The cardiac sodium channel mRNA is expressed in the developing and adult rat and human brain

Expression of the rat (RH-I/SkM2) and human (hH1/SCN5A) tetrodotoxin-resistant (TTX-R), voltage-sensitive sodium channels is thought to be specific to cardiac tissue. We detected RH-I/SkM2 mRNA in newborn rat brain using both RNase protection assay analysis and in situ hybridization and in adult rat brain using RNase protection assay analysis. This expression was observed primarily in developing limbic structures of the cerebrum and diencephalon, and in the medulla of the brain stem. Using RT-PCR analysis, we detected hH1/SCN5A mRNA in both fetal and adult human brain. Interestingly, mutations in the human cardiac sodium channel are known to lead to cardiac abnormalities, which result in arrhythmias and frequently in sudden cardiac death. If these mutant channels were also expressed in limbic regions of the brain, alterations in channel function could have drastic effects on the brain's signaling ability, possibly promoting seizure activity.

Myelinated fibers of spinal cord blood vessels--sensory innervation?

Innervation of the ventral spinal artery from the lumbosacral region of dogs was studied using light, scanning, and transmission microscopy. Microscopy revealed myelinated fibers, a new observation, in addition to unmyelinated fibers expected on the basis of previous studies of autonomic innervation of this blood vessel. The myelinated axons may be sensory fibers.

Characterization of developmental stage and neuronal potential of the rat PNS-derived stem cell line, RT4-AC

RT4 is a family of cell lines derived from a rat peripheral neurotumor and consists of a multipotential stem cell line that spontaneously gives rise to three derivative cell types: one glial-like and two neuronal-like. Previous studies have established that the RT4 glial derivative expresses many properties of Schwann cells; however, the neuronal designation of the other RT4 derivatives is less well substantiated. To further characterize the developmental stage and lineages represented by the RT4 stem cell and its derivatives we examined the expression of 16 marker genes whose expression is either specific to neurons or in some cases, neural tissue. Taken together our results indicate that (i) the RT4 neuronal-like derivatives express only immature neuronal properties, (ii) the RT4 cell lines most closely resemble neural crest derivatives from embryonic day 10 to 12 in the rat, (iii) treatment with cAMP and steroids, although capable of promoting process extension by the RT4 neuronal-like derivatives, did not affect the expression of any of the 16 marker genes examined, and (iv) when compared to other neural stem cell systems, RT4-AC generates the most immature neuronal derivatives.

Survival and differentiation of adult neuronal progenitor cells transplanted to the adult brain

The dentate gyrus of the hippocampus is one of the few areas of the adult brain that undergoes neurogenesis. In the present study, cells capable of proliferation and neurogenesis were isolated and cultured from the adult rat hippocampus. In defined medium containing basic fibroblast growth factor (FGF-2), cells can survive, proliferate, and express neuronal and glial markers. Cells have been maintained in culture for 1 year through multiple passages. These cultured adult cells were labeled in vitro with bromodeoxyuridine and adenovirus expressing beta-galactosidase and were transplanted to the adult rat hippocampus. Surviving cells were evident through 3 months postimplantation with no evidence of tumor formation. Within 2 months postgrafting, labeled cells were found in the dentate gyrus, where they differentiated into neurons only in the intact region of the granule cell layer. Our results indicate that FGF-2 responsive progenitors can be isolated from the adult hippocampus and that these cells retain the capacity to generate mature neurons when grafted into the adult rat brain.

Utilization of three-dimensional culture for early morphometric and electrophysiological analyses of solitary cerebellar neurons

When cells from the cerebellum of late-gestation rats were grown at low density (50-100 cells/mm2) in a three-dimensional culture system, they rapidly expressed morphological and electrophysiological properties of neurons. Growth and differentiation of the population of solitary neurons as a whole was statistically assessed at 6, 12, 18, 24, 48 and 72 h using data obtained from image analysis. Mean length of axons and dendrites increased 17- and 220-fold, respectively, from 6 to 72 h. Average number of branch points rose 35-fold. Other indices of complexity increased 2- to 3-fold. Whole-cell voltage clamp revealed that as early as 24-30 h the cells displayed a tetrodotoxin-sensitive Na+ current (INa), a nifedipine-sensitive high-threshold Ca2+ current, a Ni(2+)-sensitive low-threshold Ca2+ current, and two voltage-dependent K+ outward currents consisting of a 4-aminopyridine-sensitive fast transient outward current and a CsCl-sensitive slow delayed component. These observations correlate closely with voltage-activated currents previously recorded in neonatal or young rat cerebellum, and demonstrate that the culture model is useful for analyzing the early rapid growth, differentiation and intrinsic ionic currents of these neurons as single cells.

Multiple cutaneous granular cell tumors and neurofibromatosis in childhood. A case report and review of the literature

Multiple cutaneous granular cell tumors have been previously reported in only 26 children or adolescents. An association of these tumors with neurofibromatosis has never been reported previously. We describe a 12-year-old black girl with multiple cutaneous granular cell tumors and neurofibromatosis. Although the histogenesis of these tumors is not completely clear, the findings of ultrastructural and immunohistochemical evaluation of our patient's tumors and the associated neurofibromatosis support a neural crest origin for granular cell tumors.

Solitary hypothalamic neurons inherently express vasopressin and tyrosine hydroxylase

Hypothalamic neurons were grown as single cells in three-dimensional culture. Solitary neurons lacking cell contacts were immunocytochemically examined for inherent expression of vasopressin (VP), tyrosine hydroxylase (TH), and luteinizing hormone releasing hormone (LHRH). Immunoreactive VP and TH were detected within a day. Sixty to eighty-five percent of neurons displayed homogeneously distributed reaction product for VP or TH. One percent exhibited intense punctate staining of somas and varicosities. Few neurons stained for LHRH. Results indicate that hypothalamic neurons can express appropriate neuropeptides and transmitter-specific products without contacting other neurons or nonneuronal cells. Thus, this culture system may provide a useful model to study intrinsic neuronal processes.

Stimulation of sciatic nerve regeneration in the adult rat by low-intensity electric current

Morphometric analysis was used to evaluate regeneration in transected sciatic nerves of adult rats constantly stimulated with low-intensity direct current. The ends of the cut nerve were separated by a distance of 5 mm and inserted into a Silastic tube. Histological and electron microscopy criteria were used to measure and evaluate the cross-sectional area and the structure of the bridge connecting the distal and proximal stumps. After 3 weeks of stimulation (10 microA DC with distal cathode) the stimulated animals showed a cross-sectional bridge area twice the size of nonstimulated controls. The number of myelinated and unmyelinated axons, and the vascular areas, were also larger in the experimental group. This is the first quantitative analysis of low-intensity direct current-enhanced peripheral nerve regeneration in adult mammals.

Feasibility of electrical recordings from unconnected vertebrate CNS neurons cultured in a three-dimensional extracellular matrix

Single, i.e. unconnected spinal or cerebral neurons from chick embryos rapidly regenerate morphologically identifiable axons and dendrites when cultured in a three-dimensional (3-D) extracellular matrix (ECM) consisting of a hydrated native collagen lattice. We now show that it is possible to study the intrinsic electrophysiological properties of such neurons as early as 2 days in culture. Cells were plated at 10(5) cells/dish using Medium 199 containing 10% fetal calf serum but no other supplements or antibiotics-antimycotics. A patch-clamp/whole-cell voltage clamp system was used to record single-channel currents from cell-attached patches, transmembrane potentials during the injection of rectangular currents, and whole-cell currents during voltage clamp. After 2-4 days in culture, isolated cerebral and spinal neurons exhibited single-channel currents. Within 7 days, rectangular currents injected through the recording electrode evoked action potentials. These results demonstrate that unconnected CNS neurons quickly display at least some properties of excitability when cultured in a 3-D ECM. This culture system should facilitate investigation of intrinsic electrical properties of single CNS neurons, and how extrinsic factors including neurotransmitters, hormones, pharmacological agents and contacts with other cells influence electrical activity.

Quantitation and morphological characterization of rapid axon and dendritic growth from single cerebral hemispheric neurons in hydrated collagen lattice culture

Quantitative and qualitative data are reported for single cerebral hemispheric neurons in a 3-dimensional hydrated collagen lattice (HCL) culture system. Individual neurons not in contact with other cells or cell processes, including synapses, rapidly displayed two morphologically distinct classes of processes that could be traced from origin to termination: long thin processes interpreted as being axons, and shorter tapering and sometimes branched processes interpreted as being dendrites. Axons and dendrites of single neurons that had at least one process longer than the cell body were measured on each of 3 days after plating using an image analysis system coupled to a phase-contrast microscope and a microcomputer. Mean lengths of axons and dendrites alone or combined as total new growth per neuron, increased 3- to 5-fold and were as high as 745, 694 and 1226 microns respectively after 3 days in HCL, although some individual axons measured over 1500 microns. Other indices of neuron growth and differentiation increased 1- to 5-fold including the number of primary processes, branch points, segments and growth cones. Phase-contrast microscopy, staining with Nissl and silver, and scanning and transmission electron microscopy demonstrated many single multipolar and other neurons with axons, dendrites and well-differentiated properties. The data show that individual central nervous system neurons have an inherent capacity to quickly express characteristic differentiated features and also to grow rapidly in HCL.

Ependymoneuronal specializations between LHRH fibers and cells of the cerebroventricular system

Light- and electron-microscopic immunocytochemistry (LM-ICC and EM-ICC) were used to visualize luteinizing hormone-releasing hormone (LHRH) in fibres associated with ventricular ependyma and tanycytes of the median eminence. LM-ICC suggests that LHRH fibers appear to enter the third ventricle. However, with EM-ICC, LHRH fibers are in fact found within ependymal canaliculi formed by adjacent ependymal cells. The canaliculi contain other myelinated and unmyelinated axons in addition to immunoreactive LHRH fibers. Thin slips of ependymal and tanycyte processes project into the canaliculi and enclose axons to varying degrees. At the median eminence many LHRH fibers bend sharply downwards from their ventricular course and travel with tanycytic processes towards their common destination - the perivascular space of the hypophysial-portal vascular system. Here, EM-ICC reveals that LHRH fibers closely contact basal processes of tanycytes. Lateral processes from tanycytes form glioplasmic sheaths which surround some individual LHRH fibers. A few LHRH terminals contact the perivascular space directly but more often are separated from the perivascular space by intervening glia. It is hypothesized that: (1) glia of this region responds to the physiological state of the animal and may determine the degree of LHRH secretion by varying the extent of glial investment of LHRH terminals; and (2) may play a role during development by providing direction and support for LHRH fibers similar to that described for radial and other glial cells.

The lateral antebrachial cutaneous nerve as a highly suitable autograft donor for the digital nerve

The lateral antebrachial cutaneous and digital nerves were compared by a histomorphometric method in each patient from a series of patients in whom a digital nerve was grafted with the lateral antebrachial cutaneous nerve as donor. Statistical analysis by the paired Student's test of paired data sets from all patients showed that there was no significant difference between the two nerves in regard to the following parameters: fascicular area, area of the entire nerve bundle, and percent of the nerve bundle occupied by the actual nerve fascicles. These data, together with other observations reported here, strongly support the hypothesis that the lateral antebrachial cutaneous nerve closely resembles the original fascicular pattern of the digital nerve and is, therefore, a highly suitable donor for the digital nerve.

Scanning and transmission electron microscopy of cloned rat astrocytoma cells treated with dibutyryl cyclic AMP in vitro

Two cloned rat astrocytoma cell lines, 36 B-10 and 40 A-2, maintained in vitro were treated with 1 mM dibutyryl cyclic AMP. This treatment induced arborization of cellular processes and rounding-up of cell bodies in both cell lines and was associated with increased microvillous development in 40 A-2. There were not detectable concomitant changes in either (a) the quantity or organization of microtubules or 80-100 nm microfilaments, or (b) the intensity of glial fibrillary acidic protein indirect immunofluorescence staining.

Demonstration of neurosecretory substance in previously scanned specimens: adaptation of the Gomori aldehyde-fuchsin method for correlative SEM/TEM/LM histochemistry

The Gomori aldehyde-fuchsin (AF) method for selective staining of neurosecretory substance (NSS) has been adapted to tissue previously prepared for both scanning and transmission electron microscopy (SEM/TEM). The procedure results in precise correlation of light microscopic (LM) histochemistry with SEM/TEM of the same tissue.

Scanning electron microscopy of cloned astrocytic lines derived from ethylnitrosourea-induced rat gliomas

Six cloned astrocytoma cell lines derived from four ethylnitrosourea-induced F-344 rat gliomas were viewed by scanning electron microscopy in vitro, and two were examined in vivo after transplantation to the intracerebral site. All clones consisted of stellate cells that were reasonably homogeneous within individual glioma lines. Cell membrane features common to all tumor lines included microvilli, blebs, ruffles, and miniridges, mainly confined to perikarya, and filopodia emanating chiefly from cell processes. One cell line demonstrated a profuse, and another cell line a moderate, degree of microvillous development and cell surface roughening, which in one tumor correlated with rapid in vitro cell doubling time. Both cell lines maintained these topographical appearances when transplanted into brain. These results extend the SEM observations of astrocytomas, particularly in cloned ethylnitrosourea-induced tumors in rats. The confirm that distinct variations in cell membrane topography do occur among tumors of this type, probably irrespective of their origin in humans or rats, and irrespective of their mode of genesis as spontaneous, chemically-induced, or virally-induced tumors.

The third ventricle of monkeys; Scanning electron microscopy of surface features in mature males and females

Surface features of the ependymal lining of the third ventricle in mature male and female monkeys have been investigated with scanning electron microscopy (SEM); Broad aspects of third ventricular morphology from three species of monkey are similar regardless of sex. The lateral walls are heavily ciliated whereas the ventral floor and most ventral parts of the lateral walls are not. Clumps of cilia on the lateral walls are so dense that underlying surface details are usually obscured. There is a transition zone between the ciliated lateral wall and nonciliated ventral floor. The floor and lower part of the lateral walls of the third ventricule exhibit a characteristic polygonal pattern upon which surface specializations such as microvilli, blebs and polymorphous membrane protrusions are superimposed. Ependyma of the choroid plexus of the third ventricle also display membrane specializations. Supraependymal cells are more visible in nonciliated regions.

Scanning electron microscopy of a second type of supraependymal cell in the monkey third ventricle

The third ventricle of monkeys has been examined with the scanning electron microscope (SEM). Two populations of supraependymal (SE) cells were distinguished on the basis of morphology and location. One type has been previously reported (Coates, '72, '73a,b,c). Another, type 2 SE cell, is now described. Type 2 SE cells were found in the third ventricle of both sexes and in all age groups although the numbers varied highly from animal to animal. The most common site for type 2 SE cells was the floor and transition zone of the third ventricle. Visualized with SEM, these cells had variable morphology, but may be characterized by a small cell body, few non-branching processes some of which were flared and surface features such as ruffled membranes. Type 2 SE cells most likely correspond to Kolmer or epiplexus cells originally described in association with the choroid plexus. As such, they are probably phagocytes.