Ai. Levey et al., LOCALIZATION OF D(1) AND D(2) DOPAMINE-RECEPTORS IN BRAIN WITH SUBTYPE-SPECIFIC ANTIBODIES, Proceedings of the National Academy of Sciences of the United Statesof America, 90(19), 1993, pp. 8861-8865
Five or more dopamine receptor genes are expressed in brain. However,
the pharmacological similarities of the encoded D1-D5 receptors have h
indered studies of the localization and functions of the subtypes. To
better understand the roles of the individual receptors, antibodies we
re raised against recombinant D1 and D2 proteins and were shown to bin
d to the receptor subtypes specifically in Western blot and immunoprec
ipitation studies. Each antibody reacted selectively with the respecti
ve receptor protein expressed both in cells transfected with the cDNAs
and in brain. By immunocytochemistry, D1 and D2 had similar regional
distributions in rat, monkey, and human brain, with the most intense s
taining in striatum, olfactory bulb, and substantia nigra. Within each
region, however, the precise distributions of each subtype were disti
nct and often complementary. D1 and D2 were differentially enriched in
striatal patch and matrix compartments, in selective layers of the ol
factory bulb, and in either substantia nigra pan compacta or reticulat
a. Electron microscopy demonstrated that D1 and D2 also had highly sel
ective subcellular distributions. In the rat neostriatum, the majority
of D1 and D2 immunoreactivity was localized in postsynaptic sites in
subsets of spiny dendrites and spine heads in rat neostriatum. Presyna
ptic D1 and D2 receptors were also observed, indicating both subtypes
may regulate neurotransmitter release. D1 was also Present in axon ter
minals in the substantia nigra. These results provide a morphological
substrate for understanding the pre- and postsynaptic functions of the
genetically defined D1 and D2 receptors in discrete neuronal circuits
in mammalian brain.