Protective effect of mannitol, glucose-fructose-sucrose-maltose mixture, and natural honey hyperosmolar solutions against ethanol-induced gastric mucosal damage in rats.

BACKGROUND: We have previously shown that natural honey is able to protect the rat stomach against acute ethanol- and indomethacin-induced lesions. The present investigations were undertaken to examine the role of intraluminal osmolality in this protective effect. METHODS: Mannitol, glucose-fructose-sucrose-maltose mixture (GFSM) and natural honey (300, 600, 1800 mOsmol/kg water) were given orally to rats 30 min before administration of 70% ethanol for a further 15-min period. Lesions area of the excised stomachs were evaluated. Pylorus-ligated stomachs were filled with mannitol, GFSM mixture and honey (1800 mOsmol/kg water) to test the effect of the hyperosmolar solutions on gastric fluid content and acid secretion. The rate of gastric emptying of the three test solutions (1800 mOsmol/kg) was measured by the phenol red method. RESULTS: Intragastric administration of mannitol, GFSM mixture or honey prevented the formation of mucosal lesions in an osmolality-dependent manner. Using the pylorus-ligated stomach model, the test solutions led to a net increase of luminal fluid volume without affecting acid content. Hyperosmolar solutions presented a delayed gastric emptying if compared to a nonnutrient solution made of carboxymethyl cellulose. CONCLUSIONS: The observed results suggest that hyperosmolar solutions can prevent the formation of hemorrhagic lesions by luminal dilution of the necrotising agent and acid, an effect which may be potentiated by a lowered gastric emptying rate.

The effect of osmolality changes on gastric mucosal endogenous prostacyclin levels in drug-induced experimental ulcer model of rat.

Osmolality changes evoked with intragastric administration of natural honey or mannitol, significantly decreased the gastric ulceration of rats induced by indomethacin. Together with this effect, a parallel increase was detectable in the mucosal level of endogenous prostacyclin. Although many processes may be involved in this phenomenon, the authors explain their data with a stimulating effect on gastric mucosal microcirculation due to osmolality changes.

Effects of sodium fluoride on water and acid secretion, soluble mucus and adherent mucus of the rat stomach.

Chronic and acute ingestion of fluoride may lead to both structural and functional alterations of the gastric mucosa. The aim of this study was to investigate the effects of sodium fluoride on gastric secretion and mucosal barrier. Filling the rat stomach for 1 h with sodium fluoride (5 and 20 mmol/L) induced an increase in fluid, fucose and galactose output. This effect was accompanied by a marked pH-dependent reduction of titratable acidity of the lumen. The amount of Alcian blue bound to adherent mucus was reduced in a pH-independent manner by sodium fluoride. The absence of a correlation between soluble glycoproteins and adherent mucus suggests that sodium fluoride does not stimulate mucus secretion, but rather acts as a barrier-breaking agent by its accumulation, together with acid, into the mucosa.

Effects of aqueous extracts from Quercus ilex L. root bark, Punica granatum L. fruit peel and Artemisia herba-alba Asso leaves on ethanol-induced gastric damage in rats.

The gastroprotective effect of tannic acid and the aqueous extract of Quercus ilex L. root bark, Punica granatum L. fruit peel and Artemisia herba-alba Asso leaves was investigated in the rat against ethanol-induced damage. Tannic acid, Q. ilex and P. granatum extracts gave 100% precipitation of ovine haemoglobin in vitro, whereas A. herba-alba extract was devoid of any protein-binding property. Oral administration of these plant extracts or tannic acid induced a significant decrease in gastric lesions (47.7%-76%). The observed protection was more pronounced when the test solution was given at the same time with ethanol, except for Q. ilex extract. The acid content of the stomach was significantly increased by P. granatum (368%) and A. herba-alba (251%) extracts prepared in ethanol. It is suggested that monomeric and polymeric polyphenols can strengthen the gastric mucosal barrier.

Prevention of ethanol-induced gastric lesions in rats by natural honey and glucose-fructose-sucrose-maltose mixture.

The cytoprotective properties of various natural honey specimens and of a glucose-fructose-sucrose-maltose mixture (GFSM) against gastric ethanol-induced lesions have been evaluated in rats. GFSM mixture and honey (2.5 g kg-1) were given orally 30 min before administration of 100% ethanol (5 ml kg-1) for a further 15-min period. Animal pretreatment with GFSM or honey prevented the formation of gastric lesions. The number and severity of haemorrhagic lesions were reduced by 98%. Stomach acid content increased by 110-703% according to honey specimens. The similar protective effects of honey and GFSM mixture suggest that carbohydrates at high concentrations behave as mild irritants that can induce adaptive cytoprotection.