Gastric emptying in OLETF rats not expressing CCK-A receptor gene.

We have very recently demonstrated the low acidity of gastric juice and the high susceptibility to the development of gastric ulceration in Otsuka Long-Evans Tokushima Fatty (OLETF) rats not expressing CCK-A receptors. In the present study, gastric emptying in this strain was examined and compared with control Long-Evans Tokushima Otsuka (LETO) rats. Gastric emptying was evaluated by the phenol red method. Gastric emptying 30 and 60 min after a liquid meal in OLETF rats was significantly delayed compared to that in control LETO rats. Intraperitoneal injection of CCK-8 at a dose of 5 microg/kg significantly inhibited gastric emptying in control LETO rats, whereas the same dose of CCK-8 failed to inhibit gastric emptying in OLETF rats. These results suggest for the first time that gastric emptying was suppressed in OLETF rats. We also confirmed with this mutant that CCK delays gastric emptying through the CCK-A receptors.