Makimura N, Kato K, Nagata I
Nihon Sanka Fujinka Gakkai Zasshi. 1982 Feb;34(2):153-9.
In order to clarify the onset mechanism of labor, we studied the prostaglandin production in human placenta tissues of different stage using a superfusion technique. 1) The placenta obtained at Cesarean section before the onset of labor (A): (1) In the control, the production of prostaglandins was not distinctly changed. (2) Administration of arachidonic acid increased gradually the production of PGs. PGs production showed the maximum values at 50-60 minutes fraction of the superfusion. Throughout the experiment, PG production became vigorously active. (3) Administration of oxytocin increased the production of PGs, too, in particular PGE2 and PGF2 alpha. 2) The placenta obtained at Cesarean section during delivery (B): (1) In the control, the production of PGs was not distinctly changed. (2) Administration of arachidonic acid increased the production of PGE2 and PGF2 alpha, but the production of PGs was lower as compared with (A). PGE1 did not change. (3) Oxytocin had no effect on the production of PGE1 and PGE2, but the production of PGF2 alpha showed the maximum values at 50-60 minutes fraction. 3) The delivered placenta (C): (1) In the control, the production of PGs was not distinctly changed. (2) Administration of arachidonic acid increased the production of PGs. (3) Oxytocin had no effect on the production of PGs. On the basis of these data, it may be appropriate to conclude as follows: The enzyme which has a high ability to produce PGs exists in the placenta before the onset of labor. But the enzyme keeps the resting condition by the some inhibiting factor of PG production. During delivery, the PG production by the placenta fell. This result means that the strong ability of the production of PGs by the placenta at this stage is not necessary. After the delivery, the production of PGs by the delivered placenta is unnecessary. It is substantiated Kato's theory which PGE is primarily involved in the onset of labor that the production ability of PGE was recognized only in the placenta of before the onset of labor. It is interesting that administration of oxytocin increased the production of PGF2 alpha and they are similar for the contraction-substance of uterus.
为了阐明分娩的起始机制，我们使用超灌注技术研究了不同阶段人胎盘组织中前列腺素的产生。1）分娩发动前剖宫产获取的胎盘（A）：（1）在对照实验中，前列腺素的产生没有明显变化。（2）给予花生四烯酸后，前列腺素的产生逐渐增加。前列腺素的产生在超灌注的50 - 60分钟时段达到最大值。在整个实验过程中，前列腺素的产生变得非常活跃。（3）给予催产素也增加了前列腺素的产生，尤其是前列腺素E2和前列腺素F2α。2）分娩期间剖宫产获取的胎盘（B）：（1）在对照实验中，前列腺素的产生没有明显变化。（2）给予花生四烯酸增加了前列腺素E2和前列腺素F2α的产生，但与（A）相比，前列腺素的产生较低。前列腺素E1没有变化。（3）催产素对前列腺素E1和前列腺素E2的产生没有影响，但前列腺素F2α的产生在50 - 60分钟时段达到最大值。3）娩出的胎盘（C）：（1）在对照实验中，前列腺素的产生没有明显变化。（2）给予花生四烯酸增加了前列腺素的产生。（3）催产素对前列腺素的产生没有影响。基于这些数据，可能可以得出如下结论：在分娩发动前，胎盘中存在具有高前列腺素产生能力的酶。但该酶通过某种前列腺素产生抑制因子保持静止状态。在分娩期间，胎盘产生的前列腺素下降。这一结果意味着在此阶段胎盘产生前列腺素的强大能力并非必要。分娩后，娩出胎盘产生前列腺素是不必要的。这证实了加藤的理论，即前列腺素E主要参与分娩发动，因为仅在分娩发动前的胎盘中才识别出前列腺素E的产生能力。有趣的是，给予催产素增加了前列腺素F2α的产生，并且它们与子宫收缩物质相似。
