NPY样免疫反应在蝾螈发育过程中神经系统的定位研究

By immuno-cytochemical method the localization of neuropeptide Y (NPY) in the nervous system during embryonic development of Cynops orientalis was studied. The results revealed that NPY was first localized in the peripheral nervous system (late tail-bud stage), and later appeared in the central nervous system (larval stage) where it appeared with the appearance of glial cells. Very probably with the migration of neural crest cells NPY appeared first in the peripheral nervous system and then distributed to the central nervous system.     

NPY样免疫反应在蝾螈发育过程中神经系统的定位研究

用免疫组化方法研究在蝾螈胚胎发育中神经肽Y(NPY)在神经系统中的定位.结果表明NPY最早分布在周边神经系统(尾芽晚期),之后才在中枢神经系统出现(幼虫期),而且是随着胶质细胞的出现而出现的.我们认为NPY是随着神经嵴细胞的迁移而进入周边神经系统,再分布到中枢神经系统的.     

Nervous system development of the sea cucumber Stichopus japonicus

The nervous system development of the sea cucumber Stichopus japonicus was investigated to explore the development of the bilateral larval nervous system into the pentaradial adult form typical of echinoderms. The first nerve cells were detected in the apical region of epidermis in the late gastrula. In the auricularia larvae, nerve tracts were seen along the ciliary band. There was a pair of bilateral apical ganglia consisted of serotonergic nerve cells lined along the ciliary bands. During the transition to the doliolaria larvae, the nerve tracts rearranged together with the ciliary bands, but they were not segmented and remained continuous. The doliolaria larvae possessed nerves along the ciliary rings but strongly retained the features of auricularia larvae nerve pattern. The adult nervous system began to develop inside the doliolaria larvae before the larval nervous system disappears. None of the larval nervous system was observed to be incorporated into the adult nervous system with immunohistochemistry. Since S. japonicus are known to possess an ancestral mode of development for echinoderms, these results suggest that the larval nervous system and the adult nervous system were probably formed independently in the last common ancestor of echinoderms.     

Mechanisms of glial development

Glial cells comprise most of the non-neuronal cells of the brain and peripheral nervous system, and include the myelin-forming oligodendrocytes and Schwann cells, radial glia and astrocytes. Their functions are diverse and include almost every aspect of nervous system function, from the birth and death of cells to the migrations and cell-cell interactions that connect and integrate the working elements of the nervous system. Recent studies have provided exciting insights into the mechanisms that drive the conversion into a glial cell and the developmental signals that guide the behavior of these multifunctional cells. An emerging theme is the so-called glial lineage being more diverse and more plastic than was previously thought. Here, we highlight some recent insights into glial development.     

Microscopic anatomy and ultrastructure of the nervous system of <Emphasis Type="Italic">Phoronopsis harmeri</Emphasis> Pixell, 1912 (Lophophorata: Phoronida)

The microscopic anatomy and ultrastructure of the nervous system of Phoronopsis harmeri was investigated using histological techniques and electron microscopy. The collar nerve ring is basically formed by circular nerve fibers originating from sensitive cells of tentacles. The dorsal nerve plexus principally consists of large motor neurons. It is shown for the first time that the sensitive collar nerve ring immediately passes into the motor dorsal nerve plexus. The basic components of the nervous system have similar cytoarchitectonics and a layered structure. The first layer is formed by numerous nerve fibers surrounded by the processes of glia-like cells. The bodies of glia-like cells constitute the second layer. The third layer consists of neuron bodies overarched by the bodies of epidermal cells. The giant nervous fiber is accompanied by more than one hundred nerve fibers of a common structure and, thus, marks the true longitudinal nerve. The phoronids possess one or two longitudinal nerves. It is supposed that the plexus nature of the nervous system in phoronids may be related to their phylogenesis. A comparison of the nervous system organization and body plans among the Lophophorata suggests that the nervous system of phoronids cannot be considered as a reductive variant of the brachiopod nervous system. At the same time, the structure of the nervous system of bryozoans can be derived from that of phoronids.     

Role of gangliosides in the processes of calcium ion transport across the membranes of nerve cells

It has been demonstrated that the content of extracellular Ca in the nervous system is inversely related to the content of gangliosides. The results obtained on invertebrates, lower and higher vertebrates indicate that the highest content of extracellular Ca is typical of the nervous tissue of invertebrates, whereas the lower one--of the nervous tissue of higher vertebrates (mammals). Ganglioside content, on the contrary, is the highest in the brain tissue of the higher vertebrates (mammals and birds), being significantly lower in lower vertebrates; no gangliosides was found at all in the nervous tissue of protostomian invertebrates. The highest ganglioside content in the organism of vertebrates is characteristic to the surface membranes of the nervous cells, especially in the region of synapses. Functional significance of the inverse relationship between the content of extracellular Ca and gangliosides is discussed from the standpoint of one of the authors (R. Veh) who postulated the existence of calcium--ganglioside buffer in the vicinity of the surface of the nervous cells.     

Lipopolysaccharide-evoked activation of p38 and JNK leads to an increase in ICAM-1 expression in Schwann cells of sciatic nerves

Lipopolysaccharide is a major constituent of the outer membrane of Gram-negative bacteria. It activates monocytes and macrophages to produce cytokines such as tumor necrosis factor-alpha and interleukins IL-1beta and IL-6. These cytokines appear to be responsible for the neurotoxicity observed in peripheral nervous system inflammatory disease. It has been reported that, in the central nervous system, the expression level of intercellular adhesion molecule-1 (ICAM-1) was dramatically upregulated in response to LPS, as well as many inflammatory cytokines. ICAM-1 contributes to multiple processes seen in central nervous system inflammatory disease, for example migration of leukocytes to inflammatory sites, and adhesion of polymorphonuclear cells and monocytes to central nervous system cells. In the present study, we found that lipopolysacharide evoked ICAM-1 mRNA and protein expression early at 1 h post-injection, and the most significant increase was seen at 4 h. Immunofluorescence double-labeling suggested that most of the ICAM-1-positive staining was located in Schwann cells. Using Schwann cell cultures, we demonstrated that ICAM-1 expression in Schwann cells is regulated by mitogen-activated protein kinases, especially the p38 and stress-activated protein kinase/c-Jun N-terminal kinase pathways. Thus, it is thought that upregulation of ICAM-1 expression in Schwann cells may be important for host defenses after peripheral nervous system injury, and reducing the biosynthesis of ICAM-1 and other cytokines by blocking the cell signal pathway might provide a new strategy against inflammatory and immune reaction after peripheral nerve injury.     

The role of mast cells in virus-induced inflammation in the murine central nervous system

The mononuclear inflammatory response to Sindbis virus infection of the central nervous system is analogous to the cutaneous delayed-type hypersensitivity reaction. It is dependent on sensitized T cells for initiation, but many of the cells present are nonsensitized bone marrow-derived cells. Tissue mast cells have been shown to be important for the development of the delayed-type hypersensitivity reaction in the skin where capillary endothelial cells are joined by tight junctions. To determine whether mast cells are also important for the development of an immune-mediated inflammatory response across the endothelial tight junctions of the blood-brain barrier, the development of mononuclear inflammation in the central nervous system of reserpine-treated mice and mast cell-deficient mice (WBB6F1-W/Wv) was studied after infection with Sindbis virus. Three central nervous system compartments, the cerebrospinal fluid, the meninges, and the brain parenchyma, were evaluated for inflammation by counting the number of cells present, by grading the histopathologic lesions, and by labeling infiltrating cells with 125IUDR. By all parameters inflammation was reduced when mice were treated with reserpine or were deficient in mast cells. Antigen-specific humoral and cellular immune responses were depressed and virus clearance delayed in reserpine-treated mice, but not in mast cell deficient mice. It is concluded that the vasoactive amines released by mast cells in the central nervous system play a facilitating role in the development of the inflammatory response to Sindbis virus.     

Distribution of PACAP-like immunoreactivity in the nervous system of oligochaeta

The marked similarity between the primary structures of human, other vertebrate, and the invertebrate tunicate PACAP suggests that PACAP is one of the most highly conserved peptides during the phylogeny of the metazoans. We investigated the distribution of PACAP-like immunoreactivity in the nervous system of three oligochaete (Annelida) worms with immunocytochemistry. The distribution pattern of immunoreactivity was similar in all three species (Lumbricus terrestris, Eisenia fetida, and Lumbricus polyphemus). The cerebral ganglion contains numerous immunoreactive cells and fibers. A few cells and fibers were found in the medial and lateral parts of the subesophageal and ventral cord ganglia. In the peripheral nervous system, immunoreactivity was found in the enteric nervous system, in epidermal sensory cells, and in the clitellum.     

Localization of immunoreactive epidermal growth factor receptors in human nervous system

Epidermal growth factor is a well-defined peptide which stimulates cell growth and elicits cell responses in a variety of tissues by binding to specific receptors, EGF-R. A specific antiserum against the EGF receptor, which has previously been used to characterize EGF-R in human skin, fibroblasts, and smooth muscle, was used to survey the distribution of EGF-R in human nervous system. Portions of formalin-fixed, paraffin-embedded autopsy specimens were examined by use of immunohistochemical staining (PAP technique) with EGF-R antiserum. Many types of nerve cells, e.g., cerebral cortical pyramidal cells, hippocampal pyramidal cells, Purkinje cells, anterior horn cells, and dorsal root ganglion neurons, contained immunoreactive EGF-R. However, immunoreactive EGF-R were not detected in astrocytes, oligodendrogliocytes, and other small neurons such as granule cells. Intense immunostaining for EGF-R was also detected in ependymal cells from choroidal and extrachoroidal locations. Although immunoreactive EGF-R is widely distributed in human nervous system, the functional role of EGF and its receptor in the nervous system remains unknown.     

Electron microscopic-cytochemical study of succinate dehydrogenase activity of nerve tissue cells of human embryos in vitro

The ultrastructural localization of succinate dehydrogenase (SDH) activity was revealed in astrocyte-like cells of 26 days old nervous tissue organotypic cultures. The Kerpel-Fronius and Hajos (1968) technique was employed using potassium ferricyanide as an artificial acceptor of electrons. The localization of the reaction product was seen more often in cells with long, thread-like mitochondria. The appearance of such organelles with a large membrane length and high enzymatic activity is suggested to reflect one of the mechanisms of adaptation of nervous tissue cells providing the adequate level of the energy supply under in vitro conditions.     

T-cell-mediated clearance of mouse hepatitis virus strain JHM from the central nervous system

Clearance of the neurotropic JHM strain of mouse hepatitis virus from the central nervous system was examined by the transfer of spleen cells from immunized donors. A T cell with the surface phenotype of Thy1.2+ CD4+ CD8- asialo-GM1+ Mac-1- was found to be necessary for viral clearance. The surface phenotype and adherence to nylon wool suggest that these cells are activated helper-inducer T cells. Adoptive transfer to congenic histocompatibility strains demonstrated the necessity for compatibility at the D locus of the major histocompatibility complex. The expression of the CD4 surface marker and the requirement for major histocompatibility complex class I were further studied by the transfer of cells to recipients treated with anti-CD4 or anti-CD8 monoclonal antibodies. Treatment of recipients with either the anti-CD8 or the anti-CD4 antibodies inhibited virus clearance from the central nervous system. This suggests that the CD4+ cell acts as a helper and that virus is cleared from the central nervous system. This suggests that the CD4+ cell acts as a helper and that virus is cleared from the central nervous system by CD8+ cells that recognize viral antigen in the context of the H-2Db gene product.     

Base composition, selection, and phylogenetic significance of indels in the recombination activating gene-1 in vertebrates

Background

Echinoderms and chordates belong to the same monophyletic taxon, the Deuterostomia. In spite of significant differences in body plan organization, the two phyla may share more common traits than was thought previously. Of particular interest are the common features in the organization of the central nervous system. The present study employs two polyclonal antisera raised against bovine Reissner's substance (RS), a secretory product produced by glial cells of the subcomissural organ, to study RS-like immunoreactivity in the central nervous system of sea cucumbers.

Results

In the ectoneural division of the nervous system, both antisera recognize the content of secretory vacuoles in the apical cytoplasm of the radial glia-like cells of the neuroepithelium and in the flattened glial cells of the non-neural epineural roof epithelium. The secreted immunopositive material seems to form a thin layer covering the cell apices. There is no accumulation of the immunoreactive material on the apical surface of the hyponeural neuroepithelium or the hyponeural roof epithelium. Besides labelling the supporting cells and flattened glial cells of the epineural roof epithelium, both anti-RS antisera reveal a previously unknown putative glial cell type within the neural parenchyma of the holothurian nervous system.

Conclusion

Our results show that: a) the glial cells of the holothurian tubular nervous system produce a material similar to Reissner's substance known to be synthesized by secretory glial cells in all chordates studied so far; b) the nervous system of sea cucumbers shows a previously unrealized complexity of glial organization. Our findings also provide significant clues for interpretation of the evolution of the nervous system in the Deuterostomia. It is suggested that echinoderms and chordates might have inherited the RS-producing radial glial cell type from the central nervous system of their common ancestor, i.e., the last common ancestor of all the Deuterostomia.     

Development of the enteric nervous system in chick embryonic duodenum in terms of the distribution of tubulin

An immunohistochemical method that uses anti-tubulin was utilized to observe the development of the enteric nervous system in chick embryonic duodenum. Neural crest cells, and enteric neuroblasts, or enteric ganglia, which derive from neural crest cells were clearly shown as sharp immunoreactive regions of tubulin. The distributions of enteric neuroblasts and enteric ganglia in chick duodena were in agreement with results of previous reports in which different techniques were used. The initial stage at which cells of neural crest origin were present in the duodenal walls (4-day-old embryos) was earlier than the initial stage (about 6-day-old embryos) reported earlier. This was verified by transmission electron microscopy. Also, the tubulin that is a component of the enteric nervous system was shown to be stable at a low temperature. This tubulin-immunostaining method provides a useful histochemical technique with which to study the development of the enteric ganglion and the function of tubulin as a component of the enteric nervous system.     

Control of peripheral glial cell proliferation: a comparison of the division rates of enteric glia and Schwann cells and their response to mitogens

The enteric nervous system comprises neurons and a relatively homogeneous population of glial cells, which differ considerably from those found in other parts of the peripheral nervous system and resemble more closely astrocytes from the central nervous system. It provides a simple model system for the study of neuron/glial interactions and glial cell development. In this study the proliferation rates of purified populations of enteric glia and Schwann cells and their response to several mitogens in vitro were compared. Enteric glial cells divided at a much higher rate than Schwann cells in both serum-containing and serum-free media. This difference in their basal proliferation rates was the major difference seen between the two cell types. Both cell populations were stimulated to divide by fibroblast growth factor and glial growth factor but not by epidermal growth factor. Enteric glial cells and Schwann cells proliferated at a greater rate on a basement membrane-like extracellular matrix produced by corneal endothelial cells, laminin, and fibronectin than on poly-L-lysine-coated glass coverslips. The magnitude of stimulation was greater for Schwann cells, presumably due to their lower basal division rates. Like Schwann cells, enteric glial cells were stimulated to divide by two agents which elevate intracellular cAMP, cholera toxin, and dibutyryl cAMP.     

Intramural ganglia of the human gallbladder: morphological and functional observations]

The purpose of this study was the reinvestigation of the intrinsic innervation of human gall bladder with an immunohistochemical technique named peroxidase anti-peroxidase (PAP). The antigen demonstrated was the S100 protein normally present in the surface of glial cells, Schwann cells and satellite cells in ganglia. The tissues used were taken from 20 human gall bladders, fixed after surgery. This technique is not specific to demonstrate adrenergic or cholinergic innervation but it reveals just myelinated fibers. The current study was undertaken in order to study the organization and the function of plexus of nerves and ganglia present in the wall of the gall bladder. The neck of the gall bladder was the region in which the higher number of nerve cells and nervous fibers was present. The technique used has demonstrated ganglionated plexus and nerves in submucosal layer, fibromuscular and adventitial layer according to the enteric nervous system. All ganglia are postganglionic stations related with preganglionic cholinergic fibers. These results confirm that the intramural ganglia of the gall bladder are analogous to those of the enteric nervous system according to their common origin.     

Identification of the Schwann cell as a peripheral nervous system cell possessing a differentiation antigen expressed by a human lung tumor.

Recent studies of the plasma membrane antigens of a human lung tumor (oat cell carcinoma) indicated that the tumor expressed at least two normal differentiation antigens undetectable in normal respiratory epithelium. One antigen was characteristic of certain endodermally derived epithelial cells of the digestive system; the other antigen was characteristic of certain neural crest-derived cells in the peripheral nervous system. The present studies were undertaken to identify the reactive cell type in the peripheral nervous system. Since similar cells in the rat peripheral nervous system expressed a cross-reactive form of this antigen, and since pure cultures of different rat nerve cell type were available, the following approach was possible. Cultures of pure neurons, pure Schwann cells, pure fibroblasts, neurons and Schwann cells, and neurons, Schwann cells, and fibroblasts were assayed for this antigen with rabbit anti-oat cell carcinoma plasma membrane antiserum absorbed with normal lung and liver. The indirect immunofluorescence method on both whole, viable cell and fixed cell substrates was used. Only Schwann cells expressed the antigen; Schwann cells in the presence of neurons expressed the antigen much more strongly than did pure Schwann cells. It was concluded that the oat cell carcinoma of the lung expressed a differentiation antigen present on Schwann cells.     

Glial cells

The nervous system is built from two broad categories of cells, neurones and glial cells. The glial cells outnumber the neurones and the two cell types occupy a comparable amount of space in nervous tissue. The main glial cell types are, in the central nervous system, astrocytes and oligodendrocytes and, in the peripheral nervous system, Schwann cells, enteric glial cells and satellite cells. In the embryo, glial cells form a cellular framework that permits the development of the rest of the nervous system, and regulate neuronal survival and differentiation. The best known function of glia in the adult is the formation of myelin sheaths around axons thus allowing the fast conduction of signalling essential for nervous system function. Glia also maintain appropriate concentrations of ions and neurotransmitters in the neuronal environment. Increasing body of evidence indicates that glial cells are essential regulators of the formation, maintenance and function of synapses, the key functional unit of the nervous system.