CERULETIDE SUPPRESSES ROTATIONAL BEHAVIOR IN LESIONED RATS VIA CCKA RECEPTORS

The effects and pharmacological mechanisms underlying the inhibiting e ffect of ceruletide, a cholecystokinin (CCK)-related peptide, on apomo rphine-induced turning behavior in 6-hydroxydopamine lesioned rats wer e investigated. For this purpose, selective CCK(A) and CCK(B) receptor antagonists were used. Ceruletide (50-400 mug/kg, s.c.) dose dependen tly suppressed apomorphine-induced rotational behavior. The antiapomor phine effect of ceruletide was reversed by the selective CCK(A) recept or antagonist, devazepide, but not by the selective CCK(B) receptor an tagonist, L-365,260. This suggests that the suppression ceruletide exe rts on hyperactive nigrostriatal dopamine neurons is mediated by CCK(A ) receptors.