20-羟-二十烷四烯酸对血管内皮细胞的作用研究进展

20-羟-二十烷四烯酸(20-hydroxyeicosatetraenoic acid,20-HETE)是花生四烯酸的细胞色素P-450代谢途径的一个重要代谢产物。近年来研究发现20-HETE对血管内皮细胞发挥重要的生理和病理生理作用。20-HETE可激活内皮细胞烟酰胺腺嘌呤二核苷酸(nicotinamide adenine dinucleoti-de phosphate,NADPH)氧化酶系统和核因子-кB(nuclear factor-кB,NF-кB)通路发挥氧化应激和促炎作用;20-HETE可介导血管内皮细胞内皮型一氧化氮合酶(endothelial nitric oxide synthase,eNOS)的解离、降低NO的生物利用度及诱导血管紧张素转换酶,调节血管的舒张和收缩功能;20-HETE还可促进内皮细胞的增生而促进血管新生。但国内对20-HETE研究甚少,因此本文对近年来国际上关于20-HETE对血管内皮细胞的研究作一综述。     

20-羟二十烷四烯酸在机体生理及病理调节中的作用

20多年前,国外学者就报道了机体内某些组织中存在着细胞色素P-450（cytochrome P-450,CYP）。已经证实它能催化花生四烯酸（arachidonic acid,AA）的ω-羟基生成20-羟二十烷四烯酸（20-hydroxyeicosatetraenoic acid,20-HETE）。随着研究的不断深入,人们逐渐发现作为第二信使,20-HETE在调节血管平滑肌紧张度、肾功能、脑血流量和肺血管舒张过程中发挥了重要作用;外源性的20-HETE对心脏冠脉循环也有明显的调节作用;并且它与高血压和妊娠毒血症等疾病的发生和发展关系密切。但国内对于20-HETE的相关研究还鲜有报道,本文将主要就20-HETE在机体生理及病理及病理调节中的作用作一综述。     

花生四烯酸的细胞色素P450酶代谢途径产物EETs和20-HETE在血管功能调控中的作用

花生四烯酸(arachidonic acids, AA)广泛存在于生物体内,并可通过多种途径代谢成为具有强大生物学功能的脂质小分子。其中,经细胞色素P450酶代谢途径产生的环氧二十碳三烯酸(epoxyeicosatrienoic acids, EETs)及20-羟基二十碳四烯酸(20-hydroxyeicosatetraenoic acid, 20-HETE)的作用备受关注,尤其是在血管稳态中的作用。血管功能调控是维持血管稳态的基础,主要通过对血管的结构和(或)生物学活性的影响而实现。近30年来,EETs及20-HETE在血管功能调控中的作用及机制被广泛研究。本文分别就EETs和20-HETE在血管新生和血管炎症反应等方面的研究进展逐一进行综述。总的来说,在生物学活性方面,EETs主要体现为舒张血管和抑制血管炎症,而20-HETE则可以促进血管收缩和血管炎症。两者在血管新生方面的作用类似,都可以促进血管新生。另外,本文还对EETs和20-HETE在常见的血管性疾病(如高血压和心肌缺血)中的作用进行了探讨,对其中的作用机制进行了分析和总结,并对基于EETs和20-HETE的血管性疾病靶向治疗提出了展望。     

可溶性环氧化物水解酶在疾病中的作用

花生四烯酸经过细胞色素P450(cytochrome P450,CYP)表氧化酶途径生成环氧二十碳三烯酸(epoxy eicosatrienoic acid,EETs),具有扩张血管、降低血压、抗炎等多种生物学功能。在哺乳动物系统中的可溶性环氧化物水解酶（soluble epoxide hydrolase,sEH)具有α/β水解酶折叠结构,对环氧脂肪酸具有高度的选择性。sEH能够快速水解EETs,增加患心血管疾病的风险。目前,研究发现sEH抑制剂具有抑制sEH活性、提高EETs的含量的重要功能。 在多种疾病动物模型中应用sEH抑制剂或sEH基因敲除,证实sEH在心肌肥厚、糖尿病、高血压和肾病等疾病中发挥重要的生理作用。因此,sEH已被作为疾病治疗的新靶点而进行研究。本文就sEH的分布、作用机制以及sEH与疾病的关系等方面进行了讨论。     

花生四烯酸细胞色素P450表氧化酶代谢物EETs的内源性心血管保护作用

花生四烯酸(arachidonic acid, AA)是生物体内最丰富的多不饱和脂肪酸,其代谢产物具有广泛的生物学活性。环氧二十碳三烯酸(epoxyeicosatrienoic acids, EETs)是AA经细胞色素P450表氧化酶(cytochrome P450 epoxygenase, CYP450)代谢产生的内源性小分子化合物,近20年的研究表明EETs具有广泛的心血管保护作用,是重要的内源性心血管保护因子。EETs不仅可以改善不同病因导致的心脏重构,抑制心肌肥厚,减轻不同因素导致的心肌损伤,还能明显改善上述病理过程所导致的血流动力学紊乱和心功能损害。在血管保护方面,最早的研究证明EETs是一种内皮来源的超极化因子,可以通过作用于内皮细胞和平滑肌上的钙离子敏感通道而发挥血管舒张作用,随后研究发现,EETs可能有更多非超极化效应而产生降压、改善冠状动脉血供、调节肺动脉压力等作用。此外,EETs还具有显著的内皮保护效应,可以抑制内皮细胞的炎症反应和黏附作用,抑制血小板聚集,促进纤溶和血管的新生。EETs还能改善主动脉重构,包括抑制动脉粥样硬化、主动脉外膜纤维化和主动脉钙化。EETs心血管保护作用的分子机制是多方面的,EETs可通过调控多个信号通路从而调节不同病理生理环节,是一种多靶点内源性心血管保护因子。因此研究EETs在心血管系统中的生理和病理生理作用有利于阐明心血管疾病的内源性保护机制,为心血管疾病的防治提供新策略。本文综述了EETs的内源性心血管保护作用和机制,以期为该领域的转化研究提供新的思路。     

花生四烯酸细胞色素P450代谢物在肾脏生理和疾病中的作用(英文)

肾脏疾病在全球范围内都是导致死亡的重要原因。肾脏微血管功能失调在肾病的发生与发展中发挥着不可忽视的作用。药理学和生物化学等领域的许多实验方法已被用来研究花生四烯酸的细胞色素P450 (cytochrome P450, CYP450)代谢物对肾脏微血管功能的调控作用。在肾脏中,CYP450表氧化酶代谢物环氧二十碳三烯酸(epoxyeicosatrienoic acids, EETs)主要在肾脏微血管产生。EETs可以通过舒张血管、降低血压、抗细胞凋亡、抗炎等多个方面发挥肾脏保护作用。CYP450表氧化酶代谢物EETs可作为肾脏疾病的治疗靶点。然而,在肾脏发生疾病时,肾脏微血管产生EETs的能力会显著降低。近来,用转基因动物过表达CYP450表氧化酶或用可溶性环氧化物水解酶(soluble epoxide hydrolase, sEH)抑制剂也均证实增加EETs水平具有明显的肾脏保护作用。本综述将重点讨论花生四烯酸的CYP450代谢物EETs在肾脏生理及疾病状态下具体的调控机制。     

花生四烯酸Alox15/12-HETE代谢通路抑制血管钙化的发生

本研究旨在探索血管钙化中花生四烯酸脂氧酶代谢产物的变化及作用。采用5/6肾切除及高磷饲喂的方法建立小鼠血管钙化的模型。在造模6周后,检测主动脉全长血管钙含量,主动脉弓部进行茜素红染色和Von Kossa染色检测钙沉积情况。收集对照血管和钙化血管组织进行花生四烯酸代谢产物的质谱检测,分析脂氧酶通路代谢小分子的变化。通过实时定量PCR方法检测钙化血管脂氧酶的表达改变。使用脂氧酶抑制剂明确脂氧酶代谢通路对血管钙化的影响。结果显示,造模6周后,肾切除组小鼠血管钙含量比假手术组显著升高(P 0.05),茜素红染色和Von Kossa染色显示肾切除小鼠主动脉弓部有明显的钙沉积,表明小鼠血管钙化造模成功。收取造模6周的钙化血管和对照血管,通过液相色谱-质谱(LC-MS)方法检测到9种花生四烯酸脂氧酶代谢产物,多种代谢产物(12-HETE、11-HETE、15-HETE等)的含量在钙化血管中显著升高,其中12-HETE含量最高并且升高最显著。进一步检测钙化血管中产生12-HETE的代谢酶的mRNA水平,发现花生四烯酸脂氧酶15(arachidonate 15-lipoxygenase, Alox15)表达增加。Alox15特异性抑制剂PD146176可显著降低血浆12-HETE水平,促进主动脉弓部的钙沉积、增加血管钙含量。这些结果显示花生四烯酸脂氧酶代谢在钙化血管中活化,Alox15/12-HETE通路可能对血管钙化发挥保护作用。     

花生四烯酸的生物活性及其钙信号转导作用

花生四烯酸（arachidonic acid,AA）以酯化形式在膜磷脂中,细胞兴奋时多种信号转导途径可引起游离AA释放,并迅速代谢为具有生物活性的炎症物质,参与细胞免疫和炎症反应。目前大量研究表明,AA本身还直接参与细胞内生物功能的调节,包括影响酶功能,调控各种离子通道,尤其是直接导致细胞内信号转导,成为细胞膜受体兴奋－细胞内生物反应偶联的第二信使。但AA的作用机制及其生理和病理生理意义有待进一步研究。     

ERK1/2通路参与15-羟二十碳四烯酸收缩缺氧大鼠肺动脉的过程

缺氧诱导的15-羟二十碳四烯酸（15-hydroxyeicosatetraenoic acid,15-HETE）是引起肺动脉收缩的重要介导因子。15-HETE引起肺动脉收缩的信号转导途径尚不清楚。本研究旨在确定细胞外信号调节激酶1／2（extracellular signal-regulated kinase-1／2,ERK1／2）信号转导通路是否参与15-HETE收缩缺氧火鼠肺动脉的过程。采用组织浴槽肺动脉环张力检测、蛋白质免疫印迹Western blot）和免疫细胞化学方法。制备缺氧大鼠动物模型,成年雄性Wistar大鼠在低氧环境下（吸入氧分数为0．12）正常喂养9d。显微分离直径1-1．5mm肺动脉,剪成长为3mm的动脉环,进行血管张力检测。用ERK1／2上游激酶（MEK）抑制剂PD98059抑制ERK1／2活性。结果显示,PD98059可明显抑制15-HETE对缺氧大鼠肺动脉环的收缩作用。在去除内皮的肺动脉环,PD98059仍叮明显降低15-HETE的缩血管作用。Western blot和免疫细胞化学结果都显示,15-HETE能促进ERK1／2磷酸化。由此表明ERK1／2信号转导通路参与15-HETE收缩缺氧大鼠肺动脉的过程。     

花生四烯酸代谢与肝脏糖脂代谢稳态调控

花生四烯酸(arachidonic acid, AA)是一种ω-6多不饱和脂肪酸,在生物体内主要是以磷脂的形式存在于细胞膜上。AA在细胞内主要通过环氧合酶(cyclooxygenase, COX)途径、脂氧合酶(lipoxygenases, LOX)途径、细胞色素P450单氧化酶(cytochrome P450 monooxygenase, CYP450)途径等进行代谢。糖脂代谢的稳态调控是维持机体基本生命活动的基础,肝脏是糖脂代谢调控的中枢器官。肝脏糖脂代谢紊乱与2型糖尿病、非酒精性脂肪性肝病等代谢性疾病的发生和发展密切相关。已有研究表明AA代谢与肝脏糖脂代谢紊乱有密切的关系。本文就AA代谢在肝脏糖脂代谢稳态调控中的作用及其作为脂肪肝和胰岛素抵抗等代谢性疾病治疗靶点的价值作一综述。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.