SYNTHESIS AND BINDING-PROPERTIES OF [H-3]NNC-12-0781, A NEW RADIOLIGAND FOR THE DOPAMINE REUPTAKE SYSTEM

The tritiated dopamine reuptake inhibitor [H-3]NNC 12-0781 luorophenyl )-methoxy)-ethyl]-4-(3-(2-furanyl)-2,3- [H-3]-propyl)-piperazine) was radiolabelled in one step starting from y)-ethyl]-4-(3-(2-furanyl)-2-p ropenyl)-piperazine, using tritium gas and PdO as catalyst. The radioc hemical purity of [3H]NNC 12-0781 was higher than 99% after HPLC purif ication with a specific radioactivity of 21 Ci/mmol. [H-3]NNC 12-0781 bound specifically to rat striatum in vitro at +4 degrees C with a K-d of 1.76 nM and B(max)of 587 fmol/mg tissue. The nonspecific binding w as about 10% at K-d. At +37 degrees C no acceptable binding was observ ed. The association of [3H]NNC 12-0781 thus has the characteristics of a radioligand for the dopamine transporter in vitro at +4 degrees C.