Background. It has been proven that damage to the gastricmucosa is the result of the combined effects of acidopeptic agents including infection with Helicobacter pylori and insufficient protective mechanisms of the mucosa. Thickness of gastric mucus is very important protective factor. We can hypothetically expect that fasting may cause changes in the thickness of gastric mucus layer, which may in certain circumstances contribute to the conditions for mucosal injury. We have therefore conducted an experimental study on laboratory rats, aiming to assess the changes in the thickness of gastric mucus after 8 and 24-hour periods of fasting. Methods and Results. We measured gastric mucus thickness with the aid of microelectrodes in 279 laboratory rats (group I) after 8 hours of fasting (2 measurements each, total of 558 measurements), followed by the same measurement in 70 laboratory rats (group II) after a 24-hour fasting. Group I had a gastric mucus thickness of 595±10 (mean ± SD, µm); in group II the thickness was 502±10 (mean ± SD, µm). After statistical analysis of the homogeneity of the two populations (Fisher’s analysis), it has been proven that both groups belong to the same basic population sample. The statistical evaluation of the thickness of gastric mucus in both groups showed thinning of the mucus layer to 1 % of the significant statistical difference. The difference between both groups is statistically significant. Conclusions. The thickness of gastric mucus is reduced after 24 hours’ fasting in laboratory rats. This change is statistically significant (P<0,01). It can be hypothesized that – under the specific conditions – this process can facilitate the injury of gastric mucosa.

        Key words: protective mechanisms of gastric mucosa, thickness of gastric mucus, fasting.