Dose-dependent effects of linear and cyclic somatostatin on ethanol-induced gastric erosions: the role of mast cells and increased vascular permeability in the rat.

Somatostatin prevents hemorrhagic gastric erosions produced by ethanol. In this paper we describe studies with linear (reduced) and cyclic (oxidized) synthetic somatostatin-14 in the rat model of ethanol-induced gastric mucosal injury. The linear form of somatostatin was more potent at concentrations of 10(-9) to 10(-8) mol per rat than the cyclic isomere. However, at a concentration of 10(-7) mol per rat i.p. injection of linear somatostatin significantly (P less than 0.01) enhanced gastric erosions caused by the alcohol. The area of hemorrhagic mucosal lesions correlated significantly (r = -0.846) with mast cell depletion in the gastric mucosa of the animals. Increased vascular permeability and mast cell degranulation were also observed after intradermal injection of linear or cyclic somatostatin. The 'cytoprotective' as well as the aggravating potency of linear somatostatin may be connected to gastric mucosal mast cell activity in the rat.