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PubMed1990

Immunocytochemical evidence for inhibitory and disinhibitory circuits in the superior olive.

Immunostaining of the cat superior olivary complex with antisera against glycine, calbindin, GABA, and its synthetic enzyme, glutamate decarboxylase (GAD) reveals considerable new information about neural connections that underlie processing of binaural signals. Antisera against glycine and calbindin immunostain principal cells and processes of the medial nucleus of the trapezoid body (MNTB). The extent of staining of fine processes afforded by the calbindin antisera reveals collateral processes of MNTB axons within the medial superior olive (MSO) and numerous terminals of these collaterals on neuronal somata and proximal dendrites. Electron microscopic immunocytochemistry of these terminals shows them to have the morphological features characteristic of inhibitory synapses, indicating that there can be considerable inhibitory inputs to MSO cells from the contralateral cochlear nucleus via the MNTB. Immunostaining for GAD and GABA shows some GABAergic inputs, mostly to dendrites within the MSO. Within the MNTB there are elaborate GABAergic endings that surround the principal cells. Electron microscopic immunocytochemistry of these terminals reveals the expected features characteristic of inhibitory synapses. The glycinergic inhibitory output of the MNTB cells is therefore subject to disinhibition by activity of these elaborate GABAergic inputs. Other endings that immunostain with antisera to leucine- enkephalin and neurotensin are found in modest amounts in both MSO and MNTB. Immunostaining of neuronal somata within the superior olivary complex suggests that the origins of the peptidergic and GABAergic endings in the MSO and MNTB may be periolivary cells. Whatever the origins, the results clearly indicate that control of the inhibitory GABAergic inputs to the MNTB can profoundly affect the inhibitory glycinergic MNTB outputs to other principal olivary nuclei. Investigations of the circumstances under which these circuits are activated will reveal much about neural processing that underlies binaural hearing.

Animals↗
PubMed1994

Horizontal cells in the rabbit retina: differentiation of subtypes at neonatal and postnatal stages.

We are investigating the differentiation of the major subtypes of horizontal cell in the rabbit retina in order to learn more about developmental controls responsible for the variety of neuronal phenotypes. Immunohistochemistry with anti-neurofilament and anti-calbindin-D antibodies, followed by epoxy resin embedding, has facilitated study of these neurons. In the mature rabbit retina, axonless (A-type) horizontal cells reacted strongly in procedures using either antibody; short axon (B-type) somas did not show a reaction with anti-neurofilament antibodies and stained moderately using anti-calbindin antibodies. In the immature neonatal retina the somas of all the horizontal cells seemed to be similar with regard to general morphology, but two populations could be distinguished on the basis of immunostaining. Some, identified as A-type horizontal cells (by comparison with mature retina), were stained using either antibody. Interspersed among these were similar cells with no detectable immunoreactivity, identified as B-type horizontal cells. By the end of the first postnatal week, faint reactivity to anti-calbindin-D was present in the somas of B-type horizontal cells; they stained moderately throughout the rest of the period studied. Thus differences in immunostaining indicate that the two horizontal cell subpopulations are established early in the rabbit, though some other distinguishing characteristics emerge only gradually as the retina matures. These results suggest that in mammals the determination of phenotypic subtype occurs early, possibly at the time that the cell is specified as a horizontal neuron, or shortly thereafter.

Animals↗
PubMed2004

Effect of mCOUP-TF1 deficiency on the glossopharyngeal and vagal sensory ganglia.

Immunohistochemistry for calcitonin gene-related peptide (CGRP), tyrosine hydroxylase and calbindin D-28k was performed on the glossopharyngeal and vagal ganglia in mCOUP-TFI knockout mice to know the effect of its deficiency on different types of primary sensory neurons. In wild type and heterozygous mice, the glossopharyngeal and vagal ganglia contained abundant CGRP-, tyrosine hydroxylase- and calbindin D-28k-immunoreactive (IR) neurons. In the ganglia of mCOUP-TFI knockout mice, a 38% decrease of CGRP-IR neurons was detected. However, the number of tyrosine hydroxylase- or calbindin D-28k-neurons was not altered by the mCOUP-TFI deficiency. In the tongue of knockout mice, the number of CGRP-IR nerve fibers decreased compared to wild-type and heterozygous mice. The development of CGRP-IR petrosal neurons, which supply innervation of the tongue, may depend on mCOUP-TFI.

Animals↗
PubMed2006

Neurochemical diversity of neurogliaform cells in the human primary motor cortex.

Neurogliaform cells of area 4 of the human motor cortex were found to express choline acetyl transferase (ChAT), gamma-aminobutyric acid, and calbindin. GABA- and calbindin-positive NGCs were mainly localized in layers II and VI and were relatively rare in layer I of the cortex. ChAT-positive NGCs were observed in the upper and middle thirds of layer II, occurring occasionally in layer I and the upper portion of layer III. Their numbers were low compared to those of GABA- and calbindin-positive NGCs in layers II/III. The dendrites of ChAT-positive NGCs were short and few in number. Axonal arborizations of neighboring ChAT-positive cells interpenetrated considerably so that each ChAT-positive cell body was normally surrounded by axonal trees of the parent and a few other ChAT-positive NGCs. NGC axon collaterals surrounded small neuropil areas containing perikarya presumptive pyramidal neurons. The findings are discussed in the context of information processing in cortical modules and interaction of excitatory and inhibitory interneurons.

Acetylcholine↗
PubMed2004

Dual enhancement of triple immunofluorescence using two antibodies from the same species.

Triple immunofluorescence method with two mouse monoclonal antibodies and another rabbit polyclonal antibody was established with catalyzed reporter deposition (CARD) amplification on thick floating sections from the rat cerebellum. One of the monoclonal antibodies (anti-calbindin), diluted maximally, probed with anti-mouse IgG-horseradish peroxidase (HRP) and amplified with Cy5-conjugated tyramide, immunolabeled cerebellar Purkinje cells and their arborization. Subsequently, a rabbit polyclonal IgG (anti-glial fibrillary acidic protein (anti-GFAP)), probed with anti-rabbit IgG-HRP, amplified with biotin-tyramide and visualized with fluorescein-isothiocyanate (FITC)-streptavidin, immunolabeled Bergmann's glia. Another mouse monoclonal IgG (anti-SNAP25), probed with anti-mouse IgG-rhodamine without CARD amplification, selectively visualized synaptic sites, because the maximal dilution of the other monoclonal antibody (anti-calbindin) was below the detection threshold of this anti-mouse IgG-rhodamine. Separation of the two signals (calbindin and SNAP25), each detected through mouse monoclonal antibody, was then based on the difference of sensitivity either with or without CARD amplification. Triple immunofluorescence is possible when just one of the three primary antibodies is from different species. Intensification of two of the three signals provides further advantages to examine immunolocalization of multiple epitopes on histological sections.

Animals↗
PubMed2006

A three-dimensional, histological and deformable atlas of the human basal ganglia. I. Atlas construction based on immunohistochemical and MRI data.

This paper describes the construction of an atlas of the human basal ganglia. The successive steps of the construction were as follows. First a postmortem specimen was subjected to a MRI acquisition prior to extraction of the brain from the skull. The brain was then cryosectioned (70 microm thickness). One section out of ten (80 sections) was Nissl-stained with cresyl violet, another series of 80 sections was immunostained for the calcium binding protein calbindin. Contours of basal ganglia nuclei including their calbindin-stained functional subdivisions, fiber bundles and ventricles (n=80 structures) were traced from histological sections and digitized. A novelty of this atlas is the MRI acquisition, which represents the core data element of the study. MRI was used for the coregistration of the atlas data and permitted, through multimodal (Nissl, calbindin, images of cryosectioning, T1 and T2 MRI) and 3D optimization, the production of anatomically and geometrically consistent 3D surfaces, which can be sliced through any desired orientation. The atlas MRI is also used for its deformation to provide accurate conformation to the MRI of living patients, thus adding information at the histological level to the patient's MRI volume. This latter aspect will be presented in a forthcoming paper.

Basal Ganglia↗
PubMed2000

Distinct signaling pathways involved in multiple effects of basic fibroblast growth factor on cultured rat hippocampal neurons.

We investigated possible involvement of voltage-dependent Ca(2+) channels (VDCCs) and several intracellular signaling mechanisms in multiple actions of basic fibroblast growth factor (bFGF), such as survival promotion, induction of calbindin D(28k) expression as well as acceleration of neuritic branch formation of cultured rat hippocampal neurons. Immunocytochemical staining with anti-gamma-aminobutyric acid (GABA) antibody showed that the promotion of neuron survival by bFGF in high cell-density cultures were exerted exclusively on GABA-negative neurons. Nicardipine (5 microM) attenuated the effect of bFGF on neuronal survival and formation of neurite branches, suggesting that the activity of L-type VDCCs is required for these effects. In contrast, stimulation of calbindin expression by bFGF was not attenuated by nicardipine. A phospholipase C inhibitor U73122 (1 microM) prevented the effect of bFGF on neurite branch formation, but not on neuronal survival or calbindin expression. On the other hand, chronic application of phorbol-12-myristate-13-acetate (1 microM) inhibited the effect of bFGF on neuronal survival, without inhibiting the other bFGF actions. Forskolin (100 microM) attenuated the effect of bFGF on neuronal survival and neurite branch formation, indicating that cyclic AMP plays negative regulatory roles in these actions of bFGF. Taken together, these results suggest that multiple biological actions of bFGF on hippocampal neurons are exerted through, and modulated by, distinct signaling pathways.

Animals↗
PubMed1997

Subcellular localization of the K+ channel subunit Kv3.1b in selected rat CNS neurons.

Voltage-gated potassium channels constitute the largest group of heteromeric ion channels discovered to date. Over 20 genes have been isolated, encoding different channel subunit proteins which form functional tetrameric K+ channels. We have analyzed the subcellular localization of subunit Kv3.1b, a member of the Kv3 (Shaw-like) subfamily, in rat brain at the light and electron microscopic level, using immunocytochemical detection. Detailed localization was carried out in specific neurons of the neocortex, hippocampus and cerebellum. The identity of Kv3.1b-positive neurons was established using double labeling with markers for specific neuronal populations. In the neocortex, the Kv3.1b subunit was expressed in most parvalbumin-containing bipolar, basket or chandelier cells, and in some bipolar or double bouquet neurons containing calbindin. In the hippocampus, Kv3.1b was expressed in many parvalbumin-containing basket cells, as well as in calbindin-positive neurons in the stratum oriens, and in a small number of interneurons that did not stain for either parvalbumin or calbindin. Kv3.1b protein was not present in pyramidal cells in the neocortex and the hippocampus, but these cells were outlined by labeled presynaptic terminals from interneuron axons that surround the postsynaptic cell. In the cerebellar cortex, granule cells were the only population expressing the channel protein. Careful examination of individual granule cells revealed a non-uniform distribution of Kv3.1 staining on the somata: circular bands of labeling were present in the vicinity of the axon hillock. In cortical and hippocampal interneurons, as well as in cerebellar granule cells, the Kv3.1b subunit was present in somatic and unmyelinated axonal membranes and adjacent cytoplasm, as well as in the most proximal portion of dendritic processes, but not throughout most of the dendrite. Labeling was also seen in the terminals of labeled axons, but not at a higher concentration than in other parts of the axon. The distribution in the cells analyzed supports a role in action potential transmission by regulating action potential duration.

Animals↗
PubMed2002

Newly identified endometrial genes of importance for implantation.

The mammalian uterus is normally not receptive to embryo implantation except during the very limited 'window of implantation'. To identify genes that may be responsible for this phenomenon the technique of RNA differential display (DD-PCR) was applied to implantation and inter-implantation sites on day 4.5 of pregnancy in the mouse, the time at which the blastocyst becomes attached to the endometrium. Three of these genes were identified as splicing factor SC35, calbindin-D9k and monoclonal non-specific suppressor factor beta (MNSFbeta). Expression of SC35 mRNA, which is responsible for removal of introns from pre-mRNA, is much higher in implantation than in interimplantation sites during pregnancy. Expression of alternatively spliced mRNAs for SC35 is differentially regulated by early pregnancy and steroid hormones. By contrast, calbindin-D9k, a regulator of calcium, is upregulated by progesterone and its mRNA increases in the uterus during early pregnancy compared with during the cycle, although it is significantly lower in implantation sites than in interimplantation sites on days 4.5-5.5 of pregnancy, but subsequently becomes barely detectable in both sites. The mRNA for calbindin-D9k is predominantly in endometrial luminal epithelium. MNSFbeta, a cytokine involved in regulation of the immune system, showed lower expression at implantation sites than interimplantation sites on day 4.5 of pregnancy, when embryos first attach to the uterus and initiate implantation, and on day 5.5 when implantation has advanced. Immunohistochemically, the protein was localized to endometrial stromal cells in the non-pregnant uterus, but disappeared as decidualization progressed. The precise roles of these three proteins in the process of embryo implantation remains to be determined. Homologues of the proteins may contribute to the development of the 'window of implantation' in the human and hence be appropriate targets for new post-coital contraceptives or may be manipulated to improve fertility.

Animals↗
PubMed2000

Neurturin protects striatal projection neurons but not interneurons in a rat model of Huntington's disease.

Glial cell line-derived neurotrophic factor and neurturin are neurotrophic factors expressed in the striatum during development and in the adult rat. Both molecules act as target-derived neurotrophic factors for nigrostriatal dopaminergic neurons. While glial cell line-derived neurotrophic factor has also been described to have local trophic effects on striatal neurons, the effects of neurturin in the striatum have not yet been described. Here we examine whether neurturin protects striatal projection neurons (calbindin-positive) and interneurons (parvalbumin- or choline acetyltransferase-positive) in an animal model of Huntington's disease. A fibroblast cell line engineered to over-express neurturin was grafted into adult rat striatum 24h before quinolinate injection. In animals grafted with a control cell line, intrastriatal quinolinate injection reduced the number of calbindin-, parvalbumin- and choline acetyltransferase-positive neurons, seven days post-lesion. Intrastriatal grafting of neurturin-secreting cells protected striatal projection neurons, but not interneurons, from quinolinate excitotoxicity. This effect was much more robust than that reported previously for a glial cell line-derived neurotrophic factor-secreting cell line on striatal calbindin-positive neurons. However, intrastriatal grafting of glial cell line-derived neurotrophic factor- but not neurturin-secreting cells prevented the decrease in choline acetyltransferase activity induced by quinolinate injection. Taken together, our results show that neurturin- and glial cell line-derived neurotrophic factor-secreting cell lines have clearly differential effects on striatal neurons. Grafting of the neurturin-secreting cell line showed a more specific and efficient trophic effect on striatal projection neurons, the neuronal population most affected in Huntington's disease. Therefore, our results suggest that neurturin is a good candidate for the treatment of this neurodegenerative disorder.

Animals↗
PubMed1998

Calcium-binding protein immunoreactivity in the piriform cortex of the guinea-pig: selective staining of subsets of non-GABAergic neurons by calretinin.

Selective immunostaining for calcium-binding proteins identifies subpopulations of neurons with hypothetical distinct functional roles. The neuronal localization of calcium-binding proteins calretinin, parvalbumin and calbindin is here correlated to GABA and glutamate immunoreactivity in the guinea-pig piriform cortex. In the external border of the molecular layer, neurons positive for calretinin with morphological features of Cajal-Retzius cells were found. Rare GABA immunoreactive cells were observed in the same subpial region, whereas neurons containing GABA were abundant within layers Ia and Ib. Aspartate- and glutamate-immunoreactive cells were also found in the outer Ia layer. A distinct band of calretinin-immunoreactive fibres and terminals localized in layer Ia, where the afferent fibres originating from the olfactory bulb are segregated. In layer II the number of cells containing calretinin exceeded the number of neurons positive for the anti-GABA antibody. Part of the layer II calretinin-positive neurons with pyramidal shape and large apical dendrites directed toward the surface were found to be immunoreactive for the anti-glutamate antibody on adjacent sections. Neurons in layer II immunoreactive for either parvalbumin or calbindin showed morphological features of interneurons, and their number matched the count of GABA containing cells. Calretinin-positive neurons with the general morphological features of interneurons were scarcely represented in the deep piriform cortical layers, where large multipolar and small bipolar calbindin-positive cells prevailed. The present data show that in the piriform cortex of the guinea-pig calretinin, although expressed in Cajal-Retzius-like cells as in other cortical areas, also marks a subpopulation of glutamate containing pyramidal-like neurons in layer II.

Animals↗
PubMed1998

Cytoarchitecture of the tectum opticum in the Japanese quail.

The cytoarchitecture of the optic tectum of the Japanese quail, Coturnix coturnix japonica, was studied using the Golgi-Kopsch method, parvalbumin, calbindin and GABA immunohistochemistry and nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry. Our results reveal a large number of different types of interneurons in the quail tectum opticum, only part of which are described in the chick or pigeon. Application of parvalbumin and calbindin immunohistochemistry and nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry reveals the following lamination pattern: The stratum opticum, stratum griseum centrale and stratum album centrale remain unstained, while the laminae of the stratum griseum et fibrosum superficiale exhibit a roughly complementary staining pattern of calbindin (laminae c, d, e, f, g, i) and parvalbumin (laminae a, h, i). Nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry yields a dense band in lamina i. The Golgi material reveals the following cell types in the stratum griseum et fibrosum superficiale: marginal cells in the stratum opticum and in lamina h and i, horizontal cells in laminae a and c, large and small radial cells in laminae b, d, h and i, multiform cells in lamina b, bitufted cells in lamina d and e, large pear-shaped cells in lamina g, wide-field cells in lamina j, and stellate cells in lamina j and in the stratum griseum centrale. We consider horizontal cells, bitufted cells, multiform cells and small radial cells to be GABAergic interneurons of the stratum griseum et fibrosum superficiale which seem to be more numerous than in the pigeon tectum opticum. Golgi impregnation and injection of Phaseolus vulgaris leucoagglutinin into the pretectal nucleus lentiformis yielded regularly distributed clusters of telodendra of pretectal axons in lamina d of the stratum griseum et fibrosum superficiale, which are identical in shape and position with axon plexus revealed by Golgi staining.

Animals↗
PubMed2000

Differences between rats and rabbits in NMDA receptor-mediated calcium signalling in hippocampal neurones.

In vivo microdialysis combined with the measurement of (45)Ca(2+) efflux from prelabelled hippocampus demonstrated a pronounced N-methyl-D-aspartate (NMDA)-evoked (45)Ca(2+) release to the dialysate in the rat dentate gyrus (DG) and CA1, whereas in rabbit a slight release of (45)Ca(2+) was observed only in the DG. In vitro, we noticed that the NMDA-evoked increase in Fura-2 detected intracellular Ca(2+) concentration in synaptoneurosomes from the rat, but not from the rabbit hippocampus, was strongly inhibited by the ryanodine receptor (RyR) antagonists dantrolene and ryanodine. To establish the mechanism of these differences, we characterised their possible dependence on the expression of RyR and their co-localisation with the calcium binding protein calbindin D(28k). A pronounced expression of [(3)H]ryanodine binding sites in the rat DG, which is only slight in the CA1, was demonstrated whereas in rabbit they were only found in the DG. The pattern of expression of calbindin D(28k) immunoreactivity and RyR in the rat and rabbit hippocampus was similar. These results suggest that the functional role of RyR in the generation of the NMDA receptor-mediated intracellular Ca(2+) signalling in the rabbit hippocampal neurones is marginal when compared to the rat. These differences reflect a diverse expression of RyR in both species. The corresponding differences in calbindin D(28k) immunoreactivity are most probably secondary in nature.

Animals↗
PubMed1995

Localization of the Ca(2+)-binding alpha-parvalbumin and its mRNA in epiphyseal plate cartilage and bone of growing rats.

This study describes the localization of alpha-parvalbumin, in undecalcified tibial epiphyseal cartilage and bone of growing rats by immunocytochemistry in the light microscope, and of parvalbumin mRNA by in situ hybridization. They were compared to the distribution of the calbindin-D9K and its mRNA in rat epiphyseal cartilage. All the chondrocytes of the epiphyseal cartilage were parvalbumin-immunopositive, but there was no parvalbumin immunoreactivity in the uncalcified or calcified extracellular cartilage matrix. The intensity of the immunostaining increased from the resting and proliferative to the mature and hypertrophic chondrocytes, with the greatest intensity in the terminal hypertrophic chondrocytes in the calcifying zone. The parvalbumin immunostaining was located in the cytoplasm, but no immunoreactivity was detected in any chondrocyte processes. The parvalbumin mRNA distribution and levels, as revealed by in situ hybridization, exactly mirrored those of the parvalbumin protein. In contrast to parvalbumin, calbindin-D9K and its mRNA appeared in mature chondrocytes and decreased in hypertrophic up to calcifying chondrocytes. Calbindin-D9K was located in the cytoplasm and all along the cell processes. In bone, the osteoblasts and the osteocytes of trabecular and compact cortical bones were immunoreactive for parvalbumin and contained parvalbumin mRNA. Parvalbumin lay in their cytoplasm, but there was no parvalbumin immunostaining in the extracellular uncalcified or mineralized bone matrix. The long processes of osteocytes, in compact bone only, were parvalbumin immunoreactive. Osteoclasts contained cytoplasmic parvalbumin immunoreactivity. Thus, the pattern of immunoreactive parvalbumin distribution indicates that the protein is not involved in the extracellular mineralization of cartilage and bone matrix. It appears to be associated with specific calcium-related intracellular functions in chondrocytes and in osteoblasts, osteocytes, and osteoclasts. As the highest cytoplasmic concentration of parvalbumin is in the terminal hypertrophic chondrocytes, parvalbumin could act as a calcium buffer to delay the death of chondrocytes. In compact bone, parvalbumin could also have a role throughout the osteocyte processes in regulating the fluxes of calcium ions for mineral homeostatis.

Animals↗
PubMedDate not supplied

Morphological types of horizontal cell in rodent retinae: a comparison of rat, mouse, gerbil, and guinea pig.

Retinal horizontal cells of four rodent species, rat, mouse, gerbil, and guinea pig were examined to determine whether they conform to the basic pattern of two horizontal cell types found in other mammalian orders. Intracellular injections of Lucifer-Yellow were made to reveal the morphologies of individual cells. Immunocytochemistry with antisera against the calcium-binding proteins calbindin D-28k and parvalbumin was used to assess population densities and mosaics. Lucifer-Yellow injections showed axonless A-type and axon-bearing B-type horizontal cells in guinea pig, but revealed only B-type cells in rat and gerbil retinae. Calbindin immunocytochemistry labeled the A- and B-type populations in guinea pig, but only a homogeneous regular mosaic of cells with B-type features in rat, mouse, and gerbil. All calbindin-immunoreactive horizontal cells in the latter species were also parvalbumin-immunoreactive; comparison with Nissl-stained retinae showed that both antisera label all of the horizontal cells. Taken together, the data from cell injections and the population studies provide strong evidence that rat, mouse, and gerbil retinae have only one type of horizontal cell, the axon-bearing B-type, whereas the guinea pig has both A- and B-type cells. Thus, at least three members of the family Muridae differ from other rodents and deviate from the proposed mammalian scheme of horizontal cell types. The absence of A-type cells is apparently not linked to any peculiarities in the photoreceptor populations, and there is no consistent match between the topographic distributions of the horizontal cells and those of the cone photoreceptors or ganglion cells across the four rodent species. However, the cone to horizontal cell ratio is rather similar in the species with and without A-type cells.

Animals↗
PubMedDate not supplied

Synaptic inputs of class III and class V interneurons in the cat pulvinar nucleus: differential integration of RS and RL inputs.

We previously reported that two types of visual thalamic interneurons (class III and class V) could be distinguished by the presence or absence of the enzyme brain nitric oxide synthase (bNOS; Bickford et al., 1999). In the present study, we found that further immunocytochemical characterization can be used to isolate class V and class III neurons: class V neurons express GABA and bNOS but not the calcium binding protein calbindin, whereas class III neurons express GABA and calbindin, but not bNOS. By pairing staining for bNOS or calbindin with staining for GABA, we were able to distinguish class III and class V neurons, thereby allowing us to characterize the synaptic inputs to these two interneuron populations within the cat pulvinar nucleus. We found class III and class V interneurons participate in distinctly different circuitries. Class III cells receive the majority of their input from large terminals with round vesicles (RL profiles, that presumably originate from cortical layer V) while class V cells receive all of their input from small terminals with round vesicles (RS profiles, that presumably originate from cortical layer VI). These two types of interneurons also target different regions of the dendritic arbors of thalamocortical cells; class III cells contact large caliber (presumably proximal) thalamocortical dendrites within glomeruli, while class V cells contact the small caliber (presumably distal) thalamocortical cell dendrites within the extraglomerular neuropil. Thus, a dual inhibitory system exists within the visual thalamus that integrates different types of corticothalamic input and targets distinct regions of thalamocortical cell dendritic arbors.

Animals↗
PubMed1999

Expression of genes involved in calcium absorption in human duodenum.

BACKGROUND: The role of vitamin D metabolites in the regulation of expression of genes involved in dietary calcium absorption by the human intestine remains poorly understood despite much work in animals. MATERIALS AND METHODS: To investigate this, we measured the expression of transcripts for two of these genes, calbindin-D9k and the basolateral membrane calcium pumping ATPase, PMCA1, in duodenal endoscopic biopsies from 40 subjects. Northern blots were hybridized with previously characterized probes, and the signal was quantified by phosphor imaging. These transcript levels were related to circulating vitamin D metabolites and also analysed according to the vitamin D receptor gene TaqI polymorphism determined in DNA from blood. RESULTS: Plasma 1,25-dihydroxycholecalciferol correlated significantly with calbindin-D9k RNA (r = 0.4, P < 0.02) but not with PMCA1. Plasma 25-OH-cholecalciferol was not correlated with transcripts for either gene and, furthermore, the mean levels of these transcripts did not differ significantly when grouped by vitamin D receptor genotype. CONCLUSION: In normal humans, 1, 25-dihydroxycholecalciferol has a small but significant relationship to duodenal expression of calbindin-D9k, but not to PMCA1 expression.

Calbindins↗
PubMed1996

Characterization of the responses of Purkinje cells to neurotrophin treatment.

The ability of the neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5) to promote neuronal survival and phenotypic differentiation was examined in dissociated cultures from embryonic day 16 rat cerebellum. BDNF treatment increased the survival of neuron-specific enolase-immunopositve cells by 250 and 400% after 8 and 10 days in culture, respectively. A subpopulation of these neurons, the Purkinje cells, identified by calbindin staining, was increased to an equivalent extent, approximately 200%, following BDNF, NT-4/5 or NT-3 treatment. The number of GABAergic neurons, identified by GABA immunoreactivity, was greatly increased by treatment with BDNF (470%) and moderately by NT-4/5 (46%), whereas NT-3 was without effect. NGF failed to increase the number of either Purkinje cells or GABAergic neurons. Addition of BDNF within 48 h of cell plating was required to obtain a maximal increase in Purkinje cell number after 8 days. In contrast, the NT-3 responses were nearly equivalent even if treatment was delayed for 96 h after plating. BDNF, NT-4/5, and NT-3, but not NGF, induced the rapid expression of the immediate early gene c-fos. Immunocytochemical double-labeling with antibodies to c-fos and calbindin was used to identify Purkinje cells that responded to neurotrophin treatment by induction of c-fos. After 4 days in vitro, both BDNF and NT-3 induced the formation of c-fos protein in calbindin-immunopositive neurons, whereas NT-4/5 did not. The latter results suggest that although BDNF and NT-4/5 have been shown to act through a common receptor, TrkB, it appears that the effects of BDNF and NT4/5 are not identical.

Animals↗