A novel epitope expressed on the surface of developing and mature astrocytes.

Plasmalemmal fractions from cultured astrocytes have been used as the immunogen in generating a monoclonal antibody, termed 8C10, which binds to the surface of cultured astrocytes of the rat. 8C10 immunoreactivity is present on the membrane surface of cultured type 1 astrocytes, type 2 astrocytes, oligodendrocytes, meningeal cells, and 02A progenitor cells, and it persists after aldehyde fixation. The antibody also stains aldehyde-fixed central nervous system, in a pattern which suggests that the plasma membranes of fine astrocytic processes in adult neuropil express the epitope. Astrocytic perikarya and processes in white matter are also stained, but there is no immunoreactivity present in neuronal processes or perikarya. Astrocytic processes in developing cerebellar cortex are stained at postnatal ages when some of these processes are guiding the migration of neuronal perikarya.     

Expression of amyloid precursor protein-like molecule in astroglial cells of the subventricular zone and rostral migratory stream of the adult rat forebrain

In adult mammals, new neurons in the subventricular zone (SVZ) of the lateral ventricle (LV) migrate tangentially through the rostral migratory stream (RMS) to the olfactory bulb (OB), where they mature into local interneurons. Using a monoclonal antibody for the beta-amyloid precursor protein (APP) (mAb 22C11), which is specific for the amino-terminal region of the secreted form of APP and recognizes all APP isoforms and APP-related proteins, immunoreactivity was detected in specific subpopulations of cells in the SVZ and RMS of the adult rat forebrain. In the SVZ, APP-like immunoreactivity was detected in the ependymal cells lining the LV and some of the subependymal cells. The latter were regarded as astrocytes, because they were positive for the glial markers, S-100 protein (S-100) and glial fibrillary acidic protein (GFAP). APP-like immunoreactive astrocytes exhibited strong labelling of the perinuclear cytoplasm and often possessed a long, fine process similar to that found with radial glia. The process extended to an APP-like immunoreactive meshwork in the RMS that consisted of cytoplasmic processes of astrocytes forming 'glial tubes'. Double-immunofluorescent labelling with a highly polysialylated neural cell adhesion molecule (PSA-NCAM) confirmed that the APP-like immunoreactive astrocytes in the SVZ and meshwork in the RMS made close contact with PSA-NCAM-immunopositive neuroblasts, suggesting an interaction between APP-containing cells and neuroblasts. This region of the adult brain is a useful in vivo model to investigate the role of APP in neurogenesis.     

CD44 expression in tuberous sclerosis.

CD44, a cell adhesion molecule, mediates cell-cell and cell-matrix interactions. In the central nervous system, CD44 is expressed in astrocytic processes, predominantly in white matter and subpial regions, suggesting its involvement in the maintenance of a stable central nervous system cytoarchitecture. In this study, we investigated immunohistochemically the expression of CD44 and glial fibrillary acidic protein in neurosurgically resected specimens of patients with or without tuberous sclerosis. In controls, CD44 immunoreactivity was noted in the processes of astrocytes close to blood vessels and subpial cortex. Glial fibrillary acidic protein immunoreactivity was noted in both cell bodies and cytoplasmic processes of astrocytes in white matter. In tubers, CD44 antigen was also noted in the processes of astrocytes close to blood vessels and pial surface, and in abundance in the network of astrocyte processes. Moreover, CD44 antigen showed immunoreactive halos around balloon cells in tubers and around tumor cells in subependymal lesions. Glial fibrillary acidic protein antigen was noted in both cell bodies and cytoplasmic processes of some balloon cells in tubers, but not in tumor cells. In Western blot analyses, the CD44 immunoreactive band was more intense in tubers or subependymal giant-cell tumors than in control tissue. This increase in CD44 antigen seemed to correlate with the degree of astrogliosis. Immunoreactivity surrounding the cell surfaces of balloon or tumor cells suggests that the clustering of these cells may be due to the expression of CD44. Glial fibrillary acidic protein immunoreactive band was detected in tubers, but not in subependymal giant cell tumors.     

Cellular and regional expression of glutamate dehydrogenase in the rat nervous system: non-radioactive in situ hybridization and comparative immunocytochemistry.

In the central nervous system glutamate dehydrogenase appears to be strongly involved in the metabolism of transmitter glutamate and plays a role in the pathogenesis of neurodegenerative disorders. In order to identify unequivocally the neural cell types expressing this enzyme, non-radioactive in situ hybridization, using a complementary RNA probe and oligonucleotide probes, was applied to sections of the rat central nervous system and, for comparison with peripheral neural cells, to cervical spinal ganglia. The results were complemented by immunocytochemical studies using a polyclonal antibody against purified glutamate dehydrodenase. Glutamate dehydrogenase messenger RNA was detectable at varying amounts in neurons and glial cells (i.e. astrocytes, oligodendrocytes, Bergmann glia, ependymal cells, epithelial cells of the plexus choroideus) throughout the central nervous system and in neurons and satellite cells of spinal ganglia. In some neuronal populations (e.g., pyramidal cells of the hippocampus, motoneurons of the spinal cord and spinal ganglia neurons) messenger RNA-labelling was higher than in other central nervous system neurons. This is remarkable because the immunostaining of neurons in the central nervous system regions studied was at best weak, whereas a predominantly high level of immunoreactivity was detected in astrocytes (and Bergmann glia). Thus, in neurons of the central nervous system, the detected levels of glutamate dehydrogenase messenger RNA and protein seem to be at variance whereas in peripheral neurons of spinal ganglia both in situ hybridization labelling and immunostaining are intense.     

Glial cell differentiation in neuron-free and neuron-rich regions

Summary The development of the human fetal hippocampus and dentate gyros has been studied immunocytochemically. The first glial cells to appear are vimentin-positive radial glial cells. A gradual transition from vimentin to glial fibrillary acidic protein (GFAP) reactivity in the radial glial cells occurs at week 8. The GFAP-positive radial glial cells transform into astrocytes from week 14. A population of small S-100-positive somata which morphologically and spatially are distinct from GFAP-positive radial glial cells and their transformed progeny, are found as early as week 9.5 in the hippocampus during the period of peak neurogenesis. The well-defined immunoreactivity of the morphologically homogenous cell subpopulation for S-100 protein, which has been used as an astrocytic marker in the adult hippocampus, indicates that astrocytes may differentiate at very early gestational ages in human fetuses. The S-100-positive astrocytes are thought to be derived from ventricular zone cells, which at the time of their appearance do not express any of the applied astrocytic markers (S-100, GFAP, vimentin). It is suggested that the S-100-positive astrocytic cell population interacts with the first incoming projection fibers, so modulating the pattern of connectivity.     

Distribution of insulin receptor-like immunoreactivity in the rat forebrain

Previous studies have suggested that insulin may play a role in the hormonal regulation of neurotransmitter metabolisms within the central nervous system. In order to provide additional information to support this hypothesis, we examined the distribution of insulin receptors within the forebrain of adult male rats. Insulin receptors were localized by immunocytochemistry, using an antibody directed against the carboxy-terminus of the beta-subunit of the insulin receptor. The antibody specificity was tested by immunoprecipitation of brain insulin receptors with antiserum and the purity of the receptor-antibody preparation was determined using hormone binding-assays with radiolabeled insulin and insulin-like growth factor-l. Insulin receptor-like immunoreactivity was found in a widespread, but selective, distribution on neurons throughout the rat forebrain. Double-labeling with glial fibrillary acidic protein did not demonstrate any detectable insulin receptor-like immunoreactivity on glial cells. Areas with the highest density of insulin receptor-like immunoreactivity were found in the olfactory bulbs, hypothalamus and median eminence, medial habenula, subthalamic nucleus, subfornical organ, CA 1/2 pyramidal cell layer of the hippocampus and piriform cortex. Double-staining of hypothalamic sections with somatostatin and vasopressin antisera revealed insulin receptor-like immunoreactivity on a subpopulation of somatostatin neurons in the periventricular region and on vasopressin neurons in the supraoptic nucleus. A moderately dense insulin receptor-like immunoreactivity was observed in layers II-IV of cerebral cortex, medial amygdala, reticular thalamic nucleus, zona incerta, and preoptic and septal regions, whereas a low density of insulin receptor-like immunoreactive neurons was found in basolateral amygdala and most thalamic regions. The basal ganglia and most parts of the thalamus were almost devoid of insulin receptor-like immunoreactivity. Our findings provide morphological support for a direct action of insulin on selected regions of the rat forebrain and suggest that the insulin receptor may modulate synaptic transmission or the release of neurotransmitters and peptide hormones in the CNS.     

Effects of erythropoietin on glial cell development; oligodendrocyte maturation and astrocyte proliferation

We investigated the effects of erythropoietin (Epo) in glial cell development, especially the maturation of late stage immature oligodendrocytes and the proliferation of astrocytes. Epo mRNA level in oligodendrocytes was much more prominent than those in neurons or astrocytes, which were the same as those in the young adult kidney, while Epo receptor (Epo-R) mRNA level were almost the same among neural cells, kidney and liver tissues. On immunohistochemical examination, Epo-R expression was also detected in O4-positive immature oligodendrocytes and glial fibrillary acidic protein positive astrocytes. These results suggested that types of both glial cells are responsive to Epo. The numbers of mature oligodendrocytes, which are characterized by myelin basic protein and process development, were increased by treatment with recombinant human Epo (rhEpo) (0.001-0.1 U/ml). The maturation of oligodendrocytes was also enhanced by coculture with astrocytes in vitro. However, when mixed cultured cells (oligodendrocytes+astrocytes) were treated with anti-Epo antibody and/or soluble Epo-R, the differentiation of oligodendrocytes was partially inhibited. Interestingly, high dose rhEpo (1, 3, 10 U/ml) markedly enhanced the proliferation of astrocytes. These results suggested that Epo not only promotes the differentiation and/or maturation in oligodendrocytes, but also enhances the proliferation of astrocytes. It is generally accepted that astrocytes produce Epo, and therefore Epo might act on astrocytes in an autocrine manner. The astrocytes stimulated with Epo may further accelerate the maturation of oligodendrocytes. These comprehensive effects of Epo might also affect the ability of oligodendrocyte lineage cells to promote myelin repair in the normal and damaged adult central nervous system.     

Lipocortin-1 immunoreactivity in central and peripheral nervous system glial tumors

We examined the cellular distribution of lipocortin-1 (L-1), a major physiologic substrate for the epidermal growth factor receptor/kinase, in 122 central nervous system (CNS) and peripheral nervous system (PNS) neoplasms using the peroxidase-antiperoxidase technique with a polyclonal antibody specific for L-1. Extensive L-1 immunoreactivity was demonstrated in many CNS tumors; in 11 of 21 glioblastoma multiformes, in five of 12 anaplastic astrocytomas, and in five of 14 astrocytomas. Significant numbers of immunoreactive ependymocytes or astrocytes were also seen in six of 13 ependymomas. In contrast, no immunostaining was detected in the oligodendrocytes in any of ten oligodendrogliomas. PNS tumors, found in two of five malignant nerve sheath tumors, 13 of 15 schwannomas, 13 of 17 neurofibromas, and 14 of 15 traumatic neuromas, also contained considerable L-1 immunoreactivity in Schwann cells or mast cells. These findings raise the possibility that L-1 may participate in the proliferation or subsequent differentiation of neoplastic astrocytes, ependymocytes, and Schwann cells.     

Mapping of the distribution of polysialylated neural cell adhesion molecule throughout the central nervous system of the adult rat: an immunohistochemical study.

In the nervous system, the neural cell adhesion molecule changes at the cell surface during development, from a form highly enriched in polysialic residues to several isoforms containing much less sialic acid, and is thought to participate in the structuring of neuronal groups and in the establishment of neuronal connections. Recent observations have indicated, however, that it may not be restricted to developing tissues since it is still present in certain adult neuronal centres which can undergo morphological reorganization. In this study, therefore, we examined systematically the distribution of polysialylated neural cell adhesion molecule immunoreactivity throughout the central nervous system of adult male and female rats, using light microscopic immunocytochemistry and immunoblot analysis with an antibody that specifically recognizes the polysialic residues of the molecule. Concomitantly, we compared this immunoreactivity to that due to all isoforms of the neural cell adhesion molecule, detected with a polyclonal serum raised against the NH2-terminal of the protein. Immunoreactivity due to the polysialylated isoform was consistently visualized in several discrete areas of the adult brain and spinal cord. An intercellular punctate immunolabelling characterized the staining in certain hypothalamic and thalamic nuclei, superficial laminae of the dorsal horn of the spinal cord, ventral portion of the dentate gyrus of the hippocampus, lateral geniculate, parabrachial and habenular nuclei, bed nucleus of the stria terminalis, mesencephalic central gray and olfactory bulb. In other areas, such as the piriform cortex, dorsal aspect of the dentate gyrus and fimbria and lamina X of the spinal cord, isolated neuronal-like cells were either completely filled with immunolabel or showed a surface reaction on their cell bodies and processes. Highly immunoreactive isolated glial-like cells were also noted within the ependymal layer of the central canal and lateral ventricles and at times in the peripheral white matter of the spinal cord. In contrast to this discrete localization, staining due to all isoforms of the neural cell adhesion molecule was widespread and diffuse throughout the brain and spinal cord. The expression of the polysialylated isoform in the supraoptic nucleus and hippocampus was confirmed by immunoblot analysis; it occurred together with weakly sialylated isoforms. No obvious differences were detected in the amount or distribution of immunoreactivity due to the polysialylated isoform in relation to the sex or age of the animals (between three and 12 months of age). Our study thus demonstrates that well-defined areas of the central nervous system of the adult rat continue to express the polysialylated isoform of the neural cell adhesion molecule.(ABSTRACT TRUNCATED AT 400 WORDS)     

Insect glial cells show differential expression of a glycolipid-derived, glucuronic acid-containing epitope throughout neurogenesis: detection during postembryogenesis and regeneration in the central nervous system of Tenebrio molitor L.

The monoclonal antibody CAF-1 recognises a glucuronic acid-containing epitope present on insect acidic glycolipids. Immunohistochemical analysis of the CAF-1 epitope has revealed its differential, temporal and spatial expression during postembryogenesis of the midbrain of Tenebrio molitor. Electron microscopic resolution demonstrated, that the CAF-1 epitope is expressed on glial cells that ensheath the glomeruli of the central body. Concomitantly, a differential pattern of expression was observed in the ventral nerve cord, exhibiting a serially homologous display on glial cells that ensheath neuronal somata in the cell body layer of the thoracic ganglia and ventral associative neuropil. Prominent, topologically restricted CAF-1 immunoreactivity was monitored in termination areas of sensory neurons in the ventral associative neuropil and corresponding nerves 6-48 h after extirpation of the respective sensory neuron somata. CAF-1 expression is correlated with structural reorganisation in postembryonic nervous tissue of T. molitor.     

Interleukin-8 receptor B immunoreactivity in brain and neuritic plaques of Alzheimer's disease.

Cytokines mediate inflammatory responses through their receptors in the hematopoietic system. In a search for potential mediators of inflammatory responses in Alzheimer's disease, we examined brain for cytokine receptors. Herein we describe interleukin-8 receptor B (IL-8RB, also termed CXCR2) immunoreactivity in the central nervous system. Strong IL-8RB immunoreactivity is present in both Alzheimer's disease and control brains. Neurons, dendrites, and axons are clearly immunoreactive. In Alzheimer's disease, IL-8RB immunoreactivity is also present in some swollen dystrophic neurites of neuritic plaques. Double staining and confocal microscopic analysis reveals that these IL-8RB-positive neurites in plaques are neurofilament positive and are distinct from astrocytic or microglial processes. In general, these IL-8RB-positive neurities do not co-localize with PHF-1 or AT8 (hyperphosphorylated tau) immunoreactive neurites but instead co-localize with beta PP-positive neurites. These results demonstrate for the first time IL-8RB immunoreactivity in the central nervous system and imply a new role for this receptor outside the hematopoietic system. The strong presence of IL-8RB on neurons and the potential of glial cells to produce IL-8 suggest that this system might mediate neuronal-glial interactions.     

Orexin-A immunoreactive cells and fibers in the central nervous system of the axolotl brain and their association with tyrosine hydroxylase and serotonin immunoreactive somata

Orexin-A-like immunoreactivity in the axolotl brain was investigated by immunohistochemistry. Immunoreactive somata formed a single group in the hypothalamus, but were distributed beyond several nuclei, namely, the ventral aspect of the nucleus preopticus posterior, dorsal aspect of the nucleus suprachiasmaticus and anterior aspect of the pars ventralis hypothalami. Immunoreactive fibers were distributed throughout the brain from the olfactory bulb to the spinal cord except the cerebellum. The densest immunoreactive fibers were seen in the medial forebrain bundle and caudal lateral forebrain bundle. The largest number of immunoreactive puncta were seen in the mesencephalic tectum in addition to the hypothalamus. Immunoelectron microscopic analysis revealed the presence of synaptoid connections of immunoreactive fibers on neuronal somata in the tectum. The function of the mesencephalic system in the urodele seems to be sensory integration, suggesting that the orexin-A nervous system is associated with the modulation of sensory inputs. Orexin-A immunoreactive puncta were also observed on catecholaminergic and serotonergic somata. In view of the restricted somatic distribution in the hypothalamus, wide distribution of fibers throughout the central nervous system (CNS), and intimate association with monoaminergic somata, the orexin nervous system in the axolotl CNS is similar to those of other vertebrates, suggesting that this system is essential for brain functions throughout vertebrates.     

Cell-specific localization of monocarboxylate transporters, MCT1 and MCT2, in the adult mouse brain revealed by double immunohistochemical labeling and confocal microscopy

Recent evidence suggests that lactate could be a preferential energy substrate transferred from astrocytes to neurons. This would imply the presence of specific transporters for lactate on both cell types. We have investigated the immunohistochemical localization of two monocarboxylate transporters, MCT1 and MCT2, in the adult mouse brain. Using specific antibodies raised against MCT1 and MCT2, we found strong immunoreactivity for each transporter in glia limitans, ependymocytes and several microvessel-like elements. In addition, small processes distributed throughout the cerebral parenchyma were immunolabeled for monocarboxylate transporters. Double immunofluorescent labeling and confocal microscopy examination of these small processes revealed no co-localization between glial fibrillary acidic protein and monocarboxylate transporters, although many glial fibrillary acidic protein-positive processes were often in close apposition to elements labeled for monocarboxylate transporters. In contrast, several elements expressing the S100beta protein, another astrocytic marker found to be located in distinct parts of the same cell when compared with glial fibrillary acidic protein, were also strongly immunoreactive for MCT1, suggesting expression of this transporter by astrocytes. In contrast, MCT2 was expressed in a small subset of microtubule-associated protein-2-positive elements, indicating a neuronal localization.In conclusion, these observations are consistent with the possibility that lactate, produced and released by astrocytes (via MCT1), could be taken up (via MCT2) and used by neurons as an energy substrate.     

Monoclonal antibody BM89 recognizes a novel cell surface glycoprotein of the L2/HNK-1 family in the developing mammalian nervous system.

A monoclonal antibody, BM89, obtained with Triton X-114-treated pig synaptic membranes as an immunogen, recognizes a neuronal antigen in the newborn porcine nervous system. By immunohistochemistry, BM89 staining was observed within the neuropil of all areas of the forebrain and spinal cord tested. In addition, BM89 labeled the cell bodies and proximal dendrites of spinal cord neurons. In the peripheral nervous system, BM89 immunoreactivity was present in a subpopulation of dorsal root ganglion neurons and was predominantly associated with non-myelinated axons in peripheral nerves. Initial biochemical characterization of the antigen in pig brain showed that it is an integral membrane glycoprotein with a molecular weight of 41,000. Moreover, it cross-reacts with the L2/HNK-1 carbohydrate epitope expressed by members of a large family of glycoproteins. Homologous antigens with molecular weights of 41,000-43,000 were identified in the rat, rabbit and fetal human brain. Immunoblotting and immunohistochemistry revealed that the epitope recognized by BM89 is developmentally regulated in the rat nervous system. In cryostat sections from rat cerebellum, spinal cord and dorsal root ganglia, an age-dependent decline of BM89 immunoreactivity was observed during postnatal development. In the cerebellum, the BM89 epitope was very abundant in cells of the external and the internal granular layers between postnatal days 5 and 15. During this period some staining was also identified in the developing molecular layer and the prospective white matter. Subsequently, and in the adult, overall staining was greatly reduced and remaining immunoreactivity was associated only with the internal granular layer. In the spinal cord and dorsal root ganglia, staining was very prominent at postnatal day 5; it decreased considerably thereafter and was barely detectable in the adult. Immunostaining of rat brain and dorsal root ganglion cultures revealed that the BM89 antigen is a cell surface molecule expressed by a subpopulation of central and peripheral nervous system neurons. The biochemical properties in conjunction with the topographical location and the developmental profile of the antigen recognized by BM89 suggest that it may represent a developmentally important recognition molecule.     

Immunohistochemical localization of glial cell line-derived neurotrophic factor in the human central nervous system

Glial cell line-derived neurotrophic factor, initially purified from the rat glial cell line B49, has the ability to promote the survival and differentiation of various types of neurons in the central and peripheral nervous systems. In the present study, to evaluate the physiological role of glial cell line-derived neurotrophic factor in the central nervous system, we investigated the cellular and regional distribution of glial cell line-derived neurotrophic factor immunoreactivity in autopsied control human brains and spinal cords using a polyclonal glial cell line-derived neurotrophic factor-specific antibody. On western blot analysis, the antibody reacted with recombinant human glial cell line-derived neurotrophic factor, and recognized a single band at a molecular weight of approximately 34,000 in human brain homogenates. Glial cell line-derived neurotrophic factor immunoreactivity was observed mainly in the neuronal somata, dendrites and axons. In the telencephalon, diencephalon and brainstem, the cell bodies and proximal processes of several neuronal subtypes were immunostained with punctate dots. Furthermore, immunopositive nerve fibers were also observed, and numerous axons were intensely immunolabeled in the internal segment of the globus pallidus and the pars reticulata of the substantia nigra. In the cerebellum, the most conspicuous immunostaining was found in the Purkinje cells, in which the somata and dendrites were strongly immunolabeled. Intense immunoreactivity was also detected in the posterior horn of the spinal cord. In addition to the neuronal elements, immunopositive glial cell bodies and processes were observed in various regions.

Our results suggest that glial cell line-derived neurotrophic factor is widely localized, but can be found selectively in certain neuronal subpopulations of the human central nervous system. Glial cell line-derived neurotrophic factor may regulate the maintenance of neuronal functions under normal circumstances.     

Atrial natriuretic factor-like immunoreactivity in the central nervous system of the frog

The distribution of atrial natriuretic factor-like immunoreactivity in the central nervous system of the frog Rana ridibunda was investigated by indirect immunofluorescence and the immunogold technique, using an antiserum generated in rabbits against synthetic atrial natriuretic factor (Arg 101-Tyr 126). A stereotaxic atlas of neurons containing atrial natriuretic factor-like material was prepared to show the widespread distribution of atrial natriuretic factor-positive cell bodies and fibres in the brain. Appreciable numbers of immunoreactive perikarya were observed in the dorsal and medial pallium, the medial septal nucleus, the anteroventral and ventrolateral areas of the thalamus, the lateral forebrain bundle, the posterocentral and posterolateral thalamic nuclei, the preoptic nucleus, the dorsal infundibular nucleus and the anteroventral tegmental nucleus of the mesencephalon. A heavy accumulation of atrial natriuretic factor-like immunoreactive cell bodies and very dense fibre bundles were noted in the interpeduncular nucleus of the mesencephalon. Fibres were generally seen where cell bodies were observed, particularly in all regions of the pallium and septum nuclei, in the ventral thalamus, the infundibular nucleus and the tegmental area. Moderate numbers of fibres were also noted in several regions where cell bodies were absent, mainly in the amygdala and the infundibular nucleus, the median eminence and most mesencephalic regions. At the electron microscopic level, the immunoreactivity was restricted to dense core vesicles and absent in clear vesicles. These results provide the first evidence for the presence of atrial natriuretic factor in the brain of a non-mammalian chordate. The localization of atrial natriuretic factor-positive material in the frog central nervous system suggests that this peptide may act as a neuromodulator or a neurotransmitter in amphibians.     

Lipocortin-1 immunoreactivity in the normal human central nervous system and lesions with astrocytosis

The authors have examined the cellular distribution of lipocortin-1 (L-1) in the normal and diseased central nervous system (CNS) using the peroxidase-antiperoxidase (PAP) technique with a polyclonal antibody specific for L-1. L-1 immunoreactivity was evaluated in the frontal cortex, parahippocampal gyrus/lateral ventricle, cerebellum, medulla, and spinal cord from 27 normal human fetuses, neonates, and adults without neurologic disease and in these same regions and representative lesions from 35 patients with diseases producing varying degrees of astrocytosis, including intraparenchymal hemorrhage; embolic, thrombotic, or traumatic infarctions; and Alzheimer's disease (AD). L-1 immunoreactivity was identified in ependymocytes, choroid plexus epithelia, and scattered subependymal astrocytes throughout the ventricular system from 15 weeks gestation through 82 years of age in both normal and diseased CNSs. L-1 immunoreactivity was also detected in reactive astrocytes and many macrophages surrounding each infarction regardless of site or pathogenesis and in scattered reactive astrocytes in people with AD or SDAT. The limited distribution of L-1 in CNS is consistent with the low amounts of L-1 found in brain and suggests that L-1 may participate in the normal function of ependymocytes and the pathophysiology of reactive astrocytosis.     

Immunocytochemical localization of glycogen phosphorylase kinase in rat brain sections and in glial and neuronal primary cultures

Summary. The physiological function of brain glycogen and the role of phosphorylase kinase as a regulatory enzyme in the cascade of reactions associated with glycogenolysis in the brain have not been fully elucidated. As a first step toward elucidating such a function, we studied the localization of phosphorylase kinase in glial and neuronal primary cell cultures, and in adult rat brain slices, using a rabbit polyclonal antibody against skeletal muscle glycogen phosphorylase kinase. Immunocytochemical examination of rat astroglia-rich primary cultures revealed that a large number of cells were positive for glycogen phosphorylase kinase immunoreactivity. These cells were also positive for vimentin, a marker for immature glia, while they were negative for glial fibrillary acidic protein, a marker for mature astroglia, and for galactocerebroside, an oligodendroglial marker. Neurons in rat neuron-rich primary cultures did not show any kinase-positive staining. In paraformaldehyde-fixed adult rat brain sections, phosphorylase kinase immunoreactivity was detected in glial-like cells throughout the brain, with relatively high staining found in the cerebral cortex, the cerebellum, and the medulla oblongata. Phosphorylase kinase immunoreactivity could not be detected in neurons, with the exception of a group of large neurons in the brain stem, most likely belonging to the mesencephalic trigeminal nucleus. Phosphorylase kinase was also localized in the choroid plexus and to a lesser degree in the ependymal cells lining the ventricles. Phosphorylase kinase thus appears to have the same cellular distribution in nervous tissue as its substrates, i.e. glycogen phosphorylase and glycogen, which suggests that the physiological role of brain phosphorylase kinase is the mobilization of glycogen stores to fuel the increased metabolic demands of neurons and astrocytes.     

Nerve growth factor in the adult brain of a teleostean model for aging research: Nothobranchius furzeri

Nerve growth factor (NGF) acts on central nervous system neurons, regulating naturally occurring cell death, synaptic connectivity, fiber guidance and dendritic morphology. The dynamically regulated production of NGF beginning in development, extends throughout adult life and aging, exerting numerous roles through a surprising variety of neurons and glial cells.This study analyzes the localization of NGF in the brain of the teleost fish Nothobranchius furzeri, an emerging model for aging research due to its short lifespan. Immunochemical and immunohistochemical experiments were performed by employing an antibody mapping at the N-terminus of the mature chain human origin NGF. Western blot analysis revealed an intense and well defined band of 20 kDa, which corresponds to proNGF of N. furzeri. Immunohistochemistry revealed NGF immunoreactivity (IR) diffused throughout all regions of telencephalon, diencephalon, mesencephalon and rhomboencephalon. It was detected in neurons and in glial cells, the latter mostly lining the mesencephalic and rhomboencephalic ventricles. Particularly in neurons, NGF IR was localized in perikarya and, to a less extent, in fibers.The widespread distribution of proNGF suggests that it might modulate numerous physiological functions in the adult brain of N. furzeri. The present survey constitutes a baseline study to enhance the understanding of the mechanisms underlying the role of NGF during aging processes.     

A review of functional heterogeneity among astrocytes and the CS56-specific antibody-mediated detection of a subpopulation of astrocytes in adult brains

Astrocytes comprise the largest class of glial cells in the mammalian central nerve system (CNS). Although astrocytes were long considered to be a homogeneous population of neuron-supporting cells, recent decades have seen a shift toward the recognition that astrocytes exhibit morphological and functional heterogeneities and serve as essential modulators of brain functions. However, the mechanism underlying astrocyte diversity remains unclear, and the different subpopulations are difficult to identify due to a lack of specific cell markers. In this review, I discuss current knowledge regarding astrocyte heterogeneity and introduce a subpopulation that can be detected via labeling with a chondroitin sulfate-specific antibody (CS56). These CS56-positive astrocytes were found to selectively express tenascin-R (TNR) in the adult mouse cerebral cortex. Further research demonstrated significantly lower levels of glutamate uptake activity and glutamate aspartate transporter expression in TNR-knockdown astrocytes relative to controls, suggesting that the expression and secretion of Tnr by a subpopulation of astrocytes may contribute to region-specific neuron–astrocyte interactions. In summary, these results suggest that CS56-specific antibody and Tnr could be used as novel markers to detect an astrocyte subpopulation in the adult CNS.