Intragastric infusion of the bitter tastant quinine suppresses hormone release and antral motility during the fasting state in healthy female volunteers.

Background: Intragastric administration of the bitter tastant denatonium benzoate inhibits the increase of motilin plasma levels and antral contractility. While these findings suggest that gastrointestinal bitter taste receptors could be new targets to modulate gastrointestinal motility and hormone release, they need confirmation with other bitter receptor agonists. The primary aim was to evaluate the effect of intragastric administration of the bitter tastant quinine-hydrochloride (QHCl) on motilin and ghrelin plasma levels. Secondly, we studied the effect on interdigestive motility.

Methods: Ten healthy female volunteers were recruited (33±4 y; 22±0.5 kg/m²). Placebo or QHCl (10 μmol/kg) was administered intragastrically through a nasogastric feeding tube after an overnight fast in a single-blind randomized fashion. Administration started 20 min after the first phase III of the migrating motor complex. The measurement continued for another 2 h after the administration. Blood samples were collected every 10 min with the baseline sample taken 10 min prior to administration.

Key Results: The increase in plasma levels of motilin (administration; P=.04) and total ghrelin (administration; P=.02) was significantly lower after QHCl. The fluctuation of octanoylated ghrelin was reduced after QHCl (time by administration; P=.03). Duodenal motility did not differ. The fluctuation of antral activity differed over time between placebo and QHCl (time by administration; P=.03).

Conclusions And Inferences: QHCl suppresses the increase of both motilin and ghrelin plasma levels. Moreover, QHCl reduced the fluctuation of antral motility. These findings confirm the potential of bitter taste receptors as targets for modifying interdigestive motility in man.