The effect of 4-aminopyrazolo (3,4-d) pyrimidine (4-APP) on some parameters of carbohydrate metabolism in the rat

The study was designed to evaluate some parameters of carbohydrate metabolism in the rat as influenced by 4-APP, an adenine analogue. Adult female rats were injected with 1 mg 4-APP/100 g body weight/day for 3 days. 4-APP evoked a marked enlargement of the liver with lipid droplets accumulation in hepatocytes. This was accompanied by a marked lowering of the liver glycogen content. Within 3 days 4-APP did not change serum glucose, insulin and free fatty acid concentration. Serum glycogenolytic activity studied in an in vitro system showed 7 times as high glucose releasing ability in 4-APP treated rats as that of the serum of control animals. 4-APP resulted also in a marked enlargement of the adrenal medulla and lowered adrenaline and noradrenaline concentrations in the gland. The possibility of an activation of glycogenolysis in the liver of 4-APP treated rats has been discussed.     

Plasma and adrenal corticosterone concentrations and liver glycogen content in premature mice at birth and during neonatal development

The concentrations of corticosterone in the plasma and adrenal glands and the content of glycogen in the liver were estimated from birth to day 6 after birth in surviving premature mice removed by Caesarean section on day 19 of pregnancy and submitted to reanimation during 30 min; the neonates were nourished by nursing mothers from 30 min after birth. A group of full-term newborns was removed by Caesarean section on day 20 of pregnancy and killed 30 min after reanimation. Premature mice were characterized by neonatal changes of three parameters used. The plasma corticosterone level reached a peak in the first 6 h after birth, then decreased until day 6. The adrenal corticosterone level did not vary significantly 30 min after birth, then decreased progressively until day 2. The liver glycogen content, very high on day 19 of pregnancy, increased 30 min after birth, then fell sharply until day 2. In full-term newborns removed by Caesarean section and killed 30 min after reanimation the plasma corticosterone level increased, whereas the adrenal corticosterone level and the liver glycogen content did not decrease. The adrenal gland of surviving premature mice was able to respond to the stress induced by the reanimation; the stimulation of glucocorticoid function was similar in both neonates.     

Effect of chronic CCl4 poisoning in the rat and of partial hepatectomy of the pathologically altered organ on glycogen levels of hepatocytes

A cytofluorometric study was made of total glycogen in rat liver cells in the norm and upon the chronic intoxication with CCl4. The liver cells were obtained from rats by means of intravital needle aspiration biopsy at the beginning of the experiment, after 3, and 6 months, and 1 month after partial hepatectomy of control and cirrhotic livers. Glycogen contents in liver cells were attributed to dry weight measured interferometrically. Upon the long-term chronic intoxication of rats with the hepatotropic poison the glycogen content increased by 1.4-2.5 times, and in some cells of cirrhotic livers even by 5-5.5 times compared to the normal level. 1 month after the resection both glycogen content and rat liver cell morphology were seen almost close to the normal. The data are discussed in terms of results earlier reported elsewhere on the increase of glycogen content in liver cells of patients with chronic hepatitis.     

Ultrastructure of thymus and liver following adrenalectomy and replacement adrenal hormone therapy in rats

Prior research in this laboratory has shown that dexamethasone, aldosterone, and epinephrine interact in regulating the activity of ornithine decarboxylase (EC 4.1.1.17, ODC) in rat thymus and liver. The three primary adrenal hormones were administered alone and in various combinations to adrenalectomized rats. Liver and thymus samples were removed, prepared for electron microscopy, and morphometric analysis of thymic micrographs was performed. It was found that both corticosteroids induced thymic lympholysis and that concurrent administration of epinephrine 'rescued' the lymphocytes. Observations of liver micrographs indicated that changes in liver glycogen deposition vary in response to the hormone treatment regimen. The liver response to a combination of the glucocorticoid and catecholamine was different from the response to the mineralocorticoid and catecholamine, which indicated that the liver response to the two steroids may be mediated via different mechanisms. Evidence is provided to support the conclusion that the influence of the adrenal gland on rat thymus and liver is not restricted to glucocorticoids but may also involve mineralocorticoids and catecholamines.     

Effect of bemythyl on carbohydrate metabolism in cirrhotic rat liver

Effect of actoprotector bemitil (2-ethylthiobenzimidazole hydrobromide) on glycogen content and activities of glycogen synthase, glycogen phosphorylase, and glucose-6-phosphatase was studied in cirrhotically altered rat liver. The contents of glycogen and its fraction were determined a cytofluorimetrically (Kudryavtseva et al., 1974). In cirrhosis, the total glycogen content in hepatocytes increases by nearly 3 times, while the amount of a stable fraction of glycogen rises by 7.5 times. Glucose-6-phosphatase activity fell to the level of 25% compare to the norm. Activities of glycogen synthase and glycogen phosphorylase in the cirrhotic liver did not differ from the norm. In cirrhotically altered liver, bemitil produced a decrease in the total glycogen content due to a decrease in glycogen synthase activity in an increase in glucose-6-phosphatase and glycogen phosphorylase activities. The above results suggest a favorable effect of bemitil on cirrhotic liver.     

Systemic effects of chronically administered methyl prednisolonate and methyl 17-deoxyprednisolonate

The systemic activities of methyl prednisolonate and methyl 17-deoxyprednisolonate (1) were studied in rats. Methyl 17-deoxyprednisolonate produced significant changes in the amount of sodium ion (decreased) and potassium ion (increased) in urine; however, methyl prednisolonate had no effect on electrolyte balance. Both methyl prednisolonate and methyl 17-deoxyprednisolonate had no effect on liver glycogen content, plasma corticosterone level and relative adrenal weight. In contrast, the parent compound prednisolone caused a significant decrease in liver glycogen content, plasma corticosterone level and relative adrenal weight.     

Inhibition of cortisone action in mice by heparin.

A single dose of heparin applied in a depot-form (Freund's incomplete adjuvant or Ca-phosphate gel) inhibits the effects of intraperitoneally injected cortisone on the lymphoid organs (thymus and spleen), on the peritoneal and peripheral lymphoid cell count and serum gamma globulin level as well as on the liver glycogen deposition in mice. The same dose of heparin did not influence the action of hydrocortisone measured on the thymic and spleen involution and liver glycogen content. The route of cortisone administration seems to be critical, as heparin shows no or only minor effects when cortisone is applied subcutaneously; moreover, the action of cortisone per se is more marked by subcutaneous than by intraperitoneal administration. The results suggest the hypothesis that heparin inhibits cortisone-cortisol conversion and this inhibition is mediated by macrophages.     

Cytofluorimetric study of the content of glycogen and its fractions in rat liver cells in the course of the 1st week of postnatal ontogeny]

A cytofluorometric study of the total glycogen and its fractions in rat liver cells using the fluorescent PAS reaction was made during 1--7 days of the postnatal development. It was established that glycogen content was small on the first two days of development. The glycogen content increases only on the third day after birth. The glycogen of the rat liver cells during a first week of the postnatal development is different from that detected in adult liver cells in two aspects: in 3 day old hepatocytes soluble and stable glycogen fractions are equal, while in adult rat liver cells the former makes 80--90%; during the first week of the postnatal development, the stable fraction of rat liver cell is more labile, while in the adult rat liver the soluble fraction of glycogen is more labiles.     

Protein biosynthesis in the rat liver in natural fluctuations of the steroid background

The results of the study of protein and RNA biosynthesis and inducation of glucose-6-phosphatase activity in the rat liver at natural (seasonal) fluctuations of the steroid background are presented. It is shown that the adrenal gland seasonal activation increases incorporation of precursors labeled (l14C-leucine and l14C-orotic acid) into total liver proteins and RNA and enhances glucose-6-phosphatase activity in the rat liver. The conclusion is drawn that the changes in the endogenous corticosteroid level have regulative significance for protein biosynthesis in the rat liver.     

Differential gene expression and regulation of type-1 angiotensin II receptor subtypes in the rat.

A simplified and sensitive method for measuring expression levels of type-1 angiotensin II (AT1) receptor subtypes, AT1A and AT1B, was established. The two receptor cDNAs were co-amplified and measured by polymerase chain reaction using primers based on the corresponding receptor subtype genes. Both AT1A and AT1B mRNAs were widely expressed in the rat tissues including adrenal gland, kidney, heart, aorta, lung, liver, testis, pituitary gland, cerebrum and cerebellum. AT1A mRNA was predominantly expressed in the rat tissues examined except adrenal gland and pituitary gland where AT1B mRNA was predominantly expressed. Sodium depletion did not change mRNA levels of AT1A and AT1B in the all tissues. However, both AT1A and AT1B mRNA levels in the heart and aorta were down-regulated by treatment with AT1 specific antagonist, TCV 116. In contrast, AT1B mRNA in the adrenal gland was mainly reduced by the treatment. These results suggest that the expression level of AT1B mRNA in the adrenal gland depends on the activity of the renin-angiotensin-aldosterone system (RAAS) and both receptor subtypes mediate contraction and hypertrophy of the smooth and cardiac muscles via the RAAS.     

The influence of hepatoprotector 2-ethylthiobenzimidazole hydrobromide (bemithyl) on the content of glycogen in cirrhotic rat liver hepatocytes located in various microenvironments

Using absorption and fluorescent cytophotometry methods, glycogen contents were studied in hepatocytes located in liver lobules and in hepatocytes, which make the general population of these cells in normal and cirrhotic rat liver. In cirrhosis, the content of glycogen in hepatocytes located in lobules obviously rises in comparison with the norm, but to a lesser degree, than in hepatocytes making the general population of these cells in cirrhotic liver. The content of glycogen in hepatocytes, located in lobules of pathologically changed liver in bemithyl treated rats, did not differ from the norm. At the same time, the glycogen content in hepatocytes, representing the general population of these cells in cirrhotically altered bemithyl injected rat liver, remained higher than in the norm. The data obtained indicate that distinctions in particular cell microinvironment, obviously present in cirrhotic liver, render essential influence on hepatocyte functional activity.     

Studies on the breakdown of glycogen in the lysosomes: the effects of hydrocortisone

The effects of hydrocortisone on newborn rat liver were studied by using biochemical assays, electron microscopy and quantitative morphometry. Hydrocortisone increased the number of lysosomes in the hepatocytes. Most of the lysosomes represented glycogen-containing autophagic vacuoles. The glucocorticoid also increased the activity of the liver glycogen-hydrolyzing acid glucosidase and the breakdown of glycogen inside lysosomes. The activity of the liver acid mannose 6-phosphatase was decreased. This may be related to the stimulation of autophagic mechanisms in the newborn rat hepatocytes.     

Activity of key enzymes of gluconeogenesis in the liver and corticosterone levels of the blood of thymectomized rats

Thymectomized rats have been studied with the aim to determine the activity of gluconeogenesis key enzymes (phosphoenol pyruvate carboxykinase, fructose-1.6-diphosphatase, glucose-6-phosphatase), the glycogen content in the liver, the corticosterone level in blood and electrolytes concentration in erythrocytes and blood plasma. The activity of glucose-6-phosphatase and the glycogen content in the liver as well as the corticosterone level in the rat blood are shown to diminish after thymectomy. Changes are found in the electrolytic composition of blood as well as in the activity of key enzyme of the pentose cycle in erythrocytes. The data obtained indicate that thymectomy in rats is followed by the pronounced biochemical shifts induced by the thymus hormone deficiency and disturbance of interrelations in the system of neuroendocrine regulation.     

Hormonal Regulation of Peripheral Benzodiazepine Binding Sites in Female Rat Adrenal Gland and Kidney

Abstract

The effect of hypophysectomy and hormonal replacement on the density of peripheral benzodiazepine binding sites (PBS) in rat adrenal gland and kidney was studied. In the adrenal gland, hypophysectomy caused a significant decrease of 3-fold in PBS density. In the kidney, in contrast, hypophysectomy did not affect PBS density. In the adrenal gland, adrenocorticotropic hormone (ACTH) administered to hypophysectomized rats caused a significant increase of more than 5-fold in PBS density compared to untreated hypophysectomized rats, and of more than 1.6-fold compared to intact rats. In contrast, the hormones pregnant mare serum gonadotropin (PMSG), diethylstilbestrol (DES), and hydrocortisone (HC), administered to hypophysectomized rats, failed to restore PBS density in the adrenal gland. In the kidney, HC administered to hypophysectomized rats caused an increase of 1.4-fold in PBS density compared to untreated hypophysectomized and intact rats. In contrast, the hormones ACTH, PMSG, and DES, administered to hypophysectomized rats, did not affect PBS density in the kidney. None of the hormones tested altered the equilibrium dissociation constant of PBS in either the adrenal gland or the kidney. These findings indicate that PBS density in rat adrenal gland and kidney is hormonally modulated.     

Regulation of glycogen metabolism in the adrenal gland. IV. The effect of insulin on glycogen synthetase, phosphorylase, and related metabolites

Previous studies have indicated that the glycogen content of adrenal glands of fasted rats can be depleted by insulin per se (Bindstein, E., Piras, R., and Piras, M. M., Endocrinology88, 223, 1971). In order to establish the mechanism of action of this hormone in the adrenal gland, the effect of insulin has been now investigated on glycogen synthetase (UDP-glucose: α-1,4 glucan α-4-glueosyl-transferase, EC 2.4.1.11), glycogen phosphorylase (α-1,4 glucan: orthophosphate glucosyl-transferase, EC 2.4.1.1) and metabolites related to these enzymes.Approximately 40% of total adrenal glycogen phosphorylase of fasted rats is in the active form, which increases to 75% 1 hr after insulin treatment (75 mU/100 g body wt). This conversion occurs without apparent large changes of 3′-5′ cyclic AMP. Concomitantly with the enzymatic change, the levels of glucose-6-P, UDP-glucose and P_i suffer alterations which favor an increased phosphorolytic activity during the first hour of insulin treatment. Glycogen synthetase, which did not change during this period, is converted to the glucose-6-P independent form during the 2–3 hr of treatment. This conversion is preceded by an increased glycogen synthetase phosphatase activity, which seems to follow an inverse relationship with the glycogen level.The results obtained suggest that the effect of insulin on the adrenal gland of fasted rats is glycogenolytic, that is, opposite to that described for this hormone in other normal tissues. The glycogen depletion, on the other hand, seems to set in motion the mechanism for glycogen synthetase activation, with the subsequent glycogen resynthesis.     

Effect of hydrocortisone on the phospholipid composition and activity of various enzymes of phospholipid metabolism in the nuclear membranes of the rat liver

It was shown that hydrocortisone injections markedly increase the total content of liver nuclear membrane phospholipids, the greatest increase being observed in the phosphatidyl choline level. It was found also that nuclear membranes contain phospholipid metabolism enzymes. The hormone-induced increase in the phospholipid content is accompanied by a marked decrease of the activity of phospholipase A2 (5.3 times against control), phospholipase C (9.3 times) and acyl-CoA: lysophosphatidylcholine transferase (2.5 times). The results obtained are suggestive of appreciable metabolic changes in nuclear membrane phospholipids caused by hydrocortisone which, in turn, may be due to hormonal activation of the genome.     

Effect of insulin on glycogen metabolism in isolated catfish hepatocytes

Insulin effect on carbohydrate metabolism in catfish hepatocytes consisted of a significant decrease of cell glycogen concentration both in the absence and in the presence of glucose in the medium. The hormone did not influence either the output of glucose from the cell or the intracellular glucose level. Experiments with radioactive glucose showed a very low uptake of the sugar by the hepatocytes; correspondingly the incorporation of radioactivity into glycogen was very low and not influenced by insulin. The glycogen content in catfish liver cells was influenced by the hormone in the opposite way to rat liver cells.     

Primary response mechanisms of the adrenal cortex in dogs to pain stress]

The adrenal cortex of dogs shows a drop in the glucocorticoid content 10--15 sec after the pain action in the presence of the free cholesterol level increase and its esterified form drop. The concentrations of hormones in the blood falls chiefly at the expense of protein bound hydrocortisone. The subsequent phase of the reaction (after 30--60 sec) is characterized by a considerable accumulation of the hormones by the gland. The level of free glucocorticoids significantly increases, the initial ratio of hydrocortisone and cortisone restores, and transcortin depot is filled up. The role of the adrenal and transcortine depot in realization of feedback mechanisms under stress is discussed.