An endogenous cannabinoid tone attenuates cholera toxin-induced fluid accumulation in mice.
OBJECTIVE
Cholera toxin (CT) is the most recognizable enterotoxin causing secretory diarrhea, a major cause of infant morbidity and mortality throughout the world. In this study, we investigated the role of the endogenous cannabinoid system (i.e., the cannabinoid receptors and their endogenous ligands) in CT-induced fluid accumulation in the mouse small intestine.


METHODS
Fluid accumulation was evaluated by enteropooling; endocannabinoid levels were measured by isotope-dilution gas chromatography mass spectrometry; CB(1) receptors were localized by immunohistochemistry and their messenger RNA (mRNA) levels were quantified by reverse-transcription polymerase chain reaction (PCR).


RESULTS
Oral administration of CT to mice resulted in an increase in fluid accumulation in the small intestine and in increased levels of the endogenous cannabinoid, anandamide, and increased expression of the cannabinoid CB(1) receptor mRNA. The cannabinoid receptor agonist CP55,940 and the selective cannabinoid CB(1) receptor agonist arachidonoyl-chloro-ethanolamide inhibited CT-induced fluid accumulation, and this effect was counteracted by the CB(1) receptor antagonist SR141716A, but not by the CB(2) receptor antagonist SR144528. SR141716A, per se, but not the vanilloid VR1 receptor antagonist capsazepine, enhanced fluid accumulation induced by CT, whereas the selective inhibitor of anandamide cellular uptake, VDM11, prevented CT-induced fluid accumulation.


CONCLUSIONS
These results indicate that CT, along with enhanced intestinal secretion, causes overstimulation of endocannabinoid signaling with an antisecretory role in the small intestine.
Izzo
Angelo A
AA
Department of Experimental Pharmacology, University of Naples, "Frederico II", Naples, Italy. aaizzo@unina.it
Capasso
Francesco
F
Costagliola
Anna
A
Bisogno
Tiziana
T
Marsicano
Giovanni
G
Ligresti
Alessia
A
Matias
Isabel
I
Capasso
Raffaele
R
Pinto
Luisa
L
Borrelli
Francesca
F
Cecio
Aldo
A
Lutz
Beat
B
Mascolo
Nicola
N
Di Marzo
Vincenzo
V
D000577:Amides; D000581:Amidohydrolases / Q000032:analysis; D000818:Animals; D063385:Cannabinoid Receptor Modulators; D002714:Chlorisondamine / Q000494:pharmacology; D002772:Cholera Toxin / Q000633:toxicity*; D063388:Endocannabinoids; D004983:Ethanolamines; D005231:Fatty Acids, Unsaturated / Q000032:analysis / Q000502:physiology*; D007150:Immunohistochemistry; D007421:Intestine, Small / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010169:Palmitic Acids / Q000032:analysis; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000099252:Fatty Acid Amide Hydrolases
D000577:Amides; D000581:Amidohydrolases; D063385:Cannabinoid Receptor Modulators; D002714:Chlorisondamine; D002772:Cholera Toxin; D063388:Endocannabinoids; D004983:Ethanolamines; D005231:Fatty Acids, Unsaturated; D010169:Palmitic Acids; D043882:Receptors, Cannabinoid; D011955:Receptors, Drug; D000099252:Fatty Acid Amide Hydrolases; C005958:palmidrol