Anti-inflammatory effects of angiotensin II [AT.sub.1] receptor antagonism prevent stress-induced gastric injury

Stress reduces gastric blood flow and produces acute gastric mucosal lesions. We studied the role of angiotensin II in gastric blood flow and gastric ulceration during stress. Spontaneously hypertensive rats were pretreated for 14 days with the [AT.sub.1] receptor antagonist candesartan before cold-restraint stress. [AT.sub.1] receptors were localized in the endothelium of arteries in the gastric mucosa and in all gastric layers. [AT.sub.1] blockade increased gastric blood flow by 40-50%, prevented gastric ulcer formation by 70-80% after cold-restraint stress, reduced the increase in adrenomedullary epinephrine and tyrosine hydroxylase mRNA without preventing the stress-induced increase in adrenal corticosterone, decreased the stress-induced expression of TNF-[alpha] and that of the adhesion protein ICAM-1 in arterial endothelium, decreased the neutrophil infiltration in the gastric mucosa, and decreased the gastric content of [PGE.sub.2]. [AT.sub.1] receptor blockers prevent stress-induced ulcerations by a combination of gastric blood flow protection, decreased sympathoadrenal activation, and anti-inflammatory effects (with reduction in TNF-[alpha] and ICAM-1 expression leading to reduced neutrophil infiltration) while maintaining the protective glucocorticoid effects and [PGE.sub.2] release. Angiotensin II has a crucial role, through stimulation of [AT.sub.1] receptors, in the production and progression of stress-induced gastric injury, and [AT.sub.1] receptor antagonists could be of therapeutic benefit. gastric blood flow; prostaglandins; tumor necrosis factor