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PubMed2006

Anomalous inhibitory circuits in cortical tubers of human tuberous sclerosis complex associated with refractory epilepsy: aberrant expression of parvalbumin and calbindin-D28k in dysplastic cortex.

Damage or loss of inhibitory cortical gamma-aminobutyric acid (GABA)ergic interneurons is associated with impaired inhibitory control of neocortical pyramidal cells, leading to hyperexcitability and epileptogenesis. The calcium binding proteins parvalbumin and calbindin-D(28k) are expressed in subpopulations of GABAergic local circuit neurons in the neocortex and can serve as neuronotypic markers. Parvalbumin and calbindin-D(28k) facilitate the neuron's ability to sustain firing and provide neuroprotection. The goal of this study was to assess the hitherto unknown status of inhibitory interneurons in cortical tubers of human tuberous sclerosis complex. Surgically excised cortical tubers from three patients with tuberous sclerosis complex were evaluated immunohistochemically with antibodies to parvalbumin and calbindin-D(28k). Cortical specimens from young patients with intractable seizures, including microdysgenesis (n = 3), postischemic cortical scarring (n = 1), porencephaly (n = 1), postictal gliosis (n = 3), and low-grade neuronal or glial tumors (n = 5), were also examined for comparison. In cortical tubers, calcium binding protein immunoreactivities (calbindin-D(28k) > parvalbumin) were present in medium- or large-size dysplastic neurons, whereas giant or ballooned cells were parvalbumin or calbindin-D(28k) negative. In microdysgenesis, a nearly normal number of parvalbumin-positive neurons and a decreased number of calbindin-D(28k)-positive neurons were present. In peritumoral but more so in gliotic cortex, a coordinate decrease of parvalbumin and calbindin-D(28k) immunoreactivities was present. Our findings indicate that the expression of parvalbumin or calbindin-D(28k) by subpopulations of dysplastic neurons in cortical tubers is aberrant and denotes dysfunctional inhibitory circuits inept for excitoprotection.

Adolescent↗
PubMed1992

Estrogen inhibits calbindin-D28k expression in mouse uterus.

The cellular localization and hormonal controls of calbindin-D9k expression in the rodent reproductive tract have suggested new functions for this protein. The present studies were undertaken to extend the earlier studies of calbindin-D9k to the related protein, calbindin-D28k. Immunohistochemical studies revealed that calbindin-D28k was absent from female rat reproductive tissues, but was abundantly expressed in immature mouse uterus and oviduct. Immunoreactivity was restricted to the endometrial and glandular epithelium of the uterus and the oviductal epithelium. Neither 1,25-dihydroxyvitamin D- nor strontium-containing diets (to blunt 1,25-dihydroxyvitamin D production) affected expression of calbindin-D28k. Uterine, but not oviductal, calbindin-D28k decreased markedly at sexual maturity; this pattern persisted in pregnant mice and was reproduced in immature mice by the administration of estradiol (3 micrograms/day for 3 days). RNA extraction and Northern analyses demonstrated that estrogen markedly decreased calbindin-D28k mRNA abundance in the uterus, but not in the oviduct. These findings suggest that estrogen affects mammalian calbindin-D28k expression and represent a rare example of estrogen-induced down-regulation of gene expression.

Animals↗
PubMed1991

Calbindin-D9k and parvalbumin are exclusively located along basolateral membranes in rat distal nephron.

There is strong evidence that vitamin D-dependent Ca(2+)-binding proteins, i.e., calbindin-D9k and calbindin-D28k, facilitate diffusion of Ca2+ through the cytosolic compartment of renal and intestinal cells, which transport Ca2+ transcellularly. In the study presented here, parvalbumin, calbindin-D9k, and calbindin-D28k were localized precisely by immunocytochemistry in rat kidney. Antisera recognizing specifically the thick ascending loop of Henle, the connecting tubules and collecting ducts, and the intercalated cells of the collecting ducts were used to identify different cell types. In rat kidney cortex, parvalbumin and calbindin-D9k colocalized in the thick ascending loop of Henle, the distal convoluted tubule, the connecting tubule, and the intercalated cells of the collecting duct. Strikingly, in all responsive cells, parvalbumin and calbindin-D9k were exclusively present in a thin layer along the basolateral membrane. In contrast, calbindin-D28k was only present in the distal convoluted and connecting tubule, where it was evenly distributed through the cytosol. In conclusion, the exclusive localization of parvalbumin and calbindin-D9k at the basolateral membrane of immunopositive renal cells implies their involvement in the regulation of transport processes located in these membranes rather than a role as intracellular Ca2+ buffer and Ca2+ shuttle between the two opposing membranes.

Animals↗
PubMed1995

In situ hybridization of calbindin-D 28 k transcripts in undecalcified sections of the rat continuously erupting incisor.

Calbindin-D9k and calbindin-D-28k genes are useful systems to investigate the tissue- and stage-specificity as well as the hormonal control of gene expression. Since they regulate cellular calcium mobilization, their study may be of interest in mineralized tissues. However, thus far, immunocytochemical labelling has been mainly realized in these systems. In order to set up methods for mRNA investigation, in situ hybridization of calbindin-D28k mRNAs was performed in the continuously erupting incisor of Sprague-Dawley rats (15-, 30-, and 56-day-old). 35S UTP labelled antisense and sense riboprobes specific for brain calbindin-D 28k were used for in situ hybridization. Specific and non-specific signals could not be discerned when studying decalcified samples. In contrast, on sections not pretreated with EDTA, calbindin-D 28k transcripts (in tooth and kidney) appeared strongly labelled with antisense probes, while sense probes provided a negligible background. In ameloblasts, the signal (i.e., calbindin-D 28k mRNA levels) increased during the presecretory stage. Different mRNA gradients and subcellular distribution patterns characterized the secretory and maturation stages. A nuclear labelling was observed, associated with the highest levels of transcripts. These data suggest a developmental control of calbindin-D28k mRNA transcription. Calbindin-D28k gene expression appears to be up-regulated during the initiation of both secretory and maturation stages of enamel mineralization.

Ameloblasts↗
PubMed1990

Regulation of calbindin-D28K gene expression by 1,25-dihydroxyvitamin D3 in chick kidney.

We report here the use of a cloned cDNA for the avian calbindin-D28K (28 kD, vitamin D-dependent calcium binding protein, CaBP) to investigate the expression of the chick calbindin gene in the kidney. All three cal-bindin-D28K mRNA species (2000, 2600, and 3100 nucleotide transcripts) were present in the kidney tissue of chronically vitamin D-deficient (-D) chicks; this basal constitutive level of expression was, however, enhanced by administration of the vitamin D3 metabolite, 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] in both a time- and dose-dependent manner. D-deficient chick renal calbindin-D28K protein levels (measured by ELISA) were maximally (twofold) stimulated by 6.5 nmole per animal of 1,25-(OH)2D3 when measured 48 h later; a concomitant level of augmentation of calbindin-D28K mRNA accumulation was also observed at this time. Time course experiments showed that enhanced renal calbindin-D28K mRNA accumulation (in -D chicks) was significantly stimulated as early as 8 h and were maximal 12 h after a single pharmacologic dose of 1,25-(OH)2D3; this elevated level of gene expression was maintained for at least 72 h. Renal calbindin-D28K protein levels (constitutively expressed in the -D chick) were significantly stimulated (twofold) as early as 12 h following the single dose of steroid hormone; the level of calbindin-D28K also remained elevated for a minimum of 72 h. Collectively, these data indicate that 1,25-(OH)2D3 acts upon the renal calbindin-D28K gene in a manner similar to that operable in the intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Epithelial and neuronal calbindin in avian intestine. An immunohistochemical study.

It is well known that calbindin immunoreactivity is highly concentrated in the duodenal absorptive cells of young birds. We have shown that in the adult intestine of three avian species, calbindin content is much more variable. In addition to absorptive cells, we have detected throughout the gut of both sexes of the domestic fowl and in the large intestine of the Japanese quail a second type of calbindin-positive epithelial cell which has the shape of a typical endocrine cell. These cells were particularly abundant in the large intestine, in contrast to the usual distribution of endocrine cells along the gut. Calbindin was also detected in the nervous system of the intestine. Calbindin-positive nerve fibres were rare in the duodenum and ileum, numerous in plexuses and nerve processes in both muscular layers and lamina propria of the large intestine in domestic fowl and Japanese quail. In the mallard, nerve fibres were rarely calbindin positive while definitively positive for VIP. Calbindin of the peripheral nervous system of the domestic fowl and Japanese quail comigrates with the duodenal calbindin (27,000 dalton) in SDS gel electrophoresis.

Animals↗
PubMed1995

Postnatal development of calbindin-D28k immunoreactivity in the cerebral cortex of the cat.

To learn about maturational patterns of nonpyramidal neurons in the cerebral cortex, calbindin-D28k immunoreactivity was studied in the kitten cortex. Immunoreactive neurons first appear in the cortical and subcortical areas related to the limbic system, including the cingulate and retrosplenial cortices, and in the secondary motor areas. These are followed by the primary motor and sensory association areas and, finally, by the primary sensory areas. In all cortical areas, calbindin-D28k immunoreactivity first develops in layer V pyramidal neurons and later in nonpyramidal neurons, except in the primary sensory areas, where immunoreactive pyramidal neurons are not found at any age. Transient calbindin-D28k immunoreactivity occurs in pyramidal neurons that are mainly localized in the cingulate and retrosplenial cortices and in the secondary motor area, as well as in nonpyramidal neurons localized in the subplate and layer I, and in a subset of large multipolar and bitufted neurons in layer VI. Nonpyramidal neurons localized in layers II to IV, and some neurons in layer VI, develop permanent calbindin-D28k immunoreactivity. Calbindin-D28k immunoreactivity labels subsets of GABAergic interneurons that form vertical axonal tufts, so that temporal and regional patterns of calbindin-D28k immunoreactivity during development may be implicated in the maturation of columnar (vertical) inhibition in the cerebral cortex. In addition to neurons, corticofugal and afferent fibres of subcortical origin exhibit calbindin-D28k immunoreactivity. Transient calbindin-D28k immunoreactivity occurs in corticofugal fibres arising from the cingulate and prefrontal cortices, which are probably corticostriatal projection fibres. In contrast, permanent immunoreactivity occurs in what are probably thalamocortical fibres ending in layer IV, and in punctate terminals located in the upper third of layer I.

Animals↗
PubMed1996

Coexistence of calbindin D-28k and NADPH-diaphorase in vagal and glossopharyngeal sensory neurons of the rat.

The presence and coexistence of calbindin D-28k-immunoreactivity (ir) and nicotinamide adenosine dinucleotide phosphate (NADPH)-diaphorase activity (a marker of neurons that are presumed to convert L-arginine to L-citrulline and nitric oxide) were examined in the glossopharyngeal and vagal sensory ganglia (jugular, petrosal and nodose ganglia) of the rat. Calbindin D-28k-ir nerve cells were found in moderate and large numbers in the petrosal and nodose ganglia, respectively. Some calbindin D-28k-ir nerve cells were also observed in the jugular ganglion. NADPH-diaphorase positive nerve cells were localized to the jugular and nodose ganglia and were rare in the petrosal ganglion. A considerable portion (33-51%) of the NADPH-diaphorase positive neurons in these ganglia colocalized calbindin D-28k-ir. The presence and colocalization of calbindin D-28k-ir and NADPH-diaphorase activity in neurotransmitter-identified subpopulations of visceral sensory neurons were also studied. In all three ganglia, calcitonin gene-related peptide (CGRP)-ir was present in many NADPH-diaphorase positive neurons, a subset of which also contained calbindin D-28k-ir. In the nodose ganglion, many (42%) of tyrosine hydroxylase (TH)-ir neurons also contained NADPH diaphorase activity but did not contain calbindin D-28k-ir. These data are consistent with a potential co-operative role for calbindin D-28k and NADPH-diaphorase in the functions of a subpopulation of vagal and glossopharyngeal sensory neurons.

Animals↗
PubMed1992

Immunohistochemical changes of neuronal calcium-binding proteins parvalbumin and calbindin-D-28k following unilateral deafferentation in the rat visual system.

The neuron-specific calcium-binding proteins, parvalbumin and calbindin-D-28k, were studied in the subcortical visual system of normal and unilaterally deafferented albino rats. Immunohistochemistry with monoclonal antibodies was used on vibratome sections through optic tract (OT), dorsal lateral geniculate nucleus (dLGN), olivary pretectal nucleus (OPN), and superior colliculus (SC). In controls, OT stained strongly for parvalbumin and weakly for calbindin-D-28k. The dLGN contained a plexus of parvalbumin-positive fibers. In dLGN, calbindin-D-28k-antibodies showed strong labeling of some neurons with long dendrites and weak staining of the cytoplasm in other neurons. In OPN, parvalbumin stained a ring of neurons and terminals in the shell region, whereas calbindin-D-28k was contained in medial cell populations. In SC, parvalbumin was contained in fibers, terminals, and neurons throughout the visual layer. Calbindin-D-28k showed a laminar distribution of neurons with a predominance in deep portions of superficial grey matter and in ventral portions of stratum opticum. Following unilateral deafferentation induced by optic nerve section, retinal axons showed immunohistochemical changes related to Wallerian degeneration and target neurons reacted by changes of calcium-binding proteins. Parvalbumin and calbindin-D-28k immunostaining decreased during Wallerian degeneration of OT. In the deafferented dLGN, immunohistochemical labeling for calbindin-D-28k declined in strongly stained neurons from 4 to 21 days after lesion. Measurement of dendritic length per number of cells or per area of dLGN showed a significant decline for the contralateral side at 4, 8, and 21 days (ANOVA, P less than 0.05). In deafferented OPN, terminal-like staining for parvalbumin decreased and neuronal labeling was enhanced. In deafferented SC, the neuronal and dendritic staining for parvalbumin increased beginning from Day 1 on and persisting at Day 21, whereas fibers and terminal-like elements decreased in staining. Measurement of parvalbumin-positive neurons per area of SC showed a significant increase of labeling in the contralateral side from Day 1 to Day 21 (ANOVA, P less than 0.05). These studies show that cellular responses to deafferentation of visual neurons involve a regulation of calcium-binding proteins. The decline in staining for calbindin-D-28k in dLGN may relate to reduced retinal afferent activity. The progressive cellular changes in parvalbumin staining may be related to unmasking of intrinsic neurons after removal of parvalbumin-containing, afferent fibers and terminals. Additionally, the changes of parvalbumin labeling in SC neurons may reflect a plastic reorganization of local circuits known to occur in rat SC in response to deafferentation.

Afferent Pathways↗
PubMed1994

The development of parvalbumin and calbindin-D28k immunoreactive interneurons in kitten visual cortical areas.

Calbindin-D and parvalbumin are calcium binding proteins which are found in non-overlapping subpopulations of GABA-ergic interneurons in mammalian neocortex. We studied the development of these calcium-binding proteins in interneurons of cat striate and extrastriate cortical areas which have differing patterns of connectivity and follow different developmental timetables. We examined primary visual areas 17 and 18, secondary visual area 19, medial lateral suprasylvian and lateral suprasylvian areas (MLS and LLS) and association areas 7 and the splenial visual area from the day of birth (P0) through P101. Parvalbumin-immunoreactive (ir) interneurons followed the inside-out pattern of maturation of cortical laminae. They were located only in infragranular layers at the earliest ages and were not observed in the overlying cortical plate. At 3 weeks of age, when cortical lamination is mature, parvalbumin stained cells were found in all cortical layers except layer I. The number of stained secondary and tertiary dendrites in the parvalbumin-ir interneuronal population decreased with age. This change was associated with a shift in the molecular weight of parvalbumin detected on Western blots. During the first postnatal week, the area 17/18 border contained more parvalbumin-ir neurons than other visual areas. The developmental pattern of calbindin staining differed considerably from the parvalbumin staining pattern. Very few calbindin-ir interneurons were seen in area 17 during the first 2 weeks of life. In lateral cortical areas, calbindin-ir neurons were located in cortical plate, infragranular layers of cortex and white matter/subplate. Calbindin-ir neurons increased in supragranular layers of secondary cortical areas by P7 and in area 17 by P20. In the mature cortex, the calbindin staining pattern was bilaminar, with a dense band of calbindin-ir cells in layer II and a second band in layers V-VI. There was no difference in the distribution of calbindin-ir neurons among visual areas at maturity.

Animals↗
PubMed1987

Inhibitory and stimulatory effects of dexamethasone and 1,25-dihydroxyvitamin D3 on chick intestinal calbindin-D28K and its mRNA.

The present study examined the interactions of the synthetic glucocorticoid, dexamethasone, with the regulation of chick intestinal calbindin-D28K (a 28,000 Da vitamin D-dependent calcium binding protein, CaBP) and its mRNA by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Dexamethasone (0-500 nmol) had a neutral impact on calbindin levels in the rachitic chick intestine when measured 12 h later. However, dexamethasone appeared to exert a significant, though modest, stimulatory influence upon calbindin-mRNA accumulation in the vitamin D-deficient (-D) intestine when measured 12 h after administration. 1,25(OH)2D3 also stimulated calbindin-mRNA accumulation in the -D chick intestine; half-maximal (ED50) doses were 1.1 nmol (7.6-fold) and 12.6 nmol (4.3-fold stimulation) for 1,25(OH)2D3 and dexamethasone respectively. In contrast, when both 1,25(OH)2D3 and dexamethasone were administered simultaneously, the stimulatory effect of 1,25(OH)2D3 (and that of the glucocorticoid) was lost in terms of calbindin and calbindin-mRNA accumulation. Dexamethasone treatment of vitamin D-replete (+D) chicks resulted in a depression of calbindin-mRNA accumulation; levels were depressed to baseline with 250 nmol/bird. Dexamethasone (1.25 mumol per day for 3 days) also induced an apparent 'down-regulation' of the 1,25(OH)2D3 receptor population in the -D chick intestine but failed to influence the binding of 1,25(OH)2D3 to its receptor in vitro. Taken collectively, these data indicate that glucocorticoids are able to influence the receptor-mediated action of 1,25(OH)2D3, possibly at the level of calbindin-D28K gene expression.

Animals↗
PubMed1993

Glutamate, GABA, calbindin-D28k and parvalbumin immunoreactivity in the pulvinar-lateralis posterior complex of the cat: relation to the projection to the Clare-Bishop area.

Neurons of the pulvinar-lateralis posterior complex (Pul-LP) containing glutamate (Glu) and GABA, as presumed neurotransmitters, and calbindin- D28k (calbindin) and parvalbumin (PV), as Ca-binding proteins, were identified in the cat by using immunohistochemical methods. In vibratome sections, neurons immunoreactive (IR) to each of the four antibodies were observed throughout the Pul-LP. In semithin sections, GABA-IR neurons were also PV-IR but not calbindin-IR and some of them also co-localized Glu. The Glu-IR neurons which were negative for GABA co-localized calbindin but not PV. The neurons of the Pul-LP projecting to the Clare-Bishop area (CB) in the suprasylvian gyrus were identified with a retrogradely transported tracer and the sections were then immunostained for Glu, GABA, calbindin and PV. Only Glu- and calbindin-IR neurons were retrogradely labeled. These results show that, if calbindin and PV have a Ca-binding role, the presumably excitatory Glu-IR neurons projecting to the CB are use calbindin whereas the presumably inhibitory GABA-IR neurons are intrinsic and use PV. This relationship implies that these proteins probably have other roles specifically related to the kind of agonist to be released at the neuron.

Animals↗
PubMed1988

Influence of peripheral and central targets on subpopulations of sensory neurons expressing calbindin immunoreactivity in the dorsal root ganglion of the chick embryo.

The influence of central and peripheral target tissues on the expression of calbindin D-28k by sensory neurons of the chick dorsal root ganglia was tested under various experimental conditions. Firstly, dorsal root ganglia of chick embryos were transplanted at two stages of development onto the chorioallantoic membrane of a host embryo for a period of 4 or 8 days. In dorsal root ganglia grafted at E12, 20% of the ganglion cell bodies were immunoreactive to calbindin 4 and 8 days later; the percentage of calbindin-immunostained neurons in grafted dorsal root ganglia was similar to that observed in control dorsal root ganglia of the same embryonic age (E16 or 20). In contrast, when grafted dorsal root ganglia were taken from a donor embryo at E8, no calbindin-immunoreactive neuron was found 4 or 8 days later. However, when dorsal root ganglia at E8 were cotransplanted with musculature cells, 14% of the grafted ganglion cell bodies were again immunoreactive to calbindin 4 or 8 days later. Secondly, peripheral targets of sensory neurons were suppressed by excision of one hindlimb. After excision at E6, virtually all the ipsilateral dorsal root ganglia cells were free of calbindin immunoreaction after 6 days of reincubation. In contrast, when the excision was performed at E11, calbindin was expressed in about 9% of the nerve cell bodies. Thirdly, central connections were destroyed by cauterization of the lumbosacral spinal cord at E6 or E11. Six days after deprivation of central connections, the percentage of calbindin-immunoreactive ganglion cells was the same as in control dorsal root ganglia of the same age.(ABSTRACT TRUNCATED AT 250 WORDS)

Allantois↗
PubMed1990

Calcium-binding proteins calbindin and parvalbumin in the superficial dorsal horn of the rat spinal cord.

Neurons containing the calcium-binding proteins, calbindin or parvalbumin, were studied by immunohistochemistry in the superficial dorsal horn of the rat spinal cord. Calbindin-containing cells were found in laminae I, II and III, being more abundant in laminae I and II. Some of the neurons in lamina I containing calbindin projected to the supraspinal area. Parvalbumin-containing neurons were mainly distributed in laminae IIi and III. Calbindin and parvalbumin were not detected in the same cells. Some 75% of the neurotensin-like immunoreactive neurons contained calbindin, which corresponded to 13% of the calbindin-containing neurons. Calbindin was sometimes found in the same cells with substance P, enkephalin or somatostatin but less frequently (44-46% of the peptide-containing neurons). Parvalbumin was not found together with these peptides. Electron microscopy showed that the immunoreactive products of calbindin or parvalbumin were mostly in the dendrites or cell bodies. Immunoreactive axon terminals were relatively few. In rhizotomized animals, neurons containing one of these proteins in laminae II and III were found to receive direct inputs of primary afferent fibers. These findings indicate that neurons containing these two proteins belong to different subpopulations of dorsal horn neurons. They may be important in primary afferent processing.

Animals↗
PubMed1997

Decrease in kidney calbindin-D 28kDa as a possible mechanism mediating cyclosporine A- and FK-506-induced calciuria and tubular mineralization.

The use of the immunosuppressant cyclosporine A (CsA) is limited by its adverse renal effects. Most recently, we reported that the drug markedly decreases the levels of the calcium-binding protein calbindin-D 28kDa in kidneys of male Wistar rats. In the present study, the potential relationship between drug-induced nephrotoxicity and the decrease in kidney calbindin-D 28kDa was investigated. Four groups of male Wistar rats were treated for 10 or 31 days with either the immunosuppressant CsA (50 mg/kg/day), FK-506 (5 mg/kg/day), rapamycin (5 mg/kg/day) or with the nonimmunosuppressive cyclosporine derivative 3'keto-[Bmt1]-[Val2]-CsA (SDZ PSC-833) (50 mg/kg/day), and the effects on calcium homeostasis, kidney histology and renal calbindin-D 28kDa were examined. Similar effects were found with CsA and FK-506; both drugs strongly reduced kidney calbindin-D 28kDa protein levels, increased urine calcium excretion, caused intratubular calcification, and induced basophilic tubules. In contrast, rapamycin and SDZ PSC-833 caused no decrease in renal calbindin-D 28kDa levels, no noticeable alterations in calcium metabolism, and no renal calcification. The results provide evidence for a link between decreased renal calbindin, increased calcium urine excretion, and intratubular kidney calcification. The present data show no correlation between the decrease in renal calbindin and the induction of basophilic tubules; however, it needs to be investigated if these apparently independent kidney effects may have a common origin upstream of calbindin expression.

Animals↗
PubMed2000

On the altered expression of tyrosine hydroxylase and calbindin-D 28kD immunoreactivities and viability of neurons in the ventral tegmental area of Tsai following injections of 6-hydroxydopamine in the medial forebrain bundle in the rat.

Calbindin-D 28kD is a calcium binding protein reported to protect neurons from degeneration by buffering intracellular calcium. It is expressed in midbrain dopaminergic neurons reported to be relatively resistant to degeneration in Parkinson's disease and certain of its animal models. Lesions of the nigrostriatal pathway produced in rats following injection of 6-hydroxydopamine result in a neurochemical profile similar to that seen in patients with Parkinson's disease. In the present study, brains were processed to exhibit tyrosine hydroxylase- and calbindin-D 28kD immunoreactivities in sections through the ventral mesencephalon at 3, 7, 10, 14 and 21 days after 6-hydroxydopamine had been injected into the medial forebrain bundle. Numbers of ventral mesencephalic calbindin-D 28kD immunoreactive neurons were significantly reduced ipsilateral to the lesions at 3 days post-lesion and, following slight recovery, remained significantly depleted through post-lesion day 21. The densities of calbindin-D 28kD and tyrosine hydroxylase immunoreactive neurons were different only at the 3 day post-lesion time point, when the apparent loss of calbindin-D 28 kD immunoreactive profiles was significantly greater. A lesion-induced increase in the proportion of neurons exhibiting both calbindin-D 28kD and tyrosine hydroxylase immunoreactivities, expected if calbindin-D 28kD is neuroprotective, was observed in the substantia nigra, pars compacta, but not in the ventral tegmental area. It is concluded that, while the observed losses of tyrosine hydroxylase and calbindin-D 28kD immunoreactivities do not necessarily reflect neuronal degeneration, they are not consistent with CB confering a neuroprotective advantage in the ventral tegmental area following 6-OHDA lesions as administered in this study.

Animals↗
PubMed2000

GABA(A) receptors on calbindin-immunoreactive myenteric neurons of guinea pig intestine.

These studies were carried out to characterize the properties of gamma-aminobutyric acidA (GABA(A)) receptors on guinea pig intestinal myenteric neurons maintained in primary culture. In addition, the type of neuron expressing GABA(A) receptors was identified using immunohistochemical methods. Whole-cell patch clamp recordings of currents elicited by GABA and acetylcholine (ACh) were obtained using pipettes containing Neurobiotin. After electrophysiological studies, neurons were processed for localization of calbindin-D28K-immunoreactivity (calbindin-ir). GABA (1 mM) and ACh (3 mM) caused inward currents in most cells tested. GABA currents were mimicked by muscimol (1-300 microM) and were blocked by bicuculline (10 microM) indicating that GABA was acting at GABA(A) receptors. GABA currents were associated with a conductance increase and a linear current/voltage relationship with a reversal potential of 1 +/- 1 mV (n = 5). Pentobarbital (PB, 3-1000 microM) and diazepam (DZP, 0.01-10 microM) potentiated GABA-induced currents. A maximum concentration of DZP (1 microM) increased GABA-induced currents 3.1 +/- 0.3 times while PB (1000 microM) increased GABA currents by 11 +/- 2 times. In outside-out patches, the amplitude of GABA-activated single-channel currents was linearly related to membrane potential with a single-channel conductance of 28.5 + 0.5 pS (n = 10). PB and DZP increased the open probability of GABA-induced single-channel currents. Neurons containing calbindin-ir were large, were isolated from other neurons and had GABA current amplitudes of -3.4 +/- 0.3 nA (n = 48). Neurons with weak or absent calbindin-ir were smaller, were localized in clusters of cells and had GABA-induced current amplitudes of -0.6 +/- 0.1 nA (n = 20). ACh-induced currents were smaller in calbindin-ir neurons (-0.7 +/- 0.1 nA) compared to weakly calbindin-ir neurons (-1.4 +/- 0.1 nA). These results indicate that myenteric calbindin-ir neurons express a high density of GABA(A) receptors. Cell size and location allow visual identification of neurons likely to contain calbindin-ir permitting targeted studies of the properties of these neurons.

Animals↗
PubMed2003

Intestinal and eggshell calbindin, and bone ash of laying hens as influenced by age and molting.

A series of trials was conducted in order to study the effects of age and molt on intestinal and eggshell gland (ESG) calbindin, and on bone ash. For this purpose an ELISA for chicken calbindin was developed. Age did not significantly affect duodenal or ESG calbindin. Bone ash increased (but not significantly in this study) from 8 to 16 months of age. During molt induction, egg laying was arrested, duodenal and ESG calbindin almost completely disappeared and ovary mass, plasma estradiol and total calcium (Ca) decreased markedly, whereas bone ash and body mass (BW) decreased moderately. During the non-laying period that followed the feed withdrawal period, duodenal and ESG calbindin remained low, whereas plasma estradiol and other estrogen-dependent variables, such as plasma total Ca and bone ash, increased slightly. At the onset of egg production following molting, duodenal and ESG calbindin levels were similar to pre molt level. Bone ash was higher than at the pre molt period. Body mass, small yellow follicles, ovary and oviduct mass and plasma estradiol were lower than their values prior to molt induction. Bone ash contents in the molted hens at the ages of 583 and 820 days were similar to or even slightly higher than those in the non-molted hens, whereas duodenal and ESG calbindin were not significantly different. These results suggest that the improvement of shell quality in the molted birds does not involve mechanisms associated with calbindin synthesis.

Aging↗