ESSENTIALITY OF INSULIN FOR THE ACCUMULATION OF RAT MILK PROTEIN MRNA'S

乳腺体外显性分化的调控涉及一种 多肽和类固醇激素之间的相互作用。胰岛素, 氢化可的松和催乳素是表达 牛奶蛋白基因。个体荷尔蒙的作用正在研究中。这些 研究表明：1)在糖皮质激素和催乳素存在的情况下 胰岛素是牛奶蛋白基因表达所必需的。 在本研究中发现，25K的累积效应 大鼠酪蛋白mRNA不反映转录的稳定性 胰岛素。相反，在胰岛素存在的情况下，胰岛素对其合成是必不可少的 糖皮质激素和催乳素。因此，胰岛素可以被认为是一种 乳腺系统中的发育激素。无论是胎牛血清还是 增殖刺激活性(MSA)或表皮生长因子(EGF) 可以替代胰岛素对分化的影响，尽管这些激素可以 维持乳腺细胞在培养中的可塑性。2)有绝对的 需要氢化可的松来积累这些信息， 乳腺组织中42K酪蛋白mRNA的积聚 摘除肾上腺后，处女大鼠的体重几乎增加了20倍 外源性氢化可的松在其不存在的情况下。25K酪蛋白的积累 信使核糖核酸也完全依赖类固醇。

The control of overt differentiation of mammary gland in vitro involves an interplay between polypeptide and steroid hormones. Insulin, hydrocortisone and prolactin are absolutely required for the expression of milk protein genes. Role of individual hormones is being studied. These studies have shown: 1) In the presence of glucocorticoid and prolactin insulin is absolutely required for the expression of milk protein genes. In the present study it was shown that the accumulation effect on the 25K rat casein mRNA does not reflect stabilization of the transcript by insulin. Rather, insulin is essential for its synthesis in the presence of glucocorticoid and prolactin. Thus, insulin can be considered as a developmental hormone in the mammary system. Neither fetal calf serum nor Multiplication stimulating activity (MSA) or epidermal growth factor (EGF) can substitute insulin effect on differentation, though these hormones can sustain mammary cell vability in culture. 2) There is absolute requirement of hydrocortisone for accumulation of these messages, specifically the accumulation of 42K casein mRNA in mammary tissue from adrenalectomized, virgin rat is almost 20x higher in the presence of exogenous hydrocortisone than in its absence. Accumulation of 25K casein mRNA is also totally dependent on the steroid.