Analysis of high PSA N-CAM expression during mammalian spinal cord and peripheral nervous system development

Using a monoclonal antibody that recognizes specifically a high polysialylated form of N-CAM (high PSA N-CAM), the temporal and spatial expression of this molecule was studied in developing spinal cord and neural crest derivatives of mouse truncal region. Temporal expression was analyzed on immunoblots of spinal cord and dorsal root ganglia (DRGs) extracts microdissected at different developmental stages. Analysis of the ratio of high PSA N-CAM to total N-CAM indicated that sialylation and desialylation are independently regulated from the expression of polypeptide chains of N-CAM. Motoneurons, dorsal root ganglia cells and commissural neurons present a homogeneous distribution of high PSA N-CAMs on both their cell bodies and their neurites. Sialylation of N-CAM can occur in neurons after their aggregation in peripheral ganglia as demonstrated for dorsal root ganglia at E12. Furthermore, peripheral ganglia express different levels of high PSA N-CAM. With in vitro models using mouse neural crest cells, we found that expression of high PSA N-CAM was restricted to cells presenting an early neuronal phenotype, suggesting a common regulation for the expression of high PSA N-CAM molecules, neurofilament proteins and sodium channels. Using perturbation experiments with endoneuraminidase, we confirmed that high PSA N-CAM molecules are involved in fasciculation and neuritic growth when neurons derived from neural crest grow on collagen substrata. However, we demonstrated that these two parameters do not appear to depend on high PSA N-CAM molecules when cells were grown on a fibronectin substratum, indicating the existence of a hierarchy among adhesion molecules.

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α5GABAA receptors mediate primary afferent fiber tonic excitability in the turtle spinal cord

Journal of Neurophysiology ◽

10.1152/jn.00330.2013 ◽

2013 ◽

Vol 110 (9) ◽

pp. 2175-2184 ◽

Cited By ~ 11

Author(s):

Emanuel Loeza-Alcocer ◽

Martha Canto-Bustos ◽

Justo Aguilar ◽

Ricardo González-Ramírez ◽

Ricardo Felix ◽

...

Keyword(s):

Spinal Cord ◽

Dorsal Root Ganglia ◽

Dorsal Root ◽

Afferent Fiber ◽

Primary Afferents ◽

Equilibrium Potential ◽

Primary Afferent Depolarization ◽

Primary Afferent ◽

Dorsal Root Reflex

γ-Amino butyric acid (GABA) plays a key role in the regulation of central nervous system by activating synaptic and extrasynaptic GABAA receptors. It is acknowledged that extrasynaptic GABAA receptors located in the soma, dendrites, and axons may be activated tonically by low extracellular GABA concentrations. The activation of these receptors produces a persistent conductance that can hyperpolarize or depolarize nerve cells depending on the Cl− equilibrium potential. In an in vitro preparation of the turtle spinal cord we show that extrasynaptic α5GABAA receptors mediate the tonic state of excitability of primary afferents independently of the phasic primary afferent depolarization mediated by synaptic GABAA receptors. Blockade of α5GABAA receptors with the inverse agonist L-655,708 depressed the dorsal root reflex (DRR) without affecting the phasic increase in excitability of primary afferents. Using RT-PCR and Western blotting, we corroborated the presence of the mRNA and the α5GABAA protein in the dorsal root ganglia of the turtle spinal cord. The receptors were localized in primary afferents in dorsal root, dorsal root ganglia, and peripheral nerve terminals using immunoconfocal microscopy. Considering the implications of the DRR in neurogenic inflammation, α5GABAA receptors may serve as potential pharmacological targets for the treatment of pain.

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Oncomodulin derived from regeneration-associated macrophages in dorsal root ganglia promotes axon regeneration in the spinal cord

10.1101/2021.12.28.474322 ◽

2021 ◽

Author(s):

Min Kwon ◽

Yeojin Seo ◽

Hana Cho ◽

Jihye Choi ◽

Hyung Soon Kim ◽

...

Keyword(s):

Spinal Cord ◽

Neurite Outgrowth ◽

Dorsal Root Ganglia ◽

Axonal Regeneration ◽

Dorsal Root ◽

Axon Regeneration ◽

Signal Sequence ◽

Drg Neurons ◽

Cord Injury

Preconditioning peripheral nerve injury enhances axonal regeneration of dorsal root ganglia (DRG) neurons in part by driving pro-regenerative perineuronal macrophage activation. How these regeneration-associated macrophages influence the neuronal capacity of axon regeneration remains elusive. The present study reports that oncomodulin (ONCM) is an effector molecule derived from the regeneration-associated macrophages. ONCM was highly upregulated in DRG macrophages following preconditioning injury and necessary for the preconditioning-induced neurite outgrowth. ONCM-deficient macrophages failed to generate neurite outgrowth activity of the conditioned medium in the in vitro model of neuron-macrophage interaction. CCL2/CCR2 signaling is an upstream regulator of ONCM since the ONCM upregulation was dependent on CCR2 and CCL2 overexpression-mediated conditioning effects were attenuated in ONCM-deficient mice. Direct application of ONCM potently increased neurite outgrowth in cultured DRG neurons by activating a distinct gene set, particularly neuropeptide-related genes. AAV-mediated overexpression of ONCM construct with the signal sequence increased neuronal secretion of ONCM and enhanced neurite outgrowth in an autocrine manner. For a clinically relevant approach, we developed a nanogel-mediated system for localized delivery of recombinant ONCM to DRG tissue. Electrostatic encapsulation of ONCM by a reducible epsilon-poly(L-lysine)-nanogel (REPL-NG) resulted in a slow release of ONCM allowing sustained bioactivity. Intraganglionic injection of REPL-NG/ONCM complex achieved a remarkable long-range axonal regeneration beyond spinal cord lesion, surpassing the extent expected from the preconditioning effects. The NG-mediated ONCM delivery could be exploited as a therapeutic strategy for promoting sensory axon regeneration following spinal cord injury.

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Enhanced neuronal regeneration by retinoic acid of murine dorsal root ganglia and of fetal murine and human spinal cord in vitro

In Vitro Cellular & Developmental Biology ◽

10.1007/bf02630895 ◽

1991 ◽

Vol 27 (1) ◽

pp. 55-62 ◽

Cited By ~ 40

Author(s):

S. D. P. Quinn ◽

U. Boni

Keyword(s):

Spinal Cord ◽

Retinoic Acid ◽

Dorsal Root Ganglia ◽

Dorsal Root ◽

Neuronal Regeneration ◽

Human Spinal Cord

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Microanatomy of the Origin of the Cervical Plexus at the Spinal Cord, Nerve Root Cuffs, and Dorsal Root Ganglia Levels

Surgical Anatomy of the Cervical Plexus and its Branches ◽

10.1016/b978-0-323-83132-1.00007-x ◽

2022 ◽

pp. 93-125

Author(s):

Irene Riquelme ◽

Miguel Angel Reina ◽

André P. Boezaart ◽

Francisco Reina ◽

Virginia García-García ◽

...

Keyword(s):

Spinal Cord ◽

Dorsal Root Ganglia ◽

Nerve Root ◽

Dorsal Root ◽

Cervical Plexus

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P2X2 receptors differentiate placodal vs. neural crest C-fiber phenotypes innervating guinea pig lungs and esophagus

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.90360.2008 ◽

2008 ◽

Vol 295 (5) ◽

pp. L858-L865 ◽

Cited By ~ 81

Author(s):

Kevin Kwong ◽

Marian Kollarik ◽

Christina Nassenstein ◽

Fei Ru ◽

Bradley J. Undem

Keyword(s):

Guinea Pig ◽

Neural Crest ◽

Single Cell ◽

Dorsal Root Ganglia ◽

Dorsal Root ◽

Receptor Activation ◽

Rt Pcr ◽

C Fibers ◽

Embryonic Origin ◽

Ganglion Neurons

The lungs and esophagus are innervated by sensory neurons with somata in the nodose, jugular, and dorsal root ganglion. These sensory ganglia are derived from embryonic placode (nodose) and neural crest tissues (jugular and dorsal root ganglia; DRG). We addressed the hypothesis that the neuron's embryonic origin (e.g., placode vs. neural crest) plays a greater role in determining particular aspects of its phenotype than the environment in which it innervates (e.g., lungs vs. esophagus). This hypothesis was tested using a combination of extracellular and patch-clamp electrophysiology and single-cell RT-PCR from guinea pig neurons. Nodose, but not jugular C-fibers innervating the lungs and esophagus, responded to α,β-methylene ATP with action potential discharge that was sensitive to the P2X3 (P2X2/3) selective receptor antagonist A-317491. The somata of lung- and esophagus-specific sensory fibers were identified using retrograde tracing with a fluorescent dye. Esophageal- and lung-traced neurons from placodal tissue (nodose neurons) responded similarly to α,β-methylene ATP (30 μM) with a large sustained inward current, whereas in neurons derived from neural crest tissue (jugular and DRG neurons), the same dose of α,β-methylene ATP resulted in only a transient rapidly inactivating current or no detectable current. It has been shown previously that only activation of P2X2/3 heteromeric receptors produce sustained currents, whereas homomeric P2X3 receptor activation produces a rapidly inactivating current. Consistent with this, single-cell RT-PCR analysis revealed that the nodose ganglion neurons innervating the lungs and esophagus expressed mRNA for P2X2 and P2X3 subunits, whereas the vast majority of jugular and dorsal root ganglia innervating these tissues expressed only P2X3 mRNA with little to no P2X2 mRNA expression. We conclude that the responsiveness of C-fibers innervating the lungs and esophagus to ATP and other purinergic agonists is determined more by their embryonic origin than by the environment of the tissue they ultimately innervate.

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Genes Expressed in the Ring Gland, the Major Endocrine Organ of Drosophila melanogaster

Genetics ◽

10.1093/genetics/149.1.217 ◽

1998 ◽

Vol 149 (1) ◽

pp. 217-231

Author(s):

Peter D Harvie ◽

Maria Filippova ◽

Peter J Bryant

Keyword(s):

Reporter Gene ◽

Translational Regulation ◽

Developmental Stages ◽

System Development ◽

Elongation Factor ◽

Endocrine System ◽

Nervous System Development ◽

Enhancer Trap ◽

P Element ◽

Ring Gland

Abstract We have used an enhancer-trap approach to begin characterizing the function of the Drosophila endocrine system during larval development. Five hundred and ten different lethal PZ element insertions were screened to identify those in which a reporter gene within the P element showed strong expression in part or all of the ring gland, the major site of production and release of developmental hormones, and which had a mutant phenotype consistent with an endocrine defect. Nine strong candidate genes were identified in this screen, and eight of these are expressed in the lateral cells of the ring gland that produce ecdysteroid molting hormone (EC). We have confirmed that the genes detected by these enhancer traps are expressed in patterns similar to those detected by the reporter gene. Two of the genes encode proteins, protein kinase A and calmodulin, that have previously been implicated in the signaling pathway leading to EC synthesis and release in other insects. A third gene product, the translational elongation factor EF-1α F1, could play a role in the translational regulation of EC production. The screen also identified the genes couch potato and tramtrack, previously known from their roles in peripheral nervous system development, as being expressed in the ring gland. One enhancer trap revealed expression of the gene encoding the C subunit of vacuolar ATPase (V-ATPase) in the medial cells of the ring gland, which produce the juvenile hormone that controls progression through developmental stages. This could reveal a function of V-ATPase in the response of this part of the ring gland to adenotropic neuropeptides. However, the gene identified by this enhancer trap is ubiquitously expressed, suggesting that the enhancer trap is detecting only a subset of its control elements. The results show that the enhancer trap approach can be a productive way of exploring tissue-specific genetic functions in Drosophila.

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Neurotoxicity of Seven MEIC Chemicals Evaluated in Organotypic Cultures of Chick Embryonic Dorsal Root Ganglia

Alternatives to Laboratory Animals ◽

10.1177/026119299702500311 ◽

1997 ◽

Vol 25 (3) ◽

pp. 303-309

Author(s):

Václav Mandys ◽

Katerina Jirsová ◽

Jirí Vrana

Keyword(s):

Toxic Effect ◽

Neurite Outgrowth ◽

Dorsal Root Ganglia ◽

Dorsal Root ◽

Growth Parameters ◽

In Vitro Cytotoxicity ◽

Organotypic Cultures ◽

Response Curves ◽

Agar Culture

The neurotoxic effects of seven selected Multicenter Evaluation of In Vitro Cytotoxicity programme chemicals (methanol, ethanol, isopropanol, sodium chloride, potassium chloride, iron [II] sulphate and chloroform) were evaluated in organotypic cultures of chick embryonic dorsal root ganglia (DRG), maintained in a soft agar culture medium. Two growth parameters of neurite outgrowth from the ganglia — the mean radial length of neurites and the area of neurite outgrowth — were used to evaluate the toxicities of the chemicals. Dose-dependent decreases of both parameters were observed in all experiments. IC50 values (the concentration causing 50% inhibition of growth) were calculated from the dose-response curves established at three time-points during culture, i.e. 24, 48 and 72 hours. The lowest toxic effect was observed in cultures exposed to methanol (the IC50 ranging from 580mM to 1020mM). The highest toxic effect was observed in cultures exposed to iron (II) sulphate (the IC50 ranging from 1.2mM to 1.7mM). The results of other recent experiments suggest that organotypic cultures of DRG can be used during in vitro studies on target organ toxicity within the peripheral nervous system. Moreover, these cultures preserve the internal organisation of the tissue, maintain intercellular contacts, and thus reflect the in vitro situation, more precisely than other cell cultures.

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