Immunocytochemical localization and developmental profile of neuron specific enolase (NSE) and non-neuronal enolase (NNE) in aggregating cell cultures of fetal rat brain

cAMP/PKA signaling pathway contributes to neuronal apoptosis via regulating IDE expression in a mixed model of type 2 diabetes and Alzheimer's disease

Type 2 diabetes (T2D) may play a relevant role in the development of Alzheimer's disease (AD), however, the underlying mechanism was not clear yet. We developed an animal model presenting both AD and T2D, morris water maze (MWM) test and recognition task were performed to trace the cognitive function. Fasting plasma glucose (FPG) and oral glucose tolerance test (OGTT) were determined to trace the metabolism evolution. TUNEL assay and apoptosis-related protein levels were analyzed for the detection of neuronal apoptosis. Cyclic adenosine monophosphate (cAMP) agonist bucladesine or protein kinase (PKA) inhibitor H-89 were used to determine the effects of cAMP/PKA signaling pathway on IDE expression and neuronal apoptosis. The results showed that T2D contributes to the AD progress by accelerating and worsening spatial memory and recognition dysfunctions. Metabolic parameters and glucose tolerance were significantly changed in the presence of the AD and T2D. The significantly induced neuronal apoptosis and increased pro-apoptotic proteins in mice with AD and T2D were also observed. We showed the decreased expression level of IDE and the activating of cAMP/PKA signaling pathway in AD and T2D mice. Further studies indicated that cAMP agonist decreased the expression level of IDE and induced the neuronal apoptosis in mice with AD and T2D; whereas PKA inhibitor H-89 treatment showed the completely opposite results. Our study indicated that, in the T2D and AD mice, cAMP/PKA signaling pathway and IDE may participate in the contribute role of T2D in accelerating the pathological process of AD via causing the accumulation of Aβ and neuronal apoptosis.

Quantitative proteomics analysis of specific protein expression and oxidative modification in aged senescence-accelerated-prone 8 mice brain

The senescence-accelerated mouse (SAM) is a murine model of accelerated senescence that was established using phenotypic selection. The SAMP series includes nine substrains, each of which exhibits characteristic disorders. SAMP8 is known to exhibit age-dependent learning and memory deficits. In our previous study, we reported that brains from 12-month-old SAMP8 have greater protein oxidation, as well as lipid peroxidation, compared with brains from 4-month-old SAMP8 mice. In order to investigate the relation between age-associated oxidative stress on specific protein oxidation and age-related learning and memory deficits in SAMP8, we used proteomics to identify proteins that are expressed differently and/or modified oxidatively in aged SAMP8 brains. We report here that in 12 month SAMP8 mice brains the expressions of neurofilament triplet L protein, lactate dehydrogenase 2 (LDH-2), heat shock protein 86, and alpha-spectrin are significantly decreased, while the expression of triosephosphate isomerase (TPI) is increased compared with 4-month-old SAMP8 brains. We also report that the specific protein carbonyl levels of LDH-2, dihydropyrimidinase-like protein 2, alpha-spectrin and creatine kinase, are significantly increased in the brain of 12-month-old SAMP8 mice when compared with the 4-month-old SAMP8 brain. These findings are discussed in reference to the effect of specific protein oxidation and changes of expression on potential mechanisms of abnormal alterations in metabolism and neurochemicals, as well as to the learning and memory deficits in aged SAMP8 mice.

Human rotation-mediated fetal mixed brain cell aggregate culture: characterization and N-methyl-D-aspartate toxicity

One difficulty in generating in vitro models of neuropathogenesis lies in maintaining stable proportions of primary neurons within a mixed brain cell population. Rotation-mediated fetal brain aggregate culture has been modified to permit growth of human primary fetal brain cells containing 50 to 60% neurons. After 12 weeks cholinesterase, neuron specific enolase and microtubule-associated protein-2 were demonstrable by biochemical assay and immunocytochemical labelling of cryostat sections of human fetal brain aggregates. Upon exposure to the glutamate agonist; N-methyl-D-aspartate for 7 days at 35 days in vitro neuron specific enolase and cholinesterase decreased to 60 to 70% of untreated levels. Glial fibrillary acidic protein did not change significantly but swollen astrocytes were seen in labelled sections of treated aggregates. This method is useful to study human neurotoxicity and degeneration in mixed glial culture without astrocyte overgrowth.

Restriction of peroxidase-mediated antibody reactivity to single neurons by local hydrogen peroxide production

Current electrophysiological and imaging methods have begun to target the subcellular structure and function of single CNS neurons. Although physiological imaging methods now permit the resolution of activity of single presynaptic and postsynaptic elements, it has not been possible to unequivocally examine the array of proteins expressed at these same structures. This problem arises from the inability of current immunocytochemical techniques to differentiate between a process of the neuron of interest and the surrounding neuropil belonging to other cells. Thus, we have sought to develop an antibody staining method which would restrict reactivity to only a single neuron. Our assay involves preloading a single neuron with the coupling reagent biocytin. Following fixation, the injected biocytin is then complexed with avidin-linked glucose oxidase, providing a means of locally generating hydrogen peroxide within a cell of interest which catalyses the peroxidase-mediated (coupled to primary antibody) staining reaction. We have used this method successfully with antibodies to a number of neuronal markers (neuron-specific enolase, neurofilament, microtubule-associated protein and the glutamate receptor GluR2/3). Our staining method enables subcellular resolution of immunocytochemical markers within a single neuron without confounding staining of neighboring cells. We anticipate that this approach will facilitate the study of neuronal phenotype in fine dendritic processes in electrophysiologically characterized neurons in specimens with a complex neuropil, such as brain slices or high-density cultures.

A comparative study of the distribution of alpha- and gamma-enolase subunits in cultured rat neural cells and fibroblasts

We report the presence and distribution of alpha (ubiquitous) and gamma (neuron-specific) subunits of the dimeric glycolytic enzyme enolase (2-phospho-D-glycerate hydrolase) in cultured neural cells. The gamma gamma enolase is found in vivo at high levels only in neurons and neuroendocrine cells. Neuronal cells in culture also contain relatively high levels of alpha gamma and gamma gamma enolase. Here we show, by enzymatic and immunological techniques, that the gamma subunit also is expressed in cultured rat astrocytes and meningeal fibroblasts and, as we previously reported, in oligodendrocytes. Both neuron-specific isoforms alpha gamma and gamma gamma are expressed in all these cells, but the alpha alpha isoform accounts for the major part of total enolase activity. The sum of alpha gamma and gamma gamma enolase activities increases with time in culture. i.e. maturation processes, reaching the highest level in oligodendrocytes (40% of total enolase activity) and 15 and 10% of total enzymatic activity in astrocytes and fibroblasts, respectively. The gamma enolase transcripts were found not only in cultured neuronal cells but also in cultured oligodendrocytes astrocytes, and meningeal fibroblasts. Our data indicate that neuron-specific enolase should be used with caution as a specific marker for neuronal cell differentiation.

Expression of neuron-specific enolase in the pineal organ of the domestic fowl during post-hatching development

Immunohistochemistry for neuron-specific enolase (NSE) revealed that NSE is localized in both a limited number of pinealocytes and intrinsic afferent neurons in the pineal organ of the domestic fowl. Furthermore, a computer-assisted three-dimensional imaging technique allowed to clarify the reverse distributional pattern of both elements: NSE-positive pinealocytes displayed a dense distribution especially in the vesicular portion of the gland, whereas NSE-immunoreactive nerve cells were mainly found in the pineal stalk. The number of NSE-positive intrinsic neurons in the pineal organ of chickens decreased rapidly after hatching, with a concentration of these elements in the basal portion (stalk) of the pineal organ. On the other hand, immunoreactive pinealocytes increased remarkably in the end-vesicle of the organ with age, followed by a gradual expansion toward the proximal portion. Thus, the spectacular increase in NSE-positive pinealocytes and the progressive reduction of reactive neurons occurred in parallel during the course of post-hatching development. NSE-immunoreactive pinealocytes displayed morphological characteristics of bipolar elements, endowed with an apical protrusion into the pineal lumen and a short basal process at younger stages, whereas multipolar types of NSE-positive pinealocytes were predominantly found in the adult domestic fowl. These results indicate that in the pineal organ of the domestic fowl (1) the ontogenetic expansion of NSE-immunoreactive pinealocytes is paralleled by a regressive afferent innervation, (2) the NSE-positive pinealocytes transform from a bipolar (columnar) type to a multipolar type during post-hatching development, and (3) these ontogenetic changes in the NSE-immunoreactivity and morphology of pinealocytes may reflect the development of a neurosecretory-like capacity of the organ.

Expression of neuron-specific enolase in the developing rat retina as revealed by immunocytochemistry

Expression of neuron-specific enolase (NSE) in retinal neurons was immunocytochemically investigated during the development of the rat retina. At embryonic day 14 (E14), the first immunoreaction of NSE was identified in the pigment epithelium. NSE-positive ganglion cells occurred at the inner surface of the retina by E15. Horizontal cells and photoreceptor cells became stainable for NSE in the outer portion of the neuroblastic layer as early as E17. At E20, when the majority of ganglion cells were intensely positive for NSE, immunoreactive amacrine cells first appeared at the outer surface of the developing inner plexiform layer. It was not until postnatal day 7 (P7) that NSE-positive bipolar cells occurred in the middle of the inner nuclear layer. At this stage, most of the photoreceptor cells located in the outer nuclear layer were immunolabeled, whereas the ectopic photoreceptor cells in the inner nuclear layer were devoid of immunoreaction. Most identifiable retinal neurons became strongly immunostained for NSE by P14. Our results indicate that the NSE expression of retinal neurons occurs just after their migration to the final location and prior to establishing the synaptic structures. In this paper, the characteristic sequence in which different types of retinal neurons exhibit NSE immunoreaction is discussed in the light of certain autoradiographic data on the sequence of retinal cell genesis.

Analysis of the heterogeneity within bovine pineal gland by immunohistochemistry and in situ hybridization

In the present study, we demonstrate a cortical and medullary arrangement of parenchymal cells in the bovine pineal gland by using antibodies for neuron-specific enolase, synaptophysin, and hydroxyindole O-methyltransferase (HIOMT) as markers of pinealocytes, and glial fibrillary acidic protein (GFAP) as a marker of interstitial (glial) cells. Furthermore, by means of probes specific for HIOMT mRNA, we have examined possible differences in melatonin synthesis between the cortex and the medulla. Immunoreactive pinealocytes for each antigen investigated are more densely distributed in the cortex than in the medulla. In the cortex, GFAP-positive interstitial cells have large intenselystained somata endowed with several long, thin cytoplasmic processes, whereas in the medulla, they display smaller, less intensely labeled perikarya from which numerous fine short processes emerge. Golgi staining has confirmed these morphological differences between the interstitial cells in the cortex and those in the medulla. An analysis using confocal laser microscopy together with in situ hybridization for HIOMT mRNA has shown that the expression of mRNA transcripts in the cortex is more intense than that in the medulla. The expression of the HIOMT gene in a cluster of cells in the medial habenular nucleus is lower than that in pinealocytes of the pineal organ proper.

Morphological differentiation of neuropeptide Y neurons in aggregate cultures of dissociated fetal cortical cells: a model system for glia-neuron paracrine interactions

The temporal changes in the morphological profiles of neuropeptide Y (NPY) neurons and their topographical relationship with glial cells (astrocytes) were characterized in aggregate cultures derived from fetal cortical tissue using immunocytochemical procedures. On day 6 of culture, structures labelled with NPY antibodies were small and uneven in size but many resembled neuronal cell bodies. On day 14, neuronal perikarya were well defined and several morphological types of NPY neurons could be distinguished most of which gave rise to beaded processes: unipolar or multipolar bitufted neurons whose processes branch in close proximity to the cell body; bipolar neurons; and multipolar neurons. On day 23, heavily punctate and asymmetrically labelled cell bodies were dispersed throughout the aggregate; neuronal processes were less conspicuous. At 14 and 23 days, cells expressing glial fibrillary acidic protein (GFAP) and neuronal specific enolase (NSE) were abundantly distributed throughout the aggregate. Using a double immunoreaction on 14-day-old aggregates revealed that GFAP+ cells and their processes were in close apposition to and engulfing the NPY neurons. Thus, dissociated fetal NPY neurons undergo morphological differentiation in culture along with astrocytes (GFAP+) and other neuronal cell types (NSE+). Based on the topographical association of astrocytes and neurons, particularly NPY neurons, we propose that the aggregate culture system can serve as a model to study the role of paracrine interactions in the regulation of the expression of NPY.

Measurement of gamma-enolase release, a new method for selective quantification of neurotoxicity independently from glial lysis

We have developed a sensitive enzymatic-immunoassay to quantify the level of gamma-enolase (a specific neuronal enzyme) which is released from cultured cells after exposure to various toxins. We show that this method can estimate selectively neuronal cell death without significantly interfering with glial cell death. Indeed, no gamma-enolase is released when glial cells are killed with free-radical producing agents. Experiments comparing the levels of neuronal cell death induced by NMDA or free-radical producing drugs, performed either by measuring gamma-enolase release or using the classical fluorescein diacetate method, yielded similar results. In addition to selectively follow neuronal death in a mixed population of neurons and glial cells, this method provides a way of determining the cell death kinetics from a single culture dish, since enolase can be measured on small samples taken from the culture medium. Finally, we propose these two methods as being complementary and useful neuronal and other cellular death indexes and also to understand the complex problem of glial influence on neuronal survival or death.

Effect of chronic pre- and post-natal low-dose ethanol exposure on brain enolase isoenzyme activities

Sprague-Dawley dams were treated with 3 v/v % ethanol in liquid diet from the 8th day gestation through 3 weeks nursing period. Offsprings, ages 1, 2 and 3 weeks, and their dams were studied. Brain weights and their total proteins were not affected by this ethanol treatment. Total enolase activity/mg protein and its isoenzymes, i.e. non-neuron-specific, hybrid and neuron-specific, (mumol/min/mg protein) in 100,000 g supernate, were significantly lower in the treated. Additionally, enolase isoenzyme transformation was delayed.

Insulin-like growth factor I stimulates oligodendrocyte development and myelination in rat brain aggregate cultures

Insulin-like growth factor I (IGF-I) and high concentrations of insulin have been shown to stimulate an increase in the number of oligodendrocytes that appear in developing monolayer cultures of rat brain cells (McMorris et al., Proc Natl Acad Sci USA 83: 822-826, 1986; McMorris et al., Ann NY Acad Sci 605:101-109, 1990; McMorris and Dubois-Dalcq, J Neurosci Res 21:199-209, 1988). In the present study, we investigated whether IGF-I or insulin treatment induces a corresponding increase in the synthesis and accumulation of myelin. Aggregate cultures, established from 16-day-old fetal rat brains, were treated with either 100 ng/ml IGF-I or 5,000 ng/ml insulin and analyzed for the number of oligodendrocytes, activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP), total amount of myelin, and synthesis rate of myelin proteins. Cultures treated with IGF-I beginning on day 2 after explantation contained 35-80% more oligodendrocytes and had 60-160% higher CNP activity than controls when tested on day 13, 20, or 27. By day 27, treated cultures had 35-90% more myelin than controls. Similar results were observed in response to 5,000 ng/ml insulin, a concentration at which insulin binds to IGF receptors and acts as an analogue of IGF-I. The synthesis rate of myelin proteins was measured in experiments using 5,000 ng/ml insulin. When treatment was begun at day 20 rather than day 2, cultures did not exhibit an increased number of oligodendrocytes over control during the following 4-6 days.(ABSTRACT TRUNCATED AT 250 WORDS)

A normal human brain cell aggregate model for neurobiological studies

A new in vitro model of normal human brain has been developed in which fetal human brain cells form three-dimensional aggregates that can be maintained for up to 60 days in culture. Cells appear fully differentiated at the time of initiation in culture; the predominant cells identified were astrocytes, neurons, and oligodendrocytes with myelin, with occasional ependymal cells and macrophages. The specific arrangement and numbers of neural cells within aggregates differed among brain specimens. Cell kinetics studies detected DNA synthesis throughout the culture interval. Aggregates cocultured with a human malignant glioma cell line (U251-MG) were progressively invaded by tumor cells. In aggregates infected with human cytomegalovirus (CMV), intracellular viral replication and morphologic changes characteristic of human brain infection with this pathogen were seen. This model of brain aggregates should prove valuable for multidisciplinary studies in human neurobiology, particularly in the fields of developmental neurobiology, neuro-oncogenesis, tumor cell invasion, and species-specific viral infection of the central nervous system.

A hypothesis for myeloschisis: overgrowth and reopening. An experimental study

A hypothesis for embryopathogenesis of myeloschisis is described on the basis of experimental studies analyzing the stage specificity and immunohistochemical/histological characteristics of the exposed neural tissue (placode). Myeloschisis developed in six fetuses among 205 chick embryos treated in various stages with teratogens including ethylnitrosourea, and anticonvulsant and antipyretic agents. All but one case (with associated cephalothoracopagus) demonstrated myeloschisis in the thoracic region with a lamina defect of two and three levels. No fetus was exposed to a teratogen prior to or within Hamburger and Hamilton stage 12 (45 to 49 hours postincubation), when the neuropore closes. Immunohistochemical studies of chick myeloschisis clearly indicated that neuron-specific enolase-positive elements were extremely active only in the overgrown placode, corresponding to the histological findings with Kluver-Barrera's special stain. These findings were compared with observations in a case of myeloschisis in a human neonate. The results of this study imply the possibility of another mechanism for the embryopathogenesis of myeloschisis: namely, the overgrowth and reopening hypothesis.

Immunohistochemical study of the early human fetal brain

To assess the cytogenesis of the central nervous system we studied the spinal cord and the cerebrum in 11 human embryos and fetuses of gestation age 7-25 weeks immunohistochemically using anti-vimentin, anti-neurofilament protein (NFP), anti-neuron-specific enolase (NSE), anti-glial fibrillary acidic protein (GFAP), anti-S-100 protein, anti-Leu 7 and anti-myelin basic protein (MBP) antibodies. Vimentin was demonstrated in ventricular cells at 7 weeks and older. NFP-68-kDa and -160-kDa components were observed in neuroblastic cells of the neural tube at 7 weeks. NFP (68 and 160 kDa) was mainly located in the marginal zone of the spinal cord and the cerebrum at 8-9 weeks. NSE was not found in the neural tube at 7 weeks, although NSE was demonstrable at 9 weeks both in the spinal cord and in the cerebrum. GFAP-positive cells started to appear at 9 weeks in the spinal cord and at 15 weeks in the cerebrum, respectively. S-100 immunoreactivity was almost coincident with GFAP. S-100, however, was observed in more numerous glioblastic cells. Leu 7 was detected at 7 weeks and located in the neuropil of the central nervous tissue. MBP was not demonstrable in this study. Our study indicates that neuronal differentiation occurs much earlier than glial differentiation in the human brain and that neuronal and glial cell classes do not coexist in the ventricular zone of the early human fetal brain.

Neuron-specific enolase during the development of the organ of Corti

NSE immunoreactivity has been studied in the organ of Corti of the developing mouse from birth to 21 days. NSE immunohistochemical stain is observed in spiral ganglion cells, in nerve fibers and in nerve endings of inner and outer hair cells, and in both populations of sensory cells. Spiral ganglion cells in lower and central parts of the ganglion stain for NSE at birth, but all nerve cells are stained by day 4. Radial and spiral fibers and the endings on inner hair cells stain at birth, but the nerve endings on outer hair cells develop NSE between days 3 and 6. The inner and outer hair cells are NSE-positive at day 2 but the NSE immunoreactivity in the outer hair cells decreases at the end of the second week until the cells become negative. The NSE stain in the neuronal pathways of the inner and outer hair cell regions increases for about 19 days, showing a predominant accumulation in neuronal endings. The data suggest that the development of NSE expression in the organ of Corti reflects the nascence and maturation of the synaptic contacts. Spiral neurons, their fibers and endings as well as inner and outer hair cells express NSE in the isolated organ of Corti in culture. Variability of stain among the different cell populations indicates a role of local factors in the regulation of NSE expression.

Nutrition and fetal brain maturation. I. Responses in vitro and in vivo

The glycolytic enzyme enolase increases during the perinatal period of brain development and was utilized as a marker for examining the effect of culture environment on differentiation of cells from 20-day fetal rat brain. Enolase activity in cell cultures increased from 0.91 +/- 0.03 (Day 0) to 2.11 +/- 0.10 mumol/min/mg protein (Day 6). Comparable levels were not reached in vivo until neonatal pups were 15 days old. The in vitro increase was inhibited by both cycloheximide and actinomycin D. Enolase activity in the cells responded to alterations in both incubation media and homologous serum. After 6 days in culture, cells incubated in rat serum (10%) added to MEM or RPMI produced twice as much enolase activity as cells incubated similarly in Ham's medium, i.e., 1.96 +/- 0.09 and 1.85 +/- 0.21 vs 1.02 +/- 0.09, P less than 0.001. Results of a comparable magnitude were obtained when fetal calf serum replaced adult rat serum, but enolase production was somewhat lower when newborn calf serum replaced adult rat or fetal calf serum. When cells were incubated for 6 days with graded concentrations of adult rat serum (2.5-15%), enolase activity increased progressively. The pattern of enolase response suggests that the fetal rat brain cell model described herein will provide a sensitive probe with which to gain insight into nutrition and fetal brain development.

Neurotrophic effect of naturally occurring long-chain fatty alcohols on cultured CNS neurons

A long-chain fatty alcohol,n-hexacosanol, that we have isolated from the Far-Eastern traditional medicinal plant, Hygrophila erecta, Hochr., is shown to promote the maturation of central neurons. Added at 500 nM to fetal rat brain neurons in culture, it increased both neurite outgrowth by a factor of 4-6 and the number of collaterals, especially in multipolar neurons. The biochemical differentiation of cultured neurons was also strikingly enhanced by this compound: it increased the protein content and almost doubled the activities of two neuron-specific enzymes, phosphate-activated glutaminase and neuron-specific enolase, by 92 and 78%, respectively. Extensive studies with several synthetic long-chain fatty alcohols showed that the neurotrophic activity was maximal for n-hexacosanol. It is suggested that some long-chain fatty alcohols with an appropriate length of hydrocarbon chain might play an important role in central neuron development.

Electron-immunocytochemical localization of neuron-specific enolase in cytoplasm and on membranes of primary and metastatic cerebral tumours and on glial filaments of glioma cells

A series of primary and metastatic human brain tumours was evaluated immunocytochemically for the electron microscopic localization of neuron-specific enolase (NSE). All contained cells which, regardless of the cell type, demonstrated an irregular distribution of NSE in their cytoplasm and on membranes. This was in contrast to the staining pattern in normal central nervous system (CNS) cells which, as previously reported (Vinores et al. 1984b), show only diffuse cytoplasmic staining usually not associated with membranes. In the tumours, the interior of nuclei and the cristae and matrices of mitochondria were consistently negative, as in normal CNS cells. Except in one low-grade fibrillary astrocytoma, the cytoplasmic filaments in neoplastic astrocytes were often, but not invariably, stained for NSE. The fine structural localization of NSE in neoplastic cells suggests that the conversion of 2-D-glycerophosphate to phosphoenolpyruvate by enolase may occur on the membrane and, in the case of astrocytic tumours, on the cytoplasmic filaments as well as in the cytoplasm. When cells which contain only the non-neuronal form of enolase (NNE) transform to neoplastic cells, they may acquire the ability to produce NSE. This presumably enables them to accommodate the increased metabolic demands of neoplasia by allowing them to elude the regulatory controls that are specific for NNE.

Demonstration of differential immunohistochemical localization of the neuron-specific enolase antigen in rat pinealocytes

A refined method for the immunohistological demonstration of neuron-specific enolase (NSE) on 1- to 2-micron Epon-812 section gave characteristic staining of cerebral and cerebellar neurons. This method has made it possible to obtain a more detailed characterization of the heterogeneity of rat pinealocytes in the superficial portion of the rat pineal complex. Thirty adult male rats have been studied, five of which were used in a photometric analysis of the distribution of NSE. Pinealocytes stained either intensely or weakly for the NSE antigen and exhibited an uneven distribution within a given region. Further analysis of the gland revealed a distal to proximal decrease in stain intensity. It is suggested that the more strongly stained cells, being concentrated distally, are under sympathetic control.

Normal and malignant neural cells: a comprehensive survey of human and murine nervous system markers

Tumor-associated neural markers are finding increased application in diagnostic histopathology and in the development of brain tumor therapy. The major cell-type-specific markers and monoclonal antibodies that identify murine and human neural cells are reviewed in this study. Monoclonal antibodies, raised against fetal and adult neural tissue, neuroectodermal tumor tissue, or cell line immunogens which recognize epitopes on brain tumors are comprehensively described including antigens common to the nervous, hematopoietic, and immune systems. The clinical application of neural cell markers and monoclonal antibodies for the diagnosis, localization, and treatment of neuroectodermal tumors is reviewed.

Development of neuronal markers in aggregating fetal rat telencephalon cells cultured in the presence of triiodothyronine

The concentrations of the general neuronal markers D2-protein (N-CAM), D3-protein and neuron specific enolase (NSE) in reaggregating cultures of fetal rat telencephalon cells were affected by the presence of 30 nM triiodothyronine in the defined culture medium. The extent of normal developmental changes were enhanced by triiodothyronine, as demonstrated by crossed immunoelectrophoresis. From 13 to 19 days in culture, the concentration of D2-protein decreased, and the concentrations of both D3-protein and NSE increased. Nerve growth factor (NGF) was without effect on the development of these general neuronal markers. However, as shown previously both triiodothyronine and NGF increased the activity of choline acetyltransferase, a marker for cholinergic neurons. The results suggest an enhanced overall differentiation of several types of telencephalon neurons in the presence of triiodothyronine, and a specific stimulation of cholinergic telencephalon neurons by NGF.

Changes in the levels of neural cell specific proteins in the developing rat brain

The levels of S-100 protein (S-100) and neuron-specific enolase (NSE) in the developing rat brain were determined by a sensitive enzyme immunoassay and the results were compared with those obtained by other methods. Changes with development in the levels of S-100, NSE, and 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), biochemical markers for astroglia, neurons and oligodendroglia respectively, were determined in various brain regions including the cerebral hemisphere (CH), brain stem (BS) and cerebellum (Ce). The peak increments of S-100, NSE, and CNPase activity were reached later than that of the brain weight in all of the regions. The ratios of S-100/NSE and CNPase/NSE rose during the 21 days after birth in the CH and BS; the S-100/NSE ratio in the CH began to decrease from the 21st day, whereas the CNPase/NSE ratio continued to rise even after the 30th day, suggesting different maturation periods of the different glial cells. In the Ce, the change of these ratios showed a pattern different from those in the other regions. In the CH of rats with experimental microencephaly induced by methylazoxymethanol (MAM), the ratios were almost normal, in spite of the reduction of the brain weight to about 50% of the control.

Enhancement by estrogen treatment of -bungarotoxin binding in fetal mouse amygdala cells reaggregated in vitro

Dissociated amygdala cells from 17-day-old mouse fetuses were cultivated in a flask for 7 days to form aggregates. In the aggregates there developed typical synaptic structures and [125I]alpha-bungarotoxin binding capacity. An addition of estradiol (100 ng/ml) in the culture medium caused a significant increase in the toxin binding capacity. From these results it is concluded that estradiol enhances alpha-bungarotoxin binding capacity in the amygdala by exerting direct effects on the developing amygdala cells.

Developmental changes of neuron-specific enolase in human brain: an immunohistochemical study

Developmental changes of neurons containing neuron-specific enolase (NSE) in human brain were studied in various areas of the central nervous system by immunohistochemistry with the peroxidase-antiperoxidase (PAP) method. In the brain stem, Purkinje cells, dentate nucleus, globus pallidus and thalamus, the number of NSE-positive neurons increased from an early period in gestation. However, in the pontine nucleus and putamen, it gradually increased along with decreasing cellularity later in gestation and in the infantile period. In the cerebral cortex, NSE-positive neurons developed as late as in the putamen and their cellularity increased earlier in the 5th layer than in the 3rd layer. Developmental changes of NSE-positive neurons parallel phylogenesis. The appearance of NSE-positive neurons can be a marker of neuronal maturation.

Parvalbumin, a neuronal protein in brain cell cultures

Dissociated brain cell cultures were derived from 14-day-old embryonic as well as from newborn mice. The cells were grown in a medium containing 10% fetal calf serum. Indirect immunofluorescence was performed using antisera directed against the Ca2+-binding protein parvalbumin (Mr 12,000). In embryonic cultures a large proportion of cells was intensely stained by antiparvalbumin . In double-labelling experiments involving the simultaneous application of antisera against parvalbumin and the neuron-specific enolase, the enolase-containing cells were also parvalbumin-positive and both antisera revealed identical intracellular staining patterns. Conversely, almost no parvalbumin- and enolase-positive cells were present in cultures derived from newborn mice. However, in these cultures many cells were immunoreactive toward the myelin basic protein, an accepted marker for oligodendrocytes. The presence of parvalbumin within the embryonic brain cell cultures was confirmed by analyses of the culture extracts (4 mM EDTA, pH 7.5) by HPLC on reverse-phase supports, two-dimensional polyacrylamide gel electrophoresis, and immunoblotting. The present study suggests that in mouse brain cell cultures, parvalbumin is localized in neurons.

Expression of neuron-specific enolase in cultured neurons from the fetal rat

A specific antiserum to neuron-specific enolase (NSE), an isoenzyme of the glycolytic enzyme enolase, has been used to immunocytochemically study the differentiation of dissociated embryonic brain cells grown in serum-supplemented or serum-free (defined) medium for 4-28 days. The number of positively stained neurons increased with time up to 21 days in culture, irrespective of the medium composition. By day 14, the majority of neurons contained immunoreactive NSE in their cell bodies and fiber profiles. These data indicate that cultured embryonic neurons undergo differentiation in their serum-supplemented or serum-free medium, and that dissociated brain cell cultures may provide a model system for investigating cellular and molecular aspects of neuronal differentiation.

Production and characterization of monoclonal antibodies against the "brain-specific" proteins 14-3-2 and S-100

We have raised mouse hybridomas that secrete monoclonal antibodies against bovine brain-specific proteins 14-3-2 and S-100, and we have characterized the antibodies by immunoperoxidase and immunofluorescence methods in sections and in tissue cultures of rat brain. One monoclonal antibody to 14-3-2 (E8.F9) has been found to react strongly with bovine 14-3-2 and with rat neuron-specific enolase in an enzyme-linked immunosorbent assay (ELISA) and to react weakly with rat nonneuronal enolase. This pattern of specificity is reflected in strong neuronal labeling and occasional weak glial labeling in immunocytochemical preparations. After appropriate tissue fixation, E8.F9 could be shown to be localized primarily to the cytoplasm of neurons; with less adequate fixation nuclear labeling was also seen. A monoclonal antibody to the calcium binding protein S-100 (G12.B8) reacted strongly with bovine S-100 in an ELISA and with the major protein bands in electrophoretically separated S-100. In immunocytochemical preparations G12.B8 labeled the cytoplasm of astrocytes. Both antibodies are of the IgG1 subclass. Because of its specificity, the antibody against the S-100 protein promises to be useful as an immunological marker for astrocytes in the adult animal and in mature tissue cultures of brain cells. Although it has been thought that the generally low levels and relatively late appearance of S-100 during ontogeny may restrict its usefulness as a marker for developing astrocytes, preliminary immunocytochemical evidence indicates that G12.B8 selectively labels radial glial cells and astrocytes or astrocyte precursors as early as, or even earlier than, antibodies against the glial fibrillary acidic protein. The antibody against neuron-specific enolase is likely to be of limited use as a neuronal marker because of its crossreactivity with nonneuronal enolase.

Isolation and identification of neuroblast precursor cells from mouse neopallium

In this paper we describe the isolation of mouse neopallial neuroblast precursors using colony cultures and density gradients. The differentiation of neuroblast precursors was studied in tissue culture and after transplantation to the cerebellums of neonatal mice. In culture, survival of these cells is dependent on astroblasts, and their differentiation is incomplete. In the cerebellum, however, the cells give rise to neurons that correspond closely to the pyramidal cells and interneurons of mouse cerebral cortex according to morphometric measurements.

Nerve growth factor, laminin, and fibronectin promote neurite growth in human fetal sensory ganglia cultures

The effect of mouse nerve growth factor (NGF) on cultured human fetal sensory neurons was assayed by measuring neurite length, density and rate of growth. Addition of NGF increased adhesion of dissociated sensory neurons cultured on collagen coated surfaces. Almost all neurons of 9 to 10 week old fetuses are postmitotic, contain neuron-specific enolase, (an enzyme linked to differentiation), and require NGF for optimal neurite growth. Sensory ganglia re-explanted on collagen showed maximal neurite length and density when treated with 1 ng/ml of NGF. Neurite density was reduced considerably in the absence of mouse NGF and was almost abolished by addition of antimouse NGF antibodies. Surfaces coated with the matrix glycoproteins laminin or fibronectin further stimulated neurite growth of ganglia in the presence of NGF. Increasing amounts of matrix proteins could partly compensate for the absence of mouse NGF or the inhibition of NGF activity by antibodies. Stimulation of neurite growth by matrix proteins was time-dependent, and neurites showed maximum length at 10 days (2 to 3 mm). Neurite growth was more pronounced with laminin than with fibronectin and collagen, and antibodies to laminin suppressed all neurite growth. In the presence of a constant amount of NGF, mean neurite growth reached 26 microns/hr (at 1 day), and was 2.1 and 1.7 times faster on laminin and fibronectin (respectively) than on collagen. Thus, laminin, and to a lesser degree fibronectin, may enhance neurite growth of human sensory neurons in synergy with NGF.