一氧化氮的释放对海马脑片CA1区痫样放电的影响

用自制的一氧化氮（ＮＯ）敏感电极－Ｎａｆｉｏｎ－壳聚糖合镍修饰铂电极（Ｎａｆｉｏｎ－ＣＴＳ（Ｎｉ）－Ｐｔ）连续测定了青霉素致痫海马脑片ＣＡ１区锥体层神经元ＮＯ的释放,并同时观察了ＮＯ合酶抑制剂７－ｎｉｔｒｏ－ｉｎｄａｚｏｌｅ（７－ＮＩ）及Ｎ＾ω－ｎｉｔｒｏ－Ｌ－ａｒｇｉｎｉｎｅ（Ｌ－ＮＮＡ）对诱发痫波及ＮＯ释放量的影响。研究观察到：（１）在青霉素致痫脑片模型上,诱发的痫波随青霉素浓度的增加而增多,     

电针对实验性癫痫发作的影响：脑电的功率谱分析

以电惊厥和青霉素致痫作为实验性癲痫的动物模型。采用脑电的计算机功率谱分析技术,研究了电针作用于发作过程中脑电各频段功率百分比的变化。在安静的大鼠,脑电以δ和θ频段为主,其功率主峰在δ频段。青霉素致痫和电惊厥使δ频段功率百分比下降,α和β频段功率百分比增加,主功率频段右移,总功率亦大大增强。本实验采用的电针对背景脑电活动没有明显影响。而电针加电惊厥或青霉素致痫,δ频段功率百分比复又增加,α和β频段功率百分比则下降,主功率频段又回到δ频段,总功率也显著减少。压缩功率谱阵图直观地显示了这种变化。结果提示,电针可使大鼠脑电出现同步化趋势,可能是加强了脑的抑制过程,从而抑制了癲痫发作的。     

川芎嗪改善癫痫大鼠水迷宫成绩和海马PS幅度

目的：观察川芎嗪对青霉素致痫大鼠学习记忆的影响。方法：造模后,腹腔注射川芎嗪,通过水迷宫实验和在体记录海马CA1区群峰电位（PS）以观测大鼠学习记忆的变化。结果：①癫痫发作使大鼠入水找到终点的时间延长 ②癫痫发作后海马CA1区PS幅度降低 ③注射川芎嗪后癫痫大鼠入水找到终点的时间缩短 ④注射川芎嗪后癫痫大鼠海马CA1区PS幅度升高。结论：川芎嗪可能对青霉素致痫大鼠学习记忆的损伤有改善作用。     

生长抑素对实验性癫痫大鼠海马CA1区的作用

在大鼠海马ＣＡ１区微量注射０．０３－０．３ｎｍｏｌ生长抑素（ｓｏｍａｔｏｓｔａｔｉｎ,ＳＳ）后,皮层脑电出现单个或成串的棘尖波,平均脑电总功率著升高,并且在一定范围内（０．００６－０．１５ｎｍｏｌ）具有剂量依赖性。在海马ＣＡ１微量注射０．０３－０．３ｎｍｏｌＳＳ可诱发大鼠表现出痫样行为,并可加重红藻氨酸诱导的大鼠痫样活动。在９５个大鼠海马脑片上细胞外记录ＳＳ对ＣＡ１区青霉素诱导的１１４个痫样放电单     

实验性癫痫时海马内一氧化氮合酶的变化及其与谷氨酸受体的关系

应用免疫组织化学方法观察了青霉素致痫时海马内神经元型一氧化氮合酶（ｎＮＯＳ）表达的时程变化及海马内微量注射ＮＭＤＡ受体拮抗剂ＭＫ－８０１（５－ｍｅｔｈｙｌ－１０,１１－ｄｉｈｙｄｒｏ－５Ｈ－ｄｉｂｅｎｚｏ［ａ,ｄ］ｃｙｃｌｏｈｅｐｔａｎ－５,１０－ｉｍｉｎｅｍａｌｅａｔｅ）和非ＮＭＤＡ受体拮抗剂ＤＮＱＸ（６,７－ｄｉｎｉｔｒｏｑｕｉｎｏｘａｌｉｎｅ－２,３－ｄｉｏｎｅ）对大鼠海马内ｎＮＯＳ表达的影     

功率谱熵在痫性发作大鼠脑电检测中的应用研究

目的:研究功率谱熵在痫性发作大鼠脑电检测中的应用。方法:采用青霉素在大鼠海马微注射制备急性痫性发作模型,以深部电极记录大鼠原始脑电信号,将24只SD大鼠随机分成四组,即正常组(A),对照组(B),单电极组(C),多电极组(D)。C、D组大鼠经致痫后观察未发作期、发作前期、发作期和发作后期四期脑电信号的变化,运用谱熵对四期脑电信号进行分析,并与A、B组进行对比。结果:C组和D组脑电功率谱熵显示两组发作期与未发作期、发作前期、发作后期比较有显著差异(P0.05),发作期明显低于其它各期;未发作期和发作前期相比有明显差异(P0.05),发作前期较未发作期降低;将D组大鼠海马致痫灶(a)及其同侧附近(b)、对侧(c)三点发作各期脑电功率谱熵进行对比分析,发作前期和发作期a、b、c三点比较有明显差异(P0.05),a点最低,c点的功率谱熵值最高。结论:功率谱熵可以预报痫性发作并可对癫痫病灶的定位提供一定的帮助。     

IL—1β,IL—lra对戊四氮致痫大鼠行为及皮层,海马脑电的 …

目的：了解白细胞介素１β（ＩＬ－１β）在癫痫发作中的作用。方法：采用记录脑图（ＥＥＧ）同时观察行为的方法,观察ＩＬ－１β和ＩＬ－１受体拮抗剂（ＩＬ－１ｒａ）测脑室注射对戊四氮（ＰＴＺ）致痫大鼠和皮层、海马ＥＥＧ的影响。结果：ＩＬ－１β能明显缩短ＰＴＺ致大鼠急性惊厥发作及痫波发放的潜伏期,增加痫波的发放频率。ＩＬ－１ｒａ能减少急性惊厥痫波放频率,对急性惊厥发主痫波发放的潜伏期和惊厥发作强度无明显影响     

柴胡对癫痫模型电活动的调制

目的 :研究柴胡对癫痫发作的影响。方法 :以家兔和大鼠为实验对象 ,用毛果芸香碱致痫 ,采用脑电图和细胞外玻璃微电极记录技术 ,观察柴胡对癫痫模型大脑皮层放电及海马脑片场电位的影响。结果 :腹腔注射柴胡后可使癫痫发作次数及发作持续时间显著减少 ,发作间隔时间显著延长 ,(P <0 .0 5 ) ,脑片旁滴注柴胡后使致痫大鼠海马脑片诱发场电位幅度平均降低 2 0 .4 1% ,恢复时间平均为 6 .86min ,(P <0 .0 1)。结论 :柴胡注射液能明显抑制癫痫模型电活动 ,提示柴胡具有抗痫作用     

点燃大鼠海马脑片CA1区电活动的变化

重复间隔地给予阈下致惊厥量的电或化学刺激,能使动物出现进行性增强的痫性活动,最后导致动物出现癫痫大发作而点燃(kindling)。点燃作为一种癫痫模型,较好地模拟了人类癫痫的渐进性发展过程和长期反复的自限性发作形式。Racine用电刺激杏仁核点燃动物时,在脑内不同部位放置记录电极以观察后发放(afterdischarge)的变化,发现点燃能使动物的     

癫痫模型及致痫机制的探讨

青霉素致痫所引起的阵发性除极转变有突触活动增强及自发放电两种学说。在体脑组织癫痫发作有周围抑制、高度同步化及回放等特点。全身性青霉素癫痫发作与失神小发作相似,其棘慢波的产生与丘脑有关。点燃效应作为慢性癫痫模型受到重视,其中产生机制有不同的看法。一些脑内递质如γ-氨基丁酸、去甲肾上腺素、5-羟色胺、阿片样物质及有关的脑区在致病中有一定的作用。     

Fenfluramine-induced serotonergic neurotoxicity in mice: lack of neuroprotection by inhibition/ablation of nNOS

Previous studies have implicated a role for nitric oxide (NO) and peroxynitrite in methamphetamine-induced dopaminergic neurotoxicity. The present study was undertaken to investigate whether NO is involved in serotonergic neurotoxicity caused by fenfluramine. In the first experiment, the effect of the neuronal nitric oxide synthase (nNOS) inhibitor 7-nitroindazole (7-NI; 25 mg/kg x 4) on fenfluramine (25 mg/kg x 4)-induced serotonergic neurotoxicity in Swiss Webster mice was investigated. In the second experiment, the effect of fenfluramine (25 mg/kg x 4) on nNOS (-/-) and wild-type (WT) mice was investigated. Fenfluramine induced hypothermia in all three mouse strains, and 7-NI had no thermoregulatory effect. Selective depletion of 5-HT and 5-HT transporter binding sites in the striatum, frontal cortex and hippocampus in all three mouse strains was observed, with no evidence of dopaminergic neurotoxicity. In the first experiment, 7-NI did not attenuate serotonergic neurotoxicity in Swiss Webster mice. In the second experiment, nNOS(-/-) and WT mice were equally sensitive to serotonergic neurotoxicity. These findings suggest that NO and peroxynitrite do not mediate fenfluramine-induced serotonergic neurotoxicity, and that NO is a selective mediator of amphetamines-induced dopaminergic neurotoxicity.     

Inhibition of neuronal nitric oxide synthase by 7-nitroindazole attenuates acute lung injury in an ovine model

Nitric oxide (NO) has been shown to play a major role in acute lung injury (ALI) after smoke inhalation. In the present study, we developed an ovine sepsis model, created by exposing sheep to smoke inhalation followed by instillation of bacteria into the airway, that mimics human sepsis and pneumonia. We hypothesized that the inhibition of neuronal NO synthase (nNOS) might be beneficial in treating ALI associated with this model. Female sheep (n = 26) were surgically prepared for the study and given a tracheostomy. This was followed by insufflation of 48 breaths of cotton smoke (40 degrees C) into the airway of each animal and subsequent instillation of live Pseudomonas aeruginosa [5 x 10(11) colony forming units (CFU)] into each sheep's lung. All sheep were mechanically ventilated using 100% O2. Continuous infusion of 7-nitroindazole (7-NI), an nNOS inhibitor, NG-monomethyl-l-arginine (l-NMMA), a nonspecific NOS inhibitor, or aminoguanidine (AG), an inducible NOS inhibitor, was started 1 h after insult. The administration of 7-NI improved pulmonary gas exchange (PaO2/FiO2; where PaO2 is arterial PO2 and FiO2 is fractional inspired oxygen concentration) and pulmonary shunt fraction and attenuated the increase in lung wet-to-dry weight ratio seen in the nontreated sheep. Histologically, 7-NI prevented airway obstruction. The increase in airway blood flow after injury in the nontreated group was significantly inhibited by 7-NI. The increase in plasma concentration of nitrate and nitrite (NOx) was inhibited by 7-NI as well. Posttreatment with l-NMMA improved the pulmonary gas exchange, but AG did not. The results of the present study show that nNOS may be involved in the pathogenesis of ALI after smoke inhalation injury followed by bacterial instillation in the airway.     

电针对去卵巢大鼠学习记忆能力及海马神经元型一氧化氮合酶mRNA表达的影响

目的研究电针对去卵巢大鼠学习记忆能力及海马神经元型一氧化氮合酶（nNOS）mRNA表达的影响。方法采用卵巢切除大鼠模型,造成低雌激素记忆障碍,去势2周后进行电针刺激,连续治疗3个月。Morris水迷宫测试空间学习记忆能力,酶联免疫吸附分析（ELISA）检测血清雌二醇（E2）浓度,实时荧光定量PCR检测检测nNOSmRNA的相对表达量。结果与假手术组比较,模型组大鼠逃避潜伏期时间明显延长,跨越平台次数明显减少,血清E2浓度和海马nNOSmR—NA表达显著降低（P〈O．01）;与模型组比较,电针组和假电针组治疗后逃避潜伏期缩短,跨越平台次数增加,血清E2浓度和海马nNOSmRNA表达均显著升高,电针组升高更明显（P〈O．01）。结论电针能够提高去卵巢大鼠学习记忆能力,其机制可能与升高体内雌激素浓度上调海马nNOSmRNA的表达有关。     

Effect of chronic nNOS inhibition on blood pressure, vasoactivity, and arterial wall structure in Wistar rats

While the unequivocal pattern of endothelial nitric oxide (NO) synthase (eNOS) inhibition in cardiovascular control has been recognised, the role of NO produced by neuronal NOS (nNOS) remains unclear. The purpose of the present study was to describe the cardiovascular effects of NO production interference by inhibition of nNOS with 7-nitroindazole (7-NI). Wistar rats (10 weeks old) were used: control and experimental rats were administered 7-NI 10 mg/kg b.w./day in drinking water for 6 weeks. Systolic blood pressure (BP) was measured by the tail-cuff plethysmographic method. Isolated thoracic aortas (TAs) were used to study vasomotor activity of the conduit artery in vitro. The BP response of anaesthetised animals was used to follow the cardiovascular-integrated response in vivo. Geometry of the TA was measured after perfusion fixation (120 mm Hg) by light microscopy. Expression of eNOS was measured in the TA by immunoblot analysis. Although 6 weeks of nNOS inhibition did not alter systolic BP, the heart/body weight ratio was decreased. Relaxation of the TA in response to acetylcholine (10⁻⁹–10⁻⁵ mol/L) was moderately inhibited. However, no difference in the BP hypotensive response after acetylcholine (0.1, 1, 10 μg) was observed. The contraction of TA in response to noradrenaline (10⁻¹⁰–10⁻⁵ mol/L), and the BP pressor response to noradrenaline (0.1, 1 μg) was attenuated. The inner diameter of the TA was increased, and the wall thickness, wall cross-sectional area, and wall thickness/inner diameter ratio were decreased. The expression of eNOS in the TA was increased. In summary, cardiac and TA wall hypotrophy, underlined by decreased contractile efficiency, were observed. The results suggested that two constitutive forms of NOS (nNOS, eNOS) likely participate in regulation of cardiovascular tone by different mechanisms.     

Inhibition of nNOS reduces ischemic cell death through down-regulating calpain and caspase-3 after experimental stroke

In vitro nitric oxide (NO) regulates calpain and caspase-3 activation, and in vivo neuronal nitric oxide synthase (nNOS), calpain and caspase-3 participate in the ischemic brain injury. Our objective was to investigate whether nNOS was involved in the ischemic brain injury through activating calpain and caspase-3 during experimental stroke. Rats received 1-h ischemia by intraluminant filament, and then reperfused for 23 h (R 23 h). nNOS inhibitor 7-nitroindozale (7-NI, 50 mg/kg) was administrated intraperitoneally 5 min before ischemia. Our data showed that treatment with 7-NI markedly reduced neurological deficits, the brain swelling, and the infarct volume at R 23 h. Enzyme studies revealed significant suppression of the activities of m-calpain and caspase-3 in penumbra and core, and the activities of μ-calpain in penumbra, but not in core, in 7-NI-treated rats versus vehicle-treated rats. Western blot analysis demonstrated that 7-NI markedly increased the levels of MAP-2 and spectrin in penumbra and core compared with vehicle-treated rats. Histopathological studies displayed that 7-NI significantly reduced the necrotic cell death in penumbra and core, and apoptotic cell death in penumbra, but not in core. These data demonstrate the involvement of NO produced by nNOS in the ischemic neuronal injury through affecting the activation of calpain and caspase-3 in penumbra and core after experimental stroke, which provides a new perspective on possible mechanisms of action of nNOS inhibition in cerebral ischemia.     

Extremely low-frequency magnetic fields modulate nitric oxide signaling in rat brain

Our previous study has shown that an extremely low‐frequency magnetic field (ELF‐MF) induces nitric oxide (NO) synthesis by Ca²⁺‐dependent NO synthase (NOS) in rat brain. The present study was designed to confirm that ELF‐MF affects neuronal NOS (nNOS) in several brain regions and to investigate the correlation between NO and nNOS activation. The exposure of rats to a 2 mT, 60 Hz ELF‐MF for 5 days resulted in increases of NO levels in parallel with cGMP elevations in the cerebral cortex, striatum, and hippocampus. Cresyl violet staining and electron microscopic evaluation revealed that there were no significant differences in the morphology and number of neurons in the cerebral cortex, striatum, and hippocampus. Differently, the numbers of nNOS‐immunoreactive (IR) neurons were significantly increased in those cerebral areas in ELF‐MF‐exposed rats. These data suggest that the increase in NO could be due to the increased expression and activation of nNOS in cells. Based on NO signaling in physiological and pathological states, ELF‐MF created by electric power systems may induce various physiological changes in modern life. Bioelectromagnetics 33:568–574, 2012. © 2012 Wiley Periodicals, Inc.     

Involvement of nitric oxide in pentylenetetrazole-induced kindling in rats

We investigated the role of nitric oxide (NO) and brain-derived neurotrophic factor (BDNF) in the pentylenetetrazole (PTZ)-induced kindling in rats. Seizures were induced by single administration of PTZ, which was associated with an increase in levels of NO metabolites (NOx) in the hippocampus. Pretreatment with a neuronal NO synthase inhibitor, 7-nitroindazole (7-NI), diminished the PTZ-induced increase in NOx levels without affecting the seizure intensity. Repeated administration of PTZ produced a gradual increase in the seizure intensity, leading to the development of kindling. In the kindled rats, PTZ at a dose of 40 mg/kg increased NOx levels in the hippocampus, whereas it had no effect in control animals. Cotreatment of 7-NI with PTZ blocked the development of kindling and attenuated the PTZ-induced increase in NOx levels. A significant increase in BDNF levels was observed in the hippocampus of the kindled rats, which returned to the control levels following seizures induced by PTZ. 7-NI reduced the hippocampal BDNF levels in control rats and suppressed the increase of BDNF levels in the kindled rats. Our findings suggest that NO plays a role in the development of PTZ-induced kindling and that BDNF may contribute to the NO-dependent plastic changes in neuronal excitability.     

Nitric oxide synthase and cGMP-mediated stimulation of renin secretion

The interaction between nitric oxide (NO) and renin is controversial. cAMP is a stimulating messenger for renin, which is degraded by phosphodiesterase (PDE)-3. PDE-3 is inhibited by cGMP, whereas PDE-5 degrades cGMP. We hypothesized that if endogenous cGMP was increased by inhibiting PDE-5, it could inhibit PDE-3, increasing endogenous cAMP, and thereby stimulate renin. We used the selective PDE-5 inhibitor zaprinast at 20 mg/kg body wt ip, which we determined would not change blood pressure (BP) or renal blood flow (RBF). In thiobutabarbital (Inactin)-anesthetized rats, renin secretion rate (RSR) was determined before and 75 min after administration of zaprinast or vehicle. Zaprinast increased cGMP excretion from 12.75 +/- 1.57 to 18.67 +/- 1.87 pmol/min (P < 0.003), whereas vehicle had no effect. Zaprinast increased RSR sixfold (from 2.95 +/- 1.74 to 17.62 +/- 5.46 ng ANG I. h(-1) x min(-1), P < 0.024), while vehicle had no effect (from 4.08 +/- 2.02 to 3.87 +/- 1.53 ng ANG I x h(-1) x min(-1)). There were no changes in BP or RBF. We then tested whether the increase in cGMP could be partially due to the activity of the neuronal isoform of NO synthase (nNOS). Pretreatment with the nNOS inhibitor 7-nitroindazole (7-NI; 50 mg/kg body wt) did not change BP or RBF but attenuated the renin-stimulating effect of zaprinast by 40% compared with vehicle. In 7-NI-treated animals, zaprinast-stimulated cGMP excretion was attenuated by 48%, from 9.17 +/- 1.85 to 13.60 +/- 2.15 pmol/min, compared with an increase from 10.94 +/- 1.90 to 26.38 +/- 3.61 pmol/min with zaprinast without 7-NI (P < 0.04). This suggests that changes in endogenous cGMP production at levels not associated with renal hemodynamic changes are involved in a renin-stimulatory pathway. One source of this cGMP may be nNOS generation of NO in the kidney.