Role of P-450 arachidonic acid epoxygenase in the response of cerebral blood flow to glutamate in rats
Role of P-450 arachidonic acid epoxygenase in the response of cerebral blood flow to glutamate in rats
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DOI：
10.1161/01.str.28.5.1066
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发表时间：
1997-05-01
期刊：
影响因子：
8.3
通讯作者：
Harder, DR
中科院分区：
文献类型：
--
作者：
Alkayed, NJ;Birks, EK;Harder, DR
背景和目的谷氨酸是大脑中主要的兴奋性神经递质，与神经元活性增加的高血症反应有关，但是谷氨酸引起的大脑血管扩张的机制尚不清楚。已显示谷氨酸可以增强脑组织和培养的星形胶质细胞中花生四烯酸（AA）的释放。我们先前已经表明，星形胶质细胞将AA代谢为血管舒张产物，环氧酸性酸（EET）和表达P-450 AA环氧酶P-450 2C11。我们检验了以下假设：谷氨酸诱导的脑小动物的扩张部分是通过血管周围星形胶质细胞的形成和EET释放的部分介导的。方法是从3天老鼠幼崽中制备的主要星形胶质细胞培养物。用[C-14] AA标记细胞，并研究了谷氨酸对培养的星形胶质细胞从[C-14] AA形成Eets的影响。通过Western印迹评估了培养的星形胶质细胞微粒体馏分中P-450 2C11蛋白的表达。用谷氨酸给予谷氨酸后，用激光多普勒流量指定在成年大鼠中进行体内脑血流量测量，并在用米诺唑治疗前后，将谷氨酸的下和硬膜下空间进行。谷氨酸治疗（100 mu mol/l）诱导了三倍的谷氨酸治疗通过培养的星形胶质细胞从[C-14] AA的EET形成增加，并被米诺唑抑制了增加（20 Mu Mol/L），P-450 AA环氧酶的抑制剂。用谷氨酸（100 mu mol/L）处理12小时，在培养的星形胶质细胞的微粒体分数中，P-450 2C11蛋白的表达增加了。用链甲唑处理后，激光多普勒脑血流对谷氨酸（500 mu mol/l）对大鼠的下膜空间的施用显着减弱（20次mu mol/l 30分钟）。 P-450 AA环氧酶在星形胶质细胞中的作用在神经元的代谢活性与区域血流之间的耦合中的作用 脑。
Background and Purpose Glutamate, a major excitatory neurotransmitter in the brain, has been implicated in the hyperemic response to increases in the activity of neurons, but the mechanism of glutamate-induced dilation of cerebral blood vessels is unknown. Glutamate has been shown to enhance the release of arachidonic acid (AA) in brain tissue and cultured astrocytes. We have previously shown that astrocytes metabolize AA to vasodilator products, epoxyeicosatrienoic acids (EETs), and express a P-450 AA epoxygenase, P-450 2C11. We tested the hypothesis that glutamate-induced dilation of cerebral arterioles is mediated in part by changes in the formation and release of EETs by perivascular astrocytes.Methods Primary astrocyte cultures were prepared from 3-day-old rat pups. The cells were labeled with [C-14]AA, and the effect of glutamate on the formation of EETs from [C-14]AA by cultured astrocytes was studied. The expression of P-450 2C11 protein in the microsomal fractions of cultured astrocytes was assessed by Western blot. In vivo cerebral blood flow measurements were made in adult rats by laser-Doppler flowmetry after administration of glutamate into the subdural space of the rat before and after treatment with miconazole.Results Glutamate treatment (100 mu mol/L for 30 minutes) induced a threefold increase in the formation of EETs from [C-14]AA by cultured astrocytes, and the increase was inhibited by miconazole (20 mu mol/L), an inhibitor of P-450 AA epoxygenase. Treatment with glutamate (100 mu mol/L) for 12 hours increased the expression of P-450 2C11 protein in the microsomal fraction of cultured astrocytes. The response of laser-Doppler cerebral blood flow to administration of glutamate (500 mu mol/L) into the subdural space of the rat was significantly attenuated after treatment with miconazole (20 mu mol/L for 30 minutes).Conclusions These findings suggest a role for a P-450 AA epoxygenase in astrocytes in the coupling between the metabolic activity of neurons and regional blood flow in the brain.