从环磷酸腺苷通路研究氯胺酮对学习记忆的影响

背景 大量的研究表明,环磷酸腺苷反应元件结合蛋白(cAMP response element binding protein,CREB)直接或间接激活相关基因转录,在学习记忆等方面发挥重要作用.另外,研究证实受环磷酸腺苷(cyclic AMP,cAMP)调节的下游蛋白CREB参与了氯胺酮导致未成年大鼠学习记忆障碍的形成. 目的 研究氯胺酮与cAMP通路及相关调控蛋白细胞外调节激酶(extracellular signal regulating kinase,ERK)对学习记忆的影响. 内容 cAMP激活蛋白激酶A(protein kinase A,PKA)磷酸化并激活CREB,后者是一种重要的核蛋白,其调节启动子中具有环磷酸腺苷反应单元(cAMP response element,CRE)的基因转录,这种核转录因子具有调节包括学习记忆在内的广泛的生物学功能.趋向 希望从cAMP通路和ERK通路中,摸索一条治疗氯胺酮导致的学习记忆障碍的新途径.     

Wnt信号通路调控细胞癌变的分子开关:T细胞因子

Wnt信号通路在调控胚胎发育和决定细胞命运方面具有重要作用。T细胞因子 (TCF)是Wnt信号通路中的关键信号分子 ,最初是作为淋巴转录因子被克隆发现 ,近来研究表明 ,T细胞因子家族成员在多种发育和分化过程中起关键的转录调节作用 (转录激活或转录抑制 ) [1] 。当缺乏Wnt信号时 ,TCF与转录抑制因子如Groucho蛋白、cAMP效应元件 (CREB)结合蛋白 (CBP)及C末端结合蛋白 (CtBP)结合 ,抑制靶基因的转录表达 ;然而 ,Wnt信号激活后 ,TCF与Wnt通路信号分子 β 连环蛋白 (β catenin)结合则发挥其转录激活功能。随着研究的深入 ,T细胞因…     

足细胞表达有功能的代谢型谷氨酸受体1和5

目的 研究足细胞是否表达有功能的代谢型谷氨酸受体（mGluR）。 方法 以RT-PCR法检测基因表达,Western印迹、免疫荧光双染色和免疫电镜检测蛋白质表达。酶免疫实验（EIA）、电泳迁移位移实验（EMSA）和Western印迹法检测细胞环腺苷酸（cAMP）的产生和转录因子cAMP反应元件结合蛋白（CREB）的活化。激光共聚焦显微镜观察细胞内游离钙的变化。 结果 足细胞表达mGluR1和5的基因和蛋白质,肾小球中mGluR1的表达和足细胞标志蛋白synaptopodin表达共定位。免疫电镜显示mGluR1位于足细胞体和足突细胞膜下层。mGluR1和5的激动剂3,5-二羟基苯甘氨酸（DHPG）诱导足细胞快速地产生cAMP,转录因子CREB被激活,磷酸化CREB表达增高。这些改变能被mGluR1和5的选择性抑制剂1-氨基茚-1,5-二羧酸（AIDA）以及腺苷酸环化酶抑制剂（SQ22536）抑制,而2-氨基乙氧化联苯-甲硼烷（2APB）则不具有上述抑制作用。DHPG诱导足细胞内游离钙缓慢持续地增加,细胞孵育于不含钙的培养液中、AIDA预处理以及2APB预处理抑制了DHPG诱导的细胞内游离钙离子增加。 结论 足细胞表达有功能的mGluR1和5。     

分子生物学常用术语浅解

1.操纵子(ｏｐｅｒｏｎ)　是基因表达的单位,它包括结构基因和控制基因表达的元件。2.启动子(ｐｒｏｍｏｔｏｒ)　又称启动基因,是ＤＮＡ分子上可与ＲＮＡ聚合酶特异结合,而使转录开始的一段ＤＮＡ序列,但启动子本身并不被转录。3.转录子(ｔｒａｎｓｃｒｉｐｔｏｎ)　是指由2个和2个以上紧密连锁的并供同转录在一种ｍＲＮＡ分子中的结构基因组成的复合单位。4.增强子(ｅｎｈａｎｃｅｒ)　是另一个与转录有关的基因结构,其作用是使启动子发动转录的能力大大增强,是许多真核基因高效表达不可缺少的调控因子。5.内含子(ｉｎｔｒｏｎ)　ｍＲＮＡ…     

氯胺酮抑制昆明小鼠扣带后回Fos表达

目的 探讨慢性氯胺酮使用对扣带后回c -Fos与磷酸化的转录因子环磷酸腺苷反应元件结合蛋白(cAMP responsive element binding protein,CREB)的影响.方法 成年昆明小鼠,采用随机数字表法分组:腹腔注射50、100、200 mg/kg组以及生理盐水组,5d给药1次,共注射6次后4％多聚甲醛灌注固定、取脑、30μm冰冻切片,应用免疫组化法检测c-Fos和磷酸化cAMP反应元件结合蛋白(phosphorylated cAMP responsive element binding protein,pCREB)的表达.结果 ①扣带后回和压部后皮质有一定的c -Fos与pCREB基础;②氯胺酮慢性使用扣带后回神经元的c-Fos表达减少,50 mg/kg组、100 mg/kg组、200 mg/kg组分别下降到生理盐水组的80％、43％和37％.而pCREB的表达增加,50 mg/kg组、100 mg/kg组、200 mg/kg组分别增加到生理盐水组的180％、195％和170％.结论 慢性氯胺酮使用抑制昆明小鼠扣带后回神经元c-Fos表达,其抑制可能与pCREB表达增加有关.     

piRNA在小鼠雄性生殖系统中的起源与功能

PIWI相互作用RNA(pi RNA)是2006年新发现的一种24~32个碱基长度的非编码小RNA。pi RNA与生殖特异的PIWI蛋白结合,在生殖系统的发育中起重要作用。雄性小鼠的生殖系统中,基因组中pi RNA簇和转座子区域转录出pi RNA前体,pi RNA前体出核后在初级生成途径和次级生成途径下生成成熟的pi RNA。成熟pi RNA首先能够沉默逆转座子转录出的RNA,降低转座子的活跃度,从而维持基因稳定,维持生殖细胞的正常发育。另外pi RNA还具有调节基因表达的功能,在转录水平和转录后水平上参与精子发生。     

丙泊酚对大鼠海马cAMP效应元件结合蛋白磷酸化和cAMP效应元件结合蛋白mRNA表达水平的影响

目的 探讨丙泊酚对大鼠海马cAMP效应元件结合蛋白(cAMP response element binding protein,CREB)磷酸化和CREB mRNA表达水平的影响.方法 成年雄性SD大鼠64只,体重250 g～280 g,采用RandA1.0随机分组软件将实验动物随机分为2组(每组32只),丙泊酚组(P...     

可调控的肝癌特异性基因治疗载体的构建

目的　构建新型AFP顺式作用元件调控的基因表达载体 ,检测该调控元件的特异性和可调控性。方法　PCR扩增截短的AFP基因启动子、增强子 ,将上述片段与含有报告基因强化绿色荧光蛋白基因的载体pEGFP 1的多克隆位点连接 ,构建成为AFP基因顺式作用元件调控的肝癌特异性EGFP表达载体 (pEGFP 1 EP)。用脂质体法将表达载体转染表达或不表达AFP的肿瘤细胞系 ,荧光显微镜观测重组AFP顺式作用元件的启动活性 ,并用流式细胞术检测全反式视黄酸对它的抑制作用。结果　成功地将AFP基因启动子、增强子克隆到报告基因载体pEGFP 1的多克隆位点 ,酶切鉴定和DNA序列分析无误 ,荧光显微镜观测证实EGFP能在AFP阳性肝癌细胞特异性表达 ,1× 10 -7M全反式视黄酸对其活性有明显的抑制。结论　AFP顺式作用元件修饰的基因治疗载体 ,在基因转录水平特异性调控目的基因的表达 ,为下一步将其作为肝癌基因治疗载体奠定了基础。     

DNA甲基化和组蛋白修饰在肿瘤中的作用

在肿瘤的形成过程中包含两大类机制,基因机制(genetic mechanism)和表观基因机制(epigenetic mechanism).基因机制包括基因突变、染色体丢失和重排,产生结构异常的基因产物;表观基因机制主要指DNA5胞嘧啶甲基化,引起基因表达异常而DNA序列及基因产物不变.近几年来许多学者发现,组蛋白甲基化、乙酰化、磷酸化和泛素化等修饰导致染色质重构而抑制抑癌基因表达也是表观基因改变的一个重要机制.1999年,Alan Wolffe[1]将表观基因改变定义为"未发生DNA序列改变的可遗传的基因表达改变."     

Myocardin基因与勃起功能障碍相关的研究进展

<正>心肌素(Myocardin)又称为心肌蛋白,限制性表达于心脏和平滑肌细胞中,为血清应答因子(serum response factor,SRF)的核转录共激活因子,可通过共激活SRF后与CAr G顺式反应元件结合形成三元复合物,从而激活一系列受到SRF调控并且可以编码平滑肌细胞骨架蛋白以及收缩蛋白的基因发生转录过程~([1])。Myocardin可调节许多与细胞分化、增殖和迁移等功能相关基因的表达,在调控平滑肌细胞表型     

H-89对坐骨神经结扎大鼠触诱发痛和脊髓背角磷酸化CREB表达的影响

Neuropathicpain(NP)resultingfromvariousetiolo giessharessimilarcharacteristicfeatures :persistentspon taneouspain (burningpain) ,hyperralgesia(exaggeratedpaintonoxiousstimuli)andallodynia(paintoinnocuousstimuli) .NPisanareaoflargelyunmettherapeuticneed .Thecurrentpharmacologicalmainstaysofclinicalmanagementaretricyclicanti depressantsandcertainan ti convulsants ,1buttheseonlyachieveclinicallysignifi cant (greaterthan 5 0 %)painreliefinlessthan 5 0 %ofpatientsandareassociatedwithsub optimalsid…     

Age-dependent Responses to Nerve Injury- induced Mechanical Allodynia

Background: Developmental differences in responses to acute and chronic nerve injury have received minimal attention. This study examines developmental differences in behavioral responses to a proximal (closer to the spinal cord) (L5 and L6 spinal nerve root ligation) or to a more distal (closer to peripheral innervation) (partial sciatic nerve ligation) nerve injury in rats paralleling the infant to young adult human.

Methods: Withdrawal thresholds to von Frey filament testing in the hind paw were determined before and various times after either spinal nerve root ligation or partial sciatic nerve ligation in rats aged 2, 4, and 16 weeks. Control rats of these ages were observed serially without surgery. Times for withdrawal thresholds to mechanical stimuli to return to 80% of that of the hind paw in the control animals were compared among the different ages in the two models.

Results: Baseline withdrawal thresholds in younger rats were lower (P < 0.05). In the 2-week-old animals, distal injury partial sciatic nerve ligation did not cause a reduction in withdrawal threshold from baseline. This was different from the spinal nerve root ligation group and the older animals in the partial sciatic nerve ligation group. However, when compared with age-matched control animals, both nerve injuries resulted in reduced withdrawal thresholds (P < 0.05). The resolution of hypersensitivity to mechanical stimulation, as measured by return of threshold to 80% of controls, occurred more quickly in 2-week-old than in 4- and 16-week-old animals in both injury models (P < 0.05).     

Age-dependent responses to nerve injury-induced mechanical allodynia

BACKGROUND: Developmental differences in responses to acute and chronic nerve injury have received minimal attention. This study examines developmental differences in behavioral responses to a proximal (closer to the spinal cord) (L5 and L6 spinal nerve root ligation) or to a more distal (closer to peripheral innervation) (partial sciatic nerve ligation) nerve injury in rats paralleling the infant to young adult human. METHODS: Withdrawal thresholds to von Frey filament testing in the hind paw were determined before and various times after either spinal nerve root ligation or partial sciatic nerve ligation in rats aged 2, 4, and 16 weeks. Control rats of these ages were observed serially without surgery. Times for withdrawal thresholds to mechanical stimuli to return to 80% of that of the hind paw in the control animals were compared among the different ages in the two models. RESULTS: Baseline withdrawal thresholds in younger rats were lower (P < 0.05). In the 2-week-old animals, distal injury partial sciatic nerve ligation did not cause a reduction in withdrawal threshold from baseline. This was different from the spinal nerve root ligation group and the older animals in the partial sciatic nerve ligation group. However, when compared with age-matched control animals, both nerve injuries resulted in reduced withdrawal thresholds (P < 0.05). The resolution of hypersensitivity to mechanical stimulation, as measured by return of threshold to 80% of controls, occurred more quickly in 2-week-old than in 4- and 16-week-old animals in both injury models (P < 0.05). CONCLUSION: These data suggest that resolution of sensitization to A-fiber input occurs more rapidly in young animals. In addition, distal injury has less of a sensitizing effect on A-fiber input than proximal injury in the younger animals. The authors speculate that neuroimmune responses, especially at the site of injury, are developmentally regulated and less likely to produce chronic pain when injury occurs at a young age.     

Anti-hyperalgesic effect of CaMKII inhibitor is associated with downregulation of phosphorylated CREB in rat spinal cord

Purpose  

Calcium/calmodulin-dependent protein kinase (CaMK) II and its downstream effector cyclic adenosine monophosphate (cAMP) responsive element binding protein (CREB) may be involved in the development of neuropathic pain. The aim of this study was to examine the effect of the CaMKII inhibitor AIP on the association of CaMKII and CREB in a partial sciatic nerve ligation neuropathic pain model in rats.     

Intrathecal lidocaine reverses tactile allodynia caused by nerve injuries and potentiates the antiallodynic effect of the COX inhibitor ketorolac

BACKGROUND: Systemic lidocaine and other local anesthetics reduce hypersensitivity states induced by both acute inflammation and peripheral nerve injury in animals and produce analgesia in some patients with chronic pain. The mechanisms underlying the antiallodynic effect of systemic lidocaine are unclear, although most focus is on peripheral mechanisms. Central mechanisms, particularly at the spinal dorsal horn level, are less known. In this study, the authors aimed to determine whether intrathecal lidocaine has an antiallodynic effect on established mechanical allodynia in two well-characterized neuropathic pain rat models: partial sciatic nerve ligation (PSNL) and spinal nerve ligation (SNL). METHODS: Lidocaine (100-300 micro g) was intrathecally injected in PSNL and SNL rats. The withdrawal threshold of both hind paws in response to mechanical stimulation was measured using a series of calibrated von Frey filaments. RESULTS: This single injection reduced ongoing tactile allodynia in PSNL and SNL rats. The antiallodynic effect of intrathecal lidocaine lasted longer in PSNL (> 3 days) than in SNL rats (< 3 days). Intraperitoneal lidocaine (300 micro g) had no effect on tactile allodynia in PSNL rats. In SNL rats, prior intrathecal lidocaine (200 and 300 micro g) potentiated the antiallodynic effect of intrathecal ketorolac, a nonselective cyclooxygenase inhibitor. Intrathecal ketorolac alone had no antiallodynic effect on SNL rats. However, prior intrathecal lidocaine (100 micro g) failed to potentiate the antiallodynic effect of intrathecal ketorolac. CONCLUSION: The authors' data suggest that intrathecal lidocaine possibly suppressed the hyperexcitability of the dorsal horn neurons and likely interacted with eicosanoid systems in the spinal dorsal horn.     

Adenoviral gene transfer in the peripheral nervous system

Background Viral vectors have gained widespread use as vehicles for somatic gene transfer, and the targeted expression of foreign proteins by these vectors offers advantages over the systemic administration of the drugs in some therapeutic situations. Selective virus-mediated gene transfer to the peripheral nervous system (PNS), however, remains to be established. There are no data showing efficiency of protein transduction in the PNS, which consists of a variety of cell types, many of which are postmitotic. Methods We prepared the first-generation replication-deficient recombinant adenovirus vectors engineered to express LacZ. Eight-week-old Wister rats were used in this study. Adenovirus vector (5 μl) containing the LacZ gene (5 × 10⁸ pfu) was injected into rat sciatic nerves or the dorsal root ganglia at the level of L5. The sciatic nerves, the dorsal root ganglia, and the spinal cords were obtained 7, 14, 21, and 28 days after injection. Expression of LacZ was assessed by X-gal histochemistry and β-gal immunohistochemistry. Results Following injection of the adenovirus carrying the LacZ gene into the sciatic nerve, LacZ expression was seen mainly in the Schwann cells and the small neurons in the dorsal root ganglion. In contrast, expression was observed in the primary nerve terminals of the spinal dorsal horn and the small to large dorsal root ganglion neurons and the Schwann cells after injection of the vectors into the L5 dorsal root ganglion. There were no side effects in rats with injection in the dorsal root ganglia or the sciatic nerve. Conclusions The present study shows efficient protein transduction by adenovirus vectors in the PNS. It is noted that injection of the virus into the dorsal root ganglia leads to extensive expression of LacZ in the spinal cord, the dorsal root ganglia, and the sciatic nerves.     

坐骨神经损伤对背根节细胞凋亡及细胞凋亡相关蛋白表达的影响

目的：观察大鼠坐骨神经条件性损伤后对背根节细胞凋亡及细胞凋亡相关蛋白表达的影响。方法：将45只成年Wistar大鼠,按手术的不同随机分为3组;正常对照组（A组,n=5）;坐骨神经压榨伤组（B组,n=20);坐骨神经切断组（C组,n=20)。B、C两组又按术后3d,2周,1个月和2个月取材时间分为4个时间组,每组5只大鼠。各时间组取鼠的L5背根神经节后,以TUNEL法检测细胞的凋亡数,以免疫组化技术检测Bcl-2和Bax的表达。结果：正常组及B、C两组伤后3d时未检出凋亡细胞;B、C两组的细胞凋亡率在伤后2周达到高峰,以后随时间的推移而逐渐降低。C组的细胞凋亡率明显高于B组。背根节细胞凋亡相关蛋白Bcl-2及Bax的表达,伤后2周达到高峰。B组中Bcl-2和Bax的表达呈现从低到高而后逐渐恢复正常的规律;而C组的表达始终保持在高水平。结论：细胞凋亡相关蛋白Bcl-2和Bax参与外周神经损伤后背根节细胞凋亡的调节。外周神经的不同损伤方式对背根节细胞凋亡及细胞凋亡相关蛋白的表达影响不同。     

生物素葡聚糖胺观测周围神经局部轴突运输的实验研究

目的 研究神经示踪剂生物素葡聚糖胺（BDA）用于直观观察周围神经局部轴突运输的可行性。方法 （1）显露双侧兔坐骨神经，于实验侧及对照侧坐骨神经干注射不同浓度、不同剂量BDA，对照侧注射生理盐水，术后6、12、24、48h取样。于光镜及共聚焦显微镜下观察样本。（2）将兔左侧坐骨神经横断损伤并缝合，分别于术后1～6周于损伤近侧神经干注射10％BDA，12h后取标本观察。结果 10％BDA可清晰地在周围神经轴突内显像，操作简单，结果易于观察。同时，坐骨神经断伤术后3周时有明确的轴浆运输的恢复。结论 BDA神经干局部注射后能较清楚而直观地显示局部轴突运输的情况。     

银杏叶提取物对大鼠坐骨神经切断后HSP 70在脊髓与脊神经节中表达的影响

目的 研究周围神经损伤后脊髓热休克蛋白(heat shock proteirns,HSPs)的表达变化,及银杏叶提取物EGb 761对其影响,探讨银杏叶提取物对周围神经损伤的保护机制.方法 取成年雄性SD大鼠144只,随机分成三组:对照组、坐骨神经切断组、坐骨神经切断+银杏叶提取物干预组[术后每天用EGb 761(100 mg·kg-1*d-1,溶于2 ml SAL)灌胃,直到取材],每组48只.术后6 h、12 h、1 d.2 d,4 d、7 d、14 d、28 d取L4～6节段脊髓节段,采用免疫组织化学方法检测HSP 70在脊髓前角及脊神经节中的表达.结果 正常大鼠脊髓与神经节中均有少量HSP 70表达,在坐骨神经切断后表达迅速增加,持续一段时间后又回到正常水平,用EGb 761干预后,HSP 70表达早期较未干预组表达低,后期表达增高,且表达持续时间长.结论 银杏叶提取物EGb 761可以增加神经损伤后HSP 70表达,可能是银杏叶提取物保护神经,促进神经再生作用的机制.