INTRASTRIATAL INJECTION OF CANNABINOID RECEPTOR AGONISTS INDUCED TURNING BEHAVIOR IN MICE

When injected unilaterally into the mouse striatum, cannabinoid agonis ts such as Win 55212-2 (1-100 ng/mouse), CP 55940 (0.1-50 ng/mouse), a nd anandamide (0.5-50 ng/mouse), the putative endogenous ligand of CB1 receptor, dose-dependently induced turning behavior. SR 141716A dichl orophenyl)-4-methyl-1H-pyrazole-3-carboxamide hydrochloride], the sele ctive antagonist of CB1 receptor, antagonized the three cannabinoid re ceptor agonists-induced turning with similar ED(50)s (0.13-0.15 mg/kg, IP). Spiroperidol (a D-2 receptor blocker), (+)-SCH 23390 (a D-1 rece ptor blocker), or prior 6-OHDA lesions of the striatum blocked Win 552 12-2- and CP 55940-induced turning, thus suggesting the involvement of DA transmission in cannabinoid-induced turning. Taken together, these findings reinforce the notion of a cannabinoid receptor-mediated cont rol of nigrostriatal function.