New pathways driving the experimental hepatoprotective action of tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) against acute hepatotoxicity

Alteration of endoplasmic reticulum stress, inflammation and anti-oxidative status in cyclophosphamide-damaged liver of Nile tilapia (Oreochromis niloticus)

Cyclophosphamide (CTX) is a common immunosuppressant, and it can also results in liver injury in human and animals. In this study, the CTX-induced liver injury mechanism in tilapia (Oreochromis niloticus) was investigated by studying alteration of endoplasmic reticulum stress (ERS), inflammation and anti-oxidative status. Tilapia was intraperitoneally injected CTX at the doses of 10, 25, 50, 75 and 100 mg·kg^-1, and the blood and liver tissues were collected. The results showed that CTX administration had a significant cytotoxicity on hepatocytes, and increased the liver index. The extensive vacuolar degeneration, unclear cell outline and other histological lesions were also observed. CTX administration markedly decreased the antioxidant ability and enhanced lipid peroxidation in liver. Furthermore, qPCR data showed that CTX administration at 50-100 mg·kg^-1 up-regulated gene expressions of cyp1a, cyp2k1 and cyp3a, and inflammatory response-related genes including rel, relb, nfκb1, il-6, il-8, il-10 and tnf-α. CTX significantly promoted the mRNA levels of ERS-related genes (eif2α, crt, parp1, grp78, ire1, xbp1s and chop) in a dose dependent manner. Additionally, CTX injection at 75-100 mg·kg^-1 could down-regulate gene expressions of anti-oxidative status including nrf2, ucp2, ho-1, gpx3, gstα and cat. Overall results suggested CTX injection induced liver damage which was related to the cytotoxic effect on hepatocytes, decrease of antioxidant capacity, inflammatory response and ERS.

Protective Effect of Polydeoxyribonucleotide Against CCl4-Induced Acute Liver Injury in Mice

Purpose

Polydeoxyribonucleotide (PDRN) is a substance known to suppress inflammation and accelerate wound healing. In this experiment, the effect of PDRN treatment on carbon tetrachloride (CCl₄)-evoked acute liver injury (ALI) was investigated using mice.

Methods

We analyzed the levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and conducted hematoxylin and eosin staining in accompany with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining. Western blot analysis was also conducted to assess the expressions of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, adenosine A_2A receptor, Bcl-2-associated X protein (Bax), and B-cell lymphoma 2 (Bcl-2). The mice were received intraperitoneal injection of 10-mL/kg CCl₄, 4 times, once every 2 days. The mice in the PDRN treatment groups received intraperitoneal injection of 200-μL distilled water comprising each concentration of PDRN for 7 days starting 1 day after first CCl₄ injection.

Results

ALT and AST concentrations in the serum were reduced and TNF-α, IL-1β, and IL-6 expressions were decreased by PDRN injection in CCl₄-evoked ALI mice. PDRN injection suppressed Bax versus Bcl-2 ratio and reduced the percentage of TUNE-positive cells in CCl₄-evoked ALI mice. PDRN injection overexpressed adenosine A_2A receptor in CCl₄-evoked ALI mice.

Conclusions

The therapeutic efficacy of PDRN also can be expected for CCl₄-evoked acute urogenital injury in addition to ALI. The current research suggests that PDRN may be used for the therapeutic agent of CCl₄-evoked ALI.

Polydeoxyribonucleotide Exerts Protective Effect Against CCl4-Induced Acute Liver Injury Through Inactivation of NF-κB/MAPK Signaling Pathway in Mice

Acute liver injury (ALI) causes life-threatening clinical problem, and its underlying etiology includes inflammation and apoptosis. An adenosine A_2A receptor agonist, polydeoxyribonucleotide (PDRN), exhibits anti-inflammatory and anti-apoptotic effects by inhibiting the secretion of pro-inflammatory cytokines. In the current study, the protective effect of PDRN against carbon tetrachloride (CCl₄)-induced ALI was investigated using mice. For the induction of ALI, mice received intraperitoneal injection of CCl₄ twice over seven days. Mice from the PDRN-treated groups received an intraperitoneal injection of 200 μL saline containing PDRN (8 mg/kg), once a day for seven days, starting on day 1 after the first CCl₄ injection. In order to confirm that the action of PDRN occurs through the adenosine A_2A receptor, 8 mg/kg 3,7-dimethyl-1-propargylxanthine (DMPX), an adenosine A_2A receptor antagonist, was treated with PDRN. Administration of CCl₄ impaired liver tissue and increased the liver index and histopathologic score. The expression of pro-inflammatory cytokines was increased, and apoptosis was induced by the administration of CCl₄. Administration of CCl₄ activated nuclear factor-kappa B (NF-κB) and facilitated phosphorylation of signaling factors in mitogen-activated protein kinase (MAPK). In contrast, PDRN treatment suppressed the secretion of pro-inflammatory cytokines and inhibited apoptosis. PDRN treatment inactivated NF-κB and suppressed phosphorylation of signaling factors in MAPK. As a result, liver index and histopathologic score were reduced by PDRN treatment. When PDRN was treated with DMPX, the anti-inflammatory and anti-apoptotic effect of PDRN disappeared. Therefore, PDRN can be used as an effective therapeutic agent for acute liver damage.

Atriplex halimus aqueous extract abrogates carbon tetrachloride-induced hepatotoxicity by modulating biochemical and histological changes in rats

The objective of this study was to evaluate the potential protective effect of Atriplex halimus aqueous leaves extract (AHAE) against acute carbon tetrachloride (CCl₄)-induced oxidative stress in rats. Rats were randomly divided into four groups: group (C) served as a control treated with 1 ml/(kg bw) of olive oil, and group (CCl₄) was treated with 1 ml CCl₄/(kg bw) dissolved in olive oil administered by intraperitoneal way. Rats of group (CCl₄+AHAE) have received CCl₄ and treated with 200 mg AHAE/(kg bw). Animals of group (AHAE) were treated with 200 mg/(kg bw) of AHAE. A significant increase in malondialdehyde levels in liver associated with a decrease in antioxidant enzyme activities and reduced glutathione content was observed in CCl₄ group compared to controls. The administration of AHAE to CCl₄+AHAE group improved all parameters studied. We conclude that CCl₄ induces oxidative stress and modifies biochemical parameters and histological aspects of liver. Administration of AHAE alleviates the toxicity induced by this organic compound.

Antioxidant nitroxides protect hepatic cells from oxidative stress-induced cell death

Oxidative stress causes cell death and induces many kinds of disease, including liver disease. Nitroxides are known to react catalytically with free radicals. In this study, the cell protective activities of nitroxides were compared with those of other antioxidants. Nitroxides showed much greater inhibition of hydrogen peroxide-induced cell death than other antioxidants in a hepatic cell line and in primary hepatocytes. The intracellular oxidative stress level at 24 h after hydrogen peroxide stimulation was significantly decreased by nitroxides, but not by other antioxidants. To clarify the mechanism of cell protection by nitroxides, we investigated whether nitroxides inhibited DNA damage and mitogen-activated protein kinase pathway activation. We found that nitroxides reduced caspase-3 activation and may have ultimately inhibited cell death. In conclusion, nitroxides are very useful for attenuating cell damage due to oxidative stress. Nitroxides are thus a potential therapeutic agent for oxidative stress-related diseases.