mTOR通路增强宫颈癌紫杉醇耐药细胞株HeLa/PTX对紫杉醇的敏感性

目的探讨mTOR在宫颈癌紫杉醇耐药中的作用及mTORC1/2双重抑制剂OSI-027联用紫杉醇后HeLa/PTX细胞对紫杉醇(paclitaxel,PTX)敏感性的变化并对相关机制进行研究。方法用sh-RNA-Raptor及sh-RNA-Rictor质粒转染HeLa/PTX细胞以下调Rictor及Raptor的表达,采用western blot法检测mTOR信号通路相关蛋白(Raptor、Rictor、p-Akt(ser473)、Akt和p-p70S6K)和凋亡相关蛋白(Bcl-2和Bax)的表达情况;采用平板克隆形成实验、CCK-8法及Western blot法检测单用mTORC1/2双重抑制剂(OSI-027)、PTX及联用OSI-027和PTX后细胞克隆形成能力、增殖活力的变化并计算药物联用指数(combination index,CI)及mTOR信号通路相关蛋白和凋亡相关蛋白的表达情况。结果与对照组相比,在HeLa/PTX细胞中下调Raptor后p-p70S6K表达显著降低(P<0.001),p-Akt(ser473)/Akt比率显著升高(P<0.001),Bcl-2/Bax比值无显著差异(P>0.05)。下调Rictor后p-p70S6K蛋白表达、p-Akt(ser473)/Akt及Bcl-2/Bax比值均显著降低(P<0.001);与单独使用OSI-027或PTX相比,联合用药组细胞的克隆形成能力及增殖活力均明显下降且两药联用具有协同作用;与空白对照组相比,单用PTX处理HeLa/PTX细胞后p-Akt(ser473)/Akt比率略降低(P<0.05),p-p70S6K表达无明显变化(P>0.05),而单用OSI-027处理HeLa/PTX细胞后p-Akt(ser473)/Akt比率及p-p70S6K表达均显著降低(P<0.001);与单用OSI-027及PTX相比,联合用药处理HeLa/PTX细胞后p-Akt(ser473)/Akt比值、Bcl-2/Bax比值及p-p70S6K蛋白表达均显著降低(P<0.001)。结论抑制mTORC2信号通路的活性可减弱mTORC1抑制引起的p-Akt(ser473)反馈激活可成为克服紫杉醇耐药的有效靶点;mTORC1/2双重抑制剂OSI-027与紫杉醇联用可产生协同抗肿瘤作用。     

PTEN/mTOR通路在高糖诱导的人绒毛膜滋养层细胞HTR-8/SVneo凋亡中的作用机制探讨 #br#

目的 探讨高糖诱导人绒毛膜滋养层细胞HTR-8/SVneo凋亡的相关机制。方法 体外培养人绒毛膜滋 养层细胞HTR-8/SVneo,分为空白对照组、高糖组、NC组（阴性对照组）、第10号染色体缺失的磷酸酶及张力蛋白同 源物基因（PTEN）-siRNA 组（抑制 PTEN 表达组）及哺乳动物雷帕霉素靶蛋白（mTOR）通路抑制剂（GDC-0349）组。 四甲基偶氮唑蓝（MTT）法检测HTR-8/SVneo细胞增殖能力;流式细胞仪检测细胞凋亡情况;蛋白免疫印迹法检测凋 亡相关蛋白及PTEN/mTOR通路相关蛋白表达情况。结果 与空白对照组比较,高糖组HTR-8/SVneo细胞增殖抑制 率、凋亡率及Bcl-2相关X蛋白（Bax）、活化的含半胱氨酸的天冬氨酸蛋白水解酶3（cleaved caspase-3）、PTEN蛋白表 达水平均显著升高（P＜0.05）,B淋巴细胞瘤-2（Bcl-2）、磷酸化磷脂酰肌醇-3激酶（p-PI3K）/PI3K、磷酸化蛋白激酶B （p-AKT）/AKT、磷酸化 mTOR（p-mTOR）/mTOR 蛋白表达水平显著降低（P＜0.05）;与高糖组、NC 组比较,PTENsiRNA组HTR-8/SVneo细胞增殖抑制率、凋亡率及Bax、cleaved caspase-3、PTEN蛋白表达水平均显著降低,Bcl-2、pPI3K/PI3K、p-AKT/AKT、p-mTOR/mTOR 蛋白表达水平显著升高（P＜0.05）;与 PTEN-siRNA 组比较,GDC-0349 组 HTR-8/SVneo细胞增殖抑制率、凋亡率及Bax、cleaved caspase-3蛋白表达水平均显著升高,Bcl-2、p-PI3K/PI3K、pAKT/AKT、p-mTOR/mTOR 蛋白表达水平显著降低（P＜0.05）。结论 高糖可抑制人绒毛膜滋养层细胞 HTR-8/ SVneo增殖能力,诱导其凋亡,可能是通过上调PTEN表达、抑制PI3K/AKT/mTOR通路活化实现的。     

磷脂酰肌醇-3磷酸激酶/AKT/雷帕霉素靶蛋白信号通路参与中枢神经损伤保护与修复的研究进展

中枢神经细胞对各种损伤刺激耐受差,损伤后神经修复困难.因此促进神经保护增强神经再生能力已成为神经治疗关键.磷脂酰肌醇-3磷酸激酶/AKT/雷帕霉素靶蛋白(PI3K/AKT/mTOR)信号通路是调节细胞周期的重要通路,在细胞增殖、生长、分化过程中起中心调控作用,在神经损伤过程中通过激活PI3K/AKT/mTOR信号通路可减少神经细胞死亡,促进神经修复.该文对PI3K/AKT/mTOR信号通路在中枢神经损伤保护作用、修复机制及可能风险作一综述,探讨将PI3K/AKT/mTOR信号通路作为靶点治疗中枢神经疾病.     

下调TP53INP1基于PI3K/AKT/mTOR信号通路对宫颈癌细胞凋亡、侵袭、迁移的影响

目的 分析下调肿瘤蛋白P53诱导性核蛋白1(TP53INP1)基于PI3K/AKT/mTOR信号通路对宫颈癌细胞凋亡、侵袭、迁移的影响。方法 按照脂质体2000说明书对细胞进行转染TP53INP1 mimics及TP53INP1 inhibitor,按照实验设计，将其分为对照组及上调组(TP53INP1 inhibitor)、下调组(TP53INP1 mimics)。荧光定量PCR法检测TP53INP1表达量，采用细胞划痕实验法检测细胞迁移能力，采用流式细胞仪检测细胞凋亡能力，采用Transwell小室实验检测细胞侵袭能力，Western blot法检测PI3K/AKT/mTOR通路中PI3K、AKT、mTOR表达量。结果 上调组表达量高于下调组TP53INP1,差异有统计学意义(P<0.05);下调组凋亡率高于上调组，差异有统计学意义(P<0.05);下调组侵袭能力、迁移能力低于上调组，差异有统计学意义(P<0.05);下调组PI3K、AKT、mTORBax蛋白表达量低于上调组，差异有统计学意义(P<0.05)。结论 TP53INP1在宫颈癌中呈现高表达，下调...     

雷公藤红素通过PI3K/AKT/mTOR信号通路对胃癌MFC细胞增殖和凋亡的影响

目的研究雷公藤红素对胃癌MFC细胞内PI3K/AKT/mTOR信号通路的影响及其对胃癌MFC细胞增殖的抑制和促凋亡作用机制。方法分别设置对照组和雷公藤红素低、中、高剂量(5、10、20 mmol/L)组,采用MTT法检测雷公藤红素对胃癌MFC细胞增殖的影响;采用流式细胞技术检测雷公藤红素对胃癌MFC细胞周期的影响及MFC细胞凋亡的情况;Western blotting检测雷公藤红素对胃癌MFC细胞内凋亡相关蛋白Bax、Bcl-2和PI3K、AKT和mTOR蛋白表达的影响;实时定量PCR检测雷公藤红素对胃癌MFC细胞内PI3K、AKT和mTORm RNA表达的影响。结果与对照组比较,雷公藤红素能够呈剂量相关性地显著抑制胃癌MFC细胞的增殖(P0.05);与对照组比较,雷公藤红素能够呈剂量相关性地显著引起MFC细胞G2/M期阻滞(P0.05);与对照组比较,雷公藤红素能够呈剂量相关性地显著促进MFC细胞的凋亡(P0.05);与对照组比较,雷公藤红素能够呈剂量相关性地显著抑制MFC细胞内抗凋亡蛋白Bcl-2蛋白和PI3K、AKT、mTOR蛋白的表达(P0.05),显著促进MFC细胞内促凋亡蛋白Bax的表达(P0.05);与对照组比较,雷公藤红素能够呈剂量相关性地显著抑制MFC细胞内PI3K、AKT和mTORm RNA的表达(P0.05)。结论雷公藤红素能够抑制胃癌MFC细胞的增殖并促进胃癌MFC细胞凋亡,其作用机制可能是通过抑制胃癌MFC细胞内PI3K/AKT/mTOR信号通路中PI3K、AKT、mTOR等蛋白的表达而抑制胃癌MFC细胞的增殖,进而促进胃癌MFC细胞内促凋亡蛋白Bax的表达,同时抑制抗凋亡蛋白Bcl-2的表达,从而促进胃癌MFC细胞凋亡。     

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。     

PI3K/AKT/mTOR信号通路参与脊髓损伤后神经元自噬的研究进展

PI3K/AKT/mTOR信号通路是脊髓损伤后的一条经典的自噬途径,脊髓损伤后导致的神经元细胞凋亡、轴 突脱髓鞘和炎症反应等受 PI3K/AKT/mTOR 信号通路的调控,并和神经元自噬相关。介绍脊髓损伤后 PI3K/AKT/ mTOR信号通路在神经元自噬过程中的主要作用,为进一步研究脊髓损伤提供参考。     

PI3K/mTOR信号通路及双重抑制剂NVP-BEZ235的开发

磷脂酰肌醇3-激酶/蛋白激酶B/雷帕霉素靶蛋白(PI3K/Akt/mTOR)信号通路与肿瘤的发生发展密切相关.PI3K/mTOR双重抑制剂已成为抗肿瘤药物研发的热点之一.近年,NVP-BEZ235因其能有效并特异性地双重抑制PI3K/mTOR信号通路的异常活化而受到关注.本文综述PI3K/Akt/mTOR信号通路及NVP-BEZ235的开发.     

Z-没药甾酮通过激活PI3K/AKT/eNOS通路发挥脑微血管内皮细胞保护作用

摘要：目的:探讨Z-没药甾酮（Z-GS）对大鼠脑微血管内皮细胞的保护作用及药理机制。方法:脑微血管内皮细胞制作氧糖剥夺模型体外模拟缺血性脑卒中,培养的脑微血管内皮细胞分为对照组、模型组、 Z-GS低、中、高(12.5,25,50μmol·L-1)剂量组。给药组细胞在OGD造模前分别给予不同剂量的Z-GS处理。在机制研究中,50μmol·L-1?Z-GS+抑制剂组在造模给药前加入PI3K抑制剂LY294002。试剂盒检测细胞活力、乳酸脱氢酶（LDH）释放和血管活性物质水平;免疫印迹分析磷脂酰肌醇3-激酶（PI3K）、蛋白激酶B（AKT）和内皮型一氧化氮合酶（eNOS）蛋白表达及磷酸化水平;LY294002用于特异性抑制PI3K表达。结果:Z-GS给药可提高细胞活力、降低LDH释放。同时Z-GS可通过降低内皮素-1和血栓素B2水平、升高血栓调节蛋白和6-酮-前列环素1α水平缓解血瘀。机制研究表明,Z-GS给药可激活PI3K/AKT/eNOS通路,增加一氧化氮（NO）的生成。而在LY294002特异性抑制PI3K后,Z-GS对该通路的调控作用消失。结论:Z-GS可通过调控血管活性物质发挥血管内皮保护作用,其机制与激活PI3K/AKT/eNOS通路,进而促进NO的生成有关。     

基于mTOR通路的大黄素对肾小管上皮细胞转分化的干预作用机制研究

目的：观察大黄素（EMO）对高糖诱导的人肾小管上皮细胞（HK-2）转分化（EMT）的干预效应及对mTOR信号通路的影响,探讨大黄素防治糖尿病肾病（diabetic nephropathy,DN）的可能作用机制。方法：将体外培养的人肾小管上皮细胞HK-2分为正常组（NG组,5.56 mmol·L^-1葡萄糖）、高糖组（HG组,60 mmol·L^-1葡萄糖）、大黄素组（EMO组,60 mmol·L^-1葡萄糖+10 μmol·L^-1大黄素）,在用MTT证实大黄素对正常培养的HK-2细胞无毒性的基础上,选择一个有效的药物浓度,以mTOR特异性抑制剂雷帕霉素（20 nmol·L^-1）作为对照。各组细胞培养72 h时后,倒置显微镜观察HK-2细胞形态。Western blot法检测细胞中mTOR、P70S6K、4-EBP1蛋白磷酸化水平;免疫荧光法检测α-SMA以及E-cadherin蛋白分布及表达。结果：高糖可以诱导HK-2细胞形态由多边鹅卵石样发生纤维化样改变,激活mTOR、P70S6K、4-EBP1蛋白磷酸化,降低细胞中上皮表型蛋白E-cadherin的表达,并增加间质表型蛋白α-SMA的表达。大黄素可以改善高糖导致的HK-2细胞形态的变化,降低mTOR、P70S6K、4-EBP1蛋白磷酸化水平,E-cadherin表达的减少及α-SMA表达的增加,雷帕霉素也能达到与大黄素相同的效果。结论：大黄素可以改善高糖诱导的HK-2细胞上皮-间质转分化,此效应可能与抑制mTOR信号通路有关。     

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.