Julie Gardener
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The role of cannabinoid receptors in intestinal motility, defaecation and diarrhoea in rats
Angelo A. Izzo, a, Nicola Mascolob, Luisa Pinto, a, Raffaele Capassob and Francesco Capasso, , a
a Department of Experimental Pharmacology, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy
b Department of Pharmaceutical Sciences, Via Ponte Don Melillo, 84084, Fisciano, Salerno, Italy
Received 29 March 1999; revised 10 September 1999; accepted 16 September 1999. Available online 20 December 1999.
Abstract
We have studied the effects of the cannabinoid receptor agonists (R)-(+)[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone (WIN 55,212-2, 0.3—5 mg/kg, i.p.) and (−)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol) (CP 55,940, 0.03—1 mg/kg, i.p.), the cannabinoid CB1 receptor antagonist (N-piperidin-1-yl)-5-(4-chlorophenyl)-1-2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716A, 0.3—5 mg/kg, i.p.) and the cannabinoid CB2 receptor antagonist N-[-(1S)-endo-1,3,3-trimethyl bicyclo [2.2.1] heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528, 1 mg/kg, i.p.) on intestinal motility, defaecation and castor-oil (1 ml/100 g rat, orally)-induced diarrhoea in the rat. SR141716A, but not SR144528, increased defaecation and upper gastrointestinal transit, while WIN 55,212-2 and CP 55,940 decreased upper gastrointestinal transit but not defaecation. WIN 55,212-3 (5 mg/kg), the less active enantiomer of WIN 55,212-2, was without effect. A per se non-effective dose of SR141716A (0.3 mg/kg), but not of SR144528 (1 mg/kg) or the opioid receptor antagonist, naloxone (2 mg/kg i.p.), counteracted the inhibitory effect of both WIN 55,212-2 (1 mg/kg) and CP 55,940 (0.1 mg/kg) on gastrointestinal motility. WIN 55,212-2 did not modify castor-oil-induced diarrhoea, while CP 55,940 produced a transient delay in castor-oil-induced diarrhoea at the highest dose tested (1 mg/kg), an effect counteracted by SR141715A (5 mg/kg). These results suggest that (i) intestinal motility and defaecation could be tonically inhibited by the endogenous cannabinoid system, (ii) exogenous activation of cannabinoid CB1 receptors produces a reduction in intestinal motility in the upper gastrointestinal tract but not in defaecation, (iii) endogenous or exogenous activation of cannabinoid CB2 receptors does not affect defaecation or intestinal motility and (iv) the cannabinoid receptor agonist, CP 55,940, possesses a weak and transient antidiarrhoeal effect while the cannabinoid receptor agonist, WIN 55,212-2, does not possess antidiarrhoeal activity.
Source: ScienceDirect - European Journal of Pharmacology : The role of cannabinoid receptors in intestinal motility, defaecation and diarrhoea in rats
Angelo A. Izzo, a, Nicola Mascolob, Luisa Pinto, a, Raffaele Capassob and Francesco Capasso, , a
a Department of Experimental Pharmacology, University of Naples "Federico II", Via D. Montesano 49, 80131 Naples, Italy
b Department of Pharmaceutical Sciences, Via Ponte Don Melillo, 84084, Fisciano, Salerno, Italy
Received 29 March 1999; revised 10 September 1999; accepted 16 September 1999. Available online 20 December 1999.
Abstract
We have studied the effects of the cannabinoid receptor agonists (R)-(+)[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de]-1,4-benzoxazin-6-yl]-1-naphthalenylmethanone (WIN 55,212-2, 0.3—5 mg/kg, i.p.) and (−)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol) (CP 55,940, 0.03—1 mg/kg, i.p.), the cannabinoid CB1 receptor antagonist (N-piperidin-1-yl)-5-(4-chlorophenyl)-1-2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716A, 0.3—5 mg/kg, i.p.) and the cannabinoid CB2 receptor antagonist N-[-(1S)-endo-1,3,3-trimethyl bicyclo [2.2.1] heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide (SR144528, 1 mg/kg, i.p.) on intestinal motility, defaecation and castor-oil (1 ml/100 g rat, orally)-induced diarrhoea in the rat. SR141716A, but not SR144528, increased defaecation and upper gastrointestinal transit, while WIN 55,212-2 and CP 55,940 decreased upper gastrointestinal transit but not defaecation. WIN 55,212-3 (5 mg/kg), the less active enantiomer of WIN 55,212-2, was without effect. A per se non-effective dose of SR141716A (0.3 mg/kg), but not of SR144528 (1 mg/kg) or the opioid receptor antagonist, naloxone (2 mg/kg i.p.), counteracted the inhibitory effect of both WIN 55,212-2 (1 mg/kg) and CP 55,940 (0.1 mg/kg) on gastrointestinal motility. WIN 55,212-2 did not modify castor-oil-induced diarrhoea, while CP 55,940 produced a transient delay in castor-oil-induced diarrhoea at the highest dose tested (1 mg/kg), an effect counteracted by SR141715A (5 mg/kg). These results suggest that (i) intestinal motility and defaecation could be tonically inhibited by the endogenous cannabinoid system, (ii) exogenous activation of cannabinoid CB1 receptors produces a reduction in intestinal motility in the upper gastrointestinal tract but not in defaecation, (iii) endogenous or exogenous activation of cannabinoid CB2 receptors does not affect defaecation or intestinal motility and (iv) the cannabinoid receptor agonist, CP 55,940, possesses a weak and transient antidiarrhoeal effect while the cannabinoid receptor agonist, WIN 55,212-2, does not possess antidiarrhoeal activity.
Source: ScienceDirect - European Journal of Pharmacology : The role of cannabinoid receptors in intestinal motility, defaecation and diarrhoea in rats
