J Neurogastroenterol Motil.  2015 Jul;21(3):404-413. 10.5056/jnm14143.

Effects of Intraduodenal Infusions of L-phenylalanine and L-glutamine on Antropyloroduodenal Motility and Plasma Cholecystokinin in Healthy Men

• Steinert R
• Landrock M
• Horowitz M
• Feinle-Bisset C

• KMID: 2433480
• DOI: http://doi.org/10.5056/jnm14143

Abstract

BACKGROUND/AIMS
Dietary proteins have potent eating-inhibitory and glucose-lowering effects, which may be mediated via effects of amino acids on gastrointestinal hormone and motor function, although little information is available. We have now evaluated the effects of L-phenylalanine (L-Phe) and L-glutamine (L-Gln) on antropyloroduodenal motility and plasma cholecystokinin (CCK) concentrations.
METHODS
Two double-blind, 3-way cross-over studies were performed, each including 10 healthy, normal-weight men. We determined the antropyloroduodenal motor and plasma CCK responses to 90-minute intraduodenal infusions of L-Phe (study A) or L-Gln (study B), each at 0.15 kcal/min (total 13.5 kcal), or 0.45 kcal/min (total 40.5 kcal), or saline (control), in randomized fashion.
RESULTS
Intraduodenal L-Phe at 0.45 kcal/min, but not at 0.15 kcal/min, suppressed antral (P < 0.01), and stimulated phasic (P < 0.01), but not tonic, pyloric, or duodenal pressures, while L-Phe at both 0.15 kcal/min and 0.45 kcal/min stimulated plasma CCK. In contrast, L-Gln had no effect on antral, duodenal or pyloric pressures, or plasma CCK.
CONCLUSIONS
Intraduodenal infusions of L-Phe and L-Gln, in doses of 0.15 kcal/min and 0.45 kcal/min for 90 minutes, have different effects on antropyloroduodenal motility and CCK in normal-weight men. The modulation of antral and pyloric pressures and CCK may contribute to the eating-inhibitory effects of oral L-Phe, possibly through the slowing of gastric emptying.

Keyword

Amino acids; Eating; Gastrointestinal hormones; Gastrointestinal motility; Humans

MeSH Terms

Amino Acids
Cholecystokinin*
Cross-Over Studies
Dietary Proteins
Eating
Gastric Emptying
Gastrointestinal Hormones
Gastrointestinal Motility
Glutamine*
Humans
Male
Phenylalanine*
Plasma*
Amino Acids
Cholecystokinin
Dietary Proteins
Gastrointestinal Hormones
Glutamine
Phenylalanine