Grigor M R, Carne A, Geursen A, Flint D J
Department of Biochemistry, University of Otago, Dunedin, New Zealand.
J Nutr. 1988 Jun;118(6):669-74. doi: 10.1093/jn/118.6.669.
Milk transferrin in the rat is immunochemically identical to serum transferrin. Its concentration in milk during normal lactation (10 pups for 21 d) varies biphasically, decreasing from a value of 1.5 mg/ml in colostrum to barely detectable values at d 4 and 8 of lactation, and thereafter increasing to reach values of 4 mg/ml at d 21. The effect of extended lactation on transferrin in milk was investigated in two experiments in which litters were replaced by 4-d-old litters at d 8 and 12 of lactation or at d 20 of lactation. Transferrin concentrations in milk in both experiments increased in a similar manner to reach values of 10 mg/ml at d 28 through d 36 of lactation. Serum transferrin and serum insulin and prolactin concentrations were not significantly altered in these experiments. Premature exposure of dams to older pups did not affect the pattern of milk transferrin concentrations. Milk transferrin concentrations were, however, modulated by altering the milk demand (changing litter sizes) and by restricting either the total food intake or the protein content of the diet. These restrictions led to lower transferrin concentrations.
大鼠乳汁中的转铁蛋白在免疫化学上与血清转铁蛋白相同。在正常哺乳期（10只幼崽，持续21天），其在乳汁中的浓度呈双相变化，从初乳中的1.5毫克/毫升降至哺乳期第4天和第8天几乎检测不到的值，此后在第21天升至4毫克/毫升。在两项实验中研究了延长哺乳期对乳汁中转铁蛋白的影响，在这两项实验中，在哺乳期第8天和第12天或第20天，将幼崽换成4日龄的幼崽。两项实验中乳汁中转铁蛋白浓度均以类似方式增加，在哺乳期第28天至第36天达到10毫克/毫升。这些实验中血清转铁蛋白、血清胰岛素和催乳素浓度没有显著变化。母鼠过早接触较大幼崽不影响乳汁转铁蛋白浓度模式。然而，乳汁转铁蛋白浓度可通过改变乳汁需求（改变幼崽数量）以及限制总食物摄入量或饮食中的蛋白质含量来调节。这些限制导致转铁蛋白浓度降低。
