Possible dissociation of central dopamine receptor antagonism and cataleptic behavior.

A new chemical, 2-[4-[4-(7,9-dioxo-6-thia-8-azaspiro[4,4] nonan-8-yl)-butyl]-1-piperazinyl]pyridine-3-carbonitrile hydrochloride (MJ-13980-1), referred to in this report as MJ-13980, displaced in vitro [3H]spiperone binding, elevated serum prolactin concentrations, and decreased apomorphine-induced stereotyped behavior in male rats. These indicated that MJ-13980 acts as a dopamine (DA) receptor antagonist. However, MJ-13980 (10 mg/kg) elicited only a very small amount of cataleptic behavior and antagonized that produced by haloperidol (HAL), a classical DA receptor blocker and potent inducer of cataleptic behavior. At a lower dose, MJ-13980 (1.0 mg/kg) produced no cataleptic behavior but against decreased that produced by HAL. These results suggest that the antagonistic interaction of MJ-13980 at central DA receptors is not associated with the production of cataleptic behavior.