Attenuation of neonatal ischemic brain damage using a 20-HETE synthesis inhibitor

J. Neurochem. (2012) 121, 168–179. 20‐Hydroxyeicosatetraenoic acid (20‐HETE) is a cytochrome P450 metabolite of arachidonic acid that that contributes to infarct size following focal cerebral ischemia. However, little is known about the role of 20‐HETE in global cerebral ischemia or neonatal hypoxia‐ischemia (H‐I). The present study examined the effects of blockade of the synthesis of 20‐HETE with N‐hydroxy‐N′‐(4‐n‐butyl‐2‐methylphenyl) formamidine (HET0016) in neonatal piglets after H‐I to determine if it protects highly vulnerable striatal neurons. Administration of HET0016 after H‐I improved early neurological recovery and protected neurons in putamen after 4 days of recovery. HET0016 had no significant effect on cerebral blood flow. cytochrome P450 4A immunoreactivity was detected in putamen neurons, and direct infusion of 20‐HETE in the putamen increased phosphorylation of Na+,K+‐ATPase and NMDA receptor NR1 subunit selectively at protein kinase C‐sensitive sites but not at protein kinase A‐sensitive sites. HET0016 selectively inhibited the H‐I induced phosphorylation at these same sites at 3 h of recovery and improved Na+,K+‐ATPase activity. At 3 h, HET0016 also suppressed H‐I induced extracellular signal‐regulated kinase 1/2 activation and protein markers of nitrosative and oxidative stress. Thus, 20‐HETE can exert direct effects on key proteins involved in neuronal excitotoxicity in vivo and contributes to neurodegeneration after global cerebral ischemia in immature brain. Little is known about the role of 20‐HETE in neonatal hypoxia‐ischemia. Here, blockade of 20‐HETE synthesis with HET0016 in newborn piglets after H‐I had no significant effect on cerebral blood flow. However, it inhibited the PKC‐dependent NMDA receptor and Na, K‐ATPase phosphorylation, and improved Na, K‐ATPase activity. Thus, 20‐HETE can exert direct effects on proteins involved in neuronal excitotoxicity in immature brain.