As already reported, the activities of α-L-glutamyl β-naphthylamidase, Lleucyl β-naphthylamidase, and L-Ieucinamide hydrolyzing enzyme (leucine aminopeptidase) in rat serum were changed markedly by the injection of various doses of parathormone. The effect of parathormone on the enzyme activities for the hydrolysis of other amino acid β-naphthylamides in serum was reported in this communication. Naphthylamides of 6 different amino acids were used as substrates to measure the activities. The activities in rat serum which hydrolyzed β-naphthviamides of alanine, methionine, norleucine, and phenylalanine were not changed significantly by an injection of 1200 U.S.P. parathyroid units/100g body weight, and 86, 74, 90, or 88% of controls, respectively. However, the enzyme activity for the hydrolysis of arginyl or lysyl β-naphthylamide (aminopeptidase B) was decreased to 37% or 47 % of controls by the injection of 1200 units of parathormone.

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The growth, the anterior pituitary weight, and the anterior pituitary growth hormone (GH) content of C3H/He and C57BL/6 strains of mice were investigated during 12-120 days of age in the male and 30-90 days of age in the female. The pituitary GH content was measured by disc electrophoresis. The pattern of growth and the increasing rate of body weight were similar in either strain, whereas the body weight of C3H/He was always greater than that of C57BL/6 in both sexes. The whole pituitary weight increased with age until 40-60 days and became plateau thereafter in the male of both strains and the C57BL/6 female. On the other hand, the pituitary weight of the C3H/He female continued to increase until the 90th day. Although the pituitary weights were greater in C3H/He than in C57BL/6 until the 60th and 90th days of age in both sexes the pattern of its change was little different according to the strains. The variation of the relative pituitary weight per 10g body was not so remarkable with age in both strains and sexes. In both strains, the total GH content and the relative GH content per 10g body changed in a similar pattern with age, which increased until 50-60 days of age and became plateau or inclined to decrease a little after that in the male, while they continued to increase until the 90th day in the female. The total GH content in C3H/He was significantly higher than that in C57BL/6 in either sex. The relative GH content per 10g body showed no difference between strains in the male, but it was higher in C3H/He than in C57BL/6 in the female. In C3H/He, the female excelled the male not only in the total GH content but also in the GH content per 10g body on the 60th and 90th days. On the other hand, Iittie sex-differences were observed in these areas in C57BL/6. The GH content per mg pituitary showed no noticeable variations with age, strain and sex. The significance of these findings was discussed.

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The islets of Langerhans in guinea pigs with steroid-induced diabetes (by injecting 5mg of cortisol twice daily) were studied histologically and histochemically at various time intervals. The islets in those animals marked hypertrophy with hyperplasia. Hydropic degeneration and glycogen infiltration were also observed in the beta cells in various degrees. The alpha cells of the animals with prolonged severe diabetes also showed degranulation and glycogen infiltration, which had not yet been reported and represented unique findings in steroid-induced diabetes. Histochemical studies showed a definite increase of glucose-6-phosphatase activity after 3 days of cortisol treatment. The activities of glucose-6-phosphate dehydrogenase and lactic dehydrogenase increased in both alpha and beta cells. In the early stage of diabetes acid phosphatase activity was either normal or slightly increased, but later decreased in both alpha and beta cells. These altered enzymatic activities returned to normal one week after cessation of steroid treatment. Several other enzymes examined histochemically showed no significant changes. The histochemical findings in the alpha and beta cells in this experiment suggest a new interpretation of the functional correlation between the two types of cells. The significance of these enzymes and their possible role in the functional activity of the islet cells are discussed.

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The developmental process of adrenal function in maturing rats was observed by histo-and biochemical procedures. The activity of Δ⁵-3β-OH steroid dehydrogenase capable of oxidizing Δ⁵-3β-OH steroids to Δ⁴-3-keto steroids, was bio-and histochemically investigated. The distribution of DPNH-diaphorase, glucose-6-phosphate dehydrogenase, succinic dehydrogenase, acid phosphatase and lipid was determined by histochemical methods. The body and adrenal weight were markedly increased between 20 and 40 days of age. At the same time, Δ⁵-3β-OH steroid dehydrogenase activity was gradually increased in the fascicular and reticular zones. This enzyme activity in females was higher than in males at the age of 30 days. The lipid free subglomerular zone, a transitional zone, disappeared at 40 days of age only in females. Histochemically, glucose-6-phosphate dehydrogenase activity was distributed in a similar way to Δ⁵-3β-OH steroid dehydrogenase except in the intramedullary cortical cells at all ages; this finding might indicate a close relationship between the two enzymes in steroidogenesis. Though the intramedullary cortical cells (Van Dorp and Deane, 1950) were morphologically similar to the reticular zone, the function might be different, since both were different in the distribution of enzymes and lipid. The distribution of succinic dehydrogenase activity paralleled that of acid phosphatase in all age groups. The distribution of DPNH-diaphorase activity was characteristic in its high concentration in the glomerular zone. While the layer highest in succinic dehydrogenase activity gradually moved to the inner part of the fascicular zone with maturation of animals, that in glucose-6-phosphate dehydrogenase and Δ⁵-3β-OH steroid dehydrogenase activities shifted to the outer part and the layer rich in lipid as well.

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Healthy adult male rats were given test diets containing varying amount of calcium from 0.01 to 10% for 14 days. The resultant changes of parafollicular cells of the thyroids of these rats were histologically investigated and their number was counted, along with the bioassay of thyrocalcitonin. The parafollicular cells were divided into the light and dark cells. Upon feeding rats with a diet containing a moderate amount of calcium, 1.0 or 2.0%, dark cells proliferated and formed anastomosing cords surrounding the follicles, and light cells decreased in number. In rats given a diet containing a high or low calcium content, light cells increased, but dark cells disappeared. A striking increase of light cells was found upon the use of a diet containing 10 % calcium. The bioassay of thyrocalcitonin only from the thyroids of these rats revealed the hypocalcemic effect. The number of parafollicular cells was not necessarily in parallel with the present bioassay data.

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The pituitary anterior lobes of male rats castrated at the age of 45 days were investigated histologically and histometrically at various time-intervals of between 10 and 300 days after operation. The total number of the cells of the glands was counted on the serial sections made of the glands stained with PAS-iron hematoxylin, aldehyde thionin-PAS-luxol fast blue, alcian blue-orange G and azan. There was a tendency that thyrotrophs began to decrease in number between the 90th and 300th day after operation. Histometrically, the hypertrophied gonadotrophs, whether or not they became signet-ring cells, were found to increase gradually in number. The cell-height of thyroid follicles increased about twice as much as normal within 60 to 300 days after castration. This may suggest a chronic hyperfunction of the thyroid. The stimulated sign of the thyroid and a concurrent loss of thyrotrophs in the hypophysis are in contradistinction to a view that the thyrotroph is the only cell producing TSH. The flexible interpretation is, therefore, necessary when a distinction between thyrotrophs and gonadotrophs is to be made. In our observation there was some evidence which favoured the necessity of such an interpretation. In short, it was found that the thyrotrophs and gonadotrophs were not essentially independent. They seemed to be transient forms of a cell at different stages of its transformation into a basophil.

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The mammary growth following the estrogen injection into the ovariectomized immature mice of DS colony was studied using the ductal extension of the third thoracic mammary gland as a criterion. A rapid growth of the gland was achieved by the daily subcutaneous application of estradiol as little as 0.03μg a day for 9days after ovariectomy. A variety of steroids were subcutaneously injected daily along with the estrogen treatment for 9days. 5α-Androstan-17β-ol-3-one and its 2-substituents, dromostanolone propionate, oxymetholone and 17α-methyl dromostanolone, strongly inhibited the estrogen-stimulated mammary duct growth. The reduction of 3-one and/or oxidation of 17β-ol in 5α-androstan-17β-ol-3-one resulted in marked decrease of the inhibitory effect. The introduction of double bond at ring A slightly modified the activity of the parent androstane. On the other hand, potent estrogen antagonists on the uterus, such as 19-nortestosterone, norethisteron, progesterone and MER-25 were almost inactive. These results indicate that there is no direct correlation between the mammary growth inhibiting ability and the androgenic activity or anti-uterotropic activity of a steroid. The biological significance of these estrogen-steroid interactions on the mammary gland development was discussed.

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It is a well known conception that the hypothalamo-hypophysio-ovarian system constitutes an axis on gonadal function. Recently, it was found that the limbic system played an important role on the mechanism of ovulation. In order to clarify the co-relation between the hypothalamus and the limbic system, the electrical activities of the brain of 20 ovariectomized mature New Zealand white rabbits were examined. Two different EEG phenomena were applied for this investigation, i.e., (1) EEG afterreaction on the hypothalamus and (2) after-discharge on the limbic system. The alteration of brain activity was indicated by the electrical threshold, duration and latency of these two EEG phenomena. The results were as follows;(1) The activities of these areas revealed typical biphasic changes-excitatory and then depressed-when 10 mg of either progesterone or retro-progesterone were injected subcutaneously. The inhibitory effects on the hippocampus was, however, not evident.(2) By intravenous injection of 0.08mg of estradiol benzoate, hypothalamic activity was depressed slightly and briefly. The threshold of the amygdaloid discharge remained unchanged, while that of the hippocampus, however, was markedly depressed.(3) Three mg of Compound F6066, non-steroidal estrogenic substance, showed an effect quite similar to that of estrogen.(4) Bitemporal indirect pulse stimulation, which is applied for clinical induction of ovulation, revealed excitatory effects for one hr. and a half on the hypothalamus as well as on the limbic system.

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Glycogenolysis in the anterior pituitary lobes of the rat was examined following intrapituitary microinjection of varying amounts of a purified pig hypothalamic CRF. The pituitary glycogen showed a significant decrease 20 mins. after direct injection of crude acetic acid extracts of the median eminence or a purified hypothalamic CRF. A greater depletion of the pituitary glycogen was obtained with increasing amount of CRF injected. It was concluded that glycogenolysis is involved in the enhanced ACTH secretion induced by CRF. Furthermore, from the analysis of the correlation between ACTH release and glycogen decrement, it was suggested that secretion of ACTH was biphasic, i.e., glycogenolysis-dependent and-independent.

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