Ethanol-induced Mucosal Damage Research Articles

Evidence for the gastric cytoprotective effect of centrally injected agmatine.

Agmatine (decarboxylated arginine) exerts cytoprotective action in several tissues, such as in the brain, heart or kidneys, but there is still controversy over the effects of agmatine on the gastric mucosa. The aim of the present study was to reveal the potential gastroprotective action of agmatine by using an acid-independent ulcer model to clarify which receptors and peripheral factors are involved in it. Gastric mucosal damage was induced by acidified ethanol. Mucosal levels of calcitonin gene-related peptide (CGRP) and somatostatin were determined by radioimmunoassay. For analysis of gastric motor activity the rubber balloon method was used. It was found that agmatine given intracerebroventricularly (i.c.v., 0.044-220 nmol/rat) significantly inhibited the development of ethanol-induced mucosal damage, while in the case of intraperitoneal injection (0.001-50mg/kg i.p.) it had only a minor effect. The central gastroprotective action of agmatine was completely antagonized by mixed alpha2-adrenoceptor and imidazoline I1 receptor antagonists (idazoxan, efaroxan), but only partially by yohimbine (selective alpha2-adrenoceptor antagonist) and AGN 192403 (selective I1 receptor ligand, putative antagonist). It was also inhibited by the non-selective opioid-receptor antagonist naloxone and the selective δ-opioid receptor antagonist naltrindole, but not by β-funaltrexamine and nor-Binaltorphimine (selective μ- and κ-opioid receptor antagonists, respectively). Furthermore, the effect of agmatine was antagonized by bilateral cervical vagotomy and by pretreatment with indomethacin and NG-nitro-l-arginine. Agmatine also reversed the ethanol-induced reduction of gastric mucosal CGRP and somatostatin content, but did not have any significant effect on gastric motor activity. These results indicate that agmatine given centrally induces gastric cytoprotection, which is mediated by central imidazoline I1 receptors, alpha2-adrenoceptors and δ-opioid receptors. Activation of these receptors induces the release of different mucosal protective factors, such as NO, prostaglandins, CGRP and somatostatin by a vagal-dependent mechanism. Alterations of gastric motility are not likely to contribute to the observed protective effect.

Protection by almagate of ethanol-induced gastric mucosal damage in rats.

The study was designed to analyse the protective effects of almagate on a model of gastric injury, ethanol-induced mucosal damage, in which acid plays little, if any, role. Pretreatment with almagate dose-dependently reduced the level of gastric damage induced by oral administration of 1 mL 100% ethanol. Administration of 12 mumol kg-1 alamagate 30 min before ethanol significantly reduced the area of mucosal damage by 65 +/- 10%, and the maximum level of inhibition (74 +/- 11%) was obtained with 150 mumol kg-1 almagate. Administration of higher doses of almagate (200-250 mumol kg-1) did not result in any further increase in the level of protection against ethanol-induced gastric damage. Administration of 1 mL 100% ethanol induces substantial damage to the gastric mucosa, with nearly 40% of the length of the section evaluated exhibiting deep necrotic and haemorrhagic damage. Pretreatment with almagate caused a significant diminution in all parameters of histological damage, whereas damage to the epithelial cell layer was only significantly reduced by pretreatment with the highest doses evaluated (25, 50 and 150 mumol kg-1). Administration of aluminium hydroxide did not modify ethanol-induced mucosal damage, even at doses containing concentrations of aluminium higher than those present in gastroprotective doses of almagate. Pretreatment with sucralfate, another aluminium containing compound, at doses of 250 mumol kg-1 protected the mucosa, although lower doses did not. The present study has shown that almagate prevents ethanol-induced gastric mucosal damage.(ABSTRACT TRUNCATED AT 250 WORDS)

The vagus nerve and its non-cholinergic mechanism in the modulation of ethanol-induced gastric mucosal damage in rats.

The role of the cholinergic pathway in the vagus nerve in modulating gastric lesion formation by ethanol was examined, using an ex-vivo stomach chamber preparation. Subdiaphragmatic vagotomy significantly increased the lesion areas but lowered acid secretion and gastric mucosal blood flow (GMBF). Atropine had no effect, whereas pirenzepine antagonized ethanol-induced mucosal damage. All three procedures showed similar potencies in depressing acid secretion, but only pirenzepine reversed the fall in the GMBF produced by ethanol. These differential effects of vagotomy, atropine and pirenzepine on gastric function suggest that the cholinergic component in the vagus nerve may not be important in the formation of ethanol-induced gastric damage. The persistent protective action as well as the restoration of ethanol-induced GMBF drop by pirenzepine in vagotomized animals further support this hypothesis. The worsening effect of vagotomy is probably modulated by a non-cholinergic mechanism, the abolition of which makes the gastric mucosa more susceptible to damage by ethanol. The acid-independent protective action of pirenzepine and its influence on the GMBF, which were not exhibited by atropine, are indeed unique and perhaps may be attributed to this non-cholinergic pathway.

Regenerative Potential of Aqueous Extract of Neem Azadirachta indica on the Stomach and Ileum Following Ethanol-induced Mucosa Lesion in Adult Wistar Rats.

BackgroundThe aim of this study was to examine whether neem Azadirachta indica possesses regenerative potential on the stomach and ileum at 500 mg/kg dose given every 12 hours after mucosa lesion was brought by the administration of 1 ml of 50% ethanol for 21 consecutive days in adult Wistar rats.MethodsAdult male Wistar rats used in the study were divided into 3 groups: group A received oral normal saline and served as control; group B received 1.0 ml of 50% ethanol orally every 12 hours; and group C received neem extract (500 mg/kg) orally 12 hours after ethanol (50%, 1.0 ml) administration to verify its regenerative potential. The experiment lasted for 21 days after which the animals were sacrificed following chloroform inhalation and the stomach and ileum excised and processed for histological and morphometric examinations.ResultsEthanol treated rats showed marked gross mucosal lesions in the stomach and ileum. Ulcerated mucosa with marked apoptotic bodies and destruction of glandular elements were evident in the animals (group B). Neem extract administered 12 hours after the ethanol administration showed regenerative potential against ethanol-induced mucosal damage. This was characterized by mild restoration of the ulcerated mucosa epithelium and reorganization of the cyto-architechtural outline in group C.ConclusionsOur investigation suggests that neem extract has a regenerative potential and may be adopted in the management of gastrointestinal disorders such as ulcer.

Protective effects of DIDS against ethanol-induced gastric mucosal injury in rats

The compound 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) is an efficient anion exchanger inhibitor that can block the activities of anion exchanger 2 (AE2), which plays an indispensable role in gastric acid secretion. DIDS also has potent anti-oxidative and antiapoptosis activities. This study aimed to investigate the effect of DIDS on ethanol-induced mucosal damage in rats and to evaluate the underlying mechanisms that mediate the action of the compound. The rats received 1 ml of absolute ethanol or saline orally. DIDS [50 mg/kg intravenous (i.v.)] was given 5 min before ethanol administration. Gastric lesions were evaluated macroscopically, microscopically, and electron microscopically at 60 min after ethanol challenge. Gastric myeloperoxidase (MPO) activity, malonyldialdehyde (MDA) level, prostaglandin E2 (PGE2) synthesis, and cyclooxygenase-2 (COX-2) expression were assessed. For the evaluation of the effect of DIDS on gastric acid secretion, histamine-stimulatory gastric acid secretion was examined with or without pretreatment of DIDS (50 mg/kg; i.v.). Ethanol-induced gastric lesions were characterized by increasing gastric MDA level, MPO activity, and COX-2 expression, and decreasing PGE2 synthesis. It was found that DIDS significantly reduced the extent of gastric mucosal damage and reversed tissue MDA level and MPO activity. DIDS further enhanced the expression of COX-2 and reversed the decrease of PGE2. Our results suggested that DIDS is beneficial in rat model of gastric injury through mechanisms that involve inhibiting inflammatory cell infiltration and lipid peroxidation and up-regulating the COX-2/PGE2 pathway.

Nocistatin and nociceptin given centrally induce opioid-mediated gastric mucosal protection

Nociceptin (N/OFQ) and nocistatin (NST) are two endogenous neuropeptides derived from the same precursor protein, preproN/OFQ. The aim of the present work was to study the effect of NST on the ethanol-induced mucosal damage compared with that of N/OFQ following intracerebroventricular (i.c.v.) administration in the rat and to analyze the mechanism of the gastroprotective action. It was found that both NST and N/OFQ reduced the mucosal lesions in the same dose range (0.2–1 nmol i.c.v.), but in higher doses (2–5 nmol i.c.v.) the gastroprotective effect of both peptides was highly diminished. The gastroprotective effect of N/OFQ (1 nmol), but not that of NST (1 nmol), was reduced by the selective nociceptin receptor antagonist J-113397 (69 nmol i.c.v.). Similarly, decrease of the gastroprotective effect was observed after the combination of NST (1 nmol) with N/OFQ (0.6 or 1 nmol). However, addition of the gastroprotective effects was observed, when lower dose (0.2 nmol) of NST was given prior to N/OFQ (0.6 nmol). The gastroprotective effect of both N/OFQ and NST was antagonized by naloxone (27 nmol), β-funaltrexamine (20 nmol), naltrindole (5 nmol) and norbinaltorphimine (14 nmol), the μ-, δ- and κ-opioid receptor antagonists, respectively, given i.c.v. The mucosal protection was significantly decreased after bilateral cervical vagotomy. The present findings suggest that NST similar to N/OFQ, may also induce gastric mucosal protective action initiated centrally in a vagal-dependent mechanism. Opioid component is likely to be involved in the gastroprotective effect of both NST and N/OFQ.

Protective Effect of a Novel Rice Extract Against Ethanol-Induced Gastric Mucosal Injury in Rat

The aim of this study was to investigate the protective action of rice extract on ethanol-induced mucosal damage in vivo and wound healing of epithelial cells in vitro. Also, the effect of rice extract on gastric mucosal prostaglandin E(2) level, HSP72 expression, gastric acid secretion, and contribution of vanilloid receptor-mediated action was studied. In addition, using cultured gastric mucosal cells (RGM-1), the effect of rice extract on cytoprotection and wound healing of epithelial cells was evaluated. Rice extract significantly reduced gastric mucosal damage produced by ethanol in vivo, and heat treatment (80 degrees C, 3 min) of this agent did not alter its protective effect. Rice extract also protected RGM-1 from ethanol-induced damage in a dose-dependent manner. Rice extract accelerated wound healing of gastric epithelial cells. Our results demonstrate that rice extract could be an alternative ulcer treatment that provides cytoprotection and enhancement of wound healing not dependent on acid secretion, prostaglandin E(2) level, HSP72 expression, or vanilloid receptors.

Dose-Dependent Effects of Verapamil on Ethanol-Induced Gastric Lesions in Rats

The effects of graded doses of verapamil on ethanol-induced stomach mucosal damage were studied in rats. Gastric lesions were induced in vivo by oral administration of 80% ethanol and evaluated with regard to ulcer index, gastric mucus content, free and total acidity, lipid peroxidation and nonprotein sulfhydryl groups. Orally administered ethanol markedly increased the ulcer index and lipid peroxidation. Pretreatment of rats with verapamil (1, 5, and 25 mg/kg i.p.) was carried out 1 h before the administration of ethanol. Verapamil showed a protective effect against ethanol-induced mucosal damage only at high dose (25 mg/kg). Verapamil dose dependently decreased the total acidity, lipid peroxidation, and nonprotein sulfhydryl content. Verapamil 25 mg/kg also increased significantly the gastric mucus secretion. L-arginine (100 mg/kg) or L-nitroarginine (100 mg/kg) with verapamil were also administered to the animals to determine the role of nitric oxide in the mechanism of the gastroprotective activity of verapamil (25 mg/kg). The results indicate that reduced acidity and lipid peroxidation and increased mucus secretion participate in the protective effects of verapamil against ethanol damage. On the other hand, a decrease in the nonprotein sulfhydryl content was observed with decreased gastroprotective effects of verapamil.

Gyrus cinguli transection abolishes delta-opioid receptor-induced gastroprotection and alters alpha 2 adrenoceptor activity in the lower brainstem in rats

Previously, using the acidified ethanol-induced ulcer model in rats, we demonstrated that the mainly vagus-dependent gastroprotective effect of intracerebroventricularly injected clonidine was mediated by β-endorphin release in the lower brainstem. Presently, retroarcuate transections were used to evaluate the contribution of forebrain β-endorphinergic projection in this mechanism. Since the transection trajectory affected the cingulate cortex and other forebrain structures, matching lesions were also performed. In control and sham-operated rats intracisternal injection of clonidine and the direct opioid receptor (delta type) stimulant peptide ( d-Ala 2, d-Leu 5)-enkephalin caused a potent and fully naloxone-reversible (i.e. opioid receptor-mediated) protection against acidified ethanol-induced mucosal damage. In gyrus cinguli-transected rats (as well as in groups with midline hippocampal, thalamic and hypothalamic lesions) gastric mucosal protection induced centrally by direct delta-opioid receptor stimulation in the lower brainstem was completely abolished. The protective effect of clonidine was significantly reduced but it was still present in these animals. The residual protection by clonidine was naloxone-resistant, i.e. independent of an opioid mediation. Transections of the cingulate gyrus as well as thalamic but not the retroarcuate transections elevated plasma corticosterone levels. The changes seen in the clonidine/opioid-induced gastroprotection did not show any correlation with the changes in plasma corticosterone levels. It was concluded that (i) the transection of the cingulate cortex strongly influences the neural input to the nucleus tractus solitarii–dorsal motor vagal nucleus complex that is required for the activation of gastroprotective vagus outflow by delta-opioid receptor stimulation; (ii) the transection uncovers a direct, clonidine-induced gastroprotective pathway which is probably suppressed in intact animals.

Melatonin prevents ethanol-induced gastric mucosal damage possibly due to its antioxidant effect.

Oxygen radical release has been proposed as a pathogenic factor of the ethanol-induced acute gastric injury. Melatonin, a pineal hormone, is known to scavenge oxygen free radicals. We investigated whether parenteral administration of melatonin prevented ethanol-induced macroscopic damage, polymorphonuclear (PMN) leukocyte infiltration, depletion of total glutathione (tGSH) concentration, and glutathione reductase (GSSG-Rd) activity in the rat gastric mucosa. We compared the effects of melatonin with those of omeprazole. Ethanol-induced mucosal damage was evaluated using three different parameters: gastric total glutathione (tGSH) concentration and glutathione reductase (GSSG-Rd) activity, the number of PMN leukocytes, and macroscopic investigation. Gatric tGSH concentration and GSSG-Rd activity decreased and the number of PMNs increased after ethanol administration. It was found that pretreatment with melatonin increased both tGSH concentration and GSSG-Rd activity. Melatonin also reduced ethanol-induced PMN infiltration in the stomach. Ethanol administration damaged the entire gastric mucosa. Melatonin significantly decreased the extent of ethanol-induced macroscopic injury. In conclusion, these findings support the conclusion that the protection conferred by melatonin in gastric ulcer is presumably due to its antioxidant activity.

Antioxidant effect of T-type calcium channel blockers in gastric injury.

It is known that calcium ion has an important role in the cellular function. For this reason, calcium channel blockers may have a protective action against gastric injury which is induced by various stimuli. In this study, the influence of mibefradil on ethanol-induced gastric injury was investigated in rats. Mibefradil was given at a dose 50 mg/kg intraperitoneally 30 min before administration of 1 ml absolute ethanol given by gavage. We compared this effect of mibefradil with that of omeprazol. Ethanol-induced mucosal damage was evaluated using three different approaches: analysis of biochemical parameters and pathologic and macroscopic investigation. It was found that pretreatment with mibefradil significantly reduced ethanol-induced macroscopic, pathologic, and biochemical changes in the gastric mucosa. In conclusion, it is speculated that this findings may prove important in the development of new and improved therapies for the treatment and prevention of gastric ulcers in humans.

Ethanol-induced mucosal damage does not increase formation of prostaglandin D2 in the rat stomach

Ethanol-induced mucosal damage does not increase formation of prostaglandin D2 in the rat stomach

Ethanol-induced mucosal damage does not increase formation of prostaglandin D2 in the rat stomach

Ethanol-induced mucosal damage does not increase formation of prostaglandin D2 in the rat stomach

Adaptive Cytoprotection Mediated by Prostaglandin I2 Is Attributable to Sensitization of CGRP-Containing Sensory Nerves

The phenomenon by which the gastric mucosa is protected in response to mild irritants has been called adaptive cytoprotection, a mechanism believed to be related to production of endogenous prostaglandins (PGs). We tested whether PGs generated by mild irritant prevent injury through the release of calcitonin gene-related peptide (CGRP) from the sensory nerves using prostanoid receptor-knockout mice. The stomach was doubly cannulated and perfused with 1 mol/L NaCl or 50% ethanol. CGRP levels in the perfusate were determined by enzyme immunoassay, and the injured area was estimated at the end of perfusion. Preperfusion with mildly hypertonic saline (1 mol/L NaCl) increased generation of gastric PGE(2) and PGI(2) and reduced ethanol-induced mucosal damage. Exposure of ethanol after 1 mol/L NaCl increased intragastric CGRP levels from 166 +/- 27 to 713 +/- 55 pg/2 min (n = 4, P < 0.05), and the protective action of 1 mol/L NaCl was inhibited by indomethacin treatment. CGRP antagonist blocked 1 mol/L NaCl-induced protective effect. Intragastric perfusion of 50% ethanol after administration of PGI(2), but not of PGE(2), increased CGRP levels. Application of 1 mol/L NaCl to IP receptor-knockout mice (IP(-/-)) did not elicit the protective effects seen in the wild-type on ethanol-induced gastric mucosal lesions. Protective effect of 1 mol/L NaCl was observed in EP3 receptor-knockout mice (EP3(-/-)). CGRP level during ethanol perfusion was not increased in IP(-/-) but was increased in EP3(-/-) and wild-type counterparts after preperfusion of 1 mol/L NaCl. These results indicate that the endogenous PGI(2) generated by 1 mol/L NaCl may have a protective role in gastric mucosal injury through enhancement of CGRP release from gastric mucosa. This mechanism may explain the adaptive cytoprotection observed after treatment with mild irritants.

Alpha-2 adrenergic and opioid receptor-mediated gastroprotection

Clonidine inhibited the development of gastric mucosal lesions induced by either acidified ethanol or indomethacin. The ED 50 values were: 7.1 and 5.2 μg.kg –1 orally, respectively. The gastroprotective effect was antagonised by the pre-synaptic alpha-2 antagonist yohimbine, the more selective alpha-2 antagonist Ch-38083 and the pre-synaptic alpha-2B antagonist prazosin. Moreover, the non-selective opioid receptor antagonist naloxone, the delta receptor selective naltrindole also reversed the clonidine-induced mucosal protective action. Clonidine was also effective following intracerebroventricular administration with the ED 50 of 37 ng/rat against ethanol-induced mucosal damage. Our results suggest that: 1) the gastroprotective effect of clonidine is likely to be mediated by alpha-2B adrenoceptor subtype; 2) there is an interaction between pre-synaptic alpha-2 adrenoceptors and opioid system; and 3) clonidine can induce gastroprotection by central mechanism.

Selective cyclo-oxygenase-2 inhibitors aggravate ischaemia-reperfusion injury in the rat stomach.

1. Effects of indomethacin, the selective cyclo-oxygenase (COX)-2 inhibitors NS-398 and DFU, and dexamethasone on gastric damage induced by 30 min ischaemia followed by 60 min reperfusion (I-R) were investigated in rats. Modulation of gastric levels of COX-1 and COX-2 mRNA by I-R was evaluated using Northern blot and reverse transcription-polymerase chain reaction. 2. I-R-induced gastric damage was dose-dependently aggravated by administration of indomethacin (1 - 10 mg kg(-1)), NS-398 (0.4 - 4 mg kg(-1)) or DFU (0.02 - 2 mg kg(-1)) as assessed macroscopically and histologically. 3. Likewise, administration of dexamethasone (1 mg kg(-1)) significantly increased I-R damage. 4. Low doses of 16, 16-dimethyl-prostaglandin(PG)E(2), that did not protect against ethanol-induced mucosal damage, reversed the effects of the selective COX-2 inhibitors, indomethacin and dexamethasone. 5. I-R had no effect on gastric COX-1 mRNA levels but increased COX-2 mRNA levels in a time-dependent manner. Dexamethasone inhibited the I-R-induced expression of COX-2 mRNA. 6. I-R was not associated with a measurable increase in gastric mucosal formation of 6-keto-PGF(1alpha) and PGE(2). PG formation was substantially inhibited by indomethacin (10 mg kg(-1)) but was not significantly reduced by NS-398 (4 mg kg(-1)), DFU (2 mg kg(-1)) or dexamethasone (1 mg kg(-1)). 7. The findings indicate that selective COX-2 inhibitors and dexamethasone markedly enhance gastric damage induced by I-R. Thus, whereas COX-2 has no essential role in the maintenance of gastric mucosal integrity under basal conditions, COX-2 is rapidly induced in a pro-ulcerogenic setting and contributes to mucosal defence by minimizing injury. This suggests that in certain situations selective COX-2 inhibitors may have gastrotoxic effects.

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

The correlation between mucosal generation of nitric oxide (NO) and prostaglandin E2 (PGE2) in gastric adaptive cytoprotection was investigated. 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. Macroscopic gastric mucosal damage, NO synthase activity, mucosal PGE2 and leukotriene C4 (LTC4) levels were measured. 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. 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.

Effect of Age and Weaning on Gastric Mucosal Injury in Developing Rats

We evaluated ethanol- and HCl-induced mucosal damages in developing rats. The degree of damage induced by ethanol and HCl was greatest in 1-week-old rats and decreased significantly with age until 4 weeks; thereafter it increased again. To evaluate the effect of weaning on the maturational changes in mucosal defense, we compared ethanol-induced mucosal damage among three groups of newborn rats: (1) receiving milk only; (2) receiving only rat chow from 14 days of age, and (3) having free access to milk and chow. There were no significant differences at 18 and 21 days of age. The mucus thickness increased with age until 8 weeks and was not affected by weaning. In conclusion, developmental changes occur in gastric mucosal protection in rats. Weaning does not have a significant effect on these changes.

Histological study of mechanisms of adaptive cytoprotection on ethanol-induced mucosal damage in rat stomachs.

Adaptive cytoprotection in the gastric mucosa could be induced by exposure to low concentrations of noxious agents. However, experimental results reported so far were based on macroscopic studies. We aimed to investigate the phenomenon of gastric adaptive cytoprotection of mild irritants and its correlation with intramucosal mucus at the histological level. It was found that histological damage induced by ethanol had a negative correlation with the length of the mucus-secreting layer in the gastric mucosa. Mild irritants such as 20% ethanol and 5% NaCl preserved the 100% ethanol-induced intramucosal mucus depletion, but only the former agent demonstrated a cytoprotective effect against the histological damage, indicating that preservation of intramucosal mucus may not necessarily play a permissive role in adaptive cytoprotection. The capsaicin-sensitive sensory afferent neurons, sensory chemoreceptors, muscarinic receptors, alpha2-adrenoceptors and peripheral dopamine D2-receptors were found to be the components of the autonomic nervous system involved in the cytoprotective processes of 20% ethanol. Endogenous mediators including nitric oxide, prostaglandins, and possibly nonprotein sulfhydryl compounds also seemed to participate in such protection. Nevertheless, 0.3 M HCl did not show any effect either on mucosal damage or depletion of intramucosal mucus induced by absolute ethanol. These findings suggest that only 20% ethanol shows histological cytoprotection, which would involve various components of the autonomic nervous system and endogenous mediators. Furthermore, this investigation also implies a new perspective: that in order to study a true adaptive cytoprotection, histological examination of the gastric mucosa should be performed.

Gastric mucosal apoptosis induced by ethanol: effect of antiulcer agents.

In this study, we investigated gastric epithelial cells' apoptosis and tumor necrosis factor-alpha (TNF-alpha) expression with ethanol-induced mucosal injury, and the effect of antiulcer agents on this process. Rats received intragastric pretreatment with the agent or vehicle followed 1h later by ethanol, and after 30 min the gastric mucosa was assessed for TNF-alpha and apoptosis. In the absence of antiulcer agents, ethanol caused extensive mucosal lesions accompanied by a 9.5-fold enhancement in apoptosis and a 2.5-fold increase in TNF-alpha. Pretreatment with omeprazole evoked a 54% reduction in TNF-alpha, but had no effect on ethanol-induced mucosal damage or apoptosis, the sucralfate reduced the extent of mucosal damage by 95%, apoptosis by 39% and TNF-alpha by 52%, while ebrotidine not only prevented mucosal injury and rise in TNF-alpha, but also caused a 70% reduction in epithelial cells' apoptosis. The results demonstrate that ethanol-induced gastric epithelial cells apoptosis triggered by the enhancement in mucosal TNF-alpha is efficiently counteracted by ebrotidine.