The effects of 5-hydroxytryptamine1a receptor agonist, buspirone on the gastric fundus accommodation in an animal model using guinea pigs

Background: To date, few animal experiments have been conducted to examine the effects and mechanisms of buspirone in inducing the relaxation of the gastric fundus. The aim of this study is to examine the effects and mechanisms of buspirone, 5-HT_1a receptor agonist, in the accommodation of gastric fundus muscle in an animal experimental model using guinea pigs. Methods: In the current study, we performed an immunohistochemistry for 5-HT_1a receptors in the tissue samples collected from the stomach of guinea pig, an ex vivo experiment to examine the electrical field stimulation (EFS)-induced relaxation of the circular muscle in the gastric fundus in guinea pigs and an in vivo experiment to measure the intragastric pressure through the insertion of the balloon catheter in the fundus. Key Results: Immunohistochemical stains for 5-HT_1a receptor could confirm the expression of 5-HT_1a receptor in guinea pig stomach. There was a significant dose-dependent inhibition of the EFS-induced relaxation of fundic muscle strips following the treatment with WAY-100635 (5-HT_1a antagonist), but this was significantly improved following the treatment with buspirone. An in vivo measurement of the gastric fundic tone showed that there was a significant decrease in the intragastric pressure at same volume by pretreatment with buspirone as compared with the vehicle control, but this could be prevented with the treatment with WAY-100635. Conclusions & Inferences: Based on our results, it can be concluded that buspirone is effective in relaxing the gastric fundus via 5-HT_1a receptor pathway in both in vitro and in vivo experimental models using guinea pigs. Buspirone has relaxatory effects on gastric fundus of Guinea pig via 5-HT_1a pathway.