Characteristics of 3H-cis-flupenthixol binding to calf brain membranes

The binding of 3H-cis flupenthixol (3H-FPT) to calf brain membranes was investigated in vitro. Highest levels of 3H-FPT binding were observed in striatum and nucleus accumbens, whilst no significant binding was observed in pituitary. The potencies of neuroleptics, dopaminergic ergot alkaloids and dopamine (DA) agonists in inhibiting 3H-FPT binding to calf striatal membranes were compared with their potencies in inhibiting 3H-spiperone (3H-SPIP) binding and DA-stimulated adenylate cyclase (AC). A high correlation was observed between drug potencies in inhibiting 3H-FPT binding and DA stimulated AC. However, potencies of the drugs inhibiting 3H-SPIP binding were only weakly correlated with their potencies in inhibiting either 3H-FPT binding or DA stimulated AC. A detailed analysis of the inhibition of 3H-FPT binding by butyrophenones revealed two classes of 3H-FPT binding sites. It is suggested that 3H-FPT binds predominantly to a class of dopaminergic sites associated with DA-stimulated AC.