The role of connective tissue elements in the hormonally induced functional defferentiation of mouse mammary gland in culture

在中孕小鼠乳腺器官培养中，我们建立了酪蛋白和乳白蛋白合成的测定方法。此外，我们研究了生产的胶原蛋白和它的功能，在乳腺在vitro. The胶原蛋白的生产的羟脯氨酸测定和十二烷基硫酸钠聚丙烯酰胺凝胶电泳的测量显示，胶原蛋白的积累，I型和III型在培养的乳腺外植体增加与另外的胰岛素，皮质醇和催乳素的化学成分确定的培养基。当脯氨酸类似物L-氮杂环丁烷-2-羧酸（LACA）在培养开始时以80 μ g/ml的浓度与胰岛素、皮质醇和催乳素一起加入时，培养组织中的胶原蛋白产生被抑制75%，持续3天的孵育期。该试剂还抑制酪蛋白和乳清蛋白的合成，分别约77%和70%。LACA的抑制作用可被L-脯氨酸阻止;同时添加L-脯氨酸（80 μ g/ml）和LACA（80 μ g/ml）可使乳蛋白合成完全恢复到正常水平。LACA，然而，在培养的组织中产生的DNA合成抑制很少。这些结果表明，胶原蛋白的产生可能参与乳蛋白基因的表型表达在激素诱导乳腺上皮分化在体外。

In mammary gland organ culture from midpregnant mice, we have established the method of measurement of casein and -lactalbumin synthesis. Furthermore we examined the production of collagen and its function in the hormone-dependent development of mammary gland in vitro.The measurement of collagen production by the hydroxyproline assay and by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the accumulation of collagen type I and type III in cultured mammary explants increased with the addition of insulin, cortisol and prolactin to a chemically defined medium. When an analog of proline, L-azetidine-2-carboxylic acid (LACA), was added at a concentration of 80 g/ml with insulin, cortisol and prolactin at the beginning of culture, collagen production in cultured tissue was inhibited by 75% curing a 3-day incubation period. This agent also inhibited the synthesis of casein and -lactalbumin by about 77 and 70%, respectively. The inhibitory effect of LACA could be prevented by L-proline; concomitant addition of L-proline (80 g/ml) with LACA (80 g/ml) resulted in complete restoration of milk protein synthesis to normal levels. LACA, however, produced little inhibition of DNA synthesis in cultured tissue. These results suggest that collagen production may be involved in the phenotypic expression of milk protein genes during hormonal induction of mammary epithelial differentiation in-vitro.