Compartment-specific changes in the density of choline and dopamine uptake sites and muscarinic and dopaminergic receptors during the development of the baboon striatum: a quantitative receptor autoradiographic study

Evidence for limited D1 and D2 receptor coexpression and colocalization within the dorsal striatum of the neonatal mouse

The striatum is the major input nucleus of the basal ganglia involved in reward processing, goal-directed behaviors, habit learning, and motor control. The striatum projects to the basal ganglia output nuclei via the "direct" and "indirect" pathways, which can be distinguished by their projection fields and their opposing effects on behavior. In adult animals, the functional opposition is modulated by the differential actions of D1 and D2 dopamine receptors (D1R, D2R), the expression of which is largely separated between these pathways. To determine whether a similar degree of separation exists earlier in development, we used dual-label immunohistochemistry to map dorsal-striatal D1R and D2R expression at the promoter level in postnatal day 0 (PD0) Drd1a-tdTomato/Drd2-GFP BAC transgenic mice, and at the receptor level by costaining for native D1R and D2R in wildtype (WT) PD0 animals. To assess for potential molecular interactions between D1R and D2R we also employed a recently developed proximity-ligation assay (PLA). Limited coexpression and colocalization of the D1R and D2R proteins was found in clusters of neurons endemic to the "patch" compartment as identified by costaining with tyrosine hydroxylase, but not outside these clusters. Moreover, in contrast to our recent findings where we failed to detect a D1R-D2R PLA signal in the adult striatum, in PD0 striatum we did identify a clear PLA signal for this pair of receptors. This colocalization at close proximity points to a possible role for D1R/D2R-mediated crosstalk in early striatal ontogeny.

The non-human primate striatum undergoes marked prolonged remodeling during postnatal development

We examined the postnatal ontogeny of the striatum in rhesus monkeys (Macaca mulatta) to identify temporal and spatial patterns of histological and chemical maturation. Our goal was to determine whether this forebrain structure is developmentally static or dynamic in postnatal life. Brains from monkeys at 1 day, 1, 4, 6, 9, and 12 months of age (N = 12) and adult monkeys (N = 4) were analyzed. Nissl staining was used to assess striatal volume, cytoarchitecture, and apoptosis. Immunohistochemistry was used to localize and measure substance P (SP), leucine-enkephalin (LENK), tyrosine hydroxylase (TH), and calbindin D28 (CAL) immunoreactivities. Mature brain to body weight ratio was achieved at 4 months of age, and striatal volume increased from ∼1.2 to ∼1.4 cm(3) during the first postnatal year. Nissl staining identified, prominently in the caudate nucleus, developmentally persistent discrete cell islands with neuronal densities greater than the surrounding striatal parenchyma (matrix). Losses in neuronal density were observed in island and matrix regions during maturation, and differential developmental programmed cell death was observed in islands and matrix regions. Immunohistochemistry revealed striking changes occurring postnatally in striatal chemical neuroanatomy. At birth, the immature dopaminergic nigrostriatal innervation was characterized by islands enriched in TH-immunoreactive puncta (putative terminals) in the neuropil; TH-enriched islands aligned completely with areas enriched in SP immunoreactivity but low in LENK immunoreactivity. These areas enriched in SP immunoreactivity but low in LENK immunoreactivity were identified as striosome and matrix areas, respectively, because CAL immunoreactivity clearly delineated these territories. SP, LENK, and CAL immunoreactivities appeared as positive neuronal cell bodies, processes, and puncta. The matrix compartment at birth contained relatively low TH-immunoreactive processes and few SP-positive neurons but was densely populated with LENK-immunoreactive neurons. The nucleus accumbens part of the ventral striatum also showed prominent differences in SP, LENK, and CAL immunoreactivities in shell and core territories. During 12 months of postnatal maturation salient changes occurred in neurotransmitter marker localization: TH-positive afferents densely innervated the matrix to exceed levels of immunoreactivity in the striosomes; SP immunoreactivity levels increased in the matrix; and LENK-immunoreactivity levels decreased in the matrix and increased in the striosomes. At 12 months of age, striatal chemoarchitecture was similar qualitatively to adult patterns, but quantitatively different in LENK and SP in caudate, putamen, and nucleus accumbens. This study shows for the first time that the rhesus monkey striatum requires more than 12 months after birth to develop an adult-like pattern of chemical neuroanatomy and that principal neurons within striosomes and matrix have different developmental programs for neuropeptide expression. We conclude that postnatal maturation of the striatal mosaic in primates is not static but, rather, is a protracted and dynamic process that requires many synchronous and compartment-selective changes in afferent innervation and in the expression of genes that regulate neuronal phenotypes.

Intraneuronal trafficking of G-protein-coupled receptors in vivo

In vitro studies have widely demonstrated that the abundance and availability of G-protein-coupled receptors (GPCRs) at the cell surface is regulated by the neuronal environment and is the result of complex intraneuronal trafficking. However, this regulation is still poorly understood in vivo. Modulation of receptor availability at the neuronal membrane is a key event in the regulation of neuronal functions (e.g. neurotransmitter release or neuronal excitability in physiological, pathological or therapeutic conditions). We discuss the effects of duration of receptor stimulation (acute versus chronic) on the intraneuronal trafficking of GPCRs in vivo, and we show that this trafficking might differ according to subcellular compartment (soma, dendrites or axon terminals).

Neurobiology of Tourette's syndrome: concepts of neuroanatomic localization and neurochemical abnormalities

Despite a preponderance of evidence suggesting an organic rather than psychogenic origin for Tourette syndrome, the precise neurobiological abnormality remains speculative. Neuroanatomically, there is expanding confirmation that cortico-striato-thalamo-cortical pathways represent the site of origin for tics and accompanying neuropsychiatric problems. Pathophysiological hypothesis are generally defined based on involvement of (1) a specific anatomical site (striato-thalamic circuits, striatal compartments), (2) physiologic abnormality (excess thalamic excitation, impaired intracortical inhibition), or (3) involvement of a specific neurotransmitter or synaptic component. This review provides information essential for understanding current and future proposals pertaining to the neurobiology of this intriguing disorder.

Regulation of the subcellular distribution of m4 muscarinic acetylcholine receptors in striatal neurons in vivo by the cholinergic environment: evidence for regulation of cell surface receptors by endogenous and exogenous stimulation

Our aim was to determine how the cholinergic environment influences, in vivo, the membrane abundance and the intracellular trafficking of the muscarinic receptor m4 (m4R). Immunohistochemistry at light and electron microscopic level was used to detect the subcellular localization of m4R in several populations of striatal cholinoceptive neurons, including cholinergic neurons and medium spiny neurons. (1) In control rats, in cholinergic neurons, m4R is mostly restricted to intracytoplasmic sites involved in its synthesis, especially endoplasmic reticulum. In contrast, m4R is preferentially located at the plasma membrane in cell bodies and dendritic shafts and spines of medium spiny neurons. The density of m4R was greater at the membrane of perikarya in patches (striatal areas with low acetylcholine activity) than in matrix (striatal areas with high acetylcholine activity). (2) Stimulation of muscarinic receptor with oxotremorine provokes translocation of m4R from the membrane to endosomes in perikarya and dendrites of medium spiny neurons but has no influence on the localization of m4R in the cytoplasm of cholinergic cell bodies. Our results suggest that the intraneuronal trafficking and the abundance of membrane-bound m4R in vivo is under regulation of the cholinergic environment. The m4R subcellular compartmentalization depends on the phenotype of the cholinoceptive neuron and on its neurochemical environment. Such regulation, by modulating availability of receptor for endogenous and exogenous ligands, may play key roles in the response of target neurons.

Ontogeny of the striatal neurons expressing the D2 dopamine receptor in humans: an in situ hybridization and receptor-binding study

D2 dopamine receptor (D2R) gene expression was analyzed by in situ hybridization and D2R ligand autoradiography in the human striatum during ontogeny. D2R mRNA and ([3H]YM-09151-2)-binding sites were detected in the striatum from week 12 of fetal life. At this time, D2R mRNA and binding sites were predominant in the putamen and occurred in a pattern of clusters. D2R-binding sites displayed a similar pattern. The signal in the caudate nucleus was weak from weeks 12 to 16. From week 20 of fetal life, D2R mRNA and D2R-binding sites signals became intense in the ventral striatum. At birth, D2R mRNA became homogeneously distributed while D2R-binding sites kept an heterogeneously distribution. Comparative topological and temporal analysis of the D2R, enkephalin and D1 dopamine receptor (D1R) mRNAs showed a distinct developmental pattern for each mRNA. Before birth, the neurons expressing enkephalin and D1R mRNAs were preferentially distributed in the matrix and in the striosomes, respectively, while the neurons expressing D2R mRNA did not display a preferential localization. At birth, high levels of enkephalin mRNA were restricted to the matrix; D1R mRNA level was homogeneous throughout the striatum. D2R mRNA was heterogeneously distributed in the whole striatum with high signals located both in the striosomes and the matrix. These results demonstrate that functional D2R are expressed as early as week 12 in the striatum with a heterogeneous distribution. Our findings also demonstrate that, in contrast to what was expected from similar studies in rodents, D2R mRNA and enkephalin mRNA do not display identical, overlapping expression patterns in striatal neurons during human ontogeny.

D1 and D2 dopamine receptors in perinatal and adult basal ganglia

There is reason to believe that dopamine is important in developmental programs of the basal ganglia, brain nuclei implicated in motor and cognitive processing. Dopamine exerts effects through dopamine receptors, which are predominantly of the D1 and D2 subtypes in the basal ganglia. Cocaine acts as a stimulant of dopamine receptors and may cause long-term abnormalities in children exposed in utero. Dopamine receptor (primarily D1) stimulation has been linked to gene regulation. Therefore, D1 and D2 receptor densities in perinatal and adult striatum and globus pallidus were examined using quantitative autoradiography. The most striking finding was that pallidal D1 receptor densities were 7-15 times greater in the perinatal cases than in the adult. Pallidal D2 receptor densities were similar at both ages. In both the adult and perinatal striatum, D2 receptor densities were greater in the putamen than in the caudate, and both D1 and D2 receptor densities were modestly enriched in caudate striosomes compared with the matrix. In both caudate and putamen, perinatal D1 receptor levels were within the adult range, whereas D2 receptor levels were only 50% of adult values. The development of D1 and D2 receptors appears to vary across the major subdivisions of the human basal ganglia. The facts that we found such extremely high levels of D1 receptors in the perinatal pallidum, and that D1 receptor activation influences gene regulation, suggest that the globus pallidus could be particularly susceptible to long-term changes with perinatal exposure to cocaine and other D1 receptor agonists or antagonists.

Differential maturation of cholinergic interneurons in the striatal patch versus matrix compartments

Striatal neurons are generated in two distinct phases. Neurons that become postmitotic early in embryonic development come to be located primarily in the patch compartment of the striatum, while the majority of the neurons situated in the striatal matrix compartment are generated later in embryogenesis. The cholinergic interneurons in the striatum, which have been reported to be more or less homogeneously distributed in the adult, are all generated early in development. Given that early generated neurons are expected to be situated primarily in the patch compartment, we investigated the apparently homogeneous distribution of cholinergic neurons by analysing their localizations in the patch and matrix compartments during striatal development. To selectively mark the striatal patch compartment we made injections of the retrograde fluorescent tracer True Blue in the substantia nigra on embryonic day 20 or postnatal day (P)1, and then stained for cholineacetyltransferase (ChAT) at different time-points in development. After P7, the distribution of the ChAT positive neurons changes from an earlier preference for the patch compartment to a preference for an area of the matrix just outside of the patches. Absolute counts show that this change in distribution is caused mainly by a late turn on of ChAT by the cholinergic neurons in the matrix compartment. These data suggest that there are different compartmental subpopulations of cholinergic neurons in the striatum.

Functional and molecular differentiation of the dopamine system induced by neonatal denervation

The administration of the neurotoxin 6-hydroxydopamine (6-OHDA) to damage the mesostriatal dopamine (DA) system in the neonate results in different neurochemical and behavioral consequences as compared to lesions made in adulthood. There have been few direct data to support the conclusion that the behavioral changes following neonatal 6-OHDA lesions reflect plasticity of the DA system. It is our hypothesis that the plasticity of the developing DA system is fundamentally different from that of the adult. Responses to 6-OHDA lesions can only be understood within the context of the status of the mesostriatal DA system at the time of the lesion. There are stages of development in the early postnatal period when certain components of the mesostriatal DA system are differentially sensitive to 6-OHDA lesions. These "windows" of vulnerability can be predicted from an analysis of the developmental expression of DA receptors and the maturation of the subpopulation of the mesostriatal DA system that innervates them. We review the differences in the behavioral plasticity of the adult and neonate sustaining 6-OHDA lesions to the mesostriatal DA system, the mechanisms responsible for the behavioral plasticity in the adult, and our conceptualization of which mechanisms are affected in the neonate.

The distribution of cholinergic perikarya with respect to enkephalin-rich patches in the caudate nucleus of the adult cat

The distribution of cholinergic interneurons with respect to enkephalin-rich patches in the caudate nucleus of the cat was examined using both computer-assisted 3-D reconstruction and immunocytochemical techniques. Examination of the 3-D distribution of perikarya staining for choline acetyltransferase (ChAT) revealed that these cells were not evenly distributed within the caudate nucleus but exhibited areas of increased and decreased density. Comparison of the 3-D distribution of cholinergic perikarya to that of the enkephalin-rich patches indicated that areas of increased ChAT+ cell density often corresponded to the positions of enkephalin-rich patches within the dorsal-lateral caudate nucleus. At more ventral regions, there was no clear correspondence between areas of increased ChAT+ cell density and enkephalin-rich patches. In agreement with these observations, a quantitative analysis of sections double-labeled for ChAT and enkephalin revealed that the density of cholinergic neurons within enkephalin-rich patches was twice that in the surrounding tissue in the dorsal region of the caudate nucleus. In contrast at more ventral levels, the difference in the density of ChAT+ cells in enkephalin-rich patches did not significantly differ from that in the surrounding striatal tissue. Both the results of the 3-D and the double-labeling analysis suggest that cholinergic neurons are not evenly distributed within the caudate nucleus of the cat but form loose clusters which are associated dorsally with the enkephalin-rich patches. These results also provide further evidence of heterogeneity within the striosomal compartment in the cat.

Neurobiological issues in Tourette syndrome

The Tourette syndrome (TS) represents an intriguing disorder that overlaps the clinical fields of neurology and psychiatry. Composed of a spectrum of familial, involuntary motor and vocal tics and co-morbid neuropsychological problems, this disorder has become a model for investigators interested in neurobehavioral research. Although the subject of numerous reports since Tourette's original description in 1885, over the past decade there has been a rapid expansion of knowledge pertaining to the phenomenology of tic syndromes and their associated problems, the role of genetic and environmental factors, and the underlying pathophysiology. The role of frontal-subcortical circuits, dopaminergic neurotransmission, and second messenger systems are highlighted. This report provides a framework for understanding current neurobiological issues in TS.

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-D28k-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.

Synaptic neurochemistry of human striatum during development: changes in sudden infant death syndrome

There is evidence of abnormalities in the brain-stem monoamine-containing neurons in infants with sudden infant death syndrome (SIDS). By taking advantage of the rich innervation of the human basal ganglia by monoaminergic afferents from cell bodies in the brainstem, we studied the synaptic chemistry of catecholamine and associated neurons of the putamen obtained postmortem from 14 SIDS infants, eight age-matched control infants, and older control subjects of various ages. We found significantly lower concentrations of dopamine and higher homovanillic acid/DA ratios in samples from SIDS infants compared with age-matched control infants. Noradrenaline and 5-hydroxytryptamine were lower in SIDS compared with control subjects, but the difference did not reach statistical significance. There was no clear evidence that dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid were altered. Immunoblot analysis of striatal tissue showed that samples from infants with SIDS, which exhibited lower DA, also had lower tyrosine hydroxylase protein. Other transmitter-specific neuronal markers were also assessed, including enzymes associated with cholinergic and GABA-containing neurons. We found significantly decreased choline acetyltransferase activities. However, GABA, glutamate, or somatostatin concentrations or monoamine oxidase activities were unchanged in SIDS. We also noted age-dependent changes in brain weights and some synaptic markers by comparing the age-matched infants with older control subjects. Analysis of variance revealed that homovanillic acid, dihydroxyphenylacetic acid, and monoamine oxidase B activities were increased with age. DA and choline acetyltransferase were also found to be positively correlated in putamen. Our findings suggest developmental changes in some transmitter-specific neurons in SIDS that may result from apneic episodes or chronic hypoxia induced before death.

High-affinity choline transport sites: use of [3H]hemicholinium-3 as a quantitative marker

High-affinity choline transport (HAChT), the rate-limiting and regulatory step in acetylcholine (ACh) synthesis, is selectively localized to cholinergic neurons. Hemicholinium-3 (HC3), a potent and selective inhibitor of HAChT, has been used as a specific radioligand to quantify HAChT sites in membrane binding and autoradiographic studies. Because both HAChT velocity and [3H]HC3 binding change as in vivo activity of cholinergic neurons is altered, these markers are also useful measures of cholinergic neuronal activity. Evidence that [3H]HC3 is a specific ligand for HAChT sites on cholinergic terminals is reviewed. The ion requirements of HAChT and [3H]HC3 binding indicate that sodium and chloride are required for recognition of both choline and [3H]HC3. A common recognition site is also indicated by the close correspondence of the potency of HC3 and choline analogues for inhibiting both HAChT and [3H]HC3 binding. The parallel regional distributions of both markers in adult brain, during development and after specific lesions, all indicate specific cholinergic localization. The close association of HAChT and [3H]HC3 binding sites is also supported by parallel regulatory changes occurring after in vivo drug treatments and in vitro depolarization. Overall, the data indicate a close association between HAChT and [3H]HC3 binding and are consistent with the sites being identical. Methodologic considerations in using [3H]HC3 as a ligand and considerations in interpretation of results are also discussed.

The dopamine hypothesis of schizophrenia: limbic interactions with serotonin and norepinephrine

The "dopamine hypothesis" of schizophrenia has been the predominant guiding theoretical construct for driving studies of the neurobiology of schizophrenia. There has, however, been much interest in the contributions of non-dopamine systems to the clinical symptoms of schizophrenia, in particular, norepinephrine and serotonin. However, direct evidence for altered transmission in monoamine systems has been quite limited. In part this reflects a focus on specific brain regions for different transmitters, in contrast to a "neural systems" approach. Thus, evidence for the dopamine hypothesis has been derived from studies of the basal ganglia in schizophrenic cases and infrequently from other (e.g. cortical) regions. Recent studies have suggested that disturbances in the organization or development of the temporal lobe may underlie certain aspects of the symptoms of schizophrenia In particular, the hippocampus may show cellular loss or disturbances in cell orientation. These results are supported by the work that has identified neuropsychological and in vivo brain disturbances in schizophrenia specific to the medial temporal lobe. However, not all cases show such pathology and it is likely that these disorders could, in addition, involve an important afferent and/or efferent system associated with the temporal lobe. This model is based on the currently held view that parallel cortico-striatal-pallidal-thalamo circuits form an important basis for information processing in the brain. One such circuit involves the primary efferent of the hippocampus, the subiculum, and associated cortical regions that project onto the ventral striatum. Many of the cortical regions that project directly to the ventral striatum also project to the hippocampus via the entorhinal cortex. These include the anterior cingulate, posterior cingulate, superior temporal cortex, and inferior temporal cortex. The ventral striatum, made up of the nucleus accumbens, olfactory tubercle, and ventral putamen, has as its target the ventral pallidum. The ventral pallidum projects to the medial dorsal nuclei of the thalamus, which, in turn, projects to the anterior prefrontal cortical area. This loop has been referred to as the limbic loop. The patterns of innervation and expression of monoamine receptors in the brain have been delineated for the non-human primate and are being unraveled in the human. We, and other, have described the patterns of receptor expression in the limbic circuit. However, few studies have been published to date that detail what the neurochemical counterparts of the neuronal and neuropsychological disturbances in the limbic circuit might be. We have explored the possibility that monoamine systems are altered at more than one synaptic station in this circuit.(ABSTRACT TRUNCATED AT 400 WORDS)

Compartmentalization of excitatory amino acid receptors in human striatum

Division of the mammalian neostriatum into two intermingled compartments called striosomes and matrix has been established by analysis of enzyme activity, neuropeptide distribution, nucleic acid hybridization, and neurotransmitter receptor binding. Striosomes and matrix are distinct with respect to afferent and efferent connections, and these regions provide the potential for modulation and integration of information flow within basal ganglia circuitry. The primary neurotransmitters of corticostriatal afferents are excitatory amino acids, but to date no correlation of excitatory amino acid receptors and striatal compartments has been described. We examined binding to the three pharmacologically distinct ionotropic excitatory amino acid receptors, N-methyl-D-aspartate, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, and kainate, in human striatum using in vitro receptor autoradiography and compared the binding to striosomes and matrix histochemically defined by acetylcholinesterase activity. Our findings reveal increased binding to N-methyl-D-aspartate receptors and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors in matrix relative to striosomes and increased kainate receptor binding in striosomes relative to matrix. These results suggest that afferent input to the two striatal compartments may be mediated by pharmacologically distinct excitatory amino acid receptor subtypes.

Development of high-affinity choline transport sites in rat forebrain: a quantitative autoradiography study with [3H]hemicholinium-3

The development of cholinergic terminals in rat brain has been quantitatively analyzed by [3H]hemicholinium-3 autoradiography. [3H]Hemicholinium-3 binds to high affinity choline transport sites, a specific marker for cholinergic neurons. In neonatal animals, kinetic and pharmacologic binding characteristics and regional distribution of [3H]hemicholinium-3 sites are consistent with specific cholinergic localization, as in the adult. The distribution of cholinergic terminals is described in the adult rat brain and during development, including heterogeneity of binding within several regions such as the striatum, nucleus accumbens, olfactory tubercle, cortex, and hippocampus. Early development and maturation vary greatly between brain regions. At embryonic day E18 and day 0, specific binding density is high only in the medial habenula. Development occurs primarily during the postnatal period in most brain regions examined. Many brain regions exhibit a lull in development between days 5 and 10, although the rate of development is highly region specific. Specific binding increases 2-12-fold between day 5 and adult animals, with adult density being achieved anywhere from day 15 to after day 21. The ontogeny of [3H]hemicholinium-3 binding sites generally occurs in a rostral to caudal direction. In the striatal body the characteristic lateral to medial gradient of binding site density is apparent by day 5, and development is more rapid in the lateral striatum. Patches of dense [3H]hemicholinium-3 binding coincident with acetylcholinesterase are observed on day 5 in the caudal striatum. The various patterns of cholinergic terminal development suggest that factors regulating cholinergic development are regional and complex.

Ontogeny of cholecystokinin receptors in the human striatum

The distribution of cholecystokinin binding sites was studied by receptor autoradiography in the human striatum at midgestation, birth and adulthood. In the adult, cholecystokinin receptors are inhomogeneously distributed with patches of reduced labeling. In the caudate nucleus but not in the putamen these patches match the striosomal organization as revealed by acetylcholinesterase staining. At midgestation, patches of high density of cholecystokinin receptors are in register with the dopamine D1 receptor-enriched striosomes. At birth, this striosomal organization has already evolved into the adult pattern of higher matrix level in contrast to the striosomal pattern of acetylcholinesterase staining.

Heterogeneous development of calbindin-D28K expression in the striatal matrix

In the present study, we attempted to trace the development of the striatal matrix by analyzing the ontogenetic expression of calbindin-D28K (calbindin), a calcium binding protein selectivity expressed in medium-sized neurons of the matrix compartment of the mature rat's caudoputamen. The localization of calbindin was documented in a series of developing rat brains, as was the compartmental location of these cells relative to tyrosine hydroxylase (TH)-immunostained dopamine islands, sites of future striosomes. Medium-sized striatal neurons appeared in the striatum at embryonic day (E) 20, and from their first appearance, the calbindin-positive neurons had highly heterogeneous distributions. They first formed a latticework of patches and bands in a ventral region of the caudoputamen. By postnatal day (P) 7, this early calbindin-positive lattice had evolved into a mosaic in which circumscript pockets of low calbindin-like immunoreactivity appeared in more extensive calbindin-rich surrounds. With further development, the mosaic gradually encroached on all but the dorsolateral caudoputamen, a district that is calbindin-poor at adulthood. A special lateral branch of the striatal calbindin system was also identified, distinct from the rest of the calbindin-positive mosaic in several developmental characteristics. In the parts of the caudoputamen where the developing calbindin system and dopamine island system were both present, the dopamine islands invariably lay in calbindin-poor zones. Most dopamine islands, however, only filled parts of the corresponding calbindin-poor zones. Moreover, there were some calbindin-poor zones for which TH-positive dopamine islands could not be detected. Thus during development, calbindin was expressed in the extrastriosomal matrix of the striatum, but the matrix could be divided into calbindin-rich and calbindin-poor zones. In the calbindin-rich regions, there were patches of especially intense calbindin expression and zones of weaker expression. These results suggest that there is neurochemical heterogeneity in the striatal matrix during the prolonged developmental period in which the early calbindin-positive lattice expands to form the calbindin-positive matrix of the mature striatum. Surprisingly, calbindin expression in the matrix, although eventually distributed in strictly complementary fashion to striosomes, does not originate as a system complementary to dopamine islands. The prolonged disparity between the borders of dopamine islands and calbindin-poor zones, and the different spatiotemporal schedules of development of the islands and the calbindin gaps suggest instead that the final match between the borders of striosomes and surrounding matrix results from dynamic processes occurring early in postnatal development. Candidate mechanisms for the gradual adjustment of these borders are proposed.

Receptor alterations in manganese intoxicated monkeys

The density of four different receptors and one marker of dopamine uptake sites were analyzed in monkey brains after manganese exposure (0.1 g manganese per month during 26 months, a dose comparable to that workers might inhale in dusty environments) by means of quantitative receptor autoradiography. The binding of 3H-mazindol to the dopamine uptake sites was reduced by 75% in both the head of the caudate nucleus and putamen, while it remained unchanged in the other regions analyzed. The binding of the D1 receptor ligand 3H-SCH 23,390 was reduced about 45% in the same areas as mazindol binding, while the density of D2 receptors was unaffected. The muscarinic acetylcholine receptors as well as GABAA receptors remained also unchanged in all brain areas analyzed after manganese exposure. Thus the dopaminergic neurons must be considered to be vulnerable to manganese concentrations attainable in the work environment. Our results also indicate that postsynaptic structures containing D1 receptors are sensitive while cells containing D2 receptors are either spared or compensated for by up-regulation of the number of receptors on remaining sites.

Ontogeny of gene expression of adenosine A2 receptor in the striatum: early localization in the patch compartment

The ontogeny of adenosine A2 receptor mRNA and adenosine A2 binding sites distributions was studied by in situ hybridization histochemistry and receptor autoradiography in pre- and post-natal rat striatum, postnatal dog striatum, and a human fetus striatum and compared to that of dopamine D1 and mu opiate receptors. The early postnatal striatum demonstrated heterogeneous distributions of adenosine A2 receptor mRNA and adenosine A2 binding sites with patches of dense labeling corresponding to dopamine D1 and mu opiate receptors enriched zones. This patchy pattern evolved to the homogeneous distribution observed in the adult. The higher intensity of adenosine A2 receptor mRNA enriched patches correspond at the microscopical level to a higher density of labeled neurons in the patches areas and also to a higher level of expression per labeled patches neuron than in the matrix ones. This demonstrates for the first time that differences in patch/matrix receptor density is at least partly linked to different levels of receptor gene expression.

The effect of intrastriatal application of directly and indirectly acting dopamine agonists and antagonists on the in vivo release of acetylcholine measured by brain microdialysis

The effect of intrastriatal application of D-1, D-2 and indirect dopaminergic drugs on the release of striatal acetylcholine as a function of the post-implantation intervals was studied using in vivo microdialysis. The dopamine D-2 agonists LY 171555 and (-)N0437 inhibited the release of striatal acetylcholine to 40% of control values 16-24 h after implantation of the dialysis cannula. When LY 171555 was infused 40-48 h after implantation of the dialysis cannula, the response was attenuated to 20% of control values. Meanwhile, the effectiveness of infusions of the antagonists (-)sulpiride and haloperidol was augmented from a non significant effect at 16-24 h to a 150% increase 40-48 h after implantation of the cannula. Infusions of the dopamine releasing agent amphetamine or the dopamine uptake inhibitor nomifensine resulted in a dose-dependent increase in the overflow of dopamine. Not until a sevenfold increase in the level of dopamine was seen, the release of acetylcholine was significantly affected. This hyporesponsiveness of the striatal cholinergic interneurons to endogenous dopamine could not be attributed to dopamine D-1 receptor activation, since no effects on striatal acetylcholine release were found by intrastriatal infusions of the selective D-1 agonist CY 208-243 or the selective D-1 antagonist SCH 23390. The results indicate that dopamine D-2 receptors are involved in the regulation of striatal acetylcholine release and that these receptors are tonically occupied by endogenous dopamine under the present experimental conditions 40-48 h after probe implantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ontogeny of dopamine D1 and D2 receptor subtypes in rat basal ganglia: a quantitative autoradiographic study

The ontogeny of D1 and D2 dopamine (DA) receptors in rat basal ganglia was examined by quantitative autoradiography using the iodinated ligands [125I]SCH 23982 and [125I]iodobenzamide [( 125I]IBZM), respectively. Temporal and spatial differences in the development of the receptor subtypes were observed. Scatchard transformation of saturation isotherms conducted at postnatal day 10 (P10) and P60, showed that there was no age-related change in the affinity of [125I]SCH 23982 binding to D1 receptors (Kd = 2.6 nM) but there was a significant increase in the Bmax (771 compared to 2032 fmol/mg protein, P = 0.002). A statistically significant difference in Kd was noted between ages P10 and P60 for [125I]IBZM labelling of D2 receptors (0.62 vs 1.00 nM, respectively, P less than 0.01). A significant increase in the Bmax (211 and 721 fmol/mg protein, P less than 0.01) was also observed. D1 receptors were visible as distinct patches at P1. The highest density was found in the ventrolateral caudate-putamen (CPu). By P5 the patches were found in all subregions of the CPu and nucleus accumbens. Between P7 and P10 the binding became distinctly less patchy due to a marked increase in the density of D1 receptors in non-patch (matrix) regions. Adult levels of receptor were seen by P30. The concentration of DA (measured by HPLC) and binding of [3H]mazindol to DA uptake sites in whole striatum showed similar and nonlinear increases with age. The age-related change in the topography of binding sites for [3H]mazindol was similar to that of D1 receptors at the same ages. Both D2 receptors and [3H]hemicholinium-3 (HC-3) binding to high affinity transport sites for choline developed initially in the dorso-lateral CPu. Their topography was largely overlapping but distinct from that of the D1 receptor. D2 receptors were not consistently observed until P3 in the CPu, and zones of enriched binding were aligned with zones of low density for D1 receptors. The density of D2 receptors reached adult levels by P30. The differential development of the DA receptors was also evident in the substantia nigra (SN) and globus pallidus (GP). D1 receptors were found in SN prior to the appearance of D2 receptors and throughout development the density was greater in pars reticulata than in pars compacta, whereas the density of D2 receptors was higher in the pars compacta. At all ages the density of D1 receptors was greater than the density of D2 receptors in the GP and reached adult levels before reaching it in the CPu or SN.(ABSTRACT TRUNCATED AT 400 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.

Role of dynorphin-containing neurons in the presynaptic inhibitory control of the acetylcholine-evoked release of dopamine in the striosomes and the matrix of the cat caudate nucleus

The roles of acetylcholine and dynorphin (1-13) in the presynaptic control of the release of [3H]dopamine continuously synthesized from [3H]tyrosine were examined in a prominent striosomal enriched area and in an adjacent matrix enriched area of the cat caudate nucleus. This was achieved using microsuperfusion devices applied vertically onto coronal slices of cat brain. These devices were placed in a striosomal enriched area located in the core of the structure (acetylcholinesterase-poor zone) and in an adjacent matrix enriched area (acetylcholinesterase-rich zone). [3H]Tyrosine was delivered continuously to each microsuperfusion device and [3H]dopamine released was estimated in the superfusate. As previously shown, in the presence of tetrodotoxin (1 microM), acetylcholine (50 microM) induces a prolonged stimulation of [3H]dopamine release in both compartments through an interaction with muscarinic receptors. Our present study indicates that both dynorphin 1-13 (1 microM) and the selective kappa agonist trans-3,4-dichloro-N-methyl-N[2-(1-pyrrolidinyl)cyclohexyl]benzeneace tamine (U50488) (1 microM) inhibit the tetrodotoxin-resistant acetylcholine-evoked release of [3H]dopamine, these effects being slightly more pronounced in the matrix than in the striosomal enriched area. Naloxone (1 microM) reversed the inhibitory effect of U50488 in both areas. These results suggest that dynorphin exerts an inhibitory presynaptic control of dopamine release through kappa opioid receptors located on dopamine nerve terminals in the striosome as well as in the matrix. However, the presynaptic cholinergic control of dopamine release is much more complex in the matrix than in the striosomal enriched area. Besides its tetrodotoxin-resistant stimulatory effect, acetylcholine exerts two opposing tetrodotoxin-sensitive effects on [3H]dopamine release, one facilitatory and the other inhibitory. We demonstrate here that in the superfused matrix enriched area, the indirect acetylcholine inhibitory response is mediated by dynorphin-containing neurons. Indeed, the short-lasting stimulatory effect of acetylcholine on [3H]dopamine release was converted into a long-lasting response in the presence of naloxone (1 microM), and, in this latter condition, the co-application of dynorphin 1-13 (1 microM) restored the short-lasting stimulatory effect.

Striosomal organization of cholinergic and dopaminergic uptake sites and cholinergic M1 receptors in the adult human striatum: a quantitative receptor autoradiographic study

The distribution of cholinergic pre- and postsynaptic markers and dopaminergic presynaptic markers was analyzed in the adult human striatum, using quantitative receptor autoradiography. The distribution of the different binding sites indicates that cholinergic and dopaminergic uptake sites display a striosomal organization, with a higher binding site density in the striatal matrix. M1 muscarinic cholinergic receptor distribution parallels the distribution of cholinergic presynaptic markers. Our data show that cholinergic and dopaminergic terminals, and M1 receptors are enriched in the matrix of the adult human striatum.