Stress-induced corticosterone rise maintain gastric mucosal integrity in rats

To investigate contribution of glucocorticoids to the maintenance of gastric mucosal integrity during stress we predominantly used ulcerogenic stress models. Using these models we demonstrated that glucocorticoids released in response to the ulcerogenic stimuli attenuated their harmful action on the gastric mucosa. In the present study we hypothesized that mild stressors does not damage the gastric mucosa due to gastroprotective action of glucocorticoids released in response to these stressors.

To verify the hypothesis the effects of normally non-ulcerogenic mild stimuli (15-30 min cold-restraint) on the gastric mucosal integrity have been studied under the circumstances of inhibition of the hypothalamic-pituitaryadrenocortical axis in rats. The hypothalamic-pituitary-adrenocortical axis was inhibited by: 1) fast inhibitory action of metyrapone, inhibitor glucocorticoid synthesis; 2) fast inhibitory action of NBI 27914, the selective antagonist of cortricotropin- releasing factor receptor type 1; 3) delayed inhibitory action of a single pharmacological dose of cortisol injected one week before the onset of stress stimulus.

Each of these pretreatments significantly decreased 15-30 min cold-restraint-produced corticosterone levels: 37.2±1 vs 22.5±1.2 (p<0.05) after metyrapone; 52.1±0.9 vs 41.4±1 (p<0.05) after NBI, and 64.2±4.2 vs 16.7±1.5 (p<0.05) after cortisol pretreatment. The inhibition of stress-induced corticosterone rise resulted in an ap - pearance of gastric lesions after the onset of these mild stressors in rats.

The results suggest that in rats with inhibited stress-induced corticosterone rise normally non-ulcerogenic stimuli are transformed into ulcerogenic ones and confirm the hypothesis. The findings further support for the point of view that glucocorticoids released during acute stress are gastroprotective factors.