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Differential sensitivity of sodium channels from the central and peripheral nervous system to the scorpion toxins Lqh-2 and Lqh-3.

The scorpion alpha-toxins Lqh-2 and Lqh-3, isolated from the venom of the Israeli yellow scorpion Leiurus quinquestriatus hebraeus, were previously shown to be very potent in removing fast inactivation of rat skeletal muscle sodium channels (Chen et al., 2000). Here, we show that tetrodotoxin-sensitive neuronal channels NaV1.2 and NaV1.7, which are mainly expressed in mammalian central and peripheral nervous systems, respectively, are differentially sensitive to these two toxins. rNaV1.2 and hNaV1.7 channels were studied with patch-clamp methods upon expression in mammalian cells. While Lqh-3 was about 100-times more potent in removing inactivation in hNaV1.7 channels compared with rNaV1.2, Lqh-2 was about 20-times more active in the other direction. Site-directed mutagenesis showed that the differences in the putative binding sites for these toxins, the S3-4 linkers of domain 4, are of major importance for Lqh-3, but not for Lqh-2.

Animals↗

Effect on the peripheral nervous system of systemically administered dimethylsulfoxide in the rat: a neurophysiological and pathological study.

The issue of dimethylsulfoxide (DMSO) neurotoxicity is an important one, given its wide use in experimental toxicology as a solvent for hydrophobic substances. We examined the effect of the intraperitoneal administration of different DMSO solutions (1.8-7. 2%) on the peripheral nervous system of Wistar rats treated for 10 consecutive days and followed-up for an additional 45 days. DMSO administration induced a dose-dependent reduction in nerve conduction velocity, with complete recovery occurring in the follow-up. No structural changes were found in the sciatic nerve at 1.8% and 3.6% DMSO concentrations, suggesting that the mechanism of action of DMSO involves a functional impairment (i.e. conduction block) similar to that already described for this substance in isolated systems. However, when DMSO was administered at the 7.2% concentration, evident structural changes were observed in the sciatic nerve, with myelin disruption and uncompacted myelin lamelle. The neurophysiological and pathological changes observed in our study are severe enough to merit careful consideration in the course of experimental studies involving DMSO as a solvent for drugs which are under evaluation for their potential neurotoxicity.

Animals↗

Induction of neuropilins-1 and -2 and their ligands, Sema3A, Sema3F, and VEGF, during Wallerian degeneration in the peripheral nervous system.

The neuropilins, NP-1 and NP-2, are coreceptors for Sema3A and Sema3F, respectively, both of which are repulsive axonal guidance molecules. NP-1 and NP-2 are also coreceptors for vascular endothelial growth factor (VEGF). The neuropilins and their ligands are known to play prominent roles in axonal pathfinding, fasciculation, and blood vessel formation during peripheral nervous system (PNS) development. We confirmed a prior report (Exp. Neurol. 172 (2001) 398) that VEGF mRNA levels rise during Wallerian degeneration in the PNS and herein demonstrate that NP-1, NP-2, Sema3A, and Sema3F mRNA levels increase in peripheral nerves distal to a transection or crush injury. In a sciatic nerve crush model, in which axonal regeneration is robust, the highest levels of Sema3F mRNA below the injury site are in the epi- and perineurium. Our results suggest the possibility that the neuropilins and their semaphorin ligands serve to guide, rather than to impede, regenerating axons in the adult PNS.

Animals↗

[Involvements of the peripheral nervous system and primary Gougerot-Sjögren syndrome].

Peripheral neuropathy in primary Sjögren's syndrome is common although often unrecognized in mild forms of this affection. They are characterized by a predominently sensory deficiency and can be divided in several entities, of which the most important are: axonal distal symmetric polyneuropathy, either of sensory or sensory-motor presentation, which are supposed to be consecutive to ischemia induced by the vasculitis of the vasa nervorum; sensory neuronopathy mimicking the paraneoplastic syndromes from a clinical and electrophysiological point of view which are supposed to be linked to neuronal degeneration secondary to a lymphocytic infiltration of the dorsal root and ganglia; trigeminal sensory neuropathy, either alone or associated with one of the previously cited forms. The prescribed courses of etiological treatment consisting of corticosteroids and immunosuppressive agents are only effective in some acute forms. Tracking down systematically these peripheral neuropathies in patients affected by Sjögren's syndrome is the best way to recognize them. Alternatively, patients with unexplained neuropathies should be evaluated for the presence of Sjögren's syndrome.

Humans↗

Peripheral nervous system lesions in experimental allergic encephalomyelitis. Ultrastructural distribution of T cells and Ia-antigen.

The distribution of T cells and Ia-antigen in peripheral nervous system (PNS) lesions of experimental allergic encephalomyelitis was studied by light- and electron-microscopic immunocytochemical techniques. Sprague Dawley rats, sensitized with guinea pig spinal cord tissue, developed a biphasic disease with acute inflammatory and chronic inflammatory demyelinating lesions in the PNS. In both the acute non-demyelinating and the chronic demyelinating disease inflammatory infiltrates were composed of T cells and Ia-positive monocytes/macrophages. Dependent upon the stage of the disease a variable percentage of T-lymphocytes carried the Ox 8 antigen (suppressor/cytotoxic cells). In demyelinating lesions no evidence for an interaction of T cells with myelin or Schwann cells was observed, thus arguing against a direct T-cell cytotoxicity in demyelination. The whole sequence of myelin destruction and digestion was performed by W3/13-, Ia+ mononuclear cells with ultrastructural features of monocytes/macrophages. In contrast to the acute inflammatory stage of the disease, high titers of anti-myelin antibodies were present in sera of affected animals sampled during the chronic inflammatory demyelinating stage. The sera from the latter animals also showed pronounced in vivo demyelinating activity when transferred into the cerebrospinal fluid (CSF) of normal recipient rats. It is thus suggested that demyelination in this model is induced by a co-operation of cell-mediated and humoral immune mechanisms. We did not find evidence for Ia-antigen expression on local elements of the PNS (Schwann cells, axons, or endothelial cells).

Animals↗

[An autosomal recessive syndrome with myopathy and central and peripheral nervous system involvement (author's transl)].

Three of 11 children, offspring of a consanguineous marriage, presented a progressive myopathy and seizures, associated with symptoms suggesting both central and peripheral nervous system involvement. The ultrastructural muscular lesions were not specific. The association of severe impairment of muscle tissue and of central nervous system is rare, being described in centronuclear myopathy, cerebromuscular dystrophy, Kearns-Sayre syndrome and in a few isolated cases. Clinically only these isolated observations and especially the Kearns-Sayre syndrome demonstrate analogies to our observations. These data lead us to the discussion of the specificity of ultrastructural lesions, especially mitochondrial abnormalities. Some authors consider these abnormalities to be the biochemical hallmark for ophthalmoplegia plus, whereas for others, especially Drachman, they are an inconstant and nonspecific finding, merely the consequence and not the cause of this disease. These observations argue for the relationship between muscular pathology and nervous system dysfunction.

Adenosine Triphosphatases↗

Herpes simplex virus types 1 and 2 in organotypic cultures of mouse central and peripheral nervous system. I. Light microscopic observations of myelin degeneration.

Mature mouse spinal cord-ganglion cultures, which contain both peripheral and central nervous system as one unit, were infected with herpes simplex virus type 1 (HSV 1) or type 2 (HSV 2) and observed by bright field microscopy for up to 72 hours. There was degeneration of both central and peripheral myelin in cultures infected with either virus, but the pattern of peripheral myelin degeneration associated with HSV 1-infected cultures was differrnt from that in HSV 2-infected cultures. Type 1 was charcterized by focal dilatations; type 2 by "sausage-shaped" swellings, and the cytopathic effect of HSV 2 both began (6 hours p.i.) and was completed (36 hours p.i.) earlier than in cultures infected with HSV 1 (12 hours and 48 hours p.i. respectively). In central nervous tissue, the apperance of degenerating myelin after infection with HSV 1 was indistinguishable from that in HSV 2-infected cultures, but the rate of myelin loss was greater in cultures infected with the type 2 virus. Evidence is presented which suggests that, at least in the peripheral nervous system,myelin degeneration did not appear to be dependent on neuronal or axonal dysfunction or death, but was a direct result of virus infection.

Animals↗

Expression of mRNAs for neurotrophic factors (NGF, BDNF, NT-3, and GDNF) and their receptors (p75NGFR, trkA, trkB, and trkC) in the adult human peripheral nervous system and nonneural tissues.

The steady-state mRNA levels of the four neurotrophic factors of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and glial cell line-derived neurotrophic factor (GDNF) and their receptors (p75NGFR, trkA, trkB and trkC) in the adult human peripheral nervous system (PNS) as well as nonneural tissues were examined using quantitative reverse transcription-polymerase chain reaction (RT-PCR). NGF and BDNF mRNA levels were high in the heart and spleen as well as in the dorsal root ganglia (DRG) and spinal cord, showing similar spatial expression patterns, while NT-3 mRNA levels were more pronounced in the liver and spleen. In contrast to these neurotrophins, GDNF mRNA expression occurred at the highest levels in the muscle, and it was also comparatively high in the spinal cord. p75NGFR mRNA was expressed extensively throughout the PNS tissues and in the spleen. The spatial expression patterns differed among trkA, and trkB and trkC mRNAs. trkA mRNA was greatly expressed in the DRG, sympathetic ganglia and spleen, while the trkB and trkC mRNA levels were high in the DRG, spinal cord and brain. The levels of trkB and trkC mRNAs with tyrosine kinase domain, compared to those with extracellular domain, were relatively high in the DRG, whereas they were low in the spinal cord and brain. The spatial patterns of the distributions of neurotrophic factors and their receptors mRNA levels in the adult human PNS and nonneural tissues are largely similar to those reported in other mammals, but these findings provide further, more specific, understanding relevant to the therapeutic approach to human diseases.

Adult↗

Familial disorder of the central and peripheral nervous systems with particular cytoplasmic lamellated inclusions in peripheral nerves, muscle satellite cells, and blood capillaries.

Four siblings of a family of 11 were afflicted with a predominant parkinsonian syndrome, pyramidal signs, intellectual deterioration, and peripheral neuropathy. Symptoms were noticed first when they were aged 8 years; the condition was slowly progressive. All presented similar clinical features of varying severity. Nerve and muscle biopsies of two patients exhibited inclusions of concentric lamellae 2 nm thick with a periodicity of 3.6 nm, in the cytoplasm of perineurial and Schwann cells, endothelial cells and pericytes of blood capillaries, and muscle satellite cells. These inclusions differ in their location and morphological features from other inclusions that have been described in nerve and muscle biopsies of many disorders. The features of these inclusions suggest that they may represent a storage deposit whose nature could not be determined. They may be a distinguishing morphological feature of a multisystem disorder which to our knowledge has not been identified previously.

Adult↗

The myelin proteins of the shark brain are similar to the myelin proteins of the mammalian peripheral nervous system.

The two major structural proteins in the shark CNS are similar to the structural proteins, Po and myelin basic protein (MBP), found in the mammalian peripheral nervous system (PNS). Shark Po is 46% similar to its mammalian counterpart. The extracellular domain of shark Po also appears to be organized as an immunoglobulin-like domain that mediates homotypic interactions. The intracellular domain of shark Po also is very basic and may play a role in myelin condensation analogous to that of MBP. Shark MBP is 44% similar to mammalian MBP. Both MBPs show conserved interspersed regions and are present in multiple forms that arise by alternative splicing of a single transcript. These structural analyses indicate that the complexities seen in mammalian myelin arose early during vertebrate evolution.

Amino Acid Sequence↗

Effect of gamma-interferon on the expression of major histocompatibility complex class I and II gene products in neural cells isolated from the developing human fetal peripheral nervous system.

The effect of gamma-interferon (gamma-IFN) on the expression of major histocompatibility complex (MHC) gene products was examined in the developing human fetal peripheral nervous system. RNA blot hybridization analysis of total RNA isolated from human fetal dorsal root ganglia (DRG) neural cell populations cultured in vitro for 5 days resulted in the detection of both MHC class I- and class II-specific RNAs. As determined by protein immunoblotting and fluorescence-activated flow cytometry, MHC class I and II proteins were also readily detectable in cultured human fetal DRG neural cell populations 5 days after isolation. In addition, treatment of 3-day human fetal DRG neural cells with gamma-IFN (100 U/ml; 48 h) resulted in a marked increase in the level of MHC class I- and class II-specific RNA and protein without inhibiting the proliferation of the neural cell population. These results suggest that changes in the levels of selected cytokines such as gamma-IFN may alter the ability of specific neural cell populations present in the developing human nervous system to participate in immune reactions by alteration of MHC class I and II antigen expression which may lead to perturbation in glial cell function and ultimately to nervous system dysfunction in general.

Cell Division↗

Amphibian sympathetic ganglia as a model system for investigating regeneration in the vertebrate peripheral nervous system.

1. The paravertebral sympathetic ganglion of the bullfrog serves as an excellent experimental system in which to study the response of vertebrate neurones to axotomy and the mechanisms associated with regeneration. 2. Various types of lesions to the axons (axotomy) of these neurones promote distinct and reproducible changes in the electrophysiological properties of the cell bodies which are not a consequence of changes in cell body morphology. 3. The axotomy-induced increase in spike width and decrease in the amplitude of the action potential after-hyperpolarization may allow an increase in Ca2+ influx and thereby promote regrowth. 4. The axotomy-induced decrease in after-hyperpolarization duration may reflect the disconnection of the neurone with its target and the loss of available nerve growth factor (NGF) from the target. 5. Experiments with NGF antibodies provide evidence that an NGF-like substances serves to maintain the normal electrophysiological characteristics of amphibian sympathetic neurones.

Amphibians↗

Transforming growth factor beta isoforms in the adult rat central and peripheral nervous system.

The distribution of transforming growth factor-beta isoforms 1, 2 and 3 and transforming growth factor-beta 2 and 3 mRNAs in adult rat central and peripheral nervous system was examined using Northern blotting and isoform specific antibodies for immunocytochemistry. Transforming growth factor-beta 2 and 3 mRNA were present in all brain areas including cerebral cortex, hippocampus, striatum, cerebellum and brainstem. In sciatic nerve, transforming growth factor-beta 3 mRNA was highly expressed, but transforming growth factor-beta 2 mRNA was not detectable. Transforming growth factor-beta 1-like immunoreactivity was confined to meninges and choroid plexus in the brain and connective tissue in peripheral ganglia and nerves. Transforming growth factor-beta 2 and 3 immunoreactivity entirely overlapped and, in general, were found in large multipolar neurons. Highest densities of immunoreactive neuronal perikarya were present in spinal cord and brainstem motor nuclei, hypothalamus, amygdaloid complex, hippocampus and cerebral cortical layers II, III and V. Most thalamic nuclei, superior colliculi, periaqueductal gray and striatum were almost devoid of transforming growth factor-beta 2- and 3-immunoreactive neurons. Fibrous astrocytes in white matter areas were intensely immunostained. Most dorsal root ganglionic neurons, their satellite cells and Schwann cells in peripheral nerves were also labeled. Transforming growth factor-beta 2- and 3-immunoreactive neurons were localized in brain regions that have been shown to contain neurons synthesizing and/or storing basic fibroblast growth factor suggesting possible opposing or synergistic effects of these peptide growth factors. However, the precise functions of local synthesis and storage of the transforming growth factor-beta isoforms in the nervous system are as yet unknown.

Animals↗

[Evaluation of the peripheral nervous system by studying the F wave in patients with lung and brain tumors].

In 50 patients with various tumours: 25 with pulmonary cancer and 25 with brain tumours, the peripheral nervous system was studied carefully, both clinically and electrophysiologically, with evaluation of orthodromic conduction in motor fibres and F wave. Evidence of peripheral nerve damage was found by physical examination in 4% of pulmonary cancer cases and in 8% of these cases by analysis of orthodromic motor nerve conduction and in about 16% of cases by the method of F wave conduction. The size of the deviations was significantly greater also in the F wave responses. In patients with brain tumours no significant abnormalities were found in nerve conduction.

Adolescent↗

Gender-specific polygenic control of ethylnitrosourea-induced oncogenesis in the rat peripheral nervous system.

The inbred BD rat strains constitute a model system for analysis of the genetic basis of susceptibility or resistance to the development of neural tumors, as they exhibit distinct strain-specific differences regarding the sensitivity to tumor induction by the alkylating carcinogen N-ethyl-N-nitrosourea (EtNU). Among the different BD strains, BDIX and BDIV rats, respectively, are either highly susceptible or entirely resistant to the development of EtNU-induced malignant schwannomas of the peripheral nervous system (PNS), predominantly of the trigeminal nerves. We have previously mapped one locus associated with susceptibility/resistance to schwannoma induction to the telomeric third of chromosome 10 (Mss1) in segregating (BDIX x BDIV) crosses. We report on the genetic mapping of 6 further loci controlling tumor incidence or survival time on chromosomes 1 (Mss2), 3 (Mss3), 6 (Mss4), 13 (Mss5) and 15 (Mss6) as well as on chromosome 10 (Mss7) close to the centromere. Interestingly, most of these loci mediate gender-specific effects of variable strength ranging from minor influences on tumor development to complete tumor resistance. The gender specificity is reflected by the fact that male (BDIX x BDIV) F2 rats exhibit a 2-fold higher incidence of EtNU-induced schwannomas than females as well as a shorter survival time. A number of human nervous system tumors too arise with a marked gender bias. Genes mediating gender-specific predisposition of developing malignant schwannomas in the rat may be relevant for the human individual risk of developing nervous system tumors.

Alkylating Agents↗

Cytochemical demonstration of TPPase in myelinated fibers in the central and peripheral nervous system of the rat.

Thiamine pyrophosphatase (TPPase) activity was demonstrated by means of cytochemistry and electron microscopy in association with myelinated fibers in the central and peripheral nervous system of the rat. The areas studied included corpus callosum, hippocampus, cerebral cortex, cervical spinal cord and sciatic nerves. In the myelin sheaths, the enzymatic activity was found in 3 locations: (1) within oligodendroglial and Schwann cytoplasmic clefts between myelin lamellae; (2) in the major dense line of myelin; and (3) within the periaxonal space. In addition to this myelin-associated TPPase, enzymatic activity was also observed in specific cytoplasmic localizations in myelinogenic cells. Oligodendrocytes displayed TPPase activity within the nuclear envelope and the endoplasmic reticulum cisternae, whereas Schwann cells displayed TPPase activity within the endoplasmic reticulum and Golgi saccules. The results are discussed in relation to the role that TPPase might play in myelinated fibers, including roles in the conduction of nerve impulses or roles in the maintenance of structural configuration of myelin sheaths.

Animals↗

Gene delivery to the central and peripheral nervous systems of mice using HSV1 ICP34.5 deletion mutant vectors.

Herpes simplex virus 1 (HSV1) ICP34.5 deletion mutants are avirulent upon inoculation of both the central and peripheral nervous systems of mice, but they replicate to near wild-type titres in a number of non-neuronally derived cell lines in culture. Thus these mutants might be suitable for development as safe vectors for gene transfer to the nervous system. However, the mechanism of this avirulent phenotype in neuronal cells is at present poorly understood, although it has been suggested that nonpermissive cells infected with these mutants may undergo apoptosis, the function of ICP34.5 being to prevent this response and to allow continued virus replication. If this were the case ICP34.5 null mutants might be unsuitable for gene transfer as infected cells would quickly die, limiting the expression of a transgene. Here we have inserted a beta-galactosidase marker gene into a nonessential gene of an HSV1 strain 17+ mutant in which ICP34.5 has been deleted and also into a second mutant in which the virion transactivator protein VMW65 is also inactive. While all the mutants grew to high titre in tissue culture, mice inoculated by the foot-pad or intracranial route at high titre remained healthy until the end of the experiment. Moreover, beta-galactosidase was expressed either in the brain or in the dorsal root ganglia, depending on the site of inoculation. This suggests that in vivo the absence of ICP34.5 does not prevent the expression of a transgene in neuronal tissue and indicates that non-neurovirulent mutants lacking this gene may be suitable for further development as safe vectors for gene therapy in vivo.

Animals↗