄和4周龄的比格犬幼犬以及成年犬摄入牛奶后血浆中β-酪蛋白吗啡-7免疫反应性物质（BCMIR）的水平。我们使用了三种牛奶：1）以牛酪蛋白为基础的牛奶配方；2）母犬的乳汁；3）以大豆蛋白为基础（非酪蛋白）的配方。采用一种新的提取技术，在喂食后0、2、4和6小时从血浆中分离出BCMIR，并通过放射免疫分析法进行检测。我们发现，在喂食牛和犬的乳汁后，2周龄和4周龄的幼犬血浆中BCMIR均显著升高，但喂食大豆蛋白配方后未升高。基线值约为80-120 fmol/ml，在年龄较大的幼犬摄入牛酪蛋白后2小时增加到100-120%，在较年轻的组中4小时后增加。成年犬在喂食牛奶前后血浆中均未检测到BCMIR水平。添加到血浆中的β-酪蛋白吗啡-7迅速降解，而BCMIR则稳定。色谱图谱表明，BCMIR部分比β-酪蛋白吗啡-7大。我们的数据表明，新生犬血浆中BCMIR的出现是β-酪蛋白沿渗透性胃肠黏膜降解的结果。我们推测，吗啡肽和β-酪蛋白吗啡可以从BCMIR中裂解出来，可能具有重要的生理作用。
