Endokrinologie最新文献

In a young male insulin-dependent diabetic patient with normal aldosterone levels an infusion of hypertonic glucose induced a paradoxical increase in serum potassium concentration and suppressed normally the elevated HGH levels, while on high sodium intake. On the other hand, during sodium restriction providing protection from the paradoxical hyperkalemia, a paradoxical increase in HGH level has been observed. A definite relationship was found between changes in serum potassium and HGH levels suggesting a possible role for the hypophyseal hormone in the cellular regulation of potassium distribution.

The physical state of rat adrenocortical lipids was studied by applying temperature-dependent techniques, including polarization microscopy and differential scanning calorimetry. Freeze-fracture detection was used for electron microscopic examinations. Temperature-dependent multiple phase transitions of adrenocortical lipids and their lamellar submicroscopic structure suggest a liquid crystalline state. This provides a possible explanation for the transition of storage lipids into liquid state, a precondition for their mobilization and processing by hydrolyzing enzyme system.

Pregnant rats were treated with dexamethasone in drinking water (10 micrograms/ml) from the 15th to the 22nd day of pregnancy. Dexamethasone significantly reduced the weight of rat fetuses and concentration of DNA, RNA and proteins in fetal adrenal glands, liver, placenta, brain, kidneys, heart, lung, testes and pituitary from the 17th to the 22nd day of pregnancy. These data show that dexamethasone given to pregnant rat may lead to potentially deleterious effects on fetal rat development.

The effects of estradiol benzoate (E2B) at a dose of 50 micrograms/day/rat for 15 days were investigated on ascorbate metabolism, steroidogenesis, protein, cholesterol levels of testis, adrenal and serum testosterone, LH and FSH profiles of rats. The data revealed that E2B manifested a direct effect on testicular and probably adrenal steroidogenesis. But serum gonadotrophin levels remained unchanged. The treatment also brought about a decline in ascorbate metabolism, activities of 3 beta and 17 beta hydroxysteroid dehydrogenases and alteration in protein level concomitant with the accumulation of cholesterol in both steroidogenic organs. Estrogen treatment was more effective in adult male rats than in the immature ones.

The effect of thyroxine on rat thyroid monoamine oxidase (MAO) activity in vivo and in vitro was studied in order to evaluate the nature of the inhibition of the enzyme. Monoamine oxidase activity was measured in rat thyroid homogenate. Thyroxine (200 micrograms kg-1) or triiodothyronine (40 micrograms kg-1) injected in vivo inhibited the activity of monoamine oxidase (MAO) significantly (P less than 0.05). Thyroxine (T4), 10 micrograms added to the incubation mixture during 20 min also inhibited MAO activity in thyroid homogenate. A Lineweaver-Burk plot of the data obtained shows that the inhibition is of the uncompetitive type.

The binding of 19 steroids to the vesicular androgen receptor has been studied under cell-free conditions. Rate constants of association and dissociation were determined for the binding of 3H-5 alpha-dihydrotestosterone (3H-DHT) and 3H-testosterone with the receptor. The Scatchard-analyses of the two reactions were also performed to determine the equilibrium binding constants. The values obtained were significantly different from those calculated from the kinetic constants, which was due to the relative inaccuracy of equilibrium analysis in our system.

The aim of the present investigation was to ascertain whether intermale aggression (by fighting) affects thyroid gland activity in wild rat. Following intermale aggression for three hours, thyro-follicular epithelial height was significantly decreased and colloidal content in follicular lumen increased only in the subordinate rats whereas the thyroid gland of the dominant rats was not perceptibly changed. Thus, aggression inhibits thyroid gland activity only in the subordinate rats. It is suggested that this effect may be due to psychosomatic rather than physical stress during aggression.

The age dependency of changes in food intake and body weight in Wistar rats after androgen and estrogen treatment was followed. The 5 age categories of female rats were treated by androgen and the 6 age categories of male rats were treated by estrogen. The androgen treatment induced an expressive increase in weight gains in all age categories of female rats, except the 1st (after birth), during 25 days from the beginning of the experiments. The increase of weight gains resulted in significantly higher body weight on the 25th day of experiments in the experimental rats. The differences in weight gains among the individual experimental groups after androgen treatment show a rising effect with the age of the animals. There was only a slight increase of food intake in the older experimental groups during the androgen treatment. The estrogen treatment in male rats induced an expressive decrease in weight gains in the 2nd age category (after weaning) and losses of body weight in older experimental groups during 20 days from the beginning of the treatment. The body weight of experimental animals on the 20th day was significantly lower than in the control ones. The losses of the body weight after the estrogen treatment rose with the age of the rats. The food intake was also considerably decreased by estrogen treatments, approximately equally in all experimental groups. The comparison of magnitude of the changes in food intake and body weight after androgen and estrogen treatments indicates that the primary effect of these hormones is their anabolic or catabolic activity which secondarily induces the changes in food intake and its utilization.

A new class of modified progesterones with an additional 16 alpha, 17 alpha-carbocycle (pregna-D'-pentaranes) is obtained. These compounds were found to exhibit a high progestational activity in the Clauberg-McPhail assay and to be active as well in the pregnancy maintenance test in ovariectomized rabbits. Some of the pentaranes displayed a remarkable contraceptive effect in combination with mestranol. X-Ray data were employed for the description of molecular conformations of D'-pentaranes. On this base, their biological responses are considered to be connected with the conformational changes of D and D' rings as well as 17 beta-acetyl side chain. Accordingly, the contraceptive effect of D'3-6-pentaranes is correlated with the value of C(15)-C(16)-C(17)-C(20) torsion angle of the corresponding molecules. The relative binding affinities of some D'6-pentaranes to the progestin receptor were determined and compared with their in vivo biological responses.