轴突损伤距离对成年金黄地鼠视网膜节细胞轴突在正常或预先溃变周围神经移

目的 系统研究轴突损伤的距离与轴突再生之间的关系,以及预先溃变周围神经移植物对视网膜节细胞（简称节细胞）轴突在不同距离损伤后再生的影响。方法 在距成年金黄地鼠眼球后极０．５、１．５、２、３或７ｍｍ处切断左侧视神经,视神经眶侧断端同正常（正常组）或预先溃变（溃变组）的周围神经移植物吻合。结果 移植术后２８ｄ,两组荧光金逆行标记的发出再生轴突的节细胞数量均随轴突损伤距离的增加而下降,并以０．５～３ｍｍ距离点之间下降最为明显。比较两组对应距离点,溃变组标记节细胞数量在２、３ｍｍ距离点较正常组显著增多。结论 成年金黄地鼠节细胞轴突损伤的距离,决定了发生再生轴突的节细胞数量。预先溃变周围神经移植物对节细胞轴突再生具有促进作用,并以轴突损伤距离为条件。     

轴突损伤距离对成年金黄地鼠视网膜节细胞轴突在正常或预先溃变周围神经移植物中再生的影响

目的　系统研究轴突损伤的距离与轴突再生之间的关系 ,以及预先溃变周围神经移植物对视网膜节细胞 (简称节细胞 )轴突在不同距离损伤后再生的影响。　方法　在距成年金黄地鼠眼球后极 0 .5、1、1.5、2、3或7m m处切断左侧视神经 ,视神经眶侧断端同正常 (正常组 )或预先溃变 (溃变组 )的周围神经移植物相吻合。　结果　移植术后 2 8d,两组荧光金逆行标记的发出再生轴突的节细胞数量均随轴突损伤距离的增加而下降 ,并以 0 .5～3m m距离点之间下降最为明显。比较两组对应距离点 ,溃变组标记节细胞数量在 2、3mm距离点较正常组显著增多。　结论　成年金黄地鼠节细胞轴突损伤的距离 ,决定了发出再生轴突的节细胞数量。预先溃变周围神经移植物对节细胞轴突再生具有促进作用 ,并以轴突损伤距离为条件。     

MK-801和L-NA对成年仓鼠视网膜节细胞轴突损伤后存活与再生的影响

目的 研究NMDA受体阻断剂MK-801和一氧化氮合酶抑制剂L-NA对成年仓鼠视网膜节细胞(下称节细胞)轴突切断后存活和再生的影响。方法 切断动物左侧视神经后分两组：存活组存活2、7或14d；再生组视神经眶侧断端同一段坐骨神经吻合后存活28d。所有实验动物自视神经切断前1d开始，每日接受腹腔注射MK-801和／或LNA直至处死。结果存活节细胞均数在MK-801组与对照组间无显著性差异，但L-NA组在术后2和7d节细胞数较对照组显著增加，合用MK-801／LNA较单用MK-801或L-NA使更多节细胞存活。而MK-801或L-NA对节细胞轴突在周围神经移植物内的再生均无明显作用。结论 lmg／kg剂量的MK-801对节细胞的存活无明显作用，但同时阻断NMDA受体和抑制一氧化氮合酶比单纯抑制一氧化氮合酶对节细胞有更强的神经保护作用。1．0mg／kgMK-801或4．5mg／kgL-NA对节细胞轴突的再生无明显促进作用。     

新生犊牛视网膜节细胞的形态分布

目的:研究比较新生犊牛视网膜节细胞(RGCs)的数量、大小和密度的形态学变化。方法:采用Nissl染色、荧光染料DiI逆行标记技术和计算机图像处理方法。结果:RGCs在视神经乳头下方形成一个沿鼻颞侧轴方向伸展的高密度区(P1,2608/mm2;P21,2174/mm2),即视条纹。由视条纹至周边部细胞密度递减,颞侧周边部最低(P1,mm2;P21,217/mm2);细胞大小则呈递增的变化,这种变化趋势在颞侧最明显。由P1到P21,RGCs总数和平均细胞密度均递减而细胞大小递增。结论:RGCs大小由视条纹至周边部递增而细胞密度递减,并且由P1到P21,RGCs总数和细胞大小递增而细胞密度递减。     

小鼠脊髓损伤后Nogo-A的免疫组织化学研究

目的研究小鼠脊髓损伤后Nogo-A的表达情况。方法 C57小鼠分为脊髓损伤组、假手术组和正常对照组,每组均在损伤后不同时间点（损伤后1 h,12 h,24 h）取材,然后行Nogo-A免疫组织化学染色。结果 Nogo-A明显表达于神经元胞体及其突起形成的神经纤维。随着损伤后存活时间的延长,Nogo-A阳性细胞数量和免疫反应强度均逐渐升高。结论脊髓损伤后24 h内Nogo-A在神经元的表达逐渐升高,导致神经再生困难。     

大鼠胚胎视网膜节细胞神经诱向因子及其受体的免疫组织化学定位及原位定量研究

用视网膜节细胞神经诱向因子(RGNTF)单克隆抗体及RGNTF抗独特型单克隆抗体对大鼠胚胎16～18d眼球切片进行了免疫组织化学定位及定量研究。结果表明,鼠胚视网膜节细胞的RGNTF含量从胚16～20d非常显著地减少(P<0.01),RGNTF受体的数量从胚16d到18d显著增加(P<0.05),从胚18d到20d又非常显著减少(P<0.01)。以上提示,16～18d的鼠胚视网膜节细胞既含大量RGNTF,又有大量RGNTF的受体,RGNTF对胚胎视网膜节细胞的存活及分化可能有自调节功能。20d的鼠胚视网膜节细胞的RGNTF及其受体都非常显著减少,提示节细胞在形态上分化完成后,其对RGNTF的自分泌立即显著降低,这可能是节细胞自然死亡的主要原因。     

哺乳动物视网膜节细胞中神经营养因子的主要生物学作用

哺乳动物视网膜节细胞的存活和再生受许多神经营养因子的调节。本文综述了神经营养素家族、细胞因子家族及玻璃体内移植外周神经节段等因素促进视网膜节细胞存活的作用 ;同时也分析了它们对视网膜节细胞的轴突生长和再生的影响 ,并提出这些神经营养因子可能通过升高cAMP水平起作用。     

糖尿病小鼠视网膜碱性成纤维细胞生长因子的表达及细胞损害的电镜观察

目的：为临床研究提供形态学资料。方法：用免疫组化方法，观察碱性成纤维细胞生长因子(bFGF)在糖尿病小鼠视网膜的分布及表达密度；用透射电镜观察不同病程视网膜细胞的损害情况。结果：糖尿病及正常小鼠视网膜各层细胞均表达bFGF，反应强度和密度不同。发病组自6月龄起，居于大血管周围的阳性节细胞密度增加；不同病程bFGF的表达有不同程度的增加。随糖尿病病程延长，细胞超微结构受到不同程度的损害。结论：糖尿病时增多的bFGF直接或间接作用于血管内皮细胞和平滑肌细胞，刺激二者增殖，促进微血管病变的发生；另一方面，减弱视细胞与双极细胞间的信息传递，对糖尿病性盲的发生起重要作用。同时，各种细胞的超微结构及相应的功能也受到不同程度的损害。     

Response of X and Y cat retinal ganglion cells to moving stimuli

Summary Single optic tract fibers in the cat were classified as X or Y cells by a contrast reversal stimulus. A slit of light was then moved across the receptive field at velocities from 10–1000 ° /s. The preferred velocity was that velocity which elicited the strongest response from the cell. The maximum velocity was the highest velocity target to which a cell could respond. Y cells as a group both preferred and could follow faster targets than X cells, and were more broadly tuned to the preferred velocity.This study was supported by Public Health Service Grant EY 00701 and NEI Grant EY 00376     

远志皂苷元对氧化应激损伤的视网膜神经节细胞的保护作用

目的: 观察远志皂苷元(senegenin,Sen)对氧化应激损伤的视网膜神经节细胞(retinal ganglion cells,RGCs)的影响并初步探讨其作用机制。方法: 采用上丘荧光金逆行标记RGCs后,体外原代RGCs混合细胞培养,随机分为control组、H₂O₂组、Sen+H₂O₂和Sen组。检测带荧光金荧光细胞的活力。同上述分组处理视网膜,用Hoechst 33258 染色后观察视网膜细胞核形态的变化,Western blotting检测视网膜细胞cleaved caspase-3、细胞色素C及Bcl-2蛋白的表达。结果: 与control组比较,Sen浓度在10、20和40 μmol/L时, RGCs活力无明显变化(P>0.05),但Sen浓度达到80和160 μmol/L时,RGCs活力明显下降,差异显著(P<0.01)。25、50、100和200 μmol/L H₂O₂明显降低RGCs活力(P<0.05)。Sen浓度在10、20和40 μmol/L时,对50 μmol/L H₂O₂损伤的RGCs有较好的保护作用(P<0.05),其中40 μmol/L Sen保护作用最为明显。Hoechst 33258染色表明Sen可以减少H₂O₂引起的视网膜细胞凋亡。Western blotting结果表明Sen促进Bcl-2蛋白的表达,降低线粒体细胞色素C的释放,下调cleaved caspase-3的表达。 结论: Sen保护RGCs对抗氧化应激引起的损伤,其机制可能与其增强Bcl-2蛋白表达和减少氧化应激引起的细胞凋亡有关。     

rd1小鼠视网膜退变中期节细胞功能的变化

 目的:探讨视网膜色素变性模型rd1小鼠视网膜退变中期各类视网膜节细胞(retinal ganglion cells, RGCs)功能的变化情况。方法:运用多电极阵列(multi-electrode arrays,MEA)记录方法,记录视网膜退变中期(出生后20 d,P20)的rd1小鼠或正常对照小鼠视网膜中多个节细胞动作电位的发放,并比较自发发放和光反应特征等指标,评价幸存的节细胞功能变化。另外,采用免疫组化染色方法验证视网膜感光细胞的退化情况。结果:免疫组化的结果表明rd1小鼠视网膜感光层的厚度显著低于正常小鼠。根据节细胞光反应特性的不同,可以将其分成6类:ON sustained、ON transient、ON-OFF sustained、ON-OFF transient、OFF sustained和OFF transient RGCs,但OFF sustained RGCs所占比重极小(1.0%~3.1%)。rd1小鼠视网膜中保持光反应的节细胞比例显著低于正常小鼠。rd1小鼠节细胞的自发发放显著高于正常小鼠,而不同类型的节细胞变化情况有所不同。rd1小鼠视网膜各类节细胞的光反应强度及光敏感度均显著低于正常小鼠。结论:在rd1小鼠退变的中期,视网膜感光层明显退变;rd1小鼠退变中期的视网膜节细胞发生明显的功能退变,而且不同类型的节细胞变化情况有所不同。     

原花青素对微波诱导视网膜神经节细胞凋亡的拮抗作用

目的： 探讨不同剂量的原花青素(procyanidin，PC)对微波致视网膜神经节细胞（retinal ganglion cells，RGCs）损伤的拮抗作用。方法: 体外培养RGCs，将细胞随机分为6组，即不同PC剂量(0 μg/L 、2 μg/L、20 μg/L和40 μg/L)4个实验组及维生素C 40 μg/L组和对照组，分别给予频率为2 450 MHz、功率密度为30 mW/cm2的微波连续辐照1 h，对照组不给予辐照。光镜下观察辐照前后细胞形态学的改变，台盼蓝染色检测细胞存活率，应用流式细胞仪和DNA末端标记法(TdT-mediated-dUTP nick end labeling，TUNEL)定量检测细胞早期凋亡。结果: 微波辐照后，细胞即有聚集现象，部分细胞突起消失。辐照后0 h，20 μg/L和40 μg/L PC组较0 μg/L PC组的细胞凋亡率有所降低(P<0.05)；辐照后6 h和12 h，3个PC剂量组较0 μg/L PC组的细胞凋亡率都有降低(P<0.05)；辐照后18 h，只有40 μg/L PC组较0 μg/L PC组的细胞凋亡率显著降低(P<0.01)。结论: 微波可诱导RGCs细胞凋亡，PC对此损伤具有一定的拮抗作用。     

Response of cat retinal ganglion cells to motion of visual texture

Summary Responses of retinal ganglion cells to motion of large fields of visual texture were recorded in the lightly anaesthetised, immobilized cat. Brisk sustained and brisk transient, on- or off-centre, units gave a modulated response to texture motion. The pattern of temporal modulation of the response was dependent upon the particular configuration (sample) of texture crossing the receptive field. The magnitude of the response depended on the size of the receptive field centre. For all units, whether sustained or transient the magnitude of response to a textured field of fixed angular subtense declined as centre-diameter increased from 0.9 deg. For brisk units the response magnitude levelled off for centre sizes smaller than 0.9 deg. Responses to texture were confined spatially to the region of the receptive field, and the overall characteristics of this response were due to interactions between the centre and surround mechanisms of the receptive field. In brisk transient units, no evoked response was evident when texture motion was confined to regions well away from the receptive field of the unit, i.e. no periphery or shift effect could be demonstrated. The results support previous suggestions that the differential sensitivity to texture motion evident in cortical neurones must be due to intra-cortical processing.Supported by Project Grant G978/558/N from the Medical Research Council     

Orientation bias of cat retinal ganglion cells: a reassessment

Summary For cat retinal ganglion cells whose receptive field centres were distributed in specified sections of the left visual field, the deviations of the major axis from the radial, horizontal, and circumferential directions were determined. The percentage of cells with deviations within ± 20° from the radial, horizontal, and circumferential directions were, respectively, 33%, 68%, 16%. In addition, comparison between values of deviation from the horizontal direction for cells located at eccentricities of 10° and 20° from the area centralis showed a statistically significant trend: the bias for the horizontal increased with eccentricity.     

Rescuing axons from degeneration does not affect retinal ganglion cell death

After a traumatic injury to the central nervous system, the distal stumps of axons undergo Wallerian degeneration (WD), an event that comprises cytoskeleton and myelin breakdown, astrocytic gliosis, and overexpression of proteins that inhibit axonal regrowth. By contrast, injured neuronal cell bodies show features characteristic of attempts to initiate the regenerative process of elongating their axons. The main molecular event that leads to WD is an increase in the intracellular calcium concentration, which activates calpains, calcium-dependent proteases that degrade cytoskeleton proteins. The aim of our study was to investigate whether preventing axonal degeneration would impact the survival of retinal ganglion cells (RGCs) after crushing the optic nerve. We observed that male Wistar rats (weighing 200-400 g; n=18) treated with an exogenous calpain inhibitor (20 mM) administered via direct application of the inhibitor embedded within the copolymer resin Evlax immediately following optic nerve crush showed a delay in the onset of WD. This delayed onset was characterized by a decrease in the number of degenerated fibers (P<0.05) and an increase in the number of preserved fibers (P<0.05) 4 days after injury. Additionally, most preserved fibers showed a normal G-ratio. These results indicated that calpain inhibition prevented the degeneration of optic nerve fibers, rescuing axons from the process of axonal degeneration. However, analysis of retinal ganglion cell survival demonstrated no difference between the calpain inhibitor- and vehicle-treated groups, suggesting that although the calpain inhibitor prevented axonal degeneration, it had no effect on RGC survival after optic nerve damage.     

Classification of cat retinal ganglion cells into X- and Y-cells with a contrast reversal stimulus

Summary A contrast reversal (alternating phase) stimulus was used to study the responses of 150 retinal ganglion cells from 15 adult cats. Because the majority of the cells did not show perfect linear spatial summation, a ratio of the firing rates at two time periods was used to express the degree of nonlinearity. Y-cells showed a high degree of nonlinearity, and their mean null ratio was significantly lower than that of X-cells. With the stimulus at the null position, X-cells had an unmodulated discharge rate which was significantly higher than maintained activity, while the firing rate of Y-cells was lower than maintained activity. With the stimulus placed at an eccentric position in the receptive field, X-cells responded in a sustained manner, while Y-cells respond transiently. Because of these observations, we conclude that X-cells correspond to the sustained cells, while Y-cells correspond to the transient cells.     

基因重组碱性成纤维细胞生长因子对大鼠视网膜神经节细胞的影响

目的:研究基因重组碱性成纤维细胞生长因子(rbFGF)对大鼠视网膜神经节细胞(RGCs)的影响。方法:大鼠在视神经部分损伤后,球后注射生理盐水、维生素B₁₂、rbFGF,伤后4周进行轴突定量、视网膜神经节细胞定量以及RGCs凋亡的检测,观察视神经损伤修复情况。结果:伤后4周时,生理盐水和维生素B₁₂对RGCs无挽救作用,800U、1600U和2400U的rbFGF对RGCs挽救率分别为24.5%、27.3%、28.5%,800UrbFGF组、1600UrbFGF组和2400UrbFGF组未发生溃变的轴突数分别是损伤未治疗组的2.03、2.43、2.31倍。流式细胞仪检测结果显示:rbFGF治疗7d后,RGCs凋亡率显著减少。结论:rbFGF可提高视网膜神经节细胞的存活率,减少轴突溃变,有抗凋亡作用,对视神经损伤有显著的促功能修复作用。     

Statistical dependence between neighboring retinal ganglion cells in goldfish

Summary Simultaneous recordings were made of the spontaneous discharge of neighboring retinal ganglion cells in goldfish. Crosscorrelation analysis indicates two types of correlation. Neighboring units with like receptive field organization tend to discharge together while units having complementary receptive field organization tend not to discharge together.