Role of 20‐HETE in neuronal signaling and contribution to neonatal hypoxic‐ischemic encephalopathy

Abstract

20‐HETE serves as an intracellular signaling molecule and contributes to infarction in ischemic stroke, but its role in neuronal signaling and in neonatal global cerebral ischemia has not been well studied. Microdialysis probes were inserted in the putamen of anesthetized piglets and perfused with 20‐HETE. Western blot analysis revealed increased serine phosphorylation on Na,K‐ATPase and NMDA NR1 selectively at PKC‐ but not PKA‐sensitive sites. In piglets subjected to hypoxia‐ischemia (H‐I) by systemic hypoxia followed by asphyxia, increased phosphorylation was present in putamen at 3 h of recovery at both PKC‐ and PKA‐sensitive sites on these same proteins. Injection of the 20‐HETE synthesis inhibitor, HET0016 (1 mg/kg), at 5 min of recovery reduced the phosphorylation selectively at the PKC‐sensitive sites on these proteins, improved recovery of Na,K‐ATPase activity, reduced protein carbonyl and nitrotyrosine immunoreactivity, and reduced phosphorylation of Erk1/2 normally seen at 3 h after H‐I. HET0016 did not affect the recovery of cerebral blood flow. Neurobehavioral deficits were ameliorated by HET0016, and over half of the neurons in putamen were protected at 4 days after H‐I. Thus, 20‐HETE can exert direct effects on key proteins involved in neuronal excitotoxicity and contribute to striatal neurodegeneration in neonatal H‐I. (Supported by NIH grants NS060703 and HL59996.)