Journal of Neuroscience, Vol 11, 810-821, Copyright © 1991 by Society for Neuroscience
Development of striatal compartmentalization following pre- or postnatal dopamine depletion
AM Snyder-Keller
Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany 12201-0509.
Nigrostriatal dopamine (DA) projections terminate in distinct patches
during the late prenatal and early postnatal period in the rat. During the
first postnatal week, patches of DA fibers overlap with clusters of
striatal neurons that share several identified characteristics. The early
segregation of striatal cell types into either these patches or the
surrounding matrix becomes a permanent organizational feature of the
striatum. In order to determine whether the heterogeneous distribution of
DA influences the formation of cellular patches, the developmental
organization of chemically identifiable cell types was examined in normal
rats and in rats DA depleted as infants (0 or 3 d) or in utero (embryonic
days 17-18). During the first postnatal week, corresponding patches of DA
afferents and substance P (SP)- immunoreactive neurons existed in the
striatum of normal animals, and AChE-positive zones overlapped these
patches in the lateral striatum. Injection of 6-hydroxydopamine into the
lateral ventricles of fetal or infant rats produced a dramatic loss of
striatal DA terminals. Neither the patchy distribution of SP-immunoreactive
neurons nor the distinctive pattern of AChE staining present during the
first 2 postnatal weeks was disrupted. During the third postnatal week,
cells immunoreactive for leu-enkephalin or calbindin-D28k were confined to
the matrix compartment, and this compartmentalization was also not
noticeably changed by pre- or postnatal DA depletion. In adult animals,
overlapping patches of leu-enkephalin- and SP-immunoreactive fibers were
observed, regardless of whether any DA terminals remained. Thus, the basic
organization of the striatal patch and matrix compartments develops
normally in the absence of DA innervation through much of the formative
period. Although these observations do not completely dismiss the
possibility that the first DA afferents to appear in the striatal primordia
influence contracted striatal cells to develop the patch phenotype, they
suggest that the patchy distribution of DA afferents may be secondary to
the early clustering of striatal neurons forming the patch compartment.