Alterations of pancreatic juice amylase by glucocorticoid levels in the rat

By use of isoelectrofocusing, three isoenzymes with pIs of 8.40, 8.55, and 8.65 were characterized in the amylase fraction of rat pancreatic juice. Enzyme secretion in rat exocrine pancreas is affected by glucocorticoid levels; adrenalectomy led to a significant decrease in protein secretion which was more pronounced in the amylase fraction, in which the isoenzymes with pI 8.55 and 8.65 disappeared. Substitution therapy with hydrocortisone (25 mg/kg/day, for 6 days) restored exocrine pancreatic secretion to almost normal levels. Administration of hydrocortisone to control rats led to structural alterations in enzymes secreted, splitting the amylase isoenzymes with pI 8.40; this was confirmed by crossed immunoelectrophoresis. It is concluded that glucocorticoid levels play an important role in the maintenance of function of exocrine pancreas and it is suggested that, although hydrocortisone fulfills the objective of restoring enzyme secretion diminished by adrenalectomy, it is possible that intensive treatment could have undesirable effects on the structure of enzymes and could involve pancreatic disfunctionality.     

Glucocorticoid modulation of prolactin receptors on mammary cells of lactating mice.

Prolactin receptors were monitored by measuring 125I-labeled prolactin binding to collagenase-dissociated mammary epithelial cells of lactating BALB/c mice. Specific receptors for iodine-labeled prolactin with an apparent dissociation constant (Kd) of 0.99 . 10(-9) M were present on the dissociated mammary cells. The binding was inhibited by ovine prolactin, human growth hormone and human placental lactogen but not by follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, bovine growth hormone or insulin. Adrenal ablation of nursing mothers caused a reduction of the number of prolactin receptors and this effect was preventable by hydrocortisone therapy. Hydrocortisone injections to mothers 3 days after adrenalectomy also induced a replenishment of the prolactin receptors on the mammary cells. Injections of progesterone failed to sustain the high level of mammary cell prolactin receptors in adrenalectomized animals. Stimultaneous injections of hydrocortisone and progesterone to animals 3 days after adrenalectomy caused a partial suppression of the stimulatory action of hydrocortisone alone. The results suggest that hydrocortisone can exert a modulatory influence on mammary cell prolactin receptors in non-hypophysectomized post-partum mice without altering the dissociation constant (Kd) of the receptors.     

A karyometric and stereologic study of the effects of gonadotrophin and testosterone on the interstitial gland of the testis of intact and endoxan treated rats

Adult male rats were treated daily for 18 days with endoxan in doses of 4 mg/kg of body weight or testosterone in doses 2.5 mg per rat. For the last 5 days of the experiment some of the rats received gonadotrophin injections in doses of 50 I.U. Karyometric and stereologic studies were undertaken on paraffin sections of the testes stained with haematoxylin and eosin. Endoxan treatment decrease the nuclear volume of the Leydig cells and lowers the volume fraction occupied by the interstitial gland in the testis. These changes were accompanied by a decrease in the intensity of reaction for acid phosphatase, non-specific esterases and 3-beta-hydroxy-steroid dehydrogenase. Testosterone injected alone or jointly with endoxan resulted in more pronounced changes than following treatment with endoxan alone. As expected, gonadotrophin injections into intact rats resulted in a marked increase in nuclear volume of the Leydig cells and in the volume fraction of the interstitial gland. This effect of gonadotrophin on the interstitial gland of the rat testis was partially inhibited by endoxan treatment. It follows from these experiments that endoxan impairs the functional activity of the interstitial gland of the rat testes by lowering the endogenous gonadotrophin levels, as well as by direct action on the Leydig cells.     

Involution of hyperplastic goitre in the adult male rat. Tissue compartment process with early iodide effect: a stereological and biochemical study

The morphological and functional changes during involution of hyperplastic goitre have been investigated in the adult male rat. Male wistar rats received an iodine-deficient diet for 6 months and during the last 2 months received propylthiouracil (PTU, 0.15%). By the end of this treatment (day 0), a hyperplastic goitre was obtained. A normal iodine supply was then given and PTU withdrawn. During the first 8 days of iodine refeeding, the plasma thyrotropin (TSH) remained at a high level (ten times the control value), whereas the thyroid iodide content was low on day 0, markedly increased on day 1 and decreased on day 4. Plasma T3 and T4 levels remained unchanged for 4 days and only increased on day 8. The total thyroid protein concentration was low on day 0 and then increased rapidly on day 8 (by 34%). The volume density of colloid remained low and unchanged until day 8, when it started to increase. However, the thyroid epithelial cell volume and the volume density of capillaries were raised on day 0, decreased rapidly in the next 8 days and more slowly later on. The total number of thyroid epithelial cells was considerably raised in the hyperplastic gland. It did not vary until day 16, when it decreased slowly, reaching a plateau on day 45 above the control value. The present data show that involution of hyperplastic goitre in the rat is due essentially to a decrease in thyroid epithelial cell volume and to a reduction of the increased number of capillary blood vessels present. The decrease in the number of epithelial cells is only 16.5%, suggesting that the death of thyroid epithelial cells contributes little. Half the process of involution, which occurs from days 0 to 8, is controlled by the thyroid iodide concentration rather than TSH, indicating the involvement of a thyroid autoregulatory mechanism. It must be emphasized, however, that the discontinuous pattern of epithelial cell number during involution may indicate that some cells with larger nuclei and more rapid turnover disappear more quickly after iodine refeeding.     

Sympathetic and adrenocorticoid influences on diet-induced thermogenesis and brown fat activity in the rat

Bilateral adrenalectomy markedly reduced body weight and energy gain and energetic efficiency of adult cafeteria-fed rats but enhanced the thermogenic response to food and stimulated brown fat activity. These changes were totally prevented by replacement of the animals with corticosterone (1 mg/rat/day). Unilateral denervation of the sympathetic nerves supplying the interscapular brown adipose tissue abolished the enhanced activity resulting from adrenalectomy and inhibited thermogenic activity in brown fat from cafeteria rats with intact adrenals, but had no effect in adrenalectomised animals treated with a high dose of corticosterone.     

Nonspecific esterase and alpha-glycerolphosphate dehydrogenase activity and the fat content in the regenerating chicken liver]

The data on histochemical study of changes in the activity of esterases, alpha-glycerophosphate dehydrogenase and the fat content in the chick regenerating liver are presented. The accumulation of the fat in hepatocytes during the early periods of regeneration (1--5th day of the experiment) is partially conditioned by the reduction of the activity of nonspecific esterases. The maximal liver steatosis is accompanied also by an increase in the activity of alpha-glycerophosphate dehydrogenase which indicates intensification of glycolysis and synthesis of triacylglycerines (liver spare lipids) during regeneration.     

Premature induction of glucokinase in the neonatal rat by thyroid hormone.

1. It was shown that the development of liver glucokinase in the rat coincided with a peak in the levels of circulating thyroid hormone at about the 16th postnatal day. 2. Administration of thyroid inhibitors blocked the development of the enzyme and administration of thyroid hormone restored activity to normal levels. 3. Glucokinase could be induced prematurely as early as the 2nd postnatal day by the administration of thyroid hormone followed by daily injection of glucose (10 mg/g body weight). 4. Glucocorticoids and corticotropin failed to induce glucokinase activity prematurely. 5. The postnatal increase in circulating thyroid hormone levels together with increased intake of carbohydrate at weaning may be the normal physiological stimulus for induction of this enzyme.     

Hormonal control of metabolism of gamma-aminobutyric acid in the rat hypothalamus and hippocampus

It has been established that hydrocortisone administration increased the amount of total, free, bound and synaptosomal GABA in the hypothalamus, glutamate decarboxylase activity in the homogenate and synaptosomes and time of the mediator turnover. ACTH administration increased the GABA content and glutamate decarboxylase activity in synaptosomes. The total amino acid content and time of its turnover got higher only with single hormone administration. In the hippocamp hydrocortisone administration increased the total and free GABA contents, its turnover time, glutamate decarboxylase activity in the homogenate and decreased GABA-aminotransferase activity in the homogenate and synaptosomes. The GABA level in synaptosomes grew only with multiple hormone administration. Single administration of ACTH decreased the total GABA content, glutamate decarboxylase activity in the homogenate, while its multiple administration increased the GABA level in synaptosomes followed by a decrease of GABA-aminotransferase activity in the homogenate and synaptosomes. The GABA turnover time fell with single hormone administration and grew with the multiple one. Adrenalectomy induced no changes in the GABA content and activity of its metabolism enzymes in the hypothalamus, however the bound GABA level decreased, while the turnover time increased. In the hippocamp adrenalectomy decreased total, free and synaptosomal GABA contents, glutamate decarboxylase activity in a homogenate and turnover time. Subsequent hydrocortisone administration only partly normalized the revealed changes of the GABA metabolism in the brain structures under adrenalectomy.     

Hypercalcemia in glucocorticoid withdrawal

We found severe hypercalcemia in the course of hydrocortisone withdrawal in a patient who had undergone unilateral adrenalectomy to resect a cortisol-hypersecreting adenoma. Serum calcium gradually but progressively increased after unilateral adrenalectomy. Severe hypercalcemia developed on the 77th postoperative day (the 15th day after discontinuing hydrocortisone replacement). The serum concentration of calcium, PTH, 25(OH)D, and 1,25(OH)2D were 8.0 mEq/l, less than 100 pg/ml, 10.1 ng/ml and 29.6 pg/ml, respectively. This hypercalcemia was accompanied by marked urinary hydroxyproline excretion and less calcium excretion in the urine than the prevailing level of serum calcium. Serum concentrations of 25(OH)D, 1,25(OH)2D and PTH were not elevated during the severe hypercalcemia. We concluded that the hypercalcemia in this patient was due in part to enhanced bone resorption and increased renal tubular reabsorption of calcium as a result of glucocorticoid withdrawal, but not to the elevation of serum PTH or serum 25(OH)D and serum 1,25(OH)2D.     

Glucocorticoid modulation of prolactin receptors on mammary cells of lactating mice

Prolactin receptors were monitored by measuring ¹²⁵I-labeled prolactin binding to collagenase-dissociated mammary epithelial cells of lactating BALB/c mice. Specific receptors for iodine-labeled prolactin with an apparent dissociation constant (K_d) of 0.99 · 10^?9 M were present on the dissociated mammary cells. The binding was inhibited by ovine prolactin, human growth hormone and human placental lactogen but not by follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, bovine growth hormone or insulin. Adrenal ablation of nursing mothers caused a reduction of the number of prolactin receptors and this effect was preventable by hydrocortisone therapy. Hydocortisone injections to mothers 3 days after adrenalectomy also induced a replenishment of the prolactin receptors on the mammary cells. Injections of progesterone failed to sustain the high level of mammary cell prolactin receptors in adrenalectomized animals. Stimultaneous injections of hydrocortisone and progesterone to animals 3 days after adrenalectomy caused a partial suppression of the stimulatory action of hydrocortisone alone. The results suggest that hydrocortisone can exert a modulatory influence on mammary cell prolactin receptors in non-hypophysectomized post-partum mice without altering the dissociation constant (K_d) of the receptors.     

Morphofunctional characteristics of the endocrine cells of the stomach following administration of hydrocortisone and L-thyroxine

Electron microscopy with application of specific fluorescent histochemical reaction of Falck, as well as some methods of impregnation made it possible to indentify enterochromaffin cells in the stomach of hyperthyroid rats and the rats after cortisone injection under the conditions ox hyperfunction of the thyroid gland. After 20 days of L-thyroxin injection, and after 10 days of hydrocortisone injection, preceded by L-thyroxin, the amount of enterochromaffin cells in the epithelial layer of the gastric mucosa were noted to increase that was accompanied by simultaneous increase of the number of secretory argyrophil granules in their cytoplasm. Simultaneous injection of L-thyroxin and hydrocortisone, while not decreasing statistically significant amount of the cells, produced degradation of their cytoplasm.     

Comparison of three histometric methods for the comprehension of stimulating effects on the rat thyroid gland

There exist some histometric methods for the morphological quantification of different strongly stimulating effects on the thyroid gland induced by drugs and/or other chemical substances in dependence upon dose and duration of application. But in respect of technical and temporal expense and also diagnostic statement, there are considerable differences between these recording procedures. Therefore we examined the 3 mostly used methods synchronously (i.e. determination of thyroid epithelial cell height, nuclear volume in thyrocytes, and estimation of relative volume parts in the thyroid gland by the point counting method) by investigating the thyroid glands of methylthiouracil-(MTU)-stimulated rats and corresponding controls in order to compare the diagnostic value and temporal expense. The largest temporal expense was required in the nuclear volume determination, the smallest in the point-counting method. On principle, all 3 procedures allow the determination of hypertrophic alterations but only by help of the point-counting method, also hyperplastic changes are recognizable. By nuclear volume determination, we found significant differences between central and peripheral parts of the thyroid gland. Therefore, to avoid the subjective error, it will be necessary to measure a large number of nuclei in many planes of the gland. Also the determination of epithelial cell high reinforces the subjective error because of the heterological structure especially in unstimulated thyroid gland. If the number of counting points is exactly determined and, full of sense, limited, the point-counting method allows a nearly complete measuring of the whole object to be tested within an acceptable investigation time. In this way, the heterological structure of thyroid gland will be regarded, and comparability and reproducibility are guaranteed on an high level.     

Nuclear triiodothyronine receptors in the testis of the growing rat are regulated by the thyroid status]

The effects of thyroid status on the binding capacity, association constant (Ka) and receptor occupancy during postnatal rat testis development were evaluated. Hypothyroidism (induced by oral administration of 0.05% methimazole from the day of birth) increased the total T3 binding capacity in the testis, retarding the normal developmental decrease in T3 receptor number (mean maximal binding capacities estimated by Scatchard analysis for 21-day-old eu- and hypothyroid rats were 117 and 173 fmol/mg DNA, respectively). The rat thyroid status also affected the percentage of T3 receptor occupancy but not the affinity of binding (as measured by Ka). The postnatal developmental changes in T3 binding capacity induced by hypothyroidism were completely reversed by T3 replacement. These results suggest that T3 nuclear receptors in the developing rat testis are modulated by thyroid hormones.     

Study of rat pulmonary macrophages as affected by hydrocortisone administration and adrenalectomy

The blood clearance rate of inert colloidal particles and the number of rat lung interstitial phagocytic cells decrease considerably on the 7th day after daily subcutaneous hydrocortisone acetate (HC) injection at a dose of 125 mg/kg. The number of cells in the bronchoalveolar lavage (BAL) increases more than 5-fold, and the absolute quantity of neutrophils is 66 times higher than in the control. Phagocytic and microbicidal activity of HC-treated animal alveolar macrophages (AM) decreases. Stimulation with zymosan led only to the recovery of the normal parameters of mononuclear phagocytosis system (MPC) and its pulmonary compartment activity. The parameters of MPS and AM studied increase on the 7th day after bilateral adrenalectomy (AE). The number of BAL cell increases 1.4-fold due to the animals' death immediately after intravenous zymosan injection because of total hemorrhage. The data obtained testify to the influence of glucocorticoids on the composition and activity of bronchoalveolar space cells, which in turn determine the resistance of the lung tissue.     

An increase of CDP-choline: diglyceride phosphocholine transferase reaction in microsome fraction and its decrease in nuclear membranes of the rat liver after treatment with hydrocortisone

The availability of CDP-choline: diaglyceride phosphocholine transpherase activity in the rat liver nuclear membrane fraction is shown. It is established that the enzyme activity in nuclear membrane fraction makes up less than 1/3 of the analogous activity in microsomes. The hydrocortisone treatment of animals leads to an increase of the enzyme activity in microsomes and to a decrease in the nuclear membranes. The obtained data indicate the existence of the own enzyme of phosphatidyl choline synthesis in the nuclear membranes. This enzyme is, probably, responsible for the nuclear membrane structure when the functional status of cell changes.     

Studies of microsomal glucose-6-phosphatase on liver of irradiated rats

The activity of microsomal glucose-6-phosphatase (EC 3.1.3.9) on male rat liver was measured 1-9 days after whole-body gamma-irradiation. A marked fall of activity, expressed per whole liver, was observed reaching a minimum on the 4th day following irradiation. The enzyme activity is partially and momentarily restored (on day 7), before a new decrease occurred. Furthermore, when the results are expressed per milligram of microsomal proteins, there was no change. Cysteamine, when injected in vivo, kept up the glucose-6-phosphatase of whole liver. On day 4, a histochemical demonstration of the enzyme in liver cells is in accordance with enzyme measures. These observations suggested that the enzyme quantity was altered during the acute radiation syndrome in the rat.     

The development of the guinea pig gallbladder epithelial cells. II. Electron microscopical and enzymhistochemical investigations (author's transl)]

The development of the guinea pig gallbladder epithelium follows a distinct time schedule. During the first phase (up to 30th day of intrauterine life) the epithelial cells increase in number. They remain small and undifferentiated. In the second phase, from the 30th to the 44th day, cytodifferentiation is a dominating feature. The epithelial cells increase in height, the nuclei become more basal, the cells acquire their final zonal structure and the cell organelles exhibit their characteeristic appearance. Weak enzyme activities can be observed. In the third phase, from the 45th day until birth, there is functional differentiation and the adult pattern of enzyme distribution is established. Glycogen appears first on day 29, increases in amount and then disappears by day 57. There is a marked development of the Golgi apparatus associated with increased synthesis of secretory material. Between the 59th embryonic day and the 6th day of life mucoid cells with different functional states appear in the gallbladder epithelium. Later on these cells can be visualized only in the depths of the invaginations. After birth the epithelial cells become more columnar and by 10 days after birth the adult appearance of the epithelium is fully established.     

Enzymatic activity of Ammon's horn in the ontogenetic development of the rat.

Studies were performed on the activity of several enzymes in Ammon's horn of rat during an individual postembryonal development. For the studies rats of Wistar strain were used that were killed on the 1st, 3rd, 8th, 17th, 40th and 60th day after birth. In the experiment the brains were removed, cut, and the activity of dehydrogenases, phosphatases and esterases was revealed. During the performed studies some considerable differences were shown in the activity of several dehydrogenases, in each particular field of Ammon's horn, undergoing changes in the periods of ontogenetic development under study. Furthermore, some distinct differences in the phosphatases and esterases activity were revealed in each area of the Ammon's horn. Attention was drawn to a comparatively late histo-enzymatic maturation of Ammon's horn in comparison with other structures of the limbic system.