Effect of pyridoxine and magnesium on stress-induced gastric ulcers in mice selected for low or high blood magnesium levels.

Gastric ulcers were induced by immobilization in adult female mice with genetically low (MGL) or high (MGH) blood magnesium levels, obtained by selective breeding at the CSAL-CNRS (Orléans, France). All animals, fed with the same standard diet rich in magnesium, were divided into four groups of 20 animals and injected subcutaneously every 2 days for 10 days with isotonic saline (group 1), pyridoxine chlorhydrate 1.11 mg/kg in saline (group 2), magnesium lactate 149 mg/kg in saline (group 3) or both pyridoxine and magnesium (group 4). Subsequently, animals were submitted to a complete fast and an immobilization stress for 17 h. Then, they were sacrificed and the gastric mucosa was dissected for ulcer count. Among the controls (group 1), the mean number of gastric ulcers per mouse was significantly larger in the MGL than in the MGH line (p = 0.0003). In the MGH line, no significant differences were observed between control and treated groups. In the MGL line, pyridoxine associated or not with magnesium (groups 2 and 4) significantly reduced the mean number of ulcers. Magnesium treatment alone (group 3) had little effect. These results can be compared with the greater vulnerability to stress previously observed in Swiss mice fed with a magnesium-deficient diet. However, in this latter group, the number of stress ulcers was reduced not only by pyridoxine but also by the sole magnesium treatment, contrary to our present findings in MGL mice.