Neuroprotective effect of hydrogen peroxide on an in vitro model of brain ischaemia

Abstract

Background and purpose: Reactive oxygen species (ROS) have been postulated to play a crucial role in the pathogenesis of ischaemia-reperfusion injury. Among these, hydrogen peroxide (H 2 O 2 ) is known to be a toxic compound responsible for freeradical-dependent neuronal damage. In recent years, however, the 'bad reputation' of H 2 O 2 and other ROS molecules has changed. The aim of this study was to assess the protective role of H 2 O 2 and modification in its endogenous production on the electrophysiological and morphological changes induced by oxygen/glucose deprivation (OGD) on CA1 hippocampal neurons. Experimental approach: Neuroprotective effects of exogenous and endogenous H 2 O 2 were determined using extracellular electrophysiological recordings of field excitatory post synaptic potentials (fEPSPs) and morphological studies in a hippocampal slice preparation. In vitro OGD was delivered by switching to an artificial cerebrospinal fluid solution with no glucose and with oxygen replaced by nitrogen. Key results: Neuroprotection against in vitro OGD was observed in slices treated with H 2 O 2 (3 mM). The rescuing action of H 2 O 2 was mediated by catalase as pre-treatment with the catalase inhibitor 3-amino-1,2,4-triazole blocked this effect. More interestingly, we showed that an increase of the endogenous levels of H 2 O 2 , due to a combination of an inhibitor of the glutathione peroxidase enzyme and addition of Cu,Zn-superoxide dismutase in the tissue bath, prevented the OGD-induced irreversible depression of fEPSPs. Conclusions and implications: Taken together, our results suggest new possible strategies to lessen the damage produced by a transient brain ischaemia by increasing the endogenous tissue level of H 2 O 2 .

Hydrogen Peroxide Stimulates the Epithelial Sodium Channel through a Phosphatidylinositide 3-Kinase-dependent Pathway

“…Therefore, such high concentrations of H 2 O 2 can be used as a tool to manipulate the levels of intracellular H 2 O 2 in A6 cells. This argument is probably also true for neurons because in the hippocampus, the IC 50 for extracellular H 2 O 2 to affect postsynaptic potentials is nearly 6 mM (33). Because, in the present study, H 2 O 2 was applied outside the patch pipette (not to ENaC in the patch), it remains to be determined whether extracellular H 2 O 2 could also directly regulate ENaC by oxidizing cysteine and/or histidine residues in the extracellular loops of ENaC subunits.…”

The Protective Role of Catalase against Cerebral Ischemia in Vitro and in Vivo

“…and subsequently sacrificed by decapitation. Preparation and maintenance of rodent hippocampal slices were performed as previously described (19). Briefly, the brain was rapidly removed from the skull and immersed in ice-cold artificial cerebrospinal fluid (ACSF).…”

“…During an ischemic event not only a rapid removal of ROS, but also an alternative supply of O 2 (from ROS degradation) could be important to reduce tissue damage. Several reports have suggested neuroprotective effects of HP2 against hypoxia and OGD in brain slices of the substantia nigra, hippocampus, striatum and in an in vivo model of cerebral ischemia which is dependent on CAT-mediated production of O 2 (17)(18)(19)(20). To date, the neuroprotective potential of manipulating the levels of CAT has not been explored.…”

Effects of Oxidative Stress on the Electrophysiological Function of Neuronal Membranes

“…H 2 O 2 is able to diffuse across biological membranes, and therefore can diffuse freely from a site of generation (Bienert et al, 2007;Makino et al, 2004) so that it is well-suited as a diffusible messenger. Increasing evidence indicates that H 2 O 2 is a particularly intriguing candidate as an intracellular and intercellular signaling molecule because it is neutral and membrane-permeable (Nistico et al, 2008;Forman et al, 2010). Recent research into mechanisms of ROS-induced modifications in ion transport pathways involves: oxidation of sulfhydryl (SH) groups on the ion transport proteins, lipid peroxidation, and alterations of calcium (Ca 2+ ) homeostasis, a major second messenger system (Kourie, 1998).…”