Turner J D, Huynh H T
Department of Animal Science Macdonald College of McGill University Ste. Anne de Bellevue, PQ, Canada.
J Dairy Sci. 1991 Aug;74(8):2801-7. doi: 10.3168/jds.S0022-0302(91)78460-9.
Lactation is a physiological process characterized by the secretion of large quantities of protein, carbohydrate, and lipid. To achieve the production, the mammary gland must grow and then differentiate; both processes require extensive tissue remodeling. Remodeling begins with a carefully controlled proteolysis of the extracellular matrix and cell-cell adhesion proteins. Plasmin is a serine protease that has been implicated in the tissue remodeling associated with the declining phase of lactation and mammary involution. As lactation progresses, the quantity of plasmin activity increases within the mammary tissue and milk. This has led to the hypothesis that gradual involution results from progressive tissue remodeling. Hormonal attenuation of gradual involution by bST would slow tissue remodeling and would be permissive for lactation. In vitro results indicate that insulin-like growth factor-I impairs the secretion of plasminogen activator by bovine mammary epithelial cells. As such, a mechanism of action for bST exists.
泌乳是一个以大量蛋白质、碳水化合物和脂质分泌为特征的生理过程。为实现乳汁分泌，乳腺必须生长然后分化；这两个过程都需要广泛的组织重塑。重塑始于对细胞外基质和细胞间黏附蛋白的精确控制的蛋白水解。纤溶酶是一种丝氨酸蛋白酶，它与泌乳后期和乳腺退化相关的组织重塑有关。随着泌乳的进行，乳腺组织和乳汁中纤溶酶活性的量会增加。这导致了这样一种假说，即渐进性退化是由渐进性组织重塑引起的。bST对渐进性退化的激素抑制作用会减缓组织重塑，并有利于泌乳。体外实验结果表明，胰岛素样生长因子-I会损害牛乳腺上皮细胞纤溶酶原激活物的分泌。因此，bST的作用机制是存在的。
