Nicotine induced gastric injury. A quantitative macroscopic and microscopic analysis of the protective effects of sucralfate and feeding

Ethanolic extract of roots from Arctium lappa L. accelerates the healing of acetic acid-induced gastric ulcer in rats: Involvement of the antioxidant system

We evaluate the curative efficacy of the ethanolic extract (EET) of roots from Arctium lappa (bardana) in healing of chronic gastric ulcers induced by 80% acetic acid in rats and additionally studies the possible mechanisms underlying this action. Oral administration of EET (1, 3, 10 and 30mg/kg) reduced the gastric lesion area in 29.2%, 41.4%, 59.3% and 38.5%, respectively, and at 10mg/kg promoted significant regeneration of the gastric mucosa, which was confirmed by proliferating cell nuclear antigen immunohistochemistry. EET (10mg/kg) treatment did not increase the gastric mucus content but restored the superoxide dismutase activity, prevented the reduction of glutathione levels, reduced lipid hydroperoxides levels, inhibited the myeloperoxidase activity and reduced the microvascular permeability. In addition, EET reduced the free radical generation and increased scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals in vitro. Furthermore, intraduodenal EET (10 and 30mg/kg) decreased volume and acidity of gastric secretion. Total phenolic compounds were high in EET (Folin-Ciocalteau assay) and the analysis by liquid chromatography-mass spectrometry revealed that the main compounds present in EET were a serie of hydroxycinnamoylquinic acid isomers. In conclusion, these data reveal that EET promotes regeneration of damaged gastric mucosa, probably through its antisecretory and antioxidative mechanisms.

Coenzyme Q10: a novel gastroprotective effect via modulation of vascular permeability, prostaglandin E₂, nitric oxide and redox status in indomethacin-induced gastric ulcer model

Coenzyme Q10 is an essential cofactor in the mitochondrial electron transport pathway, and is endowed for its potent antioxidant capacity; characters that endorse its implication in several clinical practices and as a food supplement. Nevertheless, its potential gastro-protective effect, in acute models, has never been assessed, which is the objective of this study. Since indomethacin mediated gastropathy is multifaceted, including mitochondrial dysfunction and generation of reactive oxygen species, thus, the indomethacin-induced gastric injury serves as a convenient animal model for this work. Rats treated with indomethacin revealed mucosal hemorrhagic lesions, increased microvascular permeability and inhibited prostaglandin E₂ and mucus content. Redox imbalance was reflected by decreased mucosal glutathione (GSH), nitric oxide and glutathione peroxidase contents/activity, along with elevated lipid peroxides. Pretreatment with CoQ10 caused discernible decrease in indomethacin-induced gastric lesions, vascular permeability and lipid peroxide content. In addition, prostaglandin E₂ and GSH levels were restored, while those of nitric oxide and glutathione peroxidase were elevated significantly above normal; however, mucus formation was not altered significantly. The positive effects were comparable to those of sucralfate, the standard drug used herein, except for the mucus and prostaglandin E₂ levels that were increased above normal by sucralfate. CoQ10-mediated gastroprotective effect involves preservation of microvascular permeability, elevation of prostaglandin E₂, improvement of redox status, as well as boosting of nitric oxide. Nevertheless, maintaining gastric mucus content is ruled out.

Nicotine withdrawal alleviates acetic acid-induced gastric injury in rats

Epidemiological and experimental studies have demonstrated that cigarette smoking intensifies gastric ulceration. Although nicotine can act as an anxiolytic and antidepressant, its withdrawal may also lead to increased anxiety and depression. In order to associate the toxic actions of nicotine on gastric mucosa with alterations of anxiety level and to evaluate the impact of nicotine withdrawal on the anxiety level and the severity of ulcer, an acetic acid-induced ulcer model was used. Male Sprague-Dawley rats were given either tap water or nicotine bitartarate (50μg/ml in drinking water) for 15 days, while another group of rats had 5 days of withdrawal following 10 days of nicotine treatment. Ulcer was induced by acetic acid on the 15th day of the treatments, and the rats were followed for 3 days until they were decapitated and the gastric tissues were obtained. Using the hole-board test, basal anxiety levels measured on the first day of the treatments were compared with the measurements made at the early and late phases of ulcer induction. Chronic administration of nicotine did not have a potentiating effect on acetic acid-induced gastric ulcer, since the gastric injury, as assessed by both macroscopic and microscopic evaluation and increased gastric myeloperoxidase activity indicating neutrophil recruitment, was not exaggerated or attenuated by nicotine intake. On the other hand, nicotine withdrawal attenuated gastric mucosal injury, despite an increased level of anxiety. Smoking cessation, which triggers the onset of depressive symptoms with nicotine withdrawal, still has a worthwhile positive effect on the gastric mucosa.

Nicotine suppresses gastric wound repair via the inhibition of polyamine and K(+) channel expression

Nicotine is one of the most representative components in cigarette smoke leading to gastric ulceration. Both ornithine decarboxylase and potassium ion (K(+)) channels are essential for cell growth and wound repair. The aim of the present study is to elucidate the causative relationship of these two factors during wound healing and the influence of nicotine on this healing process in rat gastric mucosal epithelial cells (RGM-1). Nicotine markedly inhibited cell migration and proliferation in RGM-1 cells. The latter effect was significantly antagonized by a nicotinic receptor blocker, mecamylamine. Nicotine also suppressed ornithine decarboxylase activity significantly. Our data showed that inhibition of cell proliferation and ornithine decarboxylase activity by nicotine was accompanied with a reduction in K(+) channel protein expression, all of which were significantly alleviated by spermidine pretreatment. These results suggested that there was a cause/effect link between ornithine decarboxylase and K(+) channel on wound repair. Nicotine in cigarette smoke inhibited this healing process and delayed wound repair in gastric epithelial cells.

Pathogenesis of nicotine treatment and its withdrawal on stress-induced gastric ulceration in rats

Previous studies showed that cigarette smoking was closely associated with gastric ulceration. People usually smoke under stress conditions, and together, these could induce more gastric damage. In the present study, we aimed to study the effects of nicotine administration and its withdrawal on stress-induced gastric ulceration in rats. Male Sprague-Dawley rats were given nicotine (25 or 50 microg/ml) for 10 days and then withdrawn for 2, 4 or 6 days. They were subjected to cold-restraint stress for 2 h after nicotine treatment or after nicotine withdrawal, and then killed. The results indicated that both nicotine treatment and its withdrawal potentiated stress-induced gastric damage. The mucosal glutathione (GSH) and mucus levels were reduced by stress and decreased further by nicotine. The prostaglandin E(2) concentration remained unchanged. To conclude, the adverse effect of nicotine on stress ulceration was prostaglandin E(2)-independent but mediated by the depression of glutathione and mucus levels in the gastric mucosa.

Can misoprostol and omeprazole reduce nicotine and ethanol induced gastric mucosal injury? A quantitative macroscopic and microscopic analysis in rats

We compared the effects of misoprostol, omeprazole and methylcellulose (control) on gastric mucosal injury induced by nicotine and/or ethanol. The results demonstrate that misoprostol and omeprazole each significantly reduce macroscopic injury and deep injury at a microscopic level (P < 0.05) induced by nicotine alone, ethanol alone or a combination of ethanol and nicotine. Misoprostol and omeprazole each reduced the leakage of fluorescein isothiocyanate-albumin into the interstitium in the gastric mucosa. Misoprostol and omeprazole are each effective in preventing injury induced by nicotine and ethanol and vascular factors are involved.

Aggravation of gastric mucosal lesions in rat stomach by tobacco cigarette smoke

In the model of gastric mucosal injury induced by 2 mol/liter hypertonic saline in rats, we tested the hypothesis that tobacco cigarette smoke aggravates gastric mucosal lesions by inhibition of injury-induced gastric mucosal hyperemia. Experimental rats were treated with tobacco cigarette smoke or nicotine-free smoke from nontobacco cigarettes, and controls breathed room air. Gastric mucosal blood flow was measured by hydrogen gas clearance before and during the intragastric administration of hypertonic saline. Tobacco cigarette smoke 3 and 18 ml/min, but not nicotine-free smoke, significantly attenuated the hyperemia and aggravated the hypertonic saline-induced lesion in a dose-dependent manner. We then tested the hypothesis that 18 ml/min of tobacco cigarette smoke, and the dose of intravenous nicotine previously shown to block injury-induced hyperemia and aggravate 2 mol/liter saline-induced gastric damage, will also adversely affect gastric lesions induced by acidified aspirin or acidified ethanol. The results confirm that tobacco cigarette smoke and intravenous nicotine indeed aggravate gastric mucosal damage in these two models. Taken together, the data suggest that the inhibition of injury-induced hyperemia by nicotine and tobacco cigarette smoke is an important predictor of their ability to increase the susceptibility of the gastric mucosa to noxious damage. Although limited in their experimental nature, these data provide one plausible explanation for the adverse effect of tobacco cigarette smoke on peptic ulcer disease.

Chronic parenterally administered nicotine and stress- or ethanol-induced gastric mucosal damage in rats

Mini-osmotic pumps containing solutions of either 0.9% NaCl (infused at the rate of 0.5 microliter/h) or nicotine (infused in doses of 0.224, 1.03 or 1.88 mg/kg per day) were implanted s.c. into rats 12 days before experimentation. The alkaloid increased solid food consumption, but fluid intake and average weight gain were similar among the animals given saline or nicotine. Chronic nicotine treatment dose dependently intensified cold (4 degrees C)-restraint stress-induced ulceration and increased mast cell degranulation. Oral administration of 40% ethanol to nicotine-treated animals also produced greater mucosal damage; mast cell degranulation by ethanol was significantly worsened after alkaloid treatment. These findings show that the stress ulcer-intensifying action of the alkaloid is mainly through a systemic mechanism. In the case of ethanol-evoked mucosal damage, in addition to a topical effect, stimulation of the stomach wall ganglia is likely to participate in the exaggerated post-vagal ulcerogenic responses as seen in stress.

Effects of smoking and nicotine on the gastric mucosa: a review of clinical and experimental evidence

Epidemiological and experimental evidence have shown that nicotine has harmful effects on the gastric mucosa. The mechanisms by which cigarette smoking or nicotine adversely affect the gastric mucosa have not been fully elucidated. In this report, clinical and experimental data are reviewed. The effects of nicotine from smoking on gastric aggressive or defensive factors are discussed. Nicotine potentiates gastric aggressive factors and attenuates defensive factors; it also increases acid and pepsin secretions, gastric motility, duodenogastric reflux of bile salts, the risk of Helicobacter pylori infection, levels of free radicals, and platelet-activating factor, endothelin generation, and vasopressin secretion. Additionally, nicotine impairs the therapeutic effect of H2-receptor antagonists and decreases prostaglandin synthesis, gastric mucosal blood flow, mucus secretion, and epidermal growth factor secretion. Although many of the studies provide conflicting results, the bulk of the evidence supports the hypothesis that nicotine is harmful to the gastric mucosa.

Chronic nicotine intake causes vascular dysregulation in the rat gastric mucosa

Chronic cigarette smoking has adverse effects on peptic ulcer disease because the healing of ulcers is delayed and the incidence of relapses is enhanced. Short term intake of nicotine induces vascular damage in the rat gastric mucosa, but the pathophysiological mechanisms of nicotine's action in the stomach are largely unknown. In this study rats were treated with nicotine, added to their drinking water, for 50 days. They were then anaesthetised and their stomachs perfused with acidified acetylsalicylic acid (ASA). Chronic nicotine treatment failed to change the effects of acidified ASA to induce gastric mucosal acid back diffusion, haemorrhagic damage and bleeding. Basal blood flow in the gastric mucosa was also unchanged by chronic nicotine intake, whereas the mucosal hyperaemia evoked by ASA induced acid back diffusion was averted. The concentrations of sulfidoleukotrienes were significantly augmented in the gastric wall of nicotine treated rats. These data show that chronic nicotine intake causes dysregulation of the gastric microcirculation, an effect that is associated with biochemical changes in the stomach. This study thus substantiates the adverse effects of smoking on gastric mucosal pathophysiology. These data suggest that inappropriate regulation of gastric mucosal blood flow inhibits recovery from gastric mucosal injury in smokers.

Acute effects of smoking during modified sham feeding in duodenal ulcer patients. An analysis of nicotine, acid secretion, gastrin, catecholamines, epidermal growth factor, prostaglandin E2, and bile acids

Smoking is associated with an increased incidence of duodenal ulcer with a high relapse rate, and smokers tend to be slow healers. The etiology responsible for this remains unknown, and there is general disagreement as to whether smoking affects gastric secretion. The aim of the present study was to investigate both aggressive and protective factors in response to vagal stimulation induced by modified sham feeding (MSF) in duodenal ulcer patients when smoking versus not smoking. On smoking days, nicotine concentrations in plasma averaged about 15 ng/ml and were extremely high in saliva and gastric juice (> 1300 and > 800 ng/ml, respectively). MSF induced a significant decrease in intragastric pH during non-smoking (p = 0.01) but not during smoking. Acid output 1 h after MSF was lower on smoking than on non-smoking days (p = 0.02), as was volume secretion (p = 0.02). Plasma gastrin concentrations were significantly increased during MSF on non-smoking days (p = 0.04) but not on smoking days, the concentrations during the whole day being lower on smoking days (p = 0.002). Plasma catecholamine levels were unaffected by MSF, whether smoking or not. However, plasma concentrations of noradrenaline decreased during the smoking of a single cigarette (p = 0.03), whereas those of adrenaline were increased on smoking days (p = 0.02). Epidermal growth factor concentrations were decreased in gastric juice after MSF during non-smoking (p = 0.01) but not during smoking. Although prostaglandin E2 (PGE2) concentrations in gastric juice were unaffected by MSF, PGE2 output increased after MSF whether smoking or not, the increment being non-significantly less during smoking (p = 0.09).(ABSTRACT TRUNCATED AT 250 WORDS)