Hydrocortisone has a biphasic effect on rat gastric mucosal prostaglandin generation in vivo: inhibition at low doses, stimulation at high doses.

To determine the effect of different doses of hydrocortisone sodium succinate (HC) on rat gastric mucosal prostaglandin synthesis, two experiments were performed. In the first experiment, 20 male Lewis rats were divided into 4 groups of 5 rats each and gavaged either with 2 ml of water (control) or different concentrations of HC (10 mg/ml, 100 mg/ml and 500 mg/ml). In the second experiment in a similar design, lower doses of HC were used (water, 0.1 mg/ml, 0.50 mg/ml and 5.0 mg/ml). The rats were killed after 1 h and three 3 x 3 mm pieces of gastric tissue were removed from each rat and incubated for the determination of prostaglandin E2 and 6-keto-prostaglandin F1 alpha accumulation in the medium measured by radioimmunoassay. At low doses HC inhibits rat gastric mucosal prostaglandin synthesis whereas at higher doses HC stimulates it. This biphasic effect of HC on gastric mucosal prostaglandin synthesis may help explain its role in ulcerogenesis.