Simultaneous measurements of plasma renin activity (PRA), aldosterone concentration and serum potassium were carried out in 27 hyperthyroid, 10 hypothyroid patients and 22 normal controls. In 16 hyperthyroid patients these analyses were done after 90mg propranolol administration for 6 to 12 days. In both hyper-and hypothyroid patients the studies were repeated after euthyroid achievement. Increased PRA (1.43± 0.14ng/ml/hr, m±S.E., on recumbent, 2.27±0.2ng/ml/hr on upright position) and aldosterone concentration (149±20pg/ml, 236±30pg/ml) were observed in hyperthyroidism. These values were both significantly high compared with normal controls (PRA: 0.29± 0.03, 0.74± 0.08, aldosterone: 67± 8, 110± 5). Increased PRA and aldosterone concentration in hyperthyroid patients were both significantly reduced after propranolol administration, but the extent of reduction was much greater in PRA than in aldosterone concentration. In hypothyroidism both PRA (0.23± 0.05, 0.27± 0.06) and aldosterone concentration (23± 3, 36± 8) were significantly low. Those increased and reduced PRA and aldosterone concentration were normalized after achievement of euthyroid states. Serum, potassium levels in these 3 groups were all within normal range and there was no significant difference among these groups. Changes of plasma aldosterone concentration were considered to be secondary to changes of PRA because of parallel changes of these parameters. Clinical significance of altered plasma aldosterone is discussed.

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The recent discovery of the stimulatory effect of gastrin or pancreozymin on the secretion of calcitonin in the pig has prompted us to study the gastrointestinal effect of calcitonin in rats.
The marked increase in the gastric acid and pepsin accumulation in rats in which the pylorus was ligated for 9hr was significantly inhibited by the prior treatment with 2 MRC U of purified porcine calcitonin.
This inhibitory effect of porcine calcitonin on the gastric acid and pepsin accumulation was dose dependent. Furthermore, the development of acute gastric ulcer in these rats was completely prevented by the s.c. administration of 2 MRC U of porcine calcitonin.

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Immature male rats (26-29 days and 34-36 days of age) and mature male rats (150-210 days of age) were electrically stimulated through chronically implanted electordes, and serum and pituitary concentrations of LH, FSH and prolactin were measured by radioimmunoassay. In mature male rats, stimulation of the medial basal prechiasmatic area (PVA), which showed a significant facilitatory effect on LH and prolactin release in the female, also induced an increase of serum LH and a relatively increased concentration of prolactin in serum. Stimulation of the medial preoptic area (MPO), medial and lateral parts of the amygdala (AMYG) induced a slight increase in serum concentration of LH. These results indicate that there is no sexual difference in the ability to induce LH release in the PVA and MPO. But the effect of AMYG stimulation is quite difficult to be explained, because it was observed in the present experiment that the stimulation in acute preparation had no effect on LH release. Dorsal hippocampus exerted an inhibitory effect on FSH secretion in immature rats. Immature male AMYG stimulation decreased pituitary concentrations of LH and FSH, in contrast to the immature female, which was indicative of the existence of sexual difference in the same area. All the brain areas examined except the PVA decreased serum concentration of prolactin following the stimulation in mature rats, but in immature rats all the areas examined showed no effect and rather facilitated it.

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Testosterone administration to castrated rats did not influence the total content and the composition of free amino acids in the blood plasma. No significant difference in the total content and the composition of free amino acids in the ventral prostate was observed between castrated and testosterone-treated castrated animals either.
Pro and Glu in free amino acid fraction and in tissue proteins were labeled after L-arginine-¹⁴C administration. Radioactivities in Pro and Glu of free amino acids and protein fractions from testosterone-treated castrated rats were higher than those from castrated rats. The tissue/plasma ratio of radioactivity and concentration of Pro and Glu in free amino acids fraction were high in ventral prostate, therefore, it was considered that some part of Pro and Glu was formed from Arg inside the tissue. Conversion rate of Arg to Pro and Glu was calculated, and it was found that the rate of Pro and Glu formation was increased 24hr after testosterone administration to castrated animals.
No influence of testosterone administration was observed on the utilization of guanido-¹⁴C after cleavage of arginine in rat ventral prostate.

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The intestinal absorption of parotin was investigated in Wistar rats by immunochemical techniques and radio-isotope iodine 125 tracer method combined with gel filtration. After administration via intestine parotin levels with time in both thoracic duct lymph and portal vein blood were estimated.
By immunochemical determination, percent of the dose absorbed in the lymph over 105 min upon administration of parotin with 5, 10, 20 and 50 mg doses per rat was 0.54, 0.30, 0.13 and 0.15 respectively. Portal vein blood level after administration of parotin (20mg/ml/rat) was only detectable in 90min serum sample, and was estimated to be 19.0μg/ml.
The ¹²⁵I-labelled parotin was injected via intestine and blood was collected in timed samples from the mesenteric vein. A radioactive peak was obtained at 60 min which corresponds to 0.96 % absorption of the initially administered radioactivity. When ¹²⁵I was administered, its radioactivity reached maximum at 20 min. Gel filtration patterns of the serum sample collected at 60 min showed that 69.3% of the activity was concentrated in a large molecular fraction, while with the 20 min serum sample obtained after injection of ¹²⁵I most of radioactivity was found in the second peak pattern, i. e. ¹²⁵I fraction. From these results, it was presumed that 0.66 % of parotin was absorbed as large molecules through the intestine.
The data obtained in the present experiment indicate that when administered via intestine parotin can be absorbed into thoracic duct lymph and portal vein blood stream with immunological reactivities and a large molecular size retained.

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Acute effects of ovarian steroids on the enlargement of a given set of follicles greater than 750μ in diameter were evaluated in the cycling rat under chlorpromazineblockade for ovulation by direct analysis of isolated follicles from fresh ovaries. A steady enlargement of newly generated follicles destined to ovulate was obviously delineated throughout the estrous cycle by newly devised assay. When ovulation was blocked by chlorpromazine hydrochloride (5mg/kg) given shortly before ovulatory release of gonadotropins, a successive linear increase in the follicular volume was kept at least by the expected day of estrus. Under these conditions, progesterone given at diestrus 2 caused a pronounced retardation of following follicular growth, the effective doses of which were almost comparable to those neccessary to prevent ovulation. Varying doses of estradiol ranging from 0.1 to 100μg given at diestrus 2 or daily dose of 10μg given at diestrus 2 and proestrus failed to cause any significant changes in average number of follicles and total follicular volume at the expected day of estrus. When given at estrus, however, it markedly suppressed the successive follicular growth. These results indicate that the exogenous estradiol itself is not able to alter the process of final course of follicular maturation when corpora lutea once degenerated, and that the suppression of follicular growth by estradiol given at estrus is probably due to the action of progesterone, the increased secretion of which is prolonged by the luteotropic action of the extrinsic estrogen.

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The changes in the serum prolactin levels during 8 ovulatory cycles, 3 anovulatory cycles, 3 clomiphene treated cycles, 4 premarin treated cycles and 2 cycles which had just become pregnant were measured by our heterologous radioimmunoassay.
Serum prolactin levels showed an increase in the ovulatory phase in 6 out of 8 ovulatory women and in the luteal phase in 5 out of 8 ovulatory women respectively.
No definite increase of serum prolactin in the ovulatory phase was observed in 2 out of 8 ovulatory and 3 anovulatory women. Oral administration of 1.25mg of premarin for 7, 10, 14 days slightly increased serum prolactin levels in 4 ovulatory women. Treatment with clomiphene increased serum prolactin in the ovulatory phase in 2 ovulatory women, but did not increase it in one woman who failed to ovulate.
Serum prolactin levels in 2 women who became pregnant during the investigation were determined. The rise of serum prolactin was observed in the ovulatory phase. But no marked increase of serum prolactin was demonstrated in the early pregnant luteal phase.
Our present results demonstrated ovulatory rise of serum prolactin. It is too early to conclude that human prolactin may have luteotrophic action in man.

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It was confirmed that the nuclear testosterone 5α-reductase was attached to membrane fraction as observed by Moore and Wilson (1972) in rat ventral prostate. Testosterone 5α-reductase of the nuclear membrane fraction was partially solubilized by phospholipase A, and overall 20 fold purification was attained. Optimum pH, pyridine nucleotide requirement and time course of the reaction of the solubilized enzyme were examined.

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A gonadotropin-inhibiting substance, which is assumed to be secreted by the pineal, is significantly reduced in urine following the removal of the pituitary in rats. The experiment was performed to investigate whether the reduced excretion of the gonadotropin-inhibiting substance in hypophysectomized rats is restored by administration of gonadotropins and whether the excretion of the inhibitor is influenced by administration of gonadotropins in intact animals. Administration of gonadotropins was effective in partial restoration of the reduced excretion of the inhibitor in the hypophysectomized rats. Treatment of gonadotropins in intact rats had no effect on the excretion of the inhibitor. These findings suggest that gonadotropins play some role in the production of the inhibitor.

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Using a purified human chorionic TSH (hCTSH), which was extracted from the term placenta, the authors developed a method of radioimmunoassay of hCTSH and estimated serum hCTSH in normal or molar pregnancy along with estimations of pituitary TSH (hPTSH), total thyroxine (T₄) and effective thyroxine ratio (ETR).
As a result, hPTSH level remained within the non-pregnant range throughout the whole course of pregnancy, but hCTSH tended to increase gradually toward the terminal stage of pregnancy. T₄ and ETR remained within the non-pregnant range but the former showed gradual increase toward the term. In molar pregnancy, the hPTSH level was normal but the level of hCTSH was markedly high. The same applied to T4 and ETR. After molar delivery hCTSH disappeared rapidly accompanied with gradual decrease in T₄ and ETR.

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The ovariectomized rats injected with high molecular RNA extracted from the estrogenised rat uterus showed increased incorporation of ³H-thymidine and other morphological changes of the endometrium, which were similar to those observed in the rats treated with estradiol-17β.
Furthermore, the ovum implantation could be induced by injection of the high molecular RNA in progesterone-treated ovariectomized pregnant rats.
These findings suggest that RNA representing an estrogen message can replace estrogen in the induction of implantation in delayed implantation of rats.

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In four patients with euthyroid Graves' disease, serum T₃ concentration and TRH response were tested. All four patients showed T₃ concentration within normal range, albeit representing TRH-refractoriness. The results suggest the possibility that thyroid hormone concentration is not a sole determinant of TRH-responsiveness in Graves' disease, implying currently undetermined pathologic process underlying the abnormality.

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The testes of the adult medaka, Oryzias latipes, reared in natural conditions of light and temperature, were examined histochemically for the occurrence of Δ5-3β-hydroxysteroid dehydrogenase (3β-HSD) in various periods of the annual reproductive cycle. In the testes of the fish, interstitial cells were present as clusters of varying numbers of cells, showing denser distribution along the region where seminal tubules conjoined with efferent ducts. In the period of active breeding of the fish, the testes exhibited an obvious histochemical response for 3β-HSD which was localized exclusively in the interstitial cells. During the sexually inactive period, the histochemical activity decreased in intensity as well as in number of responding cells, and was eventually indetectable in the testes until it reappeared in interstitial cells concomitantly with recovery of the spermatogenetic activity in the next breeding period. These results were not consistent with the histochemical observations made by Gresik et al.(1973), who could not reveal the histochemical activity of 3β-HSD in the testis of the medaka which were maintained continuously in a breeding state.

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Synthetic somatotropin-release inhibiting factor (10ng/ml) decreased significantly basal level of cyclic AMP concentration and showed marginal inhibition of GH release in rat anterior pituitary gland in vitro. Higher dose of synthetic somatotropinrelease inhibiting factor was needed to produce significant inhibition of GH release from the gland. Results obtained in the experiments suggest that somatotropin-release inhibiting factor as well as hypothalamic releasing hormones may act through adenyl cyclase-cyclic AMP system in the anterior pituitary gland.

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