Effect of N-methyl-N'-nitro-N-nitrosoguanidine on carbohydrate profiles of non-metaplastic rat gastric mucosa.

The effect of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on the mucin phenotype of non-metaplastic gastric mucosa in the rat was studied histochemically. Animals were exposed to MNNG in drinking water (83 mg/l) for 12 weeks. Carcinogen treatment was then discontinued and the animals (27 in the treatment group and 25 in the control group) were examined after another 44 weeks. Glycosylation was analysed with histochemical stains for sialomucins and sulphomucins and with peroxidase-conjugated lectins (GS-II, SBA, DBA, UEA-I, and WGA). Sialo- and sulphomucins remained quantitatively unchanged, only a slight increase of acid mucins in the antral glands was observed. The analysis of the lectin binding patterns, however, revealed a significant increase for WGA-binding glycoproteins in the surface mucous cells and gastric pits, while DBA binding was significantly decreased (P < 0.05). GS-II lectin bound specifically to the proliferative compartment in the gastric fundus, consisting of mucous neck cells, and was significantly increased after MNNG treatment. No specific alterations were detected in lectin binding to parietal or chief cells. It is concluded, therefore, that treatment of gastric mucosa with MNNG alters the glycoprotein metabolism before intestinal metaplasia can be observed.