NEUROMEDIATORS IN AGING AND GASTRIC-MUCOSAL INJURY

The hypothesis that the improvement of neurochemical changes involving the brain dopaminergic and cholinergic systems in aged rats may be re lated to the their capacity of coping with stress has been investigate d by testing the effect of various dopaminergic and cholinergic drugs on stress-induced gastric ulcer development. The model of cold-plus-re straint stress induced gastric lesions has been used in Sprague-Dawley rats aged 24 months. compared to young animals aged 2 months. An incr eased incidence of gastric ulcers was found in old animals. When these animals were treated with cholinergic or dopaminergic drugs. they sho wed a higher resistance to stress-induced biological modifications. Th e most potent drugs were found to be the cholinergic drug. physostigmi ne and the dopaminergic drug. deprenyl. Furthermore. the induction of hyperprolactinemia by pituitary homografts under the kidney capsule wa s also accompanied by a reduced incidence of cold-plus-restraint stres s induced gastric lesions in aged rats. These results may suggest that the influence of neurotransmitter or hormonal factors on the brain ma y affect the response of aged rats to the application of physical stre ss.