Dexmedetomidine alleviates LPS/D-Gal-induced acute liver injury via up-regulation of LC3-II expression in mice / 生理学报

The aim of the present study was to investigate the effects of dexmedetomidine (DEX) on acute liver injury induced by lipopolysaccharide (LPS)/D-galactosamine (D-Gal) and the underlying mechanism. Male BALB/c mice were intraperitoneally injected with LPS/D-Gal to induce acute liver injury model, and pretreated with DEX or in combination with the autophagy inhibitor, 3-methyladenine (3-MA) 30 min before injection. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity, as well as myeloperoxidase (MPO) activity in liver tissue were determined with the corresponding kits. Serum tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) levels were determined by ELISA. The protein expression levels of LC3-II and P62 in liver tissue were determined by Western blot. Liver histopathological changes were detected by HE staining. The results showed that, compared with control group, LPS/D-Gal enhanced ALT and AST activity, increased TNF-α and IL-6 levels, as well as MPO activity, up-regulated LC3-II and P62 protein expression levels, and significantly induced pathological damage in liver tissue. DEX reversed the above changes in the LPS/D-Gal group, whereas these protective effects of DEX were blocked by 3-MA. The above results suggest that DEX alleviates LPS/D-Gal-induced acute liver injury, which may be associated with the up-regulation of LC3-II protein expression and the activation of autophagy.

Edaravone protects endotoxin-induced liver injury by inhibiting apoptosis and reducing proinflammatory cytokines

Studies have shown that edaravone may prevent liver injury. This study aimed to investigate the effects of edaravone on the liver injury induced by D-galactosamine (GalN) and lipopolysaccharide (LPS) in female BALB/c mice. Edaravone was injected into mice 30 min before and 4 h after GalN/LPS injection. The survival rate was determined within the first 24 h. Animals were killed 8 h after GalN/LPS injection, and liver injury was biochemically and histologically assessed. Hepatocyte apoptosis was measured by TUNEL staining; proinflammatory cytokines [tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)] in the liver were assayed by ELISA; expression of caspase-8 and caspase-3 proteins was detected by Western blot assay; and caspase-3 activity was also determined. Results showed that GalN/LPS induced marked elevations in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Edaravone significantly inhibited elevation of serum AST and ALT, accompanied by an improvement in histological findings. Edaravone lowered the levels of TNF-α and IL-6 and reduced the number of TUNEL-positive cells. In addition, 24 h after edaravone treatment, caspase-3 activity and mortality were reduced. Edaravone may effectively ameliorate GalN/LPS-induced liver injury in mice by reducing proinflammatory cytokines and inhibiting apoptosis.

Protective effect of Pterocarpus santalinus Linn, on D-galactosamine induced liver damage

The present study was carried out to investigate the hepatoprotective effect of two doses of the extract of Pterocarpus santalinus Linn, on acute hepatotoxicity induced in Wistar albino rats by a single dose of D-galactosamine [400 mg/kg]. Suspensions of methanolic extract of heartwood of Pterocarpus santalinus [200 mg/kg and 400 mg/kg] in 0.3% carboxy methyl cellulose [CMC] were administered p.o. to experimental animals according to the protocol followed by the i.p. administration of a single dose of hepatotoxin. Hepatoprotective activity was monitored by estimating aspartate amino transferase [ASAT, GOT], alanine amino transferase [ALAT, GPT], alkaline phosphatase [ALP], totat bilirubin [TB], lactate dehydrogenase [LDH] total cholesterol [TC], triglycerides [TGL], albumin, total protein [TP] levels and histopathological changes in the livers of P. santalinus - treated and untreated groups of animals. The results clearly indicated that the extract of P. santalinus significantly reduced the acute elevation of serum transaminases and alteration of other biochemical parameters induced by hepatotoxin, and alleviated the degree of liver damage at 24 hrs. after the intraperitoneal administration of the hepatotoxins. Silymarin [25 mg/kg], a known hepatoprotective drug was used for comparison. The results were supported by histopathological studies of liver samples showing regeneration of hepatocytes in treated animals. Based on the results obtained in the present investigation, it can be concluded that Pterocarpus santalinus exerts hepatoprotective activity and may serve as a useful adjuvant in several clinical conditions associated with liver damage

Protective effects of Indigofera tinctoria L. against D-Galactosamine and carbon tetrachloride challenge on 'in situ' perfused rat liver.

The effect of pre-treatment with Indigofera tinctoria (IT) extract against the toxicity of D-Galactosamine (D-GalN) and carbon tetrachloride (CCl4) during 'in situ' perfusion of the liver for 2 hr was studied in rats. Release of LDH and levels of urea in the liver effluent perfusate, was studied and the rate of bile flow was monitored. Perfusion with D-Galactosamine (5 mM) or carbon tetrachloride (0.5 mM) resulted in increased LDH leakage, decreased urea levels in the liver effluent and reduction in bile flow. IT pretreatment (500 mg/kg body weight) in vivo ameliorated D-GalN and CCl4 induced adverse changes towards near normalcy and thereby indicates its hepatoprotective effects in rats.

Effect of Indigofera tinctoria Linn on liver antioxidant defense system during D-galactosamine/endotoxin-induced acute hepatitis in rodents.

Effects of pre-treatment with the alcoholic extract of I. tinctoria (500 mg/kg body wt/day, p.o. for 21 days) on liver antioxidant defense system during acute hepatitis induced by D-galactosamine (D-GalN)/endotoxin (LPS extracted by phenol water method from E. coli serotype 0111.B4; 300 mg and 30 micrograms/kg body wt/day, i.p., 18 hr before the assay) were investigated on the activities of enzymic antioxidants such as superoxide dismutase, catalase, glutathione peroxidase and glutathione-s-transferase, and levels of total reduced glutathione in the liver of normal and experimental groups of male albino rats. Since lipid peroxidation and associated membrane damage is a key feature of D-galN/LPS-induced liver injury, the levels of lipid peroxides, was estimated and used as an index of oxidative stress. D-GalN/endotoxin-induced hepatic damage was manifested by a significant decrease in the activities of antioxidant enzymes, decreased glutathione levels and increased levels of lipid peroxides. I. tinctoria pre-treated rats showed considerable protection against D-galN/endotoxin, induced oxidative stress as evidenced by a significant increase in the activities of all the antioxidant enzymes studied and significant decrease in the levels of lipid peroxides. Results indicate that pretreatment with I. tinctoria extract in rats is very effective in reducing D-GalN/endotoxin-induced oxidative stress suggesting an antioxidant effect.

Silymarin mediated differential modulation of toxicity induced by carbon tetrachloride, paracetamol and D-galactosamine in freshly isolated rat hepatocytes.

Influence of silymarin on the modulation of hepatotoxicity induced by carbon tetrachloride (CCl4), paracetamol (AAP) and D-galactosamine (GalN) was examined in freshly isolated rat hepatocytes in suspension culture. While the three hepatotoxicants produced differential biochemical response, the flavone was able to restore biochemical alterations only in hepatocytes exposed to CCl4 and AAP induced toxicity. Silymarin at 0.4 mM was able to counteract lipid peroxidation and enzyme leakage induced by 3 mM CCl4 The flavone also offered protection by more than 60% in hepatocytes isolated from PB pre-treated rats where CCl4 at 2 mM produced enhanced toxicity over hepatocytes isolated from untreated control rats. Similarly, the flavone protected AAP-induced GSH depletion by more than 75% in hepatocytes isolated from untreated and 3-methylcholanthrene treated rats. However, instead of protecting GalN-induced depletion of UDP-glucuronic acid in hepatocytes, the flavone itself reduced the nucleotide content very rapidly compared to GalN, the later exerted time dependent effect. Silymarin at 0.4 mM reduced UDPGA by more than 60%. The results suggested that freshly isolated hepatocytes in suspension culture offer a simple and convenient method for evaluation of pharmaceutical agents of antihepatotxic potentials against various hepatotoxicants.

Differential biochemical response of freshly isolated rat hepatocytes to paracetamol, carbon tetrachloride and D-galactosamine toxicity.

Differential response of freshly isolated rat hepatocytes to paracetamol (acetaminophen, AAP), carbon tetrachloride (CCl4) and D-galactosamine (GalN) was examined. The viability of the cells in suspension culture was not altered for 4 hr when incubated in Hank's balanced salt solution (HBSS) supplemented with 4.2 mM NaHCO3, 10 mM HEPES buffer and 0.5% bovine serum albumin. AAP induced time and dose dependent depletion of GSH as an early manifestation of AAP toxicity. Hepatocytes exposed to AAP exhibited lower lactate dehydrogenase (LDH) activity released into the medium than in controls. This was due to the interaction of a reactive metabolite of AAP, i. e. N-acetyl p-benzoquinoneimine (NAPQI) with cell proteins. Hepatocytes isolated from rats pretreated with 3-methylcholanthrene expressed higher sensitivity to AAP toxicity at least by a factor of 5. Furthermore, AAP-induced toxicity was not found to be related to any lipoperoxidative stress. CCl4 on the other hand elicited a highly lipoperoxidative response in hepatocytes and consequent leakage of cellular enzymes with lengths of incubation. Again the sensitivity of the response to CCl4 was enhanced remarkably in hepatocytes isolated from phenobarbital- pretreated rats; LDH leakage increased by 3-fold and thio-barbituric acid reactive substances by 25-fold. Unlike the two toxicants, galactosamine depleted UDP-glucuronic acid in a concentration and time-related manners. The differential biochemical response of hepatocytes to three hepatotoxicants investigated may prove useful as rapid in vitro screen for selection of compounds of hepatoprotective potentials.

Effects of silymarin on UDP-glucuronic acid and glucuronidation activity in the rat isolated hepatocytes and liver in relation to D-galactosamine toxicity.

Influence of silymarin on UDP-glucuronic acid (UDPGA) and glucuronidation activity of freshly isolated rat hepatocytes in suspension and in rat liver in vivo was examined. Viability of the hepatocytes (> 85%) was not altered in Hank's balanced salt solution at least for 4 hr at 37 degrees C under oxygen. Silymarin at 0.4 mM depleted UDPGA by more than 60% at the end of 4 hr of incubation, the fall in nucleotide pool was rapid and concentration (0.1-0.4 mM)-dependent. The rate of glucuronidation of 3-OH- benzo(a)pyrene (3-OH-BP) determined simultaneously was also reduced significantly; silybin being 3-times more effective than silymarin. Combination of flavonoids with D-galactosamine (GalN) further attenuated the glucuronidation functions of the cells. The flavonoids also offered strong inhibition of UDP-glucose dehydrogenase (UDP-GDH) activity in the liver cytosolic fraction while the activity in hepatocytes was not affected even after 4 hr of incubation. Interestingly, the GalN- induced strong inhibition of UDP-GDH in isolated hepatocytes was completely abolished by flavonoids. Decrease in UDPGA appeared neither due to the activation of UDPGA-pyrophosphatase activity nor to the inhibition of UDP-GDH activity in hepatocytes. Further, the flavonoids also inhibited hepatic UDP-glucuronyltransferase activity towards 3-OH-BP (UGT) both in vitro and in intact cells. On the contrary, silymarin administered (70 mg/kg body wt; i.p.) to rats for 3 hr increased the hepatic UDPGA by 2-fold while GalN (400 mg/kg body wt) reduced the nucleotide content to 50% of control. Coadministration of silymarin and GalN restored the UDPGA content significantly while the activities of UDP-GDH and UGT were comparable to the untreated control. The results indicated that silymarin elicits differential effects on the rate of glucuronidation and contents of UDPGA in the isolated rat hepatocytes and in liver. The flavonoid counteracted D-GalN-induced lowering of UDPGA presumably by relieving UDP-GDH of in vivo inhibition affected by GalN-metabolite.