Management of Citrus sinensis peels for protection and treatment against gastric ulcer induced by ethanol in rats

Abstract

Introduction: Stomach ulcer is one of the most prevalent disorders worldwide. The study was aimed to isolate and characterize the major polymethoxylated flavonoids in Citrus sinensis peels petroleum ether extract and investigate its protective and curative effect on gastric ulcer.

Material and methods: Some spectral analyses were used for identification of the isolated compounds from the petroleum ether extract of Citrus sinensis peels. One oral dose (0.5?ml/100?g b.wt.) of absolute ethanol was orally given to rats after starvation for 24?h to induce gastric ulcer. To explore the protective and curative role of the plant extract, it was orally (250?mg/kg b.wt.) given for 1 week either before or post-ulcer induction. A reference drug, ranitidine (100?mg/kg b.wt.), was also evaluated. Stomach acidity, gastric volume, lesion counts, glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA), succinate dehydrogenase (SDH), lactate dehydrogenase (LDH), acid phosphatase (AP), interlukin-10 (IL-10) and prostaglandin E2 (PGE2) were estimated. Stomach histopathological features were monitored.

Results: Nine polymethoxy flavonoids were identified from the extract. Treatment with C. sinensis peels extract recorded amelioration in all parameters.

Conclusion: Citrus sinensis petroleum ether peels extract had protective and curative effects against gastric ulcer. Therefore, the extract recorded anti-secretory, anti-ulcerative, anti-inflammatory, and antioxidant effects. Its healing action exceeded its protective role due to its richness in polymethoxylated flavonoids     

Protective and therapeutic effects of Argyreia speciosa against ethanol-induced gastric ulcer in rats

The protective and therapeutic effects of Argyreia speciosa Sweet (Convolvulaceae) against ethanol-induced gastric ulcer in rats were evaluated. Ethanolic and water extracts of the aerial plant parts (200 mg/kg body weight) were orally administered daily for seven days prior to or after ulceration with one oral dose of 1 mL absolute ethanol on 24-h empty stomachs. Rats were divided into eleven groups. Group 1 served as control. To groups 2 and 3 each extract was administered. Groups 4 to 6 received each extract or ranitidine (100 mg/kg body weight) prior to ulcer induction. Groups 7 to 9 received each extract or ranitidine post ulcer induction. Groups 10 and 11 were gastric ulcerative rats after one hour and one week of ethanol induction. The evaluation was done through measuring ulcer indices: stomach acidity and volume, lesion counts, mucus, and prostaglandin E2 contents. Oxidative stress marker, i. e. malondialdehyde, glutathione, and superoxide dismutase, were estimated. Certain marker enzymes for different cell organelles, i. e. succinate and lactate dehydrogenases, glucose-6-phosphatase, acid phosphatase, and 5'-nucleotidase, were evaluated. The work was extended to determine the collagen content and the histopathological assessment of the stomach. Gastric ulcer exhibited a significant elevation of the ulcer index, antioxidant levels, collagen content, and the marker enzymes. The water extract attenuated these increments and was more potent as a protective agent, while the ethanol extract exhibited stronger therapeutic potency. In conclusion, A. speciosa acted as antiulcer agent. More detailed studies are required to identify the compounds responsible for the pharmacological effect.     

Somatostatin-induced gastric protection against ethanol: involvement of nitric oxide and effects on gastric mucosal blood flow

BACKGROUND--AIMS:The mechanisms of somatostatin-mediated gastroprotection are not fully understood. Aims of this study were to determine in the rat the role of nitric oxide (NO) in somatostatin-induced effects on gastric mucosal protection and blood flow (GMBF) in the absence and in the presence of intraluminal ethanol. METHODS: Ethanol (70% v/v)-induced gastric mucosal injury after orogastric dosing was quantitated at 30 min and GMBF determined in an ex vivo gastric chamber preparation. RESULTS: Somatostatin (4 microg/kg; i.p.) protection against ethanol-induced ulceration was prevented by the NO inhibitor L-NNA and restored by L-arginine, but not D-arginine. Somatostatin (1-8 microg/kg; i.p.) did not effect basal GMBF. The gastroprotective dose of somatostatin (4 microg/kg; i.p.) prevented the decrease in GMBF caused by ethanol. L-NNA reversed this vascular effect of somatostatin. CONCLUSION: Somatostatin-induced gastroprotection and restoration of GMBF during ethanol exposure involve mechanisms which are dependent on NO generation.     

Sucralfate protection of gastric mucosa against alcohol-induced injury: a phosphoinositide mediated process

The mechanism of protection by sucralfate against gastric mucosal injury induced by ethanol was investigated. The experiments in vivo were conducted with groups of rats with and without indomethacin pretreatment, and the animals received sucralfate followed by ethanol. In the in vitro experiments, gastric mucosa was cultured in the presence of sucralfate, ethanol, or both. The in vivo experiments revealed that ethanol caused extensive gastric hemorrhagic lesions which were significantly reduced following sucralfate pretreatment and that this effect of sucralfate was not prevented by indomethacin. The data with gastric mucosal culture demonstrated that ethanol caused a 24% decrease in mucin synthesis, while mucin synthesis in the presence of sucralfate increased by 32%. This increase was accompanied by the enhanced metabolism of mucosal phosphoinositides, as reflected by a 22% decrease in PI, 1,2-fold increase in IP1 and 3.4-fold increase in IP3. In contrast, ethanol, caused 1.5-fold increase in IP1 and PIP2, and 35% decrease in PIP, 47% decrease in IP2 and 38% decrease in IP3. However, when the mucosal culture was carried out in the presence of both sucralfate and ethanol, the detrimental changes evoked by ethanol in mucin synthesis were prevented. The results suggest that the mucosal protective action of sucralfate involves the metabolism of phosphoinositide-derived messenger molecules.     

Novel role of famotidine in downregulation of matrix metalloproteinase-9 during protection of ethanol-induced acute gastric ulcer

Gastric ulcer is a multifaceted process including acid secretion, reactive oxygen species generation, prostaglandin inhibition, and extracellular matrix (ECM) degradation. Matrix metalloproteinases (MMPs) have the ability to cleave and remodel the ECM. We investigated the activity and expression of MMP-9 and -2 in ethanol-induced acute gastric ulceration in rats. We found that severity of gastric ulcer was strongly correlated with increasing doses of ethanol and increased secretion of proMMP-9. ProMMP-9 was upregulated approximately 25-fold at maximum ulcer index. Increased secretion of proMMP-9 was associated with increased expression of tumor necrosis factor-alpha and interleukin-6. We examined the effect of H(2)-receptor antagonists and antioxidants on proMMP-9 secretion and synthesis during prevention of ethanol-induced gastric ulcer. Our data reveal that famotidine dose dependently blocked increased secretion and synthesis of proMMP-9 during gastroprotection and arrested infiltration of inflammatory cells as well as oxidative stress in rat gastric tissues. Similar to H(2)-receptor antagonists, N-acetylcysteine and dimethyl sulfoxide, well-known antioxidants, inhibited proMMP-9 upregulation to the control level. In conclusion, ethanol-induced gastric ulceration is associated with increased expression of proMMP-9 that can be attenuated by H(2)-receptor antagonists and antioxidants. These findings furnish a novel MMP-9-mediated pathway and its inhibition via proinflammatory cytokines by famotidine in ethanol-induced gastric ulceration.     

Mechanisms involved in gastric protection of melatonin against oxidant stress by ischemia-reperfusion in rats

The generation of oxygen-derived free radicals has been suggested to be significantly responsible for ischemia-reperfusion injury in gastrointestinal tissues. Biochemical mechanisms include the xanthine-oxidase-derived oxidants mainly the superoxide anion. Both in vitro and in vivo studies have demonstrated that the pineal hormone melatonin possesses free radical scavenging and antioxidant properties. The indolamine has been effective in reducing the induced-oxidative damage in several tissues and biological systems. The aim of this study was to elucidate additional antioxidant mechanisms responsible for the gastroprotection afforded by the indolamine in ischemia-reperfusion gastric injury. Therefore, changes of related enzymes such as xanthine-oxidase, superoxide dismutase, glutathione reductase and total glutathione were investigated. Our results showed that treatment with 5, 10 or 20 mg kg(-1) of melatonin, administered i.p., clearly diminished the percentage of damage to 49.56 +/- 17.20, 37.54 +/- 11.40 and 26.70 +/- 8.12 respectively. Histologically there was a reduction of exfoliation of superficial cells and blood cell infiltration. These protective effects were related to a significant reduction of xanthine-oxidase activity (2.23 +/- 0.38 U/mg prot x 10(-4) with the highest tested dose of melatonin) and significant increases in superoxide dismutase reaching a value of 6.20 +/- 0.56 U/mg prot with 25 mg/Kg of melatonin and glutation reductase activities (417.44 +/- 29.72 and 649.43 +/- 81.11 nmol/min/mg prot with 10 and 20 mg/Kg of melatonin). We conclude that the free radical scavenger properties of melatonin mainly of the superoxide anion, probably derived via the xanthine-oxidase pathway, and the increase of antioxidative enzymes significantly contributes to mediating the protection by the hormone against ischemia-reperfusion gastric injury.     

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。     

Over-expression of 70-kDa heat shock protein confers protection against monochloramine-induced gastric mucosal cell injury

The major heat shock protein, HSP70, is known to be involved in cytoprotection against environmental stresses mediated by their function as a "molecular chaperone". Monochloramine (NH(2)Cl) is a potent cytotoxic oxidant generated by neutrophil-derived hypochlorous acid and Helicobacter pylori urease-induced ammonia. In this study, to evaluate the cytoprotective effect of HSP70 against NH(2)Cl-induced gastric mucosal cell injury, rat gastric mucosal cells (RGM-1) were stably transfected with pBK-CMV containing the human HSP70 gene (7018-RGM-1) or pBK-CMV alone (pBK-CMV-12) as control cells. These cells were treated with various concentrations of NH(2)Cl. Cell Viability was determined by MTT assay and the direct plasma membrane damage was analyzed by lactate dehydrogenase (LDH) release assay. Apoptosis was determined by DNA fragmentation analysis. NH(2)Cl caused injury to pBK-CMV-12 cells in a concentration-dependent manner. NH(2)Cl-induced gastric cell injury was significantly diminished in HSP70 over-expressing cell line (7018-RGM-1) both necrosis and apoptosis compared to the control cell line (pBK-CMV-12) transfected with CMV vector alone. These result suggest that overexpression of HSP70 plays an important role in protecting gastric cells against NH(2)Cl-induced injury.