马桑内酯致痫大鼠海马神经细胞外Na+、K+活度的变化

目的和方法：应用Na⁺、K⁺选择性微电极检测马桑内酯致痫大鼠海马及海马脑片神经细胞外Na⁺、K⁺活度的改变。结果：海马内注射马桑内酯（5 μL,5×10^-4 mol/L）致痫大鼠30 s、1 min和2 min后,海马神经细胞外Na⁺活度分别低于对照组27.7 mmol/L、50.3 mmol/L和57.8 mmol/L,而K活度则分别高于对照组2.3 mmol/L、2.4 mmol/L和2.9 mmol/L（P<0.01）。3 min后,K⁺活度基本恢复至对照水平,而Na⁺活度仍持续低于对照水平（P<0.01）。海马脑片的实验结果与在体实验相似。结论：海马神经细胞处于癫痫状态时,存在Na⁺内流、K⁺外流现象。     

马桑内酯致痫后大鼠海马生长抑素mRNA表达的变化

为探讨马桑内酯致痫与生长抑素的关系，用原位杂交组织化学法研究了马桑内酯致痫后大鼠海马生长抑素ｍＲＮＡ阳性神经元的变化，结果表明：致痫组大鼠ＣＡ１，ＣＡ２区及齿状回生长抑素ｍＲＮＡ的反应明显增强，以上各区的中，小神经内生长抑素ｍＲＮＡ神经元的数目及强度明显高于正常对照组，两者有显著性差异。     

马桑内酯致痫大鼠海马神经元丢失及化学性质的研究

为观察癫痫发作过程海马神经元丢失细胞的主要死亡方式 ,用马桑内酯建立慢性致痫大鼠模型 ,以 Nissl染色、免疫组化、TUNEL法以及后二者相结合的技术 ,对海马神经元及其中的抑制性神经元的丢失进行了分区观察、统计、分析。结果发现 :致痫组海马各区神经元较对照组明显减少 ,不同区域减少程度不同 ,以齿状回减少最为明显 ;免疫组化结果显示 ,致痫组的抑制性神经元 GABA-IR神经元、PV-IR神经元、CB-IR神经元在海马各区有不同程度的减少 ,其中 GABA-IR神经元减少最明显。在海马各区所有丢失的神经元中 ,三种抑制性神经元所占的比例不同 ;并在海马各区均可见到 TUNEL -GABA、TUNEL-PV、TU NEL-CB双重反应阳性神经元。提示 :马桑内酯所致的癫痫发作 ,可引起海马神经元丢失 ,且不同区域丢失的程度不同 ,丢失的神经元可能以凋亡方式为主 ;海马抑制性神经元 GABA-IR、PV-IR、CB-IR神经元在癫痫发作过程中也有不同程度的丢失 ,丢失很可能也是以凋亡形式为主     

谷氨酸钠致痫大鼠海马mGluR5的表达变化

本研究目的为探讨谷氨酸钠(GluNa)诱导大鼠癫痫发作时海马mGluR5的表达变化。将动物随机分为正常对照组、Glu—Na致痫组及D—AP-5(非竞争性：NMDA受体拮抗剂) GluNa组。通过免疫组织化学方法观察了多克隆抗体抗mGluR5在海马各区及齿状回的免疫反应阳性细胞的变化，同时观察并记录各组大鼠的行为变化。结果证明：GluNa注射后的大鼠均出现严重的癫痫发作。正常组大鼠海马中有丰富的mGluR5表达，以齿状回颗粒细胞层和CA1锥体细胞层的表达为最高，而GluNa致痫组海马各区mGluR5表达明显下调。D—AP-5 GluNa组海马各区mGluR5表达较之GluNa致痫组又上调。同时观察到三个组的mGluR5的表达主要集中在细胞膜上。结果提示mGluR5在癫痫发作后表达下降可能在癫痫诱导过程中具有重要作用，其作用机制可能为NMDA受体依赖性的。     

海马内微量注射硫酸镁对马桑内酯诱发大鼠痫样放电的影响

目的和方法:采用皮层应用或海马内注射马桑内酯的方法致痫大鼠,用钙离子选择性微电极检测了致痫动物皮层、海马细胞外Ca2+浓度的变化,观察了海马CA2区注射硫酸镁对致痫大鼠脑电图和皮层、海马诱发电位的影响.结果:马桑内酯致痫时,皮层、海马细胞外Ca2+浓度分别降低了0.61 mmol·L-1和0.74 mmol·L-1,海马内注射硫酸镁能明显地抑制致痫动物皮层、海马诱发电位和脑电图痫样放电.结论: 镁盐的上述作用可能与抑制Ca2+流入神经元内有关.     

致痫剂马桑内酯引起培养的大鼠皮层神经细胞凋亡

用有致痫作用的马桑内酯处理培养的大鼠皮层神经细胞。以原位ＤＮＡ 断端标记法检测培养神经细胞的凋亡，配以培养液中乳酸脱氢酶的检测，观察马桑内酯对培养皮层神经细胞的毒性作用，并与已知的神经毒剂海人酸作比较。结果显示，马桑内酯可诱导培养大鼠皮层神经细胞凋亡，而引起细胞坏死的作用不如海人酸明显，其对培养大鼠皮层神经细胞的神经毒作用以导致神经细胞凋亡为主。     

马桑内酯致痫大鼠海马内c—fos原癌基因表达及谷氨酸免疫反应的变化

用免疫细胞化学双重染色法对马桑内酯致痫大鼠齿状回及海马回ＣＡ３区内原癌基因表达、谷氨酸免疫反应的变化及其相互关系进行了研究。一侧侧脑室内注射马桑内酯诱发癫痫后，在双重免疫细胞化学染色的切片上，齿状回及海马回ＣＡ３区内均有３种不同类型的细胞：谷氨酸的单标细胞、Ｆｏｓ单标细胞和Ｆｏｓ／Ｇｌｕ双标细胞。癫痫发作后１ｈ，注射侧齿状回有大量Ｆｏｓ／Ｇｌｕ双标细胞，而海马回ＣＡ３区仅有散在的双标细胞；癫痫发作     

雌、孕激素对马桑内酯致痫大鼠行为及皮层、海马脑电图的影响

为了解卵巢激素在癫痫发作中所起的作用，本实验采用记录脑电图（ＥＥＧ）同时观察行为的方法，观察了雌二醇（Ｅ２）、孕酮（Ｐ）对马桑内酯（ＣＬ）致痫大鼠行为及皮层、海马ＥＥＧ的影响。结果显示：Ｅ２能缩短ＣＬ致痫大鼠痫性发作及痫波发放的潜伏期，增加痫波发放频率。与之相反，Ｐ具有明显的镇静催眠作用，并延长痫性发作及痫波发放潜伏期，减轻痫性发作程度，减少痫波发放次数。此为雌激素的致痫及孕激素的抗痫作用提供了行为及电生理学证据。本文还对雌、孕激素的基因和非基因作用机制进行了探讨。     

马桑内酯致痫大鼠海马内c－fos原癌基因表达及谷氨酸免疫反应的变化

用免疫细胞化学双重染色法对马桑内酯致痫大鼠齿状回及海马回ＣＡ３区内原癌基因表达、谷氨酸免疫反应的变化及其相互关系进行了研究。一侧侧脑室内注射马桑内酯诱发癫痫后，在双重免疫细胞化学染色的切片上，齿状回及海马回ＣＡ３区内均有３种不同类型的细胞：谷氨酸（Ｇｌｕ）单标细胞、Ｆｏｓ单标细胞和Ｆｏｓ／Ｇｌｕ双标细胞。癫痫发作后１ｈ，注射侧齿状回有大量Ｆｏｓ／Ｇｌｕ双标细胞，而海马回ＣＡ３区仅有散在的双标细胞；癫痫发作后１．５ｈ，海马回ＣＡ３区双标细胞数明显增多。Ｆｏｓ单标细胞数及谷氨酸免疫反应性与双标细胞数是平行的。根据以上结果，本文对马桑内酯致痫的机制进行了讨论。     

Influences of bilateral hippocampal lesions upon kindled amygdaloid convulsive seizure in rats

In this study, rat hippocampus was lesioned bilaterally after completion of amygdaloid kindling, to examine how hippocampus affects the kindling permanency. The ventral hippocampal lesions of the kindled rats inhibited reappearance of any kindled seizures. The other rats with the same lesions showed the regression of generalized convulsion. These results suggest that hippocampus, especially ventral parts of hippocampus, would have rather facilitatory or maintaining influence on the kindled neural circuits, relating to the catecholaminergic system in rat forebrain.     

The electrical basis for enhanced potassium secretion in rat distal colon during dietary potassium loading

Previous studies in rat distal colon provide evidence for an active absorptive process for potassium under basal conditions, and for active potassium secretion during chronic dietary potassium loading. The present studies were performed with conventional and potassium-selective microelectrodes to determine the electrical basis for the increase in transcellular (active) potassium secretion observed during potassium loading. Compared to control tissues, potassium loading resulted in a 5-fold increase in transepithelial voltage (V _T) and a 52% decrease in total resistance (R _T) in the distal colon. The rise inV _T was due to a decrease in apical membrane resistance and an increase in basolateral membrane voltage from –45±2 mV (cell interior negative) in control to –56±2 mV (P<0.001) in potassium loaded tissues. This difference in basolateral membrane voltage reflected in increase in intracellular potassium activity from 86±4 mM to 153±12 mM (P<0.001). In control tissues, the sequential mucosal addition of the sodium channel blocker amiloride (0.1 mM) and the potassium channel blocker tetraethylammonium chloride (TEA: 30 mM) produced no effect on the electrical measurements. However, in potassium loaded tissues, amiloride and TEA produced transepithelial changes consistent with inhibition of apical membrane conductances for sodium and potassium, respectively, reflected by increases in the resistance ratio, (ratio of apical to basolateral membrane resistances). These data indicate that the decrease in apical membrane resistance during potassium loading was caused by an increase in apical membrane conductance for both potassium and sodium.     

皮质发育障碍大鼠海马神经元钠通道功能的变化

目的： 探讨钠离子通道功能的改变在大脑皮质发育障碍性癫痫形成中的作用。方法：采用给孕鼠腹腔注射卡莫司汀的方法制作子代广泛型皮质发育障碍模型。急性分离大鼠海马CA1区神经元，运用全细胞膜片钳技术记录电压依赖性钠电流，并将模型组与对照组进行比较。结果：皮质发育障碍模型组CA1区神经元钠电流激活的电压依赖性向超极化方向偏移，失活的电压依赖性向去极化方向偏移，窗口钠电流较对照组明显增大（P<0.05）。模型组失活后的恢复时间常数较对照组明显缩短（P<0.05）。结论：电压依赖性钠通道功能的改变可能与皮质发育障碍癫痫易感性增高有关。     

蝎毒对马桑内酯所致癫（间）大鼠的作用

目的研究蝎毒素对癫（间）的作用,为新药的开发利用提供理论基础.方法采用整体马桑内酯大鼠癫（间）模型,侧脑室埋管给药,记录皮层脑电图.结果蝎毒素能延长马桑内酯所致癫（间）发作的潜伏期,降低发作程度,缩短发作时间.结论蝎毒素对马桑内酯所致的大鼠癫（间）具有对抗作用.     

Effect of sodium ions on penicillin-induced epileptiform activity in vitro

Summary Intra- and extracellular recordings were obtained from the CA1 region of guinea pig hippocampal slices maintained in vitro. We studied the effect of reducing the extracellular sodium concentration on penicillin-induced epileptiform responses.In control experiments, Tris and choline were assayed as sodium substitutes. Choline was found unsuitable, since it induced repetitive firing in the absence of any convulsant agent. Replacement of 50% of the extracellular sodium ([Na⁺]_o) with Tris reduced the amplitude of the presynaptic fiber volley, the field EPSP, and the population spike. Intracellular studies showed that when [Na⁺]_o was lowered, action-potential amplitudes were reversibly depressed by an amount close to that predicted by the Nernst relation.Orthodromically elicited epileptiform discharges, induced by penicillin, were reduced in a low-sodium medium when constant stimulus currents were employed. If orthodromic stimulus strengths in normal and low-sodium states were equated on the basis of the field-EPSP amplitude, no significant diminution of the depolarizing-wave component of the epileptiform response was observed. These results suggest that a synaptic component underlies penicillin-induced epileptiform discharges.Supported by grants from the Norwegian Research Council for Science and the Humanities and by NIH grants NS 11535 and NS 15772     

焦亚硫酸钠对大鼠海马CA1区神经元钠电流的影响

目的：探讨SO2 及其体内衍生物（亚硫酸盐和亚硫酸氢盐）对中枢神经元钠通道的影响。 方法: 采用全细胞膜片钳技术研究了焦亚硫酸钠（SMB）对大鼠海马CA1区神经元钠电流的影响及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及谷胱甘肽过氧化物酶(GPx)相应的保护作用。 结果： ① 焦亚硫酸钠可剂量依赖性地增大全细胞钠电流，剂量为2 μmol/L和20 μmol/L时，钠电流分别增大（22.36±3.28）% 和（65.05±5.75）%（n=10）。② 10　μmol/L的焦亚硫酸钠不影响钠电流的激活过程，却非常显著地影响其失活过程，使失活曲线显著右移，作用前后的半数失活电压分别为（-82.38±0.54）mV和（-69.39±0.41）mV (n=10, P<0.01), 但失活曲线的斜率因子未见改变。③ SOD(1×106 U/L)、CAT(2×106 U/L) 及GPx (1×104 U/L) 均可使SMB（10 μmol/L）增大的钠电流部分恢复。 结论： SMB增大钠电流并抑制其失活过程，从而影响神经细胞的兴奋性，这一效应可能与硫中心或氧中心自由基的损伤作用有关。     

Osmolality-induced changes in extracellular volume alter epileptiform bursts independent of chemical synapses in the rat: Importance of non-synaptic mechanisms in hippocampal epileptogenesis

The contribution of non-synaptic mechanisms to the seizure susceptibility of rat CA1 hippocampal pyramidal cells was examined in vitro by testing the effects of osmolality on synchronous neuronal activity, using solutions which blocked chemical synaptic transmission both pre- and post-synaptically. Decreases in osmolality, which shrink the extracellular volume, caused or enhanced epileptiform bursting. Increases in osmolality with membrane-impermeant solutes, which expand the extracellular volume, blocked or greatly reduced epileptiform discharges. Reductions in the extracellular volume, therefore, can enhance synchronization among CA1 hippocampal neurons through non-synaptic mechanisms. Since similar osmotic treatments are known to modify epileptiform discharges in several models of epilepsy, non-synaptic mechanisms are probably more important in hippocampal epileptogenesis than previously realized and may contribute to the high susceptibility of this brain region to epileptic seizures in animals and humans. These data also provide a possible explanation for the observation in humans that decreased plasma osmolality, which can be associated with a wide range of clinical syndromes, leads to seizures.