Microsomal epoxide hydrolase (mEH), first identified as detoxifying enzyme, can hydrolyze epoxyeicosatrienoic acids (EETs) to less active diols (DHETs). EETs are potent vasodilatory and pro-angiogenic lipids, also implicated in neurovascular coupling. In mouse brain, mEH is strongly expressed in vascular and perivascular cells in contrast to the related soluble epoxide hydrolase (sEH), predominantly found in astrocytes. While sEH inhibition in stroke has demonstrated neuroprotective effects and increases cerebral blood flow (CBF), data regarding the role of mEH in brain are scarce. Here, we explored the function of mEH in cerebral vasculature by comparing mEH-KO, sEH-KO and WT mice. Basal cerebral volume (CBV0) was significantly higher in various mEH-KO brain areas compared to WT and sEH-KO. In line, quantification of cerebral vasculature in cortex and thalamus revealed a higher capillary density in mEH-KO, but not in sEH-KO brain. Whisker-stimulated CBF changes were by factor two higher in both mEH-KO and sEH-KO. In acutely isolated cerebral endothelial cells the loss of mEH, but not of sEH, augmented total EET levels and decreased the DHET:EET ratio. Collectively, these data suggest an important function of mEH in the regulation of cerebral vasculature and activity-modulated CBF, presumably by controlling local levels of endothelial-derived EETs.
OeschF.Significance of various enzymes in the control of reactive metabolites. Arch Toxicol1987;
60: 174–178.
2.
MarowskyABurgenerJFalckJR, et al.
Distribution of soluble and microsomal epoxide hydrolase in the mouse brain and its contribution to cerebral epoxyeicosatrienoic acid metabolism. Neuroscience2009;
163: 646–661.
3.
MarowskyAMeyerIErismann-EbnerK, et al.
Beyond detoxification: a role for mouse mEH in the hepatic metabolism of endogenous lipids. Arch Toxicol2017;
91: 3571–3585.
4.
EdinMLZeldinDC.Regulation of cardiovascular biology by microsomal epoxide hydrolase. Toxicol Res2021;
37: 285–292.
5.
MorisseauCKodaniSDKamitaSG, et al.
Relative importance of soluble and microsomal epoxide hydrolases for the hydrolysis of epoxy-fatty acids in human tissues. Int J Mol Sci2021;
22: 4993.
6.
AlkayedNJNarayananJGebremedhinD, et al.
Molecular characterization of an arachidonic acid epoxygenase in rat brain astrocytes. Stroke1996;
27: 971–979.
7.
CarverKALourimDTrybaAK, et al.
Rhythmic expression of cytochrome P450 epoxygenases CYP4 × 1 and CYP2c11 in the rat brain and vasculature. Am J Physiol Cell Physiol2014;
307: C989–998.
8.
MorisseauCInceogluBSchmelzerK, et al.
Naturally occurring monoepoxides of eicosapentaenoic acid and docosahexaenoic acid are bioactive antihyperalgesic lipids. J Lipid Res2010;
51: 3481–3490.
9.
DeckerMAdamskaMCroninA, et al.
EH3 (ABHD9): the first member of a new epoxide hydrolase family with high activity for fatty acid epoxides. J Lipid Res2012;
53: 2038–2045.
10.
VanlandewijckMHeLMäeMA, et al.
A molecular atlas of cell types and zonation in the brain vasculature. Nature2018;
554: 475–480.
11.
PengXCarhuapomaJRBhardwajA, et al.
Suppression of cortical functional hyperemia to vibrissal stimulation in the rat by epoxygenase inhibitors. Am J Physiol Heart Circ Physiol2002;
283: H2029–2037.
12.
AttwellDBuchanAMCharpakS, et al.
Glial and neuronal control of brain blood flow. Nature2010;
468: 232–243.
13.
NippertARBieseckerKRNewmanEA.Mechanisms mediating functional hyperemia in the brain. Neuroscientist2018;
24: 73–83.
14.
AlkayedNJBirksEKNarayananJ, et al.
Role of P-450 arachidonic acid epoxygenase in the response of cerebral blood flow to glutamate in rats. Stroke1997;
28: 1066–1072.
15.
DavisCMLiuXAlkayedNJ.Cytochrome P450 eicosanoids in cerebrovascular function and disease. Pharmacol Ther2017;
179: 31–46.
16.
LiPLCampbellWB.Epoxyeicosatrienoic acids activate K+ channels in coronary smooth muscle through a guanine nucleotide binding protein. Circ Res1997;
80: 877–884.
17.
MacVicarBANewmanEA.Astrocyte regulation of blood flow in the brain. Cold Spring Harb Perspect Biol2015;
7.
18.
ZhangWKoernerIPNoppensR, et al.
Soluble epoxide hydrolase: a novel therapeutic target in stroke. J Cereb Blood Flow Metab2007;
27: 1931–1940.
19.
ShaikJSAhmadMLiW, et al.
Soluble epoxide hydrolase inhibitor trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid is neuroprotective in rat model of ischemic stroke. Am J Physiol Heart Circ Physiol2013;
305: H1605–1613.
20.
ZhangWOtsukaTSugoN, et al.
Soluble epoxide hydrolase gene deletion is protective against experimental cerebral ischemia. Stroke2008;
39: 2073–2078.
21.
ZuloagaKLZhangWRoeseNE, et al.
Soluble epoxide hydrolase gene deletion improves blood flow and reduces infarct size after cerebral ischemia in reproductively senescent female mice. Front Pharmacol2014;
5: 290.
22.
MarowskyAHaenelKBockampE, et al.
Genetic enhancement of microsomal epoxide hydrolase improves metabolic detoxification but impairs cerebral blood flow regulation. Arch Toxicol2016;
90: 3017–3027.
23.
MedhoraMNarayananJHarderD.Dual regulation of the cerebral microvasculature by epoxyeicosatrienoic acids. Trends Cardiovasc Med2001;
11: 38–42.
24.
MedhoraMDanielsJMundeyK, et al.
Epoxygenase-driven angiogenesis in human lung microvascular endothelial cells. Am J Physiol Heart Circ Physiol2003;
284: H215–224.
25.
SanderALJakobHSommerK, et al.
Cytochrome P450-derived epoxyeicosatrienoic acids accelerate wound epithelialization and neovascularization in the hairless mouse ear wound model. Langenbecks Arch Surg2011;
396: 1245–1253.
26.
ZhangCHarderDR.Cerebral capillary endothelial cell mitogenesis and morphogenesis induced by astrocytic epoxyeicosatrienoic acid. Stroke2002;
33: 2957–2964.
27.
PozziAMacias-PerezIAbairT, et al.
Characterization of 5,6- and 8,9-epoxyeicosatrienoic acids (5,6- and 8,9-EET) as potent in vivo angiogenic lipids. J Biol Chem2005;
280: 27138–27146.
28.
SanderALSommerKNeumayerT, et al.
Soluble epoxide hydrolase disruption as therapeutic target for wound healing. J Surg Res2013;
182: 362–367.
29.
SommerKJakobHBadjlanF, et al.
11,12 and 14,15 epoxyeicosatrienoic acid rescue deteriorated wound healing in ischemia. PLoS One2019;
14: e0209158.
30.
SommerKJakobHReicheC, et al.
11,12 Epoxyeicosatrienoic acid rescues deteriorated wound healing in diabetes. Int J Mol Sci2021;
22: 11664.
31.
MiyataMKudoGLeeYH, et al.
Targeted disruption of the microsomal epoxide hydrolase gene. Microsomal epoxide hydrolase is required for the carcinogenic activity of 7,12-dimethylbenz[a]anthracene. J Biol Chem1999;
274: 23963–23968.
32.
SinalCJMiyataMTohkinM, et al.
Targeted disruption of soluble epoxide hydrolase reveals a role in blood pressure regulation. J Biol Chem2000;
275: 40504–40510.
33.
Percie du SertNHurstVAhluwaliaA, et al.
The ARRIVE guidelines 2.0: updated guidelines for reporting animal research. J Physiol2020;
598: 3793–3801.
34.
MuegglerTBaumannDRauschM, et al.
Bicuculline-induced brain activation in mice detected by functional magnetic resonance imaging. Magn Reson Med2001;
46: 292–298.
35.
ReblingJBen-Yehuda GreenwaldMWietechaM, et al.
Long-term imaging of wound angiogenesis with large scale optoacoustic microscopy. Adv Sci (Weinh)2021;
8: 2004226.
36.
ZakharovPVölkerACWyssMT, et al.
Dynamic laser speckle imaging of cerebral blood flow. Opt Express2009;
17: 13904–13917.
37.
GoldimMPSDella GiustinaAPetronilhoF.Using Evans Blue dye to determine blood-brain barrier integrity in rodents. Curr Protoc Immunol2019;
126: e83.
38.
TsaiPSKaufholdJPBlinderP, et al.
Correlations of neuronal and microvascular densities in murine cortex revealed by direct counting and colocalization of nuclei and vessels. J Neurosci2009;
29: 14553–14570.
39.
ZellerKVogelJKuschinskyW.Postnatal distribution of Glut1 glucose transporter and relative capillary density in blood-brain barrier structures and circumventricular organs during development. Brain Res Dev Brain Res1996;
91: 200–208.
40.
YueFChengYBreschiA, et al.
A comparative encyclopedia of DNA elements in the mouse genome. Nature2014;
515: 355–364.
41.
HallCNReynellCGessleinB, et al.
Capillary pericytes regulate cerebral blood flow in health and disease. Nature2014;
508: 55–60.
42.
KatzSGattegnoRPekoL, et al.
Diameter-dependent assessment of microvascular leakage following ultrasound-mediated blood-brain barrier opening. iScience2023;
26: 106965.
43.
VanellaLCanestraroMLeeCR, et al.
Soluble epoxide hydrolase null mice exhibit female and male differences in regulation of vascular homeostasis. Prostaglandins Other Lipid Mediat2015;
120: 139–147.
44.
WangHLinLJiangJ, et al.
Up-regulation of endothelial nitric-oxide synthase by endothelium-derived hyperpolarizing factor involves mitogen-activated protein kinase and protein kinase C signaling pathways. J Pharmacol Exp Ther2003;
307: 753–764.
45.
PanigrahyDEdinMLLeeCR, et al.
Epoxyeicosanoids stimulate multiorgan metastasis and tumor dormancy escape in mice. J Clin Invest2012;
122: 178–191.
46.
RandAABarnychBMorisseauC, et al.
Cyclooxygenase-derived proangiogenic metabolites of epoxyeicosatrienoic acids. Proc Natl Acad Sci U S A2017;
114: 4370–4375.
47.
RandAARajamaniAKodaniSD, et al.
Epoxyeicosatrienoic acid (EET)-stimulated angiogenesis is mediated by epoxy hydroxyeicosatrienoic acids (EHETs) formed from COX-2. J Lipid Res2019;
60: 1996–2005.
48.
RibattiDNicoBCrivellatoE.The role of pericytes in angiogenesis. Int J Dev Biol2011;
55: 261–268.
49.
ArmulikAGenovéGBetsholtzC.Pericytes: developmental, physiological, and pathological perspectives, problems, and promises. Developmental Cell2011;
21: 193–215.
50.
SpectorAANorrisAW.Action of epoxyeicosatrienoic acids on cellular function. Am J Physiol Cell Physiol2007;
292: C996–1012.
51.
ZhangWDavisCMZeppenfeldDM, et al.
Role of endothelium-pericyte signaling in capillary blood flow response to neuronal activity. J Cereb Blood Flow Metab2021;
41: 1873–1885.
52.
ZhangYHongGLeeKS, et al.
Inhibition of soluble epoxide hydrolase augments astrocyte release of vascular endothelial growth factor and neuronal recovery after oxygen-glucose deprivation. J Neurochem2017;
140: 814–825.
53.
HerculeHCSchunckWHGrossV, et al.
Interaction between P450 eicosanoids and nitric oxide in the control of arterial tone in mice. Arterioscler Thromb Vasc Biol2009;
29: 54–60.
54.
WangSQiYYuL, et al.
Endogenous nitric oxide regulates blood vessel growth factors, capillaries in the cortex, and memory retention in Sprague-Dawley rats. Am J Transl Res2016;
8: 5271–5285.
55.
WangYWeiXXiaoX, et al.
Arachidonic acid epoxygenase metabolites stimulate endothelial cell growth and angiogenesis via mitogen-activated protein kinase and phosphatidylinositol 3-kinase/Akt signaling pathways. J Pharmacol Exp Ther2005;
314: 522–532.
56.
DingYFrömelTPoppR, et al.
The biological actions of 11,12-epoxyeicosatrienoic acid in endothelial cells are specific to the R/S-enantiomer and require the G(s) protein. J Pharmacol Exp Ther2014;
350: 14–21.
57.
ParkSKHerrnreiterAPfisterSL, et al.
GPR40 is a low-affinity epoxyeicosatrienoic acid receptor in vascular cells. J Biol Chem2018;
293: 10675–10691.
58.
LiuXQianZYXieF, et al.
Functional screening for G protein-coupled receptor targets of 14,15-epoxyeicosatrienoic acid. Prostaglandins Other Lipid Mediat2017;
132: 31–40.
59.
SteinmanJKoletarMMStefanovicB, et al.
3D morphological analysis of the mouse cerebral vasculature: Comparison of in vivo and ex vivo methods. PLoS One2017;
12: e0186676.
60.
Cruz HernándezJCBrackoOKersbergenCJ, et al.
Neutrophil adhesion in brain capillaries reduces cortical blood flow and impairs memory function in Alzheimer's disease mouse models. Nat Neurosci2019;
22: 413–420.
61.
TataDAAndersonBJ.A new method for the investigation of capillary structure. J Neurosci Methods2002;
113: 199–206.
62.
AlturaBTAlturaBM.Effects of barbiturates, phencyclidine, ketamine and analogs on cerebral circulation and cerebrovascular muscle. Microcirc Endothelium Lymphatics1984;
1: 169–184.
63.
ZhangWIliffJJCampbellCJ, et al.
Role of soluble epoxide hydrolase in the sex-specific vascular response to cerebral ischemia. J Cereb Blood Flow Metab2009;
29: 1475–1481. 20090527.
64.
MorisseauCNewmanJWWheelockCE, et al.
Development of metabolically stable inhibitors of Mammalian microsomal epoxide hydrolase. Chem Res Toxicol2008;
21: 951–957.
65.
BarnychBSinghNNegrelS, et al.
Development of potent inhibitors of the human microsomal epoxide hydrolase. Eur J Med Chem2020;
193: 112206.
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
