The mechanisms of the inhibitory effect of ethanol on gastric emptying involve type A CCK receptors

Chronic alcohol consumption affects gastrointestinal motility and reduces the proportion of neuronal NOS-immunoreactive myenteric neurons in the murine jejunum

Alcohol consumption interferes with gastrointestinal transit causing symptoms in alcoholic patients. Nitric oxide (NO), synthesized by neuronal nitric oxide synthase (nNOS) plays an important role in the control of gastrointestinal motility. Our aim was to investigate whether chronic alcohol intake in a murine model induces gastrointestinal motility disturbances and affects the nitrergic myenteric neurons in the stomach and jejunum. Gastric emptying, small intestinal transit and geometric centre were measured in vivo after intragastric gavage of Evans blue. Nitrergic relaxations to electrical field stimulation (EFS) and exogenous NO were recorded in jejunal muscle strips in vitro. The proportion of nNOS-immunopositive myenteric neurons was assessed using PGP9.5 and nNOS immunostaining. After chronic alcohol consumption, gastric emptying and small intestinal transit were delayed compared with control mice, and the nitrergic nerve-mediated relaxations to EFS in the jejunum were decreased, whereas relaxations to exogenous NO did not differ. The proportion of nNOS-immunoreactive neurons did not change in the stomach, whereas in the jejunum the percentage decreased from 33% to 27% (P < 0.001) after chronic alcohol intake. The total number of myenteric neurons remained unchanged. These results suggest that chronic alcohol consumption disturbs gastric and small intestinal motility in vivo and in vitro and is associated with a decrease in the proportion of nNOS-immunoreactive myenteric neurons in the murine jejunum.

Esomeprazole reduces gastroesophageal reflux after beer consumption in healthy volunteers

OBJECTIVE

Patients with gastroesophageal reflux disease (GERD) are advised to avoid alcoholic beverages since alcohol consumption induces gastroesophageal reflux in healthy volunteers and increases it in patients with GERD. Proton-pump inhibitors (PPIs) are frequently administered for reflux symptoms but their effect on gastroesophageal reflux after alcohol consumption has not yet been fully studied. The aim of the present study was therefore to investigate the effect of esomeprazole, an S-enantiomer of omeprazole, on gastroesophageal reflux after beer consumption.

MATERIAL AND METHODS

In this placebo-controlled, double-blind, crossover study, 16 healthy male volunteers received 20 mg esomeprazole daily for one week. On day 7, in an acute experiment, the subjects then consumed 500 ml beer within 5 min. Subsequently, gastroesophageal reflux was monitored by pH-metry over a period of 3 h. In addition, gastric emptying was measured by ultrasonography and blood concentrations of ethanol, cholecystokinin and gastrin were determined.

RESULTS

Gastroesophageal reflux was significantly (p=0.001) reduced by 93% after treatment with esomeprazole (0.2%, median percentage of time pH<4) as compared to placebo (2.6%), but gastric emptying, blood ethanol and cholecystokinin concentrations were not significantly different after esomeprazole treatment. Plasma gastrin levels were significantly (p=0.0003) higher after esomeprazole (98.6+/-19.7 pg/ml) than after placebo (22.7+/-3.8 pg/ml) before beer consumption. However, there was no difference in the increase in plasma gastrin after beer consumption between the esomeprazole treatment and placebo.

CONCLUSIONS

Esomeprazole significantly reduces gastroesophageal reflux after beer consumption in healthy volunteers. Gastric emptying of beer is not prolonged after treatment with esomeprazole, although compared with placebo, this PPI induced significantly higher plasma gastrin concentrations. Moderate alcohol consumption does not worsen gastroesophageal reflux when a PPI is administered.

Physical and biological considerations for the use of nonaqueous solvents in oral bioavailability enhancement

This review addresses the use of nonaqueous solvents as components of oral formulations in discovery and preclinical studies. Pharmacology, pharmacokinetic, and safety studies are frequently conducted with solution formulations that use a solvent to solubilize poorly aqueous soluble drugs. The physical chemical basis for solubilization and the precipitation of solubilized drug following administration both contribute to the utility of nonaqueous solvent solutions as oral vehicles. While many of these solvents are considered nontoxic, they are not completely inert biologically. The effects of common nonaqueous solvents on the structural integrity of the epithelia, the inherent permeability of and flux across the GI membrane, the activity of efflux and metabolic enzymes, and the effects on GI motility and GI transit times will be described through an examination of available literature. The practical relevance of these factors to the development of early formulations will be examined critically and suggestions made for the suitability of nonaqueous solvents for a variety of purposes.

Animal models and their results in gastrointestinal alcohol research

Alcohol-induced diseases of the gastrointestinal tract play an important role in clinical gastroenterology. However, the precise pathophysiological mechanisms are still largely unknown. Alcohol research depends essentially on animal models due to the fact that controlled experimental studies of ethanol-induced diseases in humans are unethical. Animal models have already been successfully applied to disclose and analyze molecular mechanisms in alcohol-induced diseases, partially by using knockout technology. Because of a lack of transferability of some animal models to the human condition, results have to be interpreted cautiously. For some alcohol-related diseases like chronic alcoholic pancreatitis, the ideal animal model does not yet exist. Here we provide an overview of the most commonly used animal models in gastrointestinal alcohol research. We will also briefly discuss the findings based on animal models as well as the current concepts of pathophysiological mechanisms involved in acute and chronic alcoholic damage of the esophagus, stomach, small and large intestine, pancreas and liver.

Exogeneous and endogenous CCK inhibit ethanol ingestion in Sardinian alcohol-preferring rats

Ethanol ingestion, like food ingestion, stimulates release of the signaling molecule cholecystokinin (CCK) from the small intestine. Here, we investigated the possibility that ethanol-induced CCK release might be a negative-feedback control of ethanol ingestion, similar to its function as part of the mechanism by which ingested food produces meal-ending satiation. We used Sardinian alcohol-preferring (sP) and Marchesian Sardinian (msP) alcohol-preferring rats, two apparently identical substrains that spontaneously ingest pharmacologically relevant amounts of ethanol, as well as their background strain, Wistar (W) rats. We demonstrated that: (1) intraperitoneal (IP), but not intracerebroventricular, injections of 0.5-4 microg/kg CCK-8 produced transient, dose-related reductions in 10% ethanol ingestion; (2) this inhibitory effect of CCK-8 on ethanol intake appeared behaviorally similar to its inhibitory action on ingestion of sucrose solutions; (3) the inhibitory effect of IP CCK-8 on ethanol ingestion occurred without evidence of tolerance when tests were repeated on consecutive days; (4) IP CCK-8 reduced ethanol intake despite simultaneously reducing blood ethanol levels (BALs); and (5) antagonism of CCK1 receptors with devazepide increased ethanol intake, indicating that endogenous CCK normally limits the size of bouts of ethanol ingestion. These results implicate peripheral CCK in the control of ethanol ingestion in sP and msP alcohol-preferring rats.