The anorexic effect of Ex4/Fc through GLP-1 receptor activation in high-fat diet fed mice

Exendin-4 （Ex4）, a peptide initially found in the saliva of the Gila monster, can activate the signaling pathway of the incre- tin hormone glucagon-like peptide-1 （GLP-1） through the GLP-1 receptor （GLP-1R）. We previously reported that a chimera protein consisting of Ex4 and mouse IgG heavy chain constant regions （Ex4/Fc） can exert biological effects of GLP-1, such as improving glycemic control and ameliorating manifestations in diabetic mice. The aim of this study was to determine whether Ex4/Fc is effective in modulating energy homeostasis in mice. Our results showed that in vivo expres- sion of Ex4/Fc by intramuscular injection of the plasmid en- coding Ex4/Fc followed by local electroporation effectively decreased food intake in the mice on high-fat diet （HFD） feeding. In addition, the reduced energy intake was associated with the decreased excrements from the Ex4/Fc-treated HFD mice but not the Fc control mice. Remarkably, the Ex4/Fc- treated HFD mice displayed significantly lower triglyceride （TG） levels when compared with the control mice. Interest- ingly, while the leptin levels were not changed, the circulating ghrelin levels were higher in Ex4/Fc mice than those in the Fc control mice. These results suggested that Ex4/Fc can improve energy metabolism and lipid metabolism through GLP-1R in mice under excessive nutrition conditions.     

ifirmed Diagnosis by RT-PCR and Phylogenetic Analysis of Peste des Petits Ruminants Viruses in Tibet,China

This paper reports the confirmed diagnosis by nested RT-PCR of PPR cases in Tibet, China in 2007, and results of phylogenetic analysis. Results showed that the 11 tested samples were PPRV positive by nested RT-PCR, of which 2 samples were genetically close to the X7443 strain （Nigeria 75/1） of lineage I, and 3 samples close to the strain AY560591 （Sungri96） of linage IV with 96.6%, 97.3%, 97.6% and 98% nucleotide sequence homogeneity respectively, based on partial sequencing of the F gene from 5 samples and complete sequencing of the N/M/F/H genes from one sample. This study suggested that there are at least 2 origins of PPRV in China.     

Expression of acid-sensing ion channels in nucleus pulposus cells of the human intervertebral disk is regulated by non-steroid anti-inflammatory drugs

Non-steroid anti-inflammatory drugs （NSAIDs） are general- ly used in the treatment of inflammation and pain through cyclooxygenase （COX） inhibition. Mounting evidence has indicated additional COX-independent targets for NSAIDs including acid-sensing ion channels （ASICs） la and 3. However, detailed function and mechanism of ASICs still remain largely elusive. In this study, the impact of NSAIDs on ASICs in nucleus puiposus cells of the human interverte- bral disk was investigated. Nucleus pulposus cells were iso- lated and cultured from protruded disk tissues of 40 patients. It was shown that ASICla and ASIC3 were expressed and functional in these cells by analyzing proton- gated currents after ASIC inhibition. We further investi- gated the neuroprotective capacity of ibuprofen （a COX in- hibitor）, psaimotoxin-1 （PcTX1, a tarantula toxin specific for homomeric ASICla）, and amiloride （a classic inhibitor of the epithelial sodium channel ENaC/DEG family to which ASICs belong）. PcTXl-containing venom has been shown to be comparable with amiloride in its neuroprotective features in rodent models of ischemia. Taken together, our data showed that amiloride, PcTX1, and ibuprofen decreased ASIC protein expression and thereby exerted protective effects from ASIC inhibition-mediated cell damage.     

Anterograde and Retrograde Regulation of Nuclear Genes Encoding Mitochondrial Proteins during Growth,Development, and Stress

Mitochondrial biogenesis and function in plants require the expression of over 1000 nuclear genes encoding mitochondrial proteins （NGEMPs）. The expression of these genes is regulated by tissue-specific, developmental, internal, and external stimuli that result in a dynamic organelle involved in both metabolic and a variety of signaling processes. Although the metabolic and biosynthetic machinery of mitochondria is relatively well understood, the factors that regu- late these processes and the various signaling pathways involved are only beginning to be identified at a molecular level. The molecular components of anterograde （nuclear to mitochondrial） and retrograde （mitochondrial to nuclear） signaling pathways that regulate the expression of NGEMPs interact with chloroplast-, growth-, and stress-signaling pathways in the cell at a variety of levels, with common components involved in transmission and execution of these signals. This positions mitochondria as important hubs for signaling in the cell, not only in direct signaling of mitochondrial function per se, but also in sensing and/or integrating a variety of other internal and external signals. This integrates and optimizes growth with energy metabolism and stress responses, which is required in both photosynthetic and non-photosynthetic cells.     

Pyrrolidine dithiocarbamate protects pancreatic β-cells from oxidative damage through regulation of FoxO1 activity in type 2 diabetes rats

Pyrrolidine dithiocarbamate （PDTC） can lower the bloot glucose level and improve the insulin sensitivity in diabeti, rats. However, the mechanisms underlying this effect o PDTC treatment in diabetic rats remained uncertain, h this study, we evaluated the mechanisms by which PDT（ conferred protection against oxidative damage to pancreat ic islet β-cells in rats with experimental type 2 diabete mellitus （DM）. DM in the rats was elicited by long-tern high-fat diet accompanied with a single intraperitonea （i.p.） injection of a low dose of streptozotocin. After a 7-da1 administration of PDTC （50 mg/kg/day i.p.）, blood glucos levels were measured and pancreatic tissues were collecte / for the determination of various biochemical and enzyma 1 ic activities using immunohistochemistry, immunofluoresI cence, and western blot techniques. The percentage o 1 apoptotic pancreatic islet β-cells was detected by flow cyto metry. The results showed that diabetic rats had elevate blood glucose levels and insulin resistance, accompanieq with an increase in malondialdehyde content, nitrotyrosin production, and inducible nitric oxide synthase expression A decrease in superoxide dismutase and glutathione pero idase activities was also observed in DM rats, culminatin with elevated β-cell apoptosis. PDTC treatment significantl reduced the oxidative damage and the β-cell apoptosi and also increased the insulin production through down-reg lating FoxO1 acetylation and up-regulating nuclear PDX- level. These data suggested that PDTC can protect islet βcells from oxidative damage and improve insulin productio through regulation of PDX-1 and FoxO1 in a DM rat model.     

Comparison of two in vitro angiogenesis assays for evaluating the effects of netrin-1 on tube formation

Netrin-1 is a neural guidance cue that also regulates vascu- lar development. Controversial results, however, have been obtained concerning the roles of netrin-1 in vascular devel- opment both in vivo and in vitro. In the present study, two in vitro angiogenesis assays were compared to evaluate the effects of netrin-1 secreted by retrovirally transduced mel- anoma cells （Mel2a-netrinl） on tube formation. The results showed that there was no obvious difference in tube forma- tion induced by conditioned media （CM） from the control, Mel2a-netrinl and Mel2a cells in a matrigel assay. The results of another in vitro assay, in which endothelial cells were co-cultured with human fibroblasts, however, showed that Mel2a-netrinl CM inhibited the tube formation, sup- posedly through blocking the elongation and coalescence of human umbilical vein endothelial cells （HUVECs）. These results confirmed that the matrigel assay is not able to demonstrate the anti-angiogenic roles of netrin-1.     

失血性休克大鼠淋巴管及血管压力对去甲肾上腺素反应的相关性研究

目的:观察失血性休克(HS)大鼠淋巴管与血管对去甲肾上腺素(NE)反应性的变化,探讨淋巴管与血管反应性的关系。方法:大鼠行左侧腹部手术,分离胸导管,测量淋巴管压力(LP);股部手术,经股动脉测量平均动脉血压(MAP)。休克组经股动脉放血复制HS模型(维持MAP40mmHg左右,3h),假手术(sham)组仅手术。在休克不同时间点(或相当),股静脉注射NE(5μg/kg.bw),观察给予NE前后两组大鼠LP以及MAP的变化。结果:休克即刻淋巴管对NE的反应性与sham组无明显差异,到休克0.5h时淋巴管对NE的升压反应开始减弱,至休克3h依然维持低反应性;与sham组相比,休克组血管对NE反应性呈双相表现,休克即刻血管高反应性,休克1h后对NE的升压作用开始减弱,表现为血管低反应性;休克后二者的反应性相关。结论:大鼠HS后淋巴管出现低反应性,且出现在血管低反应性之前;休克发展进程中淋巴管与血管对NE的低反应性呈正相关。     

脱氢表雄酮对大鼠脂类代谢和抗氧化作用的影响

目的：研究灌胃脱氢表雄酮（DHEA）对大鼠脂类代谢和抗氧化作用的影响。方法：选用健康雄性SD大鼠40只,随机分为4组（n=10）。对照组灌胃给予灭菌生理盐水,实验组灌胃给予20mg／kg、10mg／kg、5mg／kg体重的DHEA受试溶液,灌胃量均为1．5ml。每天一次,连续35d。实验结束后采血测定血糖（BG）、甘油三酯（TG）、总胆固醇（TO）、高密度脂蛋白胆固醇（HDL-C）、低密度脂蛋白胆固醇（LDL-C）,血清和肝脏超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量。结果：DHEA显著降低大鼠血糖、TG、HDL-c及血清和肝脏MDA含量,显著升高血清LDL-c含量和肝脏SOD活性,而对大鼠体重、血清TC含量和SOD活性没有显著影响。结论：DHEA具有降低大鼠血脂和增强抗氧化能力的作用。     

下坡跑后大鼠腓肠肌成肌调节因子的变化

目的:探讨成肌调节因子(MyoD)在肌肉损伤修复过程中的动态表达,为促进运动肌肉损伤的再生修复提供实验依据。方法:将健康雄性2月龄SD大鼠80只,随机分为对照组(n=10)和下坡运动组(n=70),下坡运动组再分为运动后即刻组、12h、24h、48h、72h、7d和14d组,各运动组动物均进行持续性下坡跑,分别在运动结束后8个时间点麻醉,下腔静脉取血,分离血清,取双侧腓肠肌。常规检测CK、LDH的活性。采用免疫组织化学染色法以及计算机图像分析技术定量统计MyoD因子表达情况。结果:血清CK、LDH在运动后即刻显著上升,后逐渐下降至正常水平。成肌调节因子MyoD在正常骨骼肌中即有表达,各运动组大鼠腓肠肌MyoD因子表达较对照组均有增加,48h组大鼠腓肠肌MyoD免疫阳性细胞核数明显多于对照组(P0.05),后随时间逐渐下降。结论:离心运动后即刻MyoD的表达水平开始上升,48h达到峰值,随后逐渐下降至正常水平。提示成年早期大鼠(2月龄)已具备较成熟的肌肉再生修复能力。     

Hyperhomocysteinemia stimulates hepatic glucose output and PEPCK expression

Homocysteine is an intermediate in the sulfur amino acid metabolism. Recent studies suggested that there might be links between hyperhomocysteinemia and insulin resistance. In the present study, we investigated the effect of homocysteine on glucose metabolism. We demonstrated that the levels of insulin were significantly higher in mice with hyperhomocysteinemia than those in the normal mice after administration of glucose. The effect of insulin on glucose output was significantly blocked in the homocysteine-treated hepatocytes. In addition, the expression of phosphoenolpyruvate carboxykinase （PEPCK） gene was elevated in the liver of mice with hyperhomocysteinemia and primary mouse hepatocytes treated with homocysteine. The action of homocysteine was suppressed by H89, a protein kinase A （PKA） inhibitor. Thus, hyperhomocysteinemia may be considered as a risk factor that contributes to the development of insulin resistance with respect to elev- ated glucose output and upregulation of PEPCK, probably via the PKA pathway. Our study provides a novel mechanistic explanation for the development of insulin resistance in hyperhomocysteinemia.     

Role of chaperone-mediated autophagy in degrading Huntington＇s disease-associated huntingtin protein

Mutant N-terminal huntingtin （Htt） protein resulting from Huntington＇s disease （HD） with expanded polyglutamine accumulates and forms aggregates in vulnerable neurons. Both ubiquitin proteasomai and autophagic pathways con- tribute to the degradation of mutant Htt. Here, we focus on the involvement of chaperone-mediated autophagy （CMA）, a selective form of autophagy in the clearance of Htt. Selective catabolism in CMA is conferred by the presence of a KFERQ-Iike targeting motif in the substrates, by which molecular chaperones recognize the hydrophobic surfaces of the misfolded substrates, and transfer them to the lysosomal membrane protein type-2A, LAMP-2A. The substrates are taken into the lysosomes through LAMP-2A and are rapidly degraded by the lysosomal enzymes. Taken together, we summarize the recent evidence to elucidate that Htt is also a potential substrate of CMA. We propose that the manipulation of CMA could be a therapeutic strat- egy for HD.     

FGF21 treatment ameliorates alcoholic fatty liver through activation of AMPK-SIRT1 pathway

Fibroblast growth factor 21 （FGF21）, a recently identified member of the FGF superfamily, is mainly secreted from the liver and adipose tissues and plays an important role in improving metabolic syndrome and homeostasis. The aim of this study is to evaluate the role of FGF21 in alcoholic fatty liver disease （AFLD） and to determine if it has a therapeutic effect on AFLD. In this paper, we tested the effect of FGF21 on alcohol-induced liver injury in a murine model of chronic ethanol gavage and alcohol-treated HepG2 cells. Male KM mice received single dose of 5 g/kg ethanol gavage every day for 6 weeks, which induced sig- nificant fatty liver and liver injury. The alcohol-induced fatty liver cell model was achieved by adding ethanol into the medium of HepG2 cell cultures at a final concentration of 75 mM for 9 days. Results showed that treatment with recombinant FGF21 ameliorated alcoholic fatty liver and liver injury both in a murine model of chronic ethanol gavage and alcohol-treated HepG2 cells. In addition, FGF21 treatment down-regulated the hepatic expression of fatty acid synthetic key enzyme, activated hepatic AMPK- SIRT1 pathway and significantly down-regulated hepatic oxidative stress protein. Taken together, FGF21 corrects multiple metabolic parameters of AFLD in vitro and in vivo by activation of the AMPK-SIRT1 pathway.     

Drought-Stimulated Activity of Plasma Membrane Nicotinamide Adenine Dinucleotide Phosphate Oxidase and Its Catalytic Properties in Rice

The activity of plasma membrane （PM） nicotinamide adenine dinucleotide phosphate （NADPH） oxidase and its catalytic properties in rice was investigated under drought stress conditions. Drought stress led to decreased leaf relative water content （RWC） and, as a result of drought-induced oxidative stress, the activities of antioxidant enzymes increased significantly. More interestingly, the intensity of applied water stress was correlated with increased production of H2O2 and O2^- and elevated activity of PM NADPH oxidase, a key enzyme of reactive oxygen species generation in plants. Histochemical analyses also revealed increased H2O2 and O2^- production in drought-stressed leaves. Application of diphenylene iodonium （DPI）, an inhibitor of PM NADPH oxidase, did not alleviate drought-induced production of H2O2 and O2^-. Catalysis experiments indicated that the rice PM NADPH oxidase was partially fiavin-dependent. The pH and temperature optima for this enzyme were 9.8 and 40 ℃, respectively. In addition, drought stress enhanced the activity under alkaline pH and high temperature conditions. These results suggest that a complex regulatory mechanism, associated with the NADPH oxidase-H2O2 system, is involved in the response of rice to drought stress.