Two years changes in the development of caudate nucleus are involved in restricted repetitive behaviors in 2-5-year-old children with autism spectrum disorder

Caudate nucleus volume is enlarged in autism spectrum disorder (ASD) and is associated with restricted and repetitive behaviors (RRBs). However, the trajectory of caudate nucleus volume in RRBs of young children remains unclear. Caudate nucleus volume was measured in 36 children with ASD and 18 matched 2-3-year-old subjects with developmentally delayed (DD) at baseline (Time 1) and at 2-year follow-up (Time 2). The differential growth rate in caudate nucleus volume was calculated. Further, the relationships between the development of caudate nucleus volume and RRBs were analyzed. Our results showed that caudate nucleus volume was significantly larger in the ASD group at both time points and the magnitude of enlargement was greater at Time 2. The rate of caudate nucleus growth during this 2-year interval was faster in children with ASD than DD. Right caudate nucleus volume growth was negatively correlated with RRBs. Findings from this study suggest developmental abnormalities of caudate nucleus volume in ASD. Longitudinal MRI studies are needed to explore the correlation between atypical growth patterns of caudate nucleus and phenotype of RRBs.

Behavioral effects of dopamine receptor inactivation in the caudate-putamen of preweanling rats: role of the D2 receptor

RATIONALE

Inactivating dopamine (DA) receptors in the caudate-putamen (CPu) attenuates basal and DA agonist-induced behaviors of adult rats while paradoxically increasing the locomotor activity of preweanling rats.

OBJECTIVE

The purpose of this study was to determine (a) whether D1 or D2 receptor inactivation is responsible for the elevated locomotion shown by preweanling rats and (b) whether DA receptor inactivation produces a general state in which any locomotor-activating drug will cause a potentiated behavioral response.

METHODS

Dimethyl sulfoxide (DMSO) or N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) was bilaterally infused into the CPu on postnatal day (PD) 17. In experiment 1, DA receptors were selectively protected from EEDQ-induced alkylation by pretreating rats with D1 and/or D2 antagonists. On PD 18, rats received bilateral microinjections of the DA agonist R(-)-propylnorapomorphine into the dorsal CPu, and locomotor activity was measured for 40 min. In subsequent experiments, the locomotion of DMSO- and EEDQ-pretreated rats was assessed after intraCPu infusions of the selective DA agonists SKF82958 and quinpirole, the partial agonist terguride, or after systemic administration of nonDAergic compounds.

RESULTS

Experiment 1 showed that EEDQ's ability to enhance the locomotor activity of preweanling rats was primarily due to the inactivation of D2 receptors. Consistent with this finding, only drugs that directly or indirectly stimulated D2 receptors produced a potentiated locomotor response in EEDQ-treated rats.

CONCLUSIONS

These results show that DA receptor inactivation causes dramatically different behavioral effects in preweanling and adult rats, thus providing additional evidence that the D2 receptor system is not functionally mature by the end of the preweanling period.

Impact of early vs. late childhood early life stress on brain morphometrics

Previous studies of early life trauma suggest that in addition to its emotional impact, exposure to early life stress (ELS) is associated with alterations in brain structure. However, little attention has been devoted to the relationship between emotional processing and brain integrity as a function of age of ELS onset. In the present study we examined whether ELS onset in older ages of youth rather than younger ages is associated with smaller limbic and basal ganglia volumes as measured by magnetic resonance imaging (MRI). We hypothesized that later age of manifestation during youth is associated with smaller volumetric morphology in limbic and basal ganglia volumes in adulthood. A total of 173 individuals were divided into three groups based on the age of self-reported ELS. The three groups included individuals only experiencing early childhood ELS (1 month-7 years, n = 38), those only experiencing later childhood ELS (8 years -17 years, n = 59), and those who have not experienced ELS (n = 76). Anterior cingulate cortex (ACC), hippocampus, amygdala, insula and caudate volumes were measured using a T1-weighted MRI. Analyses confirmed that later childhood ELS was associated with volumetric reductions in the ACC and insula volumes, while ELS experienced between the ages of 1 month and 7 years was not associated with lower brain volumes in these regions. The results may reflect the influence of more fully developed emotional processing of ELS on the developing brain and reinforce a body of research implicating both the ACC and insula in neuropsychiatric disorders and emotional regulation.

Expression profiles of mitochondrial genes in the frontal cortex and the caudate nucleus of developing humans and mice selectively bred for high and low fear

A growing body of evidence suggests that mitochondrial function may be important in brain development and psychiatric disorders. However, detailed expression profiles of those genes in human brain development and fear-related behavior remain unclear. Using microarray data available from the public domain and the Gene Ontology analysis, we identified the genes and the functional categories associated with chronological age in the prefrontal cortex (PFC) and the caudate nucleus (CN) of psychiatrically normal humans ranging in age from birth to 50 years. Among those, we found that a substantial number of genes in the PFC (115) and the CN (117) are associated with the GO term: mitochondrion (FDR qv <0.05). A greater number of the genes in the PFC (91%) than the genes in the CN (62%) showed a linear increase in expression during postnatal development. Using quantitative PCR, we validated the developmental expression pattern of four genes including monoamine oxidase B (MAOB), NADH dehydrogenase flavoprotein (NDUFV1), mitochondrial uncoupling protein 5 (SLC25A14) and tubulin beta-3 chain (TUBB3). In mice, overall developmental expression pattern of MAOB, SLC25A14 and TUBB3 in the PFC were comparable to the pattern observed in humans (p<0.05). However, mice selectively bred for high fear did not exhibit normal developmental changes of MAOB and TUBB3. These findings suggest that the genes associated with mitochondrial function in the PFC play a significant role in brain development and fear-related behavior.

Caudate asymmetry: a neurobiological marker of moderate prenatal alcohol exposure in young adults

This study identified structural changes in the caudate nucleus in offspring of mothers who drank moderate levels of alcohol during pregnancy. In addition, the effect of duration of alcohol use during pregnancy was assessed. Young adults were recruited from the Maternal Health Practices and Child Development Project. Three groups were evaluated: prenatal alcohol exposure (PAE) during all three trimesters (3T), PAE during the first trimester only (1T), and controls with no PAE (0T). Magnetic resonance images were processed using the automated labeling pathway technique. Volume was measured as the number (gray+white) and relative percentage (caudate count/whole brain count x 100) of voxels. Asymmetry was calculated by subtracting the caudate volume on the left from the right and dividing by the total (L-R/L+R). Data analyses controlled for gender, handedness, and prenatal tobacco and marijuana exposures. There were no significant differences between the groups for whole brain, left, or right volumes. There was a dose-response effect across the three exposure groups both in terms of magnitude and direction of asymmetry. In the 3T group, the left caudate was larger relative to the right caudate compared to the 0T group. The average magnitude of caudate asymmetry for the 1T group was intermediate between the 0T and 3T groups. Subtle anatomical changes in the caudate are detected at the moderate end of the spectrum of prenatal alcohol exposure.

The development of the basal ganglia in Capuchin monkeys (Cebus apella)

The basal ganglia are subcortical structures involved in the planning, initiation and regulation of movement as well as a variety of non-motor, cognitive and affective functions. Capuchin monkeys share several important characteristics of development with humans, including a prolonged infancy and juvenile period, a long lifespan, and complex manipulative abilities. This makes capuchins important comparative models for understanding age-related neuroanatomical changes in these structures. Here we report developmental volumetric data on the three subdivisions of the basal ganglia, the caudate, putamen and globus pallidus in brown capuchin monkeys (Cebus apella). Based on a cross-sectional sample, we describe brain development in 28 brown capuchin monkeys (male n=17, female n=11; age range=2months-20years) using high-resolution structural MRI. We found that the raw volumes of the putamen and caudate varied significantly with age, decreasing in volume from birth through early adulthood. Notably, developmental changes did not differ between sexes. Because these observed developmental patterns are similar to humans, our results suggest that capuchin monkeys may be useful animal models for investigating neurodevelopmental disorders of the basal ganglia.

Neurodevelopment of C57B/L6 mouse brain assessed by in vivo diffusion tensor imaging

Heterogeneous spatiotemporal patterns of C57B/L6 murine brain maturation during the first 7 weeks after birth (i.e. P15 to P45) were assessed in vivo by diffusion tensor imaging (DTI) at 9.4 T. Maps of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were used to assess developmental changes. Because directionally encoded color (DEC) maps provide an efficient and straightforward way to visualize anisotropy direction, they were used to highlight the orientation-dominant anisotropic tissues. In the corpus callosum, the increases in FA (approximately 0.4 to approximately 0.6 from P15 to P45) were primarily dominant in the medial-lateral direction, whereas the ADC decreased slightly (approximately 0.8 x 10(-3) to approximately 0.5 x 10(-3) mm(2)/s from P15 to P45). Similar increases in FA (approximately 0.3 to approximately 0.4 from P15 to P45) and decreases in ADC (approximately 0.8 x 10(-3) to approximately 0.5 x 10(-3) mm(2)/s from P15 to P45) were found in the cingulate, but these anisotropic changes were dominant in the anterior-posterior direction. In the caudate putamen, there were significant FA increases (approximately 0.1 to approximately 0.2 from P15 to P45) dominant in the dorsal-ventral and anterior-posterior directions, whereas the ADC increased rapidly early in development (approximately 0.3 x 10(-3) to approximately 0.7 x 10(-3) mm(2)/s from P15 to P17). There were no significant changes in tissue anisotropy in the somatosensory regions (whisker, forelimb), but the ADC decreased slightly (approximately 0.7 x 10(-3) to approximately 0.5 x 10(-3) mm(2)/s from P15 to P45). Although the major differences in DEC values were mainly observed in white matter pathways, other cortical and subcortical regions showed some potential morphological changes that were consistent with classical histological findings. In summary, these results show that high-resolution DTI at high magnetic fields allows detection and quantification of brain structures throughout normal development in C57B/L6 mice in vivo.

Sexual dimorphism of brain developmental trajectories during childhood and adolescence

Human total brain size is consistently reported to be approximately 8-10% larger in males, although consensus on regionally specific differences is weak. Here, in the largest longitudinal pediatric neuroimaging study reported to date (829 scans from 387 subjects, ages 3 to 27 years), we demonstrate the importance of examining size-by-age trajectories of brain development rather than group averages across broad age ranges when assessing sexual dimorphism. Using magnetic resonance imaging (MRI) we found robust male/female differences in the shapes of trajectories with total cerebral volume peaking at age 10.5 in females and 14.5 in males. White matter increases throughout this 24-year period with males having a steeper rate of increase during adolescence. Both cortical and subcortical gray matter trajectories follow an inverted U shaped path with peak sizes 1 to 2 years earlier in females. These sexually dimorphic trajectories confirm the importance of longitudinal data in studies of brain development and underline the need to consider sex matching in studies of brain development.

Neurogenesis in the caudate nucleus of the adult rabbit

Stem cells with the potential to give rise to new neurons reside in different regions of the adult rodents CNS, but in vivo only the hippocampal dentate gyrus and the subventricular zone-olfactory bulb system are neurogenic under physiological condition. Comparative analyses have shown that vast species differences exist in the way the mammalian brain is organized and in its neurogenic capacity. Accordingly, we have demonstrated recently that, in the adult rabbit brain, striking structural plasticity persists in several cortical and subcortical areas. Here, by using markers for immature and mature neuronal and glial cell types, endogenous and exogenously administered cell-proliferation markers, intraventricular cell tracer injections coupled to confocal analysis, three-dimensional reconstructions, and in vitro tissue cultures, we demonstrate the existence of newly formed neurons in the caudate nucleus of normal, untreated, adult rabbit. Our results suggest that neurogenesis in the caudate nucleus is a phenomenon independent from that occurring in the adjacent subventricular zone, mostly attributable to the activity of clusters of proliferating cells located within the parenchyma of this nucleus. These clusters originate chains of neuroblasts that ultimately differentiate into mature neurons, which represent only a small percentage of the total neuronal precursors. These results indicate that striatum of rabbit represents a favorable environment for genesis rather than survival of newly formed neurons.

MR quantitation of volume and diffusion changes in the developing brain

BACKGROUND AND PURPOSE

Brain volume and diffusion change during maturation. Quantitation of these changes may be helpful in understanding normal brain development. We used diffusion-weighted imaging to characterize the volumetric and diffusion changes in vivo.

METHODS

We recruited 30 pediatric volunteers (aged 1 month-17 years; 14 male, 16 female). Diffusion was measured in three orthogonal directions with a b value of 1000 s/mm2. The diffusion parameters from the entire brain were calculated and fitted to a triple gaussian model. In addition, region-of-interest measurements were made in caudate, thalamus, genu and splenium of the corpus callosum, and periventricular white matter (PVWM). The brain volume was measured by counting pixels and by using the model.

RESULTS

Water diffusion of the whole brain, caudate, thalamus, genu and splenium of the corpus callosum, and PVWM decreased during maturation, with the most significant change within the first 2 years. Robust negative correlations were found between age and the measured average diffusion constant (Dav) values in each of the measured locations (P <.005). Volumes of different cerebral compartments and the total intracranial volume (ICV) increased rapidly during the first 2 years of life and then had a slower growth process through adolescence. Age was correlated with the ICV and the volume of each brain compartment (P <.005).

CONCLUSION

Brain diffusion decreases and brain volume increases during maturation, with the most significant changes occurring within the first 2 years of life. The brain model used in this study provides a good estimate of the increasing brain volume.

Early development of subcortical regions involved in non-cued attention switching

This study examined the cognitive and neural development of attention switching using a simple forced-choice attention task and functional magnetic resonance imaging Fourteen children and adults made discriminations among stimuli based on either shape or color. Performance on these trials was compared to performance during blocked trials requiring all color or all shape discriminations. Magnetic resonance echo planar images were acquired during performance of the task. Both children and adults showed robust bilateral activity of the caudate nucleus when switching attention between color and shape discriminations that correlated negatively with mean response latency on these trials. However, neither switching costs nor caudate activity correlated with age, suggesting early development of the underlying neural circuitry involved in switching between salient stimulus sets. Overall, children and adults differed in performance and patterns of brain activity on the task, with adults responding more accurately and faster than children, and recruiting more prefrontal and parietal regions. These results suggest an important role of subcortical regions (i.e. caudate nucleus) in non-cued attention switching, with increasing recruitment of cortical regions with age.

Activity-regulated cytoskeleton-associated protein Arc is targeted to dendrites and coexpressed with mu-opioid receptors in postnatal rat caudate-putamen nucleus

Dendritic expression of the activity-regulated cytoskeleton-associated protein (Arc) is dramatically enhanced by increased synaptic activity in adult brain. We used immunocytochemical electron microscopy to determine whether the subcellular localization of Arc in developing dendrites corresponds to the peak period of synaptogenesis in the postnatal rat caudate-putamen nucleus (CPN). The distribution was compared with that of mu-opioid receptors (MORs), whose localization in dendritic spines closely parallels excitatory synapse formation during postnatal development (Wang et al. [2003] Neuroscience 118:695-708). Sections were processed for immunocytochemical detection of antisera against Arc or MORs at the beginning (postnatal day 15; P15) and the end (P30) of the peak period of synaptogenesis in rat CPN. At P15, immunolabeling for Arc showed a punctate distribution in the cytoplasm of dendritic shafts, some of which was associated with polyribosomes. In some spiny dendrites, Arc immunoreactivity was more intensely localized in putative spines than in their parental dendrites, whereas, in other spiny dendrites, Arc labeling was restricted in the shafts. Many dendritic shafts and spines also showed immunoreactivity for MORs, although dually labeled spines were less numerous than the shafts. At P30, the proportion of singly and dually labeled spines significantly increased from 2.0% to 7.5% and from 9.5% to 21%, respectively. Arc labeling in spines was more detectable beneath the postsynaptic density or at extrasynaptic sites on the plasma membrane. Our results suggest a correlation between Arc expression in dendritic spines during postnatal development and the onset of synaptogenesis in opioid-responsive neurons in the rat CPN.

Differentiation of the midbrain dopaminergic pathways during mouse development

Dopaminergic (DA) neurons in the substantia nigra (SN) and ventral tegmental area (VTA) of the midbrain project to the dorsolateral caudate/putamen and to the ventromedially located nucleus accumbens, respectively, establishing the mesostriatal and the mesolimbic pathways. Disruptions in this system have been implicated in Parkinson's disease, drug addiction, schizophrenia, and attention deficit hyperactivity disorder. However, progress in our understanding has been hindered by a lack of knowledge of how these pathways develop. In this study, different retrograde tracers, placed into the dorsolateral caudate/putamen and the nucleus accumbens, were used to analyze the development of the dopaminergic pathways. In embryonic day 15 mouse embryos, both SN and VTA neurons, as well as their fibers, were doubly labeled by striatal injections into the dorsolateral and ventromedial striatum. However, by birth, the SN DA neurons were labeled exclusively by DiA placed in the dorsolateral striatum, and the VTA DA neurons were labeled only by DiI injected into the ventromedial striatum. These data suggest that initial projections from midbrain DA neurons target nonspecifically to both the dorsolateral striatum and the nucleus accumbens. Later during development, the separate mesostriatal and mesolimbic pathways differentiate through the selective elimination of mistargeted collaterals.

17beta-Estradiol promotes striatal medium size spiny neuronal maturation in vitro

Gender differences exist in the development of the nigrostriatal dopamine system, and in the incidence and course of pediatric and adult neuropsychiatric diseases in which this system is implicated. The medium size spiny neuron (MSN) is the major output neuron of the caudate nucleus. It receives a large dopaminergic input from the substantia nigra, and 96% of the MSNs express DARPP-32, a dopamine and cyclic AMP-regulated phosphoprotein and key mediator of dopamine function. There are few examples, however, of direct effects of sex hormones, including 17beta-estradiol (E(2)), on the MSN. We report that in vitro, E(2) (10-50 nM) promotes MSN phenotypic maturation, as determined by increased soma size, neurite length, and DARPP-32 protein levels. Treatment with the 'anti-estrogen' ICI 182,780 or the partial-agonist tamoxifen also increases DARPP-32 levels, but when added to E(2), ICI 182,780 only prevents the increase in DARPP-32 levels and increase in soma size and neurite length. Surprisingly, maturation effects are more robust in cells derived exclusively from female embryos. Western blot analysis of protein lysates and immunocytochemistry of cultured MSNs reveals the presence of the estrogen receptor beta (ERbeta). These data suggest that ERbeta may mediate the differentiating effect of E(2) on embryonic MSNs, and provide new avenues of investigation for the role of sex hormones in the development of the striatum and in diseases affecting the basal ganglia.

Ultrastructural localization of ?-opioid receptors in the rat caudate-putamen nucleus during postnatal development: Relation to synaptogenesis

During development, delta-opioid receptors (DORs) in the rat caudate-putamen nucleus (CPN) appear later than mu-opioid receptors (MORs), whose developmental pattern specifically relates to synaptogenesis. We used electron microscopic immunocytochemistry to determine whether there are also age-related changes in subcellular localization of DORs in the rat CPN. Sections from postnatal day (P) 0-P30 and adult dorsomedial CPN were immunogold-silver labeled to examine the plasmalemmal and cytoplasmic distribution of these receptors. In addition, immunoperoxidase labeling was used to determine the numerical density of synapses relative to DOR-labeled profiles. Immunolabeling for DOR was undetectable at P0, light at P5, and dense from P10 onward. The labeling during P5-P10 was mainly localized in somatodendritic profiles but also was readily seen in axon terminals, most of which formed asymmetric synapses with dendrites. From P15, a few immunogold particles were seen in contact with postsynaptic densities in spines, and the proportion of these particles significantly increased in P30 and adult CPN. Other particles were localized in the cytoplasm of dendrites and terminals without significant age-related changes. Stereological analysis showed that compared with labeled dendritic shafts and spines, labeled axon terminals have a closer correlation with synapse formation. These results are in marked contrast with MORs, which show an age-related increase in association with dendritic plasma membrane and a good correlation in the developmental pattern of MOR-labeled spines with synapse formation (Wang et al. [2003] Neuroscience 118:695-708). Together, our results suggest receptor-type specific roles for endogenous opioids acting at both pre- and postsynaptic sides in the developing CPN.

Postnatal development of mu-opioid receptors in the rat caudate-putamen nucleus parallels asymmetric synapse formation

The mu-opioid receptor (MOR) in the caudate-putamen nucleus (CPN) appears early during prenatal development, and shows a patch-like distribution throughout the postnatal period and adulthood. In the adult rat CPN, neurons in patch compartments receive glutamatergic excitatory input mainly from the cortex through synapses onto spines, many of which express MORs. Thus, MOR expression in spines may be related to corticostriatal synaptogenesis. We used electron microscopic immunocytochemistry to determine potential age-dependent changes in the distribution pattern of MOR during postnatal synaptogenesis in the rat CPN. Immunogold-silver labeling revealed that the dendritic plasmalemmal density of MOR at postnatal day (P) 0 was significantly lower than, but after P10 was similar to, that of adult. In contrast, such age-dependent changes were not observed in axon terminals. Stereological analysis of immunoperoxidase labeling for MOR showed a good correlation in the developmental numerical densities of synapses with MOR-labeled spines and those of total asymmetric axospinous synapses, linear correlation coefficient r=0.99. Synapses with MOR-labeled dendrites, however, had a low correlation with axodendritic synapses (r=0.61), and synapses with MOR-labeled terminals showed no correlation with axospinous and axodendritic synapses (r=0.19). These results provide ultrastructural evidence that the targeting of MOR on the plasma membrane of dendrites and spines parallels the peak period of synaptogenesis during the third postnatal week in the rat CPN. Thus, the postnatal spatiotemporal expression pattern of MOR appears to match the functional maturation of corticostriatal glutamate transmission.

Age-related changes in the N-methyl-D-aspartate receptor binding sites within the human basal ganglia

The present study examined the regional differences in dopamine transporter binding sites and NMDA receptor complex binding based on autoradiographic images obtained in postmortem sections of human normal brain tissues. In middle-aged control tissues, high and comparable levels of [(3)H]CFT binding were observed in the caudate nucleus, putamen, and accumbens nucleus without significant alteration along the rostrocaudal axis and ventral and dorsal parts of these nuclei. In aging normal brain tissues, dopamine binding sites for [(3)H]CFT were significantly reduced in the caudate nucleus, putamen, and accumbens nucleus. l-[(3)H]Glutamate, [(3)H]MK-801, and [(3)H]glycine binding to the NMDA receptor complex was lower in aging brain tissues than in middle-aged controls. Significant correlation did occur between age and [(3)H]CFT binding and between age and l-[(3)H]glutamate, [(3)H]MK-801, and [(3)H]glycine binding sites. These results demonstrate that the basal ganglia have age-associated reductions in dopamine transporter uptake and NMDA receptors. These data support hypoactive activity of the NMDA receptor complex system with advancing age. The dopamine transporter uptake and NMDA receptors appear to be vulnerable to the aging process in the basal ganglia.

Catecholamines inhibit lipid peroxidation in young, aged, and Alzheimer's disease brain

Some catecholamines and indolamines inhibit lipid peroxidation. Recent studies indicate that catecholaminergic inhibition of lipid peroxidation may be receptor mediated in vivo and in cell cultures. Because oxidative stress is one of the hypothesized pathogenic mechanisms for neurodegenerative diseases, including Alzheimer's disease (AD), we hypothesized that catecholaminergic and indolaminergic inhibition of lipid peroxidation would be altered in AD as compared to age-matched non-AD. To test this hypothesis we studied the effect of a variety of neurotransmitters and their antagonists on ascorbate-stimulated lipid peroxidation in membrane fragment preparations derived from postmortem human brain. In this in vitro system, the inhibition of lipid peroxidation by dopamine and serotonin did not appear to be receptor mediated. Further, our findings indicate that there is no apparent effect of age or AD on the inhibition of lipid peroxidation by catecholaminergic and indolaminergic agents.

The growth of the feline brain from fetal into adult life. II. A morphometric study of subcortical nuclei

As a continuation of the morphometric studies on the preceding paper, here we report on the rate of growth of the caudate nucleus (n.), thalamus, red n., and the substantia (s.) nigra using, with few exceptions, the same cohort of cats. The same previously used brains (n=64 cats) were allocated to the following age groups: fetal (E) 59 days, postnatal (P) days 1, 7, 15, 30, 45, 60, 90, 120, and 180. Sixteen additional cats, interspersed within the groups, were substituted for the red n. and s. nigra studies. There were six subjects per group (except for E59, n=4). Using a projection microscope and cytochrome oxidase-stained coronal sections, a combined (left plus right sides) total of 4693, 3822, 1636, and 1180 sections were drawn for the caudate, thalamus, s. nigra, and red n., respectively. With computer assistance, the drawings were digitized to calculate mean cross-sectional areas and then the mean volume of each structure per group. The growth time tables for the caudate n., thalamus and s. nigra were fairly synchronous. In terms of percentage of the adult volume, for the left side (both sides grew at a similar rate), the three structures grew at a fast pace between E59 and P30. Thus, at E59 their respective percentages relative to adult volume were 23.7, 29.8 and 22.6% and by P30 the percentages were within adult range (85.2, 115.1 and 87.5%, respectively). Starting at P30, for the thalamus and at P45 for the caudate n., there was a consistent tendency to an overgrow which ranged between 4.3 and 30.9% (at P180, P<0.5) for the caudate and between 0.3 and 15.1% for the thalamus. In addition, starting at P30, the right thalamus tended to be consistently larger than the left by a margin ranging between 0.5 and 11.2% (P120, P<0.05). The red n. grew at a different, slower pace. Starting from a fetal volume equivalent to an 18.6% of adult size, its volume was only a 61.0% of the adult value at P30 and came within range of adulthood size only by P60 (81. 3%). Neither the s. nigra nor the red n. showed any consistent tendency to overgrow or to asymmetry. These findings are discussed in the context of the literature. Furthermore, we discuss general conclusions and considerations pertaining to both papers as well as draw comparisons with the maturational time tables of other developmental landmarks in cats. Finally, in a comparison with growth of human brain structures, we point at the limitations and complexities involved in studying human material and, noting interspecies similarities, we propose that the present data from an advanced gyrencephalic mammal may form the bases for a model of structures maturation in humans.

Developmentally regulated expression of Thy-1 in structures of the mouse sensory-motor system

Thy-1 is a cell-surface molecule of the immunoglobulin superfamily which is expressed at high levels in the mature nervous system. Thy-1 has been implicated in regulating axonal outgrowth and synaptic function, but little is known regarding its cellular localization and expression in the central nervous system (CNS) during development or in adulthood. In this study, Thy-1 gene expression and protein localization were examined in sensory-motor and related areas of the adult and postnatally developing mouse CNS. Thy-1 mRNA expression was restricted to neurons; immunoreactivity was densely distributed throughout the neuropil of all regions examined, often delineated the neuronal plasmalemma, and labeled axons in white matter tracts of the brain and spinal cord. In adulthood, immunolabeling was regionally widespread and was present relatively homogeneously throughout all cell-dense layers of sensory-motor cortex, throughout most thalamic nuclei, globus pallidus, and spinal cord. Developmentally, however, Thy-1 expression and localization exhibited a spatially and temporally staggered sequence leading to the adult pattern. In sensory-motor cortex, Thy-1 expression in layer V preceded expression in other layers; in the barrel field, labeling of barrel septa preceeded a gradually increasing intensity of immunolabeling of barrel centers; in the thalamus, Thy-1 exhibited a differential onset and temporal pattern of expression across different nuclei associated with motor, sensory, or limbic systems; in the caudate nucleus, Thy-1 expression was greatest during the first postnatal week of life before declining during subsequent development. Taken together, the adult distribution and developmental patterns leading to it form a unique profile in comparison with other structurally related glycosyl-phosphatidylinositol (GPI)-anchored neural cell adhesion molecules. The pattern and timing of Thy-1 expression across layers and nuclei during early postnatal development are more complex than previously recognized, thus perhaps reflecting varied roles for Thy-1 in aspects of structural or functional maturation which proceed independently of the timing of neurogenesis, migration, and dendritic and axonal growth.

Developmental regulation of the dopamine D1 receptor in human caudate and putamen

Perturbations in the developmental regulation of the dopaminergic system have been hypothesized to participate in the age-dependent onset of schizophrenia. Although data from studies of non-human primates suggest that dopamine D1-like receptors decrease during adolescence, less information is available concerning changes in human brain. The present study employed quantitative receptor autoradiography to measure D1-like receptor density and affinity in human caudate and putamen. Samples were obtained postmortem from 15 subjects (9 weeks to 49 years), and grouped a priori into three classes: infants, adolescents, and adults. Receptor density and affinity were assessed by saturation binding with [3H]-SCH23390, a D1 receptor antagonist. A decrease in D1 receptor density was observed from infancy to adulthood, with no change in receptor affinity. The temporal pattern of D1-like receptor expression during maturation may play a role in the interaction of dopamine with other neurotransmitter systems, and in the occurrence and pharmacotherapy of neurological and neuropsychiatric disorders.

D2 receptor binding in dopa-responsive dystonia

We have studied dopamine D2 receptor binding by [11C]raclopride positron emission tomography in 14 patients with dopa-responsive dystonia (DRD). Data were compared with 16 levodopa-treated patients with Parkinson's disease (PD) and 26 healthy controls. The results revealed an elevated [11C]raclopride binding index in the putamen and caudate nucleus of DRD patients compared with controls as well as a significant elevation in the caudate nucleus compared with PD patients. The increase of [11C]raclopride binding may be interpreted either as reduced tracer displacement by endogenous dopamine, or as an alteration of the receptor features due to chronic dopamine deficiency. The difference in [11C]raclopride binding in DRD and PD patients in the caudate nucleus suggests that this structure may be of pathophysiological relevance in the presentation of the clinical features of both diseases.

Postnatal development of dopamine and serotonin transporters in rat caudate-putamen and nucleus accumbens septi

Density of dopamine transporter (DAT) and serotonin transporter (5-HTT) membrane proteins in the caudate-putamen (CPu) and nucleus accumbens (NAc) of rat brain was assessed at seven ages at postnatal days (PD) 7-60, by in vitro quantitative autoradiography. Binding of [3H]GBR-12935 (to DAT) and [3H]paroxetine (to 5-HTT) increased steadily and very similarly, from low levels at PD-7 to maximal levels, to 6-7-fold higher density at PD-60 in both regions. These findings indicate that DAT and 5-HTT follow a synchronized course of development in rat CPu and NAc. In contrast to reported elimination of excessive receptors in CPu and NAc during maturation, there was no evidence of pruning of DAT or 5-HTT in these regions of rat forebrain.

Mouse brain potassium channel beta1 subunit mRNA: cloning and distribution during development

The pore-forming alpha subunits of voltage-gated potassium channels in neurons and other excitable cells are expressed in association with accessory beta subunits. These subunits both promote insertion of channel complexes into surface membranes and influence their electrophysiological properties. As part of an effort to understand the regulation of voltage-gated potassium channels during development, we cloned the mouse homolog of the rat Kvbeta1 potassium channel subunit. Kvbeta1 subunits are known to associate preferentially with Shaker (Kv1)-related alpha subunits. We then used a digoxigenin-tagged cRNA probe and in situ hybridization techniques to visualize the appearance of Kvbeta1 mRNA transcripts during late embryonic and early neonatal development of the mouse brain. We detected Kvbeta1-specific labeling of cells in hippocampus, cerebral cortex, caudate putamen, colliculus, and cerebellum. In hippocampus, we observed Kvbeta1 mRNA in CA3 pyramidal neurons at the earliest time examined, embryonic day 16 (E16). Between E16 and postnatal day 7 (P7), cell labeling increased uniformly across the pyramidal neurons of Ammon's horn (CA1, CA2, and CA3). Subsequently, between P7 and P22, regional differences characteristic of mature hippocampus appeared-intense labeling of neurons in CA3 and CA1, and less in CA2. In cortex, labeling of cells in the subplate and cortical plate layers was observed at E16. During development, the intensity of this labeling increased, and labeled cells persisted into the adult stage in the deep cortical layer (VIb) formed from subplate neurons. Additional labeling of scattered solitary cells in cortical layers II-VIa emerged between P3 and P7 and was prominent in mature cortex. In caudate putamen, Kvbeta1-labeled cells were observed at P1 and were restricted to the lateral and rostral half of the caudate. During development, labeling expanded caudally and medially and eventually filled the mature caudate putamen. In colliculus, a small population of inferior colliculus cells showed labeling at P7, and additional labeling of scattered cells appeared during development. In superior colliculus, labeling was observed only in the adult deep gray layer. In cerebellum, intense labeling was observed in Purkinje cells at all stages between P1 and adult. Labeling was also seen in granule neurons in the external granule layer at early postnatal stages and in the inner granule layer beginning at P7.

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.

[Vascular architecture of the caudate nucleus]

The aim of this study is to describe the vascular characteristics of the nucleus caudatus (NC). This study is performed on 30 human brains by injecting the vascular system with gelatinous Indian ink. Examination of serial slices, 250 microns thickness, made translucent by the Spalteholz method, enabled us to follow the course and behavior of the vessels of the NC. The arteries of the NC belong to the group of the central arteries arising from the anterior and middle cerebral arteries or from the anterior choroidal arteries. Inside the different parts of the NC (head, body and tail) the central arteries and their ramifications give rise to a specific vascular network quite similar to this one of the putamen. This network consists of regular, polygonal, rectangular or square meshes. Each mesh is composed by the juxtaposition of vascular units formed by an arterial ring arranged around a principal vein which is surrounded by a capillary free space. The arterioles of the network of the NC are terminal or side branches of the central arteries. They are characteristic in their course by forming rope-like structures (coils) also described on the ramifications of the putaminal central arteries. Similarities between the vascular networks of the NC and the putamen are in relation with the histological structure, with the morphogenetic evolution, with the functional activity. The specificity and the clear delimitation of the vascular networks of the NC and of the putamen are particularly obvious in cerebral vascular diseases leading to infarcts strictly limited to these two nuclei.

Nitric oxide-mediated cGMP synthesis in oligodendrocytes in the developing rat brain

We investigated the nature of cGMP-synthesizing cells in the developing rat forebrain using cGMP-immunocytochemistry in combination with in vitro incubation of brain slices. When brain slices of immature rats, aged between 1 and 4 weeks, were incubated with sodium nitroprusside (SNP), a nitric oxide (NO) donor compound, in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine (IBMX), small round cells with a few processes in and around the corpus callosum were visualized with the cGMP-antibody. The morphology and the distribution of the cGMP-positive cells were consistent with the criteria for oligodendrocytes. Furthermore, the cGMP-positive cells expressed 2'3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and gelsolin, which are marker proteins for oligodendrocytes. Therefore, we concluded that the cGMP-positive cells were oligodendrocytes. A subpopulation of the oligodendrocyte was found to be cGMP-immunoreactive also when slices were incubated in the absence of SNP. Furthermore, incubation of the slice in the presence of L-NAME, an inhibitor of NO synthase, but in the absence of SNP abolished cGMP immunostaining. In addition, some populations of neurons and astrocytes in restricted brain areas produced cGMP in response to the incubation with SNP as previously reported, whereas both ameboid and ramified microglial cells did not respond to the treatment. Atrial natriuretic peptide, a stimulator of particulate guanylyl cyclase, enhanced cGMP synthesis in astrocytes in some brain regions but not in oligodendrocytes. These findings indicate that oligodendrocytes in the immature rat brain express soluble guanylyl cyclase. No cGMP-positive oligodendrocytes were found in the mature rat brain, suggesting that cGMP may mediate signals related to myelinogenesis in the rat brain.

Reduction in number of dopamine uptake sites but unchanged number of piperazine-acceptor/CYP450IID6 binding sites in the human caudate nucleus in aging

A substantial decrease in number of striatal dopamine uptake sites is a characteristic finding in aging. This decrease resembles the dopaminergic nigro-striatal degeneration in Parkinson's disease (PD). A dysfunction of cytochrome P450IID6 (debrisoquine-4-hydroxylase) is suggested to be involved in the pathogenesis of PD. In this study, binding sites associated with the neuronal form of P450IID6 were studied in the caudate nucleus from individuals in the age range 20-81 years using [3H]GBR 12935 as a radioligand. No significant changes in binding parameters were obtained, while in the same region a significant decrease in number of dopamine uptake sites occurred. Thus, in aging, P450IID6 and dopaminergic degeneration seem not to be functionally related in this region. Whether such a relation exists in PD is still to be examined.

Right-left asymmetry of D1- and D2-receptor density is lost in the basal ganglia of old rats

In the present study a left-right asymmetry in both D1- and D2-receptor density in the caudate-putamen nucleus is shown and a lateralisation of D2-receptor distribution in the accunbens nucleus is also described. In old animals in which D1- and D2-receptors density is decreased, the dopamine receptor asymmetries are lost.

Neurophysiological, pharmacological and morphological properties of human caudate neurons recorded in vitro

Tissue samples from the caudate nucleus were obtained from eight children (eight to 172 months of age) who underwent hemispherectomies for the relief of intractable seizures. Neurophysiological, pharmacological and morphological properties of caudate neurons were characterized by intracellular recordings in an in vitro slice preparation. These properties were compared with those of tissue obtained from animal studies. Electrophysiological properties of human caudate neurons that were similar to those of cat caudate and rat neostriatal cells included resting membrane potential, input resistance, action potential rise time, fall time, duration and action potential afterhyperpolarization amplitude, as well as the general characteristics of locally evoked synaptic responses. Properties that were different included action potential amplitudes and time-constants. Human caudate neurons also displayed responses similar to those of cat caudate or rat neostriatal cells to manipulation of excitatory amino acid receptor systems and to dopamine application. Kynurenic acid, a broad-spectrum excitatory amino acid receptor antagonist, decreased the amplitude of evoked synaptic responses, indicating that they were partially mediated by excitatory amino acids. In Mg2+ free Ringer's solution, the amplitudes and durations of postsynaptic responses were increased and bursts of action potentials were induced. These effects were mediated by activation of N-methyl-D-aspartate receptors since they were blocked by 2-amino-5-phosphonovalerate, a specific N-methyl-D-aspartate-receptor antagonist. Iontophoretic application of N-methyl-D-aspartate also induced membrane oscillations and bursts in almost all caudate neurons. Dopamine decreased the amplitude of postsynaptic responses, an effect antagonized by domperidone, a selective D2 dopamine receptor antagonist. Developmentally, the greatest change was an increase in action potential amplitude, although input resistance decreased and action potential afterhyperpolarization amplitude increased. Postsynaptic responses were similar across age. All but one of the caudate neurons identified by intracellular injection of biocytin or Lucifer Yellow were medium-sized spiny cells. These experiments show that human caudate neurons display a number of electrophysiological properties similar to rat neostriatal or cat caudate neurons recorded in brain slices. Furthermore, few electrophysiological parameters changed significantly over the age period examined suggesting that the human caudate at eight months displays many of the neuronal functions of the more mature caudate nucleus.

Cerebral hemidecortication alters expression of transforming growth factor alpha mRNA in the neostriatum of developing rats

Transforming growth factor alpha (TGF alpha) is a mitogenic polypeptide which acts at the epidermal growth factor receptor to produce its biologic effects. Recent studies have demonstrated that TGF alpha may act as a neurotrophic factor. Cerebral hemispherectomy (hemidecortication) is performed on some children with intractable epilepsy. Prior studies have demonstrated improved functional recovery in both children and animals when the surgery is performed at a very early age. In order to test whether TGF alpha may be involved in the functional recovery of the neostriatum following cerebral hemidecortication, we performed in situ hybridization for TGF alpha mRNA on brains of rats which underwent hemispherectomy at postnatal day (P) 6 or P12 or in adulthood, and sacrificed one, 7, or 30 days following surgery. Normal striatal expression in control animals was very high at P6 and then decreased throughout development. In animals undergoing lesion at earlier ages (P6 and P12), TGF alpha mRNA expression was first depressed in the ipsilateral neostriatum one day after surgery and then elevated to supranormal levels 7 and 30 days after surgery. Maximal decreases (40% below contralateral neostriatum) were seen in animals lesioned at P12 and sacrificed the next day. Maximal elevations (60% greater than opposite neostriatum) were seen in animals operated on at P6 and sacrificed 30 days post surgery. Expression in the adult animal was only mildly affected, with a 20% increase found in the ipsilateral caudate 7 days after the lesion, but no significant changes after one or 30 days survival.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Increase in size of the caudate nucleus of the cat after a prenatal neocortical lesion

In order to study the influence of prenatal developmental factors upon reaction of the brain to injury, fetal kittens (E43-48) were lesioned in the frontal or parietal cortex unilaterally and maintained into young adulthood. The animals were sacrificed by perfusion with an aldehyde fixative or by an overdose of pentobarbital. Frozen sections were cut and stained with thionin. These sections were used for calculation of caudate nuclei volumes and for measurements of neuronal and glial cell packing density and neuronal cell body size. Island and matrix compartments were sampled separately. We found that the volume of the ipsilateral caudate nucleus had significantly increased as compared to (a) the volume of the corresponding nucleus in intact cats (mean, 15%) and (b) the nucleus contralateral to the lesion (mean, 7.6%). The latter nucleus also tended to a volume increase (mean, 8.1%). The cytoarchitecture of the caudate nuclei was essentially unchanged with two exceptions. The neuronal cell packing density in the matrix compartment of the contralateral side was decreased (mean, 14.9%) while the size of neuronal cell bodies in the island compartment of the nucleus ipsilateral to the lesion was smaller (mean, 5%) relative to controls. These findings suggest that the number of neurons in the caudate of lesioned animals was larger than in intact controls, particularly on the lesioned side of the brain. This might be due to a reduction of naturally occurring cell death during development.

Developmental regulation of phosphoprotein gene expression in the caudate-putamen of rat: an in situ hybridization study

The regional and cellular ontogeny of the mRNA encoding the dopamine- and cAMP-regulated phosphoprotein, DARPP-32, has been studied in rat striatum by quantitative in situ hybridization histochemistry. The mRNA for DARPP-32 exhibited a characteristic developmental profile. The hybridization signal was first visible on the day of birth, at which time DARPP-32 mRNA was concentrated in patches in the caudate-putamen. By the end of the first postnatal week, the majority of neurons in the caudate-putamen expressed the DARPP-32 message. Levels of mRNA per cell increased markedly during the second postnatal week, and peaked around the beginning of the third week. The adult level of DARPP-32 mRNA was lower than that observed at the apex of mRNA expression, on a per cell basis, while the proportion of neurons expressing detectable levels of message remained relatively constant. In the nucleus accumbens and olfactory tubercle, DARPP-32 mRNA development lagged somewhat behind that observed in the caudate-putamen, but was similar in other respects. A non-quantitative study employing an oligonucleotide probe complementary to the mRNA encoding another cAMP-regulated phosphoprotein, ARPP-21, revealed a similar developmental sequence to DARPP-32. The present results suggest that for DARPP-32 mRNA, genetic and, possibly, environmental factors play a role in determining the developmental patterns observed.

Age-related anticonvulsant activity of NMDA in the rat caudate-putamen

Striatal pathways are important for modulating the threshold for seizures in the rat forebrain. N-Methyl-D-aspartate (NMDA), an excitatory amino acid derivative and powerful anticonvulsant agent, when injected into the brain, has been shown to protect adult rats against kindling and pilocarpine-induced seizures when injected into the caudate-putamen. The present study examines whether the anticonvulsant action of NMDA in the caudate-putamen varies with age. Bilateral striatal administration of NMDA was effective in suppressing bicuculline-induced seizures in rats older than 23 days of age. The results suggest that striatal pathways involved in the anticonvulsant activity of NMDA in the caudate-putamen are not functionally active in developing rats before the 4th week of life.

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.

Afferent-boundary interactions in the developing neostriatal mosaic

The caudate-putamen (neostriatum) of the mammalian basal ganglia is composed of two neurochemically distinct compartments termed patch (island, striosome) and matrix that overall contribute to a mosaic organization. In the present study, the distribution of the developmentally regulated extracellular matrix molecule tenascin, as well as several other neural cell adhesion molecules, was examined in the neostriatal mosaic of the early postnatal mouse and compared with tyrosine hydroxylase distribution following partial destruction of the dopaminergic nigrostriatal projection. During normal neostriatal development, tenascin is most dense within the matrix compartment and highly concentrated in boundaries around patches. This pattern is apparent on embryonic day 18, and for the most part disappears by postnatal day 12. Tenascin immunoreactivity is altered in the neostriatum following lesions of the nigrostriatal pathway in the first postnatal week revealed by an overall reduced expression of this molecule and a marked reduction in tenascin staining of boundaries at the interface of tyrosine hydroxylase-rich patch and tyrosine hydroxylase-poor matrix compartments. When compared to tyrosine hydroxylase immunoreactivity, other cell adhesion molecules tested failed to show altered intensities and patterns of immunoreactivity within the neostriatum after similar lesions. Reduced levels of tenascin in the lesioned neostriatum, in register with altered levels of tyrosine hydroxylase immunostaining of dopaminergic inputs, suggests that axons may affect the expression of particular recognition molecules in their target structures. The fact that boundaries are malleable can be related to afferent-induced plastic events in the differentiation of cellular elements in the developing nigrostriatal system.

Differential ontogenetic expression and regulation of proenkephalin and preprosomatostatin mRNAs in rat caudate-putamen as studied by in situ hybridization histochemistry

Specific oligonucleotide probes and in situ hybridization histochemistry were used to study the ontogeny and regulation of the mRNAs for proenkephalin A and preprosomatostatin in rat brain. In adult brain the most intense hybridization signal for the proenkephalin A mRNA was in caudate putamen, nucleus accumbens and olfactory tubercle. By contrast, the hybridization signal for preprosomatostatin mRNA was more diffusely scattered throughout the brain, with high signals in the neocortex, olfactory bulb and hippocampal formation. Studies of the ontogeny of these mRNAs revealed a different pattern of ontogenetic expression and differential regulation by dopaminergic input. The mRNA for preposomatostatin reached the highest level within the first postnatal week, whereas proenkephalin A mRNA progressively increased throughout the entire period studied. In addition the proenkephalin A mRNA showed a medial to lateral gradient in 2-day-old rat striatum which disappeared with increasing age, whereas preprosomatostatin mRNA increased in most brain areas in fairly uniform fashion with increasing age. Treatment of newborn rats with 6-hydroxydopamine increased the expression of proenkephalin A mRNA by 1.6 fold but had no effect on the expression of preprosomatostatin mRNA. The 6-hydroxydopamine-induced change in proenkephalin A mRNA expression was not observed until postnatal day 32, indicating that enkephalin-containing neurons of the developing striatum are relatively insensitive to dopamine input and that they cannot compensate for the neonatal lesion, despite the fact that the insult was given in a period of high plasticity of the neural tissue.

Iontophoretic application of NMDA produces different types of excitatory responses in developing human cortical and caudate neurons

The effects of iontophoretically applied N-methyl-D-aspartate (NMDA) were assessed in human neocortical and caudate neurons. NMDA depolarized cell membranes, decreased input conductances and induced firing. The discharge patterns differed in the two areas studied. In neocortex, NMDA produced repetitive spikes or bursts. In caudate, it induced slow, rhythmic plateau depolarizations accompanied by an initial burst of action potentials, followed by low amplitude, long duration spikes. After hyperpolarizations were seen after each depolarization in the caudate. These variations in patterns of excitation may relate to differences in local circuits intrinsic to each region, and/or to membrane conductances specific to each type of cell.

Neurophysiological maturation of cat caudate neurons: evidence from in vitro studies

The membrane properties and synaptic physiology of developing cat caudate (Cd) nucleus neurons were studied in in vitro slice preparations. Recordings were obtained from 98 cells in kittens from fetal day (F) 56 to postnatal day (P) 90. With increasing age, the following maturational changes occurred; resting membrane potentials became more negative, action potential rise times decreased, action potential amplitudes increased, and action potential durations and input resistances decreased. The frequency of occurrence of afterhyperpolarizations and of anomalous rectification increased with age. The primary response to local extracellular stimulation was a depolarization usually accompanied by an action potential. Evoked hyperpolarizing responses were seen after P28 but only occurred if the membrane was depolarized by intracellular current injection. Cells identified by intracellular injection of Lucifer yellow were primarily medium-sized spiny neurons although it was not always possible to determine the cell type in slices from animals less than P5. Somatic diameter, dendritic length, and spine density increased with age. Dye-coupling occurred in slices less than P20. Its frequency decreased with age. These results show that Cd neurons undergo significant maturation during late prenatal and early postnatal periods. In contrast, substantia nigra neurons mature more rapidly and should be capable of influencing the less mature Cd neurons during development.(ABSTRACT TRUNCATED AT 250 WORDS)

Postnatal ontogenesis of dopaminergic and serotoninergic systems in rat caudate nucleus

The development and sex differences of the catecholaminergic and serotoninergic systems were studied in rat caudate nucleus by measuring dopamine, serotonin and their metabolites in male and female pups from birth up to day 30 of life. Dopamine increased regularly during the entire period studied, while its metabolites, dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), increased sharply only after day 9 of life. At birth, serotonin levels were 50% of the juvenile value; its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), increased greatly after day 6 of life. No difference was observed in male and female neurotransmitter ontogenesis. The results indicated that dopaminergic and serotoninergic systems were not mature in the caudate nucleus at birth. A functional immaturity of enzyme systems involved in neurotransmitter synthesis and/or catabolism is suggested.

Caudate neurons respond to excitatory and inhibitory amino acids in early postnatal periods in the cat

This study was designed to determine whether caudate neurons would respond to microphoretic application of glutamate and gamma-aminobutyric acid (GABA) in early postnatal periods in the cat. Extracellular recordings were performed in 175 neurons in developing kittens and 114 neurons in adult cats. At the earliest ages tested (1-10 days), caudate cells were excited by microphoretic application of glutamate and were inhibited by application of GABA. The results also indicated that caudate units have lower response thresholds to application of glutamate and GABA in early postnatal periods than in later periods. Since previous findings indicated that synaptically mediated inhibitory potentials develop during later postnatal periods in the cat, the present findings suggest that receptors for GABA may be capable of functioning before presynaptic endings make operational contacts.

Developmental regulation of nerve growth factor and its receptor in the rat caudate-putamen

In prior studies, nerve growth factor (NGF) administration induced a robust, selective increase in the neurochemical differentiation of caudate-putamen cholinergic neurons. In this study, expression of NGF and its receptor was examined to determine whether endogenous NGF might serve as a neurotrophic factor for these neurons. The temporal pattern of NGF gene expression and the levels of NGF mRNA and protein were distinct from those found in other brain regions. NGF and high-affinity NGF binding were present during cholinergic neurochemical differentiation and persisted into adult-hood. An increase in NGF binding during the third postnatal week was correlated with increasing choline acetyltransferase activity. The data are consistent with a role for endogenous NGF in the development and, possibly, the maintenance of caudate-putamen cholinergic neurons.

Ultrastructural alterations in caudate nucleus in aged cats

These studies provide information on the changes in the ultrastructure in the caudate nucleus of aged cats. The major finding was that there was a decrease in the density of synapses in caudate neuropil. This decrease occurred in animals after 3 years of age and remained relatively constant in older animals. In conjunction with this change a population of unusually long synapses also occurred. These larger synaptic appositions were associated with enlarged spine heads. The caudate also showed a number of qualitative ultrastructural alterations. Many neurons contained accumulations of lipofuscin or lipopigment granules in aged animals. These inclusions occurred in both soma and dendrites of neurons and all types of glial cells. A unique configuration of collapsed agranular cisterns also was observed in aged animals. The present results indicate that decreases in synaptic density may be one morphological event underlying functional alterations observed in caudate neurons in aged cats.

Glycoconjugate boundaries during early postnatal development of the neostriatal mosaic

The dispositions of galactosyl-containing glycoconjugates were studied during postnatal development of the caudate putamen in mice. The binding of the lectin peanut agglutinin, which has an affinity for galactosyl B-1,3 N-acetylgalactosamine residues, was compared to acetylcholinesterase staining and tyrosine hydroxylase immunoreactivity in the immature and adult neostriatum. The binding of peanut agglutinin conjugated to horseradish peroxidase, in sections that were processed for peroxidase histochemistry, was extremely pronounced in the neostriatum through the first postnatal week and constituted ringlike or polygonally shaped structures, which, overall, produced a variegated mosaic. These structures consist of outer rims of dense lectin-associated reaction product surrounding lightly labeled centers. Lectin delineations of the neostriatal mosaic are no longer visible in the second postnatal week. When adjacent sections were processed for lectin binding or acetylcholinesterase histochemistry, the dense lectin binding sites represented borders of acetylcholinesterase-rich and -poor zones. The distribution of dense patches of tyrosine hydroxylase immunoreactive fibers and terminals also coincides with the acetylcholinesterase-rich zones during the same times, and thus the glycoconjugate-delineated boundaries can also be directly compared with the distribution of nigrostriatal dopaminergic projections. The findings presented here represent the first demonstration of a probe that recognizes apparent borders of neostriatal compartments during a limited period of development. They are consistent with previous observations made on transient glycoconjugate "hidden boundaries" during development of other central nervous system structures, including the somatosensory cortical barrel field, and thalamic and brainstem nuclei (Cooper and Steindler, '86a,b; Steindler and Cooper, in press). In those studies, glia were shown to be the major source of glycoconjugate-associated patterns, and thus, glia and glycoconjugates that they synthesize during pattern formation events may be involved in the formation and stabilization of neurochemically distinct components of the neostriatal mosaic.

NGF effects on developing forebrain cholinergic neurons are regionally specific

Nerve growth factor (NGF) has been shown to have an effect on neurons in the central nervous system (CNS). A number of observations suggest that NGF acts as a trophic factor for cholinergic neurons of the basal forebrain and the caudate-putamen. We sought to further characterize the CNS actions of NGF by examining its effect on choline acetyltransferase (ChAT) activity in the cell bodies and fibers of developing neurons of the septum and caudate-putamen. ChAT activity was increased after even a single NGF injection. Interestingly, the magnitude of the effect of multiple NGF injections suggested that repeated treatments may augment NGF actions on these neurons. The time-course of the response to NGF was followed after a single injection on postnatal day (PD) 2. NGF treatment produced long-lasting increases in ChAT activity in septum, hippocampus and caudate-putamen. The response in cell body regions (septum, caudate-putamen) was characterized by an initial lag period of approximately 24 hr, a rapid rise to maximum values, a plateau phase and a return to baseline. The response in hippocampus was delayed by 48 hr relative to that in septum, indicating that NGF actions on ChAT were first registered in septal cell bodies. Finally, developmental events were shown to have a regionally specific influence on the response of neurons to NGF. For though the septal response to a single NGF injection was undiminished well into the third postnatal week, little or no response was detected in caudate-putamen at that time. In highlighting the potency and regional specificity of NGF effects, these observations provide additional, support for the hypothesis that NGF is a trophic factor for CNS cholinergic neurons.

Alterations in [3H]desmethylimipramine binding in the aged rat brain: an in vitro autoradiographic demonstration

Using in vitro autoradiographic receptor binding, the present report provides a descriptive analysis of [3H]desmethylimipramine ([3H]DMI) binding in the aged rat brain. Small circular patches of intense [3H]DMI binding were present within the caudate nucleus in every aged brain examined. Occasionally, similar patches of label were present in restricted cortical regions of aged brains. Comparable patches of [3H]DMI binding were never observed in young brains used in these investigations. Additional evidence suggests that these age-dependent changes in [3H]DMI binding are anatomically restricted to the loci indicated above.