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PubMed2002

Effect of Brn-3a deficiency on parvalbumin-, calbindin D-28k-, calretinin- and calcitonin gene-related peptide-immunoreactive primary sensory neurons in the trigeminal ganglion.

Immunohistochemistry for parvalbumin, calbindin D-28k, calretinin and calcitonin gene-related peptide (CGRP) was performed on the trigeminal ganglion and oro-facial tissues in Brn-3a wildtype and knockout mice at embryonic day 18.5 and postnatal day 0. In wildtype mice, the trigeminal ganglion contained abundant parvalbumin-, calbindin D-28k- and CGRP-immunoreactive neurons while the ganglion was almost devoid of calretinin-immunoreactive neurons. In Brn-3a knockout mice, a 63% decrease of parvalbumin-immunoreactive neurons was detected. In contrast, the absence of Brn-3a dramatically increased the number of calbindin D-28k-immunoreactive (3.5-fold increase) and calretinin-immunoreactive neurons (91-fold increase). The number of CGRP-immunoreactive neurons, however, was not altered by the Brn-3a deficiency. Cell size analysis indicated that loss of Brn-3a increased the proportions of small (<100 microm (2)) parvalbumin-, calbindin D-28k- and CGRP-immunoreactive neurons while it decreased those of large (>200 microm(2)) immunoreactive cells. Calretinin-immunoreactive neurons were either small or medium (100-200 microm (2)) in mutant mice. The oro-facial tissues contained parvalbumin-, calbindin D-28k- and CGRP-immunoreactive fibers, but not calretinin-immunoreactive ones in wildtype mice. In Brn-3a knockout mice, the number of parvalbumin-immunoreactive fibers markedly decreased in the infraorbital nerve and parvalbumin-immunoreactive endings disappeared in the vibrissa. In contrast, the number of calbindin D-28k-immunoreactive fibers increased significantly in the infraorbital and mental nerves. In addition, calbindin D-28k-immunoreactive endings appeared in the vibrissa. As well, some fibers showed calretinin-immunoreactivity in the infraorbital nerve of the mutant. However, no obvious change of CGRP-immunoreactive fibers was observed in the oro-facial region of knockout mice. Taken together, our data suggest that Brn-3a deficiency has effects on the expression of neurochemical substances in the trigeminal ganglion.

Animals↗

PubMed1997

Loss of Calbindin-D28K immunoreactivity from dentate granule cells in human temporal lobe epilepsy.

The loss of the calcium binding protein, Calbindin-D28k, from dentate granule cells has been observed in different animal models of epilepsy and in ischaemia. This decrease is accompanied by alterations of calcium and N-methyl-D-aspartate currents, which may explain the hyperexcitability of the dentate gyrus. In the present study, we found a loss of calbindin immunoreactivity from over 90% of the dentate granule cells in lobectomy samples from four of 10 temporal lobe epilepsy patients. In another four patients, over 50%, of dentate granule cells were devoid of calbindin immunoreactivity, whereas the remaining two cases showed a 20-30% decrease. Electron microscopy revealed a normal ultrastructure both in calbindin-containing and calbindin-negative granule cells. Both calbindin-positive and -negative mossy fibre collaterals participated in supragranular sprouting. As inferred from data in animal models, the lack of calbindin in dentate granule cells of human epileptic subjects is likely to result in hyperexcitability of the dentate gyrus, which may then function as a "motor" for seizures.

Adolescent↗

PubMed1999

Inhibition of calcium-dependent NMDA receptor current rundown by calbindin-D28k.

NMDA receptors are regulated by several different calcium-dependent processes. To determine if the presence of the intracellular calcium-binding protein calbindin-D28k can influence the calcium regulation of NMDA receptor activity, human embryonic kidney 293 cells were co-transfected with cDNAs for NMDA receptor subunits and calbindin. Recordings were made using the nystatin perforated patch technique to preserve intracellular contents. When compared with control cells (transfected with cDNA encoding beta-galactosidase in place of calbindin), the presence of calbindin had no effect on either calcium-dependent inactivation or the calcium-sensitive, time-dependent increase in glycine-independent desensitization of NMDA receptor-mediated currents. However, the development of calcium-dependent rundown of peak glutamate-evoked current was slowed significantly in calbindin versus beta-galactosidase co-transfected cells. This result was true for cells transfected with either NR1/NR2A or NR1/NR2B subunits, although calbindin was relatively less effective at inhibiting rundown in NR1/NR2B-expressing cells. NMDA peak current rundown has been attributed to calcium-induced depolymerization of the actin cytoskeleton. Therefore, our results indicate that although calbindin may not influence calcium-dependent regulatory processes occurring very near the NMDA receptor channel, it appears to be more effective at buffering local elevations in intracellular calcium at the actin cytoskeleton.

Calbindin 1↗

PubMed2000

Opposite regulation of calbindin and calretinin expression by brain-derived neurotrophic factor in cortical neurons.

Regulation of calbindin and calretinin expression by brain-derived neurotrophic factor (BDNF) was examined in primary cultures of cortical neurons using immunocytochemistry and northern blot analysis. Here we report that regulation of calretinin expression by BDNF is in marked contrast to that of calbindin. Indeed, chronic exposure of cultured cortical neurons for 5 days to increasing concentrations of BDNF (0.1-10 ng/ml) resulted in a concentration-dependent decrease in the number of calretinin-positive neurons and a concentration-dependent increase in the number of calbindin-immunoreactive neurons. Consistent with the immunocytochemical analysis, BDNF reduced calretinin mRNA levels and up-regulated calbindin mRNA expression, providing evidence that modifications in gene expression accounted for the changes in the number of calretinin- and calbindin-containing neurons. Among other members of the neurotrophin family, neurotrophin-4 (NT-4), which also acts by activating tyrosine kinase TrkB receptors, exerted effects comparable to those of BDNF, whereas nerve growth factor (NGF) was ineffective. As for BDNF and NT-4, incubation of cortical neurons with neurotrophin-3 (NT-3) also led to a decrease in calretinin expression. However, in contrast to BDNF and NT-4, NT-3 did not affect calbindin expression. Double-labeling experiments evidenced that calretinin- and calbindin-containing neurons belong to distinct neuronal subpopulations, suggesting that BDNF and NT-4 exert opposite effects according to the neurochemical phenotype of the target cell.

Animals↗

PubMed1995

Stimulation of plasma membrane Ca2+ pump by calbindin-D28k and calmodulin is additive in EGTA-free solutions.

In enterocytes and erythrocytes a calmodulin-stimulated Ca(2+)-ATPase is the main Ca2+ efflux pathway. Previous studies have shown that in enterocytes this Ca(2+)-pumping ATPase could be stimulated by vitamin D-dependent Ca(2+)-binding protein, calbindin-D9k, in ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA)-free solutions. In contrast, a similar stimulatory effect of calbindin-D9K was not observed in erythrocytes. We reinvestigated the effects of calbindin, parvalbumin and calmodulin on active Ca2+ uptake in membrane vesicles derived from porcine erythrocytes and from rat duodenum. In EGTA-containing solutions, neither calbindin-D28k nor parvalbumin influenced the rate of ATP-dependent Ca2+ uptake in red blood cell-derived vesicles. However, when EGTA-free solutions were used, calbindin D28k and parvalbumin significantly increased ATP-dependent Ca2+ uptake in erythrocyte as well as in enterocyte-derived membrane vesicles. In contrast, calmodulin significantly increased active Ca2+ uptake in erythrocyte vesicles in the absence as well as in the presence of EGTA. In addition, ATP-dependent Ca2+ uptake in the presence of 0.2 microM calmodulin was further increased by parvalbumin in the absence but not in the presence of EGTA. This observation precludes that parvalbumin and calbindin stimulate the plasma membrane Ca(2+)-ATPase by occupying the calmodulin binding site. Our results support the theoretical notion that calbindin and parvalbumin stimulate the Ca(2+)-starved pump by increasing the free Ca2+ in the immediate vicinity of the Ca2+ pump sites.

Animals↗

PubMed2005

Overexpression of calbindin-D28K in hippocampal progenitor cells increases neuronal differentiation and neurite outgrowth.

Excitatory stimuli are known to be a potent regulator for induction of neuronal differentiation. Calbindin-D28K buffers intracellular Ca2+ and modifies synaptic functions in neurons. However, the effects of calbindin-D28K on the regulation of activity-induced neuronal differentiation and related biochemical modifications remain unsolved. In the present study, by a gain-of-function study with retroviral vector system and dicer-generated small interfering RNA (d-siRNA) to effectively knock down the expression of calbindin-D28K, we demonstrated that calbindin-D28K at a physiologically relevant level promoted neuronal differentiation and neurite outgrowth. Increase of neuronal differentiation by calbindin-D28K overexpression was concurrent with the expression of basic helix-loop-helix (bHLH) transcriptional factors, phosphorylation of calcium and calmodulin-dependent protein kinase II (CaMKII) and NeuroD at Ser(336). KN-62, a highly specific CaMKII inhibitor, blocked the up-regulation of proneural bHLH genes, p-CaMKII, and pSer(336)NeuroD. Calbindin-D28K appeared to facilitate neuronal differentiation of both fetal and adult hippocampal progenitor cells. Together, these findings establish the novel calbindin-regulated function of CaMKII and NeuroD in control of neuronal differentiation and neurite outgrowth.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1993

Chronic morphine increases calbindin D28k in rat striatum: possible NMDA receptor involvement.

The neuronal intracellular calcium-binding protein calbindin D28k is a neurochemical marker in the striatum, normally expressed in the matrix compartment and absent from the mu-opiate receptor-enriched striosomal (patch) compartment. Because chronic treatment with morphine has been reported to increase calcium levels in synaptosomes of rat striatum, we studied effects of morphine on calbindin immunoreactivity (ir) in rat brain, using immunocytochemistry. Treatment with morphine for 5 days increased calbindin-ir in the striatal matrix, and induced intense calbindin-ir in the patch compartment. Increased calbindin-ir in patches persisted through day 14 post-morphine. Co-administration of the NMDA receptor antagonist MK-801 blocked the morphine-induced increase in calbindin-ir in patches. We suggest that chronic morphine treatment may increase calcium and calbindin levels via increased glutamatergic transmission in striatum. These findings are consistent with reports that MK-801 inhibits tolerance to morphine, and provide a possible mechanism and anatomical substrate for this inhibition.

Animals↗

PubMed1995

Calbindin-D28k: role in determining intrinsically generated firing patterns in rat supraoptic neurones.

1. Physiological activation of rat supraoptic nucleus (SON) neurones leads to phasic firing in vasopressin neurones and fast, continuous firing in oxytocin neurones. Using whole-cell patch clamp methods in brain slices, we investigated the role of endogenous calbindin-D28k (calbindin) in determining these intrinsically generated patterns of firing. 2. Direct introduction of calbindin (0.1-0.2 mM) into twelve of twelve phasically firing neurones suppressed Ca(2+)-dependent depolarizing after-potentials (DAPs) and changed activity from phasic to continuous firing. Bovine calcium binding protein (0.3 mM), an analogue of calbindin, had similar effects on both DAPs and firing patterns in five of five cells tested. 3. Introduction of anti-calbindin antiserum (1:2000-5000) into thirteen of thirteen continuously firing neurones unmasked DAPs and converted continuous into phasic firing. Such effects could not be mimicked either by diffusion of normal rabbit serum or antibodies directed against glial fibrillary acidic protein or against neurophysin. 4. Immunocytochemical staining with antisera directed against calbindin revealed more intense staining in the dorsal, oxytocin-rich and less intense staining in the ventral, vasopressin-rich areas of the SON. 5. Elevated intracellular Ca2+ concentration ([Ca2+]i; 0.1 mM) induced DAPs and phasic firing in all twenty-nine SON cells recorded. During chelation of intracellular Ca2+ with (1.1-11 mM) BAPTA, fifty-eight of fifty-eight neurones recorded displayed regular continuous activity and had no DAPs. 6. These data suggest that firing activities in SON cells are dependent on [Ca2+]i and that calbindin, acting as an endogenous Ca2+ buffer, is involved in regulation of intrinsic firing patterns. It is likely that calcium binding proteins have a similar influence on the firing patterns of many neuronal types throughout the nervous system.

Action Potentials↗

PubMed1994

Novel immunohistochemical localization of 28,000 molecular-weight (Mr) calcium binding protein (calbindin-D28k) in enterochromaffin cells of the human appendix and neuroendocrine tumors (carcinoids and small-cell carcinomas) of the midgut and foregut.

Calbindin-D28k is a highly conserved 28,000 (dalton) molecular-weight (Mr) calcium binding protein with broad tissue distribution, yet cell-type-specific expression predominantly in subpopulations of central and peripheral nervous system neurons, distal tubular cells of the kidney, and enteric neuroendocrine cells. A polyclonal antiserum against rat renal calbindin-D28k and a monoclonal antibody to calbindin-D28k purified from chicken intestine (clone CL-300) were used for immunohistochemical evaluation of formalin-fixed, paraffin-embedded tissues from multiple areas of the human small and large intestines and 93 primary neoplasms of the gastrointestinal tract (foregut, midgut, and hindgut derivatives) and the lung (foregut derivative). Calbindin-D28k immunostaining was obtained in a minority of enterochromaffin (neuroendocrine) cells, predominantly of the appendix and small intestine, as well as in autonomic neurons of the neural plexuses. Focal cytoplasmic Golgi-type staining was obtained with monoclonal antibody CL-300 in the appendiceal surface epithelium and dendritic macrophages confined to the appendiceal lymphoid follicles. Epithelial progenitor cells in enteric crypts and absorptive, goblet, and Paneth cells were calbindin-D28k negative, while no immunoreactivity was demonstrated in the mucosae of the colon and rectum. Calbindin-D28k staining was consistently detected in subpopulations of neuroendocrine phenotypes in midgut (appendiceal/ileal) and foregut (bronchial) carcinoids and small-cell carcinomas, but was absent in adenocarcinomas, squamous cell carcinomas, leiomyomas/leiomyosarcomas, schwannomas, and lymphomas. Our observations suggest that calbindin-D28k is a novel adjuvant neuroendocrine marker that is potentially useful in diagnostic tumor immunohistochemistry.

Adult↗

PubMed1996

Chronic morphine decreases calbindin D28k immunoreactivity in a subset of cerebellar Purkinje neurons of rat brain.

Calbindin D28k is an intracellular calcium binding protein that is expressed in the cell bodies, nuclei, dendrites, and axons of nearly all Purkinje neurons of the rat cerebellum. Acute morphine administration has been reported to decrease the level of calbindin mRNA in extracts of whole rat cerebellum [75]. Using immunocytochemistry, we studied the effects of chronic morphine administration and morphine abstinence on levels of calbindin in cerebellar Purkinje neurons. Treatment of male rats for 5 days with either morphine injections (10 mg/kg s.c., twice daily) or subcutaneously implanted morphine pellets (75 mg/pellet, once daily) markedly decreased levels of calbindin immunoreactivity in long stretches of Purkinje cell bodies in various folia of cerebellum. After 7 days of abstinence from morphine, the number of calbindin-positive neurons was still significantly decreased, and at 14 days of abstinence, the number of labeled neurons continued to be below that in control rat brain. The effects of morphine in cerebellum were not antagonized by co-administration of the N-methyl-D-aspartate receptor antagonist, MK-801 (0.2 mg/kg, twice daily for 5 days). MK-801 alone also decreased the number of calbindin-positive cells, but in a different pattern from that of morphine. Our findings of decreased calbindin immunoreactivity in Purkinje neurons following chronic morphine administration and abstinence suggest that persistent alterations in intracellular calcium buffering may be associated with opiate tolerance and dependence in cerebellum.

Animals↗

PubMed1989

Calbindin-immunoreactive sensory neurons of dorsal root ganglion project to skeletal muscle in the chick.

In the chicken dorsal root ganglia, two neuronal subpopulations referred to as A1 and B1 share in common an immunoreactivity to antisera raised to calbindin D-28k but are distinguished by their cytological and ultrastructural characteristics. To determine the peripheral targets innervated by calbindin-immunoreactive neurons in lumbosacral dorsal root ganglia, cryostat sections of various hindlimb tissues were treated with anticalbindin antisera. Calbindin-immunostained axons were clearly detected in skeletal muscle. Large myelinated nerve fibres and afferent axon terminals in neuromuscular spindles were calbindin-immunoreactive; thin unmyelinated nerve fibres were also immunostained in nerve bundles of the perimysium. Since motoneurons and neurons of the autonomic nervous system were devoid of calbindin immunostaining, it was suggested that the immunoreactive axons found in skeletal muscle originate from sensory neurons expressing a calbindin immunoreaction in the dorsal root ganglia. This hypothesis was corroborated after introduction of wheat germ agglutinin coupled with horseradish peroxidase or colloidal gold particles into the sartorius muscle. The retrogradely transported tracer was collected only in ganglion cell bodies which displayed the ultrastructural characteristics of A1 and B1 sensory neurons. On the basis of calbindin immunoreaction and of tracer retrograde transport, it is concluded that ganglion cells of subclasses A1 and B1 contribute to the sensory innervation of skeletal muscle in the chicken.

Afferent Pathways↗

PubMed1993

Distribution of calbindin-D28k immunoreactivity in the monkey temporal lobe: the amygdaloid complex.

Calbindin-D28k is a calcium-binding protein located in a variety of neuronal cell types in many regions of the central nervous system. In the present study, we describe the distribution of calbindin-D28k-immunoreactive cells, fibers, and terminals in the monkey amygdaloid complex. Calbindin-D28k-immunoreactive neurons could be divided into four major cell types. Neurons of the first three cell types demonstrated clearly stained dendrites that were either aspiny or had a few spines on their distal portions. Type 1 cells were small, stellate, or multipolar and found throughout the amygdala. Type 2 cells were large, multipolar and were most commonly found in the deep nuclei, particularly in the lateral nucleus, intermediate division of the basal nucleus, accessory basal nucleus and in the periamygdaloid cortex. Type 3 cells were fusiform, of various sizes, and were found throughout the amygdala. Type 4 cells were quite large and lightly stained; the dendrites of these cells were usually unstained. The size, shape, and location of Type 4 labeled cell bodies suggested that they might be the large, modified pyramidal cells that constitute the projection neurons of the amygdala. Type 4 cells were observed primarily in the lateral, basal, and accessory basal nuclei and in the periamygdaloid cortex. Calbindin-D28k-immunoreactive fibers and terminals were difficult to observe in the amygdala partly because of a diffuse, finely granular neuropil labeling that was particularly dense in the anterior cortical and medial nuclei, in the central nucleus, and in the periamygdaloid cortex. The neuropil labeling was substantially lighter in the lateral, basal, and accessory basal nuclei. Conspicuous linear profiles resembling the "calbindin bundles" of the neocortex were evident in large numbers in the accessory basal nucleus, the medial portion of the parvicellular division of the basal nucleus, in the amygdalohippocampal area, and in the periamygdaloid cortex. There were calbindin-D28k-positive fibers in the stria terminalis and in the ventral amygdalofugal pathway. When the distributions of calbindin-D28k and parvalbumin immunoreactivity in the monkey amygdaloid complex were compared, it appeared that the overall distribution of these two calcium-binding proteins was generally complementary rather than overlapping.

Amygdala↗

PubMed1995

Intracerebroventricular kainic acid administration in adult rat alters hippocampal calbindin and non-phosphorylated neurofilament expression.

Calbindin and non-phosphorylated neurofilament proteins were assessed in hippocampus following a unilateral intracerebroventricular kainic acid injection at 4, 26, and 60 days post-lesion, using immunocytochemical expression. The density of calbindin-positive non-pyramidal neurons throughout the hippocampus showed no significant alteration at 4 days post-lesion, a significant decrease at 26 days post-lesion, and a partial recovery at 60 days post-lesion. In addition, calbindin immunoreactivity was dramatically reduced at 26 days post-lesion in the CA1 pyramidal and dentate granule cell layers and the mossy fibers, bilaterally. Although not significant statistically, most of these reductions showed signs of reversal at 60 days post-lesion except the CA1 pyramidal cell layer where the dramatic reductions persisted. Neurofilaments were also altered throughout the post-lesion period, particularly in abnormal expression of non-phosphorylated neurofilament proteins in mossy fibers. The apparent return of calbindin immunoreactivity in non-pyramidal neurons by 60 days post-lesion suggests that recovery from the lesion may involve remaining neuronal elements which either become reactivated with time or have the capability to express normal levels of calbindin with re-innervation. On the other hand, prolonged calbindin reductions in superficial CA1 pyramidal cells suggest sustained down-regulation of calbindin expression owing to persistent reductions in the activity of these neurons. The temporal correlation of the expression of non-phosphorylated neurofilaments in mossy fibers with their sprouting response following target loss suggests a potential role for non-phosphorylated neurofilaments in neuronal plasticity involving axonal sprouting. Alternatively, it may also suggest that injury-induced neurofilament modifications are either conducive or permissive for axonal sprouting.

Animals↗

PubMed1995

Insulin-like growth factor I is an afferent trophic signal that modulates calbindin-28kD in adult Purkinje cells.

Recent evidence suggests that Purkinje cells are specific targets of insulin-like growth factor I (IGF-I) through their entire life span. During development, Purkinje cell numbers and their calbindin-28kD content increase after IGF-I treatment in culture. In the adult, part of the IGF-I present in the cerebellum is transported from the inferior olive, and modulates Purkinje cell function. We investigated whether IGF-I produced by inferior olive neurons and transported to the contralateral cerebellum through climbing fibers may modulate the levels of calbindin-28kD in the cerebellum of adult animals. Twenty-four hr after injection of an antisense oligonucleotide of IGF-I into the inferior olive, both IGF-I and calbindin-28kD levels in the contralateral cerebellar lobe were significantly reduced, while the number of calbindin-positive Purkinje cells was unchanged. The effect of the antisense on IGF-I levels was fully reversed 3 days after its injection into the inferior olive, with a postinhibitory rebound observed at this time, while calbindin-28kD levels slowly returned to control values. A control oligonucleotide did not produce any change in either IGF-I or calbindin-28kD content in the cerebellum. These results indicate that normal levels of IGF-I in the inferior olive are necessary to maintain appropriate levels of IGF-I in the cerebellum and of calbindin-28kD in the Purkinje cell. These results also extend our previous findings on the existence of an olivo-cerebellar IGF-I-containing pathway with trophic influence on the adult Purkinje cell.

Animals↗

PubMed1994

Identification of calbindin D-9k mRNA and its regulation by 1,25-dihydroxyvitamin D3 in Caco-2 cells.

We have identified and quantified specific mRNAs in the human colonic carcinoma cell line Caco-2 by reverse transcriptase-polymerase chain reaction. Initial examination revealed that like rat duodenal mucosa, Caco-2 cells possessed mRNA for the vitamin D receptor. Using primers for human calbindin we found a 237-bp PCR product in Caco-2 cell RNA, but not from rat duodenal RNA. Primers for rat calbindin did not amplify calbindin mRNA in Caco-2 RNA, confirming a high degree of mismatch between rat and human sequences. 1,25(OH)2 vitamin D3 treatment (10 nM) significantly elevated calbindin mRNA levels 50% by 12 h, with maximal levels occurring by 48 h (fivefold elevation). Increasing concentrations of 1,25(OH)2 vitamin D3 (from 15 pM to 100 nM) caused progressive increases in calbindin mRNA levels following 48 h of treatment. Elevated calbindin mRNA levels were associated with enhancement of transcellular calcium transport. Our results are the first demonstration of vitamin D-regulated calbindin mRNA in a human intestinal cell line.

Animals↗

PubMed1998

Relative resistance of striatal neurons containing calbindin or parvalbumin to quinolinic acid-mediated excitotoxicity compared to other striatal neuron types.

To evaluate the relative ability of those striatal neuron types containing calbindin or parvalbumin to withstand a Ca(2+)-mediated excitotoxic insult, we injected the NMDA receptor-specific excitotoxin quinolinic acid (QA) into the striatum in mature adult rats and 2 months later examined the relative survival of striatal interneurons rich in parvalbumin and striatal projection neurons rich in calbindin. To provide standardization to the survival of striatal neuron types thought to be poor in Ca2+ buffering proteins, the survival was compared to that of somatostatin-neuropeptide Y (SS/NPY)-containing interneurons and enkephalinergic projection neurons, which are devoid of or relatively poorer in such proteins. The various neuron types were identified by immunohistochemical labeling for these type-specific markers and their relative survival was compared at each of a series of increasing distances from the injection center. In brief, we found that parvalbuminergic, calbindinergic, and enkephalinergic neurons all showed a generally comparable gradient of neuronal loss, except just outside the lesion center, where calbindin-rich neurons showed significantly enhanced survival. In contrast, striatal SS/NPY interneurons were more vulnerable to QA than any of these three other types. These observed patterns of survival following intrastriatal QA injection suggest that calbindin and parvalbumin content does not by itself determine the vulnerability of striatal neurons to QA-mediated excitotoxicity in mature adult rats. For example, parvalbuminergic striatal interneurons were not impervious to QA, while cholinergic striatal interneurons are highly resistant and SS/NPY+ striatal interneurons are highly vulnerable. Both cholinergic and SS/NPY+ interneurons are devoid of any known calcium buffering protein. Similarly, calbindin does not prevent striatal projection neuron vulnerability to QA excitotoxicity. Nonetheless, our data do suggest that calbindin may offer striatal neurons some protection against moderate excitotoxic insults, and this may explain the reportedly slightly greater vulnerability of striatal neurons that are poor in calbindin to ischemia and Huntington's disease.

Animals↗

PubMed1992

Calcium binding protein (calbindin D28k) immunoreactivity in the hamster superior colliculus: ultrastructure and lack of co-localization with GABA.

The expression of specific calcium binding proteins is being used increasingly as a potential neuroanatomical marker for neurons with similar functions. In this study, the distribution of calbindin D28k in the superior colliculus (SC) of adult hamsters was examined by light and electron microscopy. Calbindin immunoreactivity was prominent in specific regions and laminae of the SC throughout its rostrocaudal extent, and was found to label horizontal, vertical and stellate cell types. In addition, calbindin label highlighted "bridges" of neuronal processes in the intermediate layers. The most frequent calbindin-immunoreactive profiles seen in the electron microscope were dendrites, some of which were post-synaptic to apparent retinal ganglion cell axon terminals. Labelled axons and axon terminals were less frequently encountered. There was considerable overlap between the size distribution of calbindin D28k-immunoreactive neurons and that of GABA-immunoreactive or Nissl stained neurons in the SC. However, using a double fluorescent labelling technique, and examination of the tissue with confocal laser microscopy, no neurons were observed in the hamster SC that showed immunoreactivity for both calbindin and GABA. In this regard, the SC is similar to the mammalian lateral geniculate nucleus and the pretectum, but differs from the neocortex, where calbindin and GABA are colocalized. The demonstration in the SC, as well as other parts of the nervous system, of sub-populations of neurons that contain distinct calcium-binding proteins suggests that these neurons have different functional properties. Correlative studies may clarify the relevance of these cytoplasmic components as cell markers, as well as their different patterns of association with neurotransmitters and peptides.

Animals↗

PubMed1992

Expression of calbindin-D28k in developing and growing chick testes.

Calbindin, a 28-kDa vitamin D-dependent calcium-binding protein was localized immunohistochemically in developing and growing chick testes. The protein first appeared in the germinal epithelium of developing testes of the eight-day-old embryo and remained therein throughout development. Calbindin was not present in the germinal epithelium after hatching. Calbindin was next detected in the spermatogonia and spermatocytes of one-week-old and growing chick testes. Calbindin-positive spermatogonia and spermatocytes gradually increased in number and staining intensity as the seminiferous tubules further developed. A few interstitial Leydig cells were positive for calbindin from five-week-old and older chicks. Comparison of the time-course of appearance and increase in calbindin content in spermatogonia and spermatocytes with spermatogenesis in chickens suggests that calbindin may be involved in the mitotic process in spermatogonia and spermatocytes.

Animals↗