NADPH氧化酶在高脂诱导的人脐静脉血管内皮细胞氧化应激损伤中的作用

目的探讨NADPH氧化酶在高脂诱导的人脐静脉血管内皮细胞(human umbilical vein endothelial cells,HUVECs)氧化应激损伤中的作用。方法不同浓度(0.1、0.2、0.4、0.8 mmol·L~(-1))棕榈酸(palmitic acid,PA)刺激HUVECs 0、12、24、48 h,CCK-8法检测血管内皮细胞增殖能力;免疫印迹法检测血管内皮细胞NADPH氧化酶亚基p22phox、p47phox、p67phox、gp91phox的表达水平;免疫荧光法检测血管内皮细胞细胞内活性氧簇(reactive oxygen species,ROS)的表达水平。结果 0.4 mmol·L~(-1)PA刺激HUVECs 24、48 h组的细胞增殖率出现明显降低。因此,实验中我们采用0.4 mmol·L~(-1)PA刺激24 h作为模型组;0.4 mmol·L~(-1)PA刺激HUVECs24、48 h时,p22phox、p47phox、p67phox、gp91phox的表达均明显升高(P<0.05),24 h组与48 h组差异不明显(P>0.05);0.4mmol·L~(-1)PA刺激血管内皮细胞24、48 h时,细胞内ROS表达水平均明显增高(P<0.05),24 h组与48 h组差异不明显(P>0.05);与模型组(0.4 mmol·L~(-1)PA刺激24 h)相比,NADPH氧化酶抑制剂diphenyliodonium(DPI,10μmol·L~(-1))预处理可以使模型组血管内皮细胞ROS表达水平明显下调(P<0.05)。结论 NADPH氧化酶活性对高脂所致血管内皮细胞氧化应激损伤的防治有重要意义。     

内质网应激信号通路在高脂诱导的心肌细胞损伤中的作用

目的探讨内质网应激信号通路在高脂诱导的心肌细胞损伤中的作用。方法棕榈酸(0.1~0.4 mmol·L~(-1))刺激心肌细胞(0~48 h),CCK-8法评估细胞生长状态,免疫印迹法评估细胞内内质网应激信号通路相关蛋白表达水平及细胞凋亡蛋白表达水平。结果棕榈酸(0.1~0.4 mmol·L~(-1))刺激H9C2心肌细胞24 h,0.2、0.4 mmol·L~(-1)组细胞增殖率均出现明显下降。棕榈酸(0.2 mmol·L~(-1))刺激H9C2心肌细胞时,24、48 h组细胞增殖率均出现明显下降。棕榈酸(0.2 mmol·L~(-1))刺激24 h,GRP78、CHOP、PERKphos、IRE1phos、ATF6等内质网应激相关蛋白及Bax蛋白表达均明显增高(P<0.05),而Bcl-2表达出现明显降低(P<0.05)。预处理内质网应激抑制剂普伐他汀(pravastatin,10mol·L~(-1))的棕榈酸(0.2 mmol·L~(-1))组与不加pravastatin的棕榈酸(0.2 mmol·L~(-1))组相比,Bcl-2及Bax的表达均恢复至正常水平。结论内质网应激信号通路对高脂引起的心肌损伤的发病及治疗均起到重要作用。     

高脂通过线粒体通路诱导H9c2心肌细胞损伤

目的探讨高脂通过线粒体凋亡通路对H9c2心肌细胞的损伤作用。方法棕榈酸(0～0.4 mmol·L~(-1))刺激H9c2心肌细胞24 h和0.2 mmol·L~(-1)棕榈酸刺激H9c2心肌细胞(0～48 h);MTT法评估细胞生长状态;活性氧试剂盒检测细胞内活性氧水平;凋亡试剂盒检测细胞凋亡情况;线粒体膜电位试剂盒检测线粒体膜电位变化;免疫印迹法检测细胞内线粒体凋亡相关蛋白Cyt-C、Cleaved casepase-3、Bax、Bcl-2表达水平。结果棕榈酸刺激H9c2心肌细胞24 h,棕榈酸0.2、0.4 mmol·L~(-1)组细胞增殖率均出现明显下降;细胞内活性氧水平逐渐升高,线粒体膜电位下降,细胞凋亡增加。棕榈酸(0.2 mmol·L~(-1))刺激H9c2心肌细胞24、36、48 h均引起细胞增殖率明显下降。棕榈酸(0.4 mmol·L~(-1))刺激H9c2心肌24 h,线粒体相关蛋白Cyt-C、Cleaved casepase-3、Bax表达均明显增高(P <0. 05),而Bcl-2明显降低(P <0. 05)。结论线粒体凋亡信号通路可能对高脂所致H9c2心肌细胞损伤起重要作用。     

内质网应激信号通路在棕榈酸诱导的血管内皮细胞凋亡中的作用

目的探讨内质网应激(endoplasmic reticulum stress,ERS)信号通路在棕榈酸诱导的人脐静脉血管内皮细胞(human umbilical vein endothelial cells,HUVECs)凋亡中的作用。方法不同浓度(0.1、0.2、0.4、0.8 mmol·L~(-1))棕榈酸刺激HUVECs(0、12、24、48 h),CCK-8法检测血管内皮细胞增殖能力;免疫印迹法检测血管内皮细胞GRP78、CHOP、PERK、IRE1、ATF6等ERS信号通路蛋白的表达水平;免疫荧光法检测细胞内凋亡水平。结果 0.4 mmol·L~(-1)棕榈酸刺激血管内皮细胞24 h,细胞增殖率明显降低;GRP78、CHOP、PERK、IRE1、ATF6等ERS信号通路蛋白的表达明显升高(P<0.05),细胞凋亡水平明显增高(P<0.05);ERS抑制剂4-苯基丁酸(4-PBA,10 mmol·L~(-1))预处理组血管内皮细胞凋亡水平明显下调(P<0.05)。结论 ERS信号通路在棕榈酸所致血管内皮细胞凋亡的防治中有重要意义。     

ATP敏感性钾通道-Akt通路在硫化氢对抗高糖损伤H9c2心肌细胞中的作用

目的研究ATP敏感性钾通道(ATP-sensitive K+channel,KATP通道)-Akt通路在外源性硫化氢(hydrogen sulfide,H_2S)对抗高糖引起的H9c2心肌细胞损伤中的作用。方法应用Western blot法检测心肌细胞Akt蛋白的表达水平;细胞计数盒测定心肌细胞存活率;Hoechst 33258核染色荧光显微镜照相测定凋亡细胞数量的变化;双氯荧光素染色荧光显微镜照相法检测胞内活性氧(reactive oxygen species,ROS)水平;JC-1染色荧光显微镜照相法测定线粒体膜电位(mitochondrial membrane potential,MMP)。结果应用高糖(35 mmol·L~(-1),HG)处理H9c2心肌细胞0~24 h,其中3 h起磷酸化(p)-Akt蛋白表达水平开始明显下降,24 h p-Akt表达水平降至最低。在HG处理心肌细胞24 h前,应用50μmol·L~(-1)KATP通道开放剂吡拉地尔(pinacidil,Pin)和400μmol·L~(-1)硫氢化钠(NaHS,为H_2S的供体)预处理30 min均能明显地抑制HG对p-Akt表达的下调作用。应用1mmol·L~(-1)K_(ATP)通道阻断剂格列本脲(glibenclamide,Gli)预处理心肌细胞能阻断NaHS对HG下调p-Akt表达水平的抑制作用。此外,30μmol·L~(-1)Akt的抑制剂LY294002能明显阻断NaHS对抗HG损伤心肌细胞的保护作用,表现为细胞存活率和MMP降低,凋亡细胞数量、ROS生成增多。结论 K_(ATP)通道-Akt通路介导H_2S对抗高糖引起的心肌细胞损伤的保护作用。     

坏死性凋亡和p38 MAPK通路的相互作用介导高糖引起的H9c2心肌细胞损伤

目的研究坏死性凋亡(necroptosis,Nec)和p38丝裂原激活蛋白激酶(mitogen-activated protein kinase,MAPK)通路的相互作用在高糖引起H9c2心肌细胞损伤中的作用。方法应用细胞计数盒检测心肌细胞存活率;双氯荧光素染色荧光显微镜照相法检测细胞内活性氧(reactive oxygen species,ROS)水平;罗丹明123染色荧光显微镜照相法测定线粒体膜电位(mitochondrial membrane potential,MMP);蛋白质免疫印迹法测定RIP3蛋白(反映Nec的指标)和p38MAPK蛋白的表达水平。结果高糖(35 mmol·L~(-1)葡萄糖,HG)作用H9c2心肌细胞24 h可引起明显的细胞损伤,表现为细胞存活率降低,ROS生成及MMP丢失增多;应用100μmol·L~(-1)necrostatin-1(Nec-1,Nec特异性抑制剂)和HG共处理心肌细胞24 h或3μmol·L~(-1)SB203580(p38MAPK抑制剂)预处理心肌细胞60 min,再予HG作用24 h可减轻高糖引起的上述损伤。此外,HG作用心肌细胞1、3、6、9、12、24、36和48 h均能明显增加RIP3蛋白的表达水平,其中24 h时表达水平增加最明显。应用100μmol·L~(-1)Nec-1共处理或3μmol·L~(-1)SB203580预处理心肌细胞均能明显地抑制HG对RIP3蛋白表达的上调作用。另一方面,应用100μmol·L~(-1)Nec-1共处理心肌细胞能阻断HG对磷酸化(p)-p38MAPK表达的上调作用。结论 Nec和p38 MAPK通路的相互作用介导高糖引起H9c2心肌细胞损伤。     

2型糖尿病大鼠心肌PI3K/Akt/mTOR信号通路的改变及Sirt1的调控机制研究

目的检测Sirt1及PI3K/Akt/mTOR信号通路相关蛋白在糖尿病大鼠心肌及高糖培养的H9C2细胞中的表达变化,明确其在糖尿病心肌病发生发展中的作用。方法高脂饮食联合链脲佐菌素建立2型糖尿病大鼠模型,实验将大鼠分为糖尿病2周、4周、8周模型组和对照组,超声心动图检测大鼠心功能变化,Western blot检测大鼠心肌Sirt1、PI3K、Akt、mTOR、S6K1蛋白表达变化。将H9C2细胞分为正常对照组、DMSO组(78.12 mmol·L~(-1))、高糖(HG)组(33 mmol·L~(-1))、白藜芦醇(Res)组(20μmol·L~(-1))、尼克酰胺(Nam)组(40 mmol·L~(-1)),Western blot及qRT-PCR研究心肌细胞Sirt1、PI3K、Akt、mTOR、S6K1相关蛋白基因转录及表达,研究Sirt1对该信号通路的调控机制。结果在动物实验中,与2周DM大鼠比较,8周DM大鼠心肌Sirt1蛋白表达明显增加。2周模型组大鼠相对于正常对照组心肌PI3K、Akt、mTOR、S6K1表达明显增加,且S6K1表达4周模型组比2周模型组增加更明显,但8周表达降低。在高糖培养的H9C2细胞中,与对照组相比,高糖组Sirt1,PI3K,Akt,mTOR和S6K1表达明显增高。Nam处理组Sirt1表达明显降低,PI3K,Akt,mTOR和S6K1表达增高。Res处理组Sirt1表达明显增高,而PI3K,Akt,mTOR和S6K1表达降低。结论 Sirt1通过负调控PI3K/Akt/mTOR信号通路参与糖尿病心肌损伤,参与早期糖尿病心肌病的发生发展。     

线粒体凋亡通路在棕榈酸诱导的血管内皮细胞凋亡中的作用

目的探讨线粒体凋亡通路在棕榈酸诱导的人脐静脉血管内皮细胞(human umbilical vein endothelial cells,HUVECs)凋亡中的作用。方法不同浓度棕榈酸(0.1、0.2、0.4、0.8 mmol·L~(-1))作用HUVECs(0、12、24、48 h),MTT法检测HUVECs增殖能力;免疫荧光法检测HUVECs细胞内活性氧(reactive oxygen species,ROS)的表达水平;免疫印迹法检测HUVECs中AIF、Cyt-C、cleaved caspase-3、Bcl-2、Bax等线粒体凋亡通路蛋白的表达水平;TUNEL法检测细胞内凋亡水平。结果 0.4 mmol·L~(-1)棕榈酸作用HUVECs 24 h时,细胞增殖率明显降低;AIF、Cyt-C、cleaved caspase-3、Bax/Bcl-2的水平明显升高(P<0.05),细胞凋亡水平明显增高(P<0.05);线粒体通透性抑制剂环孢素A (ciclosporine A, CsA)预处理组HUVECs凋亡水平明显下调(P<0.05)。结论棕榈酸所致血管内皮细胞损伤的发病机制可能与线粒体凋亡相关通路密切关联,此研究对脂毒性心肌损伤的防治有重要意义。     

TGF-β/Smads信号通路在姜黄素改善糖尿病大鼠心肌纤维化中的作用

目的探讨TGF-β/Smads信号通路在姜黄素改善糖尿病心肌纤维化中的作用。方法高糖高脂饮食联合腹腔注射小剂量链脲佐菌素(STZ)35 mg·kg~(-1)建立2型糖尿病大鼠模型,自由饮用300 mg·kg·d~(-1)姜黄素进行干预;天狼猩红染色检测各组大鼠心肌内胶原表达情况;免疫荧光检测各组大鼠心肌内CollagenⅠ和CollagenⅢ的表达情况;葡萄糖(5.5、20、25、30、35、50 mmol·L~(-1))刺激大鼠乳鼠心肌成纤维细胞(CFs)24 h确定最佳高糖造模浓度;30 mmol·L~(-1)高糖加姜黄素(10、25、50、100、200μmol·L~(-1))刺激CFs 24h确定最佳姜黄素给药浓度;Western blot法检测细胞内CollagenⅠ、CollagenⅢ、TGF-β1、p-Smad2、Smad2、p-Smad3、Smad3、TβR-Ⅲ的蛋白表达水平。结果相比于正常组,糖尿病组大鼠心肌组织胶原出现明显沉积,CollagenⅠ和CollagenⅢ表达明显增多,给予姜黄素治疗后,糖尿病大鼠心肌组织胶原沉积明显减少,CollagenⅠ和CollagenⅢ表达明显减少;30 mmol·L~(-1)高糖刺激CFs 24 h可以明显促进细胞增殖(P<0.05);而10μmol·L~(-1)姜黄素可以明显抑制高糖诱导的CFs增殖(P<0.05);30 mmol·L~(-1)高糖诱导CFs24 h以后,CollagenⅠ、CollagenⅢ、TGF-β1、p-Smad2、pSmad3、TβR-Ⅲ的蛋白表达明显增多(P<0.05),给予25μmol·L~(-1)姜黄素以后,上述各蛋白表达水平明显下降(P<0.05)。结论姜黄素可通过TGF-β/Smads信号通路改善糖尿病大鼠心肌纤维化,对糖尿病大鼠心肌具有保护作用。     

GLP-1对AGEs诱导H9C2心肌细胞凋亡的保护作用研究

目的研究胰高血糖素样肽素-1(glucogon like pep tide-1,GLP-1)对晚期糖基化终产物(advanced glycation end products,AGEs)诱导H9C2心肌细胞凋亡的保护作用机制。方法体外培养H9C2细胞,实验分为4组:正常对照组、100 mg·L~(-1)AGEs试验组、AGEs(100 mg·L~(-1))+GLP-1(10 nmol·L~(-1))组、AGEs(100 mg·L~(-1))+NAC(5 mmol·L~(-1))组,处理24 h。通过CCK-8比色法检测细胞存活率,相差显微镜观察细胞形态,双氯荧光素(DCFH-DA)染色荧光显微镜摄片观察细胞内活性氧(ROS)水平;RT-PCR法测定Bax、Bcl-2 mRNA基因的表达;运用Hoechst 33258检测试剂盒及流式细胞术检测心肌细胞的凋亡率,Western blot检测凋亡相关蛋白Bax、Bcl-2的表达量。结果与正常组相比,100 mg·L~(-1)AGEs组降低H9C2细胞生存率,活性氧(ROS)生成量增加;与AGEs组相比,AGEs+GLP-1组细胞生成率提高,活性氧(ROS)生成量减少。与正常组相比,AGEs组促凋亡蛋白Bax表达增加,抑制凋亡蛋白Bcl-2减少,细胞凋亡率升高;AGEs+GLP-1组较AGEs组下调促凋亡蛋白Bax,上调凋亡抑制蛋白Bcl-2,细胞凋亡率减少。结论 GLP-1对AGEs诱导的心肌细胞凋亡具有保护作用,其保护机制与减少活性氧(ROS)有关。     

Clevudine University of Georgia/Abbott/Bukwang/Triangle/Yale University

The pyrimidine analog, clevudine (L-FMAU: 2'-fluoro-5-methyl-beta-L-arabinofuranosyluridine) is a potent antihepatitis B virus (HBV) and anti-Epstein-Barr virus (EBV) agent, discovered by researchers at the University of Georgia, in collaboration with Yale University and Bukwang. Bukwang transferred its technology to Triangle Pharmaceuticals in 1998 together with a license to develop clevudine worldwide except Korea [279649], [281942]. In June 1999, Triangle and Abbott Laboratories entered into a strategic alliance to copromote antiviral products including L-FMAU [326798]. In September 2000, Triangle Pharmaceuticals Inc initiated a 30-day phase I/II evaluation of clevudine in HBV-infected patients [381755]. Clevudine is a much less toxic derivative of the toxic agent P-D-FMAU. The mechanism of action of clevudine is not yet clear, but the agent induces a rapid decrease in HBV nucleic acid as doses increase from 0.3 to 10 mg/kg [319145]. It is believed that the target for clevudine lies in the viral replication mechanism. Clevudine is phosphorylated to the triphosphate form intracellularly. This is removed slowly from the cells, thus exerting a sustained inhibitory antiviral activity [178173], [320720], [320721].     

Spotlight from the American Society for Preventive Cardiology on Key Features of the 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guidelines on the Management of Blood Cholesterol

The 2018 AHA/ACC/AACVPR/AAPA/ABC/ACPM/ADA/AGS/APhA/ASPC/NLA/PCNA Guideline on the Management of Blood Cholesterol retains focus on recommendations for statin treatment in the original four statin-eligible groups [those with atherosclerotic cardiovascular disease (ASCVD), diabetes, low-density lipoprotein cholesterol (LDL-C) ≥ 190 mg/dL, and higher risk primary prevention] without the use of treatment initiation or target LDL-C levels from the earlier 2013 American College of Cardiology/American Heart Association (ACC/AHA) guideline, but has several new features. First, patients with primary prevention are divided into those who are at low (< 5%), borderline (5% to < 7.5%), intermediate (7.5% to < 20%), and high (≥ 20%) risk based on the ASCVD risk estimator. Moreover, the new guideline goes further to consider a wider range of factors [now called “risk enhancers”—premature family history of ASCVD, persistently high LDL-C, chronic kidney disease (CKD), metabolic syndrome, conditions specific to women, inflammatory diseases, and high-risk ethnicities] that can be used to better inform the treatment decision. Moreover, more detailed recommendations on how the results of coronary calcium scanning can be used to inform the treatment decision are provided, including how it may be used to “de-risk” certain patients for delaying or avoiding the use of statin therapy. There are also specific sections for cholesterol management in other patient subgroups including women, children, certain ethnic groups, those with CKD, chronic inflammatory disorders and HIV, as well as discussion on the management of hypertriglyceridemia. Importantly, for persons with known ASCVD, a distinction is made for those who are at “very high risk” based on having had two major ASCVD events or one major event and two or more other high risk conditions, such as diabetes or other major risk factors, or bypass surgery or percutaneous intervention. Finally, the concept of a threshold LDL-C for initiating a non-statin therapy (after considering highest tolerated statin dosage) is provided, with ezetimibe recommended as the key non-statin to be added if the LDL-C still remains ≥ 70 mg/dL for all ASCVD patients, and in those who are at “very high risk”, further consideration for using a proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor. While the new guideline does have greater detail (and arguably, complexity), the refinements provide a strategy for guiding the clinician to target both statin and non-statin therapy to those most likely to derive benefit.     

Cerebral metabolism of [3H]-p-chloroamphetamine

The time-dependent metabolism of intraventricularly administered $\text{[}{}^3\text{H}\text{]-p-}\text{chloroamphetamine}$ was followed. The parent compound and its metabolites were recovered by high pressure liquid chromatography and characterized by high pressure liquid chromatography, thin-layer chromatography, and gas chromatography-mass spectrometry. By 4 hr after injection, two major toluene-soluble metabolites were present in brain. Their biological half-lives were different from the parent compound. On the basis of their analyses, one of the metabolites is p-chloronorephedrine, the other (P₃) is as yet unidentified. Pretreatment with Lilly 110140 prevented or markedly reduced the synthesis of both p-chloronorephedrine and P₃. Iprindole prevented the synthesis of p-chloronorephedrine. The P₃ appeared first in the brain then in the liver, suggesting that both of these organs can metabolize p-chloroamphetamine to this compound. The metabolites were recovered primarily from the nuclear and microsomal fractions following subcellular fractionation of the brain, with small quantities present in the synaptosomal fraction. The level of metabolites was higher in the brainstem than in the neocortex. Glutathione, administered simultaneously with p-chloroamphetamine either intraventricularly or intraperitoneally failed to alter the toxicity of p-chloroamphetamine.     

Conversion of the N-O-glucuronide and N-O-sulfate conjugates of N-hydroxyphenacetin to reactive intermediates

The N-O-glucuronide of [¹⁴C]acetyl-N-hydroxyphenacetin is sufficiently stable to purify, but slowly breaks down in aqueous solutions to a reactive intermediate that can covalently bind to protein. When the pure compound was incubated in Tris buffer, pH 7.4, at 37°, it decomposed with a half-life of about 8.7 hr to the following compounds: phenacetin, 2-hydroxyphenacetin glucuronide, acetamide and acetaminophen. On addition of glulathione to the systems and allowing the reactions to go to completion, a glutathione-acetaminophen conjugate was formed at the expense of acetamide and acetaminophen: the fraction converted to phenacetin or to the 2-hydroxyphenacetin glucuronide was unchanged. On addition of ascorbic acid to the system and allowing the reactions to go to completion, the fraction converted to acetaminophen was increased at the expense of acetamide: the fractions converted to phenacetin and 2-hydroxyphenacetin glucuronide, however, were again unchanged. When the glucuronide was incubated with bovine serum albumin, covalent binding to the protein occurred at the expense of acetaminophen and acetamide; again, the fraction of the glucuronide converted to phenacetin and 2-hydroxyphenacetin glucuronide was unchanged. Moreover, the covalent binding could be partially prevented by addition of ascorbic acid or glutathione. Since there is formation of covalently bound material, the glutathione conjugate and acetaminophen appear to be interrelated; it seems likely that they are formed from a common intermediate, possibly acetylimidoquinone. However, the data suggest that the formation of phenacetin and 2-hydroxyphenacetin glucuronide occurs by different mechanisms. The N-O-sulfate of [¹⁴C]acetyl-N-hydroxyphenacetin also breaks down to a reactive intermediate that has properties similar to those of the reactive intermediate formed from the N-O-glucuronide and thus may also be N-acetylimidoquinone. By contrast, the relative ability of various nucleophiles to prevent the covalent binding of the reactive intermediate formed from the N-O-sulfate of 2-acetylaminofluorene to protein differs from the relative ability of the nucleophiles to prevent the covalent binding of the reactive intermediate of either the N-O-sulfate or the N-O-glucuronide of phenacetin, suggesting that the relative rates at which these intermediates combine with the different macromolecules may differ markedly.     

甘草配伍大戟的体外肝毒性研究

目的 研究甘草和大戟配伍的体外肝毒性。方法 采用显微观察法和MTT法检测不同浓度的甘草单煎液、大戟单煎液、甘草-大戟合煎液和甘草-大戟单煎混合液对人肝癌细胞HepG2增殖的影响,并比较大戟单煎液、甘草-大戟合煎液和甘草-大戟单煎混合液相当浓度下细胞毒性的大小。结果 大戟单用及大戟与甘草配伍均有细胞毒性,且呈剂量相关性;与大戟单煎液相比,甘草-大戟单煎混合液细胞毒性无明显差异,甘草-大戟合煎液细胞毒性减小。结论 甘草和大戟配伍导致大戟的体外肝毒性减小。     

刺五加的研究进展

刺五加含有苷类、黄酮、多糖等多种活性成分,具有免疫调节、抗肿瘤、抗衰老、抗疲劳等药理作用。对国内外刺五加相关文献进行总结,为刺五加进一步的研究和开发提供参考资料。     

Structure-activity relationships of met5- and leus-enkephalin analogues

1. The effect of various analogues of met5- and leu5-enkephalin were determined on the reduction in twitch height of the electrically-stimulated longitudinal muscle preparation of the guinea-pig ileum and of the isolated mouse vas deferens. 2. In the guinea-pig ileum, D-alanine2-met5-enkephalin was the most potent whereas leu5-enkephalin was the most potent in the mouse vas deferens. 3. The met5-enkephalin analogues were more effective in reducing the twitch height of the ileum than they were in depressing that of the vas deferens preparation. The leu5-enkephalin analogues were more potent in their effects on the mouse vas deferens than they were on the guinea-pig ileum. 4. When a peptide bond is replaced by a glycol bond as in glycol2-3-leu5-enkephalin there is a marked reduction in opiate-like activity. 5. Substitution of a D-alanine residue for the glycine2 residue, as in D-alanine2-met5-enkephalin, increases the duration and potency of opiate-like activity. 6. These results confirm that modification of either met5- or leu5-enkephalin can alter the opiate-like potency of the resulting analogues. It appears that an intact tyrosyl residue of leu5-enkephalin is essential for such activity and that substitution of a D-alanine2 residue for the glycine2 residue confers resistance to enzymatic degradation on the met5-enkephalin peptide. In addition, the glycine2-3 peptide bond is essential for opiate-like activity.     

Quantitative histochemical studies of striatal dopamine depletion following dl-α-methyl-p-tyrosine administration

This study investigated the use of a microfluorimetric histochemical method for the measurement of the depletion of dopamine in the rat caudate nucleus, following α-methyl-p-tyrosine (α-MT) administration. The depletion in three behavioral situations was compared with that of a control group which remained in a cage.The results of the control group indicate that there had been a reduction of approximately 50% in the intensity of the formaldehyde-induced fluorescence derived from dopamine in a region of the neuropil of the caudate nucleus, during the interval (3 hr 40 min) between α-MT, 300 mg/kg i.p., and killing. Disruption of conditioned avoidance response (CAR) performance after α-MT administration was confirmed, but in this study CAR performance in previously trained rats did not have a significant effect on the depletion of formaldehyde-induced fluorescence of the striatal neuropil after α-MT administration. The levels of α-MT-induced depletion of formaldehyde-induced fluorescence in the striatal neuropil following a period of muscular co-ordination/activity and following a period of CAR training were also not significantly different from those shown by a control group.     

Nampt/Visfatin/PBEF研究进展

尼克酰胺磷酸核糖转移酶(nicotinamide phosphoribosyltransferase,Nampt)是生物合成NAD的关键限速酶,又被称为前B细胞克隆增强因子(pre-B cell colony enhancing factor,PBEF)和内脏脂肪素(visfatin).最近研究发现,Nampt/Visfatin/PBEF在NAD生物合成、代谢、炎症反应和细胞增殖、分化、凋亡等诸多领域发挥作用,可能影响2型糖尿病、急性肺损伤、恶性肿瘤等疾病发生、发展和预后.本文主要对Nampt/Visfatin/PBEF的生理功能及临床意义进行综述.