大鼠背根神经节分离神经元的延时整流的钾离子单通道

运用膜片钳技术对急性分离的大鼠背根神经节神经元细胞上的电压依赖性钾离子通道进行了研究.在细胞贴附式记录模式下,去极化可以激活一个电导为20pS的钾离子单通道电流,分析了其单通道的特性,提出了其动力学的模型.对于了解大鼠背根神经节神经元细胞的电活动机制具有重要的意义.     

神经节苷脂对损伤胎鼠背根神经节的保护作用

目的观察神经节苷脂(GM1)对受损伤胎鼠背根神经节(DRG)神经元形态改变的影响,探讨其可能的保护作用。方法选择胎龄为15d的SD大鼠为研究对象,获取DRG神经元并进行体外分散培养,培养48h后,随机分为对照组、谷氨酸损伤组和谷氨酸损伤+GM1保护组,继续培养12h。终止培养后,观察各组神经元的形态结构改变,用MTT法鉴定细胞的存活率。结果对照组DRG神经元细胞贴壁呈单层散在分布,少部分出现细胞聚集现象,突起较长且互相交织形成网状。谷氨酸损伤组DRG神经元细胞聚集现象明显,神经元突起变短、断裂甚至消失。谷氨酸损伤+GM1保护组DRG神经元细胞部分呈簇状聚集,部分呈单个散在分布,突起仍然相互交织。MTT结果显示谷氨酸损伤+GM1保护组细胞存活率高于谷氨酸损伤组。结论神经节苷脂可以影响损伤胎鼠DRG神经元的形态改变,对胎鼠背根神经节神经元具有一定的保护作用。     

Stimulatory Effects of NMDA on Intracellular Ca~(2 ) Nonlinear Kinetic Model in Rat Dorsal Root Ganglion Neurons

INTRODUCTION　　 The N- methyl- D- aspartate receptor( NMDAR) is a highly Ca2 permeable,lig-and- gated ion channel in neurons and a member of the ionotropic glutamate receptorfamily,Itis the famous agonistof the NMDA receptor,the latter being named afte…     

野木瓜调制背根神经节细胞钠离子通道的实验与计算机模拟

采用计算机模拟的方法, 排除膜片钳实验观察中除钠通道以外的其它离子通道对实验结果的干扰,从野木瓜注射液对背根神经节细胞钠离子通道电流和动作电位影响的角度,研究野木瓜注射液的镇痛机制.用Hodgkin Huxley模型拟合全细胞膜片钳实验所得的10%,25%和50%野木瓜注射液作用前后的膜片钳钠离子通道电流数据,进行参数估计,评价拟合优度,并将所获参数用于建立模拟神经元,在只改变模型钠离子通道参数的情况下,计算机仿真野木瓜注射液作用前后的背根神经节细胞动作电位.膜片钳实验结果表明,野木瓜注射液浓度依赖地抑制背根神经节细胞钠通道电流峰值,并影响通道的激活失活过程.计算机模拟结果表明,野木瓜注射液作用后,钠通道半激活电压向去极化方向偏移,神经元产生动作电位的刺激电流阈值提高.说明野木瓜注射液可能通过影响钠离子通道激活过程从而阻滞初级感觉神经元动作电位,干预痛觉信息的传导,从而产生镇痛效果.     

坐骨神经损伤后脊神经节神经元凋亡的形态学观察

周围神经损伤后，神经修复困难的原因之一是一定数量的神经元胞体死亡。运用NGF可保护感觉神经元胞体免于死亡，但对于细胞死亡的性质目前尚未肯定，因而对NGF的保护机理也就不清楚。本研究通过对大鼠坐骨神经切断再吻合后，观察其脊神经节感觉神经元的胞体形态变化，认为神经元死亡的主要形式是细胞凋亡(apoptosis)。     

基于GC V算法的背根节神经元放电信号的滤波

为去除背根节神经元放电信号中的噪声,便于进一步分析信号,采用小波滤波法。先将含噪信号采用haar小波进行5层分解,然后在传统小波软阈值滤波的基础上,提出用GCV算法来确定最优阈值,最后进行信号重构。通过matlab仿真实验表明,采用了GCV算法的滤波方法能有效去除神经元放电信号中的噪声,去噪后信号光滑连续好,并且保留了信号峰值的相关细节。     

备用根大鼠脊髓后角组织提取液对培养的鸡胚背根节神经突起生长的影响

应用组织培养方法，观察备用根大鼠手术侧和非手术侧脊髓后角组织提取液对鸡胚背根节神经突起生长的影响。结果显示：备用根大鼠手术侧脊髓后角组织提取液作用的背根节神经突起生长密度（１５５．２５±１４．２５）明显高于非手术侧提取液作用的背根节神经突起生长密度（８９．１４±９．６０）。提示部份去传入纤维支配的脊髓后角组织可能存在着促进神经突起生长的神经营养活性物质。     

Cytoplasmic Na+-dependent modulation of mitochondrial Ca2+ via electrogenic mitochondrial Na+-Ca2+ exchange

To clarify the role of mitochondrial Na(+)-Ca(2+) exchange (NCX(mito)) in regulating mitochondrial Ca(2+) (Ca(2+)(mito)) concentration at intact and depolarized mitochondrial membrane potential (DeltaPsi(mito)), we measured Ca(2+)(mito) and DeltaPsi(mito) using fluorescence probes Rhod-2 and TMRE, respectively, in the permeabilized rat ventricular cells. Applying 300 nm cytoplasmic Ca(2+) (Ca(2+)(c)) increased Ca(2+)(mito) and this increase was attenuated by cytoplasmic Na(+) (Na(+)(c)) with an IC(50) of 2.4 mm. To the contrary, when DeltaPsi(mito) was depolarized by FCCP, a mitochondrial uncoupler, Na(+)(c) enhanced the Ca(2+)(c)-induced increase in Ca(2+)(mito) with an EC(50) of about 4 mm. This increase was not significantly affected by ruthenium red or cyclosporin A. The inhibition of NCX(mito) by CGP-37157 further increased Ca(2+)(mito) when DeltaPsi(mito) was intact, while it suppressed the Ca(2+)(mito) increase when DeltaPsi(mito) was depolarized, suggesting that DeltaPsi(mito) depolarization changed the exchange mode from forward to reverse. Furthermore, DeltaPsi(mito) depolarization significantly reduced the Ca(2+)(mito) decrease via forward mode, and augmented the Ca(2+)(mito) increase via reverse mode. When the respiratory chain was attenuated, the induction of the reverse mode of NCX(mito) hyperpolarized DeltaPsi(mito), while DeltaPsi(mito) depolarized upon inducing the forward mode of NCX(mito). Both changes in DeltaPsi(mito) were remarkably inhibited by CGP-37157. The above experimental data indicated that NCX(mito) is voltage dependent and electrogenic. This notion was supported theoretically by computer simulation studies with an NCX(mito) model constructed based on present and previous studies, presuming a consecutive and electrogenic Na(+)-Ca(2+) exchange and a depolarization-induced increase in Na(+) flux. It is concluded that Ca(2+)(mito) concentration is dynamically modulated by Na(+)(c) and DeltaPsi(mito) via electrogenic NCX(mito).     

Substance P in Dorsal Root Ganglion Neurons in Young and Adult Rats,after Nociceptive Stimulation during the Neonatal Period

The nervous system is highly plastic during the neonatal period, being sensitive to noxious stimuli, which may cause short‐ and long‐term pain responsivity changes. Understanding plasticity in peripheral pain pathways is crucial, particularly when the nervous system is still under development and remodeling process. Substance P (SP) is widely used as a marker for peripheral neurons with unmyelinated and small myelinated fibers. We investigated the number of SP immunoreactive neurons in the dorsal root ganglion (DRG) of male and female Wistar rats, 15 and 180 days after nociceptive stimulation during the neonatal period. Right and left 5th lumbar (L5) DRG were incubated in rabbit polyclonal anti‐substance P primary followed by biotinylated donkey anti‐rabbit secondary antibodies. Reaction was revealed with a nickel‐diaminobenzidine solution. Labeled neurons were counted and compared between ages, genders and groups. Gender differences were present in both ages, with the number of SP‐positive DRG neurons being larger in 15‐days‐old males on both sides. After 180 days, males showed a larger number of SP‐positive neurons than females only on the nociceptive stimulated side. An increased number of SP‐positive neurons in the DRG on the stimulated side was present in females, immediately after nociceptive stimulation, but not after 180 days. In conclusion, neonatal noxious stimulation caused a permanent increase in SP‐positive DRG neurons in males that was not observed in females, suggesting that differences in pain processing/responsivity between genders could be related to morphological alterations of the nervous system. Anat Rec, 301:849–861, 2018. © 2017 Wiley Periodicals, Inc.     

Modulation of intracellular Na+ and Ca2+ induced by the cardiac Na+-Ca2+ exchanger in guinea pig ventricular myocytes

The Na+-Ca2+ exchanger current was measured in single guinea pig ventricular myocytes, using the whole-cell voltage-clamp technique, and intracellular free calcium concentration ([Ca2+](i)) was monitored simultaneously with the fluorescent probe Indo-1 applied intracellularly through a perfused patch pipette. In external solutions, which have levels of Ca2+ (approximately 66 microM Ca2+) thought low enough to inhibit exchanger turnover, the removal of external Na+ (by replacement with Li+) induced both an outward shift of the holding current and an increase in [Ca2+](i), even though the recording pipette contained 30 mM bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), sufficient to completely block phasic contractions. The effects of Na+ removal were blocked either by the extracellular application of 2 mM Ni2+ or by chelating extracellular Ca2+ with 1 mM EGTA. In the presence of 10 microM Ryanodine, the effects of external Na+ substitution with Li(+) on both membrane current and [Ca2+](i) were attenuated markedly in amplitude and at a much slower time course. Reversal potentials were estimated by using ramp pulses and by defining exchange currents as the Ni2+-sensitive components. The experimental values of the reversal potential and [Ca2+](i) were used to calculate cytosolic Na+ ([Na+](i)) by assuming an exchanger stoichiometry of 3Na+ : 1Ca2+. These calculations suggested that in the nominal absence of external Ca2+ ( approximately 66 microM under our experimental conditions), the exchanger operates at -40 mV as though approximately 40 mM Na+ had accumulated in the vicinity of the intracellular binding sites. We conclude that under the conditions of low extracellular Ca2+ and high intracellular Ca2+ buffering, the Na+-Ca2+ exchanger can still generate sufficient Ca2+ influx on the removal of external Na+ to markedly increase cytosolic free Ca2+.     

早期糖尿病大鼠背根节COX-2 mRNA和血中PGE2的变化

目的研究早期糖尿病背根节(DRG)中COX-2mRNA及血中PGE2的变化,进一步探讨糖尿病神经血管并发症的发病机制。方法大鼠单次注射链佐霉素60mg·kg-1制作糖尿病模型;用RTPCR技术半定量测定DRG中COX2mRNA;用放射免疫法检测血中PGE2的浓度。结果在早期糖尿病,DRG中COX2mRNA与βactinmRNA比值为0.44±0.02(1周),0.83±0.03(3周),其余对照组,4周和8周组未检出;血中PGE2的浓度分别为453.3±172.8(1周),2500±592.14(3周),380±112.3(4周)和740±173.2(8周)pg·ml-1,其中对照组未检出。结论糖尿病早期DRG中即有COX2mRNA及血中PGE2的改变,DRG中COX2mRNA的改变可能部分影响血中PGE2浓度。