The protective effect of astrocyte-derived 14,15-epoxyeicosatrienoic acid on hydrogen peroxide-induced cell injury in astrocyte-dopaminergic neuronal cell line co-culture

Abstract

Astrocytes perform several functions that are essential for normal neuronal activity. They play a critical role in neuronal survival during ischemia and other degenerative injuries and also modulate neuronal recovery by influencing neurite outgrowth. In this study, we investigated the neuroprotective effects of astrocyte-derived 14,15-epoxyeicosatrienoic acid (14,15-EET), metabolite of arachidonic acid by Cytochrome P450 epoxygenases (CYP), against oxidative stress induced by hydrogen peroxide (H2O2). We found that dopaminergic neuronal cells (N27 cell line) stimulated with two different doses of H2O2 (0.1 and 1 mM) for 1h showed decreased cell viability compared to the control group, while astrocytes co-cultured with dopaminergic neuronal cell lines prevented cell during after stimulation with the same doses of H2O2 for 1h. Dopaminergic neuronal cells (N27 cell line) pretreated with different doses of 14, 15-EET (0.1–30 μM, 30 min) before H2O2 stimulation also showed increased cell viability. Furthermore, pre-treatment of the co-cultured cells with 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA), an inhibitor of the EET metabolizing enzyme, soluble epoxide hydrolase (sEH), before H2O2 stimulation (1 mM, for 1h) increased cell viability. It also increased the endogenous level of 14,15-EET in the media compared to control group. However, pretreatment with the CYP epoxygenase inhibitor miconazole (1–20 μM, 1h) before H2O2 (1 mM, 1h) stimulation showed decreased cell viability. Our data suggest that 14,15-EET which is released from astrocytes, enhances cell viability against oxidant induced injury. Further understanding of the mechanism of 14,15-EET-mediated protection in dopaminergic neurons is imperative, as it could lead to novel therapeutic approaches for treating CNS neuropathologies, such as Parkinson’s disease.

Post-exposure administration of diazepam combined with soluble epoxide hydrolase inhibition stops seizures and modulates neuroinflammation in a murine model of acute TETS intoxication

“…The reason for the region-dependent effect is not known, nor is it known why sEHI exerts differential effects on astrocytes versus microglial cells. The sEH enzyme is localized to astrocytes (Marowsky et al , 2009; Rawal et al , 2009; Sura et al , 2008) where it is thought to regulate levels of epoxy fatty acids in the brain (Marowsky et al, 2009; Terashvili et al , 2012), but there is very little information regarding the expression or function of sEH in microglial cells. Similarly, there is little known about the effect of sEH inhibition on the activational status of either astrocytes or microglial cells with the exception of a recent report that pharmacologic inhibition of sEH alters the transcriptional profile of activated microglia to selectively induce anti-inflammatory and neuroprotective cytokine expression (Wang et al, 2013).…”

Cytoprotective propensity of Bacopa monniera against hydrogen peroxide induced oxidative damage in neuronal and lung epithelial cells

“…The possible mechanism of cytoprotection in neuronal and lung epithelial cells by its potent antioxidant propensity was evaluated by estimating the biomarkers known to be induced by oxidative stress. H 2 O 2 is a well known potent inducer of ROS capable of inducing cell injury both in vitro and in vivo (Kim et al 2012;Terashvili et al 2012). Studies have shown that H 2 O 2 is known to induce oxidative damage, leading to lipid peroxidation, ROS generation, GSH depletion and reduction in mitochondrial membrane potential, antioxidant enzymes (SOD, catalase and GPx) activity preceding cell death (Chan et al 2009;Brenner et al 2010;Gulden et al 2010).…”

Cytochrome P450 epoxygenase pathway of polyunsaturated fatty acid metabolism

“…14,15-EET stimulates axon growth in primary cortical and sensory neuron cultures [154], and EETs mediate cerebral vasodilation produced by stimulation of astrocyte metabotropic glutamate receptors, possibly by activating K + channels or TRPV4 channels [114,155,156]. When injected into the rat brain, 14,15-EET produced an anti-nociceptive effect through activation of β-endorphin and met-enkephalin [157], and it reduced the injurious effect of H 2 O 2 in the dopaminergic N27 neuronal cell line [158]. The administration of sEH inhibitors delayed the onset of seizures mediated by GABA, indicating that EET stabilization can suppress pathologic neurotransmission in the brain [159].…”