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NSPc1, a novel mammalian Polycomb gene, is expressed in neural crest-derived structures of the peripheral nervous system.

Anterior-posterior (A-P) patterning is a key element in early embryonic development. Polycomb group (PcG) genes act as transcriptional repressors to regulate A-P patterning by either directly or indirectly controlling the coordinated expression of the HOM/Hox homeobox (Curr. Opin. Genet. Dev. 7 (1997) 488; Trends Genet. 13 (1997) 167). We describe the isolation and characterization of a novel mammalian PcG gene, termed Nervous System Polycomb-1 (NSPc1). Human and mouse NSPc1 genes encode proteins with an N-terminal RING finger domain and share homology with Drosophila melanogaster lethal(3)73Ah and the mammalian Mel18 and Bmi1 genes. Transcripts are observed at 10 dpc in the otic vesicle, urogenital bud and dorsal root ganglia. At 11.5 dpc, transcripts are present in a subset of neural crest cell derivatives of the peripheral nervous system, and in the neural tube. NSPc1 expression is ubiquitous in adult tissue.

Amino Acid Sequence↗

Neuronotoxicity of axonally transported toxic lectins, abrin, modeccin and volkensin in rat peripheral nervous system.

In an attempt to find new and more useful suicide transport agents, the cytotoxic lectins abrin, modeccin and volkensin were pressure microinjected into peripheral nerves (vagus, hypoglossal and sciatic) of adult rats. After 33 h-5 days survival, the brainstems, spinal cords and corresponding sensory ganglia were examined histologically. All three lectins produced profound chromatolysis, and destruction of sensory and motor neurons projecting axons through the injected nerves. Volkensin and modeccin were significantly more potent than any previously reported suicide transport agent. It is concluded that abrin, modeccin and volkensin are effective, unselective suicide transport agents in the rat peripheral nervous system but none is clearly superior to ricin for making restricted sensory and motor neuron ablations. However, modeccin and volkensin are fundamentally different from any previously reported suicide transport agents with respect to spread within the CNS which destroyed neurons adjacent to those initially taking up and transporting the toxin. Possibly this is due to the different oligosaccharide binding specificity of modeccin and volkensin compared to other suicide transport agents. Modeccin and/or volkensin may prove useful in making lesions of CNS interneurons using the suicide transport strategy.

Abrin↗

[High molecular weight tau proteins and acquisition of neuronal polarity in peripheral nervous system].

Several variants of the microtubule-associated tau proteins, are expressed during brain development and in adulthood. These entities are required to define the polarity of the neuron and the architecture of the axon but differ in sequence and in their microtubule polymerizing activity. Here, we describe a new group of high molecular weight tau proteins that contain one or two additional exons of 711 and 198 bp in their middle region and a variable N-terminal domain. These high molecular weight tau variants are preferentially expressed in the peripheral nervous system. Immunohistochemical studies showed that they are also present in the dorsal horn of the spinal cord where they are probably transported by sensory fibers arising in the periphery. However, a minor fraction of these proteins is present in the motor neurons of the ventral horn. Similar studies were performed with the neuroblastoma N115 cell line which can be differentiated in vitro and expresses only high molecular weight tau forms. In the non differentiated cells, tau antibodies label the domain of the cell body localized around the centrosome whereas, after differentiation, the cell process facing this structure is also stained. These data suggest that axonal polarity is predetermined by the localization of tau proteins in the domain of the cell body defined by the centrosome.

Animals↗

[Importance of a screening system in the prevention of diseases of the lumbosacral division of the peripheral nervous system].

An automated screening system for prophylactic examinations is offered. The system enables one to reveal early compensated forms of lumbar osteochondrosis, as well as persons with an increased risk of that disease. The system is based on a statistical analysis of the lumbar osteochondrosis risk factors revealed in a particular individual, and involves the use of a computer. The practical use of this system at large industrial plants has made it possible to reveal potential patients to whom individual therapeutic and prophylactic complexes were administered. It is shown that the size of the risk groups in workshops depends on the character of the production operations performed and on the working conditions, the correlates with the prevalence of the disease in each particular collective body.

Automobiles↗

Actions of steroid hormones- and growth factors on glial cells of the central and peripheral nervous system.

Primary cultures of oligodendrocytes and astrocytes and purified cultures of Schwann cells were prepared respectively from forebrain and sciatic nerves of newborn rats. The effects of steroid hormones and growth factors on glial cell growth and on the production of myelin-specific proteins and lipids were investigated. Progesterone (P, 100 nM) decreased the proliferation of glial cells of the central nervous system. This inhibitory effect of P was abolished by the simultaneous administration of the antagonist RU486, thus suggesting a receptor-mediated action of the hormone. The expression of myelin-specific proteins, including the myelin basic protein (MBP) and the 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNPase), and of a myelin-specific lipid, galactocerebroside (Gal C), was also measured during cell differentiation under different hormonal conditions. The expression of MBP in oligodendrocytes was increased by P, and this effect was not blocked by RU486. The combined application of P and insulin promoted a synergistic stimulation of MBP expression. Insulin, by itself, also increased the number of MBP-positive oligodendrocytes in culture. The effects of P and insulin appeared to be selective as dexamethasone, dehydroepiandrosterone, pregnanolone and epidermal growth factor (EGF) had no effect. Only estradiol (E2, 500 nM) increased the number of MBP-immunoreactive cells, but in contrast to P, only a small synergism between E2 and insulin on MBP expression was observed. The expression of CNPase, another myelin-specific protein, was also increased by P and, here again, a synergy between P and insulin could be observed. In contrast, the expression of Gal C, a myelin-specific lipid, was not modified by P or other steroid hormones. Moreover, the increase in Gal C-positive cells observed in response to insulin alone was not further potentiated by P. Glial cells of the peripheral nervous system, namely Schwann cells, are also sensitive to steroid hormones. Schwann cells contain estrogen receptors, and E2 stimulates their proliferation in the presence of forskolin or dibutyryl cyclic AMP (dbcAMP). The mitogenic effect of E2 was abolished by the pure antiestrogen ICI-164,384. Insulin, at micromolar concentration, also stimulated Schwann cell growth when forskolin or dbcAMP were present in the culture medium. The mitogenic effect of insulin was mediated by insulin-like growth factor I (IGF-I) receptors. Indeed, at a physiological nanomolar concentration, IGF-I but not insulin or IGF-II, increased the proliferation of Schwann cells in synergy with forskolin. In addition, Schwann cells express receptors for IGF-I.

Animals↗

Adenoviral gene transfer in the peripheral nervous system.

BACKGROUND: Viral vectors have gained widespread use as vehicles for somatic gene transfer, and the targeted expression of foreign proteins by these vectors offers advantages over the systemic administration of the drugs in some therapeutic situations. Selective virus-mediated gene transfer to the peripheral nervous system (PNS), however, remains to be established. There are no data showing efficiency of protein transduction in the PNS, which consists of a variety of cell types, many of which are postmitotic. METHODS: We prepared the first-generation replication-deficient recombinant adenovirus vectors engineered to express LacZ. Eight-week-old Wister rats were used in this study. Adenovirus vector (5 microl) containing the LacZ gene (5 x 10(8) pfu) was injected into rat sciatic nerves or the dorsal root ganglia at the level of L5. The sciatic nerves, the dorsal root ganglia, and the spinal cords were obtained 7, 14, 21, and 28 days after injection. Expression of LacZ was assessed by X-gal histochemistry and beta-gal immunohistochemistry. RESULTS: Following injection of the adenovirus carrying the LacZ gene into the sciatic nerve, LacZ expression was seen mainly in the Schwann cells and the small neurons in the dorsal root ganglion. In contrast, expression was observed in the primary nerve terminals of the spinal dorsal horn and the small to large dorsal root ganglion neurons and the Schwann cells after injection of the vectors into the L5 dorsal root ganglion. There were no side effects in rats with injection in the dorsal root ganglia or the sciatic nerve. CONCLUSIONS: The present study shows efficient protein transduction by adenovirus vectors in the PNS. It is noted that injection of the virus into the dorsal root ganglia leads to extensive expression of LacZ in the spinal cord, the dorsal root ganglia, and the sciatic nerves.

Adenoviridae↗

Nitric oxide synthase in the peripheral nervous system of the goldfish, Carassius auratus.

Neuronal nitric oxide synthase was located in various organs of the goldfish by NADPH-diaphorase histochemistry and immunohistochemistry. Positive cells were detected throughout the digestive tract. A particularly dense plexus of nitric-oxide-synthase-containing fibers was present at the opening of the pneumatic duct into the esophagus and at the intestinal sphincter separating the esophagus and the intestinal bulb. The nitroxergic innervation was mainly confined to the muscularis. The muscular layer of the swim bladder and of the pneumatic duct was densely equipped with stained neurons and fibers. In the heart, the majority of small neurons located at the sinu-atrial junction was found to be positive for nitric oxide synthase. The muscularis of the urinary duct was supplied by fibers originating from many intramural ganglia harboring intensely stained neurons. These results suggest that nitric oxide represents a widespread transmitter in the peripheral nervous system of teleost species.

Animals↗

Immunolocalisation of sodium channel NaG in the intact and injured human peripheral nervous system.

The voltage-gated 'glial' sodium channel NaG belongs to a distinct molecular class within the multi-gene family of mammalian sodium channels. Originally found in central and peripheral glia, NaG has since been detected in neurons in rat dorsal root ganglia (DRG) and may play a role in Schwann cell-axon interactions. We have studied the presence of NaG-like immunoreactivity in the intact and injured human peripheral nervous system using a specific affinity-purified antibody. Nerve fibres in normal and injured peripheral nerves and normal skin exhibited intense NaG-immunoreactivity. Numerous NaG-immunoreactive nerve fibres surrounded neuronal cell bodies within postmortem control DRG, and in DRG avulsed from the spinal cord (i.e. after traumatic central axotomy). There were no significant differences in the pattern of NaG immunostaining between control and avulsed DRG, or with delay after injury. Generally, the neuronal cell bodies were only very weakly immunoreactive to NaG, indicating that the NaG immunoreactivity was predominantly in Schwann cells/myelin. In accord, we demonstrated NaG immunostaining in cultured human and rat Schwann cells, and in distal nerve after wallerian degeneration. NaG thus appears to be a useful new marker for Schwann cells in the human PNS, and a role in neuropathy deserves investigation.

Animals↗

Expression of HGF and cMet in the peripheral nervous system of adult rats following sciatic nerve injury.

Hepatocyte growth factor (HGF) exhibits neurotrophic properties on different types of neuron, including motor, sensory and parasympathetic neurons. We demonstrate that sciatic nerve ligation induces an increase of the HGF receptor, c-met, mRNA in the distal segment of the sciatic nerve to the ligation site and a delayed elevation in the proximal segment. Immunohistochemical analysis revealed co-localization of cMet and GFAP and indicates that Schwann cells express cMet in the sciatic nerve after injury. HGF mRNA was detected in the spinal cord and DRG, and nerve injury did not alter the expression. These data demonstrate that the expression of HGF and cMet in the peripheral nervous system shows the unique pattern of regulation following nerve injury.

Animals↗

Degradation of the P0, P1, and Pr proteins in peripheral nervous system myelin by plasmin: implications regarding the role of macrophages in demyelinating diseases.

Activated macrophages secrete a variety of neutral proteinases, including plasminogen activator. Since macrophages are implicated in primary demyelination in the peripheral nervous system (PNS) in Guillain-Barré syndrome and experimental allergic neuritis, we have investigated the ability of plasmin and of conditioned media from cultured macrophages, in the presence of plasminogen, to degrade the proteins in bovine and rat PNS myelin. The results indicate that (a) the major glycoprotein P0 and the basic P1 and Pr proteins in PNS myelin are extremely sensitive to plasmin, perhaps more so than is the basic protein in CNS myelin; (b) the initial product of degradation of P0 by plasmin has a molecular weight higher than that of the "X" protein; (c) large degradation products of P0 are relatively insensitive to further degradation; and (d) the neuritogenic P2 protein in PNS myelin is quite resistant to the action of plasmin. Results similar to those with plasmin were obtained with conditioned media from macrophages and macrophage-like cell lines together with plasminogen activator, and the degradation of the PNS myelin proteins, Po and P1, under these conditions was inhibited by p-nitrophenylguanidinobenzoate, an inhibitor of plasmin and plasminogen activator. The results suggest that the macrophage plasminogen activator could participate in inflammatory demyelination in the PNS.

Animals↗

Conditional beta1-integrin gene deletion in neural crest cells causes severe developmental alterations of the peripheral nervous system.

Integrins are transmembrane receptors that are known to interact with the extracellular matrix and to be required for migration, proliferation, differentiation and apoptosis. We have generated mice with a neural crest cell-specific deletion of the beta1-integrin gene to analyse the role of beta1-integrins in neural crest cell migration and differentiation. This targeted mutation caused death within a month of birth. The loss of beta1-integrins from the embryo delayed the migration of Schwann cells along axons and induced multiple defects in spinal nerve arborisation and morphology. There was an almost complete absence of Schwann cells and sensory axon segregation and defective maturation in neuromuscular synaptogenesis. Thus, beta1-integrins are important for the control of embryonic and postnatal peripheral nervous system development.

Animals↗

Effects of L-DOPA on the concentrations of free and sulfoconjugated catecholamines in plasma, cerebrospinal fluid, urine, and central and peripheral nervous system tissues of the rat.

The effects of subcutaneous injection of L-beta-3,4-dihydroxyphenylalamine (L-DOPA) on the concentrations of the catecholamines and catecholamine sulfates in the central and peripheral nervous systems of the rat were studied. The results showed that free 3,4-dihydroxyphenylethylamine (DA, dopamine) increased rapidly and markedly in the hypothalamus and striatum after L-DOPA but DA sulfate did not change. Increased concentrations of DA sulfate were detected in the CSF and in the plasma, where it reached a concentration of 130.8 +/- 12.8 ng/ml at 2 h, seven times the level of free DA (19.1 +/- 2.9 ng/ml). In the kidney the ratio of DA sulfate to free DA was reversed in favor of free DA. Urine samples of L-DOPA-treated rats showed a higher increase of free DA than DA sulfate, but free norepinephrine (NE) and NE sulfate remained unchanged. Concentrations of free DA and free NE in the adrenal glands of L-DOPA-treated rats showed no change. Adrenal DA sulfate and NE sulfate were not detectable in the control and L-DOPA-treated rats, suggesting that the adrenal glands lack the capacity to take up or store catecholamines and their sulfate counterparts from the plasma.

Adrenal Glands↗

Evidence for the presence of L-arginine in the glial components of the peripheral nervous system.

L-Arginine is a precursor of nitric oxide that has been identified as an endogenous activator of soluble guanylate cyclase. We have recently reported the immunocytochemical localization of free L-arginine in glial cells in the central nervous system (CNS) using specific anti-arginine antibody. In the present study, we focused our attention on this particular amino acid in the peripheral nervous system (PNS). In the cochlea of the inner ear, arginine-like immunoreactivity was localized in satellite cells surrounding neurons of the spiral ganglion. In the dorsal root ganglia, satellite cells surrounding sensory neurons were found to be immunoreactive. In the superior cervical ganglion, L-arginine was concentrated in satellite cells around neuronal cells. In ganglia of the enteric plexus, supporting cells that covered neuronal cells were stained. These results show that free L-arginine in the PNS is concentrated in satellite and supporting cells, both of which correspond to glial cells in the CNS. Thus, those cells in ganglia of the PNS may support and/or control the neural activity by providing L-arginine to the neurons that they surround.

Animals↗

Distribution of calcitonin gene-related peptide in the rat peripheral nervous system with reference to its coexistence with substance P.

This immunocytochemical study, using a double-staining method, showed that calcitonin gene-related peptide-like immunoreactive structures are widely distributed in the peripheral nervous system and that many of them coexist with substance P-like immunoreactive structures in single sensory ganglion cells. Neurons positive for calcitonin gene-related peptide but negative for substance P were detected in sensory ganglia. These cells were large (about 30-45 micron in diameter); these primary sensory neurons containing calcitonin gene-related peptide can probably act independently of substance P. There were neurons containing calcitonin gene-related peptide without substance P in the pterygopalatine ganglion, although these cells were less numerous than in the sensory ganglia. In consecutive sections, calcitonin gene-related peptide-like structures occurred in thyroid parafollicular cells, which also contain calcitonin. This suggested that messenger RNA for producing calcitonin gene-related peptide is also present in the thyroid, and like calcitonin, calcitonin gene-related peptide may have a peripheral physiological role.

Animals↗