In 1861, Ito and Higashi discovered in human placentae a biological active protein which had prolactin like activity with a pigeon crop sac assay. In 1962, Josimovich and MacLaren, using an immunodiffusion gel technique, demonstrated that the serum of pregnant women contained a lactogenic protein which had immunologically partial identity with pituitary growth hormone. They named this protein, “human placental lactogen (HPL).”
Kaplan and Grumbach isolated this protein also and have suggested “chorionic growth hormone prolactin (CGP)” as its name.
In this paper the first term or HPL (Human Chorionic Somatomammotropin) will be used as the name of this protein. Several investigators have studied the chemical and biological character, and dynamic behavior of HPL during pregnancy. But the specific biological character of this protein has not yet been clarified.
It is the purpose of this paper to report the studies on the systematic anrd detailed analysis of biological charactesitics of this protein hormone.
HPL was extracted by modified Friesen's method from term placentae and was purified by gel filtration, ion exchange cellulose chromatography and DEAE-Sephadex A50 chromatography. The purified HPL (HPL-Kobe) developed a single band by 7% polyacrylamide disc electrophoresis and its molecular weight was about 20,000. The immunological character of this HPL showed evidence of partial identity with human growth hormone but antigenicity was not identical with human chorionic gonadotropin. It showed no cross-reaction with prolactin and human sera.
Crude HPL mobilized the FFA and blood glucose in serum in vivo and in the incubation medium in vitro and it also promoted the increase of glucose and insulin, and accelerated the activitities of hormone sensitive lipase (HSL) and lipoprotein lipase (LPL) in epididymal fat pads of rats of Wistar strain.
The biological character was also studied for its lipolytic action on rat epididymal fat pad in vitro. The addition of epinephrine (10 μg per ml), caffeine (0.01 M per ml), cyclic 3', 5' AMP (Iml per ml) or single HPL (30 μg per ml) to the incubation medium released nearly equal amounts of FFA. But combination of HPL (30 μg per ml and 3 μg per ml) with caffeine (0.01 M per ml) gave an enhanced release of FFA and activated HSL and LPL also. When adrenergic blockers (Dibenamine 3 μg per ml and Inderal 30 μg per ml) were added in combination with HPL, HSL and LPL activities were markedly lowered, but release of FFA was not so remarkably influenced. In this experiment with castrated male rats injected with estrogen 1 μg per 100 g body weight for 4 days or progesterone 1 mg per loog body weight for 4 days, the release of FFA was more remarkably accelerated by HPL administration in progesterone sensitized fat pad in vitro but estrogen had no influence. Injection of reserpine (100 μg per 100 g) had no effect on the release of FFA. When pregnant rats were injected with HPL, FFA, insulin and glucose markedly promoted to increase in the maternal blood and at the same time FFA in fetal blood increased significantly, and insulin and glucose remained the same. The above-mentioned findings indicate that HPL acts on maternal tissue to abtive adenyl cyclase and accelerate lipolysis via cyclic AMP.
From these experimental results, the auther may be able to conclude that human placental lactogen is a very important endocrine factor which influences the metabolism of fat and carbohydrate in the “feto-placental maternal system, ” especially promotes the fetal growth via peculiar changes of maternal metabolism during pregnancy.

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Urinary 17-deoxycorticosteroids were determined in normal adult females during a menstrual cycle and in the dynamic test which was performed by stimulation of ovary with HCG under suppression of adrenal with dexamethazone. They were also determined in patients with various endocrine disorders.
7 fractions of urinary 17-deoxycorticosteroid were simultaneously determined by the method already reported. Pregnanediol and 17-hydroxycorticosteroid were also determined.
1) Determinations of 17-deoxycorticosteroid in the secretory phase of normal menstrual cycle showed a slightly higher level than those in the proliferative phase, but not significant.
2) Successive determinations during the entire menstrual cycle showed no correlation between 17-deoxycorticosteroid and 17-hydroxycorticosteroid nor pregnanediol.
3) In the dynamic test, 17-deoxycorticosteroid decreased by suppression of adrenal with dexamethazone and slightly increased by stimulation of ovary with HCG. On the other hand, 17-hydroxycorticosteroid decreased remarkably by adrenal suppression but did not increase by ovarian stimulation, and pregnanediol was not changed by adrenal suppression but increased remarkably by ovarian stimulation.
4) In patients with Cushing's syndrome, 17-deoxycorticosteroid showed lower level than normal mean value and 17-hydroxycorticosteroid was on a very high level.
5) Determinations of other endocrine disorders are shown in Table 3 and Fig. 7.
6) It might be concluded that 17-deoxycorticosteroid is regulated independently from levels of both pregnanediol and 17-hydroxycorticosteroid. And therefore, 17-deoxycorticosteroid could be estimated without considering the function of the ovary.

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In order to investigate the mechanism of estrogen production and its control by HCG in the term chorionic tissue, the following experiments were conducted.
First of all, estrogens contained in the term chorionic tissue were extracted and purified by the method of Brown-Kanbegawa, and fractionated by the method of Stimmel-Kanbegawa, and colored by Kober's test, and finally determined quantitatively ; estrone was 25.7 μg, and estradinl 67.8 μg and estriol 243.7 μg per kg of wet weight. When corrected by the recovery rate, they gave the counts of 63.6 μg, 130.9 μg. and 316.5 μg, respectively.
Secondly, the minced chorionic tissue was incubated together with various steroids, and the produced estrogens were estimated in the same way. There was no conversion to estrone observed in the group of C₂₁-steroids such as pregnenolone and progesterone, while the group of C₁₉-steroids such as dehydroepiandrosterone (DHA), Δ4-androstenedione (Δ4 A) and testosterone (Test.) showed aromatization at a high rate, and further, most.of them were converted into estrone.
The third experiment aimed at examination of influences caused by mixing various coenzymes including HCG in vitro. ³H-DHA, ³H-Δ4A and ³H-Test. were employed as substrates and incubated similarly. The produced estrogens, especially estrone, were extracted, purified and fractionated in the same way as mentioned above and passed through a thin layer-chromatography to be estimated for changes in their radioactivity with the liquid scintillation counter. NADPH proved to have an extremely simulative action for producing estrone, which came up to a level as high as 20 times that of maximum. NAD also promoted the production to a mild extent, while the effect of 3' 5' AMP was uncertain. HCG added to 10 ml of medium at the rate of 50-100 IU increased the production of estrone by 80% on the average. This stimulative action was not observed with an extremely decreased or increased density. HCG contained in the urine of pregnant women at term showed a stimulative action of +72% when added at the rate of 50 IU, and a suppressing action of -22% When added at the rate of 10,000 IU. Further, the 800 × G and 10,000 × G suspernatants of the chorionic tissue-hamogenote as well as the chorionic tissue of anencephalic monsters were almost similarly favored with an increased production of estrogens by HCG.
It was found from these results that HCG has an important function in controlling the mechanism of estrogen-production in the chorionic tissue.

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