Effect Of Galactosamine Research Articles

Effect of galactosamine, an inhibitor of hepatic protein synthesis, on endotoxin-induced fever and pyrogenic tolerance.

Effect of galactosamine, an inhibitor of hepatic protein synthesis, on endotoxin-induced fever and pyrogenic tolerance.

Sandfly midgut lectin: effect of galactosamine on Leishmania major infections.

Galactosamine, which has been shown in vitro to specifically inhibit sandfly midgut lectin activity, was fed to Phlebotomus duboscqi females with blood containing promastigotes of Leishmania major. Non-inhibitory sugar, galactose, was added in controls. For two strains of L. major (LV 561 and Neal-P), galactosamine substantially enhanced the establishment of infection in the sandfly posterior midgut and significantly increased parasite loads after defaecation, but did not affect anterior migration of Leishmania. On day 3 post-infection, most infections in galactosamine-fed sandfly groups (92% of LV 561 and 100% of Neal-P) were found in the ectoperitrophic space of the posterior midgut, whereas most infections in the galactose-fed groups of sandflies (85% in LV 561 and 96% in Neal-P) were restricted to the peritrophic sac. On day 9, however, the proportion of infections colonizing the stomodeal valve was similar in both dietary groups of sandflies for both strains of L. major. The addition of galactosamine prevented the decrease of parasite loads which occurred in controls between days 3 and 6 post-infection. On days 6 and 9, heavy infections were observed almost exclusively in galactosamine-fed females. Differences between groups were more pronounced for the Neal-P strain, which normally developed poorly in sandflies. Morphology of L. major LV 561 was not affected by galactosamine supplement: the lengths of parasite body and flagellum were similar in both sandfly groups. Two hypotheses are considered for the role of sandfly midgut lectin in Leishmania development in the vector midgut. One proposes that sandfly lectin kills Leishmania promastigotes, the other assumes that lectin blocks LPG-mediated binding of promastigotes to sandfly midgut microvilli.

Effect of galactosamine on adenine and uracil nucleotide levels in isolated hepatocytes of young and old rats.

The aging process is associated with changes at cellular and tissue levels which may lead to deterioration of organ functions. Under basal conditions the majority of hepatic functions is well compensated in aging, however, under exogenous or endogenous stimulation age-related decrease in liver functional capacity might become evident.1 We found previously2 that upon incubation with galactosamine (GalN) protein synthesis in hepatocytes isolated from old rats was suppressed almost twice as much as in hepatocytes from young animals. In the present investigation we looked at nucleotide content of control and aminosugar-exposed hepatocytes of both age groups.KeywordsYoung AnimalNucleotide ContentAdenylate Energy ChargeIsolate HepatocyteIsolate Liver CellThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Galactosamine hepatotoxicity: Effect of galactosamine on glutathione resynthesis in rat primary hepatocyte cultures

The effect of galactosamine on the resynthesis of glutathione in rat primary hepatocyte cultures was investigated. Cultured rat hepatocytes were treated with galactosamine (4 m m) 1.5 hr prior to, concurrent with, or 1.5 hr after cell attachment; total cellular glutathione was then measured over time. Addition of galactosamine at any of these times suppressed methionine-enhanced glutathione resynthesis in the cultures after a lag period of about 120 min. The lag period was not due to slow uptake of galactosamine by the cultured cells, since cellular UTP levels fell to less than 10% of controls within 60 min, a time frame comparable to that observed in vivo. Neither was the lag period a result of interference with cellular uptake of methionine or with conversion of methionine to cysteine, since the phenomenon was observed regardless of whether methionine or cysteine was used to promote glutathione resynthesis. Addition of uridine, which protects against galactosamine hepatotoxicity in vivo by replenishing hepatic UTP levels, did not prevent the suppression of glutathione resynthesis. The data indicate that (a) galactosamine inhibits the time-dependent resynthesis of glutathione in primary hepatocyte cultures, (b) a lag period exists for this response, and (c) this effect is not directly related to depletion of cellular UTP stores.

The Effect of Galactosamine on Rat Liver Cytochrome P-450 Activities

The effect of galactosamine on hepatic drug metabolizing activities was examined in rats. In the microsomal fraction, the contents of cytochrome P-450 (P-450) and cytochrome b5 (b5) and the activity of NADPH-cytochrome c reductase (reductase) were examined for 7 days after galactosamine administration. In addition, substrate metabolizing activities in damaged microsomes were examined using four substrates: aminopyrine, aniline, benzo(a)pyrene (B(a)P) and 7-ethoxycoumarine (7-EC). The contents of P-450 and b5 and the activity of reductase showed a minimal value after 3 days of galactosamine administration and then gradually increased, reaching to the control level after 7 days. All four substrate metabolizing activities showed a similar response as the content of P-450, but the decrement among the four activities was not uniform. The activities of B(a)P hydroxylation and 7-EC deethylation were more impared than those of aminopyrine demethylation and aniline hydroxylation. This nonuniformity was clear on the activity based on P-450. This result suggested that galactosamine disturbed the population of multiple P-450 subtypes, and each P-450 subtype was damaged to the various extent by galactosamine administration.

Studies on the inhibition of glycogenolysis by D-galactosamine in rat liver hepatocytes

Effect of galactosamine on glycogenolysis was studied in isolated hepatocytes. It was found that addition of galactosamine strongly inhibited glycogenolysis in normal hepatocytes. Galactosamine-inhibited glycogenolysis was not stimulated by epinephrine or glucagon. This inhibition was specific as no such inhibition was observed with galactose, 2-deoxy-glucose or glucosamine. The glucagon-stimulated cyclic AMP formation in galactosamine-treated hepatocytes was the same as in normal cells; Glc-1-P and Glc-6-P did not accumulate nor was lactate formation enhanced. The glucose production by hepatocytes from regenerating liver was only slightly inhibited by galactosamine and glucagon addition stimulated glycogenolysis in the presence of the amino sugar.

The Effect of Galactosamine on the Activity of Lysosomal Peptidehydrolases of the Liver Depending on the Age of Rats

In order to elucidate the role of lysosomes during the development of hepatitis induced by D-galactosamine, the activities of cathepsin A, cathepsin D, and acid carboxypeptidase are measured in the liver after administration of a single dose of 375 mg D-galactosamine HCI per kg body weight This dose is able to induce hepatitis in young and adult, but not in newborn rats up to 4 weeks of age. Concommitantly, changes in lysosomal enzyme activities are not observed in the livers of newborn rats but in those of young and adult rats.