Specific binding of [11C]spiroperidol in rat brain in vivo.

Spiroperidol labeled with carbon-11, a short-lived positron-emitting radionuclide, was used to determine the time course of specific binding of this radioligand to the neuroleptic receptor in vivo in the rat. The three major bran pools--specifically bound, nonspecifically bound, and free (unbound)--were determined over a 60-mm time course by a rapid filtration technique, utilizing (-)- and (+)-butaclamol pretreatments to assess total and nonspecifically bound activities, respectively, in striatum and cerebellum. The ratio of specifically to nonspecifically bound pools in the striatum was 4.1 at 30 min and 5.1 at 60 min. Thus [11C]spiroperidol may be useful for labeling neuroleptic receptors in vivo for serial studies using positron emission transaxial tomography.