Human chorionic gonadotropin regulates gastric emptying in ovariectomized rats

Prolongation of gastrointestinal transit resulting in nausea and vomiting in pregnancy (NVP) is the most common phenomenon during the first trimester of pregnancy. Increased human chorionic gonadotropin (hCG) concentration during the first trimester is the most likely cause of NVP. The aim of this study was to investigate the effect of hCG on gastrointestinal transit and plasma concentrations of cholecystokinin (CCK) in ovariectomized (Ovx) rats. I.p. injection of hCG was used to evaluate the dose effect of hCG on gastrointestinal transit in Ovx rats. The CCK antagonist lorglumide was used to clarify the role of CCK in regulating gastrointestinal transit. Gastrointestinal transit was assessed 15 min after intragastric gavage of a mixture of 10% charcoal and Na(2)(51)CrO(4) (0.5 μCi/ml). After i.p. administration of hCG, gastric emptying was inhibited in Ovx rats, but intestinal transit was not affected. Plasma CCK concentrations were increased in a dose-dependent manner after hCG treatment, and gastric emptying showed a significant negative correlation with CCK concentrations (P=0.01, r(2)=-0.5104). Peripheral administration (i.p.) of lorglumide, a selective CCK(1) receptor antagonist, attenuated the hCG-induced inhibition of gastric emptying in Ovx rats, whereas central administration via the i.c.v. route did not. hCG treatment of Ovx rats inhibits gastric emptying in a dose-dependent manner via a peripheral mechanism of CCK hypersecretion and activation of CCK(1) receptors.