茶多酚对谷氨酸脱氢酶和纳豆氨含量的影响

纳豆中含有纳豆激酶等功能性成分,能够有效预防心血管疾病,然而,发酵过程中产生的氨味大大降低了其在我国的可接受度。为降低纳豆氨含量,本研究比较4种物质对纳豆芽孢杆菌产氨的关键酶——谷氨酸脱氢酶的抑制效果,结果显示茶多酚作用效果最佳。研究表明茶多酚是一种底物竞争型抑制剂,IC50为20.60 μg/mL,且它能够进入纳豆芽孢杆菌细胞,有望作为添加剂来抑制后者胞内的谷氨酸脱氢酶活性,减少纳豆发酵过程中氨的产生。通过分析纳豆芽孢杆菌的生长规律、纳豆发酵过程中氨含量的变化趋势及茶多酚抑制产氨的效果,确定最佳工艺条件为:在发酵第11小时添加4.16 mg/g茶多酚。该条件下,纳豆中氨含量下降了63.90%,而纳豆激酶活性没有显著性变化。经感官评定证实,添加茶多酚能够有效降低纳豆的氨味,提高产品的可接受度,具有极大的应用价值。     

基于基因组挖掘技术的新型谷氨酸脱羧酶基因挖掘及表达鉴定

采用基因组挖掘技术,以来源于Lactobacillus brevis活性较高的谷氨酸脱羧酶(glutamate decarboxylase,GAD)LbGAD为探针,从乳酸菌(Lactococcus lactis、Lactobacillus senmaizukei)和肠球菌(Enterococcus sulfureus...     

肉豆蔻木酚素通过PI3K/Akt信号通路调节HT22细胞自噬和凋亡的作用机制

为探究天然成分肉豆蔻木酚素对海马神经元凋亡与自噬的调控机制;利用谷氨酸诱导HT22细胞制备氧化应激细胞模型;研究肉豆蔻木酚素对HT22细胞存活率的影响。通过苏木精-伊红（hematoxylin-eosin;HE）染色、脱氧核糖核苷酸末端转移酶介导的缺口末端标记法（terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling;TUNEL）染色和流式细胞术评估细胞形态变化与凋亡情况;通过分子对接技术分析肉豆蔻木酚素与磷酸肌醇3-激酶（phosphatidylinositide 3-kinase;PI3K）结合情况;采用免疫印迹法分析肉豆蔻木酚素和PI3K抑制剂LY294002或自噬抑制剂3-甲基腺嘌呤（3-methyladenine;3-MA）对PI3K、蛋白激酶B（protein kinase B;Akt）的蛋白表达水平变化的影响以及凋亡与自噬相关蛋白活化半胱胺酸蛋白酶-3（Cleaved caspase-3）、微管相关蛋白轻链3β（microtubule associated protein light chain 3 beta;LC3B）、自噬相关基因5（autophagy related gene 5;Atg5）等相关蛋白表达的影响。结果显示;与氧化应激细胞模型相比;肉豆蔻木酚素可显著增强HT22细胞活性、减少凋亡细胞数量;且呈剂量依赖性;其能增强p-PI3K和p-Akt磷酸化、抑制Cleaved caspase-3表达;通过PI3K/Akt通路发挥抗凋亡作用;降低Atg5和LC3B表达、增加p62水平;有抑制自噬的作用。LY294002可阻断肉豆蔻木酚素促进PI3K和Akt磷酸化的作用;3-MA可增强其神经保护效果。综上;肉豆蔻木酚素通过促进PI3K/Akt信号通路激活、调控自噬抑制、减少谷氨酸诱导的HT22细胞凋亡从而发挥神经保护作用。     

芝麻素对阿尔茨海默病大鼠学习记忆及海马谷氨酸表达的影响

目的: 研究芝麻素（sesamin,Ses）对阿尔茨海默病(Alzheimer's disease,AD)大鼠学习记忆及海马谷氨酸(Glu)表达的影响。方法: 选用正常SD大鼠40只,首先建立空白对照组（NS 5.0 mL·kg^-1·d^-1）10只,其余灌胃三氯化铝（AlCl3,15 mg·kg^-1·d^-1)联合腹腔注射D-半乳糖（D-gal,180 mg·kg^-1·d^-1）造模20周。于造模第13周将大鼠随机分为AD模型组（NS 5.0 mL·kg^-1·d^-1）,Ses低剂量组（80 mg·kg^-1·d^-1）,Ses高剂量组（160 mg·kg^-1·d^-1）,每组各10只,继续给药8周后,Morris水迷宫法检测其学习记忆能力;免疫组化法检测大鼠海马Glu阳性细胞的表达;Western Blot法检测大鼠海马Glu蛋白表达。结果: Ses用药组可以明显缩短AD大鼠逃避潜伏期,增加穿越平台次数,改善其学习记忆能力,同时可以下调Glu阳性细胞和蛋白表达。结论: Ses可能通过拮抗Glu受体,有效减少Glu水平,降低了神经兴奋性毒性,从而改善AD大鼠的学习记忆能力。     

谷氨酸钠对缺铁大鼠铁代谢的影响

试验选用大鼠作为模型,研究谷氨酸钠对大鼠的铁代谢指标的影响。试验大鼠30只分为3个试验组:对照组、FeSO_4组和FeSO_4-谷氨酸钠试验组(日粮中添加1%味精)。试验结果显示:1)日粮中添加味精的缺铁大鼠补铁后,大鼠体重有所增加(P0.05)。2)日粮中添加味精的缺铁大鼠灌胃补铁后,贫血大鼠血清铁和铁蛋白均恢复到正常水平,和对照组相比显著增高(P0.05);和FeSO_4相比,FeSO_4-味精组血红蛋白含量增加了3.97%(P0.05)。结果显示味精不但不影响动物对铁的吸收,还有一定的促进铁吸收作用。     

表达谷氨酸脱羧酶重组枯草芽孢杆菌的构建及其发酵条件的优化

谷氨酸脱羧酶（GAD）是生物合成γ-氨基丁酸（GABA）的关键酶,本研究通过基因工程构建了一株产GAD的重组枯草芽孢杆菌,并对其产GAD的发酵条件进行优化。分别通过单因素法、正交实验、极差分析和响应面法确定了最佳培养基成分（g/L）及发酵条件为:蔗糖23.5,豆粕10、乙酸铵为8.5、磷酸二氢钾4.1、七水硫酸镁0.5,p H7.0,培养温度37℃。在优化条件下GAD酶活达到0.413 U/m L,与优化前的GAD酶活0.143 U/m L相比,酶活提高了188.8%。本研究有助于后续开发枯草杆菌生产γ-氨基丁酸的工艺,以克服现在γ-氨基丁酸生产工艺中,大肠杆菌安全性的问题和乳酸菌成本过高的问题。      

Involvement of Glutamate Transporter-1 in Neuroprotection against Global Brain Ischemia-Reperfusion Injury Induced by Postconditioning in Rats

Ischemic postconditioning refers to several transient reperfusion and ischemia cycles after an ischemic event and before a long duration of reperfusion. The procedure produces neuroprotective effects. The mechanisms underlying these neuroprotective effects are poorly understood. In this study, we found that most neurons in the CA1 region died after 10 minutes of ischemia and is followed by 72 hours of reperfusion. However, brain ischemic postconditioning (six cycles of 10 s/10 s reperfusion/re-occlusion) significantly reduced neuronal death. Significant up-regulation of Glutamate transporter-1 was found after 3, 6, 24, 72 hours of reperfusion. The present study showed that ischemic postconditioning decreases cell death and that upregulation of GLT-1 expression may play an important role on this effect.     

Pre-Ischemic Treadmill Training for Prevention of Ischemic Brain Injury via Regulation of Glutamate and Its Transporter GLT-1

Pre-ischemic treadmill training exerts cerebral protection in the prevention of cerebral ischemia by alleviating neurotoxicity induced by excessive glutamate release following ischemic stroke. However, the underlying mechanism of this process remains unclear. Cerebral ischemia-reperfusion injury was observed in a rat model after 2 weeks of pre-ischemic treadmill training. Cerebrospinal fluid was collected using the microdialysis sampling method, and the concentration of glutamate was determined every 40 min from the beginning of ischemia to 4 h after reperfusion with high-performance liquid chromatography (HPLC)-fluorescence detection. At 3, 12, 24, and 48 h after ischemia, the expression of the glutamate transporter-1 (GLT-1) protein in brain tissues was determined by Western blot respectively. The effect of pre-ischemic treadmill training on glutamate concentration and GLT-1 expression after cerebral ischemia in rats along with changes in neurobehavioral score and cerebral infarct volume after 24 h ischemia yields critical information necessary to understand the protection mechanism exhibited by pre-ischemic treadmill training. The results demonstrated that pre-ischemic treadmill training up-regulates GLT-1 expression, decreases extracellular glutamate concentration, reduces cerebral infarct volume, and improves neurobehavioral score. Pre-ischemic treadmill training is likely to induce neuroprotection after cerebral ischemia by regulating GLT-1 expression, which results in re-uptake of excessive glutamate.     

Mating activates NMDA receptors in the medial preoptic area of male rats.

Studies have emphasized the role of the medial preoptic area (MPOA) as an important site for the regulation of male sexual behavior. Indeed, ablations of the MPOA impair sexual behavior, whereas stimulation of the MPOA enhances behavior. Furthermore, neural activity in the MPOA increases with mating. The current study tested the hypothesis that activation of N-methyl-D-aspartate (NMDA) receptors occurs in MPOA neurons and is essential for the expression of male sexual behavior in rats. Results indicate that nearly all MPOA neurons that expressed Fos following mating also contained the NR1 subunit of NMDA receptors. Furthermore, mating increased phosphorylation, thus activation, of NR1 in the MPOA. Additionally, blocking NMDA receptors significantly decreased mating-induced Fos expression and mating-induced phosphorylation of NMDA receptors and impaired male sexual behavior. These results provide evidence that mating activates NMDA receptors in the MPOA and that this activation is important for the expression of male sexual behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

麦胚富集γ-氨基丁酸的培养条件优化

采用水浴保温的方法对麦胚中γ-氨基丁酸（GABA）进行富集,研究了培养温度、时间、液料比和培养液pH对麦胚中GABA含量和谷氨酸脱羧酶（GAD）活性的影响,采用响应面法对麦胚富集GABA的培养条件进行了优化。结果表明,在一定范围内培养温度、时间、液料比和培养液pH可有效提高麦胚中GAD活性,促进GABA积累。Box-Behnken实验结果显示,麦胚富集GABA的最优培养条件为培养温度46℃,时间1.5h,液料比6∶1（mL/g）,培养液pH4.6。在此培养条件下,麦胚中GABA最大富集量为36.78mg/g,是麦胚原料的5.51倍。方差分析表明,所建的回归模型能够很好的预测麦胚中GABA富集量的变化。