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PubMed2005

Development of neurons and fibers containing calcium binding proteins in the pallial amygdala of mouse, with special emphasis on those of the basolateral amygdalar complex.

We studied the development of neurons and fibers containing calbindin, calretinin, and parvalbumin in the mouse pallial amygdala, with special emphasis on those of the basolateral amygdalar complex. Numerous calbindin-immunoreactive (CB+) cells were observed in the incipient basolateral amygdalar complex and cortical amygdalar area from E13.5. At E16.5, CB+ cells became more abundant in the lateral and basolateral nuclei than in the basomedial nucleus, showing a pattern very similar to that of gamma-aminobutyric acid (GABA)ergic neurons. Many CB+ cells observed in the pallial amygdala appeared to originate in the anterior entopeduncular area/ganglionic eminences of the subpallium. The density of CB+ cells gradually increased in the pallial amygdala until the first postnatal week and appeared to decrease later, coinciding with the postnatal appearance of parvalbumin cells and raising the possibility of a partial phenotypic shift. Calretinin (CR) immunoreactivity could be observed in a few cells and fibers in the pallial amygdala at E14.5, and by E16.5 it became a good marker of the different nuclei of the basolateral amygdalar complex. Numerous CB+ and CR+ varicosities, part of which have an intrinsic origin, were observed in the basolateral amygdalar complex from E16.5, and some surrounded unstained perikarya and/or processes before birth, indicating an early formation of inhibitory networks. Each calcium binding protein showed a distinct spatiotemporal expression pattern of development in the mouse pallial amygdala. Any alteration in the development of neurons and fibers containing calcium binding proteins of the pallial amygdala may result in important disorders of emotional and social behavior.

Amygdala↗
PubMed2005

Postnatal development of synaptopodin expression in the rodent hippocampus.

Synaptopodin is an actin-binding protein of renal podocytes and dendritic spines. We have recently shown that synaptopodin is localized to the spine apparatus, a characteristic organelle of dendritic spines on forebrain neurons. Synaptopodin-deficient mice do not form spine apparatuses, indicating a role of synaptopodin in the formation of this organelle. Here we studied the development of synaptopodin expression in the postnatal rat hippocampus. At birth, synaptopodin mRNA is mainly expressed in CA3 pyramidal neurons. At postnatal day (P) 6, synaptopodin mRNA expression is still strongest in CA3 but is now also found in CA1 pyramidal neurons and granule cells of the suprapyramidal blade of the dentate gyrus. At P9, an almost adult pattern is seen with synaptopodin mRNA expressed by virtually all principal neurons. While synaptopodin mRNA was restricted to cell somata, immunostaining for synaptopodin protein labeled dendritic layers. At birth, no immunoreactivity was visible, while at P5 a weak staining mainly in stratum oriens was observed. At P9, immunolabeling was still strongest in stratum oriens followed by the molecular layer of the dentate gyrus. The adult pattern with strong labeling of all dendritic layers was reached by P12. Together these findings show that synaptopodin expression follows the well-known sequence of hippocampal principal neuron development. Unexpectedly, we also observed synaptopodin mRNA expression in a small population of interneurons as revealed by double labeling with interneuron markers. However, no immunolabeling for synaptopodin was observed in identified interneurons, confirming that the protein is mainly present in spine-bearing principal cells.

Age Factors↗
PubMed2005

Postnatal phenotype and localization of spinal cord V1 derived interneurons.

Developmental studies identified four classes (V0, V1, V2, V3) of embryonic interneurons in the ventral spinal cord. Very little is known, however, about their adult phenotypes. Therefore, we characterized the location, neurotransmitter phenotype, calcium-buffering protein expression, and axon distributions of V1-derived neurons in the adult mouse spinal cord. In the mature (P20 and older) spinal cord, most V1-derived neurons are located in lateral LVII and in LIX, few in medial LVII, and none in LVIII. Approximately 40% express calbindin and/or parvalbumin, while few express calretinin. Of seven groups of ventral interneurons identified according to calcium-buffering protein expression, two groups (1 and 4) correspond with V1-derived neurons. Group 1 are Renshaw cells and intensely express calbindin and coexpress parvalbumin and calretinin. They represent 9% of the V1 population. Group 4 express only parvalbumin and represent 27% of V1-derived neurons. V1-derived Group 4 neurons receive contacts from primary sensory afferents and are therefore proprioceptive interneurons. The most ventral neurons in this group receive convergent calbindin-IR Renshaw cell inputs. This subgroup resembles Ia inhibitory interneurons (IaINs) and represents 13% of V1-derived neurons. Adult V1-interneuron axons target LIX and LVII and some enter the deep dorsal horn. V1 axons do not cross the midline. V1-derived axonal varicosities were mostly (>80%) glycinergic and a third were GABAergic. None were glutamatergic or cholinergic. In summary, V1 interneurons develop into ipsilaterally projecting, inhibitory interneurons that include Renshaw cells, Ia inhibitory interneurons, and other unidentified proprioceptive interneurons.

Animals↗
PubMed2006

Distribution and chemical coding of corticotropin-releasing factor-immunoreactive neurons in the guinea pig enteric nervous system.

Immunofluorescence was used to study immunoreactivity (IR) for corticotropin-releasing factor (CRF) in the guinea pig enteric nervous system. CRF-IR was expressed in both the myenteric and the submucosal plexuses of all regions of the large and small intestine and the myenteric plexus of the stomach. CRF-IR nerve fibers were present in the myenteric and submucosal plexuses, in the circular muscle coat, and surrounding submucosal arterioles. Most of the CRF-IR fibers persisted in the myenteric and submucosal plexuses after 7 days in organotypic culture. CRF-IR was not coexpressed with tyrosine hydroxylase-IR or calcitonin gene-related peptide-IR fibers. The proportions of CRF-IR cell bodies in the myenteric plexus increased progressively from the stomach (0.6%) to the distal colon (2.8%). Most of the CRF-IR myenteric neurons (95%) had uniaxonal morphology; the remainder had Dogiel type II multipolar morphology. CRF-IR cell bodies in the myenteric plexus of the ileum expressed IR for choline acetyltransferase (56.9%), substance P (55.0%), and nitric oxide synthase (37.9%). CRF-IR never colocalized with IR for calbindin, calretinin, neuropeptide Y, serotonin, or somatostatin in the myenteric plexus. CRF-IR cell bodies were more abundant in the submucosal plexus (29.9-38.0%) than in the myenteric plexus. All CRF-IR neurons in submucosal ganglia expressed vasoactive intestinal peptide-IR and were likely to be secretomotor/vasodilator neurons. CRF-IR neurons did not express IR for the CRF(1) receptor. CRF(1)-IR was expressed in neuronal neighbors of those with CRF-IR. Collective evidence suggests that VIPergic secretomotor neurons might provide synaptic input to neighboring cholinergic neurons.

Animals↗
PubMed2006

Immunohistochemical localization of calbindin-D28k and calretinin in the spinal cord of Xenopus laevis.

Immunohistochemical techniques were used to investigate the distribution and morphology of neurons containing the calcium-binding proteins calbindin-D28k (CB) and calretinin (CR) in the spinal cord of Xenopus laevis and determine the extent to which this organization is comparable to that of mammals. Most CB- and CR-containing neurons were located in the superficial dorsal gray field, but with distinct topography. The lateral, ventrolateral, and ventromedial fields also possessed abundant neurons labeled for either CB or CR. Double immunohistofluorescence demonstrated that a subpopulation of dorsal root ganglion cells and neurons in the dorsal and ventrolateral fields contained CB and CR. By means of a similar technique, a cell population in the dorsal field was doubly labeled only for CB and nitric oxide synthase (NOS), whereas in the ventrolateral field colocalization of NOS with CB and CR was found. Choline acetyltransferase immunohistochemistry revealed that a subpopulation of ventral horn neurons, including motoneurons, colocalized CB and CR. The involvement of CB- and CR-containing neurons in ascending spinal projections was demonstrated combining the retrograde transport of dextran amines and immunohistochemistry. Cells colocalizing the tracer and CB or CR were quite numerous, primarily in the dorsal and ventrolateral fields. Similar experiments demonstrated supraspinal projections from CB- and CR-containing cells in the brainstem and diencephalon. The distribution, projections, and colocalization with neurotransmitters of the neuronal systems containing CB and CR in Xenopus suggest that CB and CR are important neuromodulator substances with functions conserved in the spinal cord from amphibians through mammals.

Animals↗
PubMed2006

Calcium-binding proteins, neuronal nitric oxide synthase, and GABA help to distinguish different pallial areas in the developing and adult chicken. I. Hippocampal formation and hyperpallium.

To better understand the formation and adult organization of the avian pallium, we studied the expression patterns of gamma-aminobutyric acid (GABA), calbindin (CB), calretinin (CR), and neuronal nitric oxide synthase (nNOS) in the hippocampal formation and hyperpallium of developing and adult chicks. Each marker showed a specific spatiotemporal expression pattern and was expressed in a region (area)-specific but dynamic manner during development. The combinatorial expression of these markers was very useful for identifying and following the development of subdivisions of the chicken hippocampal formation and hyperpallium. In the hyperpallium, three separate radially arranged subdivisions were present since early development showing distinct expression patterns: the apical hyperpallium (CB-rich); the intercalated hyperpallium (nNOS-rich, CB-poor); the dorsal hyperpallium (nNOS-poor, CB-moderate). Furthermore, a novel division was identified (CB-rich, CR-rich), interposed between hyper- and mesopallium and related to the lamina separating both, termed laminar pallial nucleus. This gave rise at its surface to part of the lateral hyperpallium. Later in development, the interstitial nucleus of the apical hyperpallium became visible as a partition of the apical hyperpallium. In the hippocampal formation, at least five radial divisions were observed, and these were compared with the divisions proposed recently in adult pigeons. Of note, the corticoid dorsolateral area (sometimes referred as caudolateral part of the parahippocampal area) contained CB immunoreactivity patches coinciding with Nissl-stained cell aggregates, partially resembling the patches described in the mammalian entorhinal cortex. Each neurochemical marker was present in specific neuronal subpopulations and axonal networks, providing insights into the functional maturation of the chicken pallium.

Animals↗
PubMed2006

Co-occurrence of calcium-binding proteins and calcium-permeable glutamate receptors in the primary gustatory nucleus of goldfish.

Primary vagal gustatory afferents utilize glutamate as a neurotransmitter acting on AMPA/kainate receptors of second-order neurons. Some forms of ionotropic glutamate receptors permit passage of Ca++ ions upon activation by appropriate ligands. Calcium-binding proteins (CaBPs) play a buffering role for regulating the concentration of intracellular calcium. In the present study, we used immunohistochemistry to examine the distribution and morphology of neurons with CaBPs, including calretinin, calbindin, and parvalbumin, and to compare this distribution with neurons exhibiting Ca++-permeable glutamate receptors as determined by kainate-stimulated uptake of Co++ in the vagal lobe of goldfish. Calretinin- and calbindin-positive neurons occurred throughout the sensory zone including round unipolar, horizontal; and perpendicular bipolar or multipolar somata. Parvalbumin neurons were mainly round monopolar neurons, especially common in the superficial layers of the sensory zone. In the motor zone, while parvalbumin labeled nearly all motoneurons, calretinin labeled only external motoneurons. In double labeling with calretinin and parvalbumin, few neurons in the sensory layer labeled with both antisera. Immunocytochemistry following kainate-stimulate uptake of Co++ showed that most calretinin, but few parvalbumin immunopositive neurons also were labeled by cobalt in the central and deep layers of the sensory zone. All motoneurons were labeled by Co++, including those immunoreactive for calretinin or parvalbumin. These results indicate that calretinin expression is strongly correlated with calcium-permeable ionotropic glutamate receptors in the neurons of the sensory zone of the goldfish vagal lobe, but even within this limited region, not all Ca++-permeable neurons possess any of the CaBPs examined.

Animals↗
PubMed2007

Origins and migratory routes of murine Cajal-Retzius cells.

The first layer that appears in the cortical neuroepithelium, the preplate, forms in the upper part of the cortex immediately below the pial surface. In mice, this layer exists between embryonic days (E) 10 and 13, and it hosts different cell populations. Here, we have studied the first cell population generated in the preplate, the Cajal-Retzius cells. There is considerable confusion regarding these cells with respect to both their site of generation and the migratory routes that they follow. This perhaps is due largely to the different opinions that exist regarding their characterization. We have studied the site of origin of these cells, their migratory routes, and the molecular markers that may distinguish them by injecting tracers into early embryos, culturing them in toto for 24 hours, and then performing immunohistochemistry. We found that the Cajal-Retzius cells are most likely generated in the cortical hem by comparing with other cortical or extracortical origins. These cells are generated mainly at E10 and E11, and they subsequently migrate tangentially to cover the whole cortical mantle in 24 hours. From their site of origin in the medial wall of the telencephalon, they spread in a caudorostral direction, following an oblique migratory path toward the lateral part of the neuroepithelium. Prior to the splitting of the preplate, a percentage of the Cajal-Retzius cells that can be distinguished by the expression of reelin do not contain calretinin. Furthermore, there were no early-migrating neurons that expressed calbindin.

Animals↗
PubMed1992

Distribution of GABAergic interneurons immunoreactive for calretinin, calbindin D28K, and parvalbumin in the cerebral cortex of the lizard Podarcis hispanica.

The types and distribution of cells containing three calcium-binding proteins, calretinin, calbindin D28K, and parvalbumin, have been studied by immunocytochemistry in different areas of the cerebral cortex of lizards. Cross-reactivity of the antisera has been excluded by demonstrating the existence of several cell groups immunoreactive for one but not the other two calcium-binding proteins. In the dorsal and dorsomedial cortices all three proteins coexist in a single subpopulation of gamma-aminobutyric acid (GABA)ergic neurons, the terminals of which form pericellular baskets around cell bodies of bipyramidal neurons. The somata of these neurons are largely restricted to the cellular and inner plexiform layers, but the dendrites usually penetrate all layers, allowing the neurons to sample input from all possible sources. A small number of parvalbumin-containing neurons in the outer plexiform layer do not contain the other two proteins. The medial cortex, which is likely to be homologous to the mammalian dentate gyrus, only contains parvalbumin-immunoreactive neurons. The dendritic trees of these cells appear to avoid the Timm-positive fields receiving input from zinc-rich fiber collaterals, originating from principal cells. The lateral cortex contains calbindin D28K-immunoreactive GABAergic neurons, which lack the other two calcium-binding proteins. These neurons have horizontally running dendrites in the outer plexiform layer, but their axon terminals could not be visualized. The present study uncovered important similarities and differences between the lizard and the mammalian archicortex in the types of neurons containing calcium-binding proteins. As in mammals, different cell types evolved in the lizard to inhibit the perisomatic versus the distal dendritic region of principal cells, the calcium-binding protein-containing neurons being responsible for the former, and neuropeptide-containing neurons for the latter. The results also suggest that further neurochemical diversion of GABAergic interneurons coupled to a functional specialization took place during phylogenetic development from reptiles to mammals.

Animals↗
PubMed1994

New subdivision schema for the avian torus semicircularis: neurochemical maps in the chick.

Chemoarchitectonic subdivisions in the chicken torus semicircularis were mapped by means of acetylcholinesterase histochemistry and immunocytochemical labeling of leucine-enkephalin, choline acetyltransferase, neuropeptide Y, and calbindin/calretinin in adjacent sections. The torus semicircularis was found to consist of three main divisions: intercollicular area, toral nucleus, and preisthmic superficial area. All three appear variously subdivided. The intercollicular area is a mid-mesencephalic ventral periventricular region and appears subdivided into core and shell intercollicular regions. The toral nucleus is formed by a large caudal periventricular cytoarchitectonic complex, consisting of a periventricular lamina subdivided into core and shell regions, a pericentral, diffuse external nucleus, a central nucleus subdivided into core and shell regions, a caudomedial shell nucleus, a paracentral nucleus, and a posterior hiliar nucleus, apart from other minor parcellations. The preisthmic superficial area extends superficially at the caudomedial end of the toral nucleus, reaching the paramedian dorsal brain surface just rostral to the isthmo-optic nucleus. It is subdivided into core and shell regions. This previously unnoticed area is distinguished here from the intercollicular area and from the caudomedial shell and paracentral nuclei, all of which are frequently mixed in the literature under the concept "intercollicular nucleus." The revised terminology and subdivision for the avian torus clarifies many chemoarchitectonic and hodological mappings reported in the literature. It also suggests new research subjects and eliminates some causes of confusion.

Acetylcholinesterase↗
PubMed1994

Immunohistochemical localization of calbindin-D28K and calretinin in the lamprey retina.

Calbindin-D28K and calretinin are homologous cytosolic calcium binding proteins localized in many retinal neurons from different species. In this report, location of cells immunoreactive to both proteins was investigated in the retina of the lamprey, Lampetra fluviatilis. This organism constitutes one of the older representative vertebrates and possesses a peculiar organization, probably unique: two-thirds of the ganglion cells are in the classical amacrine cell layer and the nerve fiber layer is located in the scleral part of the inner plexiform layer. Calbindin-like immunoreactivity was demonstrated in large bipolar cells and in cell bodies located in the inner retina. Although the distinction between labelled ganglion cells and labelled amacrine cells was rendered difficult, we hypothesized that the majority of calbindin-immunoreactive cells observed in the inner retina are ganglion cells, because of the high number of labelled fibers in the nerve fiber layer. Calretinin-like immunoreactivity was detected in both large and small bipolar cells, and also in cells located in the inner retina. Since few calretinin-immunoreactive fibers were observed in the nerve fiber layer, we assume that the latter category of cells are amacrine cells. Horizontal cells were both negative for calbindin and calretin-like immunoreactivities. Calbindin and calretinin, which are present in cones from many species, could not be detected in the photoreceptor layer favouring the rod-dominated lamprey retina. Although their distribution differs from those observed in most vertebrates, the present results indicate the good conservation of both calcium binding proteins in the retina during the vertebrate evolution.

Animals↗
PubMed1994

Local circuit neurons immunoreactive for calretinin, calbindin D-28k or parvalbumin in monkey prefrontal cortex: distribution and morphology.

In the cerebral cortex, local circuit neurons provide critical inhibitory control over the activity of pyramidal neurons, the major class of excitatory efferent cortical cells. The calcium-binding proteins, calretinin, calbindin, and parvalbumin, are expressed in a variety of cortical local circuit neurons. However, in the primate prefrontal cortex, relatively little is known, especially with regard to calretinin, about the specific classes or distribution of local circuit neurons that contain these calcium-binding proteins. In this study, we used immunohistochemical techniques to characterize and compare the morphological features and distribution in macaque monkey prefrontal cortex of local circuit neurons that contain each of these calcium-binding proteins. On the basis of the axonal features of the labeled neurons, and correlations with previous Golgi studies, calretinin appeared to be present in double-bouquet neurons, calbindin in neurogliaform neurons and Martinotti cells, and parvalbumin in chandelier and wide arbor (basket) neurons. Calretinin was also found in other cell populations, such as a distinctive group of large neurons in the infragranular layers, but it was not possible to assign these neurons to a known cell class. In addition, although the animals studied were adults, immunoreactivity for both calretinin and calbindin was found in Cajal-Retzius neurons of layer I. Dual labeling studies confirmed that with the exception of the Cajal-Retzius neurons, each calcium-binding protein was expressed in separate populations of prefrontal cortical neurons. Comparisons of the laminar distributions of the labeled neurons also indicated that these calcium-binding proteins were segregated into discrete neuronal populations. Calretinin-positive neurons were present in greatest density in deep layer I and layer II, calbindin-immunoreactive cells were most dense in layers II-superficial III, and parvalbumin-containing neurons were present in greatest density in the middle cortical layers. In addition, the relative density of calretinin-labeled neurons was approximately twice that of the calbindin- and parvalbumin-positive neurons. However, within each group of labeled neurons, their laminar distribution and relative density did not differ substantially across regions of the prefrontal cortex. These findings demonstrate that calretinin, calbindin, and parvalbumin are markers of separate populations of local circuit neurons in monkey prefrontal cortex, and that they may be useful tools in unraveling the intrinsic inhibitory circuitry of the primate prefrontal cortex in but normal and disease states.

Animals↗
PubMed1995

Differential distribution of six calcium-binding proteins in the rat olfactory epithelium during postnatal development and adulthood.

Odorant stimulation of receptor cells results in a calcium influx that activates the transduction pathway. Ca2+ acceptors, such as calmodulin, may mediate between the change in intracellular calcium and the conductance mechanism underlying the initial electrical event. Ca2+ acceptors also may participate in subsequent processing of olfactory information. The identification and characterization of these molecules, therefore, should provide important information about the complex signal transduction pathway involving calcium in olfaction as well as other sensory systems. The present study describes the distribution of six calcium-binding proteins in the rat main olfactory epithelium during postnatal development to determine when different Ca2+ acceptors can be detected and whether they segregate into different layers or portions of the epithelium. Calmodulin, calretinin, calbindin-D28k, neurocalcin, and recoverin were detected immunohistochemically in olfactory receptors but not in basal cells. S-100 immunoreactivity was restricted to glial cells primarily around the cribriform plate. During postnatal development (from P1 to P20), calmodulin, calretinin, calbindin-D28k, and neurocalcin formed a gradient of immunoreactivity descending from the central to the lateral areas in the nasal cavity, whereas recoverin was expressed only in sporadic, mature receptors in the proximal region of the mucosa. At P20, the immunoreactivity pattern for each calcium-binding protein was identical to the adult profile, indicating that the olfactory epithelium had reached maturity by this stage. Olfactory nerve fiber bundles displayed a differential staining pattern from P1 until adulthood for calbindin-D28k and calretinin (internal portions of bundles). Differential calmodulin immunoreactivity of olfactory nerves (large external portions of bundles) appeared at P10. The immunoreactivity of the nerve fiber bundles may reflect a further degree of organization relevant to odor discrimination.

Animals↗
PubMed1995

Cajal-Retzius neurons in human cerebral cortex at midgestation show immunoreactivity for neurofilament and calcium-binding proteins.

Along with subplate neurons, Cajal-Retzius cells (CRc) are the first neurons to be generated in the cortical anlage. Studies of their chemical content, such as neurofilament and calcium-binding proteins, might give indications on their role in cortical development at midgestation in human fetuses (20-24 gestation weeks), when the CRc are morphologically mature. Cajal-Retzius cells were immunolabeled with antibodies to subunits of neurofilament proteins SMI31 and SMI32. The SMI32 antibodies (directed against the nonphosphorylated epitope) specifically labeled the CR cell bodies, dendrites, and proximal axons in a Golgilike fashion. Specific acetylcholinesterase activity is known to be typical of all the CRc, and double labeling for SMI32 immunoreactivity and acetylcholinesterase histochemistry demonstrated that all the CRc exhibited SMI32 immunoreactivity. The SMI31 antibodies (directed against the phosphorylated epitope) exclusively labeled the CRc axons, forming a dense positive network in the deep one-half of layer 1. This plexus was much denser than the one described with the Golgi method (Marin-Padilla, 1990: J. Comp Neurol 239:89-105). Calbindin D28k, parvalbumin, and calretinin immunoreactivities were visualized in the CRc. Double-labeling experiments showed that most of the CRc contained both calbindin and calretinin and sometimes parvalbumin. These colocalizations revealed a chemical heterogeneity within the CRc population even though they were described as morphologically homogeneous. These colocalizations of calcium-binding proteins in the CRc differed from the other nonpyramidal cortical neurons where calbindin, calretinin, and parvalbumin are contained in different (mutually exclusive) neuronal populations. Based on the morphological features and differential chemical contents described for the CRc, different hypotheses on their possible role and fate are discussed.

Acetylcholinesterase↗
PubMed2003

Reelin-expressing neurons in the postnatal and adult human hippocampal formation.

Reelin plays a major role in the development of laminated brain structures. In the developing neocortex and hippocampus, Reelin is secreted by Cajal-Retzius cells in the marginal zone. In the present report, we characterize Reelin-immunoreactive neurons in the perinatal and adult human hippocampal formation. Two main populations of cells are described: Cajal-Retzius cells and interneurons. Cajal-Retzius cells are defined as neurons that coexpress Reelin and p73, a nuclear protein of the p53 family. Colocalization experiments of p73 with calcium-binding proteins indicate that most Cajal-Retzius cells express calretinin, but not calbindin. Cajal-Retzius cell density decreases dramatically during the postnatal period, although a few Reelin/p73-positive neurons are still found in the adult. At birth, Reelin-positive, p73-negative neurons are present in all layers of the hippocampal formation. Their morphology and localization indicate that they belong to a heterogeneous population of interneurons. They are numerous in the strata lacunosum-moleculare and radiatum of CA1-CA3, in the hilus, and in the molecular layer of the dentate gyrus, but less common in stratum oriens and alveus, and rare in the principal cell layers. Subpopulations of Reelin-positive interneurons express calretinin or calbindin. The packing density of Reelin-positive cells decreases postnatally, which may be related to the disappearance of Cajal-Retzius cells and to the growth of the hippocampal formation. The presence of Reelin-immunoreactive cells in the adult hippocampal formation indicates that Reelin is not restricted to development but that it may have additional functions in adult life.

Adolescent↗
PubMed2002

Early induction of secretoneurin expression following kainic acid administration at convulsant doses in the rat and gerbil hippocampus.

The expression of secretogranin-II and its major proteolytic product secretoneurin (SN) is under the control of neuronal excitation, as demonstrated by treating rats with the excitotoxic kainic acid (KA). Differences in the structure and function of the hippocampus in rats and gerbils have been described; these suggest possible differential reactive responses to KA. In the present study, the SN immunostaining pattern in relation with cell damage is analyzed from 6 h to 4 days following KA administration in rats and gerbils. Dramatic differences in the expression of SN were found in the hippocampal complex following KA administration in gerbils and rats. A robust increase in SN immunoreactivity was detected in the pyramidal cell layer of the rat hippocampus, especially in the CA1 area. In the gerbil, however, a strong increase in SN immunostaining was detected in interneurons of the hippocampal formation, as shown by double-labeling immunohistochemistry to SN and the calcium-binding proteins parvalbumin, calbindin, and calretinin. In addition, no damage (in the hippocampal formation) or moderate damage (in the entorhinal cortex) was observed in the gerbil, in contrast to the rat. The administration of KA and the GABA-B receptor inhibitors (CGP56999A or CGP36742) to the gerbil resulted in a strong rise in SN immunoreactitivty in the CA1 pyramidal cell layer of the hippocampus, as in the rat. However, no increased cell damage was observed under these conditions. The present data provide evidence of a species-differential reactive response to KA that might be based, in part, on distinct inhibitory intrahippocampal circuitry.

Animals↗
PubMed2004

Calbindin D28k, parvalbumin, and calretinin immunoreactivity in the main and accessory olfactory bulbs of the gray short-tailed opossum, Monodelphis domestica.

The vertebrate main and accessory olfactory bulbs (MOB and AOB) are the first synaptic sites in the olfactory pathways. The MOB is a cortical structure phylogenetically well conserved in its laminar structure and overall synaptic organization, while the AOB has significant species variation in size. In order to better understand signal processing in the two olfactory systems and the species differences, immunocytochemical staining and analysis were done of the neuronal expression patterns of the calcium-binding proteins calbindin D28k (CB), parvalbumin (PV), and calretinin (CR) in the MOB and AOB in a marsupial species, the gray short-tailed opossum, Monodelphis domestica. In the MOB, antibody to CB labeled periglomerular cells, superficial short axon cells / Van Gehuchten cells; antibody to PV labeled Van Gehuchten cells; and antibody to CR immunostained periglomerular cells, superficial short axon cells / Van Gehuchten cells, and granule cells. In the AOB, CB immunoreactivity was detected in periglomerular cells and a subpopulation of granule cells; antibody to PV labeled the superficial short axon cells / Van Gehuchten cells and granule cells; and antibody to CR labeled a small number of periglomerular cells, superficial short axon cells / Van Gehuchten cells, and granule cells. These results showed that the patterns of CB, PV, and CR expression differ in the opossum main and accessory olfactory bulbs and differ from that in other animal species. These varying patterns of neuronal immunostaining may be related to the different functions of the main and accessory olfactory bulbs and to the differing signal processing features.

Animals↗
PubMed2006

Reorganization of CA3 area of the mouse hippocampus after pilocarpine induced temporal lobe epilepsy with special reference to the CA3-septum pathway.

We showed that when CA3 pyramidal neurons in the caudal 80% of the dorsal hippocampus had almost disappeared completely, the efferent pathway of CA3 was rarely detectable. We used the mouse pilocarpine model of temporal lobe epilepsy (TLE), and injected iontophoretically the anterograde tracer phaseolus vulgaris leucoagglutinin (PHA-L) into gliotic CA3, medial septum and the nucleus of diagonal band of Broca, median raphe, and lateral supramammillary nuclei, or the retrograde tracer cholera toxin B subunit (CTB) into gliotic CA3 area of hippocampus. In the afferent pathway, the number of neurons projecting to CA3 from medial septum and the nucleus of diagonal band of Broca, median raphe, and lateral supramammillary nuclei increased significantly. In the hippocampus, where CA3 pyramidal neurons were partially lost, calbindin, calretinin, parvalbumin immunopositive back-projection neurons from CA1-CA3 area were observed. Sprouting of Schaffer collaterals with increased number of large boutons in both sides of CA1 area, particularly in the stratum pyramidale, was found. When CA3 pyramidal neurons in caudal 80% of the dorsal hippocampus have almost disappeared completely, surviving CA3 neurons in the rostral 20% of the dorsal hippocampus may play an important role in transmitting hyperactivity of granule cells to surviving CA1 neurons or to dorsal part of the lateral septum. We concluded that reorganization of CA3 area with its downstream or upstream nuclei may be involved in the occurrence of epilepsy.

Animals↗