Protective effect of 20-HETE inhibition in a model of oxygen-glucose deprivation in hippocampal slice cultures

Abstract

Recent studies have indicated that inhibitors of the synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE) may have direct neuroprotective actions since they reduce infarct volume after ischemia reperfusion in the brain without altering blood flow. To explore this possibility, the present study used organotypic hippocampal slice cultures subjected to oxygen-glucose deprivation (OGD) and reoxygenation to examine whether 20-HETE is released by organotypic hippocampal slices after OGD and whether it contributes to neuronal death through the generation of ROS and activation of caspase-3. The production of 20-HETE increased twofold after OGD and reoxygenation. Blockade of the synthesis of 20-HETE with N-hydroxy-N=-(4-butyl-2-methylphenol)formamidine (HET0016) or its actions with a 20-HETE antagonist, 20-hydroxyeicosa-6(Z),15(Z)-dienoic acid, reduced cell death, as measured by the release of lactate dehydrogenase and propidium iodide uptake. Administration of a 20-HETE mimetic, 20-hydroxyeicosa-5(Z),14(Z)-dienoic acid (5,14-20-HEDE), had the opposite effect and increased injury after OGD. The death of neurons after OGD was associated with an increase in the production of ROS and activation of caspase-3. These effects were attenuated by HET0016 and potentiated after the administration of 5,14-20-HEDE. These findings indicate that the production of 20-HETE by hippocampal slices is increased after OGD and that inhibitors of the synthesis or actions of 20-HETE protect neurons from ischemic cell death. The protective effect of 20-HETE inhibitors is associated with a decrease in superoxide production and activation of caspase-3. 20-hydroxyeicosatetraenoic acid; brain; ischemic injury; superoxide; caspase-3 20-HYDROXYEICOSATETRAENOIC ACID (20-HETE) is a potent vasoconstrictor that is produced from -hydroxylation of arachidonic acid (AA) by cytochrome P-450 (CYP) enzymes in cerebral arteries (8,12). It is also produced by brain tissue (39). Plasma levels of 20-HETE increase after transient cerebral ischemia (26), and inhibitors of the synthesis and/or action of 20-HETE markedly reduce infarct size after cerebral ischemia (26,28,31,39). The mechanism of the neuroprotective effects of inhibitors of the synthesis and/or actions of 20-HETE remains unknown. They were initially assumed to improve cerebral perfusion. However, recent studies (28, 31) have demonstrated that inhibitors of the synthesis of 20-HETE have no effect on regional cerebral blood flow during the ischemic period and only attenuate the delayed postischemic fall in cerebral blood flow. Moreover, the previous finding that inhibitors of the synthesis of 20-HETE can reduce infarct size in the brain even when administered 4 h after reperfusion (26) suggests that these drugs may enhance the survival of neurons after ischemic injury independent of their effects on cerebral blood flow.In this regard, there is increasing evidence that 20-HETE stimulates oxidative stress through several mechanisms, including the activation of NADPH oxidase, phosphorylation and uncoupling ...

20-Hydroxyeicosatetraenoic Acid Inhibition by HET0016 Offers Neuroprotection, Decreases Edema, and Increases Cortical Cerebral Blood Flow in a Pediatric Asphyxial Cardiac Arrest Model in Rats

“…26,31 In other studies, 20-HETE inhibition reduced lesion volume and neurodegeneration independent of CBF, suggesting a direct neuroprotective effect of 20-HETE inhibition. 17,18,32 In a global cerebral ischemia model in immature piglets similar in some ways to our model, Yang et al 17 showed direct neuroprotection after CA in piglets treated with HET0016. In that report, focal cortical CBF measured by laser Doppler was not affected by treatment with HET0016 at 5 minutes after resuscitation.…”

Increase of 20-HETE Synthase after Brain Ischemia in Rats Revealed by PET Study with 11C-Labeled 20-HETE Synthase-Specific Inhibitor

“…ND, not detected. Recent studies reported that CYP4A immunoreactivity was detected in neurons in hippocampus and putamen (Renic et al, 2012;Yang et al, 2012). In this study, CYP4A immunoreactivity was also detected in neurons in contralateral cortex and striatum.…”

Targeting vascular inflammation in ischemic stroke: Recent developments on novel immunomodulatory approaches

“…Inhibition of 20-HETE not only reduces infarct size, but also improves neurological outcomes in MCAO models (Dunn et al, 2008; Renic et al, 2009). Blockade of 20-HETE synthesis alleviated neuronal cell death in brain slices subjected to oxygen and glucose deprivation in association with decreased superoxide production and caspase-3 activation (Renic et al, 2012). The neuroprotective effect of 20-HETE inhibition could be explained by amelioration of inflammation, as well as oxidative stress, by diminishing recruitment of leukocytes, decreasing production of IL-1, IL-6, chemokine (C-C motif) ligand 2 (CCL2) (aka monocyte chemoattractant protein-1 (MCP-1)), interferon gamma (IFN-γ), TNF-α, and reducing expression of ICAM-1 and VCAM-1 on B-lymphocytes and endothelium (Shekhar et al, 2017a; Toth et al, 2013).…”