Soluble Epoxide Inhibition Is Protective Against Cerebral Ischemia via Vascular and Neural Protection

Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
American Journal Of Pathology (Impact Factor: 4.59). 06/2009; 174(6):2086-95. DOI: 10.2353/ajpath.2009.080544
Source: PubMed


Inhibition of soluble epoxide hydrolase (SEH), the enzyme responsible for degradation of vasoactive epoxides, protects against cerebral ischemia in rats. However, the molecular and biological mechanisms that confer protection in normotension and hypertension remain unclear. Here we show that 6 weeks of SEH inhibition via 2 mg/day of 12-(3-adamantan-1-yl-ureido) dodecanoic acid (AUDA) in spontaneously hypertensive stroke-prone (SHRSP) rats protects against cerebral ischemia induced by middle cerebral artery occlusion, reducing percent hemispheric infarct and neurodeficit score without decreasing blood pressure. This level of cerebral protection was similar to that of the angiotensin-converting enzyme inhibitor, enalapril, which significantly lowered blood pressure. SEH inhibition is also protective in normotensive Wistar-Kyoto (WKY) rats, reducing both hemispheric infarct and neurodeficit score. In SHRSP rats, SEH inhibition reduced wall-to-lumen ratio and collagen deposition and increased cerebral microvessel density, although AUDA did not alter middle cerebral artery structure or microvessel density in WKY rats. An apoptosis mRNA expression microarray of brain tissues from AUDA-treated rats revealed that AUDA modulates gene expression of mediators involved in the regulation of apoptosis in neural tissues of both WKY and SHRSP rats. Hence, we conclude that chronic SEH inhibition protects against cerebral ischemia via vascular protection in SHRSP rats and neural protection in both the SHRSP and WKY rats, indicating that SEH inhibition has broad pharmacological potential for treating ischemic stroke.

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Available from: John D Imig, Dec 21, 2013
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    • "In the current study, sEH inhibitor was administered before stroke, which has limited value as a stroke therapy, but is ideal for determining the role of sEH in the exacerbation of stroke injury in brains of type 2 diabetic mice, which was the goal of the current study. Based on previous studies in non-diabetic mice, it is possible that sEH inhibitors could also attenuate neurological deficits following stroke [33], and we intend to address this possibility in future studies. Nevertheless, we show that sEH inhibition improves both glycemic status and cerebral perfusion in the ischemic territory in type 2 diabetic mice when administered as a pre-treatment. "
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    ABSTRACT: Inhibition of soluble epoxide hydrolase (sEH) is a potential target of therapy for ischemic injury. sEH metabolizes neuroprotective epoxyeicosatrienoic acids (EETs). We recently demonstrated that sEH inhibition reduces infarct size after middle cerebral artery occlusion (MCAO) in type 1 diabetic mice. We hypothesized that inhibition of sEH would protect against ischemic injury in type 2 diabetic mice. Type 2 diabetes was produced by combined high-fat diet, nicotinamide and streptozotocin in male mice. Diabetic and control mice were treated with vehicle or the sEH inhibitor t-AUCB then subjected to 60-min MCAO. Compared to chow-fed mice, high fat diet-fed mice exhibited an upregulation of sEH mRNA and protein in brain, but no differences in brain EETs levels were observed between groups. Type 2 diabetic mice had increased blood glucose levels at baseline and throughout ischemia, decreased laser-Doppler perfusion of the MCA territory after reperfusion, and sustained larger cortical infarcts compared to control mice. t-AUCB decreased fasting glucose levels at baseline and throughout ischemia, improved cortical perfusion after MCAO and significantly reduced infarct size in diabetic mice. We conclude that sEH inhibition, as a preventative treatment, improves glycemic status, post-ischemic reperfusion in the ischemic territory, and stroke outcome in type 2 diabetic mice.
    PLoS ONE 05/2014; 9(5):e97529. DOI:10.1371/journal.pone.0097529 · 3.23 Impact Factor
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    • "EETs mediate this protection, as inhibition of CYP epoxygenase (the EET synthesis enzyme) prevents sEH benefits (Zhang et al., 2007, 2008). This protective mechanism increases astrocyte survival (Liu and Alkayed, 2005), elevates antiapoptotic factors (Simpkins et al., 2009) and increases neurovascular coupling (Zhang et al., 2007, 2008). Conversely, 20-HETE is elevated during ischemia (Tanaka et al., 2007), and inhibition of 20-HETE production is also neuroprotective in rodent models (Miyata et al., 2005; Poloyac et al., 2006; Tanaka et al., 2007; Dunn et al., 2008; Renic et al., 2009). "
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    ABSTRACT: Dynamic adjustments to neuronal energy supply in response to synaptic activity are critical for neuronal function. Glial cells known as astrocytes have processes that ensheath most central synapses and express G-protein-coupled neurotransmitter receptors and transporters that respond to neuronal activity. Astrocytes also release substrates for neuronal oxidative phosphorylation and have processes that terminate on the surface of brain arterioles and can influence vascular smooth muscle tone and local blood flow. Membrane receptor or transporter-mediated effects of glutamate represent a convergence point of astrocyte influence on neuronal bioenergetics. Astrocytic glutamate uptake drives glycolysis and subsequent shuttling of lactate from astrocytes to neurons for oxidative metabolism. Astrocytes also convert synaptically reclaimed glutamate to glutamine, which is returned to neurons for glutamate salvage or oxidation. Finally, astrocytes store brain energy currency in the form of glycogen, which can be mobilized to produce lactate for neuronal oxidative phosphorylation in response to glutamatergic neurotransmission. These mechanisms couple synaptically driven astrocytic responses to glutamate with release of energy substrates back to neurons to match demand with supply. In addition, astrocytes directly influence the tone of penetrating brain arterioles in response to glutamatergic neurotransmission, coordinating dynamic regulation of local blood flow. We will describe the role of astrocytes in neurometabolic and neurovascular coupling in detail and discuss, in turn, how astrocyte dysfunction may contribute to neuronal bioenergetic deficit and neurodegeneration. Understanding the role of astrocytes as a hub for neurometabolic and neurovascular coupling mechanisms is a critical underpinning for therapeutic development in a broad range of neurodegenerative disorders characterized by chronic generalized brain ischemia and brain microvascular dysfunction.
    Frontiers in Cellular Neuroscience 04/2013; 7:38. DOI:10.3389/fncel.2013.00038 · 4.29 Impact Factor
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    • "Consistent with the previous reports, data in the current study demonstrated that rAAV-CYP2J2 treatment resulted in prolonged elevation of renal CYP2J2 expression and significantly lowered blood pressure in 5/6- nephrectomized rats. In addition, it should be mentioned that inhibition of soluble epoxide hydrolase (sEH) to increase the level of EETs also has an antihypertensive effect, although the effects are model dependent (Fornage et al., 2002; Simpkins et al., 2009). The pathogenesis of hypertension in chronic renal failure is tremendously complex (Klahr and Morrissey, 2003), and the precise molecular mechanisms of EETs on blood pressure control and renal function require further investigation. "
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    ABSTRACT: The cytochrome P450 epoxygenase, CYP2J2, converts arachidonic acid to four regioisomeric epoxyeicosatrienoic acids (EETs), which are highly abundant in the kidney and considered renoprotective. Accumulating evidence suggests that EETs are important in regulating renal and cardiovascular function. Further, EETs have been confirmed to exert diverse biological activities including potent vasodilation; fibrinolytic properties; and antiinflammatory, antiapoptotic, and mitogenic effects. In the current study, we investigated the effects of overexpression of CYP2J2 via recombinant adeno-associated virus (rAAV) in protection against renal damage in a rat 5/6 nephrectomy (5/6-Nx) model of chronic renal failure. The rAAV-CYP2J2 gene delivery in vivo increased EET generation; attenuated the rise in blood pressure; and reduced the levels of proteinuria, serum creatinine, and blood urea nitrogen. Morphological analysis indicated that rAAV-CYP2J2 gene delivery reduced 5/6 nephrectomy-induced glomerular sclerosis, tubular dilatation, luminal protein cast formation, and tubulointerstitial fibrosis. rAAV-CYP2J2 gene delivery also significantly lowered collagen I and IV deposition, as well as renal cell apoptosis detected by TUNEL staining, caspase-3 activity, and the loss of mitochondrial membrane potential (ΔΨ(m)). Furthermore, rAAV-CYP2J2 gene delivery regulated the level of protein expression including transforming growth factor (TGF)-β(1)/SMADs; matrix metalloproteinases (MMPs); mitogen-activated protein kinases (MAPKs); and apoptosis-related proteins Bax, Bcl-2, and Bcl-x(L). Together, these findings demonstrated that rAAV-CYP2J2 gene delivery can protect remnant kidney against renal injury in 5/6-Nx rats by inhibiting apoptosis and fibrosis via regulation of protein expression including TGF-β(1)/SMADs, MMPs, MAPKs, and apoptosis-related proteins.
    Human gene therapy 01/2012; 23(7):688-99. DOI:10.1089/hum.2011.135 · 3.76 Impact Factor
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