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PubMed1990

Cellular gene expression for calbindin-D28k in mouse kidney.

Gene expression for calbindin-D28k, the 28,000 relative molecular mass vitamin D-dependent calcium-binding protein, was measured in cells of the murine nephron by in situ hybridization on tissue sections (hybridization cytochemistry). Radiolabeled (35S-UTP), single-stranded RNA complementary to calbindin-D28k-mRNA (probe RNA) was prepared from linearized cDNA template and used for the hybridizations. Autoradiography was carried out and cellular levels of hybridization signal (silver grains) were quantified. After correction for background the concentration of silver grains was more than 350% greater in the distal tubule than in either the proximal tubule or the glomerulus. The relative cellular level of mRNA in the cytoplasm, as reflected in silver grains/cell, of the distal tubules with probe RNA was 3.4 times greater than that with control RNA. Cells of the distal tubule were the only apparent sites of specific hybridization with probe RNA. The presence of calbindin-D28k-mRNA in the distal tubule corresponded to the localization of calbindin-D28k by immunocytochemistry.

Animals↗

PubMed1990

Immunohistochemical localization of calbindins (28K and 9K) in the tissues of the baboon Papio ursinus.

An indirect immunoperoxidase procedure was used to detect the presence of calbindin-D28K and calbindin-D9K in the cerebellum, kidney, and duodenum of the baboon Papio ursinus. Antibodies to chick calbinding-D28K and to both rat and mouse calbindin-D9K were used. The cerebellum and kidney were shown to contain calbindin-D28K; the doudenum contained calbindin-D9K. In the cerebellum, positive staining was found in the Purkinje cells only; in the kidney, positive staining was found in the distal convoluted tubules, connecting tubules, and collecting tubules, extending deep into the medullary regions of the kidney. Staining in the duodenum was confined to the enterocytes of the villi, with no stain present in the crypt regions or goblet cells. Thus the baboon, a primate, contains the larger of the calbindins in both the cerebellum and kidney as does the human and monkey, but its distribution in the kidney is more generalized than that found in humans. The molecular weight of calbindin-D9K was found to be similar to that found in other animals. However, the calbindin-D28K from the baboon tissues appears to be slightly smaller than the protein found in other animals and may therefore be of similar size to the human calbindin-D28K (Mr 26,000).

Animals↗

PubMed1994

Occurrence and localization of calbindin-D28K in kidney and cerebellum of the slider turtle, Trachemys scripta.

BACKGROUND: Since its initial discovery in the avian intestine, calbindin-D28K has been reported to occur in various species and tissues. Although calbindin-D28K binds calcium ions in the physiologically relevant range of intracellular calcium, its functional role in the various cell types where it has been localized remains unknown. METHODS: We examined the occurrence of calbindin-D28K in the brain and kidney of the testudine reptile, Trachemys scripta, by immunoblotting and immunocytochemistry using rabbit anti-sera directed against rat renal calbindin-D28K and chicken intestinal calbindin-D28K. RESULTS: Immunoblotting revealed the presence of calbindin-D28K in the turtle tissues. A single immunoreactive band in the 28,000 relative molecular mass region was visualized in cerebellar and renal homogenates. Immunocytochemistry revealed reaction product for the presence of calbindin-D28K in the Purkinje cells of the cerebellum, and in the distal tubular cells of the nephron. Processes as well as the perikaryon of the Purkinje cell were immunoreactive. CONCLUSION: This study describes the occurrence and cellular localization of calbindin-D28K in a reptilian cerebellum, and confirms the phylogenetic distribution of renal calbindin-D28K to the oldest major reptilian group.

Animals↗

PubMed2002

Neurochemical organization of the human basal ganglia: anatomofunctional territories defined by the distributions of calcium-binding proteins and SMI-32.

The distribution of the calcium-binding proteins calbindin-D28K (CB), parvalbumin (PV) and calretinin (CR), and of the nonphosphorylated neurofilament protein (with SMI-32) was investigated in the human basal ganglia to identify anatomofunctional territories. In the striatum, gradients of neuropil immunostaining define four major territories: The first (T1) includes all but the rostroventral half of the putamen and is characterized by enhanced matriceal PV and SMI-32 immunoreactivity (-ir). The second territory (T2) encompasses most part of the caudate nucleus (Cd) and rostral putamen (PuT), which show enhanced matriceal CB-ir. The third and fourth territories (T3 and T4) comprise rostroventral parts of Cd and PuT characterized by complementary patch/matrix distributions of CB- and CR-ir, and the accumbens nucleus (Acb), respectively. The latter is separated into lateral (prominently enhanced in CB-ir) and medial (prominently enhanced in CR-ir) subdivisions. In the pallidum, parallel gradients also delimit four territories, T1 in the caudal half of external (GPe) and internal (GPi) divisions, characterized by enhanced PV- and SMI-32-ir; T2 in their rostral half, characterized by enhanced CB-ir; and T3 and T4 in their rostroventral pole and in the subpallidal area, respectively, both expressing CB- and CR-ir but with different intensities. The subthalamic nucleus (STh) shows contrasting patterns of dense PV-ir (sparing only the most medial part) and low CB-ir. Expression of CR-ir is relatively low, except in the medial, low PV-ir, part of the nucleus, whereas SMI-32-ir is moderate across the whole nucleus. The substantia nigra is characterized by complementary patterns of high neuropil CB- and SMI-32-ir in pars reticulata (SNr) and high CR-ir in pars compacta (SNc) and in the ventral tegmental area (VTA). The compartmentalization of calcium-binding proteins and SMI-32 in the human basal ganglia, in particular in the striatum and pallidum, delimits anatomofunctional territories that are of significance for functional imaging studies and target selection in stereotactic neurosurgery.

Aged↗

PubMed2002

Patterns of expression of calcium binding proteins and neuronal nitric oxide synthase in different populations of hippocampal GABAergic neurons in mice.

We examined the expression of calcium binding proteins parvalbumin (PV), calretinin (CR), and calbindin D28K (CB), and neuronal nitric oxide synthase (nNOS) in gamma-aminobutyric acid (GABA)ergic neurons of the mouse hippocampus, with particular reference to areal and dorsoventral differences. First, we estimated the colocalization of the calcium binding proteins and nNOS. GABAergic neurons containing both PV and nNOS, i.e., PV-immunoreactive (-IR)/nNOS-IR neurons, were rare in Ammon's horn but frequent in the dentate gyrus (DG). CR-IR/nNOS-IR neurons and CB-IR/nNOS-IR neurons were frequent in Ammon's horn but rare in the DG. In the entire hippocampus, the percentage of CR-IR neurons containing nNOS was significantly higher at the ventral level (44.3%) than at the dorsal level (17.0%). The percentage of CB-IR neurons containing nNOS was also significantly higher at the ventral level (42.3%) than at the dorsal level (29.3%). Next, we estimated the numerical densities (NDs) of calcium binding protein-containing GABAergic neurons. The ND of PV-IR neurons was comparable at the dorsal (1.16 x 10(3)/mm(3)) and ventral levels (1.23 x 10(3)/mm(3)), respectively. The ND of CR-IR neurons was less at the dorsal level (0.52 x 10(3)/mm(3)) than at the ventral level (0.64 x 10(3)/mm(3)). The ND of CB-IR neurons was also less at the dorsal level (0.91 x 10(3)/mm(3)) than at the ventral level (1.57 x 10(3)/mm(3)). Overall, approximately half of the GABAergic neurons contained one of the three calcium binding proteins (45% at the dorsal level and 47% at the ventral level). These data establish a baseline for examining potential roles of GABAergic neurons in hippocampal network activity in mice.

Animals↗

PubMed2003

Synaptic connections of distinct interneuronal subpopulations in the rat basolateral amygdalar nucleus.

Although it is well established that the activity of pyramidal projection neurons in the basolateral amygdala (ABL) is controlled by gamma-aminobutyric acid (GABA)ergic inhibitory interneurons, very little is known about the connections of specific interneuronal subpopulations in this region. In the present study, immunohistochemical techniques were used at the light and electron microscopic levels to identify specific populations of interneurons and to analyze their connections with each other and with unlabeled presumptive pyramidal neurons. Double-labeling immunofluorescence experiments revealed that antibodies to vasoactive intestinal peptide (VIP) and calbindin-D28K (CB) labeled two separate interneuronal subpopulations in the ABL. Light microscopic double-labeling immunoperoxidase experiments demonstrated that many VIP-positive (VIP+) axon terminals formed intimate synaptic-like contacts with the CB-positive (CB+) neurons and that both CB+ and VIP+ terminals often contributed to the formation of pericellular baskets that surrounded unlabeled perikarya of pyramidal neurons. By using a dual immunoperoxidase/immunogold-silver procedure at the ultrastructural level, it was found that 30% of VIP+ terminals in the anterior subdivision of the basolateral nucleus innervated interneurons that were either CB+ (25%) or VIP+ (5%). A smaller percentage (15%) of CB+ terminals formed synapses with labeled interneurons. Both VIP+ and CB+ terminals also innervated unlabeled perikarya, dendrites, and spines, most of which probably belonged to pyramidal neurons. The interconnections between interneurons may be important for disinhibitory mechanisms and the mediation of rhythmic oscillations in the ABL.

Amygdala↗

PubMed2003

Loss of calbindin-D28k from aging human cholinergic basal forebrain: relation to neuronal loss.

Cholinergic neurons of the basal forebrain (BFCN) are selectively vulnerable in neurodegenerative disorders of the elderly, particularly in Alzheimer's disease (AD). We investigated age-related changes in the BFCN that may serve as a substrate for this vulnerability. We report a substantial and selective age-related loss of the calcium binding protein calbindin-D(28K) (CB) from the human BFCN. Unbiased stereological estimation indicated that, in individuals under age 65 years, 72% of the choline acetyltransferase (ChAT)-positive BFCN contained CB immunoreactivity. In individuals over age 65 years, only 28% of the BFCN contained CB immunoreactivity, a dramatic loss of 61%. Similar results were obtained using neuronal counts from matching single- or double-stained sections in a larger cohort. The loss of CB immunoreactivity was neurochemically specific. No age-related changes were observed in the number of ChAT- or low-affinity nerve growth factor receptor (p75(NTR))-immunoreactive profiles. The loss of CB was greatest in very old individuals, in whom a small loss of BFCN was observed. Furthermore, the loss of CB displayed the same pattern as the loss of BFCN in AD and was more substantial in the posterior compared with the anterior BFCN sector, suggesting a role for CB in the selective vulnerability of BFCN in AD. The depletion of CB from the BFCN is likely to deprive these neurons of the capacity to buffer high levels of intracellular Ca(2+) and thus to leave them vulnerable to pathological processes, such as those in neurodegenerative disorders, which can cause increased intracellular Ca(2+), thus leading to their degeneration.

Adult↗

PubMed2003

Cortical and brainstem neurons containing calcium-binding proteins in a murine model of Duchenne's muscular dystrophy: selective changes in the sensorimotor cortex.

In the muscular dystrophic (mdx) mouse, which is characterized by deficient dystrophin expression and provides a model of Duchenne's muscular dystrophy, we previously demonstrated marked central nervous system alterations and in particular a quantitative reduction of corticospinal and rubrospinal neurons and pathologic changes of these cells. Prompted by these findings and in view of the relations between calcium ions and dystrophin, we analyzed with immunohistochemistry the neurons containing the calcium-binding proteins parvalbumin, calbindin D28k, and calretinin in cortical areas and brainstem nuclei of mdx mice. In the sensorimotor cortex, parvalbumin-positive and calbindin-positive neurons, which represent a subset of cortical interneurons, were significantly more numerous in mdx mice than in wild-type ones. In addition, the laminar distribution of parvalbumin-positive neurons in the motor and somatosensory cortical areas of mdx mice was altered with respect to wild-type animals. No alterations in the number and distribution were found in the parvalbumin- or calbindin-expressing cell populations of the visual and anterior cingulate cortices of mdx mice. The pattern of calretinin immunoreactivity was normal in all investigated cortical areas. The cell populations containing either calcium-binding protein were similar in brainstem nuclei of mdx and wild-type mice. The present findings demonstrated selective changes of subsets of interneurons in the motor and somatosensory cortical areas of mdx mice. Therefore, the data showed that, in the cortices of these mutant animals, the previously demonstrated pathologic changes of corticospinal cell populations are accompanied by marked alterations in the local circuitry.

Animals↗

PubMed2003

Differential distribution of calbindin D28k and parvalbumin among functionally distinctive sets of structures in the macaque brainstem.

In a study of brainstem in the cynomolgus monkey, we found that the distribution of calbindin D28K (CB) and parvalbumin (PV) is nonoverlapping among functionally distinct sets of brainstem structures. Nuclei involved in representation and regulation of the organism's internal state contain CB, whereas those involved in the representation of the external environment and the representation or execution of externally directed actions contain only PV. Moreover, our findings indicate that different nuclei known as components of the ascending reticular activating system (ARAS) contain either CB or PV or both, suggesting that this system in primates operates with both CB and PV. In line with previously reported findings, we also found that unmyelinated pathways contain only CB, whereas myelinated pathways contain PV. Distribution of CB and PV in the macaque brainstem follows a pattern comparable to, but in some instances significantly different than, the pattern previously reported in the rat. We argue that the nonoverlapping distribution of CB and PV among different structures of the brainstem might reflect underlying differences in the physiological, anatomic, and perhaps phylogenetic properties of these structures. Considering our recent findings of selective vulnerability of brainstem structures to Alzheimer's disease, the present data suggest that the majority of macaque brainstem nuclei that contain CB are vulnerable to neurofibrillary tangles in humans. By contrast, only few nuclei that contain PV exhibit pathologic changes. Some of these nuclei are affected with a high number of neuritic plaques without ever developing neurofibrillary tangles.

Animals↗

PubMed2004

Development of the human motor-related thalamic nuclei during the first half of gestation, with special emphasis on GABAergic circuits.

This study analyzed the expression of differentiation markers (Calbindin D28K: CaBP; parvalbumin: PARV; calretinin: CalR), gamma-aminobutyric acid (GABA) markers (GABA, glutamic acid decarboxylases: GAD65, GAD67; and GABA transporters: GAT1, GAT3), and other markers (neurotensin: NT, and neurofilament-specific protein: SMI32) in the human thalamus at 8-23 gestation weeks (g.w.), focusing on the motor-related nuclei. From 8-13 g.w. mainly CaBP was expressed in the cells while fiber bundles traversing the thalamus in addition to CaBP expressed all GABA markers except GAD67. CaBP and PARV expression patterns in different nuclei changed over the time course studied, whereas NT was expressed consistently along the anterior-lateral curvature of the thalamus. CalR and SMI were detectable at 23 g.w. in the ventral parts of the dorsal thalamus. Most remarkably, punctate GAD65 immunoreactivity in the neuropil was confined to the nigro- and pallidothalamic afferent receiving nuclei from 16 to about 21 g.w., overlapping with that of CaBP in some of these nuclei (subdivisions of the ventral anterior and mediodorsal nuclei) and with PARV in others (centromedian nucleus). During this period, GAD65 immunoreactivity can be considered a marker of the basal ganglia afferent receiving territory in the motor thalamus. GAD67-positive local circuit neurons were first detected at 12-13 g.w. in the thalamic nuclei outside the basal ganglia afferent receiving territory. In the ventral anterior and centromedian nuclei, GAD-containing local circuit neurons were not conspicuous even at 22-23 g.w. The cells of the reticular nucleus expressed GAD67 and PARV from 12 g.w. on starting in the lateral-posterior regions. By 23 g.w., both markers were expressed in about two-thirds of the nucleus except for its most medial-anterior part. The results imply spatially and temporally differential expression of GABA and differentiation markers in the developing human thalamus.

Biomarkers↗

PubMed1989

Ultrastructural localization of immunoreactive calbindin-D28k in the rat and monkey basal ganglia, including subcellular distribution with colloidal gold labeling.

Normal cellular function depends on the controlled flux of Ca++ within intracellular compartments and across the plasma membrane. Proteins that bind Ca++ are thought to contribute to the regulation of intracellular Ca++ and, perhaps more importantly, signal functional changes in cell activity. In the brain, calbindin-D28k is among a class of calcium-binding proteins that are widely and heterogeneously distributed in select populations of neurons, among them neostriatal cells, but whose function is largely unknown. In this study of the monkey and rat neostriatum and globus pallidus, calbindin-D28k was localized with immunoperoxidase and immunogold methods in order to identify striatal cell populations that contain this protein and the subcellular compartments in which it is likely to function. Light and electron microscopy showed intense and extensive labeling of immunoreactive calbindin-D28k in the cell bodies, dendrites, and spines of medium-sized neostriatal spiny neurons and in their axon terminals which end in the globus pallidus. More discrete labeling with a gold-conjugated second antibody showed that the predominant site of calbindin-D28k was the matrix of the cytoplasm. Gold label was also associated with the karyoplasm of spiny cells and with the neurofilaments and axoplasmic matrix of striatopallidal axons and terminals, respectively. Membranes were either sparsely labeled (endoplasmic reticulum, mitochondria) or devoid of gold particles (nuclear envelope and plasmalemma). Radioimmunoassays of striatal subcellular fractions supported the anatomical findings by indicating that the soluble fractions of neostriatal tissue homogenates contained most of the calbindin-D28k immunoreactivity and that washes from forebrain synaptosomes treated with Triton X-100 yielded high levels of immunoreactive calbindin-D28k. These findings show that immunoreactive calbindin-D28k is localized to spiny neurons of the striatopallidal pathway and are consistent with previous observations on subcellular localization in nonneuronal tissues. If, as recently speculated, calbindin-D28k regulates calcium concentrations in neostriatal spiny neurons, this feature may be particularly involved with the high density of glutamatergic inputs to these cells. More work is needed to determine whether calbindin-D28k, when complexed to Ca++ in neostriatal spiny cells, signals the activation of protein kinases, phosphorylation, and/or neurotransmitter release, as has been shown for other Ca++-binding proteins in mammalian tissues.

Animals↗

PubMed1990

Parvalbumin-containing GABAergic interneurons in the rat neostriatum.

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

Animals↗

PubMed1991

Calcium-binding protein (calbindin-D28K) and parvalbumin immunocytochemistry in the normal and epileptic human hippocampus.

The calcium-binding proteins calbindin-D28K (CaBP) and parvalbumin (PV) were localized in the "normal" and "epileptic" human hippocampus to address the possible relationship between the expression of these constitutive cytosolic calcium-binding proteins and the resistance or selective vulnerability of different hippocampal neuron populations in temporal lobe epilepsy. Compared to rodents and a baboon (Papio papio), the pattern of CaBP-like immunoreactivity (LI) in the "normal" human hippocampus is unique. CaBP-LI is present in the dentate granule cells, neurons of the "resistant zone" (area CA2), and presumed interneurons of all regions. Unlike rodent and baboon CA1 pyramidal cells, human CA1 pyramidal cells appear to be devoid of CaBP-LI. Thus, the relatively resistant dentate granule cells and CA2 pyramidal cells are the only human hippocampal principal cells that contain CaBP-LI normally. As in lower mammals, PV-LI is present exclusively in interneurons of all human hippocampal subregions. CaBP- and PV-LI were localized in hippocampi surgically removed in the treatment of intractable temporal lobe epilepsy to determine whether surviving hippocampal cells were those that express these calcium-binding proteins. Hippocampi removed from patients with tumors or arteriovenous malformations that were associated with complex partial seizures arising from this region appeared relatively normal histologically. CaBP- and PV-LI in this patient group appeared similar to that seen in autopsy controls. Conversely, "cryptogenic" epileptics, who exhibit hippocampal sclerosis as the only lesion associated with the epilepsy, exhibited a preferential survival of hippocampal cells that were CaBP- or PV-immunoreactive. In the dentate hilus, which normally contains few CaBP-LI neurons, most of the few surviving hilar neurons were CaBP-immunoreactive. Their number and darkness of staining suggests that CaBP synthesis may be increased in cells that survive. Despite an obvious decrease of PV-LI specifically in the damaged parts of the sclerotic hippocampi, PV-immunoreactive interneurons were often among the few surviving cells. Nevertheless, large expanses of the surviving granule cell layer appeared to have lost the PV-immunoreactive axosomatic fiber plexus. These results reveal a unique and striking correlation between the human hippocampal cells that normally express these calcium-binding proteins and those that survive in the sclerotic epileptic hippocampus.

Adult↗

PubMed1991

Subpopulations of GABAergic neurons containing parvalbumin, calbindin D28k, and cholecystokinin in the rat hippocampus.

The possible coexistence of calbindin D28k with parvalbumin and of calbindin D28k with cholecystokinin was studied in nonpyramidal cells of the rat dorsal hippocampal formation. Neighbouring Vibratome sections were immunostained either for calbindin D28k and parvalbumin or for calbindin D28k and cholecystokinin. The cells, halved during sectioning, were identified in both sections immunostained for different antigens. The coexistence of calbindin D28k and parvalbumin in the same neuron was rare throughout the hippocampal formation with the exception of stratum oriens of the CA1 region, where 9.6% of the parvalbumin-immunoreactive cells also contained calbindin D28k. In stratum radiatum of the CA3 region, calbindin D28k and cholecystokinin coexisted in 12.5% and 21.2% of the calbindin D28k and cholecystokinin-immunoreactive cells, respectively. In other regions of the hippocampal formation, the two markers coexisted in less than 5% of the cells of either type. The present results demonstrate that calbindin D28k-, parvalbumin- and cholecystokinin-containing nonpyramidal cells represent largely nonoverlapping cell populations and may thus be involved in different inhibitory circuits.

Animals↗

PubMed1991

Different populations of parvalbumin- and calbindin-D28k-immunoreactive neurons contain GABA and accumulate 3H-D-aspartate in the dorsal horn of the rat spinal cord.

The colocalization of parvalbumin (PV), calbindin-D28k (CaBP), GABA immunoreactivities, and the ability to accumulate 3H-D-aspartate selectively were investigated in neurons of laminae I-IV of the dorsal horn of the rat spinal cord. Following injection of 3H-D-aspartate into the basal dorsal horn (laminae IV-VI), perikarya selectively accumulating 3H-D-aspartate were detected in araldite embedded semithin sections by autoradiography, and consecutive semithin sections were treated to reveal PV, CaBP and GABA by postembedding immunocytochemistry. Perikarya accumulating 3H-D-aspartate were found exclusively in laminae I-III, and no labelled somata were found in deeper layers or in the intermediolateral column although the labelled amino acid clearly spread to these regions. More than half of the labelled cells were localized in lamina II. In this layer, 16.4% of 3H-D-aspartate-labelled perikarya were also stained for CaBP. In contrast to CaBP, PV or GABA was never detected in neurons accumulating 3H-D-aspartate. A high proportion of PV-immunoreactive perikarya were also stained for GABA in laminae II and III (70.0% and 61.2% respectively). However, the majority of CaBP-immunoreactive perikarya were GABA-negative. GABA-immunoreactivity was found in less than 2% of the total population of cells stained for CaBP in laminae I-IV. A significant proportion of the GABA-negative but PV-immunoreactive neurons also showed CaBP-immunoreactivity in laminae II and IV. These results show that out of the two calcium-binding proteins, CaBP is a characteristic protein of a small subpopulation of neurons using excitatory amino acids and PV is a characteristic protein of a subpopulation of neurons utilizing GABA as a transmitter. However, both proteins are present in additional subgroups of neurons, and neuronal populations using inhibitory or excitatory amino acid transmitters are heterogeneous with regard to their content of calcium-binding proteins in the dorsal horn of the rat spinal cord.

Animals↗

PubMed1991

Calmodulin and calbindin localization in retina from six vertebrate species.

Calmodulin is abundant in the central nervous system, including the retina. However, the localization of calmodulin in the retina has not been described in detail. We therefore decided to investigate calmodulin localization in retinae from six vertebrate species, by using immunohistochemical labeling with four different rabbit polyclonal antibodies against calmodulin. The localization of calbindin-D28k, another calcium-binding protein already well described in retina, was compared. We found that calmodulin distribution is more highly conserved among species, contrasting with calbindin variability. The most striking result emerging is that calmodulin could not be detected in photoreceptors although other layers are intensely calmodulin-immunoreactive, casting doubt about a direct role of calmodulin in phototransduction. Horizontal cells are weakly calmodulin-immunoreactive, bipolar cells are calmodulin-immunoreactive except in turtle retina, numerous amacrine and ganglion cells are labeled in all species, and the fiber layer is always labeled. These data demonstrate that, while the calmodulin distribution in retina is similar among vertebrate species, selective differences in localization can be detected not only among the same cell types in different species but also among different cell types in the same species. The results showing differences in calmodulin immunoreactivity among cell types also provide further evidence that calmodulin expression in eukaryotes is not constitutive, in the sense that not every cell expresses similar levels of calmodulin.

Animals↗

PubMed1992

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.

Aging↗

PubMed1993

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

The spatial distributions and dendritic branching patterns of chemically identified subpopulations of striatal intrinsic neurons, defined by immunoreactivity for choline acetyltransferase (ChAT), neuropeptide Y or parvalbumin, were studied in relation to patch and matrix compartments of rat neostriatum. ChAT-immunoreactive cells and fibers showed an uneven pattern of distribution in the striatum. ChAT immunoreactivity was higher in the dorsolateral part and lower in the ventromedial part of the striatum. This regional gradient pattern is the inverse of the overall pattern of calbindin D28k immunoreactivity. However, in small regions close to the lateral ventricle and globus pallidus, areas containing fewer ChAT-immunoreactive cells and fibers coincided with those containing low calbindin D28k immunoreactivity. Neuropeptide Y immunoreactivity was uniform in the neostriatum. Certain neuropeptide Y cells (about 20%) were also immunoreactive for calbindin D28k, indicating that at least a small population of calbindin D28k-immunoreactive cells are medium aspiny cells. Parvalbumin immunoreactivity was not uniform in the striatum. A higher density of parvalbumin immunoreactivity was found in the neuropil in lateral and caudal parts than in the medial part. Small regions with weaker parvalbumin-immunoreactive neuropil partially corresponded to calbindin D28k poor patches. Larger cells immunoreactive for parvalbumin were preferentially located in lateral and caudal parts of the striatum. Cells immunoreactive for ChAT, neuropeptide Y or parvalbumin showed basically similar distribution patterns in relation to the patch and matrix compartments. Most stained cells were located in the matrix, but some were located at the borders of patches and a few were inside patches. Most primary dendrites of stained cells in the matrix or patches remained confined to these compartments, but cells on the borders invariably extended dendrites into both compartments. The striatal intrinsic neurons form chemically differentiated neuronal circuits within the matrix, and the patches and those whose dendrites cross the borders may contribute to associational interconnections between the two compartments, unlike the spiny projection neurons whose dendrites are confined to one or the other compartment.

Animals↗