Acetaminophen-induced liver injury and oxidative stress: protective effect of propofol:

Midazolam Ameliorates Acute Liver Injury Induced by Carbon Tetrachloride via Enhancing Nrf2 Signaling Pathway

Oxidative stress contributes greatly to initiation and progression of liver injury. Activation of nuclear-factor erythroid 2-related factor 2 (Nrf2) has been considered as an attractive strategy for preventing and treating the oxidative damage related to liver injury. This study aimed to find an efficacious agent to activate Nrf2/HO-1 signaling pathway from clinically used therapeutic agents and to characterize the usefulness for preventing and treating CCl₄-induced acute liver injury. For this purpose, a series of clinically used therapeutic agents were collected and their activation potentials on Nrf2 were assayed by using 293T-Nrf2-luc cell line. Among all tested therapeutic agents, midazolam was found with good Nrf2 activation effect and this agent could significantly ameliorate CCl₄-induced damage to HepG2 cells. In vivo animal tests showed that pretreatment with midazolam reduced the liver pathological tissue damage and the serum levels of ALT and AST in CCl₄-induced liver injury mice. Further investigations showed that midazolam could strongly up-regulate the expression of both Nrf2 and HO-1 in the mice liver, accompanied by increasing of the levels of antioxidant enzyme SOD and reducing the production of MDA, as well as reducing the pro-inflammatory cytokines (IL-6, TNF-α) secretion. Collectively, our results clearly demonstrate that midazolam can ameliorate CCl₄-induced acute liver injury and oxidative stress via activating the Nrf2 signaling pathway.

Neonatal Anesthesia and Oxidative Stress

Neonatal anesthesia, while often essential for surgeries or imaging procedures, is accompanied by significant risks to redox balance in the brain due to the relatively weak antioxidant system in children. Oxidative stress is characterized by concentrations of reactive oxygen species (ROS) that are elevated beyond what can be accommodated by the antioxidant defense system. In neonatal anesthesia, this has been proposed to be a contributing factor to some of the negative consequences (e.g., learning deficits and behavioral abnormalities) that are associated with early anesthetic exposure. In order to assess the relationship between neonatal anesthesia and oxidative stress, we first review the mechanisms of action of common anesthetic agents, the key pathways that produce the majority of ROS, and the main antioxidants. We then explore the possible immediate, short-term, and long-term pathways of neonatal-anesthesia-induced oxidative stress. We review a large body of literature describing oxidative stress to be evident during and immediately following neonatal anesthesia. Moreover, our review suggests that the short-term pathway has a temporally limited effect on oxidative stress, while the long-term pathway can manifest years later due to the altered development of neurons and neurovascular interactions.

PCAF fine-tunes hepatic metabolic syndrome, inflammatory disease, and cancer

The P300/CBP‐associating factor (PCAF), a histone acetyltransferase, is involved in metabolic and pathogenic diseases, particularly of the liver. The effects of PCAF on fine‐tuning liver diseases are extremely complex and vary according to different pathological conditions. This enzyme has dichotomous functions, depending on differently modified sites, which regulate the activities of various enzymes, metabolic functions, and gene expression. Here, we summarize the most recent findings on the functions and targets of PCAF in various metabolic and immunological processes in the liver and review these new discoveries and models of PCAF biology in three areas: hepatic metabolic syndrome, inflammatory disease, and cancer. Finally, we discuss the potential implications of these findings for therapeutic interventions in liver diseases.

Comparative Protective Effects of N-Acetylcysteine, N-Acetyl Methionine, and N-Acetyl Glucosamine against Paracetamol and Phenacetin Therapeutic Doses-Induced Hepatotoxicity in Rats

BACKGROUND AND AIMS

Both paracetamol (PA) and phenacetin (PH) are analgesic and antipyretic agents. Part of phenacetin therapeutic activity is attributed to its metabolism into paracetamol. Paracetamol causes direct hepatic oxidative stress damage. The present study aimed to investigate the possible damaging effects of both PA and PH, when used in therapeutic doses, on rat liver and to compare the antioxidant and hepatoprotective effects of N-acetylcysteine (NAC), N-acetyl-methionine (NAM), and N-acetylglucosamine (NAG) against PA- or PH-induced hepatic damage.

METHODS

90 male Wistar albino rats (120-140 gm) were undertaken, categorized randomly into 9 groups of 10 rats each, and administered by gavage for 2 weeks with DMSO 1% (controls), PA, PA+NAC, PA+NAM, PA+NAG, PH, PH+NAC, PH+NAM, and PH+NAG. Biochemical assays of malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH), total thiols, and alpha-fetoprotein (AFP) in liver homogenates and serum assays of ALT, AST, 8-hydroxy guanine (8-OH-Gua), and AFP were done. Also histopathological examinations of liver tissues in various groups were done.

RESULTS

PA and PH cause significant increase in hepatic levels of MDA, NO, and AFP and serum ALT, AST, and 8-OH-Gua levels, with significant decrease in hepatic GSH and total thiols. NAG and NAC significantly improve the PA- and PH-induced hepatic and blood, biochemical, and histopathological disturbances, respectively.

CONCLUSIONS

Both PA and PH induce oxidative stress in rat liver within their therapeutic doses. NAG and NAC in pharmacological doses can antagonize the oxidative damaging effect of both PA and PH.

Propofol reduces liver dysfunction caused by tumor necrosis factor-α production in Kupffer cells

PURPOSE

The present study, conducted in rats, investigated whether propofol attenuates lipopolysaccharide (LPS)-triggered liver dysfunction via regulation of tumor necrosis factor (TNF)-α production in activated Kupffer cells.

METHODS

Rats received LPS (500 μg/kg) under Urethane™ sedation (1 g/kg) in combination with propofol (5 mg/kg/h) or Intralipid™ from 1 h before to 6 h after LPS administration. Some rats were treated with 10 mg/kg gadolinium chloride (GdCl3) to induce Kupffer cell depletion. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), TNF-α mRNA and protein expression, caspase-3 activation and apoptosis were evaluated in hepatocytes. Immunofluorescence staining revealed expression of the pan-macrophage marker CD68 as well as TNF-α in Kupffer cells.

RESULTS

ALT and AST serum levels increased approximately four-fold in LPS-exposed rats compared with Intralipid™-treated rats at 6 h after LPS administration, whereas propofol and GdCl3 reduced the LPS-induced increases. LPS simultaneously augmented TNF-α expression in Kupffer cells, followed by increased caspase-3 activity and apoptosis in hepatocytes. Immunofluorescence staining and immunoblotting assay showed that TNF-α expression in Kupffer cells was inhibited by propofol and GdCl3, resulting in a reduction of caspase-3 activity and apoptosis in LPS-treated rat hepatocytes.

CONCLUSIONS

Propofol (5 mg/kg/h) attenuated LPS-triggered liver dysfunction via inhibition of TNF-α production in activated Kupffer cells. These results suggest that propofol is capable of inhibiting inflammation-induced liver dysfunction in vivo.

Ferulic acid prevents liver injury and increases the anti-tumor effect of diosbulbin B in vivo

The present study is designed to investigate the protection by ferulic acid against the hepatotoxicity induced by diosbulbin B and its possible mechanism, and further observe whether ferulic acid augments diosbulbin B-induced anti-tumor activity. The results show that ferulic acid decreases diosbulbin B-increased serum alanine transaminase/aspartate transaminase (ALT/AST) levels. Ferulic acid also decreases lipid peroxide (LPO) levels which are elevated in diosbulbin B-treated mice. Histological evaluation of the liver demonstrates hydropic degeneration in diosbulbin B-treated mice, while ferulic acid reverses this injury. Moreover, the activities of copper- and zinc-containing superoxide dismutase (CuZn-SOD) and catalase (CAT) are decreased in the livers of diosbulbin B-treated mice, while ferulic acid reverses these decreases. Further results demonstrate that the mRNA expressions of CuZn-SOD and CAT in diosbulbin B-treated mouse liver are significantly decreased, while ferulic acid prevents this decrease. In addition, ferulic acid also augments diosbulbin B-induced tumor growth inhibition compared with diosbulbin B alone. Taken together, the present study shows that ferulic acid prevents diosbulbin B-induced liver injury via ameliorating diosbulbin B-induced liver oxidative stress injury and augments diosbulbin B-induced anti-tumor activity.

Attenuating sevoflurane-induced cellular injury of human peripheral lymphocytes by propofol in a concentration-dependent manner

Sevoflurane, one of the most commonly used inhalation anesthetics, induces apoptosis and oxidative stress in lymphocytes. Propofol, an intravenous anesthetic, exhibits antiapoptotic and antioxidative activities. Therefore, the present study aimed to investigate whether propofol attenuates sevoflurane-induced cellular injury in human peripheral lymphocytes. Lymphocytes harvested from healthy volunteers were assigned to treatments with different concentrations of propofol, or 8% sevoflurane, or their combination. Propofol at concentrations of 5, 10 or 25 μg/mL had little effect, but 50 μg/mL propofol or 8% sevoflurane significantly reduced cell viability and mitochondrial membrane potential (ΔΦm), and increased cell apoptosis, activation of caspase-3 and the production of intracellular reactive oxygen species, compared with untreated cells. Five and ten μg/mL propofol attenuated the impact of sevoflurane on cell viability, apoptosis and ΔΦm, and 5, 10 and 25 μg/mL propofol inhibited the production of intracellular reactive oxygen species stimulated by sevoflurane. However, a combination of 50 μg/mL propofol and 8% sevoflurane led to more severe cellular injury than sevoflurane alone. The results suggest that propofol can attenuate sevoflurane-induced cellular injury of human peripheral lymphocytes in a concentration-dependent manner, providing a rational for the clinical use of sevoflurane combined with appropriate doses of propofol.

Gender-related difference in liver injury induced by Dioscorea bulbifera L. rhizome in mice

The present study was undertaken to investigate the gender-related liver injury induced by Dioscorea bulbifera L. (DB), a traditional medicinal plant, in mice, and further explored its hepatotoxic chemical compound. Serum and liver tissue samples were collected at 0, 4, 8, 12 h, after mice were administrated orally with 640 mg/kg ethyl acetate extracts (EF) isolated from DB. After treatments, serum alanine transaminase (ALT) and aspartate transaminase (AST) activities were both significantly elevated. Liver lipid peroxidation (LPO) level increased, while glutathione amounts, glutathione- S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT) activities all decreased in the time-dependent manner. Further analysis demonstrated that ALT and AST activities in female mice were significantly lower than those in male. Meanwhile, liver glutathione amounts and CAT activity in female mice after giving EF for 12 h were both higher than those in male. Further, comparing the liver injury induced by Diosbulbin B isolated from DB with that induced by EF on the basis of chemical analysis for the amounts of Diosbulbin B in EF of DB, we found that Diosbulbin B could be the main hepatotoxic chemical compound in DB. Taken together, our results show that DB can induce gender-related liver oxidative stress injury in mice, and its main hepatotoxic chemical compound is Diosbulbin B, for the first time.