The role of endocannabinoids in the regulation of gastric emptying: alterations in mice fed a high-fat diet.
OBJECTIVE
Endocannabinoids (via cannabinoid CB(1) receptor activation) are physiological regulators of intestinal motility and food intake. However, their role in the regulation of gastric emptying is largely unexplored. The purpose of the present study was to investigate the involvement of the endocannabinoid system in the regulation of gastric emptying in mice fed either a standard diet (STD) or a high-fat diet (HFD) for 14 weeks.


METHODS
Gastric emptying was evaluated by measuring the amount of phenol red recovered in the stomach after oral challenge; CB(1) expression was analysed by quantitative reverse transcription-PCR; endocannabinoid (anandamide and 2-arachidonoyl glycerol) levels were measured by liquid chromatography-mass spectrometry.


RESULTS
Gastric emptying was reduced by anandamide, an effect counteracted by the CB(1) receptor antagonist rimonabant, but not by the CB(2) receptor antagonist SR144528 or by the transient receptor potential vanilloid type 1 (TRPV1) antagonist 5'-iodoresiniferatoxin. The fatty acid amide hydrolase (FAAH) inhibitor N-arachidonoyl-5-hydroxytryptamine (but not the anandamide uptake inhibitor OMDM-2) reduced gastric emptying in a way partly reduced by rimonabant. Compared to STD mice, HFD mice exhibited significantly higher body weight and fasting glucose levels, delayed gastric emptying and lower anandamide and CB(1) mRNA levels. N-arachidonoylserotonin (but not rimonabant) affected gastric emptying more efficaciously in HFD than STD mice.


CONCLUSIONS
Gastric emptying is physiologically regulated by the endocannabinoid system, which is downregulated following a HFD leading to overweight.
Di Marzo
V
V
Endocannabinoid Research Group, Institute of Biomolecular Chemistry, National Research Council, Pozzuoli, Naples, Italy.
Capasso
R
R
Matias
I
I
Aviello
G
G
Petrosino
S
S
Borrelli
F
F
Romano
B
B
Orlando
P
P
Capasso
F
F
Izzo
A A
AA
D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology; D001786:Blood Glucose; D001835:Body Weight; D063385:Cannabinoid Receptor Modulators / Q000502:physiology*; D002853:Chromatography, Liquid; D004041:Dietary Fats / Q000494:pharmacology*; D015536:Down-Regulation; D063388:Endocannabinoids; D005746:Gastric Emptying / Q000502:physiology*; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008813:Mice, Inbred ICR; D010637:Phenolsulfonphthalein; D053284:Polyunsaturated Alkamides / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D043884:Receptor, Cannabinoid, CB1 / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D001095:Arachidonic Acids; D001786:Blood Glucose; D063385:Cannabinoid Receptor Modulators; D004041:Dietary Fats; D063388:Endocannabinoids; D053284:Polyunsaturated Alkamides; D012333:RNA, Messenger; D043884:Receptor, Cannabinoid, CB1; D010637:Phenolsulfonphthalein; C078814:anandamide