G蛋白在快速老化痴呆小鼠SAMP8脑组织中的异常表达

摘要 目的：探索在不同月龄小鼠SAMP8皮层和海马中G蛋白的异常表达情况。方法：以正常老化小鼠SAMR1为对照,利用Western-blot方法检测Gαq/11、Gαi和GαS蛋白在8月龄和18月龄小鼠SAMP8的异常表达。结果：与同月龄SAMR1相比,GαS、Gαi和Gαq蛋白在8月龄小鼠SAMP8皮层和海马组织中的表达无明显异常（p﹥0.05）,而到18月龄时,SAMP8皮层部位Gαq表达量明显低于SAMR1（p﹤0.05）,海马部位Gαq和 Gαi的表达量也明显低于SAMR1（p﹤0.05）。结论：18月龄SAMP8脑组织中Gαq和 Gαi的异常表达参与了阿尔海默病（Alzheimer’s, AD）的病理进展,并有望作为AD治疗的一个靶点。     

姜黄素对痴呆模型小鼠学习记忆能力的改善作用及对细胞凋亡的影响

目的探讨姜黄素对痴呆模型小鼠学习记忆能力的改善作用和对脑细胞凋亡及凋亡相关蛋白的影响。方法选用自然快速脑老化小鼠为研究对象,随机将SAMP8脑老化小鼠分为模型组、姜黄素治疗组和盐酸多奈哌齐对照组,将SAMR1小鼠作为正常对照组。采用行为学方法评价各组小鼠治疗前后的学习记忆能力变化,TUNEL法检测海马与皮层的细胞凋亡率,免疫细胞化学法测定细胞凋亡相关蛋白bcl-2和bax的表达情况。结果姜黄素能够明显改善自然快速脑老化小鼠的学习记忆能力,与模型组比较差异有统计学意义(P<0.05);姜黄素治疗组小鼠海马和皮层的细胞凋亡数减少,与模型组比较差异有统计学意义(P<0.05);凋亡相关蛋白bcl-2表达升高,bax表达降低,并且bcl-2/bax比值升高,差异具有统计学意义(P<0.05)。结论姜黄素对痴呆模型小鼠的学习记忆能力具有一定的改善作用,其作用机制可能与其调节凋亡相关蛋白bcl-2与bax的表达有关。     

不同浓度葡萄糖对小鼠海马神经元细胞系HT-22细胞凋亡的影响

目的 探讨不同浓度葡萄糖对小鼠海马神经元细胞系 HT-22细胞凋亡的作用及机制。方法 体外培养小鼠海马神经元 HT-22细胞,使用不同浓度的高糖培养液（25、35、45、55、65、75 mmol/L）分别作用细胞 24、48、72 h,以 25 mmol/L 糖浓度为对照组,其余组为实验组。采用 CCK-8 法检测各组细胞活力变化,筛选出最佳作用时间。HT-22细胞经不同浓度葡萄糖作用 48 h后,微板法检测细胞培养上清液中乳酸脱氢酶（LDH）释放率;光学显微镜观察细胞形态变化;流式细胞术检测各组细胞凋亡情况;蛋白免疫印迹法（Western blot）检测 Bcl-2、Bax蛋白表达量的变化。结果 CCK-8结果显示,高糖可抑制 HT-22细胞的活力,其抑制作用具有剂量和时间依赖性。高糖作用时间48 h时,细胞活力≥80%,可满足后续实验要求。随着葡萄糖浓度的增高,出现细胞数目减少,胞体变大,部分胞核溶解,突触断裂等改变,并且 LDH释放率及凋亡率也明显增高（P＜0.05）,Western blot结果显示凋亡蛋白 Bcl-2表达下降（P＜0.05）,Bax表达增高（P＜0.05）。结论 高糖能显著抑制 HT-22细胞生长和活力,诱导细胞凋亡,其作用机制可能与 Bcl-2、Bax表达有关。     

水通道蛋白-8对结肠癌细胞凋亡及凋亡抑制蛋白的影响

目的：通过表达水通道蛋白-8（AQP-8）真核表达载体,观察水通道蛋白AQP-8对HT-29细胞凋亡及凋亡抑制蛋白（ IAPs）表达的影响。方法取对数生长期的人结肠癌HT-29细胞株用于实验。构建AQP-8真核表达载体并转染HT-29细胞,通过Western blot检测GFP-AQP-8转染效率;采用MTT法检测各组细胞增殖抑制率;流式细胞术检测细胞凋亡率;通过Real Time-PCR和Western blot检测转染GFP-AQP-8的HT-29细胞凋亡抑制蛋白（ IAPs）家族成员c-IAP1、c-IAP2、XIAP、NIAP、Survivin和Livin表达水平。结果 Western blot结果显示,GFP-AQP-8转染后结肠癌HT-29细胞AQP-8基因表达显著上调（ P ＜0{．05）。 MTT分析结果显示,转染了GFP-AQP-8的结肠癌HT-29细胞增殖抑制率显著增加（ P ＜0．05）;流式细胞分析发现,转染了GFP-AQP-8的HT-29细胞凋亡率显著增加（ P ＜0．05）。Real Time-PCR和Western blot结果显示,与转染GFP-N1的阴性对照组相比较,转染了GFP-AQP-8的HT-29细胞c-IAP1、c-IAP1、XIAP、Livin和Survivin的mRNA和蛋白表达水平下降（ P ＜0．05）,NIAP表达变化不明显（ P ＜0．05）。结论过表达AQP-8可抑制HT-29细胞生长,并能通过下调c-IAP1、c-IAP1、XIAP、Livin和Survivin表达诱导HT-29细胞凋亡。     

TFAR19蛋白协同米非司酮对前列腺癌PC-3M细胞凋亡的影响

目的初步探讨TFAR19协同米非司酮(MIF)对前列腺癌PC-3M细胞凋亡的影响。方法构建TFAR19真核表达载体,用脂质体介导的方法转染PC-3M细胞。MTT法检测5、10、20、50和100μmol·L-1MIF作用于前列腺癌PC-3M细胞24~96h的吸光度(A)值。在转染TFAR19的细胞中加入20mol·L-1MIF培养24、48h,MTT比色法检测细胞增殖,原位末端标记(TUNEL)法检测细胞凋亡率,透射电镜进一步观察细胞超微结构的改变。结果构建了PCI-neo-TFAR19真核表达载体并在转染的PC-3M细胞中得到了瞬时表达。MTT实验表明,与对照组相比,5、10μmol·L-1MIF组的A值差异无统计学意义(P>0.05),20、50和100μmol·L-1MIF组的A值差异有统计学意义(P<0.01),MIF对前列腺癌PC-3M细胞的抑制作用呈时间、剂量依赖性;转染PCI-neo-TFAR19并加入20 mol·L-1MIF后,与对照组及单独应用MIF组相比,细胞生长明显受到抑制(P<0.01),细胞凋亡率明显增加(P<0.01),透射电镜观察到典型的细胞凋亡特征(细胞体积缩小,核皱缩、碎裂,染色质呈块状边集等)。结论TFAR19蛋白能够协同米非司酮促进前列腺癌PC-3M细胞凋亡,有望成为前列腺癌的辅助治疗药物。     

TFARl9蛋白协同米非司酮对前列腺癌PC-3M细胞凋亡的影响

目的初步探讨TFARl9协同米非司酮（MIF）对前列腺癌PC-3M细胞凋亡的影响。方法构建TFARl9真核表达载体，用脂质体介导的方法转染PC-3M细胞。MTT法检测5、10、20、50和100μmol&#183;L^-1 MIF作用于前列腺癌PC-3M细胞24～96h的吸光度（A）值。在转染TFARl9的细胞中加入20mol&#183;L^-1 MIF培养24、48h，MTT比色法检测细胞增殖，原位末端标记（TUNEL）法检测细胞凋亡率，透射电镜进一步观察细胞超微结构的改变。结果构建了PCI-neo-TFARl9真核表达载体并在转染的PC-3M细胞中得到了瞬时表达。MTT实验表明，与对照组相比，5、10μmol&#183;L^-1 MIF组的A值差异无统计学意义（P〉0．05），20、50和100μmol&#183;L^-1MIF组的A值差异有统计学意义（P〈0．01），MIF对前列腺癌PC-3M细胞的抑制作用呈时间、剂量依赖性；转染PCI-neo-TFARl9并加入20mol&#183;L^-1 MIF后，与对照组及单独应用MIF组相比，细胞生长明显受到抑制（P〈0．01），细胞凋亡率明显增加（P〈0．01），透射电镜观察到典型的细胞凋亡特征（细胞体积缩小，核皱缩、碎裂，染色质呈块状边集等）。结论TFARl9蛋白能够协同米非司酮促进前列腺癌PC-3M细胞凋亡，有望成为前列腺癌的辅助治疗药物。     

枸杞多糖对人前列腺癌PC-3细胞凋亡的影响

目的研究枸杞多糖(LBP)对人前列腺癌PC-3细胞凋亡的影响。方法体外培养的人前列腺癌PC-3细胞经枸(LBP)处理后,采用MTT法测定细胞的增殖情况,流式细胞仪分析LBP对PC-3细胞周期和凋亡的影响,TUNEL法观察PC-3细胞凋亡的变化,用免疫组化法检测其Bcl-2和Bax蛋白的表达。结果LBP可明显抑制人前列腺癌PC-3细胞的生长,并能诱导PC-3细胞凋亡,凋亡率分别为8.5%、17.5%、29.5%、37.5%和41.5%,与对照组比较,差异有非常显著性(P<0.01);同时PC-3细胞Bcl-2/Bax蛋白比值显著下降,呈明显的剂量-效应关系。结论LBP对人前列腺癌PC-3细胞DNA具有损伤作用,能诱导PC-3细胞的凋亡,调节其相关基因的表达。     

氯化镉在Balb/c 3T3细胞转化过程中对细胞凋亡的影响

目的探讨氯化镉(CdCl2)在Balb/c 3T3细胞转化过程中对细胞凋亡的影响及其分子机制。方法N-甲基-N′-硝基-N-亚硝基胍(MNNG)启动后,CdCl2持续处理Balb/c 3T3细胞14 d,建立两阶段细胞转化模型。苔盼蓝排染法检测CdCl2的细胞毒性,AnnexinV-FITC/PI双染色结合流式细胞仪检测细胞凋亡率,小鼠毒理基因芯片检测CdCl2促癌作用过程中的基因表达变化。结果1 mg/L MNNG启动后,324μg/L CdCl2持续处理能诱导细胞转化灶的出现。CdCl2处理2 d后细胞存活率降低,凋亡率显著升高。同时基因表达谱分析筛选出的差异表达基因中,有11个基因的功能与细胞凋亡有关,10个基因的功能与细胞抗氧化机制有关。结论CdCl2在促癌过程能诱导Balb/c 3T3细胞凋亡,同时影响凋亡和抗氧化相关基因的表达。     

耳针对血管性痴呆大鼠海马神经元细胞凋亡的干预研究

目的观察耳针对血管性痴呆（VD）大鼠记忆力、海马神经元细胞凋亡及凋亡蛋白酶caspase-3mRNA表达的影响,探讨耳针治疗VD的可能机制。方法采用4-血管阻断方法制备VD大鼠模型,针刺脑、肾耳穴后,morris迷宫检测大鼠学习记忆能力改善情况、原位末端标记法观察海马CA1区神经元细胞凋亡数、原位分子杂交观察促凋亡蛋白酶caspase-3 mRNA表达的变化。结果治疗组海马CA1区神经元细胞凋亡数明显减少（P〈0．01）,caspase-3 mRNA表达降低（P〈0．01）。结论耳针改善VD大鼠学习记忆能力障碍,可能与针刺下调caspase-3 mRNA的表达、抑制神经元细胞凋亡、保护缺血后海马神经元的作用有关。     

快速老化小鼠SAMP8研究进展

快速老化小鼠SAMP8(senescence-accelerated mouseprone/8)是一个从普通的遗传群AKR/J系小鼠中通过表型选择培育出的快速老化小鼠,表现为早期增龄性学习记忆缺陷,同时伴有Aβ淀粉样蛋白沉积,是目前公认的有效的研究阿尔采末病(Alzheimer’s disease,AD)动物模型。同属SAMR1表现为抗快速老化,具有正常的老化特性,常用作正常对照。目前SAMP8已被广泛应用于研究快速学习记忆缺陷的发病机制,以及评价抗衰老及改善学习记忆功能的药物等。     

运动对快速老化小鼠海马突触素表达的影响

目的研究运动对快速老化小鼠（SAMP8）海马突触素表达的影响,探讨运动改善阿尔茨海默病（AD）学习记忆功能的机制。方法 3月龄SAMP8小鼠40只随机分为运动组（采用跑笼运动训练）和对照组,2个月后HE染色观察2组海马神经元形态改变;免疫组化技术检测2组海马突触素表达。结果 5月龄SAMP8小鼠对照组海马部分神经元细胞变性、死亡,核浓缩,空泡变性;运动组偶有神经元细胞变性、死亡,大部分细胞形态正常。海马突触素表达运动组较对照组显著增高（P〈0.05）。结论运动可以延缓SAMP8小鼠海马神经元变性,提高海马突触素表达,这可能是运动改善AD学习记忆功能的重要机制之一。     

Developmental regulation of AMPA-receptor properties in CA1 pyramidal neurons of rat hippocampus

AMPA-receptor (AMPA-R) currents were recorded from CA1 pyramidal neurons in situ and after acute isolation from the hippocampus of 3- to 45-day-old rats. Membrane currents were analyzed by combining the patch clamp method with fast application techniques. The complete block of receptor currents by GYKI 53655 and the absence of modulation by Concanavalin A indicated that the cells exclusively expressed non-NMDA glutamate receptors of the AMPA subtype while functional kainate receptors could not be detected. The lowest sensitivity to kainate and NBQX was observed at postnatal day (p) 18. These changes might reflect a lower abundance of GluR1 at that developmental stage. A decrease of potentiation of receptor currents by cyclothiazide (CTZ), an acceleration of the recovery from CTZ potentiation and a faster and more complete desensitization of glutamate-evoked currents suggest an up-regulation of flop splice variants with increasing age. These functional data indicate that AMPA-R expression in CA1 pyramidal neurons varies during postnatal development which can be expected to influence the kinetics of synaptic transmission and the excitotoxic vulnerability as well.     

Strychnine-induced potassium current in CA1 pyramidal neurones of the rat hippocampus.

1. Direct actions of strychnine (Str) and brucine (Bru) on the dissociated hippocampal CA1 neurones of the rat have been investigated with the whole-cell mode of the patch-clamp technique. 2. At a holding potential (VH) of -20 mV, both Str and Bru elicited outward current at concentrations over 10(-5) M. The reversal potential of Str-induced current (EStr) was -77.8 mV, which was close to the K+ equilibrium potential (EK = -80.3 mV). The change in EStr for a ten fold change in extracellular K+ concentration was 58 mV, indicating that the membrane behaves like a K+ electrode in the presence of Str. 3. The concentration-response curves for Str and Bru were bell-shaped, and nearly maximum response occurred at 10(-4) M for Str and 3 x 10(-4) M for Bru. The maximum current amplitude induced by Bru was about 80% of that induced by Str. A transient 'hump' current appeared immediately after the wash-out of external solutions containing Str and Bru at concentrations higher than 10(-4) and 3 x 10(-4) M, respectively. 4. The Str-induced current (IStr) was antagonized by K+ channel blockers such as Ba2+, tetraethylammonium (TEA)-chloride, and 4-aminopyridine (4-AP) in a concentration-dependent manner. IStr was insensitive to glibenclamide, a blocker of ATP-sensitive K+ channels. 5. Internal perfusion with 10 mM BAPTA did not affect the Str-induced IK. Depletion of the intracellular Ca2+ store by caffeine had no effect, indicating that intracellular Ca2+ does not mediate the Str-induced activation of K+ conductance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of philanthotoxin-343 on CA1 pyramidal neurons of rat hippocampus in vitro.

A synthetic analog of philanthotoxin-433, philanthotoxin-343 (PhTX-343), was tested in hippocampal pyramidal neurons in vitro. PhTX-343 (2 microM) did not significantly change synaptic transmission mediated by AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid)/kainate receptors in the CA1 region of hippocampus. However, PhTX-343 significantly suppressed both the synaptic N-methyl-D-aspartate receptor-induced current (NMDA) obtained in the presence of CNQX(6-cyano-7-nitroquinoxaline-2,3-dione)/picrotoxin (10 microM) and the directly evoked NMDA receptor-induced current to pressure ejection of NMDA in the presence of tetrodotoxin (0.5 microM). A short transient facilitation of both types of NMDA response was seen immediately after the beginning of PhTX-343 application. Our results suggest that at high concentration (2 microM) PhTX-343 inhibits the NMDA-gated current, while the early facilitation occurred during an initial low concentration of the compound. Both facilitative and depressive actions of PhTX-343 are localized at the postsynaptic membrane.     

Effects of sodium metabisulfite on potassium currents in acutely isolated CA1 pyramidal neurons of rat hippocampus.

The effects of sodium metabisulfite (SMB), a food preservative mostly used in food and drug industries, on voltage-dependent potassium currents in acutely isolated hippocampal CA1 pyramidal neurons of rat were studied using the whole-cell patch-clamp techniques. SMB increased transient outward potassium current (IA) and delayed rectifier potassium current (IK) in a concentration-dependent manner. 10 microM SMB shifted the steady-state activation curve of IK to more negative potentials, and the steady-state inactivation curves of IA and IK to more positive potentials. Time to peak of IA was not affected, but the decay of IA was delayed by SMB. However, the activation and inactivation time constants of IK were both decreased by SMB. These results suggested that SMB differently affected IA and IK, and it would decrease the excitability of hippocampal neuron by increasing potassium currents.     

山奈酚对急性短暂缺氧时大鼠海马CA1神经元电压依赖性钾通道的作用

目的研究山奈酚对正常和急性短暂缺氧时大鼠海马CA1锥体神经元电压依赖性钾通道的作用.方法急性分离大鼠海马CA1区锥体神经元,采用全细胞记录,用含有氰化钾(KCN)60μmol·L-1的标准外液灌流模拟细胞缺氧,观察山奈酚对正常和缺氧时海马CA1区神经元电压依赖性钾通道的作用.结果山奈酚对正常和缺氧时海马CA1神经元电压依赖性K 电流有明显的抑制作用,可同时抑制瞬时外向型钾电流(IA)和延迟整流性钾电流(Ik),具有浓度依赖和电压依赖性;山奈酚对IA的半数抑制浓度(IC50)约为50μmol·L-1,对IK的IC50约为80μmol·L-1.结论山奈酚对正常和缺氧时大鼠海马CA1神经元电压依赖性钾通道有抑制作用,其对钾通道的抑制作用可能参与脑缺血保护.     

Serotonin inhibits epileptiform discharge by activation of 5-HT1A receptors in CA1 pyramidal neurons

The anti-epileptiform effect of serotonin was characterized in cellular models of epilepsy using electrophysiological recording techniques. In the bicuculline model, both serotonin (20 μM) and its 5-HT_1A agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, 10 μM) completely blocked the epileptiform discharge and caused membrane hyperpolarization and reduction in input resistance. These effects were completely antagonized by the 5-HT_1A receptor antagonist N-t-butyl-3(4-[2-methoxyphenyl]piperazin-1-yl)-2-phenyl-propanamide (WAY 100135) (10 μM). Epileptiform discharge induced by positive current injection was also blocked by serotonin. The presence of WAY 100135 renders serotonin ineffective in the same model. In the bicuculline model, epileptiform discharge blocked by serotonin reappeared and was also intensified when BaCl₂ was added to the medium. To rule out the possibility of serotonin-induced hyperpolarization strengthening the inhibitory effect of endogenous Mg²⁺ on glutamate N-methyl-D-aspartic acid (NMDA) receptor we studied the antiepileptic effect of serotonin in the 0 Mg²⁺ model. Spontaneous activity and evoked bursts seen with the OMg²⁺ model were completely blocked by serotonin. WAY 100135 completely antagonized serotonin effects in this model as well. This study provides evidence suggesting that in rat CA1 pyramidal neurons, serotonin can inhibit epileptiform activity in a variety of accepted epilepsy cellular models and that inhibition of epileptiform bursts by serotonin may be mediated by activation of the 5-HT_1A receptor subtype.     

The induced synthesis of metallothionein in various tissues of rats in response to metals. II. Influence of zinc status and specific effect on pancreatic metallothionein

Metallothionein (MT) of various tissues contains bound zinc (Zn) and any change in Zn status can alter its synthesis and tissue deposition. The changes in MT levels and its inducibility in Zn-injected and Zn-deficient (Zn-D) rats were studied. MT levels in 11 tissues (brain, lung, heart, liver, kidney, stomach, small intestine, pancreas, spleen, testes and muscle) of control and rats injected with different doses of ZnSO₄ (20 mg Zn/kg for 2, 4 or 7 times) were measured by the cadmium-hemolysate (Cd-hem) method. A dose dependent increase in MT levels was observed only in the pancreas, liver, small intestine and kidney after ZnSO₄ injection — the highest level being in the pancreas. A positive correlation was found between Zn and MT concentrations and also the relative inducibility of MT was similar in these 4 tissues (slopes of regression equations were 12.6–15.5). In order to study the effect of Zn-D in MT induction, rats were fed a diet containing 1 ppm Zn for 18 days and CdCl₂ (1 mg Cd/kg) was injected subcutaneously 3 times at 48-h intervals to control and Zn-D rats. Although the tissue distribution of Cd was similar in both the groups, MT concentrations in pancreas and kidney were significantly decreased in Zn-D. The plasma and tissue levels of Zn were also decreased in Zn-D rats injected with CdCl₂. The decrease in both Zn and MT levels was more prominent in pancreas than other organs of Zn-D rats. The results suggest that of all the organs studied, the induction of pancreatic MT is sensitive to Zn status and Zn may be a primary inducer of MT.