Soluble epoxide hydrolase gene deletion is protective against experimental cerebral ischemia.
OBJECTIVE
Cytochrome P450 epoxygenase metabolizes arachidonic acid to epoxyeicosatrienoic acids (EETs). EETs are produced in the brain and perform important biological functions, including vasodilation and neuroprotection. However, EETs are rapidly metabolized via soluble epoxide hydrolase (sEH) to dihydroxyeicosatrienoic acids (DHETs). We tested the hypothesis that sEH gene deletion is protective against focal cerebral ischemia through enhanced collateral blood flow.


METHODS
sEH knockout (sEHKO) mice with and without EETs antagonist 14, 15 epoxyeicosa-5(Z)-enoic acid (EEZE) were subjected to 2-hour middle cerebral artery occlusion (MCAO), and infarct size was measured at 24 hours of reperfusion and compared to wild-type (WT) mice. Local CBF rates were measured at the end of MCAO using iodoantipyrine (IAP) autoradiography, sEH protein was analyzed by Western blot and immunohistochemistry, and hydrolase activity and levels of EETs/DHETs were measured in brain and plasma using LC-MS/MS and ELISA, respectively.


RESULTS
sEH immunoreactivity was detected in WT, but not sEHKO mouse brain, and was localized to vascular and nonvascular cells. 14,15-DHET was abundantly present in WT, but virtually absent in sEHKO mouse plasma. However, hydrolase activity and free 14,15-EET in brain tissue were not different between WT and sEHKO mice. Infarct size was significantly smaller, whereas regional cerebral blood flow rates were significantly higher in sEHKO compared to WT mice. Infarct size reduction was recapitulated by 14,15-EET infusion. However, 14,15-EEZE did not alter infarct size in sEHKO mice.


CONCLUSIONS
sEH gene deletion is protective against ischemic stroke by a vascular mechanism linked to reduced hydration of circulating EETs.
Zhang
Wenri
W
Oregon Health & Science University, Department of Anesthesiology & Peri-Operative Medicine, 3181 SW Sam Jackson Park Road, Portland, OR 97239-3098, USA.
Otsuka
Takashi
T
Sugo
Nobuo
N
Ardeshiri
Ardi
A
Alhadid
Yazan K
YK
Iliff
Jeffrey J
JJ
DeBarber
Andrea E
AE
Koop
Dennis R
DR
Alkayed
Nabil J
NJ
D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism*; D001345:Autoradiography; D001921:Brain / Q000473:pathology; D002545:Brain Ischemia / Q000235:genetics* / Q000473:pathology*; D015777:Eicosanoids / Q000378:metabolism; D004851:Epoxide Hydrolases / Q000235:genetics* / Q000502:physiology*; D017353:Gene Deletion; D006720:Homozygote; D020244:Infarction, Middle Cerebral Artery / Q000235:genetics* / Q000517:prevention & control*; D013058:Mass Spectrometry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout
D001095:Arachidonic Acids; D015777:Eicosanoids; C067407:14,15-episulfide eicosatrienoic acid; D004851:Epoxide Hydrolases; D015126:8,11,14-Eicosatrienoic Acid