The Bitter Taste Receptor Agonist Quinine Reduces Calorie Intake and Increases the Postprandial Release of Cholecystokinin in Healthy Subjects.
OBJECTIVE
Bitter taste receptors are expressed throughout the digestive tract. Data on animals have suggested these receptors are involved in the gut hormone release, but no data are available in humans. Our aim is to assess whether bitter agonists influence food intake and gut hormone release in healthy subjects.


METHODS
Twenty healthy volunteers were enrolled in a double-blind cross-over study. On 2 different days, each subject randomly received an acid-resistant capsule containing either placebo or 18 mg of hydrochloride (HCl) quinine. After 60 minutes, all subjects were allowed to eat an ad libitum meal until satiated. Plasma samples were obtained during the experiment in order to evaluate cholecystokinin (CCK) and ghrelin levels. Each subject was screened to determine phenylthiocarbamide (PTC) tasting status.


RESULTS
Calorie intake was significantly lower when subjects received HCl quinine than placebo (514 ± 248 vs 596 ± 286 kcal; P = 0.007). Significantly higher CCK ΔT90 vs T0 and ΔT90 vs T60 were found when subjects received HCl quinine than placebo (0.70 ± 0.69 vs 0.10 ± 0.86 ng/mL, P = 0.026; 0.92 ± 0.75 vs 0.50 ± 0.55 ng/mL, P = 0.033, respectively). PTC tasters ingested a significantly lower amount of calories when they received HCl quinine compared to placebo (526 ± 275 vs 659 ± 320 kcal; P = 0.005), whereas no significant differences were found for PTC non-tasters (499 ± 227 vs 519 ± 231 kcal; P = 0.525).


CONCLUSIONS
This study showed that intra-duodenal release of a bitter compound is able to significantly affect calorie intake and CCK release after a standardized meal. Our results suggest that bitter taste receptor signaling may have a crucial role in the control of food intake.
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Paolo
http://orcid.org/0000-0002-4604-0126
P
Andreozzi
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Giovanni
http://orcid.org/0000-0002-1467-1134
G
Sarnelli
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Marcella
http://orcid.org/0000-0001-5996-4259
M
Pesce
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Francesco P
http://orcid.org/0000-0002-1084-3373
FP
Zito
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Alessandra D
AD
Alessandro
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Viviana
http://orcid.org/0000-0001-9569-2369
V
Verlezza
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Ilaria
http://orcid.org/0000-0003-0387-1461
I
Palumbo
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Fabio
http://orcid.org/0000-0001-9149-3872
F
Turco
Department of Clinical and Experimental Medicine, Second University of Naples, Italy.
Katherine
http://orcid.org/0000-0002-3652-5154
K
Esposito
Department of Clinical Medicine and Surgery, "Federico II" University, Naples, Italy.
Rosario
http://orcid.org/0000-0003-0768-8381
R
Cuomo
Cholecystokinin; Food intake; Ghrelin; Quinine; Taste