Abstract
Rats which were housed in the activity-wheel cages and fed for 1hr daily, exerted high running activity and body weight loss. The rats which run more significantly during the 1hr feeding period die and reveal stomach lesions. Therefore, the ulcer was designated as "Activity-stress ulcer". They also revealed atrophy of the thymus and spleen, and hypertrophy of the adrenals. These phenomena resemble with "General adaptation syndrome of Selye". When rats were exposed to activity-stress, the plasma corticosterone increased and the antibody titer decreased in accordance with the length of activity-stress period. The appearance of dead rat was in accordance with decrease of antibody titer. When the ulcer development was prevented by psychotropic drugs, the corticosterone level was lower. These results suggest that the pathophy-siological changes of rats exposed to activity-stress relates with augmentation of plasma corticosterone closely. And, the role of the pituitary-adrenal hormones in stress-induced immunological changes was discussed.
