AGGRESSIVE ROLE OF VASOPRESSIN IN DEVELOPMENT OF DIFFERENT GASTRIC-LESIONS IN RATS

The effects of endogenous or exogenous vasopressin in models of gastri c mucosal injury with a different pathophysiology (ethanol, indomethac in, reserpine, cold-restraint stress and haemorrhagic shock-induced le sions) were investigated in rats. [Mca(1),TyrMe(2),Arg(8)]vasopressin, a vasopressin presser (V-1) receptor antagonist, was found to reduce dose dependently the extent of the lesions in all models, and to prote ct the deeper layer of the mucosa (assessed by histology). Endogenous vasopressin deficiency, as in Brattleboro homozygous rats, had a simil ar effect. [Lys(8)]Vasopressin injected exogenously aggravated all typ es of lesions in normal rats. Circulating vasopressin levels were incr eased by ethanol, reserpine, cold-restraint stress and haemorrhagic sh ock, but not by indomethacin, whereas the intramucosal vasopressin con tent was found to be elevated in all models. Additionally, specific bi nding sites for vasopressin were shown on the blood vessels of the gas tric mucosa (assessed by autoradiography). It is concluded that vasopr essin plays a significant aggressive role in the generation of these t ypes of lesions.