Neurons switch from non-neuronal enolase to neuron-specific enolase during differentiation

Protein kinase C activation and down-regulation in relation to phorbol ester-induced differentiation of SH-SY5Y human neuroblastoma cells

The role of protein kinase C activation in changes in muscarinic receptor functions and in the appearance of biochemical properties characteristic of neuronal cells was studied in SH-SY5Y human neuroblastoma cells induced to differentiate with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). A decrease in muscarinic receptor sensitivity with respect to agonist induced Ca2+ mobilization and receptor number parallelled the increase in membrane-associated protein kinase C (PK-C) activity. These changes occurred during the first 6 h of culture, and they were associated with rounding-up of cells. A subsequent decrease in particulate PK-C activity was followed by an increase in noradrenaline content, the appearance of an electrically excitable membrane, and an increase in the level of neuron-specific enolase. These changes were accompanied by a pronounced neurite outgrowth. 1-(5-Isoquinolinesulphonyl)-2-methylpiperazine (H-7), an inhibitor of PK-C and cyclic nucleotide-dependent protein kinases, enhanced the morphological differentiation induced by TPA, whereas N-(2-guanidinoethyl)-5-isoquinolinesulphonamide (HA-1004), which primarily inhibits cyclic nucleotide-dependent protein kinases, had no effect on the TPA-induced phenotypic differentiation. H-7 inhibited the decrease in muscarinic receptor sensitivity and receptor number, but had no effect on the appearance of the electrically excitable membrane or on the increase in the neuron-specific enolase level. Both H-7 and HA-1004 inhibited the TPA-induced increase in noradrenaline content.

Clinical biochemistry of neuron specific enolase

The soluble brain protein 14-3-2 first described by Moore and McGregor in 1965 is now known to be a cell specific isoenzyme of the glycolytic enzyme enolase (EC 4.2.1.11), designated neuron specific enolase (NSE). It is not only a marker for all types of neurons, but also for all neuroendocrine or paraneuronal cells. The appearance of NSE is a late event in neural differentiation, thus making NSE a useful index of neural maturation. The demonstration that tumors of the nervous system and of neuroendocrine origin contain NSE has promoted the study of NSE as a possible tumor marker. Immunocytochemistry has been used to identify NSE in cytologic preparations from several types of tumors, offering useful indications for differential diagnosis. NSE levels in serum from tumor patients are not useful in the diagnosis of early stage disease. However, serum NSE levels have been shown to be helpful in the identification of advanced small cell lung cancer, neuroblastoma and several other neoplasms. The main use of serum NSE is the monitoring of chemotherapy and the detection of a relapse in these cases.

Cloning, expression and sequence homologies of cDNA for human gamma enolase

The nucleotide sequence of the human gamma-enolase mRNA was determined from recombinant cDNA clones. The sequence spans 2273 bp and includes the complete coding region of 1299 bp, a 5'-noncoding region of 74 bp and a 897-bp-long 3'-noncoding region containing a variant polyadenylation signal (ATTAAA). The deduced amino acid (aa) sequence is 433 aa long and shows a 97% similarity with rat gamma-enolase. Both the 5'- and 3'-untranslated regions are similar (82% and 68%, respectively) to the analogous regions of the rat gamma-enolase gene, suggesting that a strong selective pressure operates on noncoding segments of gamma-enolase mRNAs. The size of the gamma-enolase mRNA expressed in human brain is 2.4 kb. A crosshybridizing 1.5-kb message is detected in human skeletal muscle which may be derived from the beta-enolase-coding gene.

Development of the cerebellum with particular reference to cellular differentiation in the external granular layer

Immunocytochemical evidence of differentiation in developing human cerebellum is presented in this study. Antibodies to neuron specific enolase, neurofilament protein, glial fibrillary acidic protein, vimentin, cytokeratin, epithelial membrane antigen and lymphoid markers, DLC and Leu 7 were used. The external granular layer showed positivity with neuronal markers between 27 weeks gestation and 4 months postnatal, but was negative for all other markers including glial fibrillary acidic protein. Characteristic staining reactions were noted in the other cerebellar layers. Monoclonal antibodies, UJ13A (pan-neuroectodermal marker) and G10 (localising microtubule-associated protein MAP1x) were also used in a limited number of cryostat sections and were positive and negative, respectively, in the external granular layer. The results of this study are discussed in relation to the theory that the external granular layer may be one source of medulloblastomas.

The development of laminar staining for neuron-specific enolase in the rat somatosensory cortex

The expression of the enzyme neuron-specific enolase (NSE) in the central nervous system (CNS) has been used as a developmental marker based on observations that it is expressed shortly after the arrival of afferent inputs. The immunostaining pattern of NSE was examined in the laminae of the somatosensory cortex of the rat and the relationship of this staining pattern with previous data on the timing of afferent and efferent arrival was determined. Male rat pups were sacrificed on postnatal days 1 (24 h after birth), 3, 5, 8, 10, 12, 15 and 20, and as an adult (over 90 days of age). Sections were stained with an anti-NSE antibody using the avidin-biotin immunocytochemical method. Sections from day 1 animals revealed stained cells in the subplate layer and cortical plate, presumably in cells destined to form layers VI and V. By day 8 there was staining in layers II, III, V and VI, the same layers that exhibited staining in the adult rat. This appears consistent with the arrival of afferents and efferents which is completed by approximately postnatal day 7. On day 10, there was a change in the staining pattern: cell staining in layer VI was decreased and then increased gradually up to adult levels by day 20. A stable pattern of NSE staining was not observed previous to day 20. These results suggest that changes in NSE expression following the initial arrival of afferents may relate to maturation of the neurons.

An immunoblot assay for the simultaneous quantification of several antigens

A radioimmunologic assay method that allows for the simultaneous quantification of several antigens in one sample is described. Polypeptide antigens are resolved electrophoretically and electroblotted to nitrocellulose. The nitrocellulose is then reacted with a mixture of several antisera simultaneously, and antibody-binding proteins are visualized by incubation with 125I-protein A and by autoradiography. Antigens are identified according to their molecular weights and quantified by counting the bound radioactivity. The sensitivity of the assay is in the low nanogram range and can be adjusted individually for each antigen by appropriately diluting the first antiserum. The procedure is presently applied to the detection of three neural antigens, neural cell adhesion molecule, neuron-specific enolase, and synaptophysin, in adult brain tissue and to the assessment of expression of the latter two during development of brain cells in primary culture. The method is fast, comparatively cheap, and associated with a low radiation exposure. It should prove especially useful when only scarce amounts of sample are available.

Differentiation in medulloblastomas and other primitive neuroectodermal tumours

Fifty-four cases of primitive neuroectodermal tumour (PNET) including 47 medulloblastomas, were examined for evidence of neuronal and glial differentiation, using antibodies to neuron-specific enolase (NSE), neurofilament protein (NF), and glial fibrillary acidic protein (GFAP). In 30 of the cases, antibodies to vimentin, alphafetoprotein, cytokeratin, epithelial membrane antigen and lymphoid markers were also used. Most of the 47 medulloblastomas in the group were NSE positive but NF negative; about half were GFAP positive and three of them were positive for both neuronal markers and for GFAP. Vimentin was demonstrated in four cases and was not always co-expressed with GFAP. Medulloblastomas were negative for all the other markers. Supratentorial PNETs were sometimes positive with neuronal markers but were GFAP negative. The cell specificity of these markers and the interpretation of immunocytochemical findings are discussed in relation to differentiation potential in primitive neuroectodermal tumours.

Paragangliomas: assessment of prognosis by histologic, immunohistochemical, and ultrastructural techniques

To predict clinical outcome, we studied 42 paragangliomas from 37 patients by routine histology, immunohistochemistry, and electron microscopy. A panel of antisera to neuron-specific enolase (NSE), chromogranin, and met-enkephalin was used to identify chief (type I) cells, and S-100 protein and glial fibrillary acid protein (GFAP) sustentacular (type II) cells. The intensity of staining of type I cells and the density of type II cells were assessed semiquantitatively (0 to 4+) in a total of 38 tumors. A total of 23 of 24 low-grade tumors (solitary, multiple, or associated with other neoplasms; 95.8%) contained type II cells immunoreactive with either S-100 protein or GFAP, and all were positive when S-100 protein and GFAP were used in combination. Five of the nine intermediate-grade (recurrent and/or locally aggressive) tumors were identified as glomus jugulare tumors (GJT). Three intermediate-grade GJTs were devoid of GFAP-reactive type II cells and four GJTs were negative for S-100 protein. Type II cells were identified in only one of five high-grade (malignant) paragangliomas and that tumor contained vanishingly rare cells that were weakly S-100 protein positive but GFAP negative. Sustentacular cell density and chief cell staining intensity were both inversely related to tumor grade. The most sensitive chief cell marker was NSE (92.1%), followed by chromogranin (84.2%). The least sensitive (73.0%) and specific marker was met-enkephalin. Combinations of NSE or chromogranin with met-enkephalin identified chief cells in all cases. Electron microscopy identified neurosecretory granule-containing chief cells, but was of less value in delineating sustentacular cells because of their scarcity and the absence of specific features. By comparison, immunohistochemistry was superior in identifying sustentacular cells. The use of an immunohistochemical panel, in addition to routine histology, can confirm the diagnosis of a paraganglioma and can give an indication of the likely prognosis for a patient.

Ontogeny of the GTP-binding protein Go in rat brain and heart

We determined the ontogeny of the GTP-binding protein Go in rat brain and heart by employing highly sensitive enzyme immunoassay methods. In the brain, the alpha subunit of Go (Go alpha) gradually increased and reached adult levels approximately 20 and 30 days after birth in cerebral cortex and cerebellum, respectively. Concentrations of beta subunits, which were also quantified by the immunoassay, were almost equal to those of Go alpha in the brain of rats younger than 10 days, but were higher than those of Go alpha after 10 days. These results suggest that late development of GTP-binding proteins other than Go. Go alpha was immunohistochemically positive in neuropils and negative in cell bodies at any age tested. In the heart, the concentrations of Go alpha increased up to several times of the adult level just after birth, and then gradually decreased after the 20th postnatal day. The level of Go alpha in the liver, however, was very low and constant throughout ontogenic development. An immunohistochemical study indicated that Go alpha was positive in the cardiac muscle of young rat, but negative in that of adult rat. These results indicate that Go alpha exists in cells other than those of nervous tissues and neuroendocrine cells in some periods of ontogenic development.

Melanotic neuroectodermal tumour of infancy (MNTI). Immunohistochemical and ultrastructural study of a case

A case of melanotic neuroectodermal tumour of infancy (MNTI) which occurred in the left lower jaw of a 15-months old child was studied by electron microscopy and immunohistochemical methods to verify the neural crest origin of this tumour. Two cell population were observed: pigment melanocyte-like cells and non-pigmented nerve-like cells. Immunohistochemical analysis with neuron-specific enolase (NSE) and S-100 protein visualized two cell subtypes in the non-pigmented cell population. The combined ultrastructural findings and immunohistochemical data confirm the neural crest origin of MNTI.

Neuronal and glial markers of the central nervous system

This brief review evaluates the expression of cell-specific markers on differentiated neural cells and, where necessary, on their developing precursors. Within these limitations only the commonly used markers are discussed and those deemed unequivocal are only briefly appraised.

Development of parasagittal zonation in the rat cerebellar cortex: MabQ113 antigenic bands are created postnatally by the suppression of antigen expression in a subset of Purkinje cells

Monoclonal antibody mabQ113 recognizes a polypeptide antigen that, in the adult cerebellum, is confined to a subset of Purkinje cells that are clustered together to form parasagittal bands interposed by similar nonimmunoreactive bands. The Purkinje cell compartments are congruent with bands of climbing fibers projecting from subregions of the inferior olivary complex (IOC). The array of mabQ113 parasagittal bands appears late in the development of the cortex. Weak mabQ113 immunoreactivity is first seen at postnatal day 6 (P6) in the Purkinje cells of the posterior lobe of the vermis. From the earliest stages there are signs of differential expression of the mabQ113 antigen in clusters of Purkinje cells: four mabQ113+ clusters are clearly present in the posterior lobe of the vermis at P6-P7. Their relation to the adult band display remains uncertain. During the next few days immunoreactivity spreads rostrally throughout the rest of the vermis and laterally to include the Purkinje cells in the hemispheres, until by P12 all the Purkinje cells in the cerebellum are mabQ113+. Nevertheless, signs of the adult band display are seen already in the vermis where the cells destined to become the vermal mabQ113+ bands (P1+, P2+ and P3+) stain more intensely than their neighbours. Following the stage of global mab113 epitope expression, bands are created by the selective suppression of immunoreactivity by Purkinje cells in the P- regions. By P15 the mabQ113+ and mabQ113- bands are clearly differentiated in the vermis and selective staining has begun to appear in the hemispheres also. The band pattern matures gradually during the third and fourth postnatal weeks until the adult appearance is attained by P30. The cerebellar afferent projections were lesioned to explore the interplay of cerebellar input and mabQ113 expression. The olivocerebellar projection was lesioned bilaterally by using 3-acetylpyridine in the adult and unilaterally in the newborn by electrolytic lesion and unilateral inferior cerebellar pedunculectomy. Mossy fibers from the dorsal and ventral spinocerebellar tracts were lesioned surgically both in adults and in newborn and trigeminal projections to the cerebellum were removed in the newborn by unilateral ablation of the spinal trigeminal nucleus. The consequences of total blockage of vibrissal and hindlimb inputs were also explored in both adults and neonates. None of these treatments led to a modification in the pattern of mabQ113 epitope expression.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Expression of c-src in cultured human neuroblastoma and small-cell lung carcinoma cell lines correlates with neurocrine differentiation

Human cell lines with neuronal and neuroendocrine features were examined for their expression of pp60c-src, the cellular homolog of the transforming gene product pp60v-src of Rous sarcoma virus. Four neuroblastoma (LA-N-5, SH-SY5Y, Paju, and SK-N-MC) and three small-cell lung carcinoma (U-2020, U-1690, and U-1285) cell lines were selected on the basis of their stage of neurocrine differentiation, as determined by the expression of neuron-specific enolase. In an immune complex protein kinase assay, all seven cell lines displayed c-src kinase activity which was considerably higher than that found in nonneurocrine cells (human diploid fibroblasts, glioma, and non-small cell lung carcinoma cell lines). Furthermore, the c-src kinase activity, as determined by autophosphorylation or phosphorylation of an exogenous substrate, enolase, correlated with the stage of neurocrine differentiation. There was an approximately 30-fold difference in c-src kinase autophosphorylation activity between the cell lines representing the highest and lowest stages of neurocrine differentiation. A similar variation was found in the steady-state levels of the c-src protein of these cell lines. Highly differentiated neuroblastoma cells expressed two forms of the src protein. Digestion by Staphylococcus aureus V8 protease did reveal structural diversity in the amino-terminal ends of these c-src molecules. In summary, we found a clear correlation between c-src kinase activity and the stage of neuronal and neuroendocrine differentiation. Thus, the phenotypic similarity between neurons and neuroendocrine cells includes high c-src expression.

Go, a GTP-binding protein: immunochemical and immunohistochemical localization in the rat

The tissue and cellular distribution of a GTP-binding protein, Go, was investigated in the rat by immunochemical and immunohistochemical methods. Because the specific antibody for the alpha subunit of bovine Go (Go alpha) cross-reacted with rat Go alpha, an enzyme immunoassay method developed for bovine Go alpha was applied for measuring the tissue concentration of Go alpha in the rat. Go alpha was detected in all tissues examined except blood cells. The concentration of Go alpha was highest in the CNS (approximately 7.7 and 4.4 nmol/g in the cerebrum and cerebellum, respectively), followed by the pituitary gland and sciatic nerve. Among the other peripheral tissues, relatively high concentrations of Go alpha were observed in the urinary bladder, stomach, and intestines; however, these values were less than 2% of the concentration in the cerebrum. Go alpha in the intestine was located mostly in the muscle layer. Immunohistochemical study showed that Go alpha was associated mostly with the neural elements but not with cells particular to each peripheral organ. Go alpha was also present in the membranes of neuroendocrine cells, including glandular cells in the anterior lobe of the pituitary gland, chromaffin cells in the medulla of the adrenal gland, islets cells in the pancreas, and parafollicular cells in the thyroid. These results indicate that Go is localized exclusively in the nervous tissues and neuroendocrine cells.

Reciprocal age-dependent pattern of two neuronal markers, tetanus toxin and neuron-specific enolase, in postnatal rat sensory and sympathetic neurons

Tetanus toxin (TT) and antibodies to neuron-specific enolase (NSE) were used to study the developmentally regulated expression of two neuronal markers in isolated and short-term cultured rat sensory and sympathetic neurons at different postnatal ages. The results show a reciprocal pattern of TT binding and NSE-immunoreactive neurons during postnatal maturation: there is a gradual transition from TT-positive, NSE-negative to TT-negative, NSE-positive phenotypic expressions. We conclude that TT may serve as a neuronal marker for newborn, anti-NSE antibodies as markers for adult neurons, and a combination of both for adolescent neurons.

Comparative study of glial marker proteins in the hypoplastic cerebellum of jaundiced Gunn rats

The behavior of marker proteins of glial cells [alpha-enolase, beta-S100 protein, and glial fibrillary acidic protein (GFAP)] was investigated quantitatively by using enzyme immunoassay systems during the development of cerebellar hypoplasia in jaundiced Gunn rats. A neuronal marker protein, gamma-enolase, was also measured as a reference. At postnatal day 8 corresponding to the early stage of cerebellar damage, the amount of beta-S100 on a protein basis was significantly higher in jaundiced homozygotes (jj) than in control nonjaundiced heterozygotes (j+), whereas no differences in alpha- and gamma-enolases and GFAP were observed between the two groups of rats. At days 15 and 30, which correspond, respectively, to the advanced and late stages of cerebellar damage, the three glial proteins, especially GFAP, were higher and the neuronal protein was lower in the jj rat cerebellum than in the control. These results are consistent with the reported histological observations that neuronal cells are vulnerable and damaged by bilirubin, whereas glial cells seem to be less sensitive. On the other hand, the amounts of beta-S100 and alpha-enolase per cerebellum were significantly lower in jj rats at days 15 and 30, as in the case of gamma-enolase, whereas that of GFAP remained at the same level as the control at day 15 and showed a slight but significant decrease at day 30. The possibility is suggested that beta-S100 and GFAP may be available as biochemical indicators of glial cells, especially in the early and advanced stages of cerebellar damage, respectively, but that alpha-enolase is less available.

Glycine-like immunoreactivity in the rat auditory pathway

From neurophysiological and biochemical studies it has been suggested that glycine can function as a major inhibitory neurotransmitter in the central nervous system of mammals. In the present study, anti-glycine antiserum was obtained from rabbits immunized with glycine conjugated to rabbit serum albumin via glutaraldehyde and purified by affinity chromatography. The antibody thus obtained was found specific for glycine as determined by an enzyme immunoassay system. The immunocytochemical distribution of glycine in the auditory tract and internal ear was investigated with the antibody. In the central auditory pathway, glycine-like immunoreactivity was mainly located in the ventral and dorsal cochlear nuclei, trapezoid body, lateral lemniscus and inferior colliculus. In the labyrinth, immunoreactivity was detected in the vestibular ganglion and the supporting cells of the crista ampullaris and the organ of Corti, but not in the spiral ganglion. These findings suggest an important role of glycine in the auditory and vestibular pathways.

Development of the notochord in human embryos: ultrastructural, histochemical, and immunohistochemical studies

In the present study of the notochord, the specimens were 54 externally normal human embryos ranging between Carnegie stages 13 and 23. The following staining procedures were used: periodic acid-Schiff (PAS), modified method of PAS, alcian blue, colloidal iron, and toluidine blue. Routine electron microscopic techniques were used. Immunoreactivity of the notochord to alpha-enolase was also examined. The notochord cells were undifferentiated in stage 13 with few intracellular organelles. The microfibrils and deposition of acid mucopolysaccharides appeared in the notochordal sheath in stage 14. The characteristic relation of mitochondria with rough endoplasmic reticulum was observed. Golgi complexes increased in the perinuclear region in stage 15. The layer of microfibrils in the notochordal sheath initially separated from the notochord in stage 16. Glycogen, mucoprotein, neutral mucopolysaccharides, and glycolipids began to increase in the mesenchymal cells around the notochord, starting at stage 16. Acid mucopolysaccharides increased in the notochordal sheath and in the matrix of the precartilage area around the notochord as this embryonic stage advanced. It was also revealed that the immunoreactivity of the notochord to alpha-enolase remained constant during the embryonic period. The results show that the notochord is transformed from an apparently undifferentiated organ into an organ with secretory activity in stage 14, producing microfibrils and depositing acid mucoplysaccharides in the notochordal sheath. The immunoreactivity of the notochord to alpha- and gamma-enolase isoenzymes and the development of the notochord are discussed. This study was undertaken to provide additional information on the development of tumors of notochordal origin.

Characterization of neurotransmitter phenotype during neuronal differentiation of embryonal carcinoma cells

Embryonal carcinoma cells are useful in the study of embryogenesis and development, and their differentiation into neurons serves as a model of neuronal development. Retinoic acid was used to differentiate P19S18O1A1 embryonal carcinoma cells into neuronal, glial, and fibroblast-like cells and the phenotype of the neuronal population was examined. Neuron-specific enolase was present in the neuronal cells, suggesting that these neurons had reached some degree of maturity. A population (approximately 70%) of the neurons showed positive immunocytochemistry for tyrosine hydroxylase, dopamine beta-hydroxylase and phenylethanolamine N-methyltransferase, three enzymes in the pathway of catecholamine synthesis. Therefore a population of the neurons appeared to be adrenergic. These neurons also showed a low level of histofluorescence for endogenous catecholamines and exhibited an exogenous catecholamine reuptake system. In order to determine the phenotype of other neuron-like cells found to be negative for the adrenergic properties examined, immunocytochemistry for neuropeptides and neurotransmitters known to coexist within central neurons was performed. Serotonin, vasoactive intestinal peptide, glutamic acid decarboxylase, and choline acetyltransferase were all absent from retinoic acid-treated P19S18O1A1 neuronal cultures. These studies, along with those that compare the effects of retinoic acid and other growth modulators on neuronal differentiation of embryonal carcinoma cells, should aid in the understanding of neuronal induction and development in vivo.

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.

Developmental effect of dimethyl sulfoxide on hypothalamo-neurohypophysial neurons in vitro

Primary dissociated cultures were established from diencephalic tissue of 14-day-old fetal rats. Neurons exhibiting immunocytochemical staining for neurophysin appeared in these cultures after 6 days of cultivation. Addition of dimethyl sulfoxide (DMSO) to the culture medium resulted in a slight decrease in total neuronal cell mass as assessed by immunocytochemistry and radio-immunometric quantitation of neuron-specific enolase. In contrast, in DMSO-treated cultures the number of neurophysin-immunoreactive neurons was more than doubled as compared to control cultures. [3H]Thymidine labeling and autoradiography in conjunction with immunocytochemistry for neurophysin showed that this was not due to a mitogenic effect of DMSO on precursor cells. Time-course analysis of the action of DMSO revealed a 6-day time lag between the initiation of treatment and the appearance of increased numbers of neurophysin-immunoreactive cells. These findings suggest that DMSO, which has previously been reported to have a differentiation-inducing effect on malignant transformed cells, may also modulate cellular processes that control differentiation in specific types of neurons in primary culture.

Expression of c-src in cultured human neuroblastoma and small-cell lung carcinoma cell lines correlates with neurocrine differentiation

Human cell lines with neuronal and neuroendocrine features were examined for their expression of pp60c-src, the cellular homolog of the transforming gene product pp60v-src of Rous sarcoma virus. Four neuroblastoma (LA-N-5, SH-SY5Y, Paju, and SK-N-MC) and three small-cell lung carcinoma (U-2020, U-1690, and U-1285) cell lines were selected on the basis of their stage of neurocrine differentiation, as determined by the expression of neuron-specific enolase. In an immune complex protein kinase assay, all seven cell lines displayed c-src kinase activity which was considerably higher than that found in nonneurocrine cells (human diploid fibroblasts, glioma, and non-small cell lung carcinoma cell lines). Furthermore, the c-src kinase activity, as determined by autophosphorylation or phosphorylation of an exogenous substrate, enolase, correlated with the stage of neurocrine differentiation. There was an approximately 30-fold difference in c-src kinase autophosphorylation activity between the cell lines representing the highest and lowest stages of neurocrine differentiation. A similar variation was found in the steady-state levels of the c-src protein of these cell lines. Highly differentiated neuroblastoma cells expressed two forms of the src protein. Digestion by Staphylococcus aureus V8 protease did reveal structural diversity in the amino-terminal ends of these c-src molecules. In summary, we found a clear correlation between c-src kinase activity and the stage of neuronal and neuroendocrine differentiation. Thus, the phenotypic similarity between neurons and neuroendocrine cells includes high c-src expression.

Immunohistochemistry of retinoblastomas

Immunohistochemical stains using neuronal and glial marker proteins were applied to retinoblastomas tissues from 14 children. Among the neurofilament triplet proteins, NF68Kd positive cells were observed in 12. Few NF160Kd positive cells were noted in 2, and NF210Kd positive cells were not detected. The positive ratio of NF68Kd and gamma-enolase seems to relate to the Flexner-Wintersteiner rosettes. Gamma-enolase positive cells were observed in 13. The distribution in tumor tissues was broader than that of NF68Kd positive cells. The immunoreactivities of NF68Kd were in parallel with those of gamma-enolase. Few GFAP positive cells were present around blood vessels, while S-100 protein and MBP positive cells were never observed. Our results indicate that retinoblastoma possesses predominantly neuronal properties, albeit in an immature form.

Purification of specific antibody against aspartate and immunocytochemical localization of aspartergic neurons in the rat brain

The distribution of L-aspartate known as a putative excitatory neurotransmitter in the central nervous system was investigated immunocytochemically in the rat brain. Anti-aspartate antiserum was raised in rabbits using L-aspartate covalently conjugated to rabbit serum albumin with glutaraldehyde as the immunogen and was found to be cross-reactive with an L-glutamate conjugate. Monospecific anti-L-aspartate antibody was successfully purified using affinity gels coupled with several amino acids including L-aspartate and L-glutamate and with the L-glutamate conjugate. Putative aspartergic neurons were generally immunoreactive to the purified antibody, but epithelia of the choroid plexus were also stained. These results show that the antibody is a useful tool for the immunocytochemical demonstration of possible aspartergic neurons in the central nervous system, although the immunochemical expression of L-aspartate not used as a neurotransmitter must be taken into consideration.

Localization of neuron-specific enolase (NSE) mRNA in human brain

In situ hybridization with biotinylated DNA and RNA probes derived from the 3' untranslated region of human neuron-specific or gamma gamma-enolase (NSE) permits histochemical detection of NSE mRNA in autopsy samples of human brain. In both aged controls and Alzheimer's disease (AD) patients, NSE probe hybridized with variable intensity to nerve cells in visual cortex and cerebellum, but not to glial or liver cells. These results provide evidence that NSE mRNA is expressed in neurons in human brain tissue, pattern of NSE mRNA expression in unaffected brain regions in AD is qualitatively normal, and NSE mRNA expression may vary widely among different classes of neurons.

Highly sensitive immunoassay for the alpha subunit of the GTP-binding protein go and its regional distribution in bovine brain

Antisera were raised in rabbits against the alpha subunit of a GTP-binding protein, Go. Because the antisera cross-reacted weakly with the alpha subunit of inhibitory GTP-binding protein of adenylate cyclase (Gi), they were purified with a Go alpha-coupled Sepharose column. Purified antibodies reacted only with Go alpha and did not cross-react with the Gi alpha subunit or beta gamma subunits in an immunoblot assay. Using these purified antibodies, a highly sensitive enzyme immunoassay method for the quantification of bovine brain Go alpha was developed. The assay system consisted of polystyrene balls with immobilized antibody F(ab')2 fragments and the same antibody Fab' fragments labeled with beta-D-galactosidase from Escherichia coli. The minimal detection limit of the assay was 0.1 fmol, or 4 pg. The assay was specific for Go alpha, and it did not cross-react with Gi alpha or beta gamma. Samples from various regions of bovine brain were solubilized with 2% sodium cholate and 1 M NaCl, and the concentrations of Go alpha were determined. Go alpha was detected in all the regions, and the highest concentration was observed in the cerebral cortex. The immunohistochemical study showed that the neuropil was rich in Go alpha.

Neuronal maturation in the normal and hypothyroid rat cerebellar cortex studied with monoclonal antibody MIT-23

By immunocytochemistry we have studied the expression of the mitochondria-associated polypeptide MIT-23 during the postnatal development of the normal and hypothyroid rat cerebellar cortex, in afferent fibers, and also in neurons of the cerebellar nuclei. The glial cells are never immunoreactive. In all neurons of the cerebellar cortex, MIT-23 expression always occurs after the final mitosis and migration are complete, and persists throughout adult life. Almost all MIT-23 expression begins postnatally. A few Purkinje cells are already immunoreactive at birth and the rest begin expression during the following two days. Immunoreactive Golgi and granule cells are found from postnatal day 4 (P4), basket cells from P10, and stellate cells from P16. Purkinje cells from different anteroposterior regions of the vermis express different levels of MIT-23 with higher staining intensities in lobules I to IV. These differences appear early in development and are retained in the adult. MIT-23 expression in the hypothyroid cerebellar cortex differs from that in control animals only in minor ways. However, sections immunoperoxidase-stained with anti-MIT-23 antibody reveal that, in addition to previously reported alterations in cerebellar development due to a shortage of thyroid hormones, Purkinje cell axonal development is slowed down in the hypothyroid condition, and occasional Purkinje cells in normal and especially in hypothyroid animals have their somata and or dendrites in ectopic locations. Analysis of these cells reveals a preferential direction of dendritic trunk growth in the direction of the molecular layer. Furthermore, secondary branching of ectopic dendrites is confined exclusively to the developing molecular layer, as in normal Purkinje cells, thus suggesting that neither the mature nor immature granule cell environment is sufficient to sustain normal dendritic 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.

Appearance and development of neuron-specific enolase immunoreactivity in organotypic cultures of mouse embryo otocysts

The appearance of neuron-specific enolase (NSE) immunoreactivity was studied in sensory and vestibular ganglion cells during the development of mouse embryo otocysts grown in vitro from the 13th gestation day. NSE appeared sequentially in the ganglion and sensory cell populations of the inner ear with a pattern that paralleled their successive maturation. Comparison with NSE immunoreactivity profile during in vivo development shows that NSE appears earlier during organotypic in vitro maturation.

Defective biosynthesis of proteolipid protein in Pelizaeus-Merzbacher disease

The brain of an 18-year-old patient with Pelizaeus-Merzbacher disease was examined by standard neuropathological and biochemical methods and by immunocytochemical and immunochemical techniques. Analysis revealed a lack of myelin-specific lipids, but showed a residual immunoreactivity for myelin basic protein, myelin-associated glycoprotein, and 2',3'-cyclic nucleotide-3'-phosphodiesterase. Examination by immunocytochemistry and enzyme-linked immunosorbent assay showed an absence of proteolipid apoprotein (lipophilin). The peripheral nervous system was normal. Pelizaeus-Merzbacher disease in humans shares many neuropathological and biochemical features with X-linked mutations in animals, e.g., the jimpy mouse and myelin-deficient rat. The specificity of this protein deficiency in Pelizaeus-Merzbacher disease gains additional support from the recent mapping of the lipophilin gene to the human X chromosome.

Hypothalamo-neurohypophysial neurons in vitro: developmental potentials depend on the donor rat stock

Primary dispersed cell cultures were established from fetal diencephalic tissue derived from two stocks of outbred rats. The overall growth pattern, as followed by phase-contrast microscopy and visualized by immunocytochemistry for neurofilament proteins and neuron specific enolase, depended on the age of the donor animal. Stock differences were not revealed by these methods. In contrast, when the cultures were immunostained in order to assess the yield of a specific type of cell, i.e., magnocellular hypothalamic neurons, striking differences were observed between the two stocks of rats. Whereas neurophysin-immunoreactive cells could be grown in cultures established from fetal Chbb: Thom rats at embryonic days 14, 15, and 18, no such cells could be detected in cultures derived from Crl: CD (SD) BR rats older than embryonic day 14. These findings may reflect differences in the differentiation schedule and/or requirements for certain epigenetic and trophic factors between magnocellular neuroblasts derived from the two stocks of rats.

Influence of mouse trisomy 16 on expression of specific genes

We examined developmental changes in the relative activities of three different isozyme systems: aldolase, enolase and phosphoglycerate mutase, in tissues of fetal mice with trisomy 16 and of fetal euploid littermates. We wanted to determine whether morphological abnormalities such as reduced weight and size, which are generally observed in murine trisomy, are reflected at the molecular level. Following electrophoretic separation and subsequent measurement of relative activities of enolase isozymes in brain and phosphoglycerate mutase isozymes in heart, we found no significant differences between trisomy 16 fetuses and their euploid littermates. Synthesis of liver-specific aldolase was, however, delayed in trisomy 16 fetuses.

Neuron-enriched cultures of adult rat dorsal root ganglia: establishment, characterization, survival, and neuropeptide expression in response to trophic factors

It is unknown whether adult dorsal root ganglion (DRG) neurons require trophic factors for their survival and maintenance of neuropeptide phenotypes. We have established and characterized neuron-enriched cultures of adult rat DRGs and investigated their responses to nerve growth factor (NGF), ciliary neuronotrophic factor (CNTF), pig brain extract (PBE, crude fraction of brain-derived neuronotrophic factor, BDNF), and laminin (LN). DRGs were dissected from levels C1 through L6 and dissociated and freed from myelin fragments and most satellite (S-100-immunoreactive) cells by centrifugation on Percoll and preplating. The enriched neurons, characterized by their morphology and immunoreactivity for neuron-specific enolase, constituted a population representative of the in vivo situation with regard to expression of substance P (SP), somatostatin (SOM), and cholecystokinin-8 (CCK) immunoreactivities. In the absence of trophic factors and using polyornithine (PORN) as a substratum, 60-70% of the neurons present initially (0.5 days) had died after 7 days. LN as a substratum did not prevent a 30% loss of neurons up to day 4.5, but it subsequently maintained DRG neurons at a plateau. This behavior might reflect a cotrophic effect of LN and factors provided by non-neuronal cells, whose proliferation between 4.5 and 7 days could not be prevented by addition of mitotic inhibitors of gamma-irradiation. CNTF, but not NGF, slightly enhanced survival at 7 days on either PORN or LN. No neuronal losses were found in non-enriched cultures or when enriched neurons were supplemented with PBE, indicating that non-neuronal cells and PBE provide factor(s) essential for adult DRG neuron survival. Proportions of SP-, SOM-, and CCK-immunoreactive cells were unaltered under any experimental condition, with the exception of a numerical decline in SP cells in 7-day cultures with LN, but not PORN, as the substratum. Our data, considered in the context of recent in vivo and vitro studies, suggest that a combination of trophic factors or an unidentified factor, rather than the established molecules NGF, CNTF, and BDNF, which address embryonic and neonatal DRG neurons, are required for the in vitro maintenance of adult DRG neurons.

Immunohistochemical identification of neuron-specific enolase and calbindin in the vestibular receptors of human fetuses

Immunohistochemical techniques were used to identify neuron-specific enolase (NSE) and calbindin in the vestibular receptors and ganglia of human fetuses at 10 weeks of gestation. NSE was found in vestibular ganglion cells and in a few sensory cells. The pattern of immunoreactivity in the sensory epithelia was characteristic of the appearance of NSE in these structures. Calbindin was found in vestibular ganglion cells and sensory cells which displayed a strong immunoreactivity. These findings are discussed with regard to synaptogenesis and they indicate that the vestibular receptors show biochemical signs of maturation consistent with the possibility of synaptic activity.

Selective localization of gamma-enolase in stromal cells of cerebellar hemangioblastomas

Three cases of cerebellar hemangioblastoma were studied using the immunoperoxidase technique to localize gamma-enolase, also known as neuron-specific enolase. The stromal cells demonstrated positive staining for gamma-enolase, while endothelial cells and pericytes showed no reactivity. Two vascular lesions, an angiosarcoma and a cutaneous angioma, were studied and found to be nonreactive for gamma-enolase. All tumors were also tested for factor VIII/von Willebrand factor, glial fibrillary acidic protein, and the S-100 protein. The lack of expression of gamma-enolase in endothelial cells of hemangioblastomas demonstrates a clear antigenic distinction from neighboring gamma-enolase-positive stromal cells. The significance of this finding and its implications for stromal cell histogenesis are discussed.

Isolation of murine neuron-specific and non-neuronal enolase cDNA clones

cDNA clones corresponding to subunits of neuron-specific (gamma gamma and alpha gamma) and non-neuronal (alpha alpha) enolase isozymes were characterized from two mouse brain cDNA libraries. Our hybridization data revealed a partial homology of the coding sequences of mouse alpha, mouse gamma and rat gamma mRNAs. The noncoding sequences, however, appear to be specific for each mouse mRNA. Although coding for two polypeptides of the same molecular weight, the mRNA for the gamma subunit (2600 bases) is larger than that for the alpha subunit (1900 bases). The noncoding sequences for neuron-specific gamma mRNA (about 1300 bases) are therefore longer than those of the non-nervous tissue specific alpha mRNA (about 600 bases).

Antineuron specific enolase staining reactions in sarcomas and carcinomas: its lack of neuroendocrine specificity

A commercially available polyclonal antiserum (Dakopatts) raised against bovine neuron specific enolase (NSE) was reacted with 197 sarcomas, 32 carcinomas, 11 carcinoid tumours and 20 malignant melanomas to assess its specificity for neuroendocrine tumours. All the tumours had been fixed in formalin and embedded in paraffin. Positive tumour cells were found in two of 11 squamous cell carcinomas, one of 11 adenocarcinomas, 10 of 10 oat cell carcinomas, 11 of 11 carcinoid tumours, 16 of 20 malignant melanomas, four of seven clear cell sarcomas, nine of 25 leiomyosarcomas, four of 22 rhabdomyosarcomas, one of seven angiosarcomas and one of 20 synovial sarcomas.

Immunohistochemical localization of gamma-enolase in early human embryos

gamma-Enolase has been believed to be distributed only in the neurons and it was frequently labelled as neuron-specific enolase. However, recent precise studies have suggested a wider distribution of the protein. It can also be found in neuroendocrine cells, some mesodermal tissues, and some malignant tumors originating from tissues without the antigen in a normal condition. In early rat embryos, before the formation of neural tissues, a sensitive immunoassay system revealed a substantial amount of gamma-enolase, though it is not yet clear where the antigen is located. In the present study, tissue distribution of gamma-enolase in early human embryos was studied using an immunohistochemical method and it was suggested that the protein is present not only in neural tissue primordium but also in most tissues in the youngest embryo of 6.3 mm crown-rump length. Many of the immunoreactive non-neural tissues, however, lost immunoreactivity with the advancement of the embryonic stage while neural tissues became more intensely stained. In the embryo of 24 mm length, the staining pattern was almost the same as that of reported adult men. In embryonic tissues such as notochord and mesonephros, which disappear in the due course of growth, the antigen was also found. These findings will suggest that the antigen is rather common in undifferentiated tissues but then localizes in neural elements with advancing age. Our findings may be useful in explaining why early rat embryos, before the formation of neural tissues, showed a considerable amount of gamma-enolase and why many undifferentiated tumors, originating from tissues which did not have the antigen in normal condition, revealed the antigen.

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.

New candidates for GABAergic neurons in the rat cerebellum: an immunocytochemical study with anti-GABA antibody

Cerebellar cortical neurons immunoreactive to anti-gamma-aminobutyric acid (GABA) antibody were examined in the rat. In addition to the Purkinje, Golgi, basket and stellate cells, spindle-shaped cells lying just below the Purkinje cell layer were found to be strongly immunoreactive to the antibody. By the combination of immunofluorescence and hematoxylin stainings, these GABA-positive cells were shown to be the Lugaro cells. Unlike the immunopositive small Golgi cell, the pale cell was not immunoreactive to the antibody.

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.

Varicella-zoster virus infection of human sensory neurons

Primary varicella-zoster virus (VZV) infection of humans may result in latent infection of sensory neurons in the peripheral nervous system. To examine the interaction of VZV with the sensory neuron we infected immunochemically defined human neurons with cell-associated VZV. Utilizing double-label immunofluorescence technology, a VZV-specific glycoprotein and a nonglycosylated phosphoprotein were detected in human fetus dorsal root ganglion (DRG) neurons, as defined by the presence of the neuron-specific enolase isoenzyme and the A2B5 ganglioside antigen, respectively. In addition to VZV antigen expression, progressive virus-induced cytopathic damage (neuronal enlargement and nuclear granulation of a fraction of the neuron population) was evident. As determined by transmission electron microscopy, VZV-infected human fetus DRG neurons contained empty and complete nucleocapsids with numerous pleomorphic virus particles in the cytoplasm, often in association with vacuoles. Although virus-specific antigen expression, particle synthesis, and cytopathic effects were observed in the human neuron population, neurons were less susceptible to VZV-induced cytopathic damage than supporting nonneuronal cells, suggesting neuronal modulation of VZV infection in vitro. This system provides the first model to examine the neuron- and virus-specific gene(s) and gene product(s) pertinent to the interaction of VZV with the human neuron.

Gamma-enolase activity in choroidal melanoma

Gamma-enolase is a glycolytic enzyme that is found in high concentration in neural and neuroendocrine tissues. The enzyme has been considered clinically useful as a tumor marker in the evaluation of small-cell undifferentiated malignancies. A preliminary report suggested that gamma-enolase activity may be used in the assessment of the malignant potential of choroidal melanoma. To test this hypothesis and document the distribution of gamma-enolase in the eye, we studied the immunohistochemical activity of gamma-enolase in six eyes from persons with choroidal melanoma. Although no correlation could be found with gamma-enolase activity and tumor size or tumor cell type, the distribution of gamma-enolase in normal retina and optic nerve was described. The areas of greatest immunohistochemical reactivity were the perikaryon of ganglion cells, inner and outer plexiform layers, and the nerve axons of the nerve fiber layer and optic nerve. Gamma-enolase may be a potentially useful marker of retinal and optic nerve glycolysis, and of neuronal function.

Highly sensitive immunoassay for rat brain-type creatine kinase: determination in isolated Purkinje cells

Ultrasensitive enzyme immunoassay method for the measurement of rat brain-type creatine kinase BB (CK-BB) was developed by use of purified antibodies specific to the B subunit of creatine kinase. The antibody immunoglobulin G was purified with immunoaffinity chromatography of the antiserum raised in rabbits by injecting the purified rat CK-BB. The assay system consisted of polystyrene balls with immobilized antibody F(ab')2 fragments and the same antibody Fab' fragments labeled with beta-D-galactosidase from Escherichia coli. The assay was specific to the B subunit of CK (CK-B), showing about 10% cross-reactivity with CK-MB, but it did not cross-react with CK-MM and neuron-specific gamma gamma enolase. The minimum detection limit of the assay was 0.1 pg or 1 amol CK-BB, being sufficiently sensitive for the measurement of CK-B contents in the isolated Purkinje cell bodies at the level of single cells. The average content of CK-B in a single Purkinje cell was 1.64 pg. The CK-B concentration in rat cerebellum (about 22 micrograms/mg protein) was about twofold higher than that (about 13 micrograms/mg protein) in the cerebrum. High levels (greater than 5 micrograms/mg protein) of CK-B were also found in the peripheral tissues such as gastrointestinal tract and urinary bladder, all of which are composed of smooth muscle. Immunohistochemical localization of CK-B antigens in the CNS revealed that the antigens is distributed not only in the neurons but also in the glial cells.