Effect Of D-galactosamine Research Articles

New benzoic acid glycosides from Sophora flavescens

Two new benzoic acid derivatives, sophophenoside A (1) and sophophenoside B (2), were isolated from Sophora flavescens. Their structures were elucidated by detailed spectroscopic analysis and chemical methods. Compounds 1 and 2 were assayed for their hepatoprotective activity on the cytotoxic effect of D-galactosamine on HL-7702 cells, and compound 1 exhibited a moderate hepatoprotective activity at a concentration of 10 μM.

Effects of anti-ulcer agents on ethanol-induced gastric mucosal lesions in D-galactosamine-induced hepatitis rats.

Patients with hepatic injury have an increased incidence of gastric ulcers and erosions. In this study, the effect of D-galactosamine(GalN)-induced hepatitis on ethanol-induced gastric mucosal lesions and the protective effect of anti-ulcer agents in rats were examined. Subcutaneous injection of GalN (1 g/kg) remarkably increased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities suggesting induction of hepatic injury. Gastric mucosal lesions induced by ethanol were significantly aggravated in GalN-induced hepatitis rats. Orally administered ecabet (CAS 86408-72-2; 20-200 mg/kg) dose dependently inhibited ethanol-induced gastric mucosal lesions in GalN-induced hepatitis rats. Sucralfate (CAS 54182-58-0) tended to inhibit the gastric mucosal lesions at a dose of 200 mg/kg but teprenone (CAS 6809-52-5), cimetidine (CAS 51481-61-9) and rebamipide (CAS 90098-04-7) had little effect. All anti-ulcer agents had no effect on the serum ALT and AST activities increased by GalN pretreatment. These results indicate that the gastric mucosa of GalN-induced hepatitis rats is more susceptible to injury induced by luminal irritants such as ethanol. Ecabet potently inhibited gastric mucosal lesions suggesting its clinical utility for the gastric mucosal damage in patients with hepatic injury.

Modulation of Spontaneous and Lipopolysaccharide-Induced Nitric Oxide Production and Apoptosis by D-Galactosamine in Rat Hepatocyte Culture: The Significance of Combinations of Different Methods

ABSTRACTApoptotic markers and signals produced by xenobiotics as hepatotoxic D-galactosamine (D-GalN) and lipopolysaccharide (LPS) are extensively investigated in vivo. The contribution of various cells and factors as nitric oxide (NO) in mediating hepatocyte apoptosis in a rat model of systemic endotoxemia was reported. Therefore, the aim of the present work was to study the in vitro effect of D-GalN on nonstimulated or LPS-treated rat hepatocytes in culture and the potential involvement of NO in this process. Our results showed that the spontaneous and LPS-induced NO production was completely blocked by D-GalN during 0 to 24 hours. However, D-GalN slightly enhanced NO production during 24 to 48 hours. D-GalN was more potent to induce hepatocyte apoptosis and necrosis during 24 to 48 than 0 to 24 hours as evidenced morphologically (Annexin V/propidium iodide staining) and biochemically (caspase-3-like activity, alanine-aminotransferase leakage, MTT test). Interestingly, D-GalN treatment suppressed mitochondrial cytochrome C release throughout the study. LPS addition to D-GalN considerably aggravated apoptotic/necrotic markers only during 0 to 24 hours. Surprisingly, a share of apoptotic cells was distinctly lower after LPS + GalN treatment than after LPS alone during 0 to 24 hours, while 24- to 48-hour incubation produced massive apoptotic/necrotic hepatocytes. It may be concluded that there is a significant modulation of NO production by D-GalN. Because the role of NO is only partly decisive in the apoptotic/necrotic events, and considering the fraction of the cells completing apoptosis while others that turn toward necrosis (aponecrosis), caution should be exercised in apoptosis data interpretation and combinations of different test methods should be applied.

The enhancing action of d-galactosamine on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophage cells

The effect of d-galactosamine ( d-GalN) on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells was examined. d-GalN augmented the production of NO, but not tumor necrosis factor (TNF)-α in LPS-stimulated RAW 264.7 cells. Pretreatment of d-GalN augmented the NO production whereas its post-treatment did not. d-GalN augmented the NO production in RAW 264.7 cells stimulated with either TNF-α and interferon-γ. The augmentation of LPS-induced NO production by d-GalN was due to enhanced expressions of an inducible type of NO synthase mRNA and proteins. Intracellular reactive oxygen species (ROS) were exclusively generated in RAW 264.7 cells stimulated with d-GalN and LPS. Scavenging of intracellular ROS abrogated the augmentation of NO production. It was therefore suggested that d-GalN might augment LPS-induced NO production through the generation of intracellular ROS.

Effect of D-galactosamine on mitochondria and prevention from galactosamine - induced injury by S-adenosylmethionine in hepatocyte culture

Effect of D-galactosamine on mitochondria and prevention from galactosamine - induced injury by S-adenosylmethionine in hepatocyte culture

Hepatocyte specific long lasting inhibition of protein N-glycosylation by D-galactosamine

The effect of D-galactosamine on protein N-glycosylation was studied in rat hepatocyte primary cultures for α 1-antitrypsin (three complex type oligosaccharide chains) and α 1-acid glycoprotein (six complex type oligosaccharide chains). D-Galactosamine at a concentration of 4 mM inhibited partially de novo N-glycosylation leading to the formation of α 1-antitrypsin lacking one to two and of α 1-acid glycoprotein lacking one to five of its carbohydrate side chains. In addition D-galactosamine interferred with oligosaccharide processing, leading to the formation of some carbohydrate side chains remaining in an endoglucosaminidase H sensitive, i.e., not completely processed, form. D-Galactosamine impaired the secretion of α 1-antitrypsin and of α 1-acid glycoprotein but did not inhibit the secretion of the unglycosylated albumin. The inhibitory effect of d-galactosamine on de novo glycosylation as well as on oligosaccharide processing lasted for at least 24 h after it had been removed from the cells. d-Galactosamine impaired the glycosylation of α 1-antitrypsin only in hepatocytes, but not in human monocytes. Furthermore, d-galactosamine did not impair the N- and O-glycosylation of interleukin-6 in human monocytes and in MRC 5 fibroblasts. The results indicate that the effect of d-galactosamine on protein glycosylation is restricted to d-galactosamine metabolizing hepatocytes and is not exerted by the drug itself but by its metabolites.

Effect of D-galactosamine on blood clearance of 99mTc-phytate in rats.

The effect of D-galactosamine (GalN) on the blood clearance of 99mTc-phytate (99mTc-P) in rats was examined, and the blood clearance test of 99mTc-P was compared with the cases of serum transaminase and bilirubin test. Serum transaminase and bilirubin levels in rats increased dose-dependantly after GalN administration. The disappearance rate of 99mTc-P from blood decreased with the increase in dose of GalN and with the passage of time after the GalN administration. Changes of the blood clearance of 99mTc-P after GalN treatment in rats may be influenced by the disorder in the hepatocytes and the alteration of the liver reticuloendothelial system phagocytic function. The blood clearance test of 99mTc-P in rats showed a sensitive reaction for the acute hepatic dysfunction induced by GalN equally to or higher than the serum transaminase and bilirubin test.

Effect of D-galactosamine on blood clearance of 99mTc-phytate in dogs.

The effect of D-galactosamine (GalN) on the blood clearance of 99mTc-phytate (99mTc-P) in dogs was examined, and the blood clearance test of 99mTc-P was compared with the cases of the serum transaminase and bilirubin test. Serum transaminase and bilirubin levels in dogs increased dose-dependently after GalN administration, and the degree of increase in these parameters was much higher than the cases in rats. The disappearance rate of 99mTc-P from blood in dogs decreased with the increase in dose of GalN and with the passage of time after the GalN administration. Changes of the blood clearance of 99mTc-P after GalN treatment in dogs may be influenced by the disorder in the hepatocytes. The blood clearance test of 99mTc-P in dogs showed a sensitive reaction for the acute hepatic dysfunction induced by GalN equally to the serum transaminase and bilirubin test.

D-galactosamine-induced liver injury: a rat model to study the heterogeneity of the oligosaccharide chains of alpha 1-acid glycoprotein.

The effect of D-galactosamine on the structure of the glycan moiety of alpha 1-acid glycoprotein was studied throughout a nine days experiment. It was shown that: D-galactosamine led to an alteration of the Concanavalin A crossed immunoelectrophoresis pattern and to a decreased sialic acid content of alpha 1-acid glycoprotein. The undersialylation of alpha 1-acid glycoprotein was not linked to a change in the relative ratio of various Concanavalin A forms. At the end of the experiment (9 days after galactosamine injection), the Concanavalin A non-reactive forms of alpha 1-acid glycoprotein remained elevated whereas alanine transaminase activity, total protein and alpha-acid glycoprotein had returned to a control level. D-galactosamine-treated rats seem to be a suitable model for the study of the very fast cyclic modulations of the synthesis of the glycan moiety of glycoproteins.

Effect of d-galactosamine in vitro on [U- 14C]palmitate oxidation, triacylglycerol synthesis and secretion in isolated hepatocytes

Isolated rat hepatocytes were used to study in vitro effects of 10 mM d-galactosamine (GalN) on hepatic fatty acids metabolism. (1) At this concentration, membrane integrity and biochemical competence (i.e., gluconeogenesis and ureogenesis) remained unaffected. (2) Protein synthesis and secretion, as measured by the incorporation of [U- 14C]leucine into total and medium protein, was significantly inhibited when incubated for more than 2 h. (3) GalN activated the incorporation of [U- 14ClpaImitate into triacylglycerols and depressed its utilization in the formation of labelled ketone bodies and 14CO 2. (4) Hepatocytes isolated from fasted rats exposed to GalN in vitro did not show any variation in prelabelled triacylglycerol secretion. (5) GalN induced a rapid inhibition of prelabelled triacylglycerol secretion by hepatocytes isolated from fed rats in which this secretion occurred to a larger extent than in hepatocytes isolated from fasted rats. The data reported here suggest that GalN induces a rise of triacylglycerol synthesis by inhibiting the palmitate oxidation pathway and a decrease of triacylglycerol secretion through an early derangement of the secretory pathway.

The effect of D-galactosamine on LCAT secretion and ultrastructure of isolated rat hepatocytes.

The effect of D-galactosamine on secretory activity and morphology of isolated rat hepatocytes was investigated: Galactosamine was found to reduce the secretion of lipoproteins (as indicated by the release of free cholesterol and triacylglycerol) as well as the secretion of lecithin: cholesterol acyltransferase (LCAT) and [14C]-labelled proteins from the isolated cells. The secretion of LCAT was inhibited much more than that of the other secretory products studied. Transmission electron microscopy revealed that galactosamine induced morphological changes in RER, mitochondria and nucleoli. The most striking feature of galactosamine-treated hepatocytes, however, was the appearance of swollen lysosomes. Some of these organelles measured up to 3 mumicrometer in diameter. Uridine did not abolish the effect of galactoosamine upon the secretory activity of hepatocytes. The most conspicuous ultrastructural feature in cells that had been incubated with both uridine and galactosamine was the appearance of large amounts of glycogen. The possibility that galactosamine inhibits glycogenolysis is discussed. The rather selective effect of galactosamine on LCAT secretion suggests the use of this compound for the study of the interrelationship between LCAT and lipoprotein secretion.