Effects of ethanol on the gastric mucosa of the Heidenhain pouch of dogs

Association between the consumption of ultra-processed foods and the incidence of peptic ulcer disease in the SUN project: a Spanish prospective cohort study

PURPOSE

Consumption of ultra-processed foods (UPF) has increased despite potential adverse health effects. Recent studies showed an association between UPF consumption and some gastrointestinal disorders. We evaluated the association between UPF consumption and peptic ulcer disease (PUD) in a large Spanish cohort.

METHODS

We conducted a prospective analysis of 18,066 participants in the SUN cohort, followed every two years. UPF was assessed at baseline and 10 years after. Cases of PUD were identified among participants reporting a physician-made diagnosis of PUD during follow-ups. Cases were only partially validated against medical records. Cox regression was used to assess the association between baseline UPF consumption and PUD risk. Based on previous findings and biological plausibility, socio-demographic and lifestyle variables, BMI, energy intake, Helicobacter pylori infection, gastrointestinal disorders, aspirin and analgesic use, and alcohol and coffee consumption were included as confounders.We fitted GEE with repeated dietary measurements at baseline and after 10 years of follow-up. Vanderweele's proposed E value was calculated to assess the sensitivity of observed associations to uncontrolled confounding.

RESULTS

During a median follow-up of 12.2 years, we recorded 322 new PUD cases (1.56 cases/1000 person-years). Participants in the highest baseline tertile of UPF consumption had an increased PUD risk compared to participants in the lowest tertile (HR = 1.52, 95% CI: 1.15, 2.00, Ptrend=0.002). The E-values for the point estimate supported the observed association. The OR using repeated measurements of UPF intake was 1.39 (95% CI: 1.03, 1.87) when comparing extreme tertiles.

CONCLUSION

The consumption of UPF is associated with an increased PUD risk.

Nutrients affecting gastric barrier

The gastric barrier could be considered an active tissue involved in many synthetic and metabolic functions, as the immunological defense, by activating mucosal immune system. Barrier integrity results from a balance between protective and aggressive endogenous factors and from their interaction with exogenous factors (steroidal or nonsteroidal anti-inflammatory drugs, dietary nitrates, nitrites and/or NaCl, stress, Helicobacter pylori infection, food allergens and contaminants, metals, chemicals, radiation, smoking and alcohol intake). Nutrients represent the most important exogenous factors affecting gastric barrier because of the impact on people's everyday life. We report evidence from the literature about nutrients affecting gastric barrier and we investigate the possible effect that nutrients can play to determining or maintaining a gastric barrier dysfunction.

Alcohol-related diarrhea

Abstract Alcohol generates a large caloric yield without supplying any essential nutrients; alcoholics may thus maintain body weight while suffering from malnutrition. In addition, diarrhea is a common complaint of both acute and chronic alcoholics. Here, we review the effects of alcohol on gastrointestinal morphology, function, its nervous system and motility. Acute morphological changes such as erosions, inflammatory cell infiltrations and microvascular changes are seen in the stomach and small intestine in acute alcoholics. In addition, atrophic gastritis, reduced villous height and decreased mucosal surface area of the small intestine have been described in chronic alcoholics. Acute administration of alcohol inhibits absorption of nutrients and fluids, and can stimulate secretion of water and electrolytes. Bacterial overgrowth in the proximal small intestine and decreased pancreatic secretions have been also described in chronic alcoholics. The well-known deleterious effects of alcohol on the central nervous system raise the possibility of similar acute and chronic effects of the enteric nervous system. Such effects could alter motility and transit. Indeed, esophageal dysmotility and delayed gastric emptying have been observed with high concentrations of alcohol in experimental studies and in chronic alcoholics. Small bowel motility and transit may be abnormal in both acute and chronic alcoholics, and colonic propulsive motility is increased after acute administration of alcohol. Any, or all, of these changes in gastrointestinal functions may contribute to diarrhea in acute binge drinkers and chronic alcoholics. Unfortunately, there is a lack of systematic studies of the pathophysiology of alcohol abuse, and an integrating concept of the diarrhea of alcoholics is still not possible.

Ethanol, its effect on the synthesis of proteins by guinea-pig gastric mucosa

Incorporation of L-[U-14C]leucine into proteins is taken to indicate the synthesis of proteins by guinea pig gastric mucosa. Ethanol reduced the synthesis of proteins in vitro by homogenized mucosa, by isolated gastric epithelial cell preparations and by intact tissue. Intact stomach wall incubated without ethanol in phosphate buffered saline showed progressively increasing incorporation of the precursor into tissue proteins and into proteins which were secreted into the mucosal incubation media. On isopycnic CsCl gradient fractionation radioactive tissue proteins were found at the top of the gradient (fraction L1, sp.gr.1.11-1.20) while radioactive secreted proteins sedimented to the bottom of the gradient as the carbohydrate rich high density gastric mucosal glycoprotein fraction L3 (sp.gr.1.29-1.33). Ethanol significantly but reversibly reduced the incorporation of radioactive leucine by intact mucosa into both the tissue proteins and the secreted proteins. Uptake of the precursor into the intracellular acid soluble pool was not impaired by ethanol and no significant differences were detected in the specific activities of free intracellular leucine between the ethanol treated samples and the corresponding controls. It is suggested that the ulcerogenic nature of ethanol may be associated with inhibition of the synthesis of proteins within mucosal epithelium leading to reduction in the output of mucosal secretory glycoproteins with subsequent impairment of the cytoprotective properties of the dynamic mucous barrier.

Recovery of rat gastric mucosa following single fluoride dosing

Rats' stomachs were intubated with 0.1 N HCl or 100 mM NaF in 0.1 N HCl and excised after 1, 12, 24, 48 h or 7 days for light microscopy. The NaF solution caused erosive injury to the oxyntic glandular mucosa 1 h after application. Progressive stages of recovery were seen at 12, 24 and 48 h after fluoride dosing. Complete recovery was seen 7 days after exposure to fluoride. The kinetics of the recovery process from fluoride injury appear to be similar to those which have been reported for gastric injury produced by other substances.

Prostaglandins and histological changes in the gastric mucosa

Gastric 'cytoprotection' was originally defined as the prostaglandin (PG)-mediated absence of grossly visible necrotic lesions produced by any of several necrotizing agents. It was assumed that the absence of necrotic lesions was synonymous with an undamaged mucosa. Subsequent microscopic analysis showed that PG did not protect the superficial gastric epithelium against damage by a necrotizing agent and absolute ethanol. Necrotizing agents such as absolute ethanol appear to produce two major types of damage in vivo: (i) superficial damage, which is confined to the interfoveolar, gastric pit and sometimes upper gastric glands and is not accompanied by significant hemorrhage; (ii) necrotic lesions, which are focal regions of vascular stasis, hemorrhage and associated cellular necrosis extending deep within the mucosa. PG pretreatment largely prevents the formation of necrotic lesions (but does lessen the severity of) the superficial damage. Necrotic lesions heal slowly over a period of days to months whereas superficial damage in vivo heals within approximately 60 minutes by the rapid migration of mucous cells from the gastric pit and isthmus of the oxyntic gland. Exogenous PG elicits a thicker mucus gel which has been implicated in cytoprotection. Experimental evidence now suggests that mucus may have an important role in preventing further damage, after the initial insult, by forming a cap or gelatinous layer over the injured regions. In toto these studies demonstrate three additional protective mechanisms of the superficially injured gastric mucosa: (i) a shielding gelatinous layer formed of mucus and exfoliated surface epithelial cells which forms a barrier to substances in the lumen and traps an alkaline fluid next to the healing surface; (ii) a flow of alkaline mucosal fluid into the lumen which dilutes noxious agents there and helps provide an optimum healing environment at the injured surface; (iii) a rapidly healing superficial mucosal layer which quickly reinstates the physical barrier between the gastric lumen and lamina propria. It is concluded that although PGs do not protect the superficial gastric epithelium against damage by a necrotizing agent, PGs markedly lessen the severity of damage primarily by preventing hemorrhagic lesions.

A fluorescent in vivo microscopic method to assess surface mucosal integrity in the rat stomach. Effects of ethanol and prostaglandin

A new sensitive in vivo fluorescent method to assess gastric mucosal integrity in the anesthetized rat is described. Topically applied fluorescein diacetate enters gastric mucosal cells. The diacetate is cleaved by intracellular esterases leaving fluorescein trapped within the cells. The pattern of fluorescence can be visualized, and the intensity of fluorescence measured, using a fluorescent in vivo microscopy system. Frozen section studies revealed that fluorescein was located in the surface mucous cells and the mucous neck cells. Topically applied ethanol caused a dose-dependent decline in intensity of fluorescence. Measurement of fluorescence in the supernatant bathing the mucosa revealed that leak of fluorescein out of cells or shedding of cells was, at least in part, responsible for the decline in fluorescence intensity. Pretreatment with a "cytoprotective" dose of 16,16-dimethyl prostaglandin E2 did not protect against the decline in fluorescence seen after 12.5% and 25% ethanol. This confirms findings of previous histologic studies that prostaglandin "cytoprotection" does not include surface cell protection. We conclude that this technique provides a sensitive, quantitative in vivo method to study gastric surface cell injury.

Gastric mucosal resistance to a repeated ethanol insult

The luminal gastric mucosa of anesthetised rats was uniformly exposed to 70% ethanol for 30-45 seconds. Ninety-six per cent of the superficial epithelium was immediately destroyed. The mucosa was allowed to heal for 60 minutes, during which time 85% of the superficial mucosa had re-epithelialised. A thick gelatinous layer of necrotic cells and mucosal exudate formed over the restituted epithelium. To determine whether the mucosa could withstand a second ethanol insult, the same stomachs were re-exposed to 70% ethanol for 30-45 seconds and fixed for quantitative light microscopy. Significant damage to the newly formed epithelium was observed only when the gelatinous layer was first removed and then followed by a second ethanol insult. This resulted in uniform superficial damage to 92% of the mucosal surface with accompanying vascular stasis.

Effect of acute ethanol administration on diamine oxidase activity in the upper gastrointestinal tract of rat

The effect of a single dose (2 g/kg, body weight) of ethanol on diamine oxidase activity of the upper gastrointestinal tract was studied in fasted rats. Ethanol given by gastric intubation as a 10%, 20%, or 40% solution caused an early and transient increase in diamine oxidase activity in gastroduodenal fluid that was concentration-dependent. The 20% ethanol solution caused, at 3 and 6 hr, a diminution of enzyme activity in the wall of the stomach and duodenum, but not in that of the jejunum. Diamine oxidase activity in the gastroduodenal tract returned to control values at 12 hr, when ethanol had disappeared from the blood. The plasma enzyme activity diminished, starting from the first hour. The same dose of ethanol administered intravenously caused diminutions in diamine oxidase activity in the stomach and duodenum similar to those observed after gastric intubation. The enzyme decrease in the stomach and duodenum was not correlated with the gastroduodenal or blood ethanol levels. Pretreatment with pyrazole, an inhibitor of ethanol metabolism, prevented the ethanol-induced decrease in gastroduodenal enzyme activity, thus suggesting that this diminution was principally a consequence of ethanol oxidation. These results indicate that ethanol modifies in the gastroduodenal tract the activity of diamine oxidase the enzyme which regulates the physiologic activity of histamine in gastric secretion and oxidizes the toxic diamines of dietary and bacterial origin.

Alcohol and the gastrointestinal tract

The effects of acute and chronic ethanol ingestion on esophageal motility and the potential complications of these alterations are reviewed. Injury to the gastric mucosa and the small intestine and alterations in intestinal absorption can also result from alcohol abuse.

The roles of ethanol and of acid in the production of gastric mucosal erosions in rats

This study was undertaken to differentiate between the morphological changes produced in chambered rat gastric mucosae by 40% ethanol and by 50 mM HCl. 40% ethanol produced both focal mucosal hyperemia and widespread exfoliation of the surface epithelium. Massive release of mucus accompanied both events. In the absence of acid the released mucus was stabilized by a network of fibrin, and epithelial continuity was re-established over non-hyperemic regions by migration of epithelial (and parietal) cells from the gastric pits. Hemorrhagic erosions occurred only in the presence of acid, but were limited to the hyperemic regions. Acid had the following effects: (1) platelet thrombi were destroyed, thus promoting hemorrhage; (2) destruction of the fibrin network by acid caused dissipation of the adherent mucous coat; (3) vulnerable cells which had previously shown only ischemic damage were irreversibly damaged by acid; (4) exposed basal lamina was destroyed, thus removing the substratum necessary for orderly epithelial re-establishment.

Effects of alcohol on the pyloric sphincter

The effects of an intoxicating dose of alcohol (79 g of 100 proof alcohol) on pyloric sphincter function were studied in 12 normal subjects using an infused manometric system. Alcohol had no effect on resting pyloric sphincter pressure. Intraduodenal administration of olive oil and hypertonic amino acids increased pyloric sphincter pressure significantly to 10.8 +/- 1.4 and 10.2 +/- 2.0 mm Hg, respectively. These responses were not affected by the administration of alcohol. In contrast, alcohol decreased the pyloric pressure response to duodenal acidification from 12.0 +/- 2.1 to 8.0 +/- 1.3 mm Hg (P less than 0.05). These results suggest that an intoxicating dose of alcohol may interfere with the normal function of the pyloric sphincter.

Physiological and morphological characteristics of progressive disruption of the canine gastric mucosal barrier

The investigation had two major goals: to define the progression of physiological changes associated with disruption of the gastric mucosal barrier to sodium and hydrogen and to identify the morphological correlates of the physiological alterations. Fluxes of ions and water were determined before and after treatment of oxyntic mucosa with graded concentrations of butyric acid using dogs with gastric pouches. Three phases of barrier disruption were characterized: I, acceleration of normal Na+/H+ exchange; II, neutralization of H+; III, exudation of interstitial fluid. Parallel studies assessed morphological damage associated with these phases. In Phase I, cellular bulging into the lumen and dilation of intercellular spaces were evident. Some cellular erosion and extreme intercellular dilation were prominent in Phase II. Phase III was represented by necrotic changes and desquamation. It is concluded that disruption of transport mechanisms occurs sequentially and is closely correlated with morphological signs of progressive damage.

Effects of ethanol on plasma protein shedding in the human stomach

Plasma protein shedding in the stomach was measured in 23 normal individuals before and after intragastric administration of a 30% solution of ethyl alcohol. Two different methods were used to assess plasma protein shedding. The first technique utilizes [131I]albumin and requires neutralization of the gastric juice. It was used in 12 subjects and failed to demonstrate any increase of plasma protein shedding under the influence of ethanol. The second technique which utilizes [51Cr]chloride was used in 11 subjects. It demonstrated a significant increase of the gastric clearance of plasma protein which reached 2.5 times the control values. The [51Cr]chloride technique does not require prior neutralization of gastric acidity. It is concluded that, in normal man, ethanol administration increases plasma protein shedding in the stomach when it is given in the presence of an acid gastric juice. The effect is not observed when the gastric acidity is neutralized.

Ultrastructural changes of the canine gastric mucosa after topical application of graded concentrations of ethanol

Changes in the fine structure of the gastric mucosa following exposure to graded concentrations of ethanol were studied in dogs. 300 ml of 12.5, 20, and 40%, vol/vol, were instilled intragastrically for 30 min. Mucosa from the midbody and midantrum along the greater curvature was examined by light and electron microscopy. Ethanol produced a gradation of changes in the surface epithelial cells and in the lamina propria without affecting the parietal cells and chief cells. 12.5% ethanol produced widened and irregular intercellular spaces while 20 and 40% disrupted the apical cell membrane with concomitant exudation of mucin into the gastric lumen. These changes were more severe after 40% ethanol. The tight junction between cells remained intact following exposure to the lower concentrations of ethanol, but focal separation of cell junctions was observed in severely damaged areas. Quantitation of protein, sodium, and potassium concentrations in the gastric contents revealed marked increases following exposure to ethanol which correlated with the concentration. These studies provide additional morphological data on the relationship between structural changes and functional abnormalities induced by agents which break the gastric mucosal barrier.

Changes in mucosal and venous histamine concentrations during instillation of ethanol in the canine stomach

Histamine concentrations in the gastric mucosa, gastric vein blood, and gastric contents were measured after instillation of 300 ml of 40%, 20% and 12.5%, vol/vol, ethanol intragastrically for 30 min in anesthetized dogs. The mean histamine concentration in the gastric mucosa, gastric vein blood, and gastric contents in dogs treated with 40% ethanol was significantly higher than in dogs treated with sodium chloride (NaCl). Serial studies of the gastric vein blood of the ethanol-treated dogs should significant elevation of histamine concentrations for 2 hr after instillation of 40% ethanol, but less increases at 20 and 30 min after instillation of 12.5% and 20%, respectively. No change was observed after administration of 50% glucose and 25% mannitol. Morphologically, the gastric mucosa of the ethanol-treated dogs was edematous, congested and hemorrhagic. The severity of these changes increased with the concentration used. The mucosa of the dogs treated with sodium chloride, glucose, or mannitol was normal. The factors that may underlie the increase in histamine concentrations in the gastric vein blood and the possible relation of such an increase to the morphologic alterations are discussed.

Effects of ethanol on the secretion and mucosal blood flow of a denervated gastric pouch in the dog

Mucosal secretion and blood flow of a Heidenhain pouch were measured in dogs after orally administered ethanol at doses from 0.25 to 2 g/kg of body weight. Under these conditions, the volume, free and total acidity of the gastric juice as well as mucosal blood flow increased linearly with the dose up to 1 g/kg. In all cases volume secreted and acidity chanm the other parameters and could not be correlated with blood flow. The influence of gastrin and the modification of membrane permeability are discussed with regard to these data.

Alcohol injury to gastric mucosa in mice and its potentiation by stress

This investigation was initiated to separately evaluate the roles of dose and concentration of ethanol ingestion in the development of acute gastric mucosal injury and to determine the significance of stress as a potentiating factor in ethanol damage. A total of 423 mice were used in this study. Alcohol at the low concentration of 10% and at any of the doses used (1-5 g/kh wt) did not cause gastric mucosal lesions. Similarly, alcohol at the low dose of 1 g/kg wt at any of the concentrations used (10-50%) did not produce any gross injury to the stomach. A single oral administration of ethanol, given at doses of 2-5 g/kg wt and at concentrations of 25-50%, resulted in hyperemia and multiple fundic erosions and, less frequently, antral erosion. The incidence, number, and severity of these lesions rapidly increased with increase in ethanol concentration, ethanol dose, or both. Healing was rapid; at best, lesions were only barely visible 72 hours after alcohol ingestion. Repeated daily doses of ethanol given for 3-5 days did not increase the incidence and number of lesions, probably due to their capacity for rapid healing. Mild stress, in the form of 1-hour restraint in the cold room at 8 degrees C, by itself caused very little mucosal injury in mice, but significantly potentiated the injurious effect of 35% ethanol administered in a 3 g/kh dose. Stress following alcohol intake potentiated gastric mucosal injury much more than if the stress preceded the alcohol ingestion. The incidence, number, and severity of erosions was here 3,4 and 11 times, respectively, greater than the additive effect of alcohol and stress together (P smaller than 0.001). Thus, the extent of ethanol damage to the stomach related both to the concentration and dose of ethanol infested. Stress, especially when following excessive ethanol intake, was a highly significant factor in the potentiation of acute alcoholic gastric mucosal injury.

Gastric mucosal morphology and faecal blood loss during ethanol ingestion

The faecal blood loss of six alcoholic subjects with normal gastric mucosa, six with superficial gastritis, and six with atrophic gastritis was studied before and during ingestion of 40% v/v ethanol using (51)Cr-tagged red blood cells. No significant change in faecal blood loss was observed in the normal mucosa and superficial gastritis groups but all subjects with atrophic gastritis had significant increases of faecal blood loss during ethanol ingestion. These observations suggest that gastric mucosal morphology may be an important determinant of gastric mucosal bleeding during the ingestion of alcohol.