Central, but not peripheral administration of substance P induces opioid-mediated gastroprotection in the rat

Introduction: Although the gastrointestinal effects of the tachykinin substance P (SP) have been studied for a long period, its role in the regulation of gastric mucosal integrity has not been fully clarified. Both aggravation of ethanol-induced damage and lack of effect have been reported after peripheral injection of SP in rats (Evangelista et al., 1987; 1991; Karmeli et al., 1991). In contrast, centrally injected SP reduced cold-restraint stress-induced gastric ulcers (Hernandez et al., 1983). The aim of our study was 1) to analyze the effect of SP in an acid-independent ulcer model in rats, and 2) to clarify…