From gastroprotective to proulcerogenic action of glucocorticoids on the gastric mucosa.

Glucocorticoids may have dual action on the gastric mucosa: physiological gastroprotective and pathological proulcerogenic one. In the present study we investigated how gastroprotective action of glucocorticoids can be transformed to proulcerogenic effect. Dose- and time-dependent effects of single injection of dexamethasone on cold-restraint-induced gastric erosions, corticosterone and blood glucose levels, somatic parameters were investigated in fasted rats. Dexamethasone at a dose of 1 mg/kg decreased the gastric erosion area and maintained blood glucose level in fasted rats in the case of its injection 1 h before the stress. A dose of 1 mg/kg has been selected for the time-dependent study. The results demonstrate that single injection of dexamethasone at a dose of 1 mg/kg may attenuate or aggravate cold-restraint-induced gastric erosions depending on the time of the injection before the stress. Gastroprotective action of dexamethasone was observed in the case of its injection 1 and 12 h before cold-restraint. The further increase in the time interval caused transformation of gastroprotective action of dexamethasone to proulcerogenic effect. Both short-term and long-term dexamethasone action resulted in maintenance of blood glucose level in fasted rats. The results suggest that glucocorticoid-induced long-lasting maintenance of blood glucose levels accompanied with the signs of their catabolic effect and dexamethasone-induced corticosterone deficiency may be responsible, at least partly, for the transformation of gastroprotective action of glucocorticoids to their proulcerogenic effect.