To investigate the role of oxygen radicals in the pathogenesis of gastric mucosal lesions induced by psychological stress, we exposed 3-mo-old C3H mice to feeding-restriction stress for 1 to 5 days.

Serial changes in the activities of antioxidant enzymes in the gastric mucosa, together with O2- production by macrophages, were measured.

The stress increased the plasma cortisol level and started to produce acute gastric lesions (AGL) on the 2nd day.

Before the development of AGL, the activity of superoxide dismutase in the gastric mucosa had already decreased and the ability of O2- production by macrophages was enhanced from the 1st day.

This suggests that oxygen radicals play some role in the development of AGL induced by the stress.