Stress ulcer accompanying subarachnoid hemorrhage--a new rat model.

New rat model of stress ulcer, related to subarachnoid hemorrhage (SAH) was devised. A 0.2 ml of the arterial blood, obtained from another rat of the same litter, was injected into the cisterna magna and 4 days later, mild stress, consisting of restraint plus water-immersion for 3 hours to the injected rat, produced gastric ulcers. These lesions were far more marked than in usual rats undergoing the same stress (P less than 0.001). Using this "SAH-stress model", effects of various counteracting measures were examined. Based on the results, we concluded that SAH produced a hypersensitivity or an abnormal excitability of the autonomic nervous centers, and the relatively mild stress effectively weakened the gastric defensive factors and strengthened the gastric aggressive factors, thus resulting in ulcer formation.