This study was undertaken to gain better insight into dehydroepiandrosterone-sulphate (DHEA-S) secretion in rats, which is necessary for the subsequent investigation of the influence of nutritional status on DHEA-S secretion in this species (published as part II). DHEA-S as well as corticosterone (11-OHCS) blood levels were found to be markedly lower in dexamethasone-treated than in untreated rats. After adrenocorticotropic hormone (ACTH) administration DHEA-S and 11-OHCS increased significantly. A similar rise was seen for DHEA-S in metyrapone-treated rats. At the same time these animals exhibited a drastic elevation of 11-desoxycorticosterone (11-DOC). Furthermore DHEA-S levels of rats pretreated with ACTH prior to metyrapone application significantly exceeded the DHEA-S values measured in animals only given metyrapone. However, the DHEA-S level did not change clearly in rats treated with either a single or multiple doses of hCG, although the concentrations of DHEA, androstenedione, and testosterone were markedly elevated in these animals. These findings suggest that DHEA-S in rats is secreted chiefly (or exclusively) by the adrenal gland. Since a stimulative effect of ACTH pretreatment on the secretory DHEA-S response to subsequent metyrapone stimulation could be demonstrated, we conclude that stress (ACTH administration) associated with a stimulation of adrenal gland activity provokes an increase in the secretory capacity for DHEA-S.
After more than one month under growth-restraining feeding conditions the influence of undernutrition (50% feed restriction) on dehydroepiandrosterone sulphate (DHEA-S) and 11-OHCS (corticosterone) secretion was investigated in male Wistar rats. Diet-restricted (DR) rats, untreated before the taking of blood samples, showed clearly elevated 11-OHCS plasma levels in the morning (lights-on) compared to ad libitum-fed (AL) control rats, whereas the evening (lights-off) 11-OHCS levels were almost identical in both groups. The corresponding DHEA-S blood concentrations were equal under both feeding schedules in the morning as well as in the evening. However DHEA-S response to adrenocorticotropic hormone (ACTH) administration was significantly elevated in DR rats compared with AL rats. No such difference was detectable for ACTH-stimulated 11-OHCS blood levels. Measurement of total adrenal cholesterol content revealed a markedly higher concentration of this hormone precursor in the glands of untreated DR rats than in the adrenals of the AL control group, thus clearly indicating the existence of a chronically elevated endogenous ACTH secretion under dietary restriction, since continued in vivo ACTH stimulation is known to increase the cholesterol content of the adrenal cortex. Furthermore the occurrence of a nutritional stress is obviously reflected by the elevated 11-OHCS levels in the circulation of DR rats at “lights-on.” The observations in DR rats coupled with the findings in ACTH-pretreated rats under metyrapone treatment (J. Clin. Biochem. Nutr., 2, 141-152, 1987) strongly support our already proposed concept that stress or stimulation of the cortico adrenal activity provokes an increase in the capacity for secretion of DHEA-S measurable after an appropriate stimulation. Contrary to a recently published hypothesis undernutrition appears to be not necessarily associated with a suppression of enzymes involved in DHEA-S formation.
The role of lipid peroxidation in the pathogenesis of gastric ulcer was investigated in a rat model produced by burn shock. After the immersion of rats in 80°C water for 10min, blood pressure was significantly decreased, and serum levels of lysosomal enzymes, such as acid phosphatase and β-glucuronidase were significantly increased. These findings indicate that the burned rats were in shock states. Blood flow of the gastric wall was significantly decreased and hemorrhagic erosions were seen in the body of the stomach. Thiobarbituric acid-reactive substances, an index of lipid peroxidation, in the serum and the gastric mucosa were significantly increased after the burn. These changes appeared before the severe injury of the gastric mucosa, indicating that lipid peroxidation plays a significant role in the pathogenesis of the gastric mucosal lesions induced by burn shock.
We examined resected adrenocortical adenoma and adjacent atrophic adrenal tissue from a patient with Cushing's syndrome for phospholipid/calcium-dependent protein kinase (C-kinase) activity. Cytosolic C-kinase activity was higher in adrenocortical adenoma than in adjacent adrenal tissue, while C-kinase activity in the particulate fraction was lower in adrenocortical adenoma than in adjacent adrenal tissue. Upon stimulation of isolated adrenocortical adenoma cells with β 1-24 ACTH (10-7M), C-kinase activity in the cytosolic fraction was increased from 7pmol/min/mg protein (basal) to 107pmol/min/mg protein by 120min after stimulation. On the other hand, C-kinase activity in the particular fraction of the isolated cells was considerably decreased from 884pmol/min/mg protein (basal) to 179pmol/min/mg protein over the same period. These results suggest that C-kinase activity of adrenocortical adenoma cells was translocated from the particulate to the cytosolic fraction by ACTH-stimulation.
A rapid two-site enzyme immunoassay (EIA) for human epidermal growth factor (hEGF) was developed. Our rapid EIA was based on the sandwiching of an antigen between anti-hEGF IgG-coated polystyrene beads and anti-hEGF Fab'-linked peroxidase (horseradish peroxidase, EC. 220.127.116.11). This method is so rapid that we can get the results within 5h. The reproducibility of within- and between-assay was 4.8 to 7.1% and 3.5 to 7.2%, respectively. And discriminatory sensitivity was as low as 5pg/ml. The recovery of hEGF from urine and serum by this method was approximately 100%, and the serial dilution curves of unextracted human urine and serum samples were parallel with that of standard hEGF (Urogastrone). We applied this method to assay of hEGF content in urine of patients with a variety of tumors.
Carnitine metabolism in a patient with methylmalonic aciduria was investigated. The patient showed a low level of free carnitine and a slightly increased level of acylcarnitine in her serum and urine. After carnitine therapy, acylcarnitine excretion in the urine increased markedly, and the patient had a favorable body weight gain. A small dose of valine was administered with or without the carnitine supplement. This induced metabolic changes, e.g., hypoglycemia and hyperketonemia, with little changes in lactate, pyruvate and ammonia levels. The level of free carnitine in the serum decreased gradually and acylcarnitine was increased by valine administration. These metabolic changes were not much different with or without carnitine supplement. Natural protein tolerance was then investigated. The patient could not tolerate 1.5mg/kg/day of natural protein because of nausea, vomiting, and body weight loss without carnitine. Although nausea and loss of apetite were also seen under carnitine therapy, vomiting did not occur when the patient received 1.5mg/kg/day of natural protein. These results show the usefulness of carnitine for the management of methylmalonic aciduria with restriction of natural protein.