AUTORADIOGRAPHIC LOCALIZATION OF EXTRASTRIATAL D-2-DOPAMINE RECEPTORSIN THE HUMAN BRAIN USING [I-125] EPIDEPRIDE

Epidepride is a benzamide with high affinity for central D-2- and D-3- dopamine receptors. The anatomical distribution of [I-125]epidepride binding was examined by autoradiography, using postmortem human whole- hemisphere cryosections. The density of [I-125]epidepride binding site s was high in caudate nucleus and putamen. [I-125]epidepride also labe led receptors in extrastriatal region such as in the pallidum, some th alamic nuclei, the neocortex, and the substantia nigra. The neocortica l binding was heterogeneously distributed. In most cortical regions, b inding sites were located in superficial layers (I-II). However, in ba sal levels of the occipital cortex, [I-125]epidepride binding was loca ted in a deeper layer, probably corresponding to layer V. Competition studies indicated that most of the [I-125]epidepride binding represent ed predominantly D-2-dopamine receptors, in striatal as well as in ext rastriatal regions. The presence of extrastriatal D-2-dopamine recepto r populations is of particular interest for research on schizophrenia and antipsychotic drug action. (C) 1996 Wiley-Liss, Inc.