STUDIES OF HEPATIC MAMMARY MITOGENIC FACTORS

我们已经获得证据表明催乳素的促生长作用 (PRL)在鸽粮囊粘膜上皮细胞上参与协同作用 使用胰岛素样生长因子(IGF)。此外，催乳素还能刺激 肝脏分泌这种协同作用的活性，我们称之为Synlactin。 妊娠或哺乳期大鼠的肝脏切片(但不是成年雄性 或处女)在体外分泌合乳素活性，由 作物囊法。因此，当大鼠肝脏分泌该因子时， 器官受到胎盘催乳素水平高的影响(怀孕期间)或 垂体性催乳素(催乳素)。肝灌注液样本中有 (妊娠或哺乳期大鼠)作物囊中的Synlactin活性也 在一项涉及孕妇外植体的试验中具有乳腺有丝分裂活性 大鼠的乳腺。 我们建议确定乳腺中的哪些细胞对 肝乳腺有丝分裂原。未孕或妊娠大鼠的乳腺组织块 将在不含合成乳素的肝脏孵育液中孵化 活性(来自雄性或处女肝脏)或具有活性(来自 怀孕或哺乳的肝脏)。有丝分裂的作用将通过以下方式进行评估 ~3H-胸腺嘧啶核苷掺入细胞的放射自显影分析 原子核。肝脏孵育液的效果将与 人胰岛素样生长因子-I、催乳素和胰岛素以及这些激素对血管内皮细胞生长的影响 将确定不同的组合。病毒的增殖效应 肝脏因子和其他激素(单独和联合使用)会 也可以在大鼠乳腺导管和肺泡细胞的胶原胶中进行测试 矩阵。肝乳腺有丝分裂作用的特异性将是 通过培养其他组织的外植体(唾液腺，肾脏， 在有或没有活性的肝脏孵育液中)。 我们还将调查肝脏是否参与调节 活体内的乳房生长。这将通过注入催乳素来实现 和/或生长激素对处女大鼠肝门静脉的渗透压 附在PE-10套管上的小型泵。这项实验应该表明 催乳素或生长激素可刺激肝脏分泌促进乳腺生长的因子 导管或小叶-肺泡生长。 将尝试用以下方法来提纯和鉴定肝脏因子 肝脏孵育液中Synlactin的活性，并建立了一种用于 这样就可以研究它的生理学的其他方面。

We have obtained evidence that the growth-promoting action of prolactin (PRL) on the mucosal epithelium of the pigeon crop-sac involves synergism with an insulin-like growth factor (IGF). Furthermore, PRL stimulates the liver to secrete this synergistic activity, which we have called synlactin. Slices of liver from pregnant or lactating rats (but not from adult males or virgin females) secrete synlactin activity in vitro as measured by the crop-sac assay. Thus, the factor is secreted by the rat liver when the organ is influenced by high levels of placental lactogen (in pregancy) or pituitary PRL (lactation). The liver inculation medium samples that had synlactin activity in the crop-sac (from pregnant or lactating rats) also had mammary mitogenic activity in an assay involving explants of pregnant rat mammary glands. We propose to determine which cells in the mammary gland respond to the hepatic mammary mitogen. Mammary explants from virgin or pregnant rats will be incubated in liver incubation medium containing no synlactin activity (from male or virgin female liver) or with the activity (from pregnant or lactating liver). The mitogenic effect will be assessed by autoradiographic analysis of the incorporation of 3H-thymidine into cell nuclei. The effects of the liver incubation media will be compared with human IGF-I, PRL and insulin, and the effects of these hormones in different combinations will be determined. The proliferative effects of the hepatic factor and the other hormones (alone and in combination) will also be tested on rat mammary ductal and alveolar cells in a collagen gel matrix. The specificity of the hepatic mammary mitogenic effect will be evaluated by incubating explants of other tissue (salivary gland, kidney, thymus) in liver incubation medium with or without the activity. We will also investigate whether the liver participates in the regulation of mammary growth in vivo. This will be accomplished by infusing PRL and/or GH into the hepatic portal vein of virgin female rats using osmotic minipumps attached to PE-10 cannulae. This experiment should show whether PRL or GH can stimulate the liver to secrete factors that promote mammary ductal or lobulo-alveolar growth. Attempts will be made to purify and characterize the hepatic factor with synlactin activity from liver incubation medium, and to develop an RIA for it so that other aspects of its physiology can studied.