In vitro and non-invasive invivo effects of the cannabinoid-1 receptor agonist AM841 on gastrointestinal motor function in the rat

BackgroundCannabinoids have been traditionally used for the treatment of gastrointestinal (GI) symptoms, but the associated central effects, through cannabinoid-1 receptors (CB1R), constitute an important drawback. Our aims were to characterize the effects of the recently developed highly potent long-acting megagonist AM841 on GI motor function and to determine its central effects in rats. MethodsMale Wistar rats were used for invitro and invivo studies. The effect of AM841 was tested on electrically induced twitch contractions of GI preparations (invitro) and on GI motility measured radiographically after contrast administration (invivo). Central effects of AM841 were evaluated using the cannabinoid tetrad. The non-selective cannabinoid agonist WIN 55,212-2 (WIN) was used for comparison. The CB1R (AM251) and CB2R (AM630) antagonists were used to characterize cannabinoid receptor-mediated effects of AM841. Key ResultsAM841 dose-dependently reduced invitro contractile activity of rat GI preparations via CB1R, but not CB2R or opioid receptors. In vivo, AM841 acutely and potently reduced gastric emptying and intestinal transit in a dose-dependent and AM251-sensitive manner. The invivo GI effects of AM841 at 0.1mg/kg were comparable to those induced by WIN at 5mg/kg. However, at this dose, AM841 did not induce any sign of the cannabinoid tetrad, whereas WIN induced significant central effects. Conclusions & InferencesThe CB1R megagonist AM841 may potently depress GI motor function in the absence of central effects. This effect may be mediated peripherally and may be useful in the treatment of GI motility disorders.