Effect of long term estrogen and lithium treatment on restraint induced gastric erosion in intact and ovariectomized rats.

Gastric erosions were induced in intact and ovariectomized rats by subjecting them to 24 h restraint. In association with erosion, histidine decarboxylase was determined in the glandular portion of the stomach. Under these experimental conditions, 8 weeks ovariectomy significantly reduced the severity of restraint induced gastric erosions. Administration of estradiol benzoate 10 micrograms/d for 4 weeks before restraint did not influence the severity of the erosions in either the control or ovariectomized rats. Lithium chloride 2mEq/kg given daily for 7 weeks to intact and ovariectomized animals did not modify the gastric erosion severity. However, combined treatment with estrogen and lithium, significantly decreased the severity of gastric erosions in intact but not in ovariectomized rats and this was associated with a significant increase in the endogenous histamine content of the gastric mucosa. The data show that ovariectomy protected rats against gastric erosions and that estrogen replacement treatment did not reduce the protection afforded by ovariectomy. They also demonstrate that estrogen-lithium administration reduces erosions and that the mechanism could be through decreasing histamine release from gastric tissue.