Some novel 5-hydroxytryptamine1A (5-HT1A) receptor agonists reduce gastric acid and pepsin secretion, reduce experimental gastric mucosal injury and enhance gastric mucus in rats.

The present studies examined the actions of a series of novel arylpiperazine 5-hydroxytryptamine1A (5-HT1A) agonists, developed originally for anxiolytic efficacy, in several models of gastric secretion and experimental gastric mucosal injury. These models included conscious gastric acid secretion, pylorus ligation (gastric acid and pepsin secretion), stress-induced gastric mucosal injury, ethanol-induced gastric mucosal damage and gastric adherent mucus levels. 2-(4-[4-(4-Nitropyrazol-1- yl)butyl]-1-piperazinyl)pyrimidine (E4414) and 2-(4-[4-(4-chloropyrazol-1-yl)butyl]-1-piperazinyl)pyrimidine dihydrochloride (E4424) significantly inhibited gastric acid secretion in conscious as well as in pylorus-ligated rats. Both compounds also significantly reduced pepsin secretion in pylorus-ligated animals. E4414 and E4424 significantly reduced both stress-induced and ethanol-induced gastric mucosal injury, and both compounds significantly maintained gastric adherent mucus levels in rats subjected to stress. The antisecretory and gastroprotective actions of E4414 and E4424 were of significantly greater magnitude than those of the reference 5-HT1A agonists, buspirone and 8-hydroxy-2-(di-n- propylamino)tetralin. These results suggest that some novel 5-HT1A agonists exert gastroprotection not only through reduction of aggressive elements in the gut (acid and pepsin secretion) but also through enhancement of defensive gastrointestinal factors such as adherent mucus.