Influence of feeding situation on stomach ulcers and organ weights in rats in the activity-stress ulcer paradigm.

Rats housed in running wheel activity cages except for 1 hr each day, during which time they were fed in their home cages, revealed more stomach ulceration, a higher level of brain MHPG-SO4, and larger weight changes in the thymus, spleen and adrenal gland, compared to rats housed in running-wheel activity cages and fed 1 hr daily in those same cages. Rats in the latter group showed more stress pathology than did control rats which were housed in standard home cages but which received the same restricted (1 hr per day) feeding schedule. These results did not support the idea that excessive running might occur in response to certain motivational states (e.g., frustration due to restricted feeding). The data suggested that feeding activity-stress rats in their home cages might aggravate the development of stomach ulcers coincident with the organ weight changes and the enhancement of noradrenaline turnover in the brain.