In male mice which had been given 15 daily injections of estradiol-17β(E) from the day of birth, 20μg for the first 10 days and 40μg for the following 5 days, spermatogenesis was permanently inhibited. Both the seminiferous epithelium and the interstitial tissue of the testes were highly deranged in half the number of the animals at 60 days of age. If testosterone propionate (TP), 4-40μg for the first 10 days and 8-80μg for the following 5 days, was injected simultaneously with E, active spermatogenesis was going on in the testes when examined at 60 days, although the testes were smaller than those in the oil controls. The epithelium of the seminal vesicles and ventral prostates was stimulated by endogenous androgen in the mice given E plus TP.

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Daily injections of gonadotropins (PMS, HCG or PMS-HCG) for 15 days from the day of birth, 1 I.U. for the first 10 days and 2 I.U. for the following 5 days, resulted in a hypertrophy of interstitial cells in the testes of mice at 15 days of age. The seminal vesicles were highly stimulated by endogenous androgen in these animals. In the testes of the 60-day-old males which had been given daily injections of estradiol-17β(E) for 15 postnatal days, 20μg for the first 10 days and 40μg for the next 5 days, spermatogenesis was arrested or the seminiferous epithelium was severely damaged. In contrast, the testes of those receiving neonatal injections of E and PMS, E and HCG, and E and PMS-HCG were undergoing active spermatogenesis, showing no damages to the seminiferous epithelium. These findings appear to indicate that neonatally injected estrogen is antagonized by androgen secreted from the testes in response to exogenous gonadotropins and, as a consequence, that the gonadotropin secretion from the anterior hypophysis is not affected.

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Influence of the fornix section on the biosynthesis of ovarian steroids, which was indicated by the transfer rates of ¹⁴C from ¹⁴C-1-acetate into progesterone, 20α-hydroxypregn-4-en-3-one (20α-OH-P) and estrogen (estradiol and estrone) in the ovarian homogenates incubated for 1 h, was studied in the female mature New Zealand white rabbits (2.5-3.0 kg). The animals served the experiment at least 3 to 4 weeks after the operation of sectioning the fornix. The results were as follows: 1) The biosynthesis of progesterone, 20α-OH-P and estrogen decreased markedly (approximately 50%) compared to the nonoperated controls, while the ovarian weight did not change. 2) The estrogen primed animals with the fornix section did copulate but not ovulate. However the biosynthesis of progesterone, 20α-OH and estrogen increased by approximately 100%, indicating the release of ovulating hormone.
These results indicate that the elimination of the hippocampal influence to the hypothalamus, in the long-term experiment, markedly reduces the pituitary-ovarian activity.

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The response of GH, TSH, FSH and LH secretion to L-dopa administration was investigated in 14 normal subjects and 9 patients with Parkinson's disease in order to evaluate this catecholamine precursor as a pituitary function test. The oral administration of 0.5 or 1.0g L-dopa stimulated GH release in 6 out of 10 normal individuals and 4 out of 6 patients. The peak levels of plasma GH were observed between the periods of 30-90 min after L-dopa, and the peak values of plasma GH were 8.9±1.9ng/ml in normal subjects and 8.1±2.3 in the patients, but the peak GH levels were less than those observed in the cases of arginine load or insulin-induced hypoglycemia. The remaining 6 subjects and 5 cases (2 normals and 3 patients) who received a single intravenous administration of 50mg L-dopa showed minimal response to L-dopa. Blood glucose, plasma TSH, FSH, LH and insulin levels did not change significantly after the L-dopa administration in all cases, including the subjects in whom plasma GH levels were elevated by L-dopa. Three normal females with normal menstrual cycle were examined in their follicular and luteal phases, but showed no response in plasma FSH and LH secretion to L-dopa in either phase.
These results indicate that L-dopa has a relatively great potential as a provocative agent for stimulating GH release but only a limiting merit as a pituitary function test because of less reliability than arginine or insulin-induced hypoglycemia. The L-dopa has no significant effect on TSH, FSH and LH secretion in man.

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Octadecapeptide β-Ala¹, Orn¹⁵-(1-18) ACTH-NH₂ (I) or β-Ala¹, D-Phe₇, Orn¹⁵-(1-18) ACTH-NH₂ (II) was incubated with isolated rat adrenal cells at 38°C for 1 hr. The quantities of corticosterone and 3', 5'-cyclic AMP produced were determined simultaneously. In the isolated adrenal cell system, the maximal steroidogenic responses induced by these two peptides were elicited with only a slight increase of 3', 5'-cyclic AMP level and higher concentrations of ACTHs were needed to evoke the maximal 3', 5'-cyclic AMP levels.
I-induced increases in corticosterone production and in 3', 5'-cyclic AMP levels were not altered by the presence of an equimolar amount of II. This ffnding is contrary to that obtained with a cell-free system of rat adrenals, in which the activation of adenylate cyclase induced by I or natural ACTH was inhibited by the simultaneous addition of II. The concentration-response curves for I with respect to steroidogenesis and increase in 3', 5'-cyclic AMP level were compared with those for II. The curves for II were respectively parallel to those for I but were shifted to higher concentration along the logconcentration axis. A theoretical consideration on the kinetics suggests that the isolated adrenal cells may have spare receptors for ACTH, and that the slight difference in affinity between I and II would be emphasized and the inhibitory effect of II reduced.

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An attempt was made to investigate a role of the brain on release of gonadotropin responsible for the events of proestrus and estrus in the 4-day cyclic rats. Rats were acutely deafferented at the level of anterior commissure (AC) with three kinds of the L-shaped knives at the different time of day, and autopsied to examine the uterine distension and ovulation on the days of expected proestrus or estrus. Serum and pituitary level of LH, FSH and prolactin in the deafferented rats were measured by radioimmunoassay. The results are as follows: 1) With an L-shaped knife of 2.5 mm of the horizontal blade (knife A) the fornix (Fx) and the stria terminalis (ST) were interrupted and simultaneously the tract of diagonal bundle of Broca (TDB), the bed nucleus of stria terminalis (BST), the nucleus of accumbens (ACC), the nucleus of anterior commissure (NAC) and parolfactory area were commonly damaged. The deafferentation at 20:00 on the day of diestrus I prevented vaginal cornification, uterine distension and ovulation on the expected estrous day. Full cornification was observed in all examined rats with transection after 10:00 on the day of diestrus II, while uterine distension was not observed in the rats with transection before 20:00 on the same day. None of rats bearing the transection ovulated on the day of estrus, even the transection was performed at 8:00 on the day of proestrus. 2) With an L-shaped knife of 1.4mm of the horizontal blade (knife B) the Fx were interrupted and the BAC and the TDB were commonly damaged, however, the ST, the BST and the ACC were only partially damaged. Most of results following to the neural transection with knife B were similar to those observed with knife A except for ovulation being observed in the rats transected at 8:00 on the day of proestrus. However, transection at the mid-thalamus (knife placed at 2mm caudal to the AC) did not interfere any normal cyclic changes. 3) Estrogen injection into the rats transected with knife B at 20:00 on the day of diestrus II resulted in inducing ovulation, while with knife A did not. 4) Transection either Fx or medial cortico-hypothalamic tract (CHT) with an L-shaped knife of 1.0 mm of the horizontal blade (knife C) on the day of diestrus I partially prevented the occurrence of events of proestrus and estrus. 5) Transection of the septal complex with knife B at 20:00 on the day of diestrus I prevented a rise of pituitary LH, pituitary prolactin and serum prolactin, which used to be observed in normal proestrus. Both Fx and CHT transection resulted in an increase of pituitary FSH. From the ovariectomy experiment the ovary of the our colony's rats must be in situ at 15:00 for vaginal cornification and at 24:00 for uterine distension. Thus, following facts are suggested 1) the septal complex or higher brain such as the limbic structure may be involved in the release of gonadotropin responsible for the events of proestrus and estrus, 2) timing of release of gonadotropin (folliculotropin) might occur preceding to the ovarian changes and it must start sometime before early morning of diestrus II.

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Electron microscopic study was made on rat anterior pituitaries in an attempt to clarify the causal mechanism of “loss of acidophils” which could be detected with the light microscope following thyroidectomy. In the advancing days after thyroidectomy, the acidophils (somatotrophs) were gradually deprived of their large granules whose diameter was about 350mμ. There was evidence in vivo for the first time that there were some acidophils containing only the small granules, about 130mμ in diameter, after the 7th postoperative day. This clearly showed the simultaneous existence of two different sizes of granules in the same acidophils. As time elapsed, the large granules dispersed from the acidophils. After the 30th day these acidophils began to adjust their shape into the polygonal cells. Eventually, the acidophils completely lacking granules of either size occassionally appeared on the 90th and 200th days. Thus thyroidectomy had a strong influence to release the large granules, whereas an influence to release the small ones was not remarkable. The replacement injection of thyroxine into the thyroidectomized rats efficaciously reproduced the large granules which were generally considered to be responsible for GH storage. The repeated administrations of dexamethasone to the thyroidectomized rats resulted in the increase in number of small granules that were thought by us to be the storage carriers of ACTH. On the other hand, this compound alleviated loss of large granules following thyroidectomy. The final fate of acidophils after thyro cectomy was, however, still vague because of the equivocal distinguishment of these degranulated acidophils from the immature basophils. Thus, the “loss of acidophils” may not mean the intrinsic disappearance of the cells themselves, but represent a transient loss of the large dense granules in the remaining acidophils.

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The levels of plasma ACTH and GH were simultaneously measured in normal subjects every 30 min for 4 nr after an oral administration of metyrapone, either 1.0g or 1.5g. Both doses of metyrapone caused a significant decrease in plasma cortisol levels 90min later, when the mean values of plasma cortisol levels were not significantly different between both groups. An administration of 1.0g of metyrapone raised plasma ACTH levels in 2 out of 6 subjects within 90min, while an increase in plasma GH levels of 5.0ng/ml above the base line levels was observed in 2 subjects. In one of the subjects in whom the levels of plasma GH increased, plasma GH peak was preceded by that of plasma ACTH, but no rise in plasma ACTH levels was observed in another subject. When 1.5g of metyrapone was given, plasma ACTH levels increased in all 6 subjects. The response of plasma ACTH was quite different in each individual and there appeared one or two peaks within 240 min. The mean value of plasma ACTH was 69±17 pg/ml at 0 time and increased to 165±18 pg/ml at 60min (p<0.01 vs 0 time). An increment in plasma GH levels was observed in 5 out of 6 subjects. The mean peak value was reached at 90min and the difference between the values at 0 and 90 min was significant. There was also no correlation between the secretion of ACTH and that of GH. These results may indicate that a higher dose of metyrapone causes both ACTH and GH secretions within a short period not by a negative feedback mechanism of cortisol but presumably by acting directly on the pituitary and/or on the hypothalamus as a nonspecific stimulus.

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Male and female fetal rats were gonadectomized in utero on the 20th day of gestation. Two days after the operation, the pituitaries were observed histologically in order to examine the changes of the population of basophilic cells. The gonadectomy of a male fetus caused a significant increase in the per cent of basophilic cells, whereas that of a female fetus induced no significant change. Since the increase in the relative number of basophilic cells following gonadectomy has already been accepted to be intimately related to the increased production of gonadotrophic hormones, the present results strongly suggest that the feedback mechanism between the pituitary and the gonad is already operated before birth in males but not in females. There is a definite sex difference in development of the pituitary-gonadal axis during the fetal life.

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Na-K-activated adenosinetriphosphatase (Na-K-ATPase) has been implicated in the active excretion of sodium ions by the gill of teleosts living in sea water. In the eel, Anguilla japonica, the activity of this enzyme increased markedly one week after transfer from fresh water to sea water. Hypophysectomy resulted in a reduction of this adaptive increase and the impairment was restored by cortisol treatment. Cortisol injection into intact freshwater eels induced a rise in the branchial Na-K-ATPase activity. When seawater-adapted eels were returned to fresh water, the enzyme activity decreased gradually. Prolactin injection into hypophysectomized eels promoted this decrease. Injection of prolactin into intact or hypophysectomized seawater eels, however, failed to affect the enzyme activity. The significance of these results was discussed in relation to possible hormonal influences on seawater adaptation of the eel.

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The effect of differing crossreactivities of antiglucagon sera with pancreatic and gut glucagon on the content of immunoreactive glucagon (IRG) in plasma has been investigated.
Two types of antisera employed in the study gave identical dilution curves for pancreatic glucagon, but different ones for gut glucagon. The mean value of IRG of seven plasma samples determined using antiserum less reactive to gut glucagon was 0.57±0.19 mμg/ml, but 0.77±0.22mμg/ml when measured with another antiserum. Similar findings were observed in IRG determination in the plasma samples obtained from a pancreatectomized patient containing gut glucagon alone. The recovery of gut glucagon added to plasma assayed with one antiserum differed from that using another, but those of pancreatic glucagon were the same without reference to antiserum employed.
These facts suggest a possible explanation for the widely divergent results reported for circulating glucagon levels.

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Serum FSH and LH levels were measured serially by radioimmunoassay in fifteen menstrual disordered or infertile subjects for two menstrual cycles, one control cycle and another cycle treated with clomiphene citrate. Lack of normal cyclic patterns that usually appear in ovulatory individuals of serum FSH and LH, however, within the range of normal levels in most subjects, as well as the day-to-day fluctuation of gonadotropin levels were observed in amenorrheic or anovulatory patients. By regarding the early rise of gonadotropins after clomiphene intake as a favorable response, those with fluctuating gonadotropin levels during untreated cycle were found to respond considerably to clomiphene citrate. Thus, a predictability is suggested. In the clomiphene-induced ovulatory cycles the serum FSH and LH exhibited either similar to those usually seen in normal ovulatory cycle or without a sequence of normal pattern but midcycle surge. The discordancy of gonadotropins stimulated by clomiphene which suggested the cause of temporal failure with this medicine was pointed out.

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