Journal of Neuroscience, Vol 8, 3360-3375, Copyright © 1988 by Society for Neuroscience
Expression of calcium/calmodulin-dependent protein kinase in relation to dopamine islands and synaptic maturation in the cat striatum
H Newman-Gage and AM Graybiel
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge 02139.
During pre- and postnatal development the dopamine-containing nigrostriatal
afferents of the striatum are arranged as a conspicuous series of patches
(the "dopamine islands"). The development of this dopamine island system,
which metamorphoses in early postnatal life to the striosomal architecture
of the adult, has recently received considerable attention, but the factors
initiating and influencing maturation of this architecture are largely
unknown. In an attempt to clarify the relationships between the onset of
clustering of dopamine- containing afferents, the grouping of neurons
within future striosomes and the maturation of synapses in the striatum, we
compared the initial prenatal appearance and subsequent development of
immunohistochemical markers for the dopamine-containing innervation
[tyrosine hydroxylase (TH)-like immunoreactivity], for synaptic vesicles
(SV48-like immunoreactivity), and for a phosphorylation-related enzyme
Ca2+/calmodulin-dependent protein kinase type II (CaM kinase II-like
immunoreactivity) that is expressed in virtually all striatal neurons by
adulthood. Here we present evidence that during striatal ontogeny, both
neurons and neuropil expressing CaM kinase II-like immunoreactivity and
SV48-positive terminals form discrete patches that are in register with
dopamine islands. It is CaM kinase II-positive elements, however, rather
than the TH-positive island fibers (or SV48- positive synapses), that
initially form overt clusters. Dopamine- containing fibers begin to
innervate the striatal anlage just prior to embryonic day (E) 32. Their
distribution follows the general lateral to medial developmental gradient
characteristic of the striatum but is not yet distinctly islandic. At this
time, CaM kinase II-like immunoreactivity was very weak or not present at
all and SV48-like immunoreactivity was undetectable. By E36, CaM kinase
II-positive neurons are visible in discrete patches of immunopositive
neuropil, but only faint inhomogeneities are detectable in the distribution
of TH- positive fibers and scarcely any SV48-like immunoreactivity can be
seen. By E45, all 3 markers are focused in typical islandic patterns, and
they remain so into the early postnatal period. These observations suggest
a developmental sequence in which dopamine-containing fibers invade the
striatal anlage prior to forming distinct islandic foci and prior to the
maturational events signaled by the production of CaM kinase II within the
neurons and neuropil of future striosomes.(ABSTRACT TRUNCATED AT 400 WORDS)