PERIPHERAL CORTICOTROPIN-RELEASING HORMONE MAY PROTECT THE GASTRIC MUCOSA AGAINST INDOMETHACIN-INDUCED INJURY THROUGH INVOLVEMENT OF GLUCOCORTICOIDS

The hypothalamic-pituitary-adrenocortical (HPA) system is a key hormonal branch of the brain-gut axis in stress and corticotropin-releasing hormone (CRH) is a principal stimulator of the HPA system. According to our finding activation of the HPA system has gastroprotective role in stress and CRH may protect the gastric mucosa against stress-induced injury through involvement of glucocorticoids. To extend this idea to indomethacin-induced gastric injury in the present work we studied whether CRH may protect the gastric mucosa against ulcerogenic action of indomethacin (IM) through involvement of glucocorticoids. CRH administration (1.25 mu g/kg and 2.5 mu g/kg, i.p.) markedly, dose-dependently, increased plasma corticosterone level and significantly, dose-dependently, suppressed the occurrence of gastric erosion induced by IM (35 mg/kg, s.c.) in conscious rats. To estimate the role of glucocorticoids in CRH-induced gastroprotection, the effect of CRH (1.25 mu g/kg) on the IM-induced gastric erosion was studied after acute reduction of corticosterone release by metyrapone (30 mg/kg, i.p., 30 min before CRH administration) or by CRH receptor type 1 antagonist NBI 27914 (10 mg/kg, i.p., 15 min before CRH administration) and also after occupation of glucocorticoid receptors by their antagonist RU-38486 (20 mg/kg, i.p., 2 h before CRH administration). The effects were compared with those in control rats without acute reduction of corticosterone release or occupation of glucocorticoid receptors. Both metyrapone and NBI 27914 injected shortly before CRH administration caused an inhibition of CRH-induced corticosterone response and prevented protective effect of CRH on the gastric mucosa against the IM-induced erosion. The gastroprotective effect of CRH was also eliminated by the pretreatment with glucocorticoid receptor antagonist RU-38486. The results obtained suggest that exogenous CRH may protect the gastric mucosa against IM-induced gastric injury through involvement of glucocorticoids.