Effect of cysteine on gastric mucosal lesion induced by restraint water-immersion in rats

目的：研究半胱氨酸对大鼠胃溃疡的影响及其作用机制。方法：利用大鼠浸水应激性胃溃疡模型，观察腹注盐酸半胱氨酸对胃溃疡指数、胃粘膜谷胱甘肽（ＧＳＨ）含量、胃酸分泌和胃粘液分泌的影响。结果：半胱氨酸能抑制大鼠胃溃疡的形成；浸水应激可使大鼠胃粘膜ＧＳＨ含量明显降低，半胱氨酸对ＧＳＨ含量的降低无影响；事先给予Ｎ－乙酰马来酰氨（Ｎ－ｅｔｈｙｌｍａｌｅｉｍｉｄｅ，ＮＥＭ）或消炎痛对半胱氨酸的抗溃疡作用无影响；半胱氨酸能抑制浸水应激大鼠胃酸的分泌，但对胃粘液的分泌无影响。结论：半胱氨酸的抗溃疡作用与其抑制胃酸分泌有关，而与胃粘液的分泌、胃粘膜ＧＳＨ和前列腺素的作用无关。     

半胱氨酸对大鼠浸水应激性胃溃疡的影响

目的；研究半胱氨酸对大鼠胃溃疡的影响及其作用机制，方法：利用大鼠浸水应激性胃溃疡模型，观察腹注盐酸半胱氨酸对胃溃疡指数、胃粘膜谷胱甘肽（ＧＳＨ）含量１胃酸分泌和胃粘液分泌的影响。结果：半胱氨酸能抑制大鼠胃溃疡的形成；浸水应激可使大鼠胃粘膜ＧＳＨ含量明显降低，半胱氨酸对ＧＳＨ含量的降低无影响；事先给予Ｎ－乙酰马来酰氨或消炎痛对半胱氨酸的抗溃疡作用无影响；半胱氨酸能抑制浸水应激大鼠胃酸的分泌，但对胃粘     

大黄防治实验性胃粘膜损伤机理分析

本工作通过观察测定胃酸分泌,胃排空运动和胃壁粘液分泌的变化,初步探讨了中药大黄水浸煎剂对乙醇和消炎痛造成胃粘膜损伤的防治机理。结果表明:中药大黄可抑制胃排空速度,促进胃壁粘液分泌,并能预防乙醇和消炎痛造成的胃粘膜损伤,治疗乙醇造成的胃粘膜损伤。提示:中药大黄防治胃粘膜损伤机理与抑制胃酸分泌、抑制胃排空和促进胃壁粘液分泌有关。     

硝普钠对大鼠应激性胃粘膜损伤的保护作用

采用浸水束缚应激法建立大鼠应激性胃溃疡模型，观察一氧化氮供体硝普钠对大鼠胃粘膜损伤的保护作用。结果表明，硝普钠可以明显减轻浸水应激引起的胃粘膜损伤，抑制胃运动亢进，同时增加胃粘膜血流量以及血浆和胃粘膜中NO和SOD含量，降低MDA和ET含量。提示硝普钠对浸水应激性胃粘膜损伤的保护作用可能是通过增加胃粘膜血流量和抑制胃运动亢进共同实现的。     

硝普钠对大鼠应激性胃粘膜损伤的保护作用

采用浸水束缚应激法建立大鼠应激性胃溃疡模型，观察一氧化氮供体硝普钠对大鼠胃粘膜损伤的保护作用。结果表明，硝普钠可以明显减轻浸水应激引起的胃粘膜损伤，抑制胃运动亢进，同时增加胃粘膜血流量以及血浆和胃粘膜中NO和SOD含量，降低MDA和ET含量。提示硝普钠对浸水应激性胃粘膜损伤的保护作用可能是通过增加胃粘膜血流量和抑制胃运动亢进共同实现的。     

缺血预适应在大鼠肢体缺血再灌注后胃粘膜损伤中的作用

目的:观察肢体缺血再灌注(LIR)对胃粘膜的损伤,探讨肢体缺血再灌注对胃粘膜损伤的作用及其部分机制,以及短暂多次肢体缺血在胃粘膜损伤发生中的作用。方法:按Rosenthal方法复制大鼠LIR模型,观察并测定肢体缺血4h再灌注4h后以及应用缺血预适应干预对胃粘膜损伤的影响:取各组胃粘膜制作切片于光学显微镜和电子显微镜下进行观察,测定各组胃粘膜损伤指数、胃粘膜血流量(GMBF)、胃结合粘液量、胃粘液中磷脂、氨基己糖的含量、血浆和胃组织一氧化氮含量以及胃粘膜一氧化氮合酶(NOS)活性。结果:光学显微镜和电子显微镜观察结果显示大鼠LIR后胃粘膜损伤严重,IPC组各类细胞损伤较LIR组轻;LIR后GMBF及胃结合粘液量、胃粘液中磷脂、氨基己糖的含量均低于对照组,虽然IPC组大部分指标与对照组有差异,但与LIR组对比GMBF及胃结合粘液量、胃粘液中磷脂、氨基己糖的含量均较高于LIR组;LIR组血浆与胃粘膜组织NO含量及NOS活性显著高于对照组,而IPC组血浆与胃粘膜组织NO含量和胃粘膜的NOS活性又显著高于LIR组。结论:肢体缺血再灌注可导致胃粘膜损伤;缺血预适应可减轻肢体缺血再灌注后的胃粘膜损伤。     

花生油灌胃对大鼠浸水应激性胃溃疡和胃运动的影响

采用束缚-浸水应激法建立大鼠应激性胃溃疡模型,观察花生油对胃粘膜损伤程度和胃运动的影响.结果表明,花生油可以明显减轻胃粘膜损伤,明显抑制胃运动,但对胃粘膜血流量无影响.提示抑制胃运动可能是花生油保护大鼠浸水应激性胃粘膜损伤的机制之一.     

花生油灌胃对大鼠浸水应激性胃溃疡和胃运动的影响

采用束缚－浸水应激法建立大鼠应激性胃溃疡模型,观察花生油对胃粘膜损伤程度和胃运动的影响。结果表明,花生油可以明显减轻胃粘膜损伤,明显抑制胃运动,但对胃粘膜血流量无影响。提示抑制胃运动可能是花生油保护大鼠浸水应激性胃粘膜膜损伤的机制之一。     

内源性一氧化氮预防大鼠乙醇性胃粘膜损伤的研究

目的：探讨内源性一氧化氮在大鼠乙醇性胃粘膜损伤时保护胃粘膜作用及机制。方法：大鼠７２ 只,随机分为４ 组,正常对照组,单纯乙醇灌胃（Ｅｔｈ） 组,Ｌ－ 精氨酸＋ 乙醇（Ｌ－ ａｒｇ ＋ Ｅｔｈ） 组,Ｌ－ 硝基精氨酸＋ 乙醇（Ｌ－ ＮＮＡ＋Ｅｔｈ） 组,观察其血浆ＮＯ 含量对胃粘膜的大体及组织学损伤程度、胃粘膜血流量（ｇａｓｔｒｉｃ ｍｕｃｏｓａｌ ｂｌｏｏｄ ｆｌｏｗ ,ＧＭＢＦ） 和胃粘液分泌量的影响。结果：Ｅｔｈ 组血浆ＮＯ 含量,ＧＭＢＦ 和粘液分泌量明显少于对照组（ Ｐ 均＜ ０－０５） ,Ｌ－ ａｒｇ ＋ Ｅｔｈ 组血浆ＮＯ 含量,ＧＭＢＦ 和粘液分泌量明显多于Ｅｔｈ 组（ Ｐ 均＜ ０ ．０５） ,而乙醇对胃粘膜损伤明显减轻（ Ｐ＜ ０－０５） ,Ｌ－ ＮＮＡ ＋ Ｅｔｈ组血浆ＮＯ 含量ＧＭＢＦ 和粘液分泌量明显少于前３ 组（ Ｐ 均＜ ０－０５） ,而胃粘膜损伤程度明显较重（ Ｐ＜ ０－０５） 。结论：内源性ＮＯ 保护胃粘膜对抗乙醇引起的损伤,是通过增加胃粘膜血流量和促进粘液分泌而实现的。     

一氧化氮与利血平致大鼠胃粘膜损伤的关系

目的: 探讨一氧化氮(NO)与利血平致大鼠胃粘膜损伤机制的关系。方法: 从大鼠腹腔内注入利血平复制成胃粘膜损伤模型,并随机分为实验组和对照组。用镉还原加格氏显色法和改良硫代巴比妥酸法分别测定两组大鼠血浆及胃粘膜中NO和丙二醛(MDA)含量,用还原型辅酶Ⅱ组织化学方法结合图像分析对两组大鼠胃壁内一氧化氮合酶(NOS)进行定位、定量研究。结果: 实验组大鼠血浆、胃粘膜中NO含量显著低于对照组(P＜0.01),而其MDA含量则显著高于对照组(P＜0.05,P＜0.01);实验组大鼠胃壁内NOS阳性神经细胞、阳性神经纤维密度及其着色深度均显著低于对照组(P＜0.05,P＜0.01)。结论: 利血平致大鼠胃粘膜损伤的发生可能与大鼠胃壁内NOS阳性神经成分减少,体内NO不足使其对胃粘膜的保护作用减弱有一定关系。     

Effect of <Emphasis Type="Italic">Cannabis sativa</Emphasis> extract on gastric acid secretion,oxidative stress and gastric mucosal integrity in rats

Studies were conducted in pylorus-ligated rats to investigate the effect of Cannabis sativa extract on gastric acid secretion, experimental gastric ulcer and on oxidative stress and inflammatory markers in the gastric mucosa. C. sativa (5, 10 and 20 mg/kg, expressed as Δ⁹-tetrahydrocannabinol) was administered subcutaneously daily for 4 weeks prior to pylorus ligation and different treatments. Under basal conditions, pretreatment with cannabis extract at doses of 5 and 10 mg/kg increased gastric acid secretion and induced minimally visible gastric mucosal lesions in the 4 h pylorus-ligated rat. Malondialdehyde and nitric acid concentration increased, while reduced glutathione decreased by cannabis at doses of 5 and 10 mg/kg in gastric mucosa. TNF-α increased by cannabis extract at doses of 5 and 10 mg/kg but decreased following the high dose of 20 mg/kg. On the other hand, the gastric acid secretory responses stimulated by pentagastrin or carbachol (but not histamine) were inhibited in rats pretreated with cannabis extract. Under these conditions, cannabis decreased pepsin content after pentagastrin and carbachol but not histamine stimulation. Cannabis also decreased lipid peroxidation and nitric oxide content, and increased both reduced glutathione and catalase activity in mucosa. Moreover, cannabis decreased mucosal inflammation (level of TNF-α) and the development of gastric mucosal lesions. Cannabis administered for 1 month prior to pylorus-ligation and either acidified aspirin or ethanol (96 %) decreased the development of gastric mucosal damage in a dose-dependent manner, along with reduction in gastric acid output, gastric mucosal oxidative stress and inflammation (TNF-α). Sections of gastric mucosa stained with periodic acid Schiff showed increased mucus secretion by cannabis in basal conditions and after treatment with aspirin or ethanol. Results indicate that: (1) the effect of cannabis differs in basal conditions and after exposure of the gastric mucosa to high acid concentrations or other chemical noxious agents; (2) cannabis administered systemically exerts gastric mucosal protective effects against mucosal damage evoked by stimulation of gastric acid secretion, acidified aspirin or ethanol. These effects of cannabis are likely to involve inhibition of gastric acid and pepsin secretion, increased mucus, decreased oxidative stress and inflammation in gastric mucosa.     

A study of the antiulcer mechanisms of propanolol in rats

Although propranolol has been shown to protect against enthanol and stress ulceration, the antiulcer mechanisms are still unclear. The present study examined the antiulcer mechanisms of propranolol in three different types of ulceration induced respectively by ethanol (60%), indomethacin (30 mg/kg) and stress (cold-restraint). Propranolol pretreatment in the highest dose (10 mg/kg) given either intraperitoneally (i.p.) or orally (p.o.) prevented gastric mucosal damage in these three ulcer models. The three doses of the drug (2.5, 5 or 10 mg/kg) dose-dependently decreased systemic blood pressure which was accompanied by a reduction of gastric mucosal blood flow. These findings suggest that the protection was unrelated to an improvement of local circulation in the stomach. However, propranolol preserved the mucus levels in the three types of ulcer models. The -adrenoceptor blocker also increased the basal gastric mucosal potential difference. These findings indicate that propranolol strengthens the mucosal barrier by the preservation of mucosal mucus and enhancement of the mucosal integrity in the stomach.accepted by R. O. Day     

缺氧新生鼠胃壁内一氧化氮合成酶定量和定位研究

为探讨缺氧新生鼠胃壁局部一氧化氮（ＮＯ）的改变,本文直接测定其胃壁一氧化氮合成酶（ＮＯＳ）活性,并采用ＮＡＤＰＨ二氢硫辛酰胺脱氢酶组织化学方法（ＮＤ法）观察胃壁各层ＮＯＳ分布的变化,结果发现：急性缺氧组与正常组相比,差异无显著性（Ｐ＞０．０５）。但在缺氧缺血性脑病（ＨＩＥ）组,胃壁ＮＯＳ活性明显增高（Ｐ＜０．０１）,ＮＤ法定位显示ＮＯＳ阳性纤维及胞体明显增多表现在肌层,而粘膜及粘膜下层变化不明显。说明窒息时胃动力降低及胃粘膜病变与ＮＯ在胃壁内的改变有关。     

Role of nitric oxide in the gastro-protective effect of lithium.

Background and aim: Lithium is widely used for the management of neuropsychiatric symptoms in bipolar disorders. A few studies have shown that lithium has a protective effect against gastric damage with an unknown mechanism. Some of the actions of lithium are mediated through nitric oxide (NO), which has an important role in the regulation of gastric wall blood flow as well as gastric mucosal integrity. The aim of this study was to test the hypothesis if the gastro-protective effect of lithium is mediated through NO. Methods: Male Wistar rats were pre-treated with either a non-selective NO synthase inhibitor (N(G)-nitro-l-arginine, 10mg/kg), a selective inducible NO synthase inhibitor (aminoguanidine, 100mg/kg) or saline. Lithium carbonate (10, 20, 50 and 100mg/kg) was then administered intraperitoneally 1h before the induction of gastric mucosal damage. Gastric damage was induced by either water immersion stress or ethanol gavage in rats. Results: Lithium had a significant protective effect in both stress and ethanol-induced gastric damage, but it needed in ethanol-induced gastric damage a higher dose than in the stress induced lesion. Lithium carbonate doses 20 and 50mg/kg produced plasma concentrations that were in the range of human therapeutic Li levels (0.6-1.0muM). Pre-treatment of animals with N(G)-nitro-l-arginine (20 and 40mg/kg) reduced the protective effect of lithium against ethanol-induced gastric damage, but not in stress-induced damage. Aminoguanidine administration showed no effect on the damage reduction either in control or lithium treated rats. Conclusions: The results indicate that NO might play a role in the gastro-protective effect of lithium against ethanol-induced gastric damage in rats.     

Co-regulation of mucosal nitric oxide and prostaglandin in gastric adaptive cytoprotection

OBJECTIVE: The correlation between mucosal generation of nitric oxide (NO) and prostaglandin E2 (PGE2) in gastric adaptive cytoprotection was investigated. MATERIALS AND TREATMENT: Male Sprague-Dawley rats were pretreated with either N(w)-nitro-L-arginine methyl ester (L-NAME, 12.5 mg/kg i.v.) or indomethacin (5 mg/kg s.c.). Following that, mild irritant 20% ethanol was administered, 15 min prior to 100% ethanol challenge. METHODS: Macroscopic gastric mucosal damage, NO synthase activity, mucosal PGE2 and leukotriene C4 (LTC4) levels were measured. RESULTS: Administration of L-NAME and indomethacin significantly reduced the protective action of 20% ethanol against 100% ethanol-induced gastric mucosal damage. Besides, mucosal activity of constitutive NO (cNO) synthase, but not of the inducible isozyme (iNO synthase), was elevated following 20% ethanol treatment. This was accompanied by a reduction in mucosal leukotriene C4 level. Indomethacin significantly inhibited mucosal PGE2 biosynthesis but increased cNO synthase activity. Nevertheless, L-NAME reduced both cNO and iNO formation and prevented the increase in cNO formation caused by 20% ethanol, while enhancing mucosal PGE2 production. Combined L-NAME and indomethacin treatment markedly potentiated ethanol-induced mucosal damage, and completely prevented the increase in cNO or PGE2 biosynthesis when either compound was given alone. CONCLUSIONS: These findings suggest a co-regulatory relationship between mucosal NO and PG in the gastric defense system, which will be released after activation by the mild irritants to induce cytoprotection.     

Role of prostaglandins and nitric oxide in gastric damage induced by metamizol in rats

OBJECTIVE AND DESIGN: In addition to the depletion of prostaglandins (PGs), oxygen free radicals generation and nitrogen species haven been implicated in non-steroidal anti-inflammatory drugs (NSAIDs)-induced gastric injury. The aim of the present study was to examine changes in PGE2 generation and its relationship with proinflammatory parameters and nitric oxide (NO) production in the comparative pathogenesis of gastric injury induced by metamizol vs. diclofenac, NSAIDs that present different gastric tolerability and cyclooxygenase (COX) inhibition profiles. MATERIAL: Studies were performed in Wistar-Han rats. TREATMENTS: Metamizol (120, 500 and 1,000 mg/kg body weight) and diclofenac (50 mg/kg body weight) were given by oral administration. METHODS: Determinations were made of macroscopic and histological evaluation of gastric mucosal injury, gastric prostaglandin synthesis (PGE2 levels), myeloperoxidase activity (MPO), tumor necrosis factor-alpha levels (TNF-a), cyclic guanosine monophosphate (cGMP), nitric oxide synthase activity (NOS) and NOS mRNA expression. RESULTS: Metamizol, only at the highest doses assayed, provoked weak lesions in the gastric mucosa. To the contrary, diclofenac treatment presented the highest grade of lesion. All treatments decreased PGE2 gastric generation. Treatment of the animals with metamizol neither modified the MPO activity nor TNF-alpha levels. In contrast, statistically significant increases in both parameters were observed after diclofenac administration. cGMP levels were not influenced with diclofenac treatment, nevertheless metamizol reduced the nucleotide levels, which was accompanied by an inhibition of constitutive NOS (cNOS) activity without modifying the mRNA expression of the enzyme. CONCLUSIONS: In addition to inhibition of PG synthesis, damage induced by metamizol was associated with an inhibition of the NO/cGMP pathway and cNOS activity. In contrast, diclofenac-induced gastric damage was associated with an increase of the inflammatory response.