Anterior pituitary function in 23 patients (16 men and 7 women, aged 27 to 68) with isolated ACTH deficiency was analyzed. Four were our own cases while the other 19 cases were ascertained by questionnaire.
Both the baseline TSH levels and the peak TSH responses to TRH were high before treatment in more than half the cases but were normalized after treatment. This abnormality was found in patients younger than 50. The peak prolactin responses to TRH were excessive before and after treatment in three-fourths of the cases but decreased after treatment. The peak HGH responses to ITT were excessive in 3 patients before treatment and increased after treatment in 5 out of 6 cases. The peak LH and FSH responses to LH-RH were low or high in 20-30% of cases, but these abnormal responses were reduced to half after treatment.
These results demonstrate that many disorders of the anterior pituitary function were found in patients with isolated ACTH deficiency but that these disorders became normal after treatment.

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To investigate the prevalence and characteristics of subclinical hypothyroidism in aged subjects, determinations of plasma TSH levels were made in 172 patients (54 males and 118 females) over the age of 55, who were examined in the out-patient clinic. Although they had one of the clinical signs of hypothyroidism such as a puffy face, dry skin, general malaise, cold intolerance, constipation, hypercholesteremia and elevated serum LDH level, they had no other clinical picture of overt hypothyroidism. Their underlying lesions were hypertension, cardiac diseases, cerebrovascular diseases, chronic obstructive lung disease, mild diabetes mellitus (type II) and mild liver diseases. All the patients were apparently in a normal nutritional state without any specific medications which could cause thyroid abnormalities. Patients with overt thyroid diseases or severe illness were not included in the present study. In addition, the occurrence of anti-thyroid antibodies were also investigated in sera from 112 of 172 patients, using the thyroglobulin-coated and microsome-coated tanned red cell hemaglutination tests.
Seventeen (6 males and 11 females) subjects, aged 58 to 83, had elevated plasma TSH levels, ranging from 12.1μU/ml to 170μU/ml. Although the incidence of circulating thyroid antibodies in 112 patients examined was apparently higher (5.7% in men and 19.5% in women) than that reported previously in control subjects, 15 of 17 patients with elevated TSH levels had no detectable thyroid antibodies in repeated determinations. Previous reports have suggested that latent thyroid failure detected in aged subjects might be mainly due to Hashimoto's thyroiditis. However, the present findings suggest the existence of other factor (s) as a cause of subclinical hypothyroidism in aged subjects.
Since 16 of 17 patients with elevated TSH levels had elevated ^99mTc thyroid uptake, ranging from 2.5% to 12.9%, the perchlorate discharge test was performed 6 hours after the administration of ¹²³I. In 15 of 17 cases, ¹²³I thyroid uptake was markedly diminished immediately after the administration of 1 g perchlorate, and the discharge rates ranged from 27% to 88% (mean ± SE = 67 ± 5%). Moreover, 13 of 15 patients with positive perchlorate discharge test had markedly diminished T₄ levels in serum (mean ± SE = 2.7 ± 0.5μ/dl in 15 patients), and 13 patients had almost normal T₃ levels (mean ± SE = 107 ± 8ng/dl in 15 patients), indicating “T3-euthyroidism” in these patients. On the other hand, 2 patients with negative perchlorate discharge tests showed completely normal T₄ and T₃ levels in serum. Four patients had a very small goiter detected only by careful palpation, and the remaining 13 patients had no detectable goiters even in CT scan examination. Furthermore, the histological features of Hashimoto's thyroiditis were not found in the thyroid biopsy specimens obtained from 2 patients with a positive perchlorate discharge test.
The present findings suggest that in aged subjects there exists subclinical hypothyroidism attributable to defective iodination in the thyroid, which is caused by some factor other than Hashimoto's thyroiditis. Whether or not the iodination defects in the thyroid arise from aging remains to be determined by future investigation.

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Although insulin is rapidly metabolized by various tissues probably through the actions of enzymes with a high degree of specificity, the mechanism of insulin degradation in the target cell is not yet sufficiently clarified. Using the cell fractionation of rat liver, insulin degradation by plasma membrane, lysosomal, microsomal, and cytosol fractions were examined under various conditions including high and low substrate concentrations, pH 7 and pH 4, with and without glutathione, and in the presence of antiserum against pig muscle insulin-degrading enzyme (IDE). Furthermore, to clarify the biological significance of the insulin-degrading system in these cell fractions, insulin-degrading activities of liver cell fractions from streptozotocin diabetic rats were compared with those from control rats under various assay conditions.
At neutral pH and low insulin concentration (0.1nM), insulin was degraded predominantly by the cytosol fraction, and its activity from diabetic rats was significantly lower than that from control rats. Insulin-degrading activity in the cytosol fraction was identical to pig IDE in most of its enzymatic properties including Km for insulin (120nM), sulfhydryl-dependency, and the effect of anti-IDE serum. At neutral pH and high insulin concentration (8.5μM), the highest activity was found in microsomes, and its activity from diabetic rats was lower than that from control rats. Insulin-degrading activity in the microsomal fraction was mainly due to glutathione-insulin transhydrogenase, judging from its Km for insulin (15μm) and the great effect of glutathione. However, the physiological importance of this enzyme was cast in doubt because of its high Km for insulin.
At the acid pH, most insulin degradation occurred in the lysosomal fraction. Lysosomal activity from diabetic rats was significantly decreased at either high or low insulin concentration under acid conditions, whereas no significant differences were shown between diabetic and control rats under neutral pH. Insulin-degrading activity of plasma membranes was identical to IDE. Plasma membranes contained relatively little degrading activity under every assay condition and no changes were seen between both groups of rats.
These data suggest that insulin is mainly degraded by intracellular enzymes rather than the insulin-degrading system on plasma membranes and that IDE seems to account for most of the intracellular degradation of insulin.

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Recently, the predominant molecular forms of cholecystokinin (CCK) in extracts of tissues from the central nervous system and small intestines of adult man and hog have been demonstrated to correspond to the COOH-terminal octa- and tetra-peptide of CCK. CCK is one of the established gastro-intestinal hormones capable of stimulating pancreatic exocrine secretion. In addition, pure natural porcine CCK, synthetic COOH-terminal octa-peptide of CCK and synthetic caerulein which contains a COOH-terminal penta-peptide identical to CCK have been shown to stimulate insulin and glucagon secretion in vivo and in vitro. Thus, it seems reasonable to expect some effect of these COOH-terminal fragments of CCK on pancreatic exocrine and endocrine secretion. The present study was, therefore, undertaken to compare the various COOH-terminal fragments of CCK with those effects on pancreatic exocrine and endocrine secretion in the rat.
Pancreases from male Wistar rats, fed ad libitum, were isolated according to the technique of Kanno. Perfusate consisted of a Krebs Ringer bicarbonate buffer containing 4.6% Dextran T-70 and 0.25% bovine serum albumin. The effects of various COOH-terminal peptides of CCK (synthetized by Prof. Noboru Yanaihara, Shizuoka) at the doses ranging from 10^-11 to 10^-8M were studied in the presence of 50mg/dl or 150mg/dl glucose. Insulin (IRI) and glucagon (IRG) levels in the portal effluent were determined by radioimmunoassay using polyethyleneglycol and charcoaled dextran with antiserum 30K, respectively. Amylase activities in the pancreatic juice were assayed by a chromogenic method with blue-dyed starch polymer.
In the presence of 50mg/dl glucose, IRI and IRG responses to the COOH-terminal octa-peptide of CCK (CCK-8) occurred at high doses, more than 10^-9M. On the other hand, IRI and IRG releasing doses of CCK-8 resulted in lower rates of release of fluid and amylase when compared with those stimulated by the maximally effective doses of CCK-8.
In the presence of 150mg/dl glucose, CCK-8 at a submaximally effective dose of 10^-10M for the exocrine pancreas potentiated the IRI response to glucose stimulation. These results were completely consistent with our previous findings obtained with natural porcine CCK and caerulein. The COOH-terminal deca-peptide (CCK-10) and tetradeca-peptide (CCK-14) at a dose of 10^-10M also potentiated the effluent IRI response to glucose stimulation. However, the IRI responses to CCK-8 and CCK-14 were biphasic, but the IRI response to CCK-10 was monophasic and transient. Moreover, the maximal IRI response just after the perfusion of these peptides was greater in CCK-8 than in CCK-10 or CCK-14. On the other hand, the effluent IRI responses to the COOH-terminal tetra-peptide of CCK (CCK-4) or deamidated CCK-8 (CCK-8-OH) at a dose of 10^-10M was not significantly increased as compared to that obtained with glucose stimulation alone. In addition, the combined perfusion with 10^-10M CCK-8 and 10^-8M CCK-8-OH resulted in a lower IRI response than that obtained with the perfusion of CCK-8.
From these observations, it may be concluded that CCK-8 at a submaximally effective dose for the exocrine pancreas has a glucose-dependent insulinotropic action and that the amino acids from the position 5 to 8 of the COOH-terminus and the NH₂ -residue of the COOH-terminal phenylalanine are important for the insulinotropic action of CCK.

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In order to clarify the possible participation of dopaminergic control on the endocrine pancreas, a dopaminergic antagonist, sulpiride, was given intravenously to 12 normal subjects and 26 diabetics. After the intravenous administration of sulpiride with or without arginine HCl, blood samples were withdrawn at 0, 15, 30, 45, 60, 90 and 120 min and were stored at -20°C until the measurements of blood glucose, serum immunoreactive insulin (IRI) and plasma immunoreactive glucagon (IRG) were taken.
In the first experiment, 100mg of sulpiride was administered solely to 5 normal subjects and 7 diabetics. Though blood glucose levels were not significantly changed, plasma IRG levels were significantly lower at 45 min after the injection in normal subjects and at each 30, 60 min in diabetics. From the results of the first experiment, sulpiride was thought to be able to suppress plasma IRG levels; then the second experiment was performed.
In the second experiment, 7 normal subjects and 19 diabetics were employed. Both arginine HCl infusion and arginine HCl with 100mg sulpiride infusion were performed in order to compare the difference between IRI and IRG responses to the two provocations. In comparison with the arginine HCl infusion, IRI secretion seemed to be enhanced and IRG secretion seemed to be diminished in the simultaneous administration of arginine HCl and sulpiride. This was more obvious in comparing a glucagon or insulin area which was calculated by the integration of the curves circumscribed by a plasma IRG or serum IRI for the periods of 0-120 min. The glucagon area was significantly (p <0.05 in normal subjects; p <0.01 in diabetics) smaller in arginine HCl and sulpiride infusion than in arginine HCl alone. The insulin area seemed to be greater with the simultaneous administration of arginine HCl and sulpiride than with arginine HCl alone, but this difference was not significant.
It was found through the two experiments that the dopamine antagonist, sulpiride, suppressed the basal and arginine-induced IRG secretion. Therefore, the results of the present study might suggest the existence of a dopaminergic system in the endocrine pancreas.

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