SR 141716A, a cannabinoid receptor antagonist, reverses the behavioural effects of anandamide-treated rats

We employed the CBI cannabinoid receptor antagonist SR 141716A (3 mg/kg, i. p.) to investigate whether behavioural effects induced in rats by anandamid e, an endogenous cannabinoid (20 mg/kg, i.p,), were mediated by the cannabi noid CBL receptor. Anandamide reduced ambulatory (67%) and non-ambulatory a ctivities (rearing and grooming, 84% and 90% respectively), with a strong c ataleptic effect, produced hypothermia (about -1 degrees C) and hindlimb sp laying, and reduced defecation (79%). It did not significantly increase eit her the tail-flick or hot-plate latencies. Except for the decreased defecat ion, these responses were all blocked by SR 141716A. Although only single d oses of the agonist and antagonist were used, the findings indicate that th ese behavioural effects are probably mediated by an interaction with cannab inoid CBI receptors. (C) 1999 Lippincott Williams & Wilkins.