The effect of hypophysectomy on day 12 of pregnancy on the serum progesterone level and time of parturition in the rat.
The effect of hypophysectomy on day 12 of pregnancy on the serum progesterone level and time of parturition in the rat.
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妊娠第12天垂体切除术对大鼠血清孕酮水平和分娩时间的影响。
DOI：
10.1210/endo-91-5-1380
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发表时间：
1972
期刊：
影响因子：
4.8
通讯作者：
I. Rothchild
中科院分区：
文献类型：
--
作者：
G. Pepe;I. Rothchild
在妊娠第12天（第1天：授精第1天）或不手术时分别去垂体和假垂体，观察外周血清黄体酮浓度和分娩时间的变化。用蛋白结合位移法测定黄体酮；在第15天至第26天期间，在一些大鼠和另一些大鼠的尸检中连续采集血液样本。在其他实验中，大鼠的一大组样本提供了第12天的水平值。在完整和去垂体的大鼠中，平均血清孕酮水平从第12天的87.1 ng/ml上升到第15天的约130 ng/ml，并在第19天缓慢下降到约100 ng/ml。在第19天之后，垂体切除大鼠的水平继续以与前相同的速度下降，而在完整的大鼠中，下降速度增加到第19天之前的10倍左右。14只完整大鼠除2只外均在第22或23天分娩；在15只去垂体大鼠中，只有5只分娩，其中3只在第24天或第25天分娩。其余10例中，2例在第23天死亡，8例在第24至26天之间死亡。这些发现表明，血清黄体酮水平的下降与分娩发生之间存在强烈但不是绝对的关系，这与假设(1)黄体生成素（LH）是大鼠怀孕期间必需的黄体素的假设不一致。{内分泌学91:1380,1972)我已经假定，在怀孕期间的大鼠的基本黄体促生成素（LH）和黄体生成素（LH）的分泌不足12天后的黄体生成素的分泌是专门负责(1)孕酮分泌下降（2-8），发生在分娩前在完整的大鼠。然而，这一假设似乎与垂体切除术对怀孕大鼠的某些影响不一致。例如，尽管在第11天（第1天：授精日）之前进行垂体切除术几乎总是会立即导致流产，但在第11天或第12天进行垂体切除术则不会；事实上，妊娠不仅可以维持，而且通常会延长至足月以上，并经常伴有异常和难产（9-11）。黄体酮治疗也延长妊娠期（1,12,13），因此，垂体切除术延迟分娩的显著趋势可能是黄体酮这种作用的一种表现；事实上，alalloiteau et al.（14）的研究结果表明，乳腺、阴道和子宫的情况并不明显。1由USPHS-NIH培训补助金HD00024， NIH合同70-2310和福特基金会培训补助金67-135支持。2生殖生物学博士后（NIH TG HD-00024）；提示垂体切除术引起孕鼠孕酮分泌延长。这些事实似乎足以怀疑Raj和Moudgal的假设(1)的有效性，因为垂体切除的大鼠肯定比完整的大鼠分泌更少的LH。因此，我们做了下面的实验。其目的是比较完整和去垂体妊娠大鼠在第12天至足月期间血清孕酮水平的变化。材料与方法所有大鼠（Sprague-Dawley系；Holtzman鼠公司，Madison, Wisconsin）均在实验室繁殖，以怀孕第1天为授精日。它们被饲养在塑料笼子里，可以自由使用Purina®鼠粮和水，固定的照明时间为14:10小时的光照：黑暗。实验大鼠于第12天经咽旁途径下丘脑切除；对照大鼠采用假垂体切除或不手术。由于两组完整的大鼠在血清黄体酮水平和妊娠持续时间上没有发现差异，因此它们将被视为一组，即完整的对照组。所有手术及采血均采用乙醚麻醉。垂体切除术的完整性是通过尸检时对垂体窝的检查和比较垂体窝的重量来确定的
Pregnant rats were either hypophysectomized or sham-hypophysectomized on day 12 (day 1: day of insemination) or unoperated on, and observed for the changes in the concentration of progesterone in peripheral serum and the time of parturition. Progesterone was measured by protein binding displacement; blood samples were collected serially in some rats and at autopsy in others between days 15 and 26. A large group of samples from rats in other experiments furnished values for the level on day 12. In both intact and hypophysectomized rats the mean serum progesterone level increased from 87.1 ng/ml on day 12 to about 130 ng/ml on day 15 and slowly fell to about 100 ng/ml on day 19. After day 19, the level continued to fall in the hypophysectomized rats at about the same rate as before, while in the intact rats, the rate of fall increased to about 10 times that present before day 19. All but 2 of 14 intact rats delivered on days 22 or 23; out of 15 hypophysectomized rats observed to term only 5 delivered, 3 of them on days 24 or 25. Of the other 10, 2 died on day 23, and 8 were killed or died between days 24 and 26. These findings, which indicated a strong but not absolute relationship between the fall in serum progesterone level and the onset of parturition, were interpreted to be discordant with the hypothesis (1) that luteinizing hormone (LH) is the essential luteotroohin during pregnancy in the rat. {Endocrinology 91: 1380, 1972) I HAS BEEN postulated that the essential luteotrophic stimulus during pregnancy in the rat is luteinizing hormone (LH) and that a deficiency of LH secretion after day 12 is specifically responsible (1) for the decline in progesterone secretion (2-8) which occurs prior to parturition in intact rats. This hypothesis, however, does not appear to be consistent with some of the effects of hypophysectomy in the pregnant rat. For example, although hypophysectomy before day 11 (day 1: day of insemination) practically always and promptly causes abortion, hypophysectomy on day 11 or 12 does not; in fact, pregnancy is not only maintained, but is usually prolonged beyond term and is frequently associated with abnormal and difficult labor (9-11). Treatment with progesterone also prolongs pregnancy (1,12,13) and it is possible, therefore, that the marked tendency for hypophysectomy to delay parturition is an expression of such an effect of progesterone; from the condition of the mammary glands, vaginas, and uteri, in fact, Alloiteau et al. (14) sugReceived April 7, 1972. 1 Supported by USPHS-NIH Training Grant HD00024, NIH Contract 70-2310, and Ford Foundation Training Grant 67-135. 2 Postdoctoral Trainee in Reproductive Biology (NIH TG HD-00024). gested that hypophysectomy causes a prolongation of progesterone secretion in the pregnant rat. These facts seemed to be sufficient reason to doubt the validity of Raj and Moudgal's hypothesis (1), since the hypophysectomized rat must surely secrete less LH than the intact one. The following experiment, therefore, was done. It was designed to compare the intact with the hypophysectomized pregnant rat for changes in the serum progesterone level between day 12 and term. Materials and Methods General. All rats (Sprague-Dawley strain; Holtzman Rat Company, Madison, Wisconsin) were bred in the laboratory, day 1 of pregnancy being considered as the day of insemination. They were maintained in plastic cages, with free access to Purina® Rat Chow and water, under a fixed lighting schedule of 14:10 hr of light:darkness. The experimental rats were hypophysectomized by the parapharyngeal route on day 12; control rats were either sham-hypophysectomized or were not operated on. Since no differences were found in either serum progesterone levels or duration of pregnancy between the two groups of intact rats they will henceforth be considered as one group, the intact controls. Ether was used as anesthesia for all operations and for the collection of blood samples. Completeness of hypophysectomy was determined by examination of the pituitary fossa at autopsy and by comparing the wt of the