Species-specific patterns of glycoprotein expression in the developing rodent caudoputamen: Association of 5′-nucleotidase activity with dopamine islands and striosomes in rat,but with extrastriosomal matrix in mouse

The glycoprotein 5′-nucleotidase is a cell surface phosphatase and represents a new marker for striosomes in the adult rat caudoputamen. We report here on its developmental expression in the rat and mouse striatum, and show an unexpected converse 5′-nucleotidase chemoarchitecture of the caudoputamen in these closely related species. In the rat, 5′-nucleotidase activity was first visible as neuropil staining in tyrosine hydroxylase-positive dopamine islands of the midstriatum on postnatal day 1, and by the end of the first postnatal week, 5′-nucleotidase-positive dopamine islands also appeared rostrally. This compartmental pattern persisted thereafter, so that in adult animals, in all but the caudal caudoputamen, zones of enhanced 5′-nucleotidase staining were restricted to calbindin-D_28k-poor striosomes. Weak 5′-nucleotidase activity also emerged in the matrix. In striking contrast, in the mouse striatum, enhanced 5′-nucleotidase activity was preferentially associated with extrastriosomal tissue. Enzymatic reaction first appeared on embryonic day 18, and developed over the first postnatal week into a mosaic pattern in which the matrix was stained but the dopamine islands were unstained. The matrix staining itself was heterogeneous. After the second postnatal week, most of the caudoputamen was stained, and in adult mice only rostral striosomes expressed low 5′-nucleotidase activity. We conclude that in rats, 5′-nucleotidase represents one of the few substances that maintains a preferential dopamine island/striosome distribution during striatal development. In mice, 5′-nucleotidase activity is expressed preferentially in the matrix during development, and its compartmental pattern is gradually lost with maturation, except very rostrally. These findings do not suggest an instructive role of the enzyme in striatal compartment formation in either species, but do suggest the possibility that 5′-nucleotidase contributes to the differentiation of striatal compartments during development. © 1993 Wiley-Liss, Inc.     

Transient compartmental expression of a family of protein tyrosine phosphatases in the developing striatum

The expression of a family of intracellular protein tyrosine phosphatases (STEP) was studied in the striatum of rats during ontogeny. Links between the formation of dopamine islands and STEP immunoreactive patches in the striatum were examined since previous work had suggested that STEP isoforms were selectively expressed in dopaminoceptive brain regions. STEP protein and mRNAs were distributed in a patchy manner during the first postnatal week. By 2 weeks, STEP immunoreactivity was homogeneous, indicating that both patch and matrix neurons express STEP by maturity. Two-color immunofluorescent staining was also performed to compare STEP with specific markers for patch and matrix. Tyrosine hydroxylase immunoreactive fibers from the substantia nigra form distinctive dopamine islands in the striatum during late embryonic development, and occupy the sites of future patches [23,37,38,54]. These fiber islands align with STEP immunoreactive neuronal patches during the first two postnatal weeks, suggesting that STEP is a marker for patch neurons in early postnatal development. When STEP's distribution was compared with other markers for patch (substance P) or matrix (calbindin), STEP co-localized with substance P in most striatal neurons on postnatal days 1 through 7. However, STEP was also expressed within a subset of calbindin-positive neurons in the lateral striatum, but not with these neurons elsewhere in the striatum. By adulthood, STEP colocalized with both markers. These results suggest that STEP is expressed first within patch neurons but not matrix, and subsequently within both. The expression of STEP may be triggered by the arrival of striatal afferents or other regulatory factors.     

Expression of calcium/calmodulin-dependent protein kinase in relation to dopamine islands and synaptic maturation in the cat striatum

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)     

Transient calbindin-D28k-positive systems in the telencephalon: ganglionic eminence, developing striatum and cerebral cortex.

Calbindin-D28k (calbindin) is a member of the superfamily of calcium-binding proteins implicated in the regulation of intracellular calcium. In the mature brain, calbindin is widely expressed in neurons of the forebrain and the hindbrain, and in the telencephalon calbindin-like immunoreactivity is particularly strongly expressed by medium-sized neurons of the striatum and by certain other neurons in the cortex and subcortex. We have traced the development of calbindin expression in the forebrain of the rat, and report here that in addition to the steady development of these calbindin-positive neuronal systems, transient waves of calbindin expression occur in cells of the ventricular zones of the basal ganglia and cortex and in cells of the telencephalic regions derived from these ventricular zones including radial glia of the developing striatum. In the striatum and its ventricular zone (the ganglionic eminence, or GE) we identified four transient calbindin-positive systems in the perinatal period. First, calbindin-immunoreactive cells began to appear in the GE by embryonic day (E)18, and by E20 an extensive dorsal and lateral part of the GE was marked by dense calbindin-like immunoreactivity in the ventricular zone. This calbindin system peaked at postnatal day (P)0-P3 and disappeared by P15. Its presence suggests that the GE is divisible on a molecular basis into lateral and medial districts that may correspond to derivatives of the lateral and medial ventricular ridges. Second, a system of calbindin-positive processes appeared in the dorsal and lateral caudoputamen with temporal and spatial distributions matching the germinal zone system. Many of these processes could be traced from calbindin-positive cells in the ventricular zone of the GE, including processes stretching across the full width of the dorsal caudoputamen. Double-staining experiments demonstrated that these radial processes were Rat.401-positive, suggesting that they form a subset of radial glia in the developing telencephalon. These findings demonstrate that during development calbindin is expressed in glial as well as neural cells. They further suggest that the radial glia associated with the GE form heterogeneous populations, the transient calbindin-positive radial glia being associated with the lateral ridge of the GE and its derivatives. Third, a scattered population of calbindin-positive cells with morphologies different from the common medium-sized calbindin-immunoreactive neurons of the striatum appeared in the dorsal and lateral striatum from about E20 to P15. Some of these cells were close to the transient calbindin-positive radial processes in the same region, but others were not.(ABSTRACT TRUNCATED AT 400 WORDS)     

Patterns of cell and fiber vulnerability in the mesostriatal system of the mutant mouse weaver. I. Gradients and compartments.

In mice carrying the autosomal recessive gene weaver, there is a massive postnatal loss of dopamine in the caudoputamen, the target of the nigrostriatal system, with relative (though not complete) preservation of dopamine in the ventral striatum, a target of the mesolimbic system. There is concomitant death of catecholaminergic neurons in the substantia nigra, with much less cell death in the limbic midbrain area. In the study reported here, we have reexamined the mesostriatal system of weaver mice by means of tyrosine hydroxylase (TH) immunohistochemistry in order to determine the local architecture of the defect within the striatum and substantia nigra. For the dorsal striatum, the most striking finding was the appearance in the weaver caudoputamen of small pockets of especially weak immunostaining within a larger dorsal zone of generally reduced TH-positive neuropil. These pockets were identified as striosomes by calbindin28k and met-enkephalin immunohistochemistry carried out on adjacent sections. In dorsal, central, and caudal sectors of the caudoputamen, there was also more generalized depletion of TH-immunoreactive neuropil. In the mid-brains of the mutants, the patterns of loss of TH-positive neurons appeared to correspond to these distributions of reduced immunostaining in the striatum. In the substantia nigra pars compacta, ventrally situated TH-positive neurons were especially affected, suggesting preferential depletion of TH-positive neurons projecting to striosomes. In addition, there was a central sector of nearly complete loss of TH-positive neurons in the substantia nigra para compacta and a marked depletion of TH-positive neurons in cell group A8 that, together, may have accounted for the diminution of TH-positive innervation of the striatal matrix. We conclude that the effects of the weaver gene discriminate among mesostriatal subsystems not only according to the regional affiliations of these subsystems within the dorsal and ventral striatum, but also according to the preferential association of the subsystems for the striosomal and matrical compartments of the caudoputamen. The depletion of TH-positive innervation was not confined to the dorsal striatum proper. The defect extended into the adjoining nucleus accumbens, where it appeared to affect the lateral "core" division, and included also a lateral part of the olfactory tubercle. Thus, as in the dorsal striatum, the defect in the TH-positive innervation of the ventral striatum closely follows the local architecture of this striatal region. Neuronal loss in the ventral tegmental area was not evident on qualitative analysis, but at the border between lateral cell group A 10 and medial cell group A9 there was obvious loss of immunostained neurons.(ABSTRACT TRUNCATED AT 400 WORDS)     

Increased calbindin-D28k immunoreactivity in striatal projection neurons of R6/2 Huntington's disease transgenic mice

Striatal degeneration in Huntington's disease (HD) is associated with increases in perikaryal calbindin immunolabeling in yet-surviving striatal projection neurons. Since similar increases have also been observed in surviving striatal projection neurons after intrastriatal injection of the excitotoxin quinolinic acid, the increased calbindin in HD striatum has been interpreted to suggest an excitotoxic process in HD. We used immunolabeling to assess if calbindin is elevated in striatal projection neurons of R6/2 HD transgenic mice. These mice bear exon 1 of the human huntingtin gene with 144 CAG repeats and show some of the neuropathological signs (e.g., neuronal intranuclear inclusions) and clinical traits (e.g., wasting prior to early death) of HD. We found an increased frequency of calbindin-immunoreactive neuronal perikarya in the striatum of 6- and 12-week-old R6/2 mice compared to wild-type controls. This increase was most notable in the normally calbindin-poor dorsolateral striatum. We found no significant changes in the total area of striatum occupied by the calbindin-negative striosomes and no consistent changes in striatal calbindin mRNA. The increase in calbindin in R6/2 striatal neurons was thus limited to the matrix compartment, and it may be triggered by increased Ca2+ entry due to the demonstrated heightened NMDA sensitivity of these neurons. The data further support the similarity of R6/2 mice to HD, and are consistent with the occurrence of an excitotoxic process in striatum in both.     

Dynamic regulation of NGFI-A (zif268, egr1) gene expression in the striatum.

The expression of immediate-early genes of the fos/jun leucine zipper family can be regulated in striatal neurons by stimuli affecting the dopaminergic nigrostriatal system. The regulatory effects are gene specific, region specific, and striatal compartment specific. In the experiments reported here, we have explored the possibility that dopaminergic stimulation might also affect striatal expression of NGFI-A, a member of the zinc finger family of immediate-early genes. We treated healthy adult rats with amphetamine or cocaine and monitored the acute response of striatal neurons by in situ hybridization with oligonucleotide probes for NGFI-A mRNA. Both drugs evoked rapid, anatomically patterned increases in NGFI-A mRNA expression in the dorsal striatum (caudoputamen) and in the ventral striatum (nucleus accumbens, olfactory tubercle). The main response to each drug was in medium-sized neurons, known to be the projection neurons of the striatum. At every dose of amphetamine eliciting a response, the increased NGFI-A mRNA expression was preferentially concentrated in striosomes of the rostral caudoputamen, whereas cocaine at each dose given induced expression of NGFI-A mRNA in both striosomes and matrix at these striatal levels. The two indirect agonists evoked NGFI-A expression in both striatal compartments farther caudally, especially in the central and medial caudoputamen. Activation by both drugs was blocked by pretreatment with the D1-selective dopamine receptor antagonist SCH23390. These patterns of NGFI-A activation are remarkably similar to those found for Fos-like immunoreactivity following acute amphetamine and cocaine treatments, suggesting that coordinate activation of members of at least two immediate-early gene families occurs in the striatum following catecholaminergic stimulation. Such patterns of induction strongly support the view that the genomic responsiveness of the striosome and of the matrix compartments of the rostral striatum are distinct at the level of early-response gene expression. These findings raise the interesting possibility that some of the well-known effects of dopaminergic stimulation on neuropeptide and neurotransmitter expression in the striatum may reflect particular combinatorial patterns of immediate-early gene activation.     

Parvalbumin-containing GABAergic interneurons in the rat neostriatum

Antibodies to the intracellular calcium binding protein parvalbumin were shown to label specifically a distinct group of neostriatal GABAergic neurons. These neurons corresponded to the intensely staining subclass of neostriatal GABAergic neurons that have previously been shown to be a class of aspiny interneurons in the neostriatum. The parvalbumin neurons were aspiny neurons with varicose dendrites distributed throughout the neostriatum in a pattern identical to the intensely stained GABA neurons, and both populations of neurons showed increased numbers in the lateral part of the neostriatum. Double labeling of single neurons with both the GABA and parvalbumin antisera showed that all parvalbumin neurons were positive for GABA, but some GABA labelled neurons were not immunoreactive for parvalbumin. These parvalbumin-negative GABAergic neurons were morphologically similar to the spiny projection neurons, which are GABAergic but usually are not so heavily stained. The relationship of the GABA-containing parvalbumin neurons to the striatal mosaic organization was determined by using immunocytochemistry for another calcium binding protein, calbindin D28K, to label the matrix compartment of the striatum. The distribution of parvalbumin-positive neurons relative to the calbindin-positive matrix and calbindin-poor patches was determined by using pairs of adjacent sections stained with the calbindin and parvalbumin antisera. This analysis showed that the somata of the parvalbumin neurons were present in both patch and matrix compartments, and their axons and dendrites crossed the boundaries between compartments. A quantitative analysis of the number of neurons in each compartment revealed that the neurons showed no preferential distribution in either compartment, but instead were present according to the area occupied by that compartment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intrastriatal grafts derived from fetal striatal primordia. I. Phenotypy and modular organization

Fetal striatal grafts display a striking modularity of composition. With acetylcholinesterase (AChE) histochemistry, the tissue of such grafts can be divided into regions with strong AChE staining of the neuropil and regions in which AChE staining of the neuropil is weak. In the experiments reported here, we reexamined the nature of this modularity. Striatal grafts were made by injecting dissociated cells of E15 ganglionic eminence into the striatum of adult rats, which 7 days before had recived intrastriatal deposits of ibotenic acid. Some donors had been exposed to 3H-thymidine at E11-E15. After 9-17 month survivals, the anatomical organization of the grafts was studied by histochemistry, immunohistochemistry, and autoradiography. In every graft, the AChE-rich regions formed patches (P regions) in a larger AChE-poor surround (NP regions). Neurons labeled with 3H-thymidine appeared in both P and NP regions, suggesting that donor cells were distributed in each type of region and that neither type of tissue, P or NP, was composed exclusively of host tissue. In the AChE-rich P regions, markers characteristic of normal perinatal and mature rat striatum were expressed by medium-sized cells: calcium-binding protein (calbindin D28k) immunostaining, metenkephalin (mENK) immunostaining, and, more rarely, somatostatin (SOM) immunostaining. In the NP regions, however, medium-sized cells expressing calbindin and mENK immunostaining were very rare, and there was an abundance of neuronal types not found in normal mature striatal tissue. These included (1) large, multipolar, calbindin-positive neurons with well-ramified, densely stained dendrites, (2) large, SOM-positive neurons with prominent dendritic trees, and (3) mENK-positive cells smaller than typical striatal, medium-sized, mENK-immunoreactive neurons. In Nissl stains, the AChE-rich P regions resembled the normal striatum of mature animals, whereas the AChE-poor NP regions did not. These findings suggest that the P regions of fetal striatal grafts achieve a phenotypy similar to that of normal striatum at maturity and during much of postnatal development. The dominant expression of perikaryal calbindin-like immunoreactivity in the P regions further suggests that these zones have a high proportion of tissue resembling striatal matrix. By contrast, expression of marker antigens in the NP zones of the grafts suggests that these zones are predominantly composed of nonstriatal tissue or that they have the phenotypy of immature striatum intermixed with some nonstriatal cells.(ABSTRACT TRUNCATED AT 400 WORDS)     

Spatial distributions of chemically identified intrinsic neurons in relation to patch and matrix compartments of rat neostriatum

The spatial distributions and dendritic branching patterns of chemically identified subpopulations of striatal intrinsic neurons, defined by immunoreactivity for choline acetyltransferase (ChAT), neuropeptide Y or parvalbumin, were studied in relation to patch and matrix compartments of rat neostriatum. ChAT-immunoreactive cells and fibers showed an uneven pattern of distribution in the striatum. ChAT immunoreactivity was higher in the dorsolateral part and lower in the ventromedial part of the striatum. This regional gradient pattern is the inverse of the overall pattern of calbindin D_28k immunoreactivity. However, in small regions close to the lateral ventricle and globus pallidus, areas containing fewer ChAT-immunoreactive cells and fibers coincided with those containing low calbindin D_28k immunoreactivity. Neuropeptide Y immunoreactivity was uniform in the neostriatum. Certain neuropeptide Y cells (about 20%) were also immunoreactive for calbindin D_28k, indicating that at least a small population of calbindin D_28k-immunoreactive cells are medium aspiny cells. Parvalbumin immunoreactivity was not uniform in the striatum. A higher density of parvalbumin immunoreactivity was found in the neuropil in lateral and caudal parts than in the medial part. Small regions with weaker parvalbumin-immunoreactive neuropil partially corresponded to calbindin D_28k poor patches. Larger cells immunoreactive for parvalbumin were preferentially located in lateral and caudal parts of the striatum. Cells immunoreactive for ChAT, neuropeptide Y or parvalbumin showed basically similar distribution patterns in relation to the patch and matrix compartments. Most stained cells were located in the matrix, but some were located at the borders of patches and a few were inside patches. Most primary dendrites of stained cells in the matrix or patches remained confined to these compartments, but cells on the borders invariably extended dendrites into both compartments. The striatal intrinsic neurons form chemically differentiated neuronal circuits within the matrix, and the patches and those whose dendrites cross the borders may contribute to associational interconnections between the two compartments, unlike the spiny projection neurons whose dendrites are confined to one or the other compartment. © Wiley-Liss, Inc.     

5'-nucleotidase: a new marker for striosomal organization in the rat caudoputamen.

The distribution of the adenosine-producing ectoenzyme 5'-nucleotidase was studied by means of a histochemical lead technique in the caudoputamen of normal adult rats and of rats in which injections either of 6-hydroxydopamine in the medial forebrain bundle or of ibotenic acid in the caudoputamen had been made 1-3 weeks previously. The patterns of striatal 5'-nucleotidase activity in these animals were compared in serial sections to the patterns of calbindin-D28k immunoreactivity and of 3H-naloxone ligand binding, which respectively mark the known matrix and striosome (patch) compartments of the caudoputamen. In the normal rats, 5'-nucleotidase activity was differentially concentrated in striosomes, where it produced a dense staining of the neuropil. The enzymatic staining followed a striosomal distribution in all but the caudal caudoputamen. Within the striatal matrix, 5'-nucleotidase staining also observed a lateromedial density gradient. Depletion of the dopamine-containing nigrostriatal innervation of the caudoputamen with 6-hydroxydopamine did not alter the striosomal selectivity of 5'-nucleotidase activity. Destruction of intrastriatal neurons by ibotenic acid led to a strongly 5'-nucleotidase-positive gliosis within the resulting necrotic region. Elsewhere in the caudoputamen, the enzyme's striosomal distribution was not detectably altered. We conclude that 5'-nucleotidase histochemistry provides an advantageous tool for detecting the striosomal architecture of the rat's caudoputamen. Moreover, 5'-nucleotidase is prominently associated with glial membranes in the central nervous system, so that the concentration of this enzyme in striosomes could mark these as sites of selective glial populations within striatum. These properties and actions of 5'-nucleotidase in purinergic neurotransmission and in neuroadhesion may contribute to the specialized functions of striosomes and matrix.     

Dendritic domains of medium spiny neurons in the primate striatum: Relationships to striosomal borders

Medium spiny neurons are the projection neurons of the striatum. They receive the majority of striatal afferents, and they make up the vast majority of all neurons in the striatum. These densely spiny cells thus constitute a major substrate for input-output processing in the striatum. In the experiments described here we analyzed the dendritic fields of spiny neurons in the squirrel monkey striatum and plotted their orientations with respect to the borders between striosomes and matrix. Medium-sized spiny neurons in the caudate nucleus were filled intracellularly in a fixed-slice preparation with the fluorescent dye Lucifer Yellow. Dendritic arbors were reconstructed following immunostaining of the injected neurons with antiserum to Lucifer Yellow and counterstaining for striosome/matrix compartments. A majority of the medium spiny neurons studied had dendritic arborizations that remained within their compartment of origin. Thus the striosome/matrix subdivision not only partitions neurotransmitter molecules and extrinsic striatal connections into two domains in the primate caudate nucleus, but also constrains the dendritic arbors of many projection neurons there. Other medium spiny neurons, however, in both striosomes and matrix, had dendrites that crossed from one compartment into the other. About a quarter of the spiny neurons reconstructed had at least one such crossing dendrite. These results suggest that compartmentalization of afferent and efferent processing by projection neurons in the primate striatum is not absolute. For a subpopulation of spiny neurons in striosomes and matrix, inputs to one compartment could have a direct influence on output cells of the other. © 1993 Wiley-Liss,Inc.     

Temporal and compartmental restriction of neuron-specific enolase expression in the rat mesostriatal system.

The striatum and the mesencephalic dopamine neurons which innervate it, are each organized into developmentally and biochemically distinct compartments. Striatal patches, characterized in the neonate by high concentrations of opiate receptors and substance P, are innervated prenatally by fibers originating in one group of midbrain dopamine neurons, the ventral tier. By the third postnatal day, a dense dopamine projection from neurons in the dorsal tier of the mesostriatal group innervates non-patch areas of the striatum, i.e. the matrix, and is followed by the appearance there of neurotensin, somatostatin and calcium binding protein. We have recently observed that the period of establishment of connections between dorsal tier dopamine neurons and their target cells in the striatal matrix is accompanied by a surge in expression of the gene coding for tyrosine hydroxylase (TH). In order to determine the overall metabolic state of mesencephalic and striatal neurons during the period of up-regulation of TH gene expression, we have applied immunocytochemistry for neuron specific enolase (NSE), and cytochrome oxidase histochemistry, known markers for neuronal activity, as well as TH immunohistochemistry to the mesencephalon and striatum of postnatally developing rats. At birth, both NSE and cytochrome oxidase were expressed almost exclusively in the patches, appearing in the matrix only after the 2nd postnatal day. Patches of NSE remained visible thru the 14th day. In the mesencephalon, cytochrome oxidase and immunoreactive NSE cells in adjacent sections, were present only in the pars reticulata (i.e. ventral tier). By day 8, both techniques identified nigral cells in the dorsal as well as ventral tiers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative development of D1-dopamine and mu opiate receptors in normal and in 6-hydroxydopamine-lesioned neonatal rat striatum: dopaminergic fibers regulate mu but not D1 receptor distribution.

The postnatal development of D1 dopaminergic receptors (D1 receptors) was investigated in the rat striatum in relation to distribution of mu opiate receptor patches and islandic tyrosine hydroxylase (TH)-immunoreactive fibers. The possible influence of dopaminergic (DA) fibers originating from the substantia nigra on the postnatal distribution of striatal D1 and mu receptors was also examined by producing an early 6-hydroxydopamine (6-OHDA) lesion of DA fibers. D1 and mu receptors were labeled with selective ligands: [3H]SCH 23390 and [3H]DAGO, respectively. During the first postnatal week, control rats showed patches of dense D1 binding sites in the entire rostro-caudal extension of the striatum. The localization of D1 receptor patches corresponded to striosomes identified by TH-immunoreactive islands. The striatal distribution of mu receptors was relatively homogeneous at postnatal day 0 (P0) but was clearly patchy at P3-P4. During the second postnatal week the striosomal pattern of D1 binding sites disappeared along a dorso-ventral gradient whereas mu binding sites remained distributed in patches. Densitometric measurements showed that there was a parallel increase of D1 binding sites in both striosomes and the surrounding matrix from P0 to P4. The disappearance of D1 receptor patches observed in the dorsal striatum at P9 was due to a faster increase of D1 binding sites in the matrix than in striosomes between P4 and P9 whereas a significant difference was still observed between these two compartments in the ventral striatum of P9 rats. During the third postnatal week, the density of D1 binding sites still increased but became progressively uniform in the whole striatum. The intrastriatal injection of 6-OHDA in 2-day-old rats produced a local disappearance of TH-immunoreactive fibers in the striatum and a distal degeneration of TH-immunoreactive cell bodies in the substantia nigra. However an early lesion of striatal DA fibers did not modify the pattern of development or the density of D1 binding sites during the postnatal period examined (1 and 3 weeks after the lesion). The distribution of mu receptors was unchanged 1 week after the lesion but showed a clear disorganization 3 weeks after the lesion. We discuss the differential influence of DA fibers on the distribution of D1 and mu receptors in the rat striatum and the possible role of DA in the regulation of the expression of mu receptors.     

Basal EGR-1 (zif268, NGFI-A,Krox-24) expression in developing striatal patches: role of dopamine and glutamate

Egr-1 (also known as zif268, NGFI-A, or Krox 24) is an immediate-early gene of the zinc finger family that exhibits relatively high constitutive expression in the brain, as well as inducibility by seizure activity, stimulants, and salient physiological stimuli. Immunocytochemical detection of the Egr-1 protein in the developing striatum revealed that in the late prenatal and early postnatal period, Egr-1 protein was expressed selectively in patches of striatal neurons under basal conditions. Egr-1 immunoreactivity was co-expressed with known markers of striatal patch neurons, indicating that expression was greatest in the striatal patch compartment. This patchy expression of Egr-1 transitioned to a nearly homogeneous pattern of Egr-1-immunoreactive cells by postnatal day 10, at which time most striatal neurons appeared to be Egr-1-immunoreactive. The dopamine D1 antagonist SCH23390 (0.5-1.0 mg/kg) reduced Egr-1 expression during the first week postnatal, but it was no longer effective at postnatal day 10. On the other hand, the noncompetitive NMDA antagonist MK-801 (0.5-1.0 mg/kg) became more effective at reducing Egr-1 expression with age. Neonatal destruction of nigrostriatal dopamine afferents reduced the basal pattern of Egr-1 expression for 2-3 days after the lesion, but then Egr-1 expression returned. Thus, Egr-1 expression in the developing striatum appears to be driven first by dopaminergic afferents, and then later in development by excitatory glutamatergic afferents.     

Transient and compartmental expression of the reeler gene product Reelin in the developing rat striatum

Mammalian neostriatum is composed of two neurochemically and neuroanatomically defined compartments, called the patches and matrix. The present study concerns a search for neurochemical molecules involved in formation of the striatal compartments. Using the monoclonal antibody CR-50, we here disclose a transient expression of the reeler gene product Reelin, which is known to play a crucial role in neuronal positioning and axon guidance during corticogenesis, in the developing striatum of rats. Furthermore, Reelin protein is differentially concentrated in the two distinct compartments showing a mosaic-like fashion in the early postnatal period: the compartments of heightened CR-50-immunolabeling correspond to so-called “dopamine islands” (i.e., developing striosomes) visualized by tyrosine hydroxylase (TH)-immunostaining. On the basis of these findings, we hypothesize that Reelin protein may play a role in developmental organization of the striatal compartments.     

Early loss of dopaminergic terminals in striosomes after MDMA administration to mice

The amphetamine analogue 3,4-methylenedioxymethamphetamine (MDMA or "Ecstasy") is a popular drug of abuse which causes different neurotoxic effects in the mouse compared with the rat. In mice, MDMA produces damage to striatal dopamine terminals, having little long-term effects on serotonin (5-HT) containing neurons. A relevant feature of the striatum is its striosome/matrix compartmental organization; defined by different connexions, and functions. In this study we examined the long-term effect induced by MDMA on tyrosine hydroxylase (TH) and dopamine transporter (DAT) immunoreactivity in the striosomes and matrix compartments of mouse striatum. Mice given MDMA showed significant reductions in TH and DAT immunostaining in striatum compared with control animals. Interestingly, this effect was considerably more pronounced in striosomes than in the matrix. These data provide the first evidence that striosomes and matrix compartments of the mouse striatum have differential vulnerability to MDMA and that the long-term neurotoxicity induced by MDMA in mice is primarily associated with a loss of striosomal dopamine fibres.     

Striatal neurons in striatal grafts are derived from both post-mitotic cells and dividing progenitors

Transplants of embryonic striatal tissue are characteristically heterogeneous, containing patches (P-zones) of striatal medium spiny projection neurons. It is not yet known how this morphology develops, and whether the striatal neurons in the grafts are derived from post-mitotic neuroblasts in the embryonic brain or from striatal progenitors that continue to divide after transplantation. To address this question we labelled dividing cells in the transplants with bromodeoxyuridine (BrdU), either prior to or after transplantation into the adult lesioned rat striatum. Cells for transplantation were either pre-labelled in utero by intraperitoneal (i.p.) injections of BrdU, or post-labelled after transplantation by i.p. injections to the hosts. Either two or six months after transplantation the brains were processed using double immunohistochemical techniques to detect BrdU and calbindin-positive neurons in the transplants. In the transplants pre-labelled with BrdU, approximately 30% of calbindin-positive cells were heavily labelled with BrdU, suggesting these had undergone a final division prior to transplantation. In transplants where cells had been labelled post-transplantation, approximately 17% of calbindin cells were heavily BrdU labelled. These results suggest that whereas a proportion of striatal medium spiny neurons in the striatal grafts were post-mitotic at the time of transplantation, other striatal progenitor cells can continue to divide after transplantation, and then complete an appropriate neuronal maturation programme in the adult host brain environment.     

The postnatal development of the dopamine-containing innervation of dorsal and ventral striatum: effects of the weaver gene

We report here that the pattern of loss of dopamine that occurs in the brains of adult mice carrying the autosomal recessive weaver gene is the consequence both of failed postnatal development of the dopamine-containing mesostriatal innervation and of the disappearance of the early forming dopamine-island system. For these studies, we compared the contents of dopamine extracted from 3 divisions of the striatum, the caudoputamen, nucleus accumbens, and olfactory tubercle, and from the midbrain of weaver and control littermate pups. Catecholamines were extracted from tissues dissected from serial brain slices and were separated and measured using high-performance liquid chromatography followed by electrochemical detection. The anatomical pattern formed by the catecholamine-containing innervation of the developing striatum was studied in 8-, 11-, 20-d-old, and 1.5-month-old weaver and control mice using tyrosine hydroxylase immunohistochemistry. In weaver neonates (7-8 d old), the dopamine-containing innervation of the caudoputamen is characterized by near-normal concentrations of dopamine and by a normal anatomical arrangement of dopamine islands. Subsequently, however, the weaver disease is expressed in the caudoputamen as a failure of the dopamine islands to persist and of the dopamine-containing innervation of the matrix to develop at a normal rate. Whereas the concentration of dopamine increases 4.4-fold between days 7 and 33 in normal animals, it increases only 1.6-fold in the weaver. In spite of the severe reduction of dopamine, the weaver's caudoputamen grows to near-normal size (85%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Mosaic architecture of the somatic sensory-recipient sector of the cat's striatum

The striatum is known to have a compartmental organization in which histochemically defined zones called striosomes form branched 3-dimensional labyrinths embedded within the surrounding matrix. We explored how fiber projections from cortical somatic sensory areas representing cutaneous and deep-receptor inputs are organized in relation to this striatal architecture. Areas SI and 3a were mapped electrophysiologically, and distinguishable anterograde tracers (wheat germ agglutinin-HRP and 35S-methionine) were injected into physiologically identified loci. Primary somatic sensory corticostriatal projections were confined to a small, well-defined sector in the dorsolateral corner of the ipsilateral striatum. The somatic sensory afferents were arranged according to a coherent global body map in which rostral body parts were represented more laterally than caudal body parts. Single cortical loci innervated branched and clustered striatal zones that were reminiscent of the striosomes in their range of sizes and shapes yet lay strictly within the extrastriosomal matrix. In contrast to the global orderliness of the striatal body map, there were clear examples of locally complex patterns in which functionally distinct inputs interdigitated with each other. These patterns were often, but not always, produced when corticostriatal afferents carrying different submodality types were labeled. These findings demonstrate the existence of striosome-like striatal compartments within the seemingly uniform extrastriosomal matrix. The principle of mosaic organization thus holds throughout the tissue of the somatic sensory striatum. The striatal architecture delineated here could provide the anatomical substrate for computations requiring cross-modality comparisons within the framework of an overall somatotopy. If a similar multicompartmental architecture also characterizes other striatal regions, as seems likely, it may set general constraints on the nature of associative processing within the striatum as a whole.