Vitamin D mediated intestinal calcium transport: ultrastructural distribution of calbindin-D28 K following calcitriol.
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Spatial-temporal expression of calbindin D-28K during embryonic and postnatal development of the fish retina.
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[Expression of calcium-binding proteins parvalbumin and calbindin in neurons of the neocortex grafts].
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Rat calbindin D28K: purification, quantitation, immunocytochemical localization, and comparative aspects.
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Transfer of maternally injected endocrine disruptors through breast milk during lactation induces neonatal Calbindin-D9k in the rat model.
The uterus is a highly estrogen-responsive tissue, which can be measured through changes in CaBP-9k expression. In this study, we investigated the potential for estrogenic compounds 4-tert-octylphenol (OP), nonylphenol (NP), bisphenol A (BPA), diethylstilbestrol (DES) and 17beta-estradiol (E2) to be transferred through breast milk from dam to neonate during lactation using the induction of CaBP-9k in uterine tissue as a biomarker. Dams were treated with OP, NP and BPA, dissolved in corn oil, at doses of 200, 400 and 600 mg/kg body weight per day l for 5 days after delivery. Dams and neonates were euthanized after 24h. Treatment with these estrogenic compounds increased the expression of CaBP-9k mRNA in the maternal uterus, in a dose-dependent manner. All doses of estrogenic compounds resulted in an increase in CaBP-9k protein levels. These compounds have an estrogenic effect on the maternal uterus during the lactation period as shown by the induction of both CaBP-9k mRNA and protein. In the neonatal uterus, the expression of CaBP-9k mRNA and protein significantly increased with DES exposure. There was a significant increase in CaBP-9k mRNA in neonatal uterus when the dams were treated with high doses of estrogenic compounds, but protein levels of CaBP-9k were undetectable. Taken together, these findings suggest that maternally injected estrogenic compounds may be transferred to neonates through breast milk and thus affecting uterine function, as shown by the induction of CaBP-9k gene expression in the neonatal uterus.
Animals↗
Critical role of the epithelial Ca2+ channel TRPV5 in active Ca2+ reabsorption as revealed by TRPV5/calbindin-D28K knockout mice.
The epithelial Ca(2+) channel TRPV5 facilitates apical Ca(2+) entry during active Ca(2+) reabsorption in the distal convoluted tubule. In this process, cytosolic Ca(2+) remains at low nontoxic concentrations because the Ca(2+) influx is buffered rapidly by calbindin-D(28K). Subsequently, Ca(2+) that is bound to calbindin-D(28K) is shuttled toward the basolateral Ca(2+) extrusion systems. For addressing the in vivo role of TRPV5 and calbindin-D(28K) in the maintenance of the Ca(2+) balance, single- and double-knockout mice of TRPV5 and calbindin-D(28K) (TRPV5(-/-), calbindin-D(28K)(-/-), and TRPV5(-/-)/calbindin-D(28K)(-/-)) were characterized. These mice strains were fed two Ca(2+) diets (0.02 and 2% wt/wt) to investigate the influence of dietary Ca(2+) content on the Ca(2+) balance. Urine analysis indicated that TRPV5(-/-)/calbindin-D(28K)(-/-) mice exhibit on both diets hypercalciuria compared with wild-type mice. Ca(2+) excretion in TRPV5(-/-)/calbindin-D(28K)(-/-) mice was not significantly different from TRPV5(-/-) mice, whereas calbindin-D(28K)(-/-) mice did not show hypercalciuria. The similarity between TRPV5(-/-)/calbindin-D(28K)(-/-) and TRPV5(-/-) mice was supported further by an equivalent increase in renal calbindin-D(9K) expression and in intestinal Ca(2+) hyperabsorption as a result of upregulation of calbindin-D(9K) and TRPV6 expression in the duodenum. Elevated serum parathyroid hormone and 1,25-dihydroxyvitamin D(3) levels accompanied the enhanced expression of the Ca(2+) transporters. Intestinal Ca(2+) absorption and expression of calbindin-D(9K) and TRPV6, as well as serum parameters of the calbindin-D(28K)(-/-) mice, did not differ from those of wild-type mice. These results underline the gatekeeper function of TRPV5 being the rate-limiting step in active Ca(2+) reabsorption, unlike calbindin-D(28K), which possibly is compensated by calbindin-D(9K).
Absorption↗
Neurochemical characterization of AMPA receptor-containing neurons in the mediolateral septal area of the rat.
The lateral septum receives a massive innervation by excitatory amino acid-containing limbic cortical and hypothalamic afferents, and previous studies have described a wide distribution of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor-containing neurons in this area. The aim of this study was to determine whether different subtypes of AMPA receptors are expressed in the same neurons. Furthermore, considering the fact that a population of lateral septal cells, the "somatospiny neurons," are GABAergic calbindin-containing cells, the coexistence of each subtype of AMPA receptor with calbindin was also investigated. Colocalization experiments were performed on adjacent vibratome sections of the lateral septal area for GluR1 and GluR2/3 AMPA-receptor subunits, GluR1 and calbindin, GluR2/3 and calbindin, as well as GluR1 plus calbindin and GluR2/3 plus calbindin, using the "mirror" colocalization technique. The results are summarized as follows: (1) GluR1 is present in the soma and most intensively expressed in dendrites and somatic and dendritic spines; while GluR2/3 is associated with the soma and proximal dendrites of the neurons. (2) Forty-one percent of the AMPA receptor-containing neurons cocontain GluR1 and GluR2/3. (3) Thirty-eight percent of GluR1- and 28% of GluR2/3-labeled cells express calbindin. (4) Sixty-two percent of the calbindin-immunoreactive neurons contain GluR1 and 51% of them express GluR2/3. (5) Half of the neurons expressing both GluR1 and GluR2/3 also contain calbindin. (6) The distribution of GluR1 plus GluR2/3-containing, GluR1 plus calbindin-containing, and GluR2/3 plus calbindin-containing neurons in the lateral septum are homogeneous. This study indicates the existence of multiple populations of AMPA receptor- and calbindin-containing neurons in the lateral septal area.
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Analysis of vitamin D-dependent calcium-binding protein messenger ribonucleic acid expression in mice lacking the vitamin D receptor.
To investigate the roles of the receptor-dependent actions of 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] in the regulation of vitamin D-dependent calcium-binding proteins (calbindin-D), the messenger RNA (mRNA) levels of calbindin-D9k and -28k were examined in vitamin D receptor (VDR)-ablated mice and control littermates. In VDR-ablated mice, calbindin-D9k mRNA was dramatically reduced in the intestine, kidneys, lungs, and brain; however, calbindin-D28k mRNA was only moderately decreased in the kidney. After 1,25-(OH)2D3 injection, calbindin-D9k mRNA levels and renal and alveolar calbindin-D28k mRNA levels were induced in control animals, but not in the homozygous mice. When the mice were fed a diet high in lactose, calcium, and phosphorus, intestinal calbindin-D9k mRNA levels in the homozygous mice were restored to those in their control littermates. However, this diet failed to normalize extraintestinal calbindin mRNA levels. These findings demonstrate that the receptor-dependent actions of 1,25-(OH)2D3 regulate calbindin-D9k gene expression and that tissue-specific factors modulate the effects of 1,25-(OH)2D3 on calbindin-D28k gene expression. These data also demonstrate that in the absence of a functional VDR, a high local concentration of calcium, phosphorus, and/or lactose in the intestinal lumen can normalize intestinal calbindin-D9k mRNA levels.
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Renal and intestinal calcium-binding proteins in normal and uraemic rats.
The effect of chronic uraemia on the concentrations of the 28 kDa renal and 9 kDa intestinal calcium-binding proteins (calbindin-D28K and calbindin-D9K) was investigated in rats. Calbindin-D9K was measured by a competitive enzyme-linked immunoadsorbent assay and calbindin-D28K by rocket immunoelectrophoresis. Chronic uraemia was induced by 5/6 nephrectomy and the results were compared to sham-operated animals. Rats were fed on a diet containing 0.9% calcium and 1.2% phosphorous. Plasma creatinine and plasma urea were elevated in the nephrectomized rats (p less than 0.001), while plasma-1,25-dihydroxycalciferol vitamin D and fractional calcium absorption were unchanged. Plasma parathyroid hormone was significantly elevated in the uraemic rats. The concentration of calbindin-D28K in renal tissue was increased (p less than 0.001) in rats with chronic uraemia and a direct correlation was found between renal calbindin-D28K and plasma urea (p less than 0.05). Intestinal calbindin-D9K correlated inversely with plasma creatinine (p less than 0.05), but the mean level of calbindin-D9K was unchanged in this model of moderate chronic uraemia. Thus, different regulatory mechanisms control levels of calbindin-D9K and calbindin-D28K.
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Appearance and distribution of two Ca2+-binding proteins during development of the cochlea in the musk shrew.
In the developing cochlea of the musk shrew, Suncus murinus, the localization of two Ca2+-binding protein, calbindin and calmodulin, which are thought to play different roles in the nervous system, was examined during gestational and postpartum periods. Calbindin is thought to play a Ca2+ buffering role, while calmodulin activates other proteins. Cochleae from the musk shrews sacrificed from gestational day (GD) 15 to postnatal day (PP) 9 and as adults, were immunohistochemically analyzed. The localization and order of appearance of calmodulin in sensorineural elements were similar to those of calbindin, except for timing of appearance. Calmodulin-staining was recognized first in the spiral ganglion neurons on GD21, followed by the inner hair cells (IHCs) on GD23 and outer hair cells (OHCs) on GD26, while calbindin immunoreactivity in the spiral ganglion neurons on GD19, the IHCs on GD21 and the OHCs on GD23. In hair cells, during development, immunostaining of calbindin and calmodulin was initially seen in the cytoplasm, followed by the cuticular plate. Cytoplasmic staining then decreased in mature hair cells. Non-sensorineural components also showed positivity for both calbindin and calmodulin. The lateral wall of the cochlear duct was positive for calbindin, while the stria vascularis was positive for calmodulin. Immunoreactivity for calbindin was present earlier than that of calmodulin in sensorineural elements, suggesting that in the developing cochlea, calbindin and calmodulin have different functions and that Ca2+ buffering capacity, which is regulated by Ca2+ buffer proteins, such as calbindin, may be required before trigger proteins, such as calmodulin, function.
Aging↗
Duodenal calcium binding protein and active calcium transport in rats: are they functionally related?
The effects of calcitriol and a novel calcitriol analogue, 22-oxacalcitriol (OCT) on duodenal Ca transport, calbindin-D9k mRNA, and calbindin-D9k content were studied in two animal models reflecting common human pathologies, namely arterial hypertension and chronic renal failure, as well as in normal rats. The hormone or its analogue were administered intraperitoneally to vitamin-D-replete rats. Active Ca transport was increased in both spontaneously hypertensive rats (SHR) and in normotensive control WKY rats 5 h after calcitriol dosing of either 60 and 600 ng per rat. In WKY, calbindin-D9k content was slightly increased after the injection of 60 ng calcitriol, but not of 600 ng calcitriol whereas calbindin-D9k mRNA stayed essentially unchanged. In contrast, active Ca transport was significantly stimulated after the higher dose of 600 ng calcitriol. In SHR, while both doses of calcitriol increased active Ca transport, they had no stimulatory effect on calbindin-D9k mRNA or protein. In chronically uraemic rats, active Ca transport, duodenal calbindin-D9k and calbindin-D9k mRNA were stimulated after the injection of two subsequent doses of 300 ng calcitriol per rat. OCT treatment at same dosage led to a similar stimulation of calbindin-D9k and calbindin-D9k mRNA, but failed to induce an increase in active Ca transport. These results show that the stimulation of intestinal active Ca transport and calbindin-D9k can be entirely dissociated at the protein synthesis and the mRNA expression level (1) after calcitriol administration to normal and hypertensive rats, and (2) after OCT administration to uraemic rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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Calcium-binding proteins in primate basal ganglia.
This paper describes the distribution of the calcium-binding proteins calbindin-D28k. Parvalbumin and calretinin in primate basal ganglia. The data derive from immunocytochemical studies undertaken in squirrel monkeys (Saimiri sciureus) and in normal human individuals. In the striatum, calbindin labels medium-sized spiny projection neurons whereas parvalbumin and calretinin mark two separate classes of aspiny interneurons. The striatal matrix compartment is markedly enriched with calbindin while striatal patches (striosomes) display a calretinin-rich neuropil. In the pallidum, virtually all neurons contain parvalbumin but none express calbindin. Calretinin occurs only in a small subpopulation of both large and small pallidal neurons. In the subthalamic nucleus, there exists a multitude of parvalbumun-positive cells and fibers but the number of calretinin and calbindin-positive neuronal elements is small. In the substantia nigra/ventral tegmental area complex, calbindin and calretinin occur principally in dopaminergic neurons of the dorsal tier of the pars compacta and in those of the ventral tegmental area. Parvalbumin is strictly confined to the GABAergic neurons of the pars reticulata and lateralis. Calbindin-rich fibers abound in the pars reticulata and lateralis, while calretinin-positive axons are confined to the pars compacta. These results indicate that calbindin and parvalbumin are distributed according to a strikingly complementary pattern in primate basal ganglia. Calretinin is less ubiquitous but occurs in all basal ganglia components where it labels distinct subsets of neurons. Such highly specific patterns of distribution indicate that calbindin, parvalbumin and calretinin may work in synergy within primate basal ganglia.
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Colocalization of calcium-binding proteins and GABA in neurons of the rat basolateral amygdala.
The basolateral amygdala contains subpopulations of non-pyramidal neurons that express the calcium-binding proteins parvalbumin, calbindin-D28k (calbindin) or calretinin. Although little is known about the exact functions of these proteins, they have provided useful markers of specific neuronal subpopulations in studies of the neuronal circuitry of the cerebral cortex and other brain regions. The purpose of the present study was to investigate whether basolateral amygdalar non-pyramidal neurons containing parvalbumin, calbindin, or calretinin exhibit immunoreactivity for GABA, and to determine if calretinin is colocalized with parvalbumin or calbindin in the rat basolateral amygdala. Pyramidal neurons were distinguished from non-pyramidal neurons on the basis of staining intensity. Using immunofluorescence confocal laser scanning microscopy, as well as the 'mirror technique' on immunoperoxidase-stained sections, it was found that there was virtually no colocalization of calretinin with parvalbumin or calbindin, but that the great majority of basolateral amygdalar non-pyramidal neurons containing parvalbumin, calbindin, or calretinin exhibited GABA immunoreactivity. Calbindin-positive neurons constituted almost 60% of the GABA-containing population in both subdivisions of the basolateral nucleus and more than 40% of the GABA-containing population in the lateral nucleus. Parvalbumin-positive neurons constituted 19-43% of GABA-immunoreactive neurons in the basolateral amygdala, depending on the nucleus. Calretinin-positive non-pyramidal neurons constituted about 20% of the GABA-positive neuronal population in each nucleus of the basolateral amygdala. These findings indicate that non-pyramidal neurons containing parvalbumin, calbindin, or calretinin comprise the majority of GABA-containing neurons in the basolateral amygdala, and that the calretinin subpopulation is distinct from non-pyramidal subpopulations containing parvalbumin and calbindin. These separate neuronal populations may play unique roles in the inhibitory circuitry of the amygdala.
Amygdala↗
Differential Calcium Binding Protein Immunoreactivity Distinguishes Classes of Relay Neurons in Monkey Thalamic Nuclei.
The distributions of neurons displaying immunoreactivity for two calcium binding proteins, parvalbumin and 28Kd calbindin, were studied in the thalamus of M. fascicularis. Colocalization experiments were carried out to determine the extent to which parvalbumin- and calbindin-like immunoreactivity was found in the same cells and the extent to which either was localized in GABAergic interneurons. Anterograde and retrograde tracing experiments involving the fluorescent tracer, fast blue, were also used to determine that cells expressing the calcium binding proteins projected upon the cerebral cortex. In the dorsal thalamus, nuclei are distinguished by different patterns of parvalbumin-like and calbindin-like immunoreactivity. In certain nuclei, for example the lateral dorsal and anterior pulvinar, neurons express immunoreactivity for only one of the calcium binding proteins. In others, neurons in different layers, for example the dorsal lateral geniculate nucleus, or in different compartments, for example the intralaminar nuclei, express immunoreactivity for either parvalbumin or calbindin; in other nuclei, for example the ventral group, neurons are mixed and immunoreactivity for parvalbumin and calbindin is commonly colocalized. In the ventral thalamus and epithalamus, similar patterns are observed. Colocalization of parvalbumin- and GABA-immunoreactivity is found in all cells of the reticular nucleus but only in certain cells in selected nuclei of the dorsal thalamus, namely the dorsal lateral geniculate and magnocellular medial geniculate. No calbindin-positive cells are also GABA-positive. Most parvalbumin and/or calbindin positive cells in the dorsal thalamus project to the cerebral cortex, as indicated by the retrograde tracing studies, and many parvalbumin positive fibres entering the cerebral cortex could also be shown to contain fast blue anterogradely transported from a thalamic injection. Most of the major sensory and motor pathways entering the dorsal thalamus express parvalbumin immunoreactivity. The optic tract also expresses calbindin immunoreactivity but most other calbindin positive fibres entering the thalamus ascend in the midbrain tegmentum. The differential distributions of parvalbumin and calbindin implied by these results suggest that thalamic cells belonging to different functional systems and projecting differentially upon the cerebral cortex can be distinguished by differential expression of these or closely related calcium binding proteins. This may yield clues to their differential responsivity to afferent driving.
Journal Article↗
Endogenous Ca2+ buffer concentration and Ca2+ microdomains in hippocampal neurons.
Ca2+-binding proteins are ubiquitously expressed throughout the CNS and serve as valuable immunohistochemical markers for certain types of neurons. However, the functional role of most Ca2+-binding proteins has to date remained obscure because their concentration in central neurons is not known. In this study, we investigate the intracellular concentration of the widely expressed Ca2+-binding protein calbindin-D28k in adult hippocampal slices using patch-clamp recordings and immunohistochemistry. First, we show that calbindin-D28k freely exchanges between patch pipette and cytoplasm during whole cell patch-clamp recordings with a time constant of approximately 10 min. Substituting known concentrations of recombinant calbindin-D28k in patch pipettes enabled us to determine the endogenous calbindin-D28k concentration by postrecording immunohistochemistry. Using this calibration procedure, we find that mature granule cells (doublecortin-) contain approximately 40 microm, and newborn granule cells (doublecortin+) contain 0-20 microm calbindin-D28k. CA3 stratum radiatum interneurons and CA1 pyramidal cells enclose approximately 47 and approximately 45 microm calbindin-D28k, respectively. Numerical simulations showed that 40 microm calbindin-D28k is capable of tuning Ca2+ microdomains associated with action potentials at the mouth of single or clustered Ca2+ channels: calbindin-D28k reduces the increment in free Ca2+ at a distance of 100 and 200 nm by 20 and 35%, respectively, and strongly accelerates the collapse of the Ca2+ gradient after cessation of Ca2+ influx. These data suggest that calbindin-D28k equips hippocampal neurons with approximately 160 microm mobile, high-affinity Ca2+-binding sites (kappa(S) approximately 200) that slow and reduce global Ca2+ signals while they enhance the spatiotemporal fidelity of submicroscopic Ca2+ signals.
Aging↗
Calcium binding proteins as molecular markers for cat geniculate neurons.
Immunocytochemistry revealed that in the cat dorsal lateral geniculate nucleus (dLGN) almost all parvalbumin-positive cells are GABAergic and about 56% of the calbindin D-28K (calbindin-immunoreactive neurons are also GABA-positive. On the other hand, in the same nucleus, almost all GABAergic neurons contain parvalbumin, and about 89% of the GABA-immunoreactive neurons contain calbindin. Double-labeling with calbindin and parvalbumin revealed that approximately 50% of the immunoreactive neurons are double-stained. In the PGN, virtually all neurons are GABA and parvalbumin-positive. Only a few scattered cells were also calbindin-immunoreactive. These results show that GABAergic geniculate cells can be differentiated on the basis of their calcium-binding protein immunoreactivity. Four types of immunoreactive cells are described here: (1) cells positive for GABA, parvalbumin and calbindin, (2) cells positive for GABA and parvalbumin, but negative for calbindin, (3) cells negative for GABA and parvalbumin, but positive for calbindin, (4) cells negative for GABA, parvalbumin and calbindin.
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Expression of a low-molecular-weight (10 kDa) calcium binding protein in glial cells of the brain of the trout (Teleostei).
Calcium-binding proteins of the EF-hand family are widely distributed in the vertebrate central nervous system. In the present study of the trout brain, immunocytochemistry with a monoclonal antibody against chick gut calbindin-28k and a polyclonal antibody against bovine S100 protein specifically stained ependymocytes and radial glia cells with identical patterns. Western blot analysis of trout brain extracts with the antibodies to S100 and calbindin stained the same low-molecular-weight (10 kDa) protein band. In rat brain extracts, however, the monoclonal antibody to calbindin recognized a major protein band with molecular weight corresponding to that of calbindin-28k. This indicates that the trout protein is a new calcium-binding-like (calbindin-like) molecule that is immunologically related to both S100 and calbindin. Immunocytochemical studies of the trout brain using the antibodies to CaB and S100 showed that ependymocytes were stained in most ventricular regions, except in a few specialized ependymal areas of the ventral telencephalon, epithalamus, hypothalamus (including the paraventricular organ and saccus vasculosus) and brain stem. Immunocytochemistry also indicated the presence of calbindin-like protein in radial glia cells of several regions of the brain (thalamus, pretectal region, optic tectum, and rhombencephalon). Differences in immunoreactivity between neighbouring ependymal areas suggest that this protein may be a useful marker of different territories. All immunoreactive glial cells were nicotin-adenin-dinucleotide-phosphate diaphorase-positive, although this enzymohistochemical reaction is not specific for these glial cells since it reveals oligodendrocytes and some neurons. Immunoreactivity appears at different developmental stages in the different brain regions, with a broadly caudorostral gradient, suggesting that the expression of this protein is developmentally regulated. Comparison of the distribution of the calbindin-like protein with that of glial acidic fibrillary protein indicates that calbindin-like immunocytochemistry is a specific technique for revealing radial glia and ependymocytes in the trout.
Age Factors↗
Coexistence of calcium-binding proteins in vagal and glossopharyngeal sensory neurons of the rat.
The presence and coexistence of the calcium-binding proteins (CaBPs), calbindin D-28k, parvalbumin and S100 protein, were immunohistochemically examined in the glossopharyngeal and vagal sensory ganglia, the carotid body and taste buds. The CaBPs were found in each ganglion with the nodose ganglion containing the largest number of CaBP-immunoreactive (ir) cells (calbindin D-28k > or = S100 >> parvalbumin). The coexistence of CaBPs was found in neurons of the nodose, petrosal, and jugular ganglia. Calbindin D-28k-ir neurons in the nodose and petrosal ganglia frequently colocalized S100-ir whereas calbindin D-28k-ir neurons in the jugular ganglion less frequently contained S100-ir. Only small percentages of calbindin D-28k-ir neurons in each ganglion colocalized parvalbumin. Similarly, S100-ir neurons in the nodose and petrosal ganglia frequently colocalized calbindin D-28k-ir whereas S100-ir neurons in the jugular ganglion less frequently contained calbindin D-28k-ir. Moderate to small percentages of S100-ir neurons in each ganglion colocalized parvalbumin. Parvalbumin-ir neurons nearly always colocalized S100-ir in the nodose, petrosal and jugular ganglia. Moderate to small percentages of parvalbumin-ir neurons in each ganglion colocalized calbindin D-28k. Whereas calbindin D-28k- and S100-ir were colocalized in nerve fibers and cells within taste buds of circumvallate papilla of the tongue, the coexistence of these CaBPs could not be determined in the carotid body. These findings suggest a co-operative role for CaBPs in the functions of subpopulations of nodose and petrosal ganglia neurons.
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