大鼠实验性乙醇胃粘膜损伤中一氧化氮合成酶和内皮素合量 …

目的：探讨一氧化氮和内皮素在急性乙醇胃膜损伤中的作用及其相互关系。方法：采用大鼠乙醇胃粘膜损伤模型,测定其胃粘膜内一氧化合成酶（ＮＯＳ）和内皮素（ＥＴ）含量并观察其胃膜病理变化。结果：随着乙醇作用时间延长和胃粘膜损伤和加重,胃粘膜内ＥＴ含显著上升,而ＮＯＳ的含量显著下降,两者呈负相产在。结论：胃粘膜内ＥＴ释放增加和ＮＯＳ活性下降参与了急性乙醇胃粘膜损伤的病理生理过程。     

乙醇对胃粘膜的损伤及牛磺酸的保护作用

为了探讨乙醇性胃粘膜损伤和牛磺酸对其保护作用的机制,将４０只ＳＤ大鼠分为对照组、乙醇损伤组和牛磺酸保护组,观察其胃粘膜中内皮素（ＥＴ）、一氧化氮合成酶（ＮＯＳ）、生长抑素（ＳＳ）和血管活性肠肽（ＶＩＰ）的变化。结果如下：（１）随着乙醇作用时间延长、粘膜的损伤加重,胃粘膜内ＥＴ含量显著上升,而ＮＯＳ、ＳＳ和ＶＩＰ含量显著下降;（２）牛磺酸可显著减轻乙醇性胃粘膜损伤,抑制ＥＴ释放,增加ＮＯＳ活性和ＳＳ、ＶＩＰ的含量。上述结果表示,ＥＴ、ＮＯＳ、ＳＳ和ＶＩＰ的变化参与了乙醇性胃粘膜损伤的病理生理过程;牛磺酸对乙醇性胃粘膜损伤具有保护作用,可能与其调节胃粘膜内ＥＴ、ＮＯＳ、ＳＳ和ＶＩＰ的释放与活性有关。     

应激状态下NO的胃粘膜保护作用及其与壁细胞泌酸的关系

目的:探讨应激状态下一氧化氮(NO)的胃粘膜保护作用及其与壁细胞泌酸的关系.方法:采用水浸-束缚应激(WRS)方法制备应激性溃疡(SU)动物模型,检测胃粘膜溃疡指数(UI)、胃粘膜NO含量和壁细胞H ,K -ATPase活性,观察L-硝基精氨酸甲酯(L-NAME)和L-精氨酸(L-Arg)对应激后大鼠壁细胞H ,K -ATPase活性及胃粘膜损伤的影响.结果:L-NAME(20 mg·kg-1)可使胃粘膜NO含量减少(P＜0.01),壁细胞H ,K -AT-Pase活性增加(P＜0.05),并加重应激所致的胃粘膜损伤;L-Arg(300 mg·kg-1)则使胃粘膜NO含量增加(P＜0.01),壁细胞H ,K -ATPase活性下降(P＜0.05),减轻应激所致胃粘膜损伤.结论:NO对应激状态下大鼠胃粘膜具有保护作用,其机制与抑制壁细胞H ,K -ATPase活性有关.     

Aβ325～35诱导大鼠记忆减退与星形胶质细胞及NOS阳性细胞变化

目的　探讨Aβ2 5～ 3 5诱导模拟人类Alzheimer‘s病 (AD)的大鼠病理模型中星形胶质细胞变化与一氧化氮合酶神经元损伤引起的老年性记忆减退之间的关系。方法　双侧海马内注射 β-淀粉样多肽 2 5～ 3 5片段 (Aβ2 5～ 3 5 )制作大鼠AD模型 ,注射一周后采用NOS组化染色、GFAP免疫组化染色及NOS组化和GFAP双重染色分析大鼠海马GFAP与NOS的表达。结果　海马内注射Aβ2 5～ 3 5后出现海马星形胶质细胞增生、肥大、数目明显多于对照组 (P <0 0 5 ) ,并出现一氧化氮阳性星形胶质细胞 ;海马一氧化氮神经元数量较对照组显著减少 (P <0 0 5 )。结论　AD模型大鼠学习记忆功能低下与Aβ神经毒性导致NOS阳性神经元损伤、死亡直接相关 ,反应性星形胶质细胞参与Aβ导致NOS神经元细胞毒性损伤作用 ,间接导致学习记忆能力减退     

巯基参与胃粘膜防御机制

本工作研究了胃粘膜非蛋白质巯基物质(NPSH)在粘膜防御功能中的作用。结果表明,酸性乙醇灌胃或冷冻加束缚应激引起大鼠胃粘膜 NPSH 含量显著下降;补充含-SH 的化合物半胱胺或还原型谷胱甘肽可防止酸性乙醇引起的胃粘膜损伤;在酸性乙醇灌胃或应激后,胃粘膜谷胱甘肽还原酶活性明显降低,并与 NPSH 含量的下降在时间上一致;丙二醛含量在酸性乙醇灌胃后显著升高,自由基清除剂二甲亚砜可减轻胃粘膜损伤。上述结果提示,胃粘膜NPSH 可能通过对自由基的清除作用参与粘膜的局部防御机制;谷胱甘肽还原酶活性下降和自由基生成增加所导致的粘膜 NPSH 含量下降可能是损伤发生过程的重要环节。     

尤瑞克林注射液对急性脑梗塞患者血浆ET及CGRP的影响研究

目的:研究尤瑞克林注射液对急性脑梗塞惠者血浆内皮素(ET)及降钙素基因相关肽(CGRP)影响.方法:急性脑梗塞患者48例,随机分为治疗组及对照组(常规治疗).治疗组在常规治疗的基础上加用尤瑞克林注射液.用放射免疫法检测患者治疗第1天、第7天血浆中内皮素及降钙素基因相关肽的含量,并对两组患者治疗前后进行美国国立卫生院神经功能缺损评分.结果:治疗组血浆ET水平及NIHSS均较对照组有明显下降(P＜0.05),CGRP升高较对照组明显(P＜0.05).结论:尤瑞克林能显著降低急性脑梗塞患者血浆ET及升高CGRP的含量,改善血管内皮功能,降低神经功能缺损程度.     

正交设计筛选三七皂苷单体最佳组合及对血管内皮保护作用评价

目的:利用正交实验筛选出三七皂苷单体最佳组合并观察其对氧化低密度脂蛋白(Ox-LDL)损伤血管内皮细胞的保护作用。方法:体外培养人脐静脉内皮细胞(HUVEC),加入100mg.L-1OX-LDL诱导单核-内皮细胞黏附,蛋白染料法测定黏附值,通过正交试验设计筛选出三七皂苷单体最佳组合;比色法检测乳酸脱氢酶(LDH)的释放量;硝酸还原法和放射免疫法分别测定HU-VEC培养上清液中一氧化氮(NO)、内皮素(ET)含量。结果:获得最佳PNS单体组合为:Rg1:Rb1:R1为1:10:1(Rg110-5mol/L、Rb110-4mol/L、R110-5mol/L),最佳单体组合显著降低LDH及ET水平,提高NO含量(P<0.01)。结论:由正交实验设计筛选出的最佳单体组合对OX-LDL所致的血管内皮细胞损伤有显著的保护作用。     

天门冬水提液及其纳米中药对衰老模型小鼠NOS、NO、LPF的影响

目的:探讨中药天门冬及其纳米化后对D-半乳糖衰老模型小鼠血清和肝的抗氧化作用.方法:采用D-半乳糖致衰老小鼠分别ig相同剂量的天门冬水提液及其纳米中药15 d,测定衰老小鼠血清中一氧化氮合酶(NOS)的活性,一氧化氮(NO)含量及肝组织中脂褐素(LP下)的含量.结果:天门冬水提波及其纳米中药均能显著增强小鼠血清中NOS的活性(P＜0.01),提高N0含量(P＜0.05),降低LPF含量(P＜0.05),且纳米中药的药效强于天门冬水提液的药效(P＜0.05).结论:天门冬水提液及其纳米中药均有抗氧化作用,且纳米中药比水提液药效更好.     

牛磺酸对失血性休克复苏家兔血浆和心肌NOS活性影响

目的:探讨牛磺酸对失血性休克复苏后血浆和心肌一氧化氮合酶(NOS)活性、一氧化氮(NO)含量变化的影响.方法:新西兰种兔24只随机分为3组(n=8):对照组、休克组、牛磺酸治疗组.采用失血性休克复苏动物模型.连续观察休克前、休克1.5 h、复苏后1 h、2 h、3 h血浆一氧化氮合酶(NOS)活性、一氧化氮代谢产物(NO-2/NO-3)含量、乳酸脱氢酶(LDH)活性的动态变化.测定复苏后3 h心肌一氧化氮合酶(NOS)活性、一氧化氮代谢产物(NO-2/NO-3)含量的变化,并常规留取心肌标本观察形态学改变.结果:①休克组复苏后各时限血浆NOS活性、NO-2/NO-3含量、LDH活性显著高于休克前及休克1.5 h;②休克组复苏后3 h心肌NOS活性、NO-2/NO-3含量显著高于对照组,心肌出现明显水肿和脂肪变性;③牛磺酸(40 mg·kg-1 iv)可显著缓解上述变化.结论:失血性休克复苏后NOS的激活和NO的大量释放,可能介导了休克复苏所致心肌损伤,牛磺酸可减少NO的生成使心肌损伤减轻.     

重复肢体缺血对健康受试者全身血浆NO及NOS含量的影响

目的:研究人远程缺血预适应模型--重复肢体缺血(RLI)对健康成人血浆一氧化氮(NO)和不同类型NO合酶(NOS)含量的影响.方法:血计袖带压迫非优势侧肱动脉(压力200 mmHg, 缺血/放松 5 min/5 min,共5次),持续监测生理指标,记录主观感受.在Pre、Post-0h、Post-4 h和Post-24 h抽取压迫对侧肘静脉血.应用Griess法检测NO含量,用化学法检测NOS含量.结果:受试者血压、心率在正常范围内波动.压迫侧肢体的不适感随着压迫次数逐渐减轻.血浆NO和iNOS在Post-0 h、Post-4 h和Post-24 h较Pre有显著提高(P＜0.05).总NOS在Post-0 h和Post-4 h较Pre有显著提高(P＜0.05).而cNOS在RLI后各时间点与Pre比较无统计学差异(P＞0.05).结论:RLI是安全,可耐受的方法,其可诱导健康人血浆NO及总NOS、iNOS含量升高,并至少维持4～24 h.     

Cholecystokinin secretagogue-induced gastroprotection: role of nitric oxide and blood flow

This study was done to examine the role of CCK in gastric mucosal defense and to assess the gastroprotective roles of nitric oxide and blood flow. In rats, the CCK secretagogues oleate and soybean trypsin inhibitor augmented gastric mucosal blood flow and prevented gastric injury from luminal irritants. Type A CCK receptor blockade negated CCK secretagogue-induced gastroprotection and exacerbated gastric injury from bile and ethanol but did not block adaptive cytoprotection. CCK secretagogue-induced gastroprotection and hyperemia were negated by nonselective nitric oxide synthase (NOS) inhibition (N(G)-nitro-L-arginine methyl ester) but not by selective inducible NOS inhibition (aminoguanidine). Gastric mucosal calcium-dependent NOS activity, but not calcium-independent NOS activity, was increased following CCK and CCK secretagogues. The release of endogenous CCK plays a role in the intrinsic gastric mucosal defense system against injury from luminal irritants. The protective mechanism appears to involve increased production of nitric oxide from primarily the constitutive isoforms of NOS and a resultant increase in blood flow.     

Role of endogenous nitric oxide synthase inhibitor in gastric mucosal injury

To explore the role of the endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) in gastric mucosal injury, 3 models of gastric mucosal injury induced by ethanol, indomethacin, or cold stress were used in rats. The cultured human gastric mucosal epithelial cell line GES-1 infected by Helicobacter pylori (Hp) was selected to mimic human gastric mucosal injury. Gastric mucosal ulcer index (UI), levels of ADMA and NO, and activity of dimethylarginine dimethylaminohydrolase (DDAH) were determined in the mucosal injury models; in Hp-infected or ADMA-treated GES-1 cells, levels of ADMA, NO, and TNF-alpha and activity of DDAH were measured. The results showed that UI and levels of ADMA were markedly increased and accompanied by significantly decreased DDAH activity in the mucosal injury models. Incubation of GES-1 cells with Hp increased levels of TNF-alpha and ADMA and decreased activity of DDAH. Administration of ADMA also increased levels of TNF-alpha. The results suggest that ADMA plays an important role in facilitating gastric mucosal injury, an effect which is associated with inhibiting NO synthesis and inducing inflammatory reaction.     

Significance of ERK nitration in portal hypertensive gastropathy and its therapeutic implications

Portal hypertensive (PHT) gastric mucosa increases susceptibility to injury and delayed mucosal healing. It is possible that nitration of ERK by peroxynitrite might alter MAPK (ERK) signaling in PHT gastric mucosa, leading to delayed mucosal healing, since excessive nitric oxide production is implicated in PHT gastric mucosa and MAPK (ERK) signaling induces cell proliferation and leads to gastric mucosal healing in response to injury. Portal hypertension was produced by staged portal vein ligation, and sham-operation (SO) rats served as controls. Lipid peroxide (LPO) and nitrotyrosine increased significantly in PHT gastric mucosa compared with SO rats. ERK activation was impaired in PHT gastric mucosa in response to ethanol injury, whereas no significant difference in the phosphorylation of MEK, an upstream molecule of ERK, was seen between the two groups. The nitration of ERK by peroxynitrite, as detected by the coimmunoprecipitation of ERK and nitrotyrosine, was significantly enhanced in PHT gastric mucosa. Administration of rebamipide, a gastroprotective drug that acts as an oxygen-derived free radical scavenger, significantly decreased LPO and nitrotyrosine as well as the nitration of ERK by peroxynitrite in PHT gastric mucosa, therefore normalizing ERK activation and restoring the gastric mucosal healing response to ethanol injury. Enhanced nitration of ERK by peroxynitrite is involved in the impaired MAPK (ERK) signaling in PHT gastric mucosa. These findings demonstrate a new molecular mechanism in which PHT gastric mucosa is predisposed to injury and impaired healing.     

Caffeine does not modulate nutritive blood flow to rat gastric submucosa--a microdialysis study

Background and Aims: Coffee irritates the gastric mucosa disrupting its barrier and increasing the risk of peptic ulcers. However, caffeine's contribution to these effects has not yet been elucidated. In this study we looked at the local effect of caffeine on the microcirculation and nitric oxide production in rats together with systemic marker of oxidative stress malondialdehyde as possible mechanisms whereby caffeine might participate in mucosal barrier impairment. Materials and Methods: Four groups of rats were anesthetized and administered as a bolus four different intraperitoneal doses of caffeine (0, 1, 10 and 50 mg kg(-1) b.wt.). The gastric submucosal microcirculation and nitric oxide production were then recorded for 2.5 hours by in situ microdialysis using the flow marker ethanol. At the completion of the experiments, plasma caffeine and malondialdehyde levels as well as morphological mucosal injury were determined. Results: There were no major differences in the macro- or microscopic pictures of the mucosa among the groups. Local microcirculatory (ethanol out/in ratio) and nitric oxide monitoring failed to demonstrate statistically significant changes as did measurement of plasma malondialdehyde in response to caffeine injections. Conclusions: Caffeine per se seems unlikely to contribute to the gastric mucosal barrier injury associated with coffee consumption by alterations in nutritive blood flow, nitric oxide production or aggravation of systemic oxidative stress. This information is relevant for better understanding of the mechanisms involved in caffeine-mediated influences on gastric physiology in relation to the irritant effects of coffee.     

一氧化氮/内皮素在大鼠胃粘膜损伤中的作用及电针的调整效应

用酒精灌胃引起大鼠胃粘膜损伤模型,观察内皮衍生因子（ＮＯ／ＥＴ）的含量变化和电针对胃粘膜损伤调整作用,结果发现：酒精灌胃后,胃粘膜血流量（ＧＭＢＦ）、跨壁电位差,血ＮＯ含量降低（Ｐ〈０．０１）,血浆ＥＴ含量和胃粘膜损伤指数（ＬＩ）增高（Ｐ〈０．０１）。Ｌ－精氨酸（Ｌ－Ａｒｇ）或硝普钠（ＳＮＰ）灌注预处理后（ｉｖ）,ＮＯ含量和ＧＭＢＦ明显升高（Ｐ〈０．０１）,ＥＴ含量和ＬＩ指数下降（Ｐ〈０．０１）。     

Protective effect of L-citrulline against acute gastric mucosal lesions induced by ischemia-reperfusion in rats

The present study investigated the protective effect of L-citrulline on gastric mucosal injury induced by ischemia-reperfusion (IR) in rats. Under anesthesia, the celiac artery was clamped for 30 min, and then the clamp was removed for 60 min reperfusion. Sixty minutes before ischemia, L-citrulline was administered intragastrically at doses of 300, 600, and 900 mg/kg. After the experiment, the stomachs were removed for biochemical and histological examinations. Pretreatment with L-citrulline (300, 600, and 900 mg/kg) significantly ameliorated the gastric damage caused by IR. Moreover, L-citrulline prevented the production of lipid peroxidation and inhibited the increase of myeloperoxidase activity. The elevation in total nitric oxide synthase (NOS) activity, inducible NOS activity, and inducible NOS protein expression as well as the decrease in constitutive NOS activity and gastric mucus level in the gastric mucosa induced by IR were significantly prevented. However, the protective effect mediated by L-citrulline was significantly antagonized by coadministration of L-nitroarginine methyl ester (10 mg/kg, s.c.). These results suggest that part of the mechanism of gastric protection by L-citrulline might be through inhibiting neutrophil infiltration and preserving gastric mucus synthesis and secretion in rats, functions that are closely related to the maintenance of constitutive NOS activity.     

Protective effects of ascorbic acid, Dl-α-tocopherol acetate, and sodium selenate on ethanol-induced gastric mucosal injury of rats

In this study, the effect of ascorbic acid (vitamin C), Dl-α-tocopherol acetate (vitamin E), and sodium selenate (selenium) on ethanol-induced gastric mucosal injury in rats was investigated morphologically and biochemically. The gastric mucosal injury was produced by administration of 1 mL of absolute ethanol to each rat. Animals received vitamin C (250 mg/kg), vitamin E (250 mg/kg), and selenium (0.5 mg/kg) for 3 d 1 h prior to the administration of absolute ethanol. In gastric mucosa of rats given ethanol according to control groups, neuronal nitric oxide expression decreased. This immunoreactivity was much lower in the group given ethanol+vitamin C+vitamin E+selenium than the control group and the ethanol-induced group. Scanning electron microscopic evaluation of the ethanol-induced group, when compared to control groups, revealed degenerative changes in gastric mucosa, whereas a good arrangement in surface topography of gastric mucosa in the group given ethanol + vitamin C+vitamin E + selenium was observed. In the group administered ethanol, a reduction of the stomach glutathione (GSH) and serum total protein levels and increases in serum sialic acid, triglycerides, and stomach lipid peroxidation (LPO) levels were observed. Vitamin C+vitamin E+Se administration to alcohol-treated rats significantly increased the serum total protein, triglyceride levels, and stomach GSH levels and significantly lowered the levels of serum sialic acid and stomach LPO compared to untreated alcohol-supplemented rats. As a result of these findings, we can say that the combination of vitamin C, vitamin E, and selenium has a protective effect on ethanol-induced gastric mucosal injury of rats.     

Gastroprotective and vasodilatory effects of epidermal growth factor: the role of sensory afferent neurons

Epidermal growth factor (EGF) has been shown to exert gastric hyperemic and gastroprotective effects via capsaicin-sensitive afferent neurons, including the release of calcitonin gene-related peptide (CGRP). We examined the protective and vasodilatory effects of EGF on the gastric mucosa and its interaction with sensory nerves, CGRP, and nitric oxide (NO) in anesthetized rats. Intragastric EGF (10 or 30 microg) significantly reduced gastric mucosal lesions induced by intragastric 60% ethanol (50.6% by 10 microg EGF and 70.0% by 30 microg EGF). The protective effect of EGF was significantly inhibited by pretreatment with capsaicin desensitization, human CGRP1 antagonist hCGRP-(8-37), or N(omega)-nitro-L-arginine methyl ester (L-NAME). Intravital microscopy showed that topically applied EGF (10-1,000 microg/ml) dilated the gastric mucosal arterioles dose dependently and that this vasodilatory effect was significantly inhibited by equivalent pretreatments. These findings suggest that EGF plays a protective role against ethanol-induced gastric mucosal injury, possibly by dilating the gastric mucosal arterioles via capsaicin-sensitive afferent neurons involving CGRP and NO mechanisms.