Mammary gland differentiation in hypophysectomized, pregnant mice treated with corticosterone and thyroxine.
Mammary gland differentiation in hypophysectomized, pregnant mice treated with corticosterone and thyroxine.
复制标题
用皮质酮和甲状腺素治疗的垂体切除怀孕小鼠的乳腺分化。
DOI：
10.1095/biolreprod47.4.676
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发表时间：
1992
影响因子：
3.6
通讯作者：
Talamantes,F
中科院分区：
文献类型：
--
作者：
Thordarson,G;Fielder,P;Lee,C;Hom,YK;Robleto,D;Ogren,L;Talamantes,F
瑞士韦伯斯特小鼠在怀孕第 11 天被切除垂体或进行假手术。对动物进行皮下安装。在垂体切除后立即使用含有溶解在 Molecusol（Pharmatec，Alachua，FL）中的皮质酮（B）或单独载体的渗透微型泵。一些实验组的动物还在饮用水中摄入了甲状腺素（T4）。在妊娠第 18 天处死小鼠，匀浆并提取乳腺组织以评估 DNA、RNA、α-乳清蛋白和 α-酪蛋白。测定血清中的胎盘催乳素-I (PL-I)、胎盘催乳素-II (PL-II)、B 和 T4。垂体切除小鼠血清中 PL-II 的浓度升高，而实验组之间 PL-I 的浓度没有差异。垂体切除术降低了血清中 T4 和 B 的浓度，而施用这些激素可将其血清浓度恢复至正常，或者在某些情况下略高于正常水平。垂体切除术降低了乳腺的总 RNA 含量和 RNA/DNA 比率，但单独使用 B 或 B 和 T4 治疗可将 RNA 水平恢复到假手术动物的水平。单独使用 T4 无法有效恢复 RNA 水平。接受激素治疗（B 和 T4）的假手术动物的乳腺组织中 RNA 水平最高。与所有其他实验组相比，垂体切除的动物乳腺中α-乳清蛋白的含量和浓度降低。用 B 或 T4 治疗使 α-乳清蛋白水平恢复到假手术未治疗动物的水平，但在用 B 和 T4 治疗的假手术和垂体切除小鼠的乳腺中发现了最高的 α-乳清蛋白含量和浓度。 α-酪蛋白的水平不受单独垂体切除术的影响。然而，血清中由垂体切除术产生的PL-II和由外源来源产生的B的血清中伴随的高浓度引起乳腺含量和α-酪蛋白浓度的显着增加。总之，由于 PL-I 和 PL-II 的循环浓度较高，催乳素和生长激素对于小鼠妊娠后半期的正常乳腺分化不是必需的。这项研究还表明，小鼠中乳白蛋白和 α-酪蛋白合成的激素控制是不同的。
Swiss Webster mice were hypophysectomized or sham-operated on Day 11 of pregnancy. The animals were fitted s.c. with osmotic minipumps containing either corticosterone (B) dissolved in Molecusol (Pharmatec, Alachua, FL) or the vehicle alone immediately after they were hypophysectomized. Animals in some of the experimental groups also received thyroxine (T4) in their drinking water. The mice were killed on Day 18 of gestation, and mammary tissue was homogenized and extracted for assessment of DNA, RNA, α-lactalbumin, and α-casein. Serum was assayed for placental lactogen-I (PL-I), and placental lactogen-II (PL-II), B, and T4. The concentration of PL-II in serum was elevated in the hypophysectomized mice, whereas the PL-I concentration did not differ among experimental groups. Hypophysectomy decreased both T4 and B concentrations in serum, and administration of these hormones restored their serum concentrations to normal or, in some cases, somewhat higher than normal levels. Hypophysectomy reduced the total RNA content and RNA/DNA ratio of the mammary gland, but treatment with B alone or with B and T4 restored RNA levels to those of sham-operated animals. T4 alone was ineffective in restoring RNA levels. Sham-operated animals that received hormonal treatment (B and T4) had the highest levels of RNA in the mammary tissue. Hypophysectomized animals had reduced content and concentration of α-lactalbumin in the mammary gland as compared to all other experimental groups. Treatment with either B or T4 brought the levels of a-lactalbumin back up to that of sham-operated untreated animals, but highest content and concentration of α-lactalbumin were found in mammary glands of sham-operated and hypophysectomized mice treated with both B and T4. The levels of α-casein were not affected by hypophysectomy alone. However, concomitant high concentrations In serum of PL-ll, resulting from hypophysectomy, and of B, resulting from an exogenous source, caused a significant increase in the mammary gland content and concentration of α-casein. In conclusion, prolactin and growth hormone are not essential for normal mammary differentiation during the latter half of pregnancy in the mouse, due to high circulating concentrations of PL-I and PL-II. This study also demonstrates that the hormonal control of the synthesis of alactalbumin and of α-casein differ in the mouse.