Journal of Neuroscience, Vol 9, 865-875, Copyright © 1989 by Society for Neuroscience
ARPP-21, a cyclic AMP-regulated phosphoprotein enriched in dopamine- innervated brain regions. II. Immunocytochemical localization in rat brain
CC Ouimet, HC Hemmings Jr and P Greengard
Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York 10021.
ARPP-21, a cAMP-regulated phosphoprotein, has been studied by
immunocytochemistry to determine its cellular and regional distribution in
rat brain. This study demonstrates that ARPP-21 immunoreactivity is present
throughout the cytoplasm of immunoreactive neurons and that most of the
immunoreactivity is associated with the basal ganglia. Within the
caudatoputamen (CP), nucleus accumbens, olfactory tubercle, bed nucleus of
the stria terminalis, and portions of the amygdaloid complex, ARPP-21 is
present in neuronal somata and dendrites. In brain regions known to receive
projections from these nuclei, immunoreactivity is present in puncta
(presumed axons and axon terminals). These regions include the globus
pallidus, ventral pallidum, entopeduncular nucleus, lateral preoptic area,
and substantia nigra. Within the basal ganglia, ARPP-21 immunoreactivity is
most intense in the olfactory tubercle, nucleus accumbens, medial portion
of the CP, and the ventral retrochiasmatic pocket of the CP. These same
areas comprise the limbic striatum, and ARPP-21 is the first substance
found to be specifically enriched therein. The possibility is discussed
that ARPP-21 mediates effects of multiple first messengers, including
dopamine and vasoactive intestinal polypeptide, that act through cAMP.