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PubMed2000

Decreased calbindin-D28k immunoreactivity in aged rat sympathetic pelvic ganglionic neurons.

The rat major pelvic ganglion contains the majority of sympathetic and parasympathetic postganglionic neurons that innervate the pelvic viscera. Previous studies have indicated that it is only the sympathetic population of this ganglion that is susceptible to age-associated changes. We have examined the distribution of the neuronal calcium binding proteins calbindin-D28k, calretinin and parvalbumin by immunohistochemistry in young adult and aged rats and have discovered that calbindin-D28k is only present in the sympathetic neurons (identified by tyrosine hydroxylase immunostaining) and not in parasympathetic neurons (identified by VIP immunostaining). In the aged rats the number of calbindin-immunoreactive sympathetic neurons of the major pelvic ganglion was dramatically reduced. Calretinin and parvalbumin-immunoreactivity was present at a lower level of fluorescence than that of calbindin immunoreactivity in all the neurons of the major pelvic ganglion and this level was unchanged in aged rats. Thus we suggest that the decline of intracellular calbindin D28k levels may lead to impaired calcium buffering capacity which might be a contributory factor in the age-associated attrition of pelvic sympathetic neurons.

Aging↗
PubMed2002

Changes of calretinin, calbindin D28K and parvalbumin-immunoreactive neurons in the superficial layers of the hamster superior colliculus following monocular enucleation.

We studied the effects of monocular enucleation on the patterned distribution of calretinin-, calbindin D28K- and parvalbumin-immunoreactive (IR) neurons in the superficial layers of the hamster superior colliculus (SC). The calcium-binding proteins were localized using antibody immunocytochemistry. Almost complete depletion of the calretinin-IR fibers in the superficial layers of the contralateral SC was found following unilateral enucleation. Quantitative analysis showed that on the experimental side of the SC, an enormous number of calretinin-IR cells newly appeared (716%). On the experimental side of the SC, the number of parvalbumin-IR cells also increased (32%). By contrast, on the experimental side of the SC, the number of calbindin D28K-IR cells exhibited a reduction (43%). Two-color immunofluorescence revealed that none of the newly appeared calretinin-IR cells were labeled with antibodies to calbindin D28K or parvalbumin. The present results demonstrate that retinal projection may control the activity of the expression of these calcium-binding proteins in the hamster SC but in different manners. The results also show that the patterned change of calretinin and parvalbumin in the hamster SC is comparable with other animals, but the change of calbindin D28K is not identical.

Animals↗
PubMed2002

Differential changes of calcium binding proteins in the rat striatum after kainic acid-induced seizure.

It has been suggested that calcium binding proteins protect against Ca2+ overload, thus rendering neurons more resistant against excitotoxicity. The influence of kainic acid, which induces status epilepticus, on the expressions of calbindin D28k, parvalbumin and calretinin was examined in the rat striatum by immunohistochemistry and microdensitometry. At 1, 3 and 6 days after kainic acid-induced seizure, the number of calretinin-positive neurons in the striatum was significantly lower than in control rats. However, no significant difference was observed in the number of calbindin D28k- and parvalbumin-positive neurons in control and seizure rats. At 1, 3 and 6 days after seizure the optical densities of calretinin- and parvalbumin-positive neurons in the striatum were significantly lower than in control rats. Our finding concerning the selective loss of calretinin-positive neurons in seizure groups suggests that calcium binding proteins in the striatum have differential vulnerabilities to kainic acid-induced seizure.

Animals↗
PubMed2000

Neurodegenerative and morphogenic changes in a mouse model of temporal lobe epilepsy do not depend on the expression of the calcium-binding proteins parvalbumin, calbindin, or calretinin.

The functional role of the calcium-binding proteins parvalbumin, calretinin, and calbindin D-28k for epileptogenesis and long-term seizure-related alterations of the hippocampal formation was assessed in single- and double-knockout mice, using a kainate model of mesial temporal lobe epilepsy. The effects of a unilateral intrahippocampal injection of kainic acid were assessed at one day, 30 days, and four months post-injection, using various markers of GABAergic interneurons (GABA-transporter type 1, GABA(A)-receptor alpha1 subunit, calretinin, calbindin D-28k, somatostatin, and neuropeptide Y). Parvalbumin-deficient, parvalbumin/calbindin-deficient, and parvalbumin/calretinin-deficient mice exhibited no difference in cytoarchitecture of the hippocampal formation and in the number, distribution, or morphology of interneurons compared to wild-type mice. Likewise, mutant mice were not more vulnerable to acute kainate-induced excitotoxicity or to long-term effects of recurrent focal seizures, and exhibited the same pattern of neurochemical alterations (e.g., bilateral induction of neuropeptide Y in granule cells) and morphogenic changes (enlargement and dispersion of dentate gyrus granule cells) as wild-type animals. Quantification of interneurons revealed no significant difference in neuronal vulnerability among the genotypes.These results indicate that the calcium-binding proteins investigated here are not essential for determining the neurochemical phenotype of interneurons. Furthermore, they are not protective against kainate-induced excitotoxicity in this model, and do not appear to modulate the overall level of excitability of the hippocampus. Finally, seizure-induced changes in gene expression in granule cells, which normally express high levels of calcium-binding proteins, apparently were not affected by the gene deletions analysed.

Animals↗
PubMed2000

A group of cortical interneurons expressing mu-opioid receptor-like immunoreactivity: a double immunofluorescence study in the rat cerebral cortex.

mu-Opioid receptor-expressing neurons in the rat cerebral neocortex were characterized by an immunolabeling method with an antibody to a carboxyl terminal portion of the receptor. They were small, bipolar, vertically elongated, non-pyramidal neurons, and scattered mainly in layers II-IV. We examined chemical characteristics of mu-opioid receptor-expressing neocortical neurons by the double immunofluorescence method. Almost all neuronal cell bodies expressing mu-opioid receptor-like immunoreactivity showed immunoreactivity for GABA, suggesting that they were cortical inhibitory interneurons. mu-Opioid receptor-immunoreactive neurons were further studied by the double staining method with markers for the subgroups of cortical GABAergic neurons. Immunoreactivities for vasoactive intestinal polypeptide, corticotropin releasing factor, choline acetyltransferase, calretinin and cholecystokinin were found in 92, 79, 67, 35 and 35% of mu-opioid receptor-immunoreactive cortical neurons, respectively. In contrast, less than 10% of mu-opioid receptor-immunoreactive neurons showed immunoreactivity for parvalbumin, calbindin, somatostatin, neuropeptide Y or nitric oxide synthase. Moreover, mu-opioid receptor-immunoreactive neurons very frequently exhibited preproenkephalin immunoreactivity, but not preprodynorphin immunoreactivity. The present results indicate that mu-opioid receptor-expressing neurons belong to a distinct subgroup of neocortical GABAergic neurons, because vasoactive intestinal polypeptide, corticotropin releasing factor, choline acetyltransferase, calretinin and cholecystokinin have often been reported to coexist with one another in single neocortical neurons. Methionine-enkephalin, which is a major product of the preproenkephalin gene, is known to be one of the most potent endogenous ligands for mu-opioid receptor. Thus, the expression of mu-opioid receptor in preproenkephalin-producing neurons suggested that mu-opioid receptor serves as an autoreceptor for the subpopulation of GABAergic interneurons at a single-neuron or population level.

Animals↗
PubMed2000

Striatal cells containing aromatic L-amino acid decarboxylase: an immunohistochemical comparison with other classes of striatal neurons.

In a previous study, we described a population of striatal cells in the rat brain containing aromatic L-amino acid decarboxylase, the enzyme involved in the conversion of L-DOPA into dopamine. We have also presented evidence that these cells produce dopamine in the presence of exogenous L-DOPA. In this paper, we further characterize these striatal aromatic L-amino acid decarboxylase-containing cells in order to determine whether they form a subclass of one of the known categories of striatal neurons or if they represent a novel cell type. Using immunohistochemical methods, we compared the morphology and distribution of the aromatic L-amino acid decarboxylase-immunolabeled cells with those of other classes of striatal neurons. Our results show that both the morphology and distribution of aromatic L-amino acid decarboxylase-immunolabeled cells are very distinctive and do not resemble those of cells labeled for other striatal neuronal markers. Double-labeling procedures revealed that aromatic L-amino acid decarboxylase cells do not co-localize somatostatin or parvalbumin, and only a very small percentage of them co-localize calretinin. However, the population of aromatic L-amino acid decarboxylase cells label intensely for GABA.Overall, our results suggest that these aromatic L-amino acid decarboxylase-containing cells represent a class of striatal GABAergic neurons not described previously.

Animals↗
PubMed2001

The spiny rat Proechimys guyannensis as model of resistance to epilepsy: chemical characterization of hippocampal cell populations and pilocarpine-induced changes.

At variance with pilocarpine-induced epilepsy in the laboratory rat, pilocarpine administration to the tropical rodent Proechimys guyannensis (casiragua) elicited an acute seizure that did not develop in long-lasting status epilepticus and was not followed by spontaneous seizures up to 30 days, when the hippocampus was investigated in treated and control animals. Nissl staining revealed in Proechimys a highly developed hippocampus, with thick hippocampal commissures and continuity of the rostral dentate gyri at the midline. Immunohistochemistry was used to study calbindin, parvalbumin, calretinin, GABA, glutamic acid decarboxylase, and nitric oxide synthase expression. The latter was also investigated with NADPH-diaphorase histochemistry. Cell counts and densitometric evaluation with image analysis were performed. Differences, such as low calbindin immunoreactivity confined to some pyramidal cells, were found in the normal Proechimys hippocampus compared to the laboratory rat. In pilocarpine-treated casiraguas, stereological cell counts in Nissl-stained sections did not reveal significant neuronal loss in hippocampal subfields, where the examined markers exhibited instead striking changes. Calbindin was induced in pyramidal and granule cells and interneuron subsets. The number of parvalbumin- or nitric oxide synthase-containing interneurons and their staining intensity were significantly increased. Glutamic acid decarboxylase(67)-immunoreactive interneurons increased markedly in the hilus and decreased in the CA1 pyramidal layer. The number and staining intensity of calretinin-immunoreactive pyramidal cells and interneurons were significantly reduced. These findings provide the first description of the Proechimys hippocampus and reveal marked long-term variations in protein expression after an epileptic insult, which could reflect adaptive changes in functional hippocampal circuits implicated in resistance to limbic epilepsy.

Animals↗
PubMed2001

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↗
PubMed2002

Extending the cerebellar Lugaro cell class.

We describe here, in Golgi-impregnated rat cerebellar cortex, a new group of large granular layer neurons. These cells have a globular soma located at variable depths in the granular layer, and three to four long radiating dendrites coursing through the three layers of the cortex. The axon projects more or less directly into the molecular layer, where it expands in a local plexus of oblique and tortuous thick collaterals ascending through the major part of the layer. Interestingly, the axons of several of these cells give off a collateral that courses for a long distance in the transverse direction, just above the Purkinje cell somata, parallel to the parallel fibers. While the granular layer location and the polymorphous somato-dendritic pattern of these cells is reminiscent of that of Golgi cells, their axonal pattern is clearly of the same type as that of another large granular layer interneuron, the Lugaro cell. Moreover, double anti-calretinin and anti-calbindin immunolabellings show that Lugaro cells as well as some globular somata dispersed in the granular layer are both calretinin-positive and in close apposition with numerous calbindin-positive varicosities of Purkinje cell axon recurrent collaterals. These latter are known from previous ultrastructural studies to be pre-synaptic to Lugaro cells. The common granular layer location and calretinin labelling, the striking similarity in axonal projection pattern, and the important common recurrent afferentation by Purkinje cell axons strongly argue in favor of the classification of these globular interneurons as a subgroup of a widened Lugaro cell type.

Animals↗
PubMed1998

Endogenous neurotrophin-3 supports the survival of a subpopulation of sensory neurons in neonatal rat.

Neurotrophin-3 promotes the differentiation and supports the survival of neuroblasts derived from the neural crest in early development. Neurotrophin-3 also plays an important role in the differentiation and survival of a subpopulation of large sensory neurons after their axons arrive at their targets. Proprioception and mechanoception are lost after gene deletion of neurotrophin-3 or its high-affinity receptor, TrkC. However, the function of neurotrophin-3 during late development and in mature animals is not clear. We have used an antiserum, specific for neurotrophin-3, to neutralize endogenous neurotrophin-3 in postnatal rats to determine its role in late sensory neuron development. Administration of the antiserum for a period of two weeks, but not one week, resulted in a 20% reduction in the number of primary sensory neurons in the dorsal root ganglia and a 19% reduction in the number of myelinated axons in the saphenous nerve. The size distribution histogram also indicated that a subpopulation of large neurons was lost by the neurotrophin-3 antiserum treatment. This neuronal loss was accompanied by reduced cell soma sizes and weights of the ganglia. Immunoreactivities for calbindin and calretinin were reduced in the trigeminal and dorsal root ganglia and nerve fibres surrounding whisker hair follicles. The number of Merkel cells in touch domes labelled with quinacrine and the number of parvalbumin-immunoreactive neurons in the dorsal root ganglia were significantly reduced by the antibody treatment. In contrast, the number of muscle spindles in the gastrocnemius muscle is not reduced by the neurotrophin-3 antiserum. Together, these results indicate that a subpopulation of primary sensory neurons in the neonatal rat requires neurotrophin-3 for their survival and expression of calcium binding proteins. In addition, Merkel cells in touch domes also require neurotrophin-3 for their survival. Thus, endogenous neurotrophin-3 in neonatal rats is critical for the survival and function of a subpopulation of primary sensory neurons and Merkel cells.

Animals↗
PubMed1999

Localization of calcium-binding proteins and GABA transporter (GAT-1) messenger RNA in the human subthalamic nucleus.

The distribution of messenger RNA encoding the human GAT-1 (a high-affinity GABA transporter) was investigated in the subthalamic nucleus of 10 neurologically normal human post mortem cases. Further, the distribution of messenger RNA and protein encoding the three neuronally expressed calcium-binding proteins (calbindin D28k, parvalbumin and calretinin) was similarly investigated using in situ hybridization and immunohistochemical techniques. Cellular sites of calbindin D28k, parvalbumin, calretinin and GAT-1 messenger RNA expression were localized using human-specific oligonucleotide probes radiolabelled with [35S]dATP. Sites of protein localization were visualized using specific anti-calbindin D28k, anti-parvalbumin and anti-calretinin antisera. Examination of emulsion-coated tissue sections processed for in situ hybridization revealed an intense signal for GAT-1 messenger RNA within the human subthalamic nucleus, indeed the majority of Methylene Blue-counterstained cells were enriched in this transcript. Further, a marked heterogeneity was noted with regard to the expression of the messenger RNA's encoding the three calcium-binding proteins; this elliptical nucleus was highly enriched in parvalbumin messenger RNA-positive neurons and calretinin mRNA-positive cells but not calbindin messenger RNA-positive cells. Indeed, only an occasional calbindin messenger RNA-positive cell was detected within the mediolateral extent of the nucleus. In marked contrast, numerous parvalbumin messenger RNA-positive cells and calretinin messenger RNA-positive cells were detected and they were topographically distributed; parvalbumin messenger RNA-positive cells were highly enriched in the dorsal subthalamic nucleus extending mediolaterally; calretinin messenger RNA-positive cells were more enriched ventrally although some degree of overlap was apparent. Computer-assisted analysis of the average cross-sectional somatic area of parvalbumin, calretinin and GAT-1 messenger RNA-positive neurons revealed them all to be in the range of 300 microm2. The unique patterns of calcium-binding protein gene expression were similarly reflected at the protein level; an abundance of parvalbumin- and calretinin-immunopositive neurons were observed whereas only occasional intensely-labelled calbindin-immunopositive fibres were seen, no calbindin-immunopositive cells were detected. Single and double labelling studies show that parvalbumin-immunopositive neurons were mainly localized in the dorsal region of the nucleus, and calretinin-immunopositive neurons were mainly localized in the ventral region although there was overlap with double-labelled neurons located in the middle and dorsal regions. The significance of these findings, in particular the expression of GAT-1, a high-affinity GABA uptake protein, for basal ganglia signalling is discussed.

Basal Ganglia↗
PubMed1999

Calcium-binding protein immunoreactivity delineates the intralaminar nuclei of the thalamus in the human brain.

Immunohistochemical studies have shown that the three calcium-binding proteins (calbindin-D28k, calretinin and parvalbumin) are heterogeneously distributed in the mammalian brain and are useful for delineating nuclear boundaries. We have investigated the distribution of the three calcium-binding proteins in the human thalamus in order to assist in the delineation of the equivocal nuclear boundaries of the intralaminar nuclei of the thalamus. The results show that each of the "functional" nuclear complexes in the human thalamus demonstrates a characteristic pattern of calcium-binding protein immunoreactivity. In particular, the intralaminar nuclei are characterized by a unique combination of calcium-binding protein staining which clearly delineates the component nuclei in this complex from the other nuclei of the human thalamus. The anterior group of intralaminar nuclei (central lateral nucleus, paracentral nucleus and central medial nucleus) showed intense staining for both calbindin-D28k and calretinin. By contrast, the posterior group of intralaminar nuclei (centre median nucleus and parafascicular nucleus) showed a complementary pattern of staining; the centre median nucleus showed immunoreactivity only for one calcium-binding protein, parvalbumin, while the parafascicular nucleus showed immunoreactivity for both calbindin-D28k and calretinin. No other nucleus in the human thalamus showed these particular combinations of calcium-binding protein staining. Since the intralaminar nuclei also have unique topographically organized connectional affiliations with both the cerebral cortex and the basal ganglia, these results suggest that the calcium-binding proteins may play an important role in the influence of the intralaminar nuclei on interactions between the cerebral cortex and the basal ganglia.

Adult↗
PubMed1999

Developmental expression of calretinin immunoreactivity in the human retina and a comparison with two other EF-hand calcium binding proteins.

This paper reports the localization pattern of calretinin, a calcium-binding protein, in the human retina during development, as studied by immunohistochemistry. A comparison is made of the cellular distribution of calretinin with two other calcium-binding proteins, calbindin and parvalbumin, recently reported by us in the human retina, and by parallel labeling with both antisera in the same tissues. At 11-12 weeks of gestation, calretinin immunoreactivity was expressed in many prospective ganglion cells of the central inner neuroblastic zone. At 16-17 weeks of gestation, the immunoreactivity was localized in the ganglion cell layer, inner plexiform layer, and in most differentiated amacrine, horizontal and cone cells located in the central (1-2 mm temporal from optic disc) to midperipheral parts of the retina. By midgestation (20-21 weeks), calretinin immunoreactivity was strongly developed in the cone photoreceptors. Parallel labeling with calbindin and parvalbumin antisera revealed that the calretinin-positive horizontal cells were somewhat smaller and less frequent and less intense than the calbindin- and parvalbumin-positive counterparts, at 16-21 weeks of gestation. No horizontal cells were calretinin immunopositive in the postnatal (four-month-old infant) and adult retinas examined. Also, at both stages, a few bipolar and cone cells were weakly immunoreactive. These observations suggest a critical role for calretinin in the development and maturation of a select class of horizontal cells. The widespread expression of immunoreactivity in the early ganglion cells indicates that calretinin may be involved in their differentiation. The weak immunoreactivity pattern noted in the adult photoreceptor and bipolar cells, and an apparent lack of immunoreactivity in the mature horizontal cells, tends to indicate that, unlike calbindin and parvalbumin, calretinin plays little role in the transport and physiological buffering of Ca2+ in these neurons of the human retina. It appears, however, that calretinin is predominantly involved in both processes in amacrine cells.

Calbindin 2↗
PubMed1999

Subfield- and layer-specific changes in parvalbumin, calretinin and calbindin-D28K immunoreactivity in the entorhinal cortex in Alzheimer's disease.

The entorhinal cortex, which is involved in neural systems related to memory, is selectively degenerated in early Alzheimer's disease. Here, we examined neuropathological changes in the eight entorhinal subfields in post mortem Alzheimer's disease subjects using Thionin and Bielschowsky stains and parvalbumin, calretinin and calbindin-D28k immunohistochemistry. Both histological stains revealed the most dramatic cell loss and neurofibrillary tangle formation to be in layers II and V of the lateral, intermediate and caudal subfields. In accordance, immunohistochemical staining showed that neurons and fibres that contain calcium-binding proteins were also more frequently altered in these subfields than in the rostromedial subfields. Detailed analysis further revealed that non-principal cells containing parvalbumin or calbindin-D28k showed morphological alterations early in the entorhinal pathology of Alzheimer's disease, whereas non-principal neurons containing calretinin were better preserved even in Alzheimer's disease patients with severe entorhinal pathology. The degeneration of parvalbumin-immunoreactive neurons and basket-like networks and calbindin-positive non-principal neurons was observed mainly in layer II, where the calretinin-positive non-principal neurons formed aggregates especially at late stages of the disease. The pyramidal-shaped neurons containing either calretinin or calbindin-D28k were often preserved, although morphological alterations were observed. Our findings indicate that specific subfields of the entorhinal cortex involving neurons that contain distinct calcium-binding proteins are differentially vulnerable in Alzheimer's disease. This could have an impact on the topographically organized inputs and outputs of the entorhinal cortex in Alzheimer's patients.

Aged↗
PubMed1999

Cannabinoid CB1 receptors are localized primarily on cholecystokinin-containing GABAergic interneurons in the rat hippocampal formation.

Localization of cannabinoid CB 1 receptors on GABAergic interneurons in the rat hippocampal formation was studied by double-labeling immunohistochemistry with confocal microscopy. Virtually all CB1-immunoreactive neurons (95%) are GABAergic. CB 1 fluorescence showed a punctate pattern. In contrast, the GABA fluorescence was distributed homogeneously, suggesting that while CB 1 receptors and GABA exist in the same cells they are not localized in the same subcellular compartments. Although virtually all CB1 neurons were GABAergic, many GABAergic neurons did not contain CB1 receptors. GABAergic interneurons in the hippocampal formation can be further divided into subpopulations with distinct connections and functions, using cell markers such as neuropeptides and calcium binding proteins. CB1 receptors were highly co-localized with cholecystokinin and partially co-localized with calretinin and calbindin, but not with parvalbumin. This suggests that cannabinoids may modulate GABAergic neurotransmission at the synapses on the soma and at synapses on the proximal dendrites of the principal neurons, as well as at synapses on other GABAergic interneurons.

Animals↗
PubMed1999

Adrenergic alpha2C-receptors reside in rat striatal GABAergic projection neurons: comparison of radioligand binding and immunohistochemistry.

We have investigated the distribution of alpha2c-adrenergic receptors in the rat striatum and characterized the striatal neuron types expressing these receptors. Sequential double-labelled immunocytochemistry was performed with a polyclonal antibody against rat alpha2c-adrenoceptors and antibodies against GABA, Calbindin-D28k, parvalbumin and calretinin. The subregional distribution of alpha2c-adrenoceptor binding sites in the striatum was also quantitatively investigated using selective radioligands. Almost all lightly stained striatal GABAergic neurons, with the morphological characteristics of medium-sized spiny projection neurons (94% of GABAergic cells counted), contained alpha2c-adrenoceptor-immunoreactive structures. Intensely labelled GABAergic inteneurons (6%) were devoid of alpha2c-adrenoceptor immunoreactivity. The co-localization of calbindin- and alpha2c-adrenoceptor immunoreactivity in the majority of the cells confirmed the presence of alpha2c-adrenoceptors in the population of medium-sized spiny neurons. Furthermore, the alpha2c-adrenoceptor/calbindin double-labelling disclosed the existence of three neuronal subsets in the matrix compartment of the striatum: a large proportion (83%) of double-labelled neurons, a population of neurons (8%) that exhibited only alpha2c-adrenoceptor immunoreactivity without calbindin immunoreactivity, and a population of neurons (9%) immunoreactive for calbindin, but lacking alpha2c-adrenoceptors. In addition, alpha2c-adrenoceptor immunolabelled neurons were observed in calbindin-free striatal patches. Parvalbumin- and calretinin-positive neurons never displayed alpha2c-adrenoceptor immunoreactivity, confirming that striatal GABAergic interneurons are devoid of alpha2c-adrenoceptors. The present findings indicate that alpha2c-adrenoceptors are localized in GABAergic medium-sized spiny projection neurons but not in interneurons of the rat striatum, and that they may modulate both the direct and indirect pathways of the basal ganglia, as well as participate in the regulation of mesencephalic dopaminergic neurons.

Adrenergic alpha-Antagonists↗
PubMed2000

Changes in the distribution and connectivity of interneurons in the epileptic human dentate gyrus.

The distribution, size, dendritic morphology and synaptic connections of calbindin-, calretinin- and substance P receptor-positive interneurons and pathways have been examined in control and epileptic human dentate gyrus. In the epileptic dentate gyrus, calbindin-containing interneurons are preserved, but their dendrites become elongated and spiny, and several cell bodies appear hypertrophic. The relative laminar distribution of calretinin-containing cells did not change, but their number was considerably reduced. The calretinin-positive axonal bundle at the top of the granule cell layer originating from the supramammillary nucleus expanded, forming a dense network in the entire width of the stratum moleculare. Substance P receptor-immunopositive cells were partially lost in epileptic samples, and in addition, the laminar distribution and dendritic morphology of the surviving cells differed considerably from the controls. In the control human dentate gyrus, the majority of substance P receptor-positive cells can be seen in the hilus, while most are present in the stratum moleculare in the epileptic tissue. Their synaptic input is also changed. The extent of individual pathological abnormalities correlates with each other in most cases. Our data suggest, that although a large proportion of inhibitory interneurons are preserved in the epileptic human dentate gyrus, their distribution, morphology and synaptic connections differ from controls. These functional alterations of inhibitory circuits in the dentate gyrus are likely to be compensatory changes with a role to balance the enhanced excitatory input in the region.

Adolescent↗
PubMed1996

The calcium binding protein calretinin is a selective marker for malignant pleural mesotheliomas of the epithelial type.

In a series of 23 cases of mesothelioma of either the epithelial, sarcomatoid or the mixed type, the expression of three calcium-binding proteins (calretinin, parvalbumin and calbindin-D28k) was studied using immunohistochemical techniques on paraffin sections. The results show that calretinin is expressed in mesotheliomas of the epithelial type (papillary, adenomatous or solid) and by the epithelial component of the mixed tumours. The immunohistochemical reaction is specific and reproducible. The tissues of the pulmonary parenchyma and of the pleura are negative for calretinin except for the rare fibroblasts and some skeletal muscle fibres situated in the interstices of, or near the epithelial tumour mass. The sarcomatoid mesotheliomas and the sarcomatoid component of the mixed tumours do not express calretinin. Parvalbumin and calbindin-D28k are expressed neither in mesotheliomas nor in normal lung tissue. Primary adenocarcinomas of the lung are negative for all three calcium binding proteins cited. Thus, calretinin seems to represent a selective marker for mesotheliomas of the epithelial type and allows their differentiation from metastases of lung adenocarcinomas.

Adenocarcinoma↗