Comparative Effects of Phosphoenolpyruvate, a Glycolytic Intermediate, as an Organ Preservation Agent with Glucose and N-Acetylcysteine against Organ Damage during Cold Storage of Mouse Liver and Kidney

We evaluated the usefulness of phosphoenolpyruvate (PEP), a glycolytic intermediate with antioxidative and energy supplementation potentials, as an organ preservation agent. Using ex vivo mouse liver and kidney of a static cold storage model, we compared the effects of PEP against organ damage and oxidative stress during cold preservation with those of glucose or N-acetylcysteine (NAC). Lactate dehydrogenase (LDH) leakage, histological changes, and oxidative stress parameters (measured as thiobarbituric acid reactive substance and glutathione content) were determined. PEP (100 mM) significantly prevented an increase in LDH leakage, histological changes, such as tubulonecrosis and vacuolization, and changes in oxidative stress parameters during 72 h of cold preservation in mouse liver. Although glucose (100 mM) partly prevented LDH leakage and histological changes, no effects against oxidative stress were observed. By contrast, NAC inhibited oxidative stress in the liver and did not prevent LDH leakage or histological changes. PEP also significantly prevented kidney damage during cold preservation in a dose-dependent manner, and the protective effects were superior to those of glucose and NAC. We suggest that PEP, a functional carbohydrate with organ protective and antioxidative activities, may be useful as an organ preservation agent in clinical transplantation.

Comparative effects of respiratory stimulants on hypoxic neuronal cell injury in SH-SY5Y cells and in hippocampal slice cultures from rat pups

BACKGROUND

This study was conducted to clarify whether respiratory stimulants used to treat apnea of prematurity (AOP) attenuate or aggravate hypoxia-induced neuronal damage.

METHODS

A human neuroblastoma cell line, SH-SY5Y cells, and hippocampal slice cultures from rat pups were exposed to hypoxia to induce cell injury. The effects of respiratory stimulants on cell injury were evaluated.

RESULTS

Theophylline and doxapram did not have any effects against cell injury induced by hypoxia in SH-SY5Y cells and hippocampal slice cultures of rat pups, while caffeine protected these cells and the slice cultures from hypoxia. The protective effects of caffeine in SH-SY5Y cells disappeared with co-treatment by the adenosine A2A receptor agonist, CGS21680, and were mimicked by the adenosine A2A R antagonist, SCH58261. Meanwhile, co-treatment with phosphatidylinositol 3-kinase/AKT pathway inhibitors did not affect the protective effects of caffeine. Hydroxy radical scavenging activity of caffeine were not observed at the concentrations that produced cytoprotective activity, and radical scavengers did not have any effects on the cell injury induced by hypoxia in SH-SY5Y cells.

CONCLUSIONS

Caffeine significantly attenuated cell injury induced by hypoxia in SH-SY5Y cells and hippocampal slice cultures of rat pups, at least partly through A2A R antagonism. Caffeine can protect neuronal cells from injury induced by hypoxemia, and may be a beneficial treatment for AOP with neuroprotective potential.

Ozagrel hydrochloride, a selective thromboxane A₂ synthase inhibitor, alleviates liver injury induced by acetaminophen overdose in mice

Background

Overdosed acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) causes severe liver injury. We examined the effects of ozagrel, a selective thromboxane A₂ (TXA₂) synthase inhibitor, on liver injury induced by APAP overdose in mice.

Methods

Hepatotoxicity was induced to ICR male mice by an intraperitoneal injection with APAP (330 mg/kg). The effects of ozagrel (200 mg/kg) treatment 30 min after the APAP injection were evaluated with mortality, serum alanine aminotransferase (ALT) levels and hepatic changes, including histopathology, DNA fragmentation, mRNA expression and total glutathione contents. The impact of ozagrel (0.001-1 mg/mL) on cytochrome P450 2E1 (CYP2E1) activity in mouse hepatic microsome was examined. RLC-16 cells, a rat hepatocytes cell line, were exposed to 0.25 mM N-acetyl-p-benzoquinone imine (NAPQI), a hepatotoxic metabolite of APAP. In this model, the cytoprotective effects of ozagrel (1–100 muM) were evaluated by the WST-1 cell viability assay.

Results

Ozagel treatment significantly attenuated higher mortality, elevated serum alanine aminotransferase levels, excessive hepatic centrilobular necrosis, hemorrhaging and DNA fragmentation, as well as increase in plasma 2,3-dinor thromboxane B₂ levels induced by APAP injection. Ozagrel also inhibited the hepatic expression of cell death-related mRNAs induced by APAP, such as jun oncogene, FBJ osteosarcoma oncogene (fos) and C/EBP homologous protein (chop), but did not suppress B-cell lymphoma 2-like protein11 (bim) expression and hepatic total glutathione depletion. These results show ozagrel can inhibit not all hepatic changes but can reduce the hepatic necrosis. Ozagrel had little impact on CYP2E1 activity involving the NAPQI production. In addition, ozagrel significantly attenuated cell injury induced by NAPQI in RLC-16.

Conclusions

We demonstrate that the TXA₂ synthase inhibitor, ozagrel, dramatically alleviates liver injury induced by APAP in mice, and suggest that it is a promising therapeutic candidate for the treatment of APAP-induced liver injury.

Phosphoenolpyruvate, a glycolytic intermediate, as a cytoprotectant and antioxidant in ex-vivo cold-preserved mouse liver: a potential application for organ preservation

OBJECTIVES

The aim of this study was to examine the effect of phosphoenolpyruvate (PEP), a glycolytic intermediate, on organ damage during cold preservation of liver.

METHODS

An ex-vivo mouse liver cold-preservation model and an in-vitro liver injury model induced by hydrogen peroxide in HepG2 cells were leveraged.

KEY FINDINGS

PEP attenuated the elevation of aminotransferases and lactate dehydrogenase leakage during organ preservation, histological changes and changes in oxidative stress parameters (measured as thiobarbituric acid reactive substance and glutathione content) induced by 72 h of cold preservation of the liver. The effects were comparable with the University of Wisconsin solution, a gold standard organ preservation agent. The decrease in ATP content in liver during the cold preservation was attenuated by PEP treatment. PEP prevented the cellular injury and increases in intracellular reactive oxygen species in HepG2 cells. In addition, PEP scavenged hydroxyl radicals, but had no effect on superoxide anion as evaluated by an electron paramagnetic resonance spin-trapping technique.

CONCLUSIONS

PEP significantly attenuated the injury, oxidative stress and ATP depletion in liver during cold preservation. The antioxidative potential of PEP was confirmed by in-vitro examination. We suggest that PEP acts as a glycolytic intermediate and antioxidant, and is particularly useful as an organ preservation agent in clinical transplantation.