Background: Endocannabinoid N-arachidonoylethanolamine (AEA, anandamide) is a double- edged sword: it inhibits intestinal motility and visceral pain through its neuroinhibitory effects, but may also have proalgesic or proinflammatory effects by activating transient receptor potential vanilloid-1 (TRPV1). AEA levels may be increased by inhibition of fatty acid amide hydrolase (FAAH). We hypothesize that N-arachidonoyl-serotonin (AA-5-HT), as a dual FAAH inhibitor and TRPV1 antagonist, enhances the beneficial effects of AEA by: (1) increasing its endogenous levels and (2) blocking TRPV1. Dual FAAH and TRPV1 blockade may be a potential treatment for GI hypermotility and visceral hyperalgesia. Methods: Male CD1 mice were used in this study. Whole-mount preparations of the colonic myenteric plexus were immunostained for cannabinoid-1 (CB1) receptor, TRPV1 and FAAH. The effects of AA-5-HT on the following parameters were studied: (1) colonic contractility induced by electrical field stimulation (EFS; 4 Hz); in vitro, (2) excitatory junction potential (EJP) and fast (f) and slow (s) inhibitory junction potential (IJP); in vitro, (3) colonic expulsion of a bead; in vivo, (4) visceral hyperalgesia to distensive stimuli and visceromotor response (VMR) induced by intra-colonic administration of the protease-activated receptor-2 activating peptide SLIGRL (20μg/mouse); in vivo and (5) colonic levels of AEA, 2-AG, palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), measured by mass spectrometry. Results: CB1-immunoreactive enteric neurons exhibited TRPV1 immunoreactivity. Only some TRPV1-positive neurons also expressed CB1 receptors, which were not co-localized with FAAH. AA-5-HT (100nM- 10μM) decreased EFS induced colonic longitudinal muscle contractility by ~60% at the highest concentration. These effects were abolished by the TRPV1 antagonist, 5` -IRTX (75nM), but not by the CB1 antagonist, SR141716 (100nM). Electrical stimulation of the enteric neurons induced EJP followed by fIJP and sIJP. AA-5-HT inhibited EJP at 1μM by ~30% and fIJP and sIJP at 10μM by ~50%. Both SR141716 (1μM) and 5` - IRTX (1μM) reversed the effects of AA-5-HT on the junction potentials. AA-5-HT (20mg/ kg i.p.) inhibited colonic propulsion by ~30 %. This effect was blocked by SR141716 (1mg/ kg), but not by 5` -IRTX (0.75mg/kg). AA-5-HT (20mg/kg) decreased VMR by ~50-60% at distention levels of 30-60mmHg. This effect was not sensitive to SR141716 or5` -IRTX. AA- 5-HT (20mg/kg) significantly increased colonic AEA, but not 2-AG, PEA or OEA levels. Conclusion: Dual inhibition of FAAH and TRPV1 channels has neuromodulatory effects in the mouse intestine. The effects of AA-5-HT on visceral sensation and intestinal motility parameters are differentially mediated by CB1, TRPV1 and non-CB1/TRPV1-mediated mechanisms.
Regulation of the Enteric Neuromotor and Sensory Functions in the Mouse With N-Arachidonoyl-Serotonin (AA-5-HT), a Dual Fatty Acid Amide Hydrolase (FAAH) Inhibitor and TRPV1 Antagonist / Mohammad, Bashashati; Jakub, Fichna; Fabiana, Piscitelli; Capasso, Raffaele; Izzo, ANGELO ANTONIO; Andrei, Sibaev; Jean Pierre, Timmermans; Nicolas, Cenac; Nathalie, Vergnolle; Vincenzo, Di Marzo; Martin, Storr. - In: GASTROENTEROLOGY. - ISSN 0016-5085. - 150:4(2016), pp. 48-48. [10.1016/S0016-5085(16)30285-2]
Regulation of the Enteric Neuromotor and Sensory Functions in the Mouse With N-Arachidonoyl-Serotonin (AA-5-HT), a Dual Fatty Acid Amide Hydrolase (FAAH) Inhibitor and TRPV1 Antagonist
CAPASSO, RAFFAELE;IZZO, ANGELO ANTONIO;
2016
Abstract
Background: Endocannabinoid N-arachidonoylethanolamine (AEA, anandamide) is a double- edged sword: it inhibits intestinal motility and visceral pain through its neuroinhibitory effects, but may also have proalgesic or proinflammatory effects by activating transient receptor potential vanilloid-1 (TRPV1). AEA levels may be increased by inhibition of fatty acid amide hydrolase (FAAH). We hypothesize that N-arachidonoyl-serotonin (AA-5-HT), as a dual FAAH inhibitor and TRPV1 antagonist, enhances the beneficial effects of AEA by: (1) increasing its endogenous levels and (2) blocking TRPV1. Dual FAAH and TRPV1 blockade may be a potential treatment for GI hypermotility and visceral hyperalgesia. Methods: Male CD1 mice were used in this study. Whole-mount preparations of the colonic myenteric plexus were immunostained for cannabinoid-1 (CB1) receptor, TRPV1 and FAAH. The effects of AA-5-HT on the following parameters were studied: (1) colonic contractility induced by electrical field stimulation (EFS; 4 Hz); in vitro, (2) excitatory junction potential (EJP) and fast (f) and slow (s) inhibitory junction potential (IJP); in vitro, (3) colonic expulsion of a bead; in vivo, (4) visceral hyperalgesia to distensive stimuli and visceromotor response (VMR) induced by intra-colonic administration of the protease-activated receptor-2 activating peptide SLIGRL (20μg/mouse); in vivo and (5) colonic levels of AEA, 2-AG, palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), measured by mass spectrometry. Results: CB1-immunoreactive enteric neurons exhibited TRPV1 immunoreactivity. Only some TRPV1-positive neurons also expressed CB1 receptors, which were not co-localized with FAAH. AA-5-HT (100nM- 10μM) decreased EFS induced colonic longitudinal muscle contractility by ~60% at the highest concentration. These effects were abolished by the TRPV1 antagonist, 5` -IRTX (75nM), but not by the CB1 antagonist, SR141716 (100nM). Electrical stimulation of the enteric neurons induced EJP followed by fIJP and sIJP. AA-5-HT inhibited EJP at 1μM by ~30% and fIJP and sIJP at 10μM by ~50%. Both SR141716 (1μM) and 5` - IRTX (1μM) reversed the effects of AA-5-HT on the junction potentials. AA-5-HT (20mg/ kg i.p.) inhibited colonic propulsion by ~30 %. This effect was blocked by SR141716 (1mg/ kg), but not by 5` -IRTX (0.75mg/kg). AA-5-HT (20mg/kg) decreased VMR by ~50-60% at distention levels of 30-60mmHg. This effect was not sensitive to SR141716 or5` -IRTX. AA- 5-HT (20mg/kg) significantly increased colonic AEA, but not 2-AG, PEA or OEA levels. Conclusion: Dual inhibition of FAAH and TRPV1 channels has neuromodulatory effects in the mouse intestine. The effects of AA-5-HT on visceral sensation and intestinal motility parameters are differentially mediated by CB1, TRPV1 and non-CB1/TRPV1-mediated mechanisms.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
