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Sample records for dorsal root norm

  1. ON THE ORIGINS OF DORSAL ROOT POTENTIALS

    PubMed Central

    Lloyd, David P. C.; McIntyre, A. K.

    1949-01-01

    The "dorsal root potential" consists of five successive deflections designated for convenience, D.R.I, II, III, IV, and V. Of these, D.R.V alone constitutes the dorsal root potential of prior description. A study has been made of the general properties of those deflections not previously described. Dorsal root potentials are electrotonic extensions into the extramedullary root segment, the result of electrical interactions within the cord comparable to those that have been studied in peripheral nerve. Although the anatomical and electrical conditions of interaction are infinitely more complex in the cord than in nerve, it is seen that the fact of parallel distribution of primary afferent fibers pertaining to neighboring dorsal roots provides a sufficient anatomical basis for qualitative analysis in the first approximation of dorsal root potentials. An extension of the theory of interaction between neighboring nerve fibers has been made to include an especial case of interaction between fibers orientated at right angles to one another. The predictions have been tested in a nerve model and found correct. Given this elaboration, and the stated anatomical propositions, existing knowledge of interaction provides an adequate theoretical basis for an elementary understanding of dorsal root potentials. The study of general properties and the analysis of dorsal root potentials have led to the formulation of certain conclusions that follow. D.R.I, II, and III record the electrotonic spread of polarization resulting from the external field of impulses conducted in the intramedullary segment and longitudinal trajects of primary afferent fibers. D.R.IV arises in part as the result of activity in primary afferent fibers, and in part as the result of activity in secondary neurons. In either case the mode of production is the same, and the responsible agent is residual negativity in the active collaterals, or, more precisely, the external field of current flow about the

  2. Electrophysiological effects of lumbar dorsal root stimulation.

    PubMed

    Myklebust, J B; Maiman, D J; Larson, S J; Sances, A

    1984-06-01

    Electrical stimulation was applied to the L-5 and L-6 dorsal root ganglia of 14 monkeys with concurrent monitoring of cortical and intralaminar thalamic evoked potentials. Both responses were decreased by root stimulation, although cortical suppression required current levels 50 to 100% higher. The evoked potentials remained suppressed for periods of up to 60 minutes after 10- to 15-minute stimulation of the lumbar root electrodes. There was no increase in the duration of transmission block with longer stimulation periods. These results and available clinical data suggest that a local conduction block may be responsible for the pain relief produced by peripheral electrical stimulation. Further studies to identify more precisely the neural systems affected are required.

  3. Dorsal root vasodilatation in cat skeletal muscle.

    PubMed Central

    Hilton, S M; Marshall, J M

    1980-01-01

    1. A study has been made, in the cat anaesthetized with chloralose, of the effects of antidromic stimulation of dorsal roots L6-S1 on the blood flow through the gastrocnemius muscle. 2. Stimulation of the peripheral ends of the ligated dorsal roots with current pulses of 0.3-0.5 msec duration and at intensities most effective in activating the smaller afferent fibres, for periods of 15-20 sec, produced a 50-60% increase in muscle vascular conductance which was slow in onset and long outlasted the stimulus. 3. This muscle vasodilatation could be evoked in the paralysed animal and was unaffected by guanethidine or atropine. It was, however, greatly reduced or even abolished by the prostaglandin synthetase inhibitors, indomethacin or acetylsalicylic acid, in doses which had no effect on the dilatation produced by a local injection of acetylcholine or the functional hyperaemia induced by muscle contraction. 4. It is concluded that activity in the smaller myelinated or unmyelinated afferent fibres of skeletal muscle produces an increase in muscle blood flow which is mediated, at least in part, by prostaglandins locally synthesized within the muscle. PMID:7381769

  4. Calcium Signaling in Intact Dorsal Root Ganglia

    PubMed Central

    Gemes, Geza; Rigaud, Marcel; Koopmeiners, Andrew S.; Poroli, Mark J.; Zoga, Vasiliki; Hogan, Quinn H.

    2013-01-01

    Background Ca2+ is the dominant second messenger in primary sensory neurons. In addition, disrupted Ca2+ signaling is a prominent feature in pain models involving peripheral nerve injury. Standard cytoplasmic Ca2+ recording techniques use high K+ or field stimulation and dissociated neurons. To compare findings in intact dorsal root ganglia, we used a method of simultaneous electrophysiologic and microfluorimetric recording. Methods Dissociated neurons were loaded by bath-applied Fura-2-AM and subjected to field stimulation. Alternatively, we adapted a technique in which neuronal somata of intact ganglia were loaded with Fura-2 through an intracellular microelectrode that provided simultaneous membrane potential recording during activation by action potentials (APs) conducted from attached dorsal roots. Results Field stimulation at levels necessary to activate neurons generated bath pH changes through electrolysis and failed to predictably drive neurons with AP trains. In the intact ganglion technique, single APs produced measurable Ca2+ transients that were fourfold larger in presumed nociceptive C-type neurons than in nonnociceptive Aβ-type neurons. Unitary Ca2+ transients summated during AP trains, forming transients with amplitudes that were highly dependent on stimulation frequency. Each neuron was tuned to a preferred frequency at which transient amplitude was maximal. Transients predominantly exhibited monoexponential recovery and had sustained plateaus during recovery only with trains of more than 100 APs. Nerve injury decreased Ca2+ transients in C-type neurons, but increased transients in Aβ-type neurons. Conclusions Refined observation of Ca2+ signaling is possible through natural activation by conducted APs in undissociated sensory neurons and reveals features distinct to neuronal types and injury state. PMID:20526180

  5. Neuronal cell lines as model dorsal root ganglion neurons

    PubMed Central

    Yin, Kathleen; Baillie, Gregory J

    2016-01-01

    Background Dorsal root ganglion neuron-derived immortal cell lines including ND7/23 and F-11 cells have been used extensively as in vitro model systems of native peripheral sensory neurons. However, while it is clear that some sensory neuron-specific receptors and ion channels are present in these cell lines, a systematic comparison of the molecular targets expressed by these cell lines with those expressed in intact peripheral neurons is lacking. Results In this study, we examined the expression of RNA transcripts in the human neuroblastoma-derived cell line, SH-SY5Y, and two dorsal root ganglion hybridoma cell lines, F-11 and ND7/23, using Illumina next-generation sequencing, and compared the results with native whole murine dorsal root ganglions. The gene expression profiles of these three cell lines did not resemble any specific defined dorsal root ganglion subclass. The cell lines lacked many markers for nociceptive sensory neurons, such as the Transient receptor potential V1 gene, but expressed markers for both myelinated and unmyelinated neurons. Global gene ontology analysis on whole dorsal root ganglions and cell lines showed similar enrichment of biological process terms across all samples. Conclusions This paper provides insights into the receptor repertoire expressed in common dorsal root ganglion neuron-derived cell lines compared with whole murine dorsal root ganglions, and illustrates the limits and potentials of these cell lines as tools for neuropharmacological exploration. PMID:27130590

  6. Involvement of dorsal root ganglia in Fabry's disease.

    PubMed

    Gadoth, N; Sandbank, U

    1983-08-01

    Bouts of shooting pain along the extremities are common in the early stages of Fabry's disease. No pathological explanation has been advanced to clarify the mechanism of such pain. In the present case neuronal storage of glycolipid was confined to dorsal root ganglia neurones only. It is suggested that this may explain the shooting pain in Fabry's disease. In hereditary sensory radicular neuropathy, familial dysautonomia, and tabes dorsalis, changes in dorsal root ganglia cells cause similar clinical signs and thus it may be concluded that shooting pains in Fabry's disease may be caused by damage to dorsal root ganglia neurones.

  7. Involvement of dorsal root ganglia in Fabry's disease.

    PubMed Central

    Gadoth, N; Sandbank, U

    1983-01-01

    Bouts of shooting pain along the extremities are common in the early stages of Fabry's disease. No pathological explanation has been advanced to clarify the mechanism of such pain. In the present case neuronal storage of glycolipid was confined to dorsal root ganglia neurones only. It is suggested that this may explain the shooting pain in Fabry's disease. In hereditary sensory radicular neuropathy, familial dysautonomia, and tabes dorsalis, changes in dorsal root ganglia cells cause similar clinical signs and thus it may be concluded that shooting pains in Fabry's disease may be caused by damage to dorsal root ganglia neurones. Images PMID:6413695

  8. Identification of oxytocin receptor in the dorsal horn and nociceptive dorsal root ganglion neurons.

    PubMed

    Moreno-López, Y; Martínez-Lorenzana, G; Condés-Lara, M; Rojas-Piloni, G

    2013-04-01

    Oxytocin (OT) secreted by the hypothalamo-spinal projection exerts antinociceptive effects in the dorsal horn. Electrophysiological evidence indicates that OT could exert these effects by activating OT receptors (OTR) directly on dorsal horn neurons and/or primary nociceptive afferents in the dorsal root ganglia (DRG). However, little is known about the identity of the dorsal horn and DRG neurons that express the OTR. In the dorsal horn, we found that the OTR is expressed principally in neurons cell bodies. However, neither spino-thalamic dorsal horn neurons projecting to the contralateral thalamic ventral posterolateral nucleus (VPL) and posterior nuclear group (Po) nor GABaergic dorsal horn neurons express the OTR. The OTR is not expressed in skin nociceptive terminals or in dorsal horn nociceptive fibers. In the DRG, however, the OTR is expressed predominantly in non-peptidergic C-fiber cell bodies, but not in peptidergic or mechanoreceptor afferents or in skin nociceptive terminals. Our results suggest that the antinociceptive effects of OT are mediated by direct activation of dorsal horn neurons and peripheral actions on nociceptive, non-peptidergic C-afferents in the DRG.

  9. Intracerebroventricular administration of nerve growth factor induces gliogenesis in sensory ganglia, dorsal root, and within the dorsal root entry zone.

    PubMed

    Schlachetzki, Johannes C M; Pizzo, Donald P; Morrissette, Debbi A; Winkler, Jürgen

    2014-01-01

    Previous studies indicated that intracerebroventricular administration of nerve growth factor (NGF) leads to massive Schwann cell hyperplasia surrounding the medulla oblongata and spinal cord. This study was designed to characterize the proliferation of peripheral glial cells, that is, Schwann and satellite cells, in the trigeminal ganglia and dorsal root ganglia (DRG) of adult rats during two weeks of NGF infusion using bromodeoxyuridine (BrdU) to label dividing cells. The trigeminal ganglia as well as the cervical and lumbar DRG were analyzed. Along the entire neuraxis a small number of dividing cells were observed within these regions under physiological condition. NGF infusion has dramatically increased the generation of new cells in the neuronal soma and axonal compartments of sensory ganglia and along the dorsal root and the dorsal root entry zone. Quantification of BrdU positive cells within sensory ganglia revealed a 2.3- to 3-fold increase in glial cells compared to controls with a similar response to NGF for the different peripheral ganglia examined. Immunofluorescent labeling with S100β revealed that Schwann and satellite cells underwent mitosis after NGF administration. These data indicate that intracerebroventricular NGF infusion significantly induces gliogenesis in trigeminal ganglia and the spinal sensory ganglia and along the dorsal root entry zone as well as the dorsal root.

  10. Antidromic discharges of dorsal root afferents in the neonatal rat.

    PubMed

    Vinay, L; Brocard, F; Fellippa-Marques, S; Clarac, F

    1999-01-01

    Presynaptic inhibition of primary afferents can be evoked from at least three sources in the adult animal: 1) by stimulation of several supraspinal structures; 2) by spinal reflex action from sensory inputs; or 3) by the activity of spinal locomotor networks. The depolarisation in the intraspinal afferent terminals which is due, at least partly, to the activation of GABA(A) receptors may be large enough to reach firing threshold and evoke action potentials that are antidromically conducted into peripheral nerves. Little is known about the development of presynaptic inhibition and its supraspinal control during ontogeny. This article, reviewing recent experiments performed on the in vitro brainstem/spinal cord preparation of the neonatal rat, demonstrates that a similar organisation is present, to some extent, in the new-born rat. A spontaneous activity consisting of antidromic discharges can be recorded from lumbar dorsal roots. The discharges are generated by the underlying afferent terminal depolarizations reaching firing threshold. The number of antidromic action potentials increases significantly in saline solution with chloride concentration reduced to 50% of control. Bath application of the GABA(A) receptor antagonist, bicuculline (5-10 microM) blocks the antidromic discharges almost completely. Dorsal root discharges are therefore triggered by chloride-dependent GABA(A) receptor-mediated mechanisms; 1) activation of descending pathways by stimulation delivered to the ventral funiculus (VF) of the spinal cord at the C1 level; 2) activation of sensory inputs by stimulation of a neighbouring dorsal root; or 3) pharmacological activation of the central pattern generators for locomotion evokes antidromic discharges in dorsal roots. VF stimulation also inhibited the response to dorsal root stimulation. The time course of this inhibition overlapped with that of the dorsal root discharge suggesting that part of the inhibition of the monosynaptic reflex may be

  11. Vulnerability of dorsal root neurons and fibers toward methylmercury toxicity: a morphological evaluation

    SciTech Connect

    Yip, R.K.; Chang, L.W.

    1981-10-01

    The selective and relative sensitivity of various components (dorsal root neurons, dorsal root fibers, and ventral root fibers) of the dorsal root ganglia toward methylmercury toxicity were investigated. Charles River rats were orally administered methymercury chloride at a daily dose of 2.0 mg/kg body wt for 8 weeks. Dorsal root ganglia (L/sub 1/-S/sub 1/) were examined with light and electron microscopy. Extensive Wallerian-like degeneration was observed in the dorsal root fibers while no significant changes were found in the dorsal root neurons and in the ventral root fibers at the light-microscopic level. At the electron-microscopic level, only minor and possibly reversible changes, such as increase in lysosomes, neurofilamentous proliferation, and disintegration of the Nissl substance, were observed in the neuronal cell bodies while severe and irreversible degenerative changes occurred in the dorsal root fibers. No remarkable pathological changes were observed in the ventral root fibers. Schwann cells became hypertrophied and transformed into actively phagocytosing macrophages. It is concluded that while the dorsal root ganglia are highly vulnerable to the toxicity of methylmercury, the relative sensitivity to the toxic impact is: dorsal root fiber > dorsal root neuron (nerve cell body) > ventral root fibers.

  12. Position of dorsal root ganglia in the lumbosacral region in patients with radiculopathy

    PubMed Central

    Moon, Hyun Seog; Kim, Yeon Dong; Song, Bang Hoon; Cha, Young Deog; Song, Jang Ho

    2010-01-01

    Background When applying pulsed radiofrequency on dorsal root ganglia for treating chronic lower back pain, maximum efficiency can be expected when a needle is placed 1-2 cm peripheral to the dorsal root ganglion. The object of this study is to analyze images taken after adding contrast to transforaminal epidural injection, categorize root ganglia according to anatomical position, and provide a reference for efficient needle positioning in applying pulsed radiofrequency on dorsal root ganglia. Methods From January 2008 to January 2009, 457 patients who visited our hospital for root pain or radiculopathy were treated with transforaminal epidural injection on the nerve roots based on the dermatome of the painful area. Anteroposterior views were taken after injection of contrast. A virtual line was made by connecting the internal and external parts of the spinal pedicle from the contrast images. Then the dorsal root ganglia were categorized as intraspinal (IS), intraforaminal (IF), or extraforaminal (EF). Results In the fourth lumbar spine, dorsal root ganglia positions were 48% IF, 41% IS, and 6% EF. In the fifth lumbar spine, dorsal root ganglia positions were 75% IF, 10% IS, and 6% EF. In the first sacral spine, dorsal root ganglia locations were 8% IF and 83% IS. Conclusions Positional categorization of dorsal root ganglia according to contrast images was proven to be good anatomical references for effective radiofrequency or blocking of dorsal root ganglia. PMID:21253377

  13. AAV-Mediated Gene Transfer to Dorsal Root Ganglion.

    PubMed

    Yu, Hongwei; Fischer, Gregory; Hogan, Quinn H

    2016-01-01

    Transferring genetic molecules into the peripheral sensory nervous system to manipulate nociceptive pathophysiology is a powerful approach for experimental modulation of sensory signaling and potentially for translation into therapy for chronic pain. This can be efficiently achieved by the use of recombinant adeno-associated virus (rAAV) in conjunction with nociceptor-specific regulatory transgene cassettes. Among different routes of delivery, direct injection into the dorsal root ganglia (DRGs) offers the most efficient AAV-mediated gene transfer selectively into the peripheral sensory nervous system. Here, we briefly discuss the advantages and applications of intraganglionic microinjection, and then provide a detailed approach for DRG injection, including a list of the necessary materials and description of a method for performing DRG microinjection experiments. We also discuss our experience with several adeno-associated virus (AAV) options for in vivo transgene expression in DRG neurons.

  14. Primary Postnatal Dorsal Root Ganglion Culture from Conventionally Slaughtered Calves

    PubMed Central

    Fadda, A.; Bärtschi, M.; Hemphill, A.; Widmer, H. R.; Zurbriggen, A.; Perona, P.; Vidondo, B.; Oevermann, A.

    2016-01-01

    Neurological disorders in ruminants have an important impact on veterinary health, but very few host-specific in vitro models have been established to study diseases affecting the nervous system. Here we describe a primary neuronal dorsal root ganglia (DRG) culture derived from calves after being conventionally slaughtered for food consumption. The study focuses on the in vitro characterization of bovine DRG cell populations by immunofluorescence analysis. The effects of various growth factors on neuron viability, neurite outgrowth and arborisation were evaluated by morphological analysis. Bovine DRG neurons are able to survive for more than 4 weeks in culture. GF supplementation is not required for neuronal survival and neurite outgrowth. However, exogenously added growth factors promote neurite outgrowth. DRG cultures from regularly slaughtered calves represent a promising and sustainable host specific model for the investigation of pain and neurological diseases in bovines. PMID:27936156

  15. Inhibitory Injury Signaling Represses Axon Regeneration After Dorsal Root Injury.

    PubMed

    Mar, Fernando M; Simões, Anabel R; Rodrigo, Inês S; Sousa, Mónica M

    2016-09-01

    Following injury to peripheral axons, besides increased cyclic adenosine monophosphate (cAMP), the positive injury signals extracellular-signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and signal transducer and activator of transcription 3 (STAT-3) are locally activated and retrogradely transported to the cell body, where they induce a pro-regenerative program. Here, to further understand the importance of injury signaling for successful axon regeneration, we used dorsal root ganglia (DRG) neurons that have a central branch without regenerative capacity and a peripheral branch that regrows after lesion. Although injury to the DRG central branch (dorsal root injury (DRI)) activated ERK, JNK, and STAT-3 and increased cAMP levels, it did not elicit gain of intrinsic growth capacity nor the ability to overcome myelin inhibition, as occurred after peripheral branch injury (sciatic nerve injury (SNI)). Besides, gain of growth capacity after SNI was independent of ERK and cAMP. Antibody microarrays of dynein-immunoprecipitated axoplasm from rats with either DRI or SNI revealed a broad differential activation and transport of signals after each injury type and further supported that ERK, JNK, STAT-3, and cAMP signaling pathways are minor contributors to the differential intrinsic axon growth capacity of both injury models. Increased levels of inhibitory injury signals including GSK3β and ROCKII were identified after DRI, not only in axons but also in DRG cell bodies. In summary, our work shows that activation and transport of positive injury signals are not sufficient to promote increased axon growth capacity and that differential modulation of inhibitory molecules may contribute to limited regenerative response.

  16. EVALUATION OF HYPERALGESIA AND HISTOLOGICAL CHANGES OF DORSAL ROOT GANGLION INDUCED BY NUCLEUS PULPOSUS

    PubMed Central

    Grava, André Luiz de Souza; Ferrari, Luiz Fernando; Parada, Carlos Amílcar; Defino, Helton Luiz Aparecido

    2015-01-01

    To evaluate the hyperalgesia and histological abnormalities induced by contact between the dorsal root ganglion and the nucleus pulposus. Methods: Twenty Wistar rats were used, divided into two experimental groups. In one of the groups, a fragment of autologous nucleus pulposus was removed from the sacrococcygeal region and deposited on the L5 dorsal root ganglia. In the other group (control), a fragment of adipose tissue was deposited on the L5 dorsal root ganglia. Mechanical and thermal hyperalgesia was evaluated on the third day and the first, third, fifth and seventh weeks after the operation. A L5 dorsal root ganglion was removed in the first, third, fifth and seventh weeks after the operation for histological study using HE staining and histochemical study using specific labeling for iNOS. Results: Higher intensity of mechanical and thermal hyperalgesia was observed in the group of animals in which the nucleus pulposus was placed in contact with the dorsal root ganglion. In this group, the histological study showed abnormalities of the dorsal root ganglion tissue, characterized by an inflammatory process and axonal degeneration. The histopathological abnormalities of the dorsal root ganglion tissue presented increasing intensity with increasing length of observation, and there was a correlation with maintenance of the hyperalgesia observed in the behavioral assessment. Immunohistochemistry using specific labeling for iNOS in the group of animals in which the nucleus pulposus was placed in contact with the dorsal root ganglion showed higher expression of this enzyme in the nuclei of the inflammatory cells (glial cells) surrounding the neurons. Conclusion: Contact between the nucleus pulposus and the dorsal root ganglion induced mechanical and thermal hyperalgesia and caused histological abnormalities in the dorsal root ganglion components. These abnormalities were characterized by an inflammatory and degenerative process in the structures of the dorsal root

  17. Visualizing sensory transmission between dorsal root ganglion and dorsal horn neurons in co-culture with calcium imaging.

    PubMed

    Ohshiro, Hiroyuki; Ogawa, Shinji; Shinjo, Katsuhiro

    2007-09-15

    Sensory information is conveyed to the central nervous system by primary afferent neurons within dorsal root ganglia (DRG), which synapse onto neurons of the dorsal horn of the spinal cord. This synaptic connection is central to the processing of both sensory and pain stimuli. Here, we describe a model system to monitor synaptic transmission between DRG neurons and dorsal horn neurons that is compatible with high-throughput screening. This co-culture preparation comprises DRG and dorsal horn neurons and utilizes Ca(2+) imaging with the indicator dye Fura-2 to visualize synaptic transmission. Addition of capsaicin to co-cultures stimulated DRG neurons and led to activation of dorsal horn neurons as well as increased intracellular Ca(2+) concentrations. This effect was dose-dependent and absent when DRG neurons were omitted from the culture. NMDA receptors are a critical component of synapses between DRG and dorsal horn neurons as MK-801, a use-dependent non-competitive antagonist, prevented activation of dorsal horn neurons following capsaicin treatment. This model system allows for rapid and efficient analysis of noxious stimulus-evoked Ca(2+) signal transmission and provides a new approach both for investigating synaptic transmission in the spinal cord and for screening potential analgesic compounds.

  18. Microglia enhance dorsal root ganglion outgrowth in Schwann cell cultures.

    PubMed

    Hynds, Dianna L; Rangappa, Nagarathnamma; Ter Beest, Julia; Snow, Diane M; Rabchevsky, Alexander G

    2004-04-15

    Transplantation of cellular populations to facilitate regrowth of damaged axons is a common experimental therapy for spinal cord injury. Schwann cells (SC) or microglia grafted into injury sites can promote axonal regrowth of central projections of dorsal root ganglion (DRG) sensory neurons. We sought to determine whether the addition of microglia or microglia-derived secretory products alters DRG axon regrowth upon cultures of SC. Rat DRG explants were grown on monolayers consisting of either SC, microglia, SC exposed to microglia-conditioned medium (MCM), or co-cultures with different relative concentrations of microglia. Image analysis revealed that, compared to SC alone, the extent of neurite outgrowth was significantly greater on SC-microglia co-cultures. Immunocytochemistry for extracellular matrix molecules showed that microglial cells stained positively for growth-promoting thrombospondin, whereas laminin and the inhibitory chondroitin sulfate proteoglycans (CSPGs) were localized primarily to SC. Notably, immunoreactivity for CSPGs appeared reduced in areas associated with DRG outgrowth in co-cultures and SC exposed to MCM. These results show that microglia or their secreted products can augment SC-mediated DRG regrowth in vitro, indicating that co-grafting SC with microglia provides a novel approach to augment sensory fiber regeneration after spinal cord injury.

  19. Pharmacologically novel GABA receptor in human dorsal root ganglion neurons.

    PubMed

    Valeyev, A Y; Hackman, J C; Wood, P M; Davidoff, R A

    1996-11-01

    1. Whole cell voltage-clamp studies of gamma-aminobutyric acid (GABA) receptors were performed on large (> 80 microns) cultured human dorsal root ganglion (DRG) neurons. 2. GABA and pentobarbital sodium when applied in micromolar concentrations evoked inward Cl- currents in DRG neurons voltage clamped at negative membrane potentials. 3. Diazepam (10 microM) and pentobarbital (10 microM) upmodulated the GABA current by approximately 149 and 168%, respectively. 4. The GABA currents in human DRG cells were unaffected by the classical GABA antagonists picrotoxin and bicuclline (100 microM). In contrast, the GABA responses evoked in adult rat DRG cells cultured in an identical manner were inhibited by both antagonists. The glycine receptor antagonist strychnine (100 microM) did not alter GABA currents in human DRG cells. 5. Human DRG cells did not respond to glycine (10-100 microM) or taurine (10-100 microM). The GABAB agonist baclofen had no effect on the holding current when patch pipettes were filled with 130 mM KCl. The GABAB antagonists saclofen applied either alone or with GABA was without effect. 6. The differences between the GABA receptors described here and GABA receptors in other species may reflect the presence of receptor subunits unique to human DRG cells.

  20. Reinnervation of hind limb extremity after lumbar dorsal root ganglion injury.

    PubMed

    Liu, Song; Bréjot, Thomas; Cressant, Arnaud; Bacci, Josette; Saïd, Gérard; Tadié, Marc; Heard, Jean Michel

    2005-12-01

    Loss of dorsal root ganglion neuron, or injury to dorsal roots, induces permanent somatosensory defect without therapeutic option. We explored an approach to restoring hind limb somatosensory innervation after elimination of L4, L5 and L6 dorsal root ganglion neurons in rats. Somatosensory pathways were reconstructed by connecting L4, L5 and L6 lumbar dorsal roots to T10, T11 and T12 intercostal nerves, respectively, thus allowing elongation of thoracic ganglion neuron peripheral axons into the sciatic nerve. Connection of thoracic dorsal root ganglion neurons to peripheral tissues was documented 4 and 7 months after injury. Myelinated and unmyelinated fibers regrew in the sciatic nerve. Nerve terminations expressing calcitonin-gene-related-peptide colonized the footpad skin. Retrograde tracing showed that T10, T11 and T12 dorsal root ganglion neurons expressing calcitonin-gene-related-peptide or the neurofilament RT97 projected axons to the sciatic nerve and the footpad skin. Recording of somatosensory evoked potentials in the upper spinal cord indicated connection between the sciatic nerve and the central nervous system. Hind limb retraction in response to nociceptive stimulation of the reinnervated footpads and reversion of skin lesions suggested partial recovery of sensory function. Proprioceptive defects persisted. Delayed somatosensory reinnervation of the hind limb after destruction of lumbar dorsal root neurons in rats indicates potential approaches to reduce chronic disability after severe injury to somatosensory pathways.

  1. Human dorsal root ganglion in vivo morphometry and perfusion in Fabry painful neuropathy.

    PubMed

    Godel, Tim; Bäumer, Philipp; Pham, Mirko; Köhn, Anja; Muschol, Nicole; Kronlage, Moritz; Kollmer, Jennifer; Heiland, Sabine; Bendszus, Martin; Mautner, Victor-Felix

    2017-09-19

    To evaluate functional and morphometric magnetic resonance neurography of the dorsal root ganglion and peripheral nerve segments in patients with Fabry painful neuropathy. In this prospective study, the lumbosacral dorsal root ganglia and proximal peripheral nerve segments of the lower extremity were examined in 11 male patients with Fabry disease by a standardized 3T magnetic resonance neurography protocol. Volumes of L3 to S2 dorsal root ganglia, perfusion parameters of L5-S1 dorsal root ganglia and the spinal nerve L5, and the cross-sectional area of the proximal sciatic nerve were compared to healthy controls. Dorsal root ganglia of patients with Fabry disease were symmetrically enlarged by 78% (L3), 94% (L4), 122% (L5), 115% (S1), and 119% (S2) (p < 0.001). In addition, permeability of the blood-tissue interface was decreased by 53% (p < 0.001). This finding was most pronounced in the peripheral zone of the dorsal root ganglion containing the cell bodies of the primary sensory neurons (p < 0.001). Spinal nerve permeability showed no difference between patients with Fabry disease and controls (p = 0.7). The sciatic nerve of patients with Fabry disease at the thigh level showed an increase in cross-sectional area by 48% (p < 0.001). Patients with Fabry disease have severely enlarged dorsal root ganglia with dysfunctional perfusion. This may be due to glycolipid accumulation in the dorsal root ganglia mediating direct neurotoxic effects and decreased neuronal blood supply. These alterations were less pronounced in peripheral nerve segments. Thus, the dorsal root ganglion might play a key pathophysiologic role in the development of neuropathy and pain in Fabry disease. © 2017 American Academy of Neurology.

  2. Expressing Constitutively Active Rheb in Adult Dorsal Root Ganglion Neurons Enhances the Integration of Sensory Axons that Regenerate Across a Chondroitinase-Treated Dorsal Root Entry Zone Following Dorsal Root Crush

    PubMed Central

    Wu, Di; Klaw, Michelle C.; Kholodilov, Nikolai; Burke, Robert E.; Detloff, Megan R.; Côté, Marie-Pascale; Tom, Veronica J.

    2016-01-01

    While the peripheral branch of dorsal root ganglion neurons (DRG) can successfully regenerate after injury, lesioned central branch axons fail to regrow across the dorsal root entry zone (DREZ), the interface between the dorsal root and the spinal cord. This lack of regeneration is due to the limited regenerative capacity of adult sensory axons and the growth-inhibitory environment at the DREZ, which is similar to that found in the glial scar after a central nervous system (CNS) injury. We hypothesized that transduction of adult DRG neurons using adeno-associated virus (AAV) to express a constitutively-active form of the GTPase Rheb (caRheb) will increase their intrinsic growth potential after a dorsal root crush. Additionally, we posited that if we combined that approach with digestion of upregulated chondroitin sulfate proteoglycans (CSPG) at the DREZ with chondroitinase ABC (ChABC), we would promote regeneration of sensory axons across the DREZ into the spinal cord. We first assessed if this strategy promotes neuritic growth in an in vitro model of the glial scar containing CSPG. ChABC allowed for some regeneration across the once potently inhibitory substrate. Combining ChABC treatment with expression of caRheb in DRG significantly improved this growth. We then determined if this combination strategy also enhanced regeneration through the DREZ after dorsal root crush in adult rats in vivo. After unilaterally crushing C4-T1 dorsal roots, we injected AAV5-caRheb or AAV5-GFP into the ipsilateral C5-C8 DRGs. ChABC or PBS was injected into the ipsilateral dorsal horn at C5-C8 to digest CSPG, for a total of four animal groups (caRheb + ChABC, caRheb + PBS, GFP + ChABC, GFP + PBS). Regeneration was rarely observed in PBS-treated animals, whereas short-distance regrowth across the DREZ was observed in ChABC-treated animals. No difference in axon number or length between the ChABC groups was observed, which may be related to intraganglionic inflammation induced by the

  3. Expressing Constitutively Active Rheb in Adult Dorsal Root Ganglion Neurons Enhances the Integration of Sensory Axons that Regenerate Across a Chondroitinase-Treated Dorsal Root Entry Zone Following Dorsal Root Crush.

    PubMed

    Wu, Di; Klaw, Michelle C; Kholodilov, Nikolai; Burke, Robert E; Detloff, Megan R; Côté, Marie-Pascale; Tom, Veronica J

    2016-01-01

    While the peripheral branch of dorsal root ganglion neurons (DRG) can successfully regenerate after injury, lesioned central branch axons fail to regrow across the dorsal root entry zone (DREZ), the interface between the dorsal root and the spinal cord. This lack of regeneration is due to the limited regenerative capacity of adult sensory axons and the growth-inhibitory environment at the DREZ, which is similar to that found in the glial scar after a central nervous system (CNS) injury. We hypothesized that transduction of adult DRG neurons using adeno-associated virus (AAV) to express a constitutively-active form of the GTPase Rheb (caRheb) will increase their intrinsic growth potential after a dorsal root crush. Additionally, we posited that if we combined that approach with digestion of upregulated chondroitin sulfate proteoglycans (CSPG) at the DREZ with chondroitinase ABC (ChABC), we would promote regeneration of sensory axons across the DREZ into the spinal cord. We first assessed if this strategy promotes neuritic growth in an in vitro model of the glial scar containing CSPG. ChABC allowed for some regeneration across the once potently inhibitory substrate. Combining ChABC treatment with expression of caRheb in DRG significantly improved this growth. We then determined if this combination strategy also enhanced regeneration through the DREZ after dorsal root crush in adult rats in vivo. After unilaterally crushing C4-T1 dorsal roots, we injected AAV5-caRheb or AAV5-GFP into the ipsilateral C5-C8 DRGs. ChABC or PBS was injected into the ipsilateral dorsal horn at C5-C8 to digest CSPG, for a total of four animal groups (caRheb + ChABC, caRheb + PBS, GFP + ChABC, GFP + PBS). Regeneration was rarely observed in PBS-treated animals, whereas short-distance regrowth across the DREZ was observed in ChABC-treated animals. No difference in axon number or length between the ChABC groups was observed, which may be related to intraganglionic inflammation induced by the

  4. Purification and culture of adult rat dorsal root ganglia neurons.

    PubMed

    Delree, P; Leprince, P; Schoenen, J; Moonen, G

    1989-06-01

    To study the trophic requirements of adult rat dorsal root ganglia neurons (DRG) in vitro, we developed a purification procedure that yields highly enriched neuronal cultures. Forty to fifty ganglia are dissected from the spinal column of an adult rat. After enzymatic and mechanical dissociation of the ganglia, myelin debris are eliminated by centrifugation on a Percoll gradient. The resulting cell suspension is layered onto a nylon mesh with a pore size of 10 microns. Most of the neurons, the diameter of which ranged from 17 microns to greater than 100 microns, are retained on the upper surface of the sieve; most of the non-neuronal cells with a caliber of less than 10 microns after trypsinization go through it. Recovery of neurons is achieved by reversing the mesh onto a Petri dish containing culture medium. Neurons to non-neurons ratio is 1 to 10 in the initial cell suspension and 1 to 1 after separation. When these purified neurons are seeded at a density of 3,000 neurons/cm2 in 6 mm polyornithine-laminin (PORN-LAM) coated wells, neuronal survival (assessed by the ability to extend neurites), measured after 48 hr of culture, is very low (from 0 to 16%). Addition of nerve growth factor (NGF) does not improve neuronal survival. However, when neurons are cultured in the presence of medium conditioned (CM) by astrocytes or Schwann cells, 60-80% of the seeded, dye-excluding neurons survive. So, purified adult DRG neurons require for their short-term survival and regeneration in culture, a trophic support that is present in conditioned medium from PNS or CNS glia.(ABSTRACT TRUNCATED AT 250 WORDS)

  5. Retentive multipotency of adult dorsal root ganglia stem cells.

    PubMed

    Singh, Rabindra P; Cheng, Ying-Hua; Nelson, Paul; Zhou, Feng C

    2009-01-01

    Preservation of neural stem cells (NSCs) in the adult peripheral nervous system (PNS) has recently been confirmed. However, it is not clear whether peripheral NSCs possess predestined, bona fide phenotypes or a response to innate developmental cues. In this study, we first demonstrated the longevity, multipotency, and high fidelity of sensory features of postmigrating adult dorsal root ganglia (aDRG) stem cells. Derived from aDRG and after 4-5 years in culture without dissociating, the aDRG NSCs were found capable of proliferation, expressing neuroepithelial, neuronal, and glial markers. Remarkably, these aDRG NSCs expressed sensory neuronal markers vesicular glutamate transporter 2 (VGluT2--glutamate terminals), transient receptor potential vanilloid 1 (TrpV1--capsaicin sensitive), phosphorylated 200 kDa neurofilaments (pNF200--capsaicin insensitive, myelinated), and the serotonin transporter (5-HTT), which normally is transiently expressed in developing DRG. Furthermore, in response to neurotrophins, the aDRG NSCs enhanced TrpV1 expression upon exposure to nerve growth factor (NGF), but not to brain-derived neurotrophic factor (BDNF). On the contrary, BDNF increased the expression of NeuN. Third, the characterization of aDRG NSCs was demonstrated by transplantation of red fluorescent-expressing aDRG NSCs into injured spinal cord. These cells expressed nestin, Hu, and beta-III-tubulin (immature neuronal markers), GFAP (astrocyte marker) as well as sensory neural marker TrpV1 (capsaicin sensitive) and pNF200 (mature, capsaicin insensitive, myelinated). Our results demonstrated that the postmigrating neural crest adult DRG stem cells not only preserved their multipotency but also were retentive in sensory potency despite the age and long-term ex vivo status.

  6. Chronic sciatic nerve compression induces fibrosis in dorsal root ganglia.

    PubMed

    Li, Qinwen; Chen, Jianghai; Chen, Yanhua; Cong, Xiaobin; Chen, Zhenbing

    2016-03-01

    In the present study, pathological alterations in neurons of the dorsal root ganglia (DRG) were investigated in a rat model of chronic sciatic nerve compression. The rat model of chronic sciatic nerve compression was established by placing a 1 cm Silastic tube around the right sciatic nerve. Histological examination was performed via Masson's trichrome staining. DRG injury was assessed using Fluoro Ruby (FR) or Fluoro Gold (FG). The expression levels of target genes were examined using reverse transcription‑quantitative polymerase chain reaction, western blot and immunohistochemical analyses. At 3 weeks post‑compression, collagen fiber accumulation was observed in the ipsilateral area and, at 8 weeks, excessive collagen formation with muscle atrophy was observed. The collagen volume fraction gradually and significantly increased following sciatic nerve compression. In the model rats, the numbers of FR‑labeled DRG neurons were significantly higher, relative to the sham‑operated group, however, the numbers of FG‑labeled neurons were similar. In the ipsilateral DRG neurons of the model group, the levels of transforming growth factor‑β1 (TGF‑β1) and connective tissue growth factor (CTGF) were elevated and, surrounding the neurons, the levels of collagen type I were increased, compared with those in the contralateral DRG. In the ipsilateral DRG, chronic nerve compression was associated with significantly higher levels of phosphorylated (p)‑extracellular signal‑regulated kinase 1/2, and significantly lower levels of p‑c‑Jun N‑terminal kinase and p‑p38, compared with those in the contralateral DRGs. Chronic sciatic nerve compression likely induced DRG pathology by upregulating the expression levels of TGF‑β1, CTGF and collagen type I, with involvement of the mitogen‑activated protein kinase signaling pathway.

  7. Modified dorsal root entry zone lesioning for intractable pain relief in patients with root avulsion injury.

    PubMed

    Takai, Keisuke; Taniguchi, Makoto

    2017-08-01

    OBJECTIVE Dorsal root entry zone (DREZ) lesioning has been the most effective surgical treatment for the relief of intractable pain due to root avulsion injury, but residual pain and a decrease in pain relief in the follow-up period have been reported in 23%-70% of patients. Based on pain topography in the most recent studies on neuropathic pain, the authors modified the conventional DREZ lesioning procedure to improve clinical outcomes. The presumed rationale for this procedure is to eliminate the spontaneous discharges of neurons in the superficial spinal dorsal horn as well as wide dynamic range neurons in the deep spinal dorsal horn. METHODS Ten patients with avulsion-related pain underwent surgery between 2011 and 2015. The surgical procedure was described and postoperative pain relief was assessed as follows: excellent (residual pain never exceeded 3 on the visual analog scale [VAS] without medication), good (residual pain never exceeded 5 on the VAS with medication), and poor (residual pain was greater than 5 with medication). Specific perioperative complications were assessed. RESULTS The aim of this surgical procedure was to destroy the deeper layers of the posterior horn of spinal gray matter, which was in contrast to the procedures of Nashold and Sindou, which were to destroy the superficial layers. All patients achieved excellent (n = 7, pain relief without medication) or good (n = 3, pain relief with medication) pain relief postoperatively, and the recurrence of pain was not reported in any patients (median 29 months after surgery, range 12-64 months). Nine patients (90%) achieved complete pain relief (a score of 0 or 1 on the VAS) with or without medication. No surgical site complications such as infection or CSF leakage were noted. No motor deficit was observed in any patient. A sensory deficit was observed in 2 patients and disappeared within 1 month in 1 patient. New pain at the adjacent level of DREZ lesioning was observed in 3 patients and

  8. Spinal cord stimulation-induced analgesia: electrical stimulation of dorsal column and dorsal roots attenuates dorsal horn neuronal excitability in neuropathic rats.

    PubMed

    Guan, Yun; Wacnik, Paul W; Yang, Fei; Carteret, Alene F; Chung, Chih-Yang; Meyer, Richard A; Raja, Srinivasa N

    2010-12-01

    The sites of action and cellular mechanisms by which spinal cord stimulation reduces neuropathic pain remain unclear. We examined the effect of bipolar electrical-conditioning stimulation (50 Hz, 0.2 ms, 5 min) of the dorsal column and lumbar dorsal roots on the response properties of spinal wide dynamic range (WDR) neurons in rats after L5 spinal nerve injury. The conditioning stimulation intensity was set at the lowest current that evoked a peak antidromic sciatic Aα/β-compound action potential without inducing an Aδ- or C-compound action potential. Within 15 min of the dorsal column or root conditioning stimulation, the spontaneous activity rate of WDR neurons was significantly reduced in nerve-injured rats. Conditioning stimulation also significantly attenuated WDR neuronal responses to mechanical stimuli in nerve-injured rats and inhibited the C-component of the neuronal response to graded intracutaneous electrical stimuli applied to the receptive field in nerve-injured and sham-operated rats. It is noteworthy that dorsal column stimulation blocked windup of WDR neuronal response to repetitive intracutaneous electrical stimulation (0.5 Hz) in nerve-injured and sham-operated rats, whereas dorsal root stimulation inhibited windup only in sham-operated rats. Therefore, stimulation of putative spinal substrates at A-fiber intensities with parameters similar to those used by patients with spinal cord stimulators attenuated established WDR neuronal hyperexcitability in the neuropathic condition and counteracted activity-dependent increase in neuronal excitability (i.e., windup). These results suggest a potential cellular mechanism underlying spinal cord stimulation-induced pain relief. This in vivo model allows the neurophysiologic basis for spinal cord stimulation-induced analgesia to be studied.

  9. An in vitro assay system for studying synapse formation between nociceptive dorsal root ganglion and dorsal horn neurons

    PubMed Central

    Joseph, Donald J.; Choudhury, Papiya; MacDermott, Amy B.

    2010-01-01

    Synapses between nociceptive dorsal root ganglion (DRG) neurons and spinal cord dorsal horn neurons represent the first loci for transmission of painful stimuli. Our knowledge of the molecular organization and development of these synapses is sparse due, partly, to a lack of a reliable model system that reconstitutes synaptogenesis between these two neuronal populations. To address this issue, we have established an in vitro assay system consisting of separately purified DRG neurons and dorsal horn neurons on astrocyte micro-islands. Using immunocytochemistry, we have found that 97%, 93%, 98%, 96%, and 94% of DRG neurons on these microislands express markers often associated with nociceptive neurons including Substance P, TRPV1, calcitonin-gene related peptide (CGRP), TrKA, and peripherin, respectively. Triple labeling with these nociceptive-like markers, synaptic vesicle marker Vglut2 and using MAP2 as a dendritic marker revealed the presence of nociceptive-like markers at synaptic terminals. Using this immunocytochemical approach, we counted contact points as overlapping MAP2/Vglut2 puncta and showed that they increased with time in culture. Single and dual patch clamp recordings showed that overlapping Vglut2/MAP2 puncta observed after a few days in culture are likely to be functional synapses between DRG and dorsal horn neurons in our in vitro assay system. Taken together, these data suggest our co-culture microisland model system consists of mostly nociceptive-like DRG neurons that express presynaptic markers and form functional synapses with their dorsal horn partners. Thus, this model system may have direct application for studies on factors regulating development of nociceptive DRG/dorsal horn synapses. PMID:20385165

  10. Delayed olfactory ensheathing cell transplants reduce nociception after dorsal root injury.

    PubMed

    Wu, Ann; Lauschke, Jenny L; Gorrie, Catherine A; Cameron, Nicholas; Hayward, Ian; Mackay-Sim, Alan; Waite, Phil M E

    2011-05-01

    Injury to cervical dorsal roots mimics the deafferentation component of brachial plexus injury in humans, with intractable neuropathic pain in the deafferented limb being a common consequence. Such lesions are generally not amenable to surgical repair. The use of olfactory ensheathing cells (OECs) for dorsal root repair, via acute transplantation, has been successful in several studies. From a clinical point of view, delayed transplantation of OECs would provide a more realistic timeframe for repair. In this study we investigated the effect of delayed OEC transplantation on functional recovery of skilled forepaw movements and amelioration of neuropathic pain, using a C7 and C8 dorsal root injury rat model previously established in our lab. We found that OEC transplantation to the dorsal horn 1 week after root injury effectively attenuated neuropathic disturbances associated with dorsal root injury, including spontaneous pain behavior, tactile allodynia and thermal hyperalgesia. The sensory controls of complex, goal-oriented skilled reaching and ladder walking, however, were not improved by delayed OEC transplantation. We did not detect any significant influence of transplanted OECs on injury-induced central reorganisation and afferent sprouting. The anti-nociceptive effect mediated by OEC transplants may therefore be explained by alternative mechanisms such as modification of inflammation and astrogliosis. The significant effect of OEC transplants in mitigating neuropathic pain may be clinically useful in intractable pain syndromes arising from deafferentation. This article is part of a Special Issue entitled: Understanding olfactory ensheathing glia and their prospect for nervous system repair.

  11. Dorsal root ganglion progenitors differentiate to gamma-aminobutyric acid- and choline acetyltransferase-positive neurons☆

    PubMed Central

    Yu, Lingli; Ding, Yindi; Spencer, Ambre; Ma, Ji; Lu, Ruisheng; Rudkin, Brian B.; Yuan, Chonggang

    2012-01-01

    This study examined the isolation and differentiation of dorsal root ganglion progenitor cells for therapeutic use in neurodegenerative diseases. Rat embryonic dorsal root ganglia progenitors were isolated and purified using the differential adhesion method combined with cytosine arabinoside treatment. After culture in serum-free medium supplemented with B27, basic fibroblast growth factor and epidermal growth factor, these cells remained viable and survived for more than 18 months in vitro. Most cells differentiated to neurons that were immunoreactive for gamma-aminobutyric acid and choline acetyltransferase as detected by immunohistochemical staining. In addition, nerve growth factor and neurotrophic tyrosine kinase receptor expression were also observed in dorsal root ganglion progenitors and differentiated cells. K252a, an inhibitor that blocks nerve growth factor-induced signaling, inhibited cell survival, suggesting the possible existence of a nerve growth factor autocrine loop in these proliferating cells. PMID:25745432

  12. Application of nucleus pulposus to L5 dorsal root ganglion in rats enhances nociceptive dorsal horn neuronal windup.

    PubMed

    Cuellar, J M; Montesano, P X; Antognini, J F; Carstens, E

    2005-07-01

    Herniation of the nucleus pulposus (NP) from lumbar intervertebral discs commonly results in radiculopathic pain possibly through a neuroinflammatory response. NP sensitizes dorsal horn neuronal responses, but it is unknown whether this reflects a central or peripheral sensitization. To study central sensitization, we tested if NP enhances windup--the progressive increase in the response of a nociceptive spinal neuron to repeated electrical C-fiber stimulation--a phenomenon that may partly account for temporal summation of pain. Single-unit recordings were made from wide dynamic range (WDR; n = 36) or nociceptive-specific (NS; n = 8) L5 dorsal horn neurons in 44 isoflurane-anesthetized rats. Subcutaneous electrodes delivered electrical stimuli (20 pulses, 3 times the C-fiber threshold, 0.5 ms) to the receptive field on the hindpaw. Autologous NP was harvested from a tail disc and placed onto the L5 dorsal root ganglion after recording of baseline responses (n = 22). Controls had saline applied similarly (n = 22). Electrical stimulus trains (0.1, 0.3, and 1 Hz; 5-min interstimulus interval) were repeated every 30 min for 3-6 h after each treatment. The total number of evoked spikes (summed across all 20 stimuli) to 0.1 Hz was enhanced 3 h after NP, mainly in the after-discharge (AD) period (latency > 400 ms). Total responses to 0.3 and 1.0 Hz were also enhanced at > or = 60 min after NP in both the C-fiber (100- to 400-ms latency) and AD periods, whereas the absolute windup (C-fiber + AD - 20 times the initial response) increased at > or = 90 min after treatment. In saline controls, windup was not enhanced at any time after treatment for any stimulus frequency, although there was a trend toward enhancement at 0.3 Hz. These results are consistent with NP-induced central sensitization. Mechanical responses were not significantly enhanced after saline or NP treatment. We speculate that inflammatory agents released from (or recruited by) NP affect the dorsal root

  13. Pulsed radiofrequency of lumbar dorsal root ganglion for chronic postamputation phantom pain.

    PubMed

    Imani, Farnad; Gharaei, Helen; Rezvani, Mehran

    2012-01-01

    Chronic pain following lower-limb amputation is now a well-known neuropathic, chronic-pain syndrome that usually presents as a combination of phantom and stump pain. Controlling these types of neuropathic pain is always complicated and challenging. If pharmacotherapy does not control the patient's pain, interventional procedures have to be taken. The aim of this study was to evaluate the efficacy of using pulsed radiofrequency (PRF) on the dorsal root ganglia at the L4 and L5 nerve roots to improve phantom pain. Two patients with phantom pain were selected for the study. After a positive response to segmental nerve blockade at the L4 and L5 nerve roots, PRF was performed on the L4 and L5 dorsal root ganglia. Global clinical improvement was good in one patient, with a 40% decrease in pain on the visual analogue scale (VAS) in 6 months, and moderate in the second patient, with a 30% decrease in pain scores in 4 months. PRF of the dorsal root ganglia at the L4 and L5 nerve roots may be an effective therapeutic option for patients with refractory phantom pain.

  14. Imunoreactivity of zinc transporter 7 (ZNT7) in mouse dorsal root ganglia

    USDA-ARS?s Scientific Manuscript database

    In the present study, we showed for the first time the localization of ZNT7 immunoreactivity in the mouse dorsal root ganglion (DRG) by means of immunohistochemistry and confocal laser scanning microscopy. Our results revealed that ZNT7 immunoreactivity was abundantly expressed in the nerve cells of...

  15. Dorsal horn cells connected to the lissauer tract and their relation to the dorsal root potential in the rat.

    PubMed

    Lidierth, M; Wall, P D

    1998-08-01

    We have examined the role of dorsal horn cells that respond to Lissauer tract stimulation in regulating primary afferent depolarization (PAD). PAD was monitored by recording the dorsal root potential (DRP) in the roots of the lumbar cord. Recordings were made of the discharges of Lissauer tract-responsive cells, and their discharges were correlated with the DRPs occurring spontaneously and those evoked by stimulation. Electrical microstimulation of the Lissauer tract (<10 microA; 200 micros) was used to activate the tract selectively and evoke a characteristic long-latency DRP. Cells that were excited by Lissauer tract stimulation were found in the superficial laminae of the dorsal horn. They exhibited low rates of ongoing discharge and responded to Lissauer tract stimulation typically with a burst of impulses with a latency to onset of 5.6 +/- 2.7 ms (mean +/- SD) and to termination of 13.6 +/- 4.1 ms (n = 105). Lissauer tract-responsive cells in L5 were shown to receive convergent inputs from cutaneous and muscle afferents as they responded to stimulation of the sural nerve (100%, n = 19) and the nerve to gastrocnemius (95%, n = 19). The latency of the response to sural nerve stimulation was 3.7 +/- 1.5 ms and to gastrocnemius nerve stimulation, 8.3 +/- 3.6 ms. Stimulation through a microelectrode at a depth of 1.5 mm in the sensorimotor cortex (100 microA, 200 micros) evoked a response in 17 of 31 Lissauer tract-responsive cells (55%) with a latency to onset of 21.9 +/- 2.8 ms (n = 17). Stimulation of the sural nerve, nerve to gastrocnemius or sensorimotor cortex was shown to depress the response of Lissauer tract-responsive cells to a subsequent Lissauer tract stimulus. The ongoing discharges of Lissauer tract-responsive cells were correlated to the spontaneous DRP using spike-triggered averaging. Of 123 cells analyzed in this way, 117 (95%) were shown to be correlated to the DRP. In addition, the peaks of spontaneous negative DRPs in spinally transected

  16. Efficacious Dorsal Root Ganglion Stimulation for Painful Small Fiber Neuropathy: A Case Report.

    PubMed

    Maino, Paolo; Koetsier, Eva; Kaelin-Lang, Alain; Gobbi, Claudio; Perez, Roberto

    2017-03-01

    Small fiber neuropathy is a disorder of the peripheral nerves with typical symptoms of burning, sharp, and shooting pain and sensory disturbances in the feet. Pain treatment depends principally on the underlying etiology with concurrent administration of antidepressants, anticonvulsants, opioids, and topical treatments like capsaicin and local anesthetics. However, treatments for pain relief in these patients frequently fail. We describe the first case of intractable painful small fiber neuropathy of the foot successfully treated with spinal cord stimulation of the left L5 dorsal root ganglion.A 74-year-old man presented at our clinic with severe intractable pain, dysesthesia, and allodynia of the left foot caused by idiopathic small fiber neuropathy, confirmed by skin biopsy. His pain score was 8 on a standard 0 - 10 numeric rating scale. As the pain was not satisfactorily controlled by conventional therapy, dorsal root ganglion stimulation was proposed to the patient and, after informed consent, a specifically designed percutaneous stimulation lead was placed over the left L5 dorsal root ganglion and connected to an external neurostimulator. After a positive trial of 10 days, a permanent neurostimulator was implanted. Twenty months post-implantation the patient continued to experience stimulation-induced paresthesia covering the entire pain area and reported a pain rating of 4.Results from the case report demonstrate that the dorsal root ganglion is a promising neural stimulation target to treat neuropathic pain due to intractable small fiber neuropathy. Prospective controlled studies are warranted to confirm the efficacy of this treatment as an option for the aforementioned condition.Key words: Dorsal root ganglion stimulation, small fiber neuropathy, neuropathic pain.

  17. Recurrent dorsal root potentials and motoneuron morphology in the frog spinal cord.

    PubMed

    Shupliakov, O V; Antal, M; Székely, G

    1990-09-18

    About one third of motoneurons stimulated intracellularly evoked dorsal root potentials (DRP) in the lumbar segments of the isolated and perfused frog spinal cord. Axon collaterals were found in one of the 22 motoneurons filled with HRP (horseradish peroxidase) through the stimulating electrode. In further experiments injecting individual motoneurons with cobalt, and filling the ventral roots with HRP or cobalt, the frequency of occurrence of axon collaterals was about 2% of the number of labelled motor cells. It is suggested that the presence of motor axon collaterals is not indispensable in the generation of the DRP evoked by ventral root or motor cell stimulation.

  18. Electrical interaction between antidromically stimulated frog motoneurones and dorsal root afferents: enhancement by gallamine and TEA

    PubMed Central

    Grinnell, Alan D.

    1970-01-01

    1. Electrical interactions have been studied in the isolated frog spinal cord preparation. It is found that gallamine and tetraethylammonium chloride (TEA) markedly enhance all non-cholinergic synaptic interactions, including the electrical interaction between motoneurones (VR-VRP). In addition, in the presence of either of these drugs, a short-latency interaction is seen to exist between antidromically stimulated motoneurones and dorsal root afferents (early VR-DRP). The early VR-DRP is rarely seen in the absence of gallamine or TEA. 2. The early VR-DRP is of the same short latency as the VR-VRP and fulfils the same criteria for electrical interaction: it increases in amplitude with cooling from 17-10° C, it is not blocked by a wide variety of pharmacological blocking agents, and it is suppressed by both Mg2+ and Ca2+, with no antagonism of action between the two. 3. The early VR-DRP appears as a cluster of unitary events: all-or-none spikes conducted out the dorsal root fibres. No initial graded slow potentials are seen. Often there are two peaks in the response. 4. The early VR-DRP is facilitated by a dorsal root volley, with a time course normally intermediate between that of the orthodromic ventral root potential (DR-VRP) and the dorsal root potential (DR-DRP). This orthodromic facilitation apparently is achieved by increasing invasion of motoneurone dendritic trees and depolarization of dorsal root afferents toward threshold. 5. If the same ventral root is stimulated twice, or adjacent roots stimulated at different intervals, the second early VR-DRP, like the VR-VRP, is seen to be occluded for 10-20 msec, then facilitated to supranormal amplitudes. It is concluded that motoneurone dendrites are presynaptic to both interactions. 6. Evidence is presented that gallamine and TEA act by increasing the duration of activity both in axon terminals and in antidromically invaded motoneurones. Often second or multiple spikes result. The increased duration of

  19. Antidromic discharges of dorsal root afferents and inhibition of the lumbar monosynaptic reflex in the neonatal rat.

    PubMed

    Vinay, L; Clarac, F

    1999-04-01

    The in vitro brain stem-spinal cord preparation of neonatal (0- to five-day-old) rats was used to establish whether pathways descending from the brain stem are capable of modulating synaptic transmission from primary afferents to lumbar motoneurons within the first few days after birth. We stimulated the ventral funiculus of the spinal cord at the cervical (C1-C2) level. Single-pulse stimulations evoked both excitatory and inhibitory postsynaptic potentials in ipsilateral lumbar (L2-L5) motoneurons which were recorded intracellularly. Twin-pulse stimulations evoked bursts of action potentials in ventral roots. The amplitude of the monosynaptic dorsal root-evoked excitatory postsynaptic potential decreased when a conditioning stimulation was applied to the ventral funiculus 50-300 ms prior to the stimulation of the ipsilateral dorsal root. A decreased input resistance of the motoneurons during the early part (25-100 ms after the artifact) of the ventral funiculus-evoked postsynaptic potentials could account, at least partly, for the decreased amplitude of the dorsal root-evoked response. However, the duration of the inhibition of the dorsal root-evoked excitatory postsynaptic potential was longer than that of the decrease in input resistance. Ventral funiculus stimulation evoked antidromic discharges in dorsal roots. Recordings of dorsal root potentials showed that these discharges were generated by the underlying afferent terminal depolarizations reaching firing threshold. The dorsal root discharge overlapped with most of the time-course of the ventral funiculus-evoked inhibition of the response to dorsal root stimulation, suggesting that part of this inhibition may be exerted at a presynaptic level. The number of antidromic action potentials evoked in dorsal roots by ventral funiculus stimulation increased significantly in saline solution with chloride concentration reduced to 50% of control. Bursts of action potentials disappeared when chloride was removed

  20. Regeneration of lumbar dorsal root axons into the spinal cord of adult frogs (Rana pipiens), an HRP study.

    PubMed

    Liuzzi, F J; Lasek, R J

    1985-02-22

    Lumbar dorsal roots of adult frogs were crushed or cut and reanastomosed. Following survival times of up to 75 days, the regenerating dorsal roots were recut and anterogradely injury-filled with horseradish peroxidase. This revealed that in the adult frog, regenerating axons re-enter the spinal cord. Comparison of the distribution of these axons with that of normal dorsal root axons showed that there is a partial restoration of the segmental distribution in the gray matter. However, the long ascending sensory tract of the dorsal funiculus was not restored. The dorsal funiculus was markedly gliotic and had relatively few labelled, regenerated axons. The labelled axons that were seen in the dorsal funiculus either extended longitudinally for a distance just beneath the pia, apparently in association with the glia limitans, or traversed the region to enter the dorsal gray matter. Most of the large and small diameter axons that entered the gray matter did so by passing through the region of the dorsolateral fasciculus. Within the gray matter, small diameter, regenerated axons arborized in the region of the dorsal terminal field, a region that has been shown in the normal frog to receive cutaneous afferents only. Many large diameter axons, presumably muscle afferents, arborized in the ventral terminal field, a region shown in the normal frog to receive muscle afferents exclusively. However, many of these large diameter axons had arborizations that extended to both terminal fields, thus suggesting that some abberant connections are made during dorsal root regeneration in the adult frog.

  1. [Localization of efferent sympathetic neurons and afferent neurons in dorsal root ganglia innervating the heart].

    PubMed

    Fateev, M M; Zaikina, M G

    1989-01-01

    The retrograde transport of horseradish peroxidase (HRP) has been used to study the localization and the number of neurons innervating the heart in the right stellate ganglion and accessory cervical ganglion, spinal cord and dorsal root ganglia of the cat. HRP was applied to the central cuts of anastomose of the stellate ganglion with the vagal nerve, of the vagosympathetic trunk caudal to anastomose and of the inferior cardiac nerve. HRP-labelled neurons were detected in the stellate ganglion in the regions which give off nerves, whereas in the accessory cervical ganglion labelled neurons were distributed throughout the whole ganglion. HRP-stained cells were found in the anastomose. In the spinal cord labelled neurons were detected in the lateral horn of T1-T5 segments. In the dorsal root ganglion the greatest number of neurons was observed in T2-T4 segments.

  2. TNFa/TNFR2 signaling is required for glial ensheathment at the dorsal root entry zone.

    PubMed

    Smith, Cody J; Wheeler, Michael A; Marjoram, Lindsay; Bagnat, Michel; Deppmann, Christopher D; Kucenas, Sarah

    2017-04-05

    Somatosensory information from the periphery is routed to the spinal cord through centrally-projecting sensory axons that cross into the central nervous system (CNS) via the dorsal root entry zone (DREZ). The glial cells that ensheath these axons ensure rapid propagation of this information. Despite the importance of this glial-axon arrangement, how this afferent nerve is assembled during development is unknown. Using in vivo, time-lapse imaging we show that as centrally-projecting pioneer axons from dorsal root ganglia (DRG) enter the spinal cord, they initiate expression of the cytokine TNFalpha. This induction coincides with ensheathment of these axons by associated glia via a TNF receptor 2 (TNFR2)-mediated process. This work identifies a signaling cascade that mediates peripheral glial-axon interactions and it functions to ensure that DRG afferent projections are ensheathed after pioneer axons complete their navigation, which promotes efficient somatosensory neural function.

  3. TNFa/TNFR2 signaling is required for glial ensheathment at the dorsal root entry zone

    PubMed Central

    Smith, Cody J.; Bagnat, Michel; Deppmann, Christopher D.

    2017-01-01

    Somatosensory information from the periphery is routed to the spinal cord through centrally-projecting sensory axons that cross into the central nervous system (CNS) via the dorsal root entry zone (DREZ). The glial cells that ensheath these axons ensure rapid propagation of this information. Despite the importance of this glial-axon arrangement, how this afferent nerve is assembled during development is unknown. Using in vivo, time-lapse imaging we show that as centrally-projecting pioneer axons from dorsal root ganglia (DRG) enter the spinal cord, they initiate expression of the cytokine TNFalpha. This induction coincides with ensheathment of these axons by associated glia via a TNF receptor 2 (TNFR2)-mediated process. This work identifies a signaling cascade that mediates peripheral glial-axon interactions and it functions to ensure that DRG afferent projections are ensheathed after pioneer axons complete their navigation, which promotes efficient somatosensory neural function. PMID:28379965

  4. Spontaneous resolution of an infantile hemangioma in a dorsal root ganglion.

    PubMed

    Hervey-Jumper, Shawn L; McKeever, Paul E; Gebarski, Stephen S; Muraszko, Karin M; Maher, Cormac O

    2011-12-01

    Infantile hemangiomas are tumors commonly seen in children. Few authors have reported infantile hemangiomas affecting the CNS, and there are no prior reports detailing spontaneous resolution of a histologically proven juvenile hemangioma within a dorsal root ganglion. The authors report the case of a newborn boy with a large cutaneous hemangioma in the midline of his back. Spinal MR images were obtained to rule out associated spinal cord tethering, and an intradural spinal lesion was unexpectedly discovered. Biopsy revealed an intradural infantile hemangioma within the dorsal root ganglion, and, based on this diagnosis, no resection was performed. Sixteen months following the biopsy, the cutaneous hemangioma had become involuted and the intradural hemangioma had completely resolved. The behavior of the intradural component in this case follows the natural history of many cutaneous infantile hemangiomas.

  5. Antidromic discharges in dorsal roots of decerebrate cats. I. Studies at rest and during fictive locomotion.

    PubMed

    Beloozerova, I; Rossignol, S

    1999-10-30

    Spontaneous rhythmic antidromic discharges have previously been recorded in proximal stumps of cut dorsal roots during locomotion (real and fictive). The goals of the present study were to elucidate (1) whether both orthodromic and antidromic discharges occur in the same dorsal root filament and (2) whether orthodromic discharges have an influence upon antidromic discharges of units in the same filament. Unitary activity was recorded in 70 uncut dorsal root filaments (L6-S1) in 15 decerebrate cats using bipolar Ag/AgCl electrodes. Spikes with similar wave shapes were considered to represent the activity of single units. Spike-triggered averaging (STA), local anaesthesia and transection of filaments were used to determine the direction of propagation of spikes. Spikes with different initial electrical polarities were found in most of the filaments and shown to propagate in opposite directions at rest and during fictive locomotion. On average, there were 38%+/-S.D. 23% antidromically discharging units per filament and their mean conduction velocity was 55 m/s+/-S.D. 25 m/s. After blocking orthodromic activity of the whole filament by a transection or local anesthesia applied distally to the recording site, changes were seen in the antidromic discharges of some units suggesting that spontaneous orthodromic discharges normally seen in the filament may influence the antidromic discharges of some units. Moreover, out of 27 antidromic units recorded during fictive locomotion, 12 were rhythmically modulated with peak discharges occurring in various parts of the locomotor cycle. We conclude that, in uncut dorsal roots, there is a normal coexistence of spontaneous orthodromic and antidromic discharges revealed by STA and that there is an interaction between spontaneous orthodromic and antidromic discharges.

  6. Antidromic discharges in dorsal roots of decerebrate cats. II: studies during treadmill locomotion.

    PubMed

    Beloozerova, Irina N; Rossignol, Serge

    2004-01-23

    In a previous companion paper [Brain Res. 846 (1999) 87-105] we have shown that the dorsal root activity of a decerebrate cat is composed of both orthodromic and antidromic discharges as determined by spike triggered averaging (STA). Furthermore we have shown that, during fictive locomotion in decerebrate and paralyzed cats, antidromic discharges peak in different parts of locomotion cycle but mainly in the flexion phase. In the present study, we have recorded unit potentials from dorsal rootlets during treadmill locomotion in order to understand better the role of movement-related feedback in the generation of antidromic potentials. The unitary activity of 92 antidromically discharging units was recorded in proximal stumps of cut dorsal roots, and that of 20 such units was recorded in uncut roots using two bipolar Ag/AgCl electrodes in both cases. The activity of 80% (74/92) units in cut filaments and of 70% (14/20) units in uncut ones was phasewise related to stepping movements. The peaks of activity of different units occurred during different phases of the step cycle both in cut and uncut filaments. In most cases, the peak of activity was superimposed upon a background of sustained discharge. After blocking the orthodromic flow in a filament (local anesthesia or distal section), the antidromic discharges continued to peak during the same phase but the rate of the discharges increased. We conclude that movement-related afferent feedback significantly modulates the antidromic discharges in dorsal roots during treadmill locomotion. We suggest that these antidromic discharges have a role in controlling afferent feedback during movement.

  7. Generation of New Neurons in Dorsal Root Ganglia in Adult Rats after Peripheral Nerve Crush Injury

    PubMed Central

    2015-01-01

    The evidence of neurons generated ex novo in sensory ganglia of adult animals is still debated. In the present study, we investigated, using high resolution light microscopy and stereological analysis, the changes in the number of neurons in dorsal root ganglia after 30 days from a crush lesion of the rat brachial plexus terminal branches. Results showed, as expected, a relevant hypertrophy of dorsal root ganglion neurons. In addition, we reported, for the first time in the literature, that neuronal hypertrophy was accompanied by massive neuronal hyperplasia leading to a 42% increase of the number of primary sensory neurons. Moreover, ultrastructural analyses on sensory neurons showed that there was not a relevant neuronal loss as a consequence of the nerve injury. The evidence of BrdU-immunopositive neurons and neural progenitors labeled with Ki67, nanog, nestin, and sox-2 confirmed the stereological evidence of posttraumatic neurogenesis in dorsal root ganglia. Analysis of morphological changes following axonal damage in addition to immunofluorescence characterization of cell phenotype suggested that the neuronal precursors which give rise to the newly generated neurons could be represented by satellite glial cells that actively proliferate after the lesion and are able to differentiate toward the neuronal lineage. PMID:25722894

  8. Dorsal root ganglion transcriptome analysis following peripheral nerve injury in mice

    PubMed Central

    Wu, Shaogen; Marie Lutz, Brianna; Miao, Xuerong; Liang, Lingli; Mo, Kai; Chang, Yun-Juan; Du, Peicheng; Soteropoulos, Patricia; Tian, Bin; Kaufman, Andrew G.; Bekker, Alex; Hu, Yali

    2016-01-01

    Background Peripheral nerve injury leads to changes in gene expression in primary sensory neurons of the injured dorsal root ganglia. These changes are believed to be involved in neuropathic pain genesis. Previously, these changes have been identified using gene microarrays or next generation RNA sequencing with poly-A tail selection, but these approaches cannot provide a more thorough analysis of gene expression alterations after nerve injury. Methods The present study chose to eliminate mRNA poly-A tail selection and perform strand-specific next generation RNA sequencing to analyze whole transcriptomes in the injured dorsal root ganglia following spinal nerve ligation. Quantitative real-time reverse transcriptase polymerase chain reaction assay was carried out to verify the changes of some differentially expressed RNAs in the injured dorsal root ganglia after spinal nerve ligation. Results Our results showed that more than 50 million (M) paired mapped sequences with strand information were yielded in each group (51.87 M–56.12 M in sham vs. 51.08 M–57.99 M in spinal nerve ligation). Six days after spinal nerve ligation, expression levels of 11,163 out of a total of 27,463 identified genes in the injured dorsal root ganglia significantly changed, of which 52.14% were upregulated and 47.86% downregulated. The largest transcriptional changes were observed in protein-coding genes (91.5%) followed by noncoding RNAs. Within 944 differentially expressed noncoding RNAs, the most significant changes were seen in long interspersed noncoding RNAs followed by antisense RNAs, processed transcripts, and pseudogenes. We observed a notable proportion of reads aligning to intronic regions in both groups (44.0% in sham vs. 49.6% in spinal nerve ligation). Using quantitative real-time polymerase chain reaction, we confirmed consistent differential expression of selected genes including Kcna2, Oprm1 as well as lncRNAs Gm21781 and 4732491K20Rik following spinal nerve

  9. The role of dorsal root ganglia activation and brain-derived neurotrophic factor in multiple sclerosis.

    PubMed

    Zhu, Wenjun; Frost, Emma E; Begum, Farhana; Vora, Parvez; Au, Kelvin; Gong, Yuewen; MacNeil, Brian; Pillai, Prakash; Namaka, Mike

    2012-08-01

    Multiple sclerosis (MS) is characterized by focal destruction of the white matter of the brain and spinal cord. The exact mechanisms underlying the pathophysiology of the disease are unknown. Many studies have shown that MS is predominantly an autoimmune disease with an inflammatory phase followed by a demyelinating phase. Recent studies alongside current treatment strategies, including glatiramer acetate, have revealed a potential role for brain-derived neurotrophic factor (BDNF) in MS. However, the exact role of BDNF is not fully understood. We used the experimental autoimmune encephalomyelitis (EAE) model of MS in adolescent female Lewis rats to identify the role of BDNF in disease progression. Dorsal root ganglia (DRG) and spinal cords were harvested for protein and gene expression analysis every 3 days post-disease induction (pdi) up to 15 days. We show significant increases in BDNF protein and gene expression in the DRG of EAE animals at 12 dpi, which correlates with peak neurological disability. BDNF protein expression in the spinal cord was significantly increased at 12 dpi, and maintained at 15 dpi. However, there was no significant change in mRNA levels. We show evidence for the anterograde transport of BDNF protein from the DRG to the dorsal horn of the spinal cord via the dorsal roots. Increased levels of BDNF within the DRG and spinal cord in EAE may facilitate myelin repair and neuroprotection in the CNS. The anterograde transport of DRG-derived BDNF to the spinal cord may have potential implications in facilitating central myelin repair and neuroprotection.

  10. Diversity among satellite glial cells in dorsal root ganglia of the rat.

    PubMed

    Nascimento, R S; Santiago, M F; Marques, S A; Allodi, S; Martinez, A M B

    2008-11-01

    Peripheral glial cells consist of satellite, enteric glial, and Schwann cells. In dorsal root ganglia, besides pseudo-unipolar neurons, myelinated and nonmyelinated fibers, macrophages, and fibroblasts, satellite cells also constitute the resident components. Information on satellite cells is not abundant; however, they appear to provide mechanical and metabolic support for neurons by forming an envelope surrounding their cell bodies. Although there is a heterogeneous population of neurons in the dorsal root ganglia, satellite cells have been described to be a homogeneous group of perineuronal cells. Our objective was to characterize the ultrastructure, immunohistochemistry, and histochemistry of the satellite cells of the dorsal root ganglia of 17 adult 3-4-month-old Wistar rats of both genders. Ultrastructurally, the nuclei of some satellite cells are heterochromatic, whereas others are euchromatic, which may result from different amounts of nuclear activity. We observed positive immunoreactivity for S-100 and vimentin in the cytoplasm of satellite cells. The intensity of S-100 protein varied according to the size of the enveloped neuron. We also noted that vimentin expression assumed a ring-like pattern and was preferentially located in the cytoplasm around the areas stained for S-100. In addition, we observed nitric oxide synthase-positive small-sized neurons and negative large-sized neurons equal to that described in the literature. Satellite cells were also positive for NADPH-diaphorase, particularly those associated with small-sized neurons. We conclude that all satellite cells are not identical as previously thought because they have different patterns of glial marker expression and these differences may be correlated with the size and function of the neuron they envelope.

  11. Direct injection into the dorsal root ganglion: Technical, behavioral, and histological observations

    PubMed Central

    Fischer, Gregory; Kostic, Sandra; Nakai, Hiroyuki; Park, Frank; Sapunar, Damir; Yu, Hongwei; Hogan, Quinn

    2013-01-01

    Direct injection of agents into the dorsal root ganglia (DRGs) offers the opportunity to manipulate sensory neuron function at a segmental level to explore pathophysiology of painful conditions. However, there is no described method that has been validated in detail for such injections in adult rats. We have found that 2 (µl of dye injected through a pulled glass pipette directly into the distal DRG, exposed by a minimal foraminotomy, produces complete filling of the DRG with limited extension into the spinal roots. Injection into the spinal nerve required 3 µl to achieve comparable DRG filling, produced preferential spread into the ventral root, and was accompanied by substantial leakage of injected solution from the injection site. Injections into the sciatic nerve of volumes up to 10 (µl did not reach the DRG. Transient hypersensitivity to mechanical stimulation at threshold (von Frey) and noxious levels (pin) developed after 2 µl saline injection directly into the DRG that was in part attributable to the surgical exposure procedure alone. Only minimal astrocyte activation in the spinal dorsal horn was evident after DRG saline injections. Injection of adeno-associated virus (AAV) vector conveying green fluorescent protein (GFP) transgene resulted in expression as soon as 1 day after injection into the DRG, including fibers in the spinal dorsal horn and columns. AAV injection into the DRG produced additional thermal hypersensitivity and withdrawal from the stroke of a brush and compromised motor performance. These findings demonstrate a method for selective injection of agents into single DRGs for anatomically restricted actions. PMID:21540055

  12. Gap junctional communication between the satellite cells of rat dorsal root ganglia.

    PubMed

    Sakuma, E; Wang, H J; Asai, Y; Tamaki, D; Amano, K; Mabuchi, Y; Herbert, D C; Soji, T

    2001-06-01

    Many studies have described the ultrastructure of the dorsal root ganglia in various embryonic and adult animals, but in spite of the efforts of many investigators the functional role of the satellite cells in this tissue is not clearly understood. In this study, we discuss the function of this cell type based on the concept of cell-to-cell interaction through gap junctions. Five male 60 day-old Wistar strain rats were used. All animals were anesthetized with pentobarbital and perfused with glutaraldehyde fixative, then the dorsal root ganglia in levels L4, L5 and L6 were taken from each rat. After postosmication, the specimens were prepared for observation by transmission electron microscopy. All nerve cells were completely surrounded by satellite cell cytoplasmic expansions. The boundaries between adjacent nerve cells and satellite cells were complicated due to the presence of perikaryal projections of nerve cells. Gap junctions which showed the typical trilamellar structure of plasma membranes were found mainly between satellite cell processes belonging to the same nerve cell. On the other hand, some gap junctions were found between the satellite cell projections belonging to different nerve cells. The size of the gap junctions ranged from 300 to 400 nm. No gap junctions were associated with the plasma membrane of any nerve cell. In conclusion, only satellite cells can share free transcellular exchange of cytoplasmic molecules such as ions, amino acids, sugars and several second messengers including cAMP and inositol 1,4,5-triphosphate by way of gap junctions in dorsal root ganglia.

  13. Polysensory response characteristics of dorsal root ganglion neurones that may serve sensory functions during myocardial ischaemia.

    PubMed

    Huang, M H; Horackova, M; Negoescu, R M; Wolf, S; Armour, J A

    1996-09-01

    To determine the response characteristics of dorsal root ganglion neurones that may serve sensory functions during myocardial ischaemia. Extracellular recordings were made from 54 spontaneously active and 5 normally quiescent dorsal root ganglion neurones (T2-T5) in 22 anaesthetized open-chest dogs under control conditions and during epicardial mechanical or chemical stimulation and myocardial ischaemia. The activity of 78% of spontaneously active and all quiescent neurones with left ventricular sensory fields was modified by left ventricular ischaemia. Forty-six spontaneously active neurones (85%) were polysensory with respect to mechanical and chemical stimuli. The 5 quiescent neurones responded only to chemical stimuli. Spontaneously active neurones associated with left ventricular mechanosensory endings (37 neurones) generated four different activity patterns in response to similar mechanical stimuli (high or low pressure active, high-low pressure active, high-low pressure inactive). A fifth group generated activity which was not related to chamber dynamics. Adenosine, adenosine 5'-triphosphate, substance P and bradykinin modified 72, 61, 65 and 63% of the spontaneously active neurones, respectively. Maximum local mechanical or chemical stimuli enhanced activity to similar degrees, as did ischaemia. Each ischaemia-sensitive neurone displayed unique activity patterns in response to similar mechanical or chemical stimuli. Most myocardial ischemia-sensitive dorsal root ganglion neurones associated with epicardial neurites sense mechanical and multiple chemical stimuli, a small population sensing only mechanical or chemical stimuli. Activity patterns generated by these neurones depend on their primary sensory characteristics or those of other neurones that may converge on them, as well as the type and magnitude of the stimuli that impinge upon their sensory fields, both normally and during ischaemia.

  14. Mechanical and thermal hyperalgesia and ectopic neuronal discharge after chronic compression of dorsal root ganglia.

    PubMed

    Song, X J; Hu, S J; Greenquist, K W; Zhang, J M; LaMotte, R H

    1999-12-01

    Chronic compression of the dorsal root ganglion (CCD) was produced in adult rats by implanting a stainless steel rod unilaterally into the intervertebral foramen, one rod at L(4) and another at L(5). Two additional groups of rats received either a sham surgery or an acute injury consisting of a transient compression of the ganglion. Withdrawal of the hindpaw was used as evidence of a nocifensive response to mechanical and thermal stimulation of the plantar surface. In addition, extracellular electrophysiological recordings of spontaneous discharges were obtained from dorsal root fibers of formerly compressed ganglia using an in vitro nerve-DRG-dorsal root preparation. The mean threshold force of punctate indentation and the mean threshold temperature of heating required to elicit a 50% incidence of foot withdrawal ipsilateral to the CCD were significantly lower than preoperative values throughout the 35 days of postoperative testing. The number of foot withdrawals ipsilateral to the CCD during a 20-min contact with a temperature-controlled floor was significantly increased over preoperative values throughout postoperative testing when the floor was 4 degrees C (hyperalgesia) and, to a lesser extent, when it was 30 degrees C (spontaneous pain). Stroking the foot with a cotton wisp never elicited a reflex withdrawal before surgery but did so in most rats tested ipsilateral to the CCD during the first 2 postoperative weeks. In contrast, the CCD produced no changes in responses to mechanical or thermal stimuli on the contralateral foot. The sham operation and acute injury produced no change in behavior other than slight, mechanical hyperalgesia for approximately 1 day, ipsilateral to the acute injury. Ectopic spontaneous discharges generated within the chronically compressed ganglion and, occurring in the absence of blood-borne chemicals and without an intact sympathetic nervous system, were recorded from neurons with intact, conducting, myelinated or unmyelinated

  15. Postoperative visual loss following dorsal root entry zone rhizotomy: A dreaded complication after a benign procedure

    PubMed Central

    Mishra, RK; Mahajan, C; Bindra, A; Goyal, K

    2016-01-01

    Postoperative visual loss (POVL) is a rare but grave postoperative complication. It has been mainly reported in patients undergoing cardiac and spinal surgeries. Dorsal root entry zone (DREZ) is pain relieving procedure performed in patients with refractory neuropathic pain with minimal complication rate. We present a case of unilateral POVL following DREZ rhizotomy in prone position in a patient having brachial plexus neuropathy. Exact etiology of vision loss was though not clear; hypotension, use of vasopressors and hemodilution may have led to vision loss in this patient. This case report highlights the associated risk factors for development of this hazardous complication. PMID:27833493

  16. Distribution pattern of dorsal root ganglion neurons synthesizing nitric oxide synthase in different animal species.

    PubMed

    Kolesár, Dalibor; Kolesárová, Mária; Kyselovič, Ján

    2017-04-01

    The main aim of the present review is to provide at first a short survey of the basic anatomical description of sensory ganglion neurons in relation to cell size, conduction velocity, thickness of myelin sheath, and functional classification of their processes. In addition, we have focused on discussing current knowledge about the distribution pattern of neuronal nitric oxide synthase containing sensory neurons especially in the dorsal root ganglia in different animal species; hence, there is a large controversy in relation to interpretation of the results dealing with this interesting field of research.

  17. Molecular target size of the vanilloid (capsaicin) receptor in pig dorsal root ganglia

    SciTech Connect

    Szallasi, A.; Blumberg, P.M. )

    1991-01-01

    The size of the vanilloid receptor was examined by high-energy radiation inactivation analysis of the binding of ({sup 3}H)resiniferatoxin to pig dorsal root ganglion membranes; it was found to be 270 {plus minus} 25 kDa. This value most likely represents the size of a receptor complex rather than of an individual subunit. Other ligand-gated cation channel complexes have reported molecular weights in this range, e.g. 300 kDa for the acetylcholine receptor.

  18. Autotaxin and lysophosphatidic acid1 receptor-mediated demyelination of dorsal root fibers by sciatic nerve injury and intrathecal lysophosphatidylcholine

    PubMed Central

    2010-01-01

    Background Although neuropathic pain is frequently observed in demyelinating diseases such as Guillain-Barré syndrome and multiple sclerosis, the molecular basis for the relationship between demyelination and neuropathic pain behaviors is poorly understood. Previously, we found that lysophosphatidic acid receptor (LPA1) signaling initiates sciatic nerve injury-induced neuropathic pain and demyelination. Results In the present study, we have demonstrated that sciatic nerve injury induces marked demyelination accompanied by myelin-associated glycoprotein (MAG) down-regulation and damage of Schwann cell partitioning of C-fiber-containing Remak bundles in the sciatic nerve and dorsal root, but not in the spinal nerve. Demyelination, MAG down-regulation and Remak bundle damage in the dorsal root were abolished in LPA1 receptor-deficient (Lpar1-/-) mice, but these alterations were not observed in sciatic nerve. However, LPA-induced demyelination in ex vivo experiments was observed in the sciatic nerve, spinal nerve and dorsal root, all which express LPA1 transcript and protein. Nerve injury-induced dorsal root demyelination was markedly attenuated in mice heterozygous for autotaxin (atx+/-), which converts lysophosphatidylcholine (LPC) to LPA. Although the addition of LPC to ex vivo cultures of dorsal root fibers in the presence of recombinant ATX caused potent demyelination, it had no significant effect in the absence of ATX. On the other hand, intrathecal injection of LPC caused potent dorsal root demyelination, which was markedly attenuated or abolished in atx+/- or Lpar1-/- mice. Conclusions These results suggest that LPA, which is converted from LPC by ATX, activates LPA1 receptors and induces dorsal root demyelination following nerve injury, which causes neuropathic pain. PMID:21062487

  19. Dorsal root ganglionopathy is responsible for the sensory impairment in CANVAS

    PubMed Central

    McLean, Catriona A.; Rodriguez, Michael L.; Chancellor, Andrew M.; Mossman, Stuart; Lamont, Duncan; Roberts, Leslie; Storey, Elsdon; Halmagyi, G. Michael

    2014-01-01

    Objective: To elucidate the neuropathology in cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS), a novel cerebellar ataxia comprised of the triad of cerebellar impairment, bilateral vestibular hypofunction, and a peripheral sensory deficit. Method: Brain and spinal neuropathology in 2 patients with CANVAS, together with brain and otopathology in another patient with CANVAS, were examined postmortem. Results: Spinal cord pathology demonstrated a marked dorsal root ganglionopathy with secondary tract degeneration. Cerebellar pathology showed loss of Purkinje cells, predominantly in the vermis. Conclusion: The likely underlying sensory pathology in CANVAS is loss of neurons from the dorsal root and V, VII, and VIII cranial nerve ganglia—in other words, it is a “neuronopathy” rather than a “neuropathy.” Clinically, CANVAS is a differential diagnosis for both spinocerebellar ataxia type 3 (or Machado-Joseph disease) and Friedreich ataxia. In addition, there are 6 sets of sibling pairs, implying that CANVAS is likely to be a late-onset recessive or autosomal dominant with reduced penetrance disorder, and identification of the culprit gene is currently a target of investigation. PMID:24682971

  20. Satellite glial cells in dorsal root ganglia are activated in streptozotocin-treated rodents.

    PubMed

    Hanani, Menachem; Blum, Erez; Liu, Shuangmei; Peng, Lichao; Liang, Shangdong

    2014-12-01

    Neuropathic pain is a very common complication in diabetes mellitus (DM), and treatment for it is limited. As DM is becoming a global epidemic it is important to understand and treat this problem. The mechanisms of diabetic neuropathic pain are largely obscure. Recent studies have shown that glial cells are important for a variety of neuropathic pain types, and we investigated what are the changes that satellite glial cells (SGCs) in dorsal root ganglia undergo in a DM type 1 model, induced by streptozotocin (STZ) in mice and rats. We carried out immunohistochemical studies to learn about changes in the activation marker glial fibrillary acidic protein (GFAP) in SGCs. We found that after STZ-treatment the number of neurons surrounded with GFAP-positive SGCs in dorsal root ganglia increased 4-fold in mice and 5-fold in rats. Western blotting for GFAP, which was done only on rats because of the larger size of the ganglia, showed an increase of about 2-fold in STZ-treated rats, supporting the immunohistochemical results. These results indicate for the first time that SGCs are activated in rodent models of DM1. As SGC activation appears to contribute to chronic pain, these results suggest that SGCs may participate in the generation and maintenance of diabetic neuropathic pain, and can serve as a potential therapeutic target.

  1. Structural basis of neuron-to-neuron cross-excitation in dorsal root ganglia.

    PubMed

    Shinder, V; Devor, M

    1994-09-01

    Lanthanum was used as a tracer substance to determine whether small molecules in the bulk extracellular space in dorsal root ganglia have access to the narrow cleft that separates sensory neurons from their surrounding satellite cell sheath. Results showed that lanthanum is able to diffuse into this cleft, especially when the tissue is incubated with the tracer before fixation. Lanthanum gained access to the cleft at the seam where adjacent satellite cell processes meet. There appears to be preferential access in the axon hillock-initial segment region. Large diameter light neurons, which generally support fast conducting myelinated axons and carry information about non-nociceptive sensory events, proved more likely to admit lanthanum than small diameter dark neurons, which tend to have thin myelinated and unmyelinated axons and typically carry nociceptive information. Peripheral axotomy triggered a reduction in the access of lanthanum to the neuron-satellite cell cleft. These data bear on the mechanism of non-synaptic cell-to-cell cross-excitation within dorsal root ganglia, and in particular, lend support to the hypothesis that this interaction is mediated chemically rather than electrically.

  2. Inhibition of calcium currents in cultured rat dorsal root ganglion neurones by (-)-baclofen.

    PubMed Central

    Dolphin, A. C.; Scott, R. H.

    1986-01-01

    Voltage-dependent inward calcium currents (ICa) activated in cultured rat dorsal root ganglion neurones were reversibly reduced in a dose-dependent manner by (-)-baclofen (10 microM to 100 microM). Baclofen (100 microM) reduced the calcium-dependent slow outward potassium current (IK(Ca)). This current was abolished in calcium-free medium and by 300 microM cadmium chloride. The action of baclofen on IK(Ca) was reduced when the calcium concentration in the medium was increased from 5 mM to 30 mM. The calcium independent fast transient voltage-dependent outward current (IK(Vt] was also reduced by baclofen; this effect remained present when Ca2+-free medium was used to prevent contamination by IK(Ca). 4-Aminopyridine (500 microM) reduced IK(Vt) and induced a small increase in ICa. The action of baclofen on ICa was partially antagonized by 4-aminopyridine. GABAB receptor-mediated inhibition of ICa in cultured rat dorsal root ganglion neurones involves a direct mechanism rather than resulting indirectly from an increase in the residual outward potassium currents activated by depolarization. The reduction in ICa by baclofen was variable and dependent on the amplitude of control ICa, larger currents being more resistant to the baclofen-induced inhibition. PMID:2423173

  3. MAPK Pathways Are Involved in Neuropathic Pain in Rats with Chronic Compression of the Dorsal Root Ganglion.

    PubMed

    Qu, Yu-Juan; Jia, Lei; Zhang, Xiao; Wei, Hui; Yue, Shou-Wei

    2016-01-01

    The aim of the present study was to investigate whether the MAPK pathways were involved in the mechanism of neuropathic pain in rats with chronic compression of the dorsal root ganglion. We determined the paw withdrawal mechanical threshold (PWMT) of rats before and after CCD surgery and then after p38, JNK, or ERK inhibitors administration. Western blotting, RT-PCR, and immunofluorescence of dorsal root ganglia were performed to investigate the protein and mRNA level of MAPKs and also the alternation in distributions of positive neurons in dorsal root ganglia. Intrathecal administration of MAPKs inhibitors, SB203580 (p38 inhibitor), SP600125 (JNK inhibitor), and U0126 (ERK inhibitor), resulted in a partial reduction in CCD-induced mechanical allodynia. The reduction of allodynia was associated with significant depression in the level of both MAPKs mRNA and protein expression in CCD rats and also associated with the decreased ratios of large size MAPKs positive neurons in dorsal root ganglia. In conclusion, the specific inhibitors of MAPKs contributed to the attenuation of mechanical allodynia in CCD rats and the large size MAPKs positive neurons in dorsal root ganglia were crucial.

  4. Direct communication of the spinal subarachnoid space with the rat dorsal root ganglia.

    PubMed

    Joukal, Marek; Klusáková, Ilona; Dubový, Petr

    2016-05-01

    The anatomical position of the subarachnoid space (SAS) in relation to dorsal root ganglia (DRG) and penetration of tracer from the SAS into DRG were investigated. We used intrathecal injection of methylene blue to visualize the anatomical position of the SAS in relation to DRG and immunostaining of dipeptidyl peptidase IV (DPP-IV) for detecting arachnoid limiting the SAS. Intrathecal administration of fluorescent-conjugated dextran (fluoro-emerald; FE) was used to demonstrate direct communication between the SAS and DRG. Intrathecal injection of methylene blue and DPP-IV immunostaining revealed that SAS delimited by the arachnoid was extended up to the capsule of DRG in a fold-like recess that may reach approximately half of the DRG length. The arachnoid was found in direct contact to the neuronal body-rich area in the angle between dorsal root and DRG as well as between spinal nerve roots at DRG. Particles of FE were found in the cells of DRG capsule, satellite glial cells, interstitial space, as well as in small and medium-sized neurons after intrathecal injection. Penetration of FE from the SAS into the DRG induced an immune reaction expressed by colocalization of FE and immunofluorescence indicating antigen-presenting cells (MHC-II+), activated (ED1+) and resident (ED2+) macrophages, and activation of satellite glial cells (GFAP+). Penetration of lumbar-injected FE into the cervical DRG was greater than that into the lumbar DRG after intrathecal injection of FE into the cisterna magna. Our results demonstrate direct communication between DRG and cerebrospinal fluid in the SAS that can create another pathway for possible propagation of inflammatory and signaling molecules from DRG primary affected by peripheral nerve injury into DRG of remote spinal segments. Copyright © 2016 Elsevier GmbH. All rights reserved.

  5. Topography of cutaneous mechanoreceptive neurones in dorsal root ganglia of skin-grafted frogs.

    PubMed

    Baker, R E; Corner, M A; Veltman, W A

    1978-11-01

    1. Topographical distribution patterns of dorsal root ganglion (d.r.g.) cutaneous neurones providing innervation to various body surfaces were examined in doublypithed Discoglossus pictus frogs.2. Using electrophysiological methods, sensory neurones innervating back skin were observed to predominate on the dorsal ganglionic surfaces, while belly skin neurones were most prevalent in the caudal half of the d.r.g. ventral surfaces. Flank neurones clustered in the medial half of d.r.g. ventral surfaces.3. Cutaneous neuronal distribution patterns within the d.r.g. of 180 degrees skin grafted animals were indistinguishable from those observed in control frogs.4. Sensory neurone distribution patterns were found to be altered in all animals with single skin type grafts. Projection patterns were always heaviest towards the autograft, which was on the opposite body surface (i.e. dorsally located d.r.g. sensory neurones projected to back skin on the frog's ventrum, while ventrally located neurones projected to belly skin on the frog's dorsum).5. The results are discussed in the light of several selective outgrowth mechanisms which have been proposed as a possible underlying basis for the development of misdirected wiping reflex behaviour in skin grafted anurans. The findings indicate that none of the proposed selective growth mechanisms can account adequately for the development of misdirected wiping reflexes, at least in the species studied.6. It is suggested that selective cell replacement, based upon competition among prespecified cutaneous neurones, might best account for the development of normal and misdirected wiping reflexes in frogs.

  6. Differentiation and migration of astrocytes in the spinal cord following dorsal root injury in the adult rat.

    PubMed

    Kozlova, Elena N

    2003-02-01

    Nerve fibre degeneration in the spinal cord is accompanied by astroglial proliferation. It is not known whether these cells proliferate in situ or are recruited from specific regions harbouring astroglial precursors. We found cells expressing nestin, characteristic of astroglial precursors, at the dorsal surface of the spinal cord on the operated side from 30 h after dorsal root injury. Nestin-expressing cells dispersed to deeper areas of the dorsal funiculus and dorsal horn on the operated side during the first few days after injury. Injection of bromodeoxyuridine (BrdU) 2 h before the end of the experiment, at 30 h after injury, revealed numerous BrdU-labelled, nestin-positive cells in the dorsal superficial region. In animals surviving 20 h after BrdU injection at 28 h postlesion, cells double-labelled with BrdU and nestin were also found in deeper areas. Labeling with BrdU 2 h before perfusion showed proliferation of microglia and radial astrocytes in the ventral and lateral funiculi on both sides of the spinal cord 30 h after injury. Nestin-positive cells coexpressed the calcium-binding protein Mts1, a marker for white matter astrocytes, in the dorsal funiculus, and were positive for glial fibrillary acidic protein (GFAP), but negative for Mts1 in the dorsal horn. One week after injury the level of nestin expression decreased and was undetectable after 3 months. Taken together, our data indicate that after dorsal root injury newly formed astrocytes in the degenerating white and grey matter first appear at the dorsal surface of the spinal cord from where some of them subsequently migrate ventrally, and differentiate into white- or grey-matter astrocytes.

  7. Paclitaxel causes degeneration of both central and peripheral axon branches of dorsal root ganglia in mice.

    PubMed

    Tasnim, Aniqa; Rammelkamp, Zoe; Slusher, Amy B; Wozniak, Krystyna; Slusher, Barbara S; Farah, Mohamed H

    2016-07-11

    Peripheral neuropathy is a common and dose-limiting side effect of many cancer chemotherapies. The taxane agents, including paclitaxel (Taxol(®)), are effective chemotherapeutic drugs but cause degeneration of predominantly large myelinated afferent sensory fibers of the peripheral nervous system in humans and animal models. Dorsal root ganglia (DRG) neurons are sensory neurons that have unipolar axons each with two branches: peripheral and central. While taxane agents induce degeneration of peripheral axons, whether they also cause degeneration of central nervous system axons is not clear. Using a mouse model of paclitaxel-induced neuropathy, we investigated the effects of paclitaxel on the central branches of sensory axons. We observed that in the spinal cords of paclitaxel-intoxicated mice, degenerated axons were present in the dorsal columns, where the central branches of DRG axons ascend rostrally. In the peripheral nerves, degenerated myelinated fibers were present in significantly greater numbers in distal segments than in proximal segments indicating that this model exhibits the distal-to-proximal degeneration pattern generally observed in human peripheral nerve disorders. We conclude that paclitaxel causes degeneration of both the peripheral and central branches of DRG axons, a finding that has implications for the site and mode of action of chemotherapy agents on the nervous system.

  8. Prenatal development of the rat dorsal root ganglia. A scanning electron-microscopic study.

    PubMed

    Matsuda, S; Uehara, Y

    1984-01-01

    This study describes three-dimensional aspects of the development and pseudo-unipolarization of neuroblasts and the maturation of satellite cells in prenatal rat dorsal root ganglia, using scanning electron microscopy, after removal of extracellular connective tissue components by trypsin digestion and HC1 hydrolysis. At 14 days of gestation, the vast majority of neurons are spindle-shaped or bipolar and only 3% are unipolar, while at 16 and 18 days this percentage has increased to 30% and 91%, respectively. The initial portions of the central and peripheral neuronal processes gradually approach each other and form a common initial portion. Finally, the cytoplasm of this common initial portion becomes thinner and elongates to form the stem process of the mature cell. Satellite cells are present from the beginning of the period studied, but intricate networks of branching satellite cell processes only develop after about day 17.

  9. Redox modulation of A-type K+ currents in pain-sensing dorsal root ganglion neurons.

    PubMed

    Hsieh, Chi-Pan

    2008-06-06

    Redox modulation of fast inactivation has been described in certain cloned A-type voltage-gated K(+) (Kv) channels in expressing systems, but the effects remain to be demonstrated in native neurons. In this study, we examined the effects of cysteine-specific redox agents on the A-type K(+) currents in acutely dissociated small diameter dorsal root ganglion (DRG) neurons from rats. The fast inactivation of most A-type currents was markedly removed or slowed by the oxidizing agents 2,2'-dithio-bis(5-nitropyridine) (DTBNP) and chloramine-T. Dithiothreitol, a reducing agent for the disulfide bond, restored the inactivation. These results demonstrated that native A-type K(+) channels, probably Kv1.4, could switch the roles between inactivating and non-inactivating K(+) channels via redox regulation in pain-sensing DRG neurons. The A-type channels may play a role in adjusting pain sensitivity in response to peripheral redox conditions.

  10. Calcium Influx Induced by Stimulation of ATP Receptors on Neurons Cultured from Rat Dorsal Root Ganglia.

    PubMed

    Bouvier, M. M.; Evans, M. L.; Benham, C. D.

    1991-01-01

    A combination of microspectrofluorimetry and single cell voltage-clamp was used to examine the response to ATP of cultured neurons from rat dorsal root ganglia. ATP activated an inward current and a rise in internal calcium concentration that was dependent on the external calcium concentration and on the magnitude of the ATP-induced current response. The response was not affected by prerelease of internal calcium stores with caffeine. The rise in internal calcium was increased at hyperpolarized membrane potentials as the calcium driving force was increased. These results demonstrate that the ATP-gated channels in these cells can admit a significant amount of calcium in a physiological calcium gradient. This alternative calcium entry pathway could provide an internal calcium signal that is spatially distinct to that generated by voltage-gated calcium entry.

  11. Dye coupling does not explain functional crosstalk within dorsal root ganglia.

    PubMed

    Zuriel, E; Devor, M

    2001-12-01

    Most primary sensory neurons in rat dorsal root ganglia (DRGs) are depolarized during repetitive impulse activity in neighboring neurons that share the same ganglion. We wondered whether this functional crosstalk might be mediated by a network of cytoplasmic bridges (gap junctions) between neighboring neurons and their satellite glia. Neurobiotin was injected intracellularly in whole excised DRGs. Some of the animals were intact, and others underwent transection of the ipsilateral sciatic nerve 7 to 21 days prior to injection. A total of 44 directly injected neurons were recovered histologically. There was little or no evidence of dye spread to neighboring satellite cells or neurons that would have indicated the presence of cytoplasmic bridges, certainly not enough to account for the nearly universal functional coupling that occurs among these neurons. Functional crosstalk within DRGs must therefore employ a different mechanism.

  12. Satellite glial cells in dorsal root ganglia are activated in experimental autoimmune encephalomyelitis.

    PubMed

    Warwick, Rebekah A; Ledgerwood, Craig J; Brenner, Talma; Hanani, Menachem

    2014-05-21

    Pain is a serious and common problem with patients suffering from multiple sclerosis (MS). Very little has been done to investigate the peripheral mechanisms of pain in MS. Here we used a mouse model of experimental autoimmune encephalomyelitis (EAE) to investigate the possible contribution of satellite glial cells (SGCs) to pain in MS. EAE mice had reduced pain thresholds 10 days after disease induction. We examined dorsal root ganglia and found increased expression of glial fibrillary acidic protein in SGCs, a marker of SGC activation, and increased coupling among SGCs, a known component of activated SGCs. Activated SGCs have previously been shown to contribute to pain in other classical neuropathic pain models, suggesting that pain in multiple sclerosis has a peripheral component.

  13. [Flavonoids from Diospyros kaki inhibit the adhesion between lymphocyte and dorsal root ganglion].

    PubMed

    Bei, Wei-Jian; Xu, An-Long; Li, Chu-Yuan; Cabot, Peter J; Hermanussen, Siobhan

    2009-05-01

    To investigate the effects of flavonoids from the leaves of Diospyros kaki L (FLDK) on the adhesion between the lymphocyte and the neurone. Centrifugal assay for fluorescence-bsaed cell adhesion was used to assay the adhesion between the lymphocyte and the dorsal root ganglion (DRG). The adhesion was significantly suppressed in the presence of FLDK dose-dependently at 5, 25 microg/mL concentration. FLDK was also effective to inhibit the adhesion under the challenge of ICAM-1 by 28.5% and 50.1%, respectively. Furthermore, FLDK enforced the inhibition of anti-NCAM antibody on the lymphocyte adhesion to DRG cells. FLDK might contribute to the prevention and treatment of the inflammation injury under neuron insult such as ischemia/reperfusion, neurotrauma and other neurodegenerative disease by inhibiting the adhesion between lymphocytes and neurons.

  14. The Dorsal Root Ganglion as a Therapeutic Target for Chronic Pain.

    PubMed

    Liem, Liong; van Dongen, Eric; Huygen, Frank J; Staats, Peter; Kramer, Jeff

    2016-01-01

    Chronic neuropathic pain is a widespread problem with negative personal and societal consequences. Despite considerable clinical neuroscience research, the goal of developing effective, reliable, and durable treatments has remained elusive. The critical role played by the dorsal root ganglion (DRG) in the induction and maintenance of chronic pain has been largely overlooked in these efforts, however. It may be that, by targeting this site, robust new options for pain management will be revealed. This review summarizes recent advances in the knowledge base for DRG-targeted treatments for neuropathic pain:• Pharmacological options including the chemical targeting of voltage-dependent calcium channels, transient receptor potential channels, neurotrophin production, potentiation of opioid transduction pathways, and excitatory glutamate receptors.• Ablation or modulation of the DRG via continuous thermal radiofrequency and pulsed radiofrequency treatments.• Implanted electrical neurostimulator technologies.• Interventions involving the modification of DRG cellular function at the genetic level by using viral vectors and gene silencing methods.

  15. Cross-inhibition of mechanoreceptive inputs in dorsal root ganglia of peripheral inflammatory cats.

    PubMed

    Xu, Guang-Yin; Zhao, Zhi-Qi

    2003-04-25

    Primary afferent neurons in mammalian dorsal root ganglia (DRGs) normally function as independent sensory communication elements. However, it has recently been shown that most DRG neurons are transiently activated when axons of neighboring neurons of the same ganglion are stimulated repetitively and the cross-depolarization contributes to this mutual cross-excitation. Here, we reported the cross-inhibition of mechanoreceptive information in DRG under peripheral inflammatory condition. Intracellular recordings were made in vivo from A-type afferent neurons in cat L(6-7) DRGs. Among spontaneously firing neurons both from control (Con) and carrageenan (Carg) injected cats, some A-type afferent neurons showed to have two distinct receptive fields on the hindpaw. Mechanical stimulation of one receptive field increased the ongoing activities, while stimulation of the other receptive field led to a decrease of spontaneous firings of the same neuron. These two distinct receptive fields are termed excitatory receptive field (ERF) and inhibitory receptive field (IRF), respectively. Peripheral inflammation significantly increased the prevalence of Abeta and Adelta neurons with two distinct receptive fields (Abeta: Con, 1.34%, n=149; Carg, 6.59%, n=182; P<0.05; Adelta: Con, 0%, n=138, Carg, 3.9%, n=102, P<0.05). Most interestedly, ERF stimulation-induced enhancement of cell firings can be suppressed by IRF stimulation. Similarly, IRF stimulation-induced decrease of cell discharges can be reversed by ERF stimulation. This interaction was not affected by cutting the dorsal roots at the place close to the recorded DRG. Preapplication of naloxone and yohimbine did not block the interaction. Taken together with previous reports, this intraganglionic cross-talking appears to be mediated by collision of retrograde spread of action potentials, or/and at least in part, by an activity-dependent diffusible excitatory substance released from neuronal somata and/or adjacent axons, and

  16. Local anaesthetics block hyperpolarization-activated inward current in rat small dorsal root ganglion neurones

    PubMed Central

    Bischoff, Ulrike; Bräu, Michael E; Vogel, Werner; Hempelmann, Gunter; Olschewski, Andrea

    2003-01-01

    Hyperpolarizing voltage steps evoke slowly activating inward currents in a variety of neurones and in cardiac cells. This hyperpolarization-activated inward current (Ih) is thought to play a significant role in cell excitability, firing frequency, or in setting of the resting membrane potential in these cells. We studied the effects of lidocaine, mepivacaine, QX-314 and bupivacaine as well as its enantiomers on Ih in the membrane of dorsal root ganglion neurones (DRG). The patch-clamp technique was applied to small dorsal root ganglion neurones identified in 200 μM thin slices of young rat DRGs. Under voltage-clamp conditions, the whole-cell Ih current was recorded in the presence of different concentrations of the local anaesthetics. In current-clamp mode the resting membrane potential and the voltage response of DRG neurones to injected current pulses were investigated. Ih was reversibly blocked by bupivacaine, lidocaine and mepivacaine applied externally in clinically relevant concentrations. Concentration–response curves gave half-maximum inhibiting concentrations of 55, 99 and 190 μM, respectively. Bupivacaine block of the Ih current was not stereoselective. No significant effect was observed when QX-314 was applied to the external surface of the membrane. In current-clamp experiments 60 μM bupivacaine slightly hyperpolarized the membrane. The membrane stimulation by low-amplitude current pulses in the presence of bupivacaine showed an increase of the hyperpolarizing responses. Our findings suggest an important role of the Ih-block by local anaesthetics in the complex mechanism of drug action during epidural and spinal anaesthesia. PMID:12890706

  17. Effects of peripheral nerve injury on parvalbumin expression in adult rat dorsal root ganglion neurons.

    PubMed

    Medici, Tom; Shortland, Peter J

    2015-12-16

    Parvalbumin (PV) is a calcium binding protein that identifies a subpopulation of proprioceptive dorsal root ganglion (DRG) neurons. Calcitonin gene-related peptide (CGRP) is also expressed in a high proportion of muscle afferents but its relationship to PV is unclear. Little is known of the phenotypic responses of muscle afferents to nerve injury. Sciatic nerve axotomy or L5 spinal nerve ligation and section (SNL) lesions were used to explore these issues in adult rats using immunocytochemistry. In naive animals, the mean PV expression was 25 % of L4 or L5 dorsal root ganglion (DRG) neurons, and this was unchanged 2 weeks after sciatic nerve axotomy. Colocalization studies with the injury marker activating transcription factor 3 (ATF3) showed that approximately 24 % of PV neurons expressed ATF3 after sciatic nerve axotomy suggesting that PV may show a phenotypic switch from injured to uninjured neurons. This possibility was further assessed using the spinal nerve ligation (SNL) injury model where injured and uninjured neurons are located in different DRGs. Two weeks after L5 SNL there was no change in total PV staining and essentially all L5 PV neurons expressed ATF3. Additionally, there was no increase in PV-ir in the adjacent uninjured L4 DRG cells. Co-labelling of DRG neurons revealed that less than 2 % of PV neurons normally expressed CGRP and no colocalization was seen after injury. These experiments clearly show that axotomy does not produce down regulation of PV protein in the DRG. Moreover, this lack of change is not due to a phenotypic switch in PV immunoreactive (ir) neurons, or de novo expression of PV-ir in uninjured neurons after nerve injury. These results further illustrate differences that occur when muscle afferents are injured as compared to cutaneous afferents.

  18. Sulfur dioxide derivatives modulation of high-threshold calcium currents in rat dorsal root ganglion neurons.

    PubMed

    Du, Zhengqing; Meng, Ziqiang

    2006-09-11

    This study addressed the effect of sulfur dioxide (SO(2)) derivatives on high-voltage-activated calcium currents (HVA-I(Ca)) in somatic membrane of freshly isolated rat dorsal root ganglion (DRG) neurons by using the whole-cell configuration of patch-clamp technique. High-threshold Ca(2+) channels are highly expressed in small dorsal root ganglion neurons. SO(2) derivatives increased the amplitudes of calcium currents in a concentration-dependent and voltage-dependent manner. The 50% enhancement concentrations (EC(50)) of SO(2) derivatives on HVA-I(Ca) was about 0.4 microM. In addition, SO(2) derivatives significantly shifted the activation and inactivation curve in the depolarizing direction. Parameters for the fit of a Boltzmann equation to mean values for the activation were V(1/2)=-17.9+/-1.3 mV before and -12.5+/-1.1 mV after application 0.5 microM SO(2) derivatives 2 min (P<0.05). The half inactivation of HVA-I(Ca) was shifted 9.7 mV to positive direction (P<0.05). Furthermore, SO(2) derivatives significantly prolonged the slow constant of inactivation, slowed the fast recovery but markedly accelerated the slow recovery of HVA-I(Ca) from inactivation. From HP of -60 mV 0.5 microM SO(2) derivatives increased the amplitude of HVA-I(Ca) with a depolarizing voltage step to -10 mV about 54.0% in small DRG neurons but 33.3% in large DRG neurons. These results indicated a possible correlation between the change of calcium channels and SO(2) inhalation toxicity, which might cause periphery neurons abnormal regulation of nociceptive transmission via calcium channels.

  19. Critical evaluation of the expression of gastrin-releasing peptide in dorsal root ganglia and spinal cord

    PubMed Central

    Barry, Devin M; Li, Hui; Liu, Xian-Yu; Shen, Kai-Feng; Liu, Xue-Ting; Wu, Zhen-Yu; Munanairi, Admire; Chen, Xiao-Jun; Yin, Jun; Sun, Yan-Gang; Li, Yun-Qing

    2016-01-01

    There are substantial disagreements about the expression of gastrin-releasing peptide (GRP) in sensory neurons and whether GRP antibody cross-reacts with substance P (SP). These concerns necessitate a critical revaluation of GRP expression using additional approaches. Here, we show that a widely used GRP antibody specifically recognizes GRP but not SP. In the spinal cord of mice lacking SP (Tac1 KO), the expression of not only GRP but also other peptides, notably neuropeptide Y (NPY), is significantly diminished. We detected Grp mRNA in dorsal root ganglias using reverse transcription polymerase chain reaction, in situ hybridization and RNA-seq. We demonstrated that Grp mRNA and protein are upregulated in dorsal root ganglias, but not in the spinal cord, of mice with chronic itch. Few GRP+ immunostaining signals were detected in spinal sections following dorsal rhizotomy and GRP+ cell bodies were not detected in dissociated dorsal horn neurons. Ultrastructural analysis further shows that substantially more GRPergic fibers form synaptic contacts with gastrin releasing peptide receptor-positive (GRPR+) neurons than SPergic fibers. Our comprehensive study demonstrates that a majority of GRPergic fibers are of primary afferent origin. A number of factors such as low copy number of Grp transcripts, small percentage of cells expressing Grp, and the use of an eGFP GENSAT transgenic as a surrogate for GRP protein have contributed to the controversy. Optimization of experimental procedures facilitates the specific detection of GRP expression in dorsal root ganglia neurons. PMID:27068287

  20. Use of fluorescently labelled calmodulins as tools to measure subcellular calmodulin activation in living dorsal root ganglion cells.

    PubMed

    Milikan, J M; Bolsover, S R

    2000-01-01

    We have used fluorescently labelled calmodulins to probe the activity of calmodulin in living dorsal root ganglion cells. Calmodulin labelled with the fluorophore 5-([4,6 dichlorotriazin-2yl]amino)-fluorescein (FL-CaM) does not change its fluorescence when it binds calcium, while calmodulin labelled at lysine 75 with 2-chloro-(6-(4-N,N-diethylamino-phenyl)-1,4,5-triazin-4-yl (TA-CaM), an environment-sensitive probe, increases its fluorescence when it binds calcium. We micro-injected FL-CaM or TA-CaM into rat dorsal root ganglion cells and found that both probes localise to the cell nucleus. In contrast, endogenous cellular calmodulin, in dorsal root ganglion cells as in hippocampal neurones, is predominantly cytosolic unless the neurones are depolarised, then it moves to the nucleus. FL-CaM and TA-CaM, introduced into dorsal root ganglion cells via a patch pipette, also immediately move to the nucleus, indicating that the nuclear localisation is a property of the labelled calmodulins. Although the subcellular distribution of FL-CaM and TA-CaM does not necessarily match that of endogenous calmodulin, we show that FL-CaM can be used as a control for TA-CaM when studying calmodulin activation in different cellular compartments.

  1. Increased Na+ and K+ currents in small mouse dorsal root ganglion neurons after ganglion compression.

    PubMed

    Fan, Ni; Sikand, Parul; Donnelly, David F; Ma, Chao; Lamotte, Robert H

    2011-07-01

    We investigated the effects of chronic compression (CCD) of the L3 and L4 dorsal root ganglion (DRG) on pain behavior in the mouse and on the electrophysiological properties of the small-diameter neuronal cell bodies in the intact ganglion. CCD is a model of human radicular pain produced by intraforaminal stenosis and other disorders affecting the DRG, spinal nerve, or root. On days 1, 3, 5, and 7 after the onset of compression, there was a significant decrease from preoperative values in the threshold mechanical force required to elicit a withdrawal of the foot ipsilateral to the CCD (tactile allodynia). Whole cell patch-clamp recordings were obtained, in vitro, from small-sized somata and, for the first time, in the intact DRG. Under current clamp, CCD neurons exhibited a significantly lower rheobase compared with controls. A few CCD but no control neurons exhibited spontaneous action potentials. CCD neurons showed an increase in the density of TTX-resistant and TTX-sensitive Na(+) current. CCD neurons also exhibited an enhanced density of voltage-dependent K(+) current, due to an increase in delayed rectifier K(+) current, without a change in the transient or "A" current. We conclude that CCD in the mouse produces a model of radicular pain, as we have previously demonstrated in the rat. While the role of enhanced K(+) current remains to be elucidated, we speculate that it represents a compensatory neuronal response to reduce ectopic or aberrant levels of neuronal activity produced by the injury.

  2. The Lyme disease spirochete Borrelia burgdorferi induces inflammation and apoptosis in cells from dorsal root ganglia

    PubMed Central

    2013-01-01

    Background Lyme neuroborreliosis (LNB), caused by the spirochete Borrelia burgdorferi, affects both the peripheral and the central nervous systems. Radiculitis or nerve root inflammation, which can cause pain, sensory loss, and weakness, is the most common manifestation of peripheral LNB in humans. We previously reported that rhesus monkeys infected with B. burgdorferi develop radiculitis as well as inflammation in the dorsal root ganglia (DRG), with elevated levels of neuronal and satellite glial cell apoptosis in the DRG. We hypothesized that B. burgdorferi induces inflammatory mediators in glial and neuronal cells and that this inflammatory milieu precipitates glial and neuronal apoptosis. Methods To model peripheral neuropathy in LNB we incubated normal rhesus DRG tissue explants with live B. burgdorferi ex vivo and identified immune mediators, producer cells, and verified the presence of B. burgdorferi in tissue sections by immunofluorescence staining and confocal microscopy. We also set up primary cultures of DRG cells from normal adult rhesus macaques and incubated the cultures with live B. burgdorferi. Culture supernatants were subjected to multiplex ELISA to detect immune mediators, while the cells were evaluated for apoptosis by the in situ TUNEL assay. A role for inflammation in mediating apoptosis was assessed by evaluating the above phenomena in the presence and absence of various concentrations of the anti-inflammatory drug dexamethasone. As Schwann cells ensheath the dorsal roots of the DRG, we evaluated the potential of live B. burgdorferi to induce inflammatory mediators in human Schwann cell (HSC) cultures. Results Rhesus DRG tissue explants exposed to live B. burgdorferi showed localization of CCL2 and IL-6 in sensory neurons, satellite glial cells and Schwann cells while IL-8 was seen in satellite glial cells and Schwann cells. Live B. burgdorferi induced elevated levels of IL-6, IL-8 and CCL2 in HSC and DRG cultures and apoptosis of sensory

  3. Expression of Semaphorins, Neuropilins, VEGF, and Tenascins in Rat and Human Primary Sensory Neurons after a Dorsal Root Injury

    PubMed Central

    Lindholm, Tomas; Risling, Mårten; Carlstedt, Thomas; Hammarberg, Henrik; Wallquist, Wilhelm; Cullheim, Staffan; Sköld, Mattias K.

    2017-01-01

    Dorsal root injury is a situation not expected to be followed by a strong regenerative growth, or growth of the injured axon into the central nervous system of the spinal cord, if the central axon of the dorsal root is injured but of strong regeneration if subjected to injury to the peripherally projecting axons. The clinical consequence of axonal injury is loss of sensation and may also lead to neuropathic pain. In this study, we have used in situ hybridization to examine the distribution of mRNAs for the neural guidance molecules semaphorin 3A (SEMA3A), semaphorin 3F (SEMA3F), and semaphorin 4F (SEMA4F), their receptors neuropilin 1 (NP1) and neuropilin 2 (NP2) but also for the neuropilin ligand vascular endothelial growth factor (VEGF) and Tenascin J1, an extracellular matrix molecule involved in axonal guidance, in rat dorsal root ganglia (DRG) after a unilateral dorsal rhizotomy (DRT) or sciatic nerve transcetion (SNT). The studied survival times were 1–365 days. The different forms of mRNAs were unevenly distributed between the different size classes of sensory nerve cells. The results show that mRNA for SEMA3A was diminished after trauma to the sensory nerve roots in rats. The SEMA3A receptor NP1, and SEMA3F receptor NP2, was significantly upregulated in the DRG neurons after DRT and SNT. SEMA4F was upregulated after a SNT. The expression of mRNA for VEGF in DRG neurons after DRT showed a significant upregulation that was high even a year after the injuries. These data suggest a role for the semaphorins, neuropilins, VEGF, and J1 in the reactions after dorsal root lesions. PMID:28270793

  4. Neuroimmune and Neuropathic Responses of Spinal Cord and Dorsal Root Ganglia in Middle Age

    PubMed Central

    Galbavy, William; Kaczocha, Martin; Puopolo, Michelino; Liu, Lixin; Rebecchi, Mario J.

    2015-01-01

    Prior studies of aging and neuropathic injury have focused on senescent animals compared to young adults, while changes in middle age, particularly in the dorsal root ganglia (DRG), have remained largely unexplored. 14 neuroimmune mRNA markers, previously associated with peripheral nerve injury, were measured in multiplex assays of lumbar spinal cord (LSC), and DRG from young and middle-aged (3, 17 month) naïve rats, or from rats subjected to chronic constriction injury (CCI) of the sciatic nerve (after 7 days), or from aged-matched sham controls. Results showed that CD2, CD3e, CD68, CD45, TNF-α, IL6, CCL2, ATF3 and TGFβ1 mRNA levels were substantially elevated in LSC from naïve middle-aged animals compared to young adults. Similarly, LSC samples from older sham animals showed increased levels of T-cell and microglial/macrophage markers. CCI induced further increases in CCL2, and IL6, and elevated ATF3 mRNA levels in LSC of young and middle-aged adults. Immunofluorescence images of dorsal horn microglia from middle-aged naïve or sham rats were typically hypertrophic with mostly thickened, de-ramified processes, similar to microglia following CCI. Unlike the spinal cord, marker expression profiles in naïve DRG were unchanged across age (except increased ATF3); whereas, levels of GFAP protein, localized to satellite glia, were highly elevated in middle age, but independent of nerve injury. Most neuroimmune markers were elevated in DRG following CCI in young adults, yet middle-aged animals showed little response to injury. No age-related changes in nociception (heat, cold, mechanical) were observed in naïve adults, or at days 3 or 7 post-CCI. The patterns of marker expression and microglial morphologies in healthy middle age are consistent with development of a para-inflammatory state involving microglial activation and T-cell marker elevation in the dorsal horn, and neuronal stress and satellite cell activation in the DRG. These changes, however, did not

  5. Neuroimmune and Neuropathic Responses of Spinal Cord and Dorsal Root Ganglia in Middle Age.

    PubMed

    Galbavy, William; Kaczocha, Martin; Puopolo, Michelino; Liu, Lixin; Rebecchi, Mario J

    2015-01-01

    Prior studies of aging and neuropathic injury have focused on senescent animals compared to young adults, while changes in middle age, particularly in the dorsal root ganglia (DRG), have remained largely unexplored. 14 neuroimmune mRNA markers, previously associated with peripheral nerve injury, were measured in multiplex assays of lumbar spinal cord (LSC), and DRG from young and middle-aged (3, 17 month) naïve rats, or from rats subjected to chronic constriction injury (CCI) of the sciatic nerve (after 7 days), or from aged-matched sham controls. Results showed that CD2, CD3e, CD68, CD45, TNF-α, IL6, CCL2, ATF3 and TGFβ1 mRNA levels were substantially elevated in LSC from naïve middle-aged animals compared to young adults. Similarly, LSC samples from older sham animals showed increased levels of T-cell and microglial/macrophage markers. CCI induced further increases in CCL2, and IL6, and elevated ATF3 mRNA levels in LSC of young and middle-aged adults. Immunofluorescence images of dorsal horn microglia from middle-aged naïve or sham rats were typically hypertrophic with mostly thickened, de-ramified processes, similar to microglia following CCI. Unlike the spinal cord, marker expression profiles in naïve DRG were unchanged across age (except increased ATF3); whereas, levels of GFAP protein, localized to satellite glia, were highly elevated in middle age, but independent of nerve injury. Most neuroimmune markers were elevated in DRG following CCI in young adults, yet middle-aged animals showed little response to injury. No age-related changes in nociception (heat, cold, mechanical) were observed in naïve adults, or at days 3 or 7 post-CCI. The patterns of marker expression and microglial morphologies in healthy middle age are consistent with development of a para-inflammatory state involving microglial activation and T-cell marker elevation in the dorsal horn, and neuronal stress and satellite cell activation in the DRG. These changes, however, did not

  6. Human Embryonic Stem Cell-Derived Progenitors Assist Functional Sensory Axon Regeneration after Dorsal Root Avulsion Injury

    PubMed Central

    Hoeber, Jan; Trolle, Carl; Konig, Niclas; Du, Zhongwei; Gallo, Alessandro; Hermans, Emmanuel; Aldskogius, Hakan; Shortland, Peter; Zhang, Su-Chun; Deumens, Ronald; Kozlova, Elena N.

    2015-01-01

    Dorsal root avulsion results in permanent impairment of sensory functions due to disconnection between the peripheral and central nervous system. Improved strategies are therefore needed to reconnect injured sensory neurons with their spinal cord targets in order to achieve functional repair after brachial and lumbosacral plexus avulsion injuries. Here, we show that sensory functions can be restored in the adult mouse if avulsed sensory fibers are bridged with the spinal cord by human neural progenitor (hNP) transplants. Responses to peripheral mechanical sensory stimulation were significantly improved in transplanted animals. Transganglionic tracing showed host sensory axons only in the spinal cord dorsal horn of treated animals. Immunohistochemical analysis confirmed that sensory fibers had grown through the bridge and showed robust survival and differentiation of the transplants. Section of the repaired dorsal roots distal to the transplant completely abolished the behavioral improvement. This demonstrates that hNP transplants promote recovery of sensorimotor functions after dorsal root avulsion, and that these effects are mediated by spinal ingrowth of host sensory axons. These results provide a rationale for the development of novel stem cell-based strategies for functionally useful bridging of the peripheral and central nervous system. PMID:26053681

  7. Pulsed Radiofrequency to the Dorsal Root Ganglion in Acute Herpes Zoster and Postherpetic Neuralgia.

    PubMed

    Kim, Koohyun; Jo, Daehyun; Kim, EungDon

    2017-03-01

    Latent varicella zoster virus reactivates mainly in sensory ganglia such as the dorsal root ganglion (DRG) or trigeminal ganglion. The DRG contains many receptor channels and is an important region for pain signal transduction. Sustained abnormal electrical activity to the spinal cord via the DRG in acute herpes zoster can result in neuropathic conditions such as postherpetic neuralgia (PHN). Although the efficacy of pulsed radiofrequency (PRF) application to the DRG in various pain conditions has been previously reported, the application of PRF to the DRG in patients with herpes zoster has not yet been studied. The aim of the present study was to compare the clinical effects of PRF to the DRG in patients with herpes zoster to those of PRF to the DRG in patients with PHN. Retrospective comparative study. University hospital pain center in Korea. The medical records of 58 patients who underwent PRF to the DRG due to zoster related pain (herpes zoster or PHN) were retrospectively analyzed. Patients were divided into 2 groups according to the timing of PRF after zoster onset: an early PRF group (within 90 days) and a PHN PRF group (more than 90 days). The efficacy of PRF was assessed by a numeric rating scale (NRS) and by recording patient medication doses before PRF and at one week, 4 weeks, 8 weeks, and 12 weeks after PRF. Pain intensity was decreased after PRF in all participants. However, the degree of pain reduction was significantly higher in the early PRF group. Moreover, more patients discontinued their medication in the early PRF group, and the PRF success rate was also higher in the early PRF group. The relatively small sample size from a single center, short duration of review of medical records, and the retrospective nature of the study. PRF to the DRG is a useful treatment for treatment-resistant cases of herpes zoster and PHN. Particularly in herpes zoster patients with intractable pain, application of PRF to the DRG should be considered for pain control

  8. Effect of low level laser therapy on chronic compression of the dorsal root ganglion.

    PubMed

    Chen, Yi-Jen; Wang, Yan-Hsiung; Wang, Chau-Zen; Ho, Mei-Ling; Kuo, Po-Lin; Huang, Mao-Hsiung; Chen, Chia-Hsin

    2014-01-01

    Dorsal root ganglia (DRG) are vulnerable to physical injury of the intervertebral foramen, and chronic compression of the DRG (CCD) an result in nerve root damage with persistent morbidity. The purpose of this study was to evaluate the effects of low level laser therapy (LLLT) on the DRG in a CCD model and to determine the mechanisms underlying these effects. CCD rats had L-shaped stainless-steel rods inserted into the fourth and fifth lumbar intervertebral foramen, and the rats were then subjected to 0 or 8 J/cm2 LLLT for 8 consecutive days following CCD surgery. Pain and heat stimuli were applied to test for hyperalgesia following CCD. The levels of TNF-α, IL-1β and growth-associated protein-43 (GAP-43) messenger RNA (mRNA) expression were measured via real-time PCR, and protein expression levels were analyzed through immunohistochemical analyses. Our data indicate that LLLT significantly decreased the tolerable sensitivity to pain and heat stimuli in the CCD groups. The expression levels of the pro-inflammatory cytokines TNF-α and IL-1β were increased following CCD, and we found that these increases could be reduced by the application of LLLT. Furthermore, the expression of GAP-43 was enhanced by LLLT. In conclusion, LLLT was able to enhance neural regeneration in rats following CCD and improve rat ambulatory behavior. The therapeutic effects of LLLT on the DRG during CCD may be exerted through suppression of the inflammatory response and induction of neuronal repair genes. These results suggest potential clinical applications for LLLT in the treatment of compression-induced neuronal disorders.

  9. Glutaminase Increases in Rat Dorsal Root Ganglion Neurons after Unilateral Adjuvant-Induced Hind Paw Inflammation.

    PubMed

    Hoffman, E Matthew; Zhang, Zijia; Schechter, Ruben; Miller, Kenneth E

    2016-01-13

    Glutamate is a neurotransmitter used at both the peripheral and central terminals of nociceptive primary sensory neurons, yet little is known concerning regulation of glutamate metabolism during peripheral inflammation. Glutaminase (GLS) is an enzyme of the glutamate-glutamine cycle that converts glutamine into glutamate for neurotransmission and is implicated in producing elevated levels of glutamate in central and peripheral terminals. A potential mechanism for increased levels of glutamate is an elevation in GLS expression. We assessed GLS expression after unilateral hind paw inflammation by measuring GLS immunoreactivity (ir) with quantitative image analysis of L4 dorsal root ganglion (DRG) neurons after one, two, four, and eight days of adjuvant-induced arthritis (AIA) compared to saline injected controls. No significant elevation in GLS-ir occurred in the DRG ipsilateral to the inflamed hind paw after one or two days of AIA. After four days AIA, GLS-ir was elevated significantly in all sizes of DRG neurons. After eight days AIA, GLS-ir remained elevated in small (<400 µm²), presumably nociceptive neurons. Western blot analysis of the L4 DRG at day four AIA confirmed the elevated GLS-ir. The present study indicates that GLS expression is increased in the chronic stage of inflammation and may be a target for chronic pain therapy.

  10. Glutaminase Increases in Rat Dorsal Root Ganglion Neurons after Unilateral Adjuvant-Induced Hind Paw Inflammation

    PubMed Central

    Hoffman, E. Matthew; Zhang, Zijia; Schechter, Ruben; Miller, Kenneth E.

    2016-01-01

    Glutamate is a neurotransmitter used at both the peripheral and central terminals of nociceptive primary sensory neurons, yet little is known concerning regulation of glutamate metabolism during peripheral inflammation. Glutaminase (GLS) is an enzyme of the glutamate-glutamine cycle that converts glutamine into glutamate for neurotransmission and is implicated in producing elevated levels of glutamate in central and peripheral terminals. A potential mechanism for increased levels of glutamate is an elevation in GLS expression. We assessed GLS expression after unilateral hind paw inflammation by measuring GLS immunoreactivity (ir) with quantitative image analysis of L4 dorsal root ganglion (DRG) neurons after one, two, four, and eight days of adjuvant-induced arthritis (AIA) compared to saline injected controls. No significant elevation in GLS-ir occurred in the DRG ipsilateral to the inflamed hind paw after one or two days of AIA. After four days AIA, GLS-ir was elevated significantly in all sizes of DRG neurons. After eight days AIA, GLS-ir remained elevated in small (<400 µm2), presumably nociceptive neurons. Western blot analysis of the L4 DRG at day four AIA confirmed the elevated GLS-ir. The present study indicates that GLS expression is increased in the chronic stage of inflammation and may be a target for chronic pain therapy. PMID:26771651

  11. Differentiation of mouse induced pluripotent stem cells into neurons using conditioned medium of dorsal root ganglia.

    PubMed

    Kitazawa, Ayako; Shimizu, Norio

    2011-07-01

    Mouse induced pluripotent stem (iPS) cells are known to have the ability to differentiate into various cell lineages including neurons in vitro. We have reported that chick dorsal root ganglion (DRG)-conditioned medium (CM) promoted the differentiation of mouse embryonic stem (ES) cells into motor neurons. We investigated the formation of undifferentiated iPS cell colonies and the differentiation of iPS cells into neurons using DRG-CM. When iPS cells were cultured in DMEM containing leukemia inhibitory factor (LIF), the iPS cells appeared to be maintained in an undifferentiated state for 19 passages. The number of iPS cell colonies (200 μm in diameter) was maximal at six days of cultivation and the colonies were maintained in an undifferentiated state, but the iPS cell colonies at ten days of cultivation had hollows inside the colonies and were differentiated. By contrast, the number of ES cell colonies (200 μm in diameter) was maximal at ten days of cultivation. The iPS cells were able to proliferate and differentiate easily into various cell lineages, compared to ES cells. When iPS cell colonies were cultured in a manner similar to ES cells with DMEM/F-12K medium supplemented with DRG-CM, the iPS cells mainly differentiated into motor and sensory neurons. These results suggested that the differentiation properties of iPS cells differ from those of ES cells.

  12. Veratridine produces distinct calcium response profiles in mouse Dorsal Root Ganglia neurons

    PubMed Central

    Mohammed, Zainab A.; Doran, Ciara; Grundy, David; Nassar, Mohammed A.

    2017-01-01

    Nociceptors are a subpopulation of dorsal root ganglia (DRG) neurons that detect noxious stimuli and signal pain. Veratridine (VTD) is a voltage-gated sodium channel (VGSC) modifier that is used as an “agonist” in functional screens for VGSC blockers. However, there is very little information on VTD response profiles in DRG neurons and how they relate to neuronal subtypes. Here we characterised VTD-induced calcium responses in cultured mouse DRG neurons. Our data shows that the heterogeneity of VTD responses reflects distinct subpopulations of sensory neurons. About 70% of DRG neurons respond to 30–100 μM VTD. We classified VTD responses into four profiles based upon their response shape. VTD response profiles differed in their frequency of occurrence and correlated with neuronal size. Furthermore, VTD response profiles correlated with responses to the algesic markers capsaicin, AITC and α, β-methylene ATP. Since VTD response profiles integrate the action of several classes of ion channels and exchangers, they could act as functional “reporters” for the constellation of ion channels/exchangers expressed in each sensory neuron. Therefore our findings are relevant to studies and screens using VTD to activate DRG neurons. PMID:28338073

  13. Chronic monitoring of lower urinary tract activity via a sacral dorsal root ganglia interface

    NASA Astrophysics Data System (ADS)

    Khurram, Abeer; Ross, Shani E.; Sperry, Zachariah J.; Ouyang, Aileen; Stephan, Christopher; Jiman, Ahmad A.; Bruns, Tim M.

    2017-06-01

    Objective. Our goal is to develop an interface that integrates chronic monitoring of lower urinary tract (LUT) activity with stimulation of peripheral pathways. Approach. Penetrating microelectrodes were implanted in sacral dorsal root ganglia (DRG) of adult male felines. Peripheral electrodes were placed on or in the pudendal nerve, bladder neck and near the external urethral sphincter. Supra-pubic bladder catheters were implanted for saline infusion and pressure monitoring. Electrode and catheter leads were enclosed in an external housing on the back. Neural signals from microelectrodes and bladder pressure of sedated or awake-behaving felines were recorded under various test conditions in weekly sessions. Electrodes were also stimulated to drive activity. Main results. LUT single- and multi-unit activity was recorded for 4-11 weeks in four felines. As many as 18 unique bladder pressure single-units were identified in each experiment. Some channels consistently recorded bladder afferent activity for up to 41 d, and we tracked individual single-units for up to 23 d continuously. Distension-evoked and stimulation-driven (DRG and pudendal) bladder emptying was observed, during which LUT sensory activity was recorded. Significance. This chronic implant animal model allows for behavioral studies of LUT neurophysiology and will allow for continued development of a closed-loop neuroprosthesis for bladder control.

  14. Artemin promotes functional long-distance axonal regeneration to the brainstem after dorsal root crush.

    PubMed

    Wong, Laura Elisabeth; Gibson, Molly E; Arnold, H Moore; Pepinsky, Blake; Frank, Eric

    2015-05-12

    Recovery after a spinal cord injury often requires that axons restore synaptic connectivity with denervated targets several centimeters from the site of injury. Here we report that systemic artemin (ARTN) treatment promotes the regeneration of sensory axons to the brainstem after brachial dorsal root crush in adult rats. ARTN not only stimulates robust regeneration of large, myelinated sensory axons to the brainstem, but also promotes functional reinnervation of the appropriate target region, the cuneate nucleus. ARTN signals primarily through the RET tyrosine kinase, an interaction that requires the nonsignaling coreceptor GDNF family receptor (GFRα3). Previous studies reported limited GFRα3 expression on large sensory neurons, but our findings demonstrate that ARTN promotes robust regeneration of large, myelinated sensory afferents. Using a cell sorting technique, we demonstrate that GFRα3 expression is similar in myelinated and unmyelinated adult sensory neurons, suggesting that ARTN likely induces long-distance regeneration by binding GFRα3 and RET. Although ARTN is delivered for just 2 wk, regeneration to the brainstem requires more than 3 mo, suggesting that brief trophic support may initiate intrinsic growth programs that remain active until targets are reached. Given its ability to promote targeted functional regeneration to the brainstem, ARTN may represent a promising therapy for restoring sensory function after spinal cord injury.

  15. Immortalized human dorsal root ganglion cells differentiate into neurons with nociceptive properties.

    PubMed

    Raymon, H K; Thode, S; Zhou, J; Friedman, G C; Pardinas, J R; Barrere, C; Johnson, R M; Sah, D W

    1999-07-01

    A renewable source of human sensory neurons would greatly facilitate basic research and drug development. We had established previously conditionally immortalized human CNS cell lines that can differentiate into functional neurons (). We report here the development of an immortalized human dorsal root ganglion (DRG) clonal cell line, HD10.6, with a tetracycline-regulatable v-myc oncogene. In the proliferative condition, HD10.6 cells have a doubling time of 1.2 d and exhibit a neuronal precursor morphology. After differentiation of clone HD10.6 for 7 d in the presence of tetracycline, v-myc expression was suppressed, and >50% of the cells exhibited typical neuronal morphology, stained positively for neuronal cytoskeletal markers, and fired action potentials in response to current injection. Furthermore, this cell line was fate-restricted to a neuronal phenotype; even in culture conditions that promote Schwann cell or smooth muscle differentiation of neural crest stem cells, HD10.6 differentiated exclusively into neurons. Moreover, differentiated HD10.6 cells expressed sensory neuron-associated transcription factors and exhibited capsaicin sensitivity. Taken together, these data indicate that we have established an immortalized human DRG cell line that can differentiate into sensory neurons with nociceptive properties. The cell line HD10.6 represents the first example of a human sensory neuronal line and will be valuable for basic research, as well as for the discovery of novel drug targets and clinical candidates.

  16. Neuroprotective effects of resveratrol on embryonic dorsal root ganglion neurons with neurotoxicity induced by ethanol.

    PubMed

    Yuan, Hongtu; Zhang, Weiwei; Li, Hao; Chen, Cheng; Liu, Huaxiang; Li, Zhenzhong

    2013-05-01

    Studies have established that ethanol (EtOH) consumption results in damage to the peripheral nervous systems. Although the pathobiological mechanism is still unclear, oxidative stress is known to play an important role in EtOH-induced neurotoxicity. Because resveratrol (Res) is attracting increased attention due to its antioxidative properties, we investigated the neuroprotective efficacy of Res in ethanol-treated embryonic dorsal root ganglion (DRG) neurons in vitro. Organotypic DRG explants and a dispersed cell culture model were used to evaluate the effects of Res on EtOH-induced neurotoxicity. Res increased the number of extended nerve fibers and neurons that migrated from the DRG explants. Hoechst 33342 staining and terminal deoxynucleotidyl-transferase-mediated dUTP nick-end-labeling analysis showed that the EtOH-induced apoptosis was inhibited by Res. The effects of Res were blocked by the 5'-adenosine monophosphate-activated protein kinase inhibitor Compound C and the sirtuin 1 inhibitor nicotinamide. The elevation of oxidative/nitrosative stress, as measured by the amount of reactive oxygen species, malondialdehyde, nitrite, glutathione and superoxide dismutase activity, was also attenuated by Res. The data from the present study indicate that Res protects DRG neurons from EtOH-induced neurotoxicity. Res and its derivative may be effective for the treatment of diseases characterized by axonopathy and neuron loss induced by EtOH. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. CPEB3 Deficiency Elevates TRPV1 Expression in Dorsal Root Ganglia Neurons to Potentiate Thermosensation

    PubMed Central

    Chen, Chih-Cheng; Huang, Yi-Shuian

    2016-01-01

    Cytoplasmic polyadenylation element binding protein 3 (CPEB3) is a sequence-specific RNA-binding protein that downregulates translation of multiple plasticity-related proteins (PRPs) at the glutamatergic synapses. Activity-induced synthesis of PRPs maintains long-lasting synaptic changes that are critical for memory consolidation and chronic pain manifestation. CPEB3-knockout (KO) mice show aberrant hippocampus-related plasticity and memory, so we investigated whether CPEB3 might have a role in nociception-associated plasticity. CPEB3 is widely expressed in the brain and peripheral afferent sensory neurons. CPEB3-KO mice with normal mechanosensation showed hypersensitivity to noxious heat. In the complete Freund's adjuvant (CFA)-induced inflammatory pain model, CPEB3-KO animals showed normal thermal hyperalgesia and transiently enhanced mechanical hyperalgesia. Translation of transient receptor potential vanilloid 1 (TRPV1) RNA was suppressed by CPEB3 in dorsal root ganglia (DRG), whereas CFA-induced inflammation reversed this inhibition. Moreover, CPEB3/TRPV1 double-KO mice behaved like TRPV1-KO mice, with severely impaired thermosensation and thermal hyperalgesia. An enhanced thermal response was recapitulated in non-inflamed but not inflamed conditional-KO mice, with cpeb3 gene ablated mostly but not completely, in small-diameter nociceptive DRG neurons. CPEB3-regulated translation of TRPV1 RNA may play a role in fine-tuning thermal sensitivity of nociceptors. PMID:26915043

  18. Patch Clamp Recordings on Intact Dorsal Root Ganglia from Adult Rats.

    PubMed

    Gong, Kerui; Ohara, Peter T; Jasmin, Luc

    2016-09-29

    Patch clamp studies from dorsal root ganglia (DRGs) neurons have increased our understanding of the peripheral nervous system. Currently, the majority of recordings are conducted on dissociated DRG neurons, which is a standard preparation for most laboratories. Neuronal properties, however, can be altered by axonal injury resulting from enzyme digestion used in acquiring dissociated neurons. Further, dissociated neuron preparations cannot fully represent the microenvironment of the DRG since loss of contact with satellite glial cells that surround the primary sensory neurons is an unavoidable consequence of this method. To overcome the limitations in using conventional dissociated DRG neurons for patch clamp recordings, in this report we describe a method to prepare intact DRGs and conduct patch clamp recordings on individual primary sensory neurons ex vivo. This approach permits the fast and straightforward preparation of intact DRGs, mimicking in vivo conditions by keeping DRG neurons associated with their surrounding satellite glial cells and basement membrane. Furthermore, the method avoids axonal injury from manipulation and enzyme digestion such as when dissociating DRGs. This ex vivo preparation can additionally be used to study the interaction between primary sensory neurons and satellite glial cells.

  19. Real-time control of walking using recordings from dorsal root ganglia

    NASA Astrophysics Data System (ADS)

    Holinski, B. J.; Everaert, D. G.; Mushahwar, V. K.; Stein, R. B.

    2013-10-01

    Objective. The goal of this study was to decode sensory information from the dorsal root ganglia (DRG) in real time, and to use this information to adapt the control of unilateral stepping with a state-based control algorithm consisting of both feed-forward and feedback components. Approach. In five anesthetized cats, hind limb stepping on a walkway or treadmill was produced by patterned electrical stimulation of the spinal cord through implanted microwire arrays, while neuronal activity was recorded from the DRG. Different parameters, including distance and tilt of the vector between hip and limb endpoint, integrated gyroscope and ground reaction force were modelled from recorded neural firing rates. These models were then used for closed-loop feedback. Main results. Overall, firing-rate-based predictions of kinematic sensors (limb endpoint, integrated gyroscope) were the most accurate with variance accounted for >60% on average. Force prediction had the lowest prediction accuracy (48 ± 13%) but produced the greatest percentage of successful rule activations (96.3%) for stepping under closed-loop feedback control. The prediction of all sensor modalities degraded over time, with the exception of tilt. Significance. Sensory feedback from moving limbs would be a desirable component of any neuroprosthetic device designed to restore walking in people after a spinal cord injury. This study provides a proof-of-principle that real-time feedback from the DRG is possible and could form part of a fully implantable neuroprosthetic device with further development.

  20. Inhibition of acid-sensing ion channels by chlorogenic acid in rat dorsal root ganglion neurons.

    PubMed

    Qu, Zu-Wei; Liu, Ting-Ting; Qiu, Chun-Yu; Li, Jia-Da; Hu, Wang-Ping

    2014-05-01

    Chlorogenic acid (CGA) is one of the most abundant polyphenol compounds in the human diet. Recently, it is demonstrated to have potent antinociceptive effect. However, little is understood about the mechanism underlying CGA analgesia. Here, we have found that CGA can exert an inhibitory effect on the functional activity of native acid-sensing ion channels (ASICs) in rat dorsal root ganglion (DRG) neurons. First, CGA decreased the peak amplitude of proton-gated currents mediated by ASICs in a concentration-dependent manner. Second, CGA shifted the proton concentration-response curve downward, with a decrease of 41.76 ± 8.65% in the maximum current response to protons but with no significant change in the pH0.5 value. Third, CGA altered acidosis-evoked membrane excitability of rat DRG neurons and caused a significant decrease in the amplitude of the depolarization and the number of action potentials induced by acid stimuli. Finally, peripheral administered CGA attenuated nociceptive response to intraplantar injection of acetic acid in rats. ASICs are distributed in peripheral sensory neurons and participate in nociception. Our findings CGA inhibition of native ASICs indicated that CGA may exert analgesic action by modulating ASICs in the primary afferent neurons, which revealed a novel cellular and molecular mechanism underlying CGA analgesia.

  1. Sodium metabisulfite modulation of potassium channels in pain-sensing dorsal root ganglion neurons.

    PubMed

    Nie, Aifang; Wei, Cailing; Meng, Ziqiang

    2009-12-01

    The effects of sodium metabisulfite (SMB), a general food preservative, on potassium currents in rat dorsal root ganglion (DRG) neurons were investigated using the whole-cell patch-clamp technique. SMB increased the amplitudes of both transient outward potassium currents and delayed rectifier potassium current in concentration- and voltage-dependent manner. The transient outward potassium currents (TOCs) include a fast inactivating (A-current or IA) current and a slow inactivating (D-current or ID) current. SMB majorly increased IA, and ID was little affected. SMB did not affect the activation process of transient outward currents (TOCs), but the inactivation curve of TOCs was shifted to more positive potentials. The inactivation time constants of TOCs were also increased by SMB. For delayed rectifier potassium current (IK), SMB shifted the activation curve to hyperpolarizing direction. SMB differently affected TOCs and IK, its effects major on A-type K+ channels, which play a role in adjusting pain sensitivity in response to peripheral redox conditions. SMB did not increase TOCs and IK when adding DTT in pipette solution. These results suggested that SMB might oxidize potassium channels, which relate to adjusting pain sensitivity in pain-sensing DRG neurons.

  2. Inhibition of acid-sensing ion channel currents by propofol in rat dorsal root ganglion neurons.

    PubMed

    Lei, Zhen; Li, Xiaoyu; Wang, Guizhi; Fei, Jianchun; Meng, Tao; Zhang, Xinyu; Yu, Jingya; Yu, Jingui; Li, Jingxin

    2014-04-01

    Acid-sensing ion channels (ASICs), part of the epithelial sodium channel/degenerin family, are activated by extracellular protons. The ASICs play a significant role in the acidosis-mediated perception of pain. The anaesthetic agent propofol also exerts antinociceptive effects, but the underlying mechanisms for this effect are not clear. We used whole-cell patch clamping to investigate the effect of propofol on proton-gated currents in: (i) rat dorsal root ganglion (DRG) neurons; and (ii) HEK293 cells transfected with either ASIC1a or ASIC3. Propofol inhibited the amplitude of proton-gated currents in DRG neurons, but did not change the sensitivity of ASICs to H(+). Notably, propofol altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. In addition, we demonstrated that propofol inhibited ASICs by directly binding with these channels in HEK293 cells. These results suggest that propofol inhibits proton-gated currents in DRG neurons and that inhibition of proton-gated currents explains, in part, the antinociceptive effects of propofol in primary afferent neurons.

  3. AQUAPORIN-1 WATER PERMEABILITY AS A NOVEL DETERMINANT OF AXONAL REGENERATION IN DORSAL ROOT GANGLION NEURONS

    PubMed Central

    Zhang, Hua; Verkman, A.S.

    2015-01-01

    Dorsal root ganglion (DRG) neurons transduce peripheral pain signals through small-diameter, non-myelinated C-fibers, which, when injured, can regenerate to restore pain sensation. Water channel aquaporin-1 (AQP1) is expressed at the plasma membrane of cell bodies and axons of DRG neurons, where it modulates the sensing of certain types of pain. Here, we found that AQP1 is also involved in DRG axonal growth and regeneration by a mechanism that may involve water transport-facilitated extension of axonal outgrowths. Spontaneous and nerve growth factor-stimulated axonal extension was reduced in cultures of AQP1-deficient DRG neurons and DRG explants compared to the wildtype. Axonal growth in AQP1-deficient DRG cultures was rescued by transfection with AQP1 or a different water-transporting AQP (AQP4), but not by a non-water-transporting AQP1 mutant. Following sciatic nerve compression injury AQP1 expression was increased in DRG neurons in wildtype mice, and DRG axonal growth was impaired in AQP1-deficient mice. Our results indicate AQP1 as a novel determinant of DRG axonal regeneration and hence a potential therapeutic target to accelerate neuronal regeneration. PMID:25585012

  4. Aquaporin-1 water permeability as a novel determinant of axonal regeneration in dorsal root ganglion neurons.

    PubMed

    Zhang, Hua; Verkman, A S

    2015-03-01

    Dorsal root ganglion (DRG) neurons transduce peripheral pain signals through small-diameter, non-myelinated C-fibers, which, when injured, can regenerate to restore pain sensation. Water channel aquaporin-1 (AQP1) is expressed at the plasma membrane of cell bodies and axons of DRG neurons, where it modulates the sensing of certain types of pain. Here, we found that AQP1 is also involved in DRG axonal growth and regeneration by a mechanism that may involve water transport-facilitated extension of axonal outgrowths. Spontaneous and nerve growth factor-stimulated axonal extension was reduced in cultures of AQP1-deficient DRG neurons and DRG explants compared to the wildtype. Axonal growth in AQP1-deficient DRG cultures was rescued by transfection with AQP1 or a different water-transporting AQP (AQP4), but not by a non-water-transporting AQP1 mutant. Following sciatic nerve compression injury AQP1 expression was increased in DRG neurons in wildtype mice, and DRG axonal growth was impaired in AQP1-deficient mice. Our results indicate AQP1 as a novel determinant of DRG axonal regeneration and hence a potential therapeutic target to accelerate neuronal regeneration. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Histone acetylation inhibitors promote axon growth in adult dorsal root ganglia neurons.

    PubMed

    Lin, Shen; Nazif, Kutaiba; Smith, Alexander; Baas, Peter W; Smith, George M

    2015-08-01

    Intrinsic mechanisms that guide damaged axons to regenerate following spinal cord injury remain poorly understood. Manipulation of posttranslational modifications of key proteins in mature neurons could reinvigorate growth machinery after injury. One such modification is acetylation, a reversible process controlled by two enzyme families, the histone deacetylases (HDACs) and the histone acetyl transferases (HATs), acting in opposition. Whereas acetylated histones in the nucleus are associated with upregulation of growth-promoting genes, deacetylated tubulin in the axoplasm is associated with more labile microtubules, conducive to axon growth. This study investigates the effects of HAT and HDAC inhibitors on cultured adult dorsal root ganglia (DRG) neurons and shows that inhibition of HATs by anacardic acid or CPTH2 improves axon outgrowth, whereas inhibition of HDACs by TSA or tubacin inhibits axon growth. Anacardic acid increased the number of axons able to cross an inhibitory chondroitin sulfate proteoglycan border. Histone acetylation but not tubulin acetylation level was affected by HAT inhibitors, whereas tubulin acetylation levels were increased in the presence of the HDAC inhibitor tubacin. Although the microtubule-stabilizing drug taxol did not have an effect on the lengths of DRG axons, nocodazole decreased axon lengths. Determining the mechanistic basis will require future studies, but this study shows that inhibitors of HAT can augment axon growth in adult DRG neurons, with the potential of aiding axon growth over inhibitory substrates produced by the glial scar. © 2015 Wiley Periodicals, Inc.

  6. Membrane Mechanics of Primary Afferent Neurons in the Dorsal Root Ganglia of Rats.

    PubMed

    Kanda, Hirosato; Gu, Jianguo G

    2017-04-25

    Membrane mechanics is an important biological factor regulating many cellular functions including cell motility, intercellular and intracellular signaling, gene expression, and membrane ion channel activity. Primary afferent neurons transduce sensory information about temperature, touch, and pain. These sensory functions may be profoundly affected by the states of primary afferent neuron mechanics. However, membrane mechanics of primary afferent neurons is largely unknown. In this study, we established the optical trapping technique for determining membrane mechanics of cultured primary afferent neurons of the dorsal root ganglia (DRG). We further determined the roles of cytoskeleton and membrane lipids in DRG neuron mechanics. We found that DRG neurons had a plasma membrane tension of ∼54 pN/μm, and the tension was significantly decreased to ∼29 pN/μm by cytochalasin D treatment to disrupt actin cytoskeleton and increased to ∼79 pN/μm by methyl-β-cyclodextrin treatment to sequester membrane cholesterol. DRG neuron membrane stiffness was not significantly affected by the cytoskeleton disruption but was significantly increased after cholesterol sequestration. Our findings elucidate membrane mechanical properties of primary afferent neurons, which provide, to our knowledge, a new perspective on their sensory functions. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  7. Na+ Channel Scn1b Gene Regulates Dorsal Root Ganglion Nociceptor Excitability in Vivo*

    PubMed Central

    Lopez-Santiago, Luis F.; Brackenbury, William J.; Chen, Chunling; Isom, Lori L.

    2011-01-01

    Nociceptive dorsal root ganglion (DRG) neurons express tetrodotoxin-sensitive (TTX-S) and -resistant (TTX-R) Na+ current (INa) mediated by voltage-gated Na+ channels (VGSCs). In nociceptive DRG neurons, VGSC β2 subunits, encoded by Scn2b, selectively regulate TTX-S α subunit mRNA and protein expression, ultimately resulting in changes in pain sensitivity. We hypothesized that VGSCs in nociceptive DRG neurons may also be regulated by β1 subunits, encoded by Scn1b. Scn1b null mice are models of Dravet Syndrome, a severe pediatric encephalopathy. Many physiological effects of Scn1b deletion on CNS neurons have been described. In contrast, little is known about the role of Scn1b in peripheral neurons in vivo. Here we demonstrate that Scn1b null DRG neurons exhibit a depolarizing shift in the voltage dependence of TTX-S INa inactivation, reduced persistent TTX-R INa, a prolonged rate of recovery of TTX-R INa from inactivation, and reduced cell surface expression of Nav1.9 compared with their WT littermates. Investigation of action potential firing shows that Scn1b null DRG neurons are hyperexcitable compared with WT. Consistent with this, transient outward K+ current (Ito) is significantly reduced in null DRG neurons. We conclude that Scn1b regulates the electrical excitability of nociceptive DRG neurons in vivo by modulating both INa and IK. PMID:21555511

  8. Porcine dorsal root ganglia ovarian neurons are affected by long lasting testosterone treatment.

    PubMed

    Jana, B; Palus, K; Meller, K; Całka, J

    2016-12-13

    We studied the effect of testosterone overdose on the number, distribution and chemical coding of ovarian neurons in the dorsal root ganglia (DRGs) in pigs. On day 3 of the estrous cycle, the ovaries of both the control and experimental gilts were injected with retrograde tracer Fast Blue. From day 4 of the estrous cycle to the expected day 20 of the second studied cycle, the experimental gilts were injected with testosterone, while the control gilts received oil. After the completion of the protocol the Th16-L5 DRGs were collected. Injections of testosterone increased the testosterone (~3.5 fold) and estradiol-17beta (~1.6 fold) levels in the peripheral blood, and reduced the following in the DRGs: the total number of the Fast Blue-positive perikarya, the population of perikarya in the L2-L4 ganglia, and the numbers of SP(+)/CGRP(+), SP(+)/PACAP(+), SP(+)/nNOS(+) and SP(-)/nNOS(+) perikarya. In the testosterone-injected gilts, the populations of SP(+)CGRP(-), small and large androgen receptors-expressing perikarya were increased. These results suggest that elevated androgen levels during pathological states may regulate the transmission of sensory modalities from the ovary to the spinal cord, and antidromic regulation of the ovarian functions.

  9. Glutathione alleviated peripheral neuropathy in oxaliplatin-treated mice by removing aluminum from dorsal root ganglia

    PubMed Central

    Lee, Minji; Cho, Sungrae; Roh, Kangsan; Chae, Jisook; Park, Jin-Hee; Park, Jaehyun; Lee, Myung-Ah; Kim, Jinheung; Auh, Chung-Kyoon; Yeom, Chang-Hwan; Lee, Sukchan

    2017-01-01

    Oxaliplatin, a platinum-based anti-cancer drug, induces peripheral neuropathy as a side effect and causes cold hyperalgesia in cancer patients receiving anti-cancer chemotherapy. In oxaliplatin-treated mice, aluminum was accumulated in the dorsal root ganglia (DRG), and accumulated aluminum in DRG or other organs aggravated oxaliplatin-induced neuropathic pain. To investigate whether aluminum oxalate, which is the compound of aluminum and oxaliplatin, might be the peripheral neuropathy inducer, the withdrawal responses of mice to coldness, the expression of transient receptor potential ankyrin 1 and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays in DRG were analyzed in mice administered with aluminum oxalate. In addition, the concentrations of aluminum in aluminum oxalate-treated mice were significantly increased compared to those of mice treated with aluminum chloride. To alleviate neuropathic pain, glutathione (GSH), known as an antioxidant and a metal chelator, was injected into oxaliplatin-treated mice. The concentrations of aluminum in the DRG were decreased by the chelation action of GSH. Taken together, behavioral and molecular analyses also supported that aluminum accumulation on the DRG might be a factor for neuropathic pain. This result also suggested that the aluminum chelation by GSH can provide an alleviatory remedy of neuropathic pain for cancer patients with oxaliplatin-induced neuropathic pain. PMID:28386322

  10. Subpopulations of rat dorsal root ganglion neurons express active vesicular acetylcholine transporter.

    PubMed

    Tata, Ada Maria; De Stefano, M Egle; Tomassy, Giulio Srubek; Vilaró, M Teresa; Levey, Allan I; Biagioni, Stefano

    2004-01-15

    The vesicular acetylcholine transporter (VAChT) is a transmembrane protein required, in cholinergic neurons, for selective storage of acetylcholine into synaptic vesicles. Although dorsal root ganglion (DRG) neurons utilize neuropeptides and amino acids for neurotransmission, we have previously demonstrated the presence of a cholinergic system. To investigate whether, in sensory neurons, the vesicular accumulation of acetylcholine relies on the same mechanisms active in classical cholinergic neurons, we investigated VAChT presence, subcellular distribution, and activity. RT-PCR and Western blot analysis demonstrated the presence of VAChT mRNA and protein product in DRG neurons and in the striatum and cortex, used as positive controls. Moreover, in situ hybridization and immunocytochemistry showed VAChT staining located mainly in the medium/large-sized subpopulation of the sensory neurons. A few small neurons were also faintly labeled by immunocytochemistry. In the electron microscope, immunolabeling was associated with vesicle-like elements distributed in the neuronal cytoplasm and in both myelinated and unmyelinated intraganglionic nerve fibers. Finally, [(3)H]acetylcholine active transport, evaluated either in the presence or in the absence of ATP, also demonstrated that, as previously reported, the uptake of acetylcholine by VAChT is ATP dependent. This study suggests that DRG neurons not only are able to synthesize and degrade ACh and to convey cholinergic stimuli but also are capable of accumulating and, possibly, releasing acetylcholine by the same mechanism used by the better known cholinergic neurons.

  11. Carvacrol modulates voltage-gated sodium channels kinetics in dorsal root ganglia.

    PubMed

    Joca, Humberto Cavalcante; Vieira, Daiana Cardoso Oliveira; Vasconcelos, Aliny Perreira; Araújo, Demetrius Antônio Machado; Cruz, Jader Santos

    2015-06-05

    Recent studies have shown that many of plant-derived compounds interact with specific ion channels and thereby modulate many sensing mechanisms, such as nociception. The monoterpenoid carvacrol (5-isopropyl-2-methylphenol) has an anti-nociceptive effect related to a reduction in neuronal excitability and voltage-gated Na(+) channels (NaV) inhibition in peripheral neurons. However, the detailed mechanisms of carvacrol-induced inhibition of neuronal NaV remain elusive. This study explores the interaction between carvacrol and NaV in isolated dorsal root ganglia neurons. Carvacrol reduced the total voltage-gated Na(+) current and tetrodotoxin-resistant (TTX-R) Na(+) current component in a concentration-dependent manner. Carvacrol accelerates current inactivation and induced a negative-shift in voltage-dependence of steady-state fast inactivation in total and TTX-R Na(+) current. Furthermore, carvacrol slowed the recovery from inactivation. Carvacrol provoked a leftward shift in both the voltage-dependence of steady-state inactivation and activation of the TTX-R Na(+) current component. In addition, carvacrol-induced inhibition of TTX-R Na(+) current was enhanced by an increase in stimulation frequency and when neurons were pre-conditioned with long depolarization pulse (5s at -50 mV). Taken all results together, we herein demonstrated that carvacrol affects NaV gating properties. The present findings would help to explain the mechanisms underlying the analgesic activity of carvacrol.

  12. RNA-Seq Analysis of Human Trigeminal and Dorsal Root Ganglia with a Focus on Chemoreceptors

    PubMed Central

    Flegel, Caroline; Schöbel, Nicole; Altmüller, Janine; Becker, Christian; Tannapfel, Andrea; Hatt, Hanns; Gisselmann, Günter

    2015-01-01

    The chemosensory capacity of the somatosensory system relies on the appropriate expression of chemoreceptors, which detect chemical stimuli and transduce sensory information into cellular signals. Knowledge of the complete repertoire of the chemoreceptors expressed in human sensory ganglia is lacking. This study employed the next-generation sequencing technique (RNA-Seq) to conduct the first expression analysis of human trigeminal ganglia (TG) and dorsal root ganglia (DRG). We analyzed the data with a focus on G-protein coupled receptors (GPCRs) and ion channels, which are (potentially) involved in chemosensation by somatosensory neurons in the human TG and DRG. For years, transient receptor potential (TRP) channels have been considered the main group of receptors for chemosensation in the trigeminal system. Interestingly, we could show that sensory ganglia also express a panel of different olfactory receptors (ORs) with putative chemosensory function. To characterize OR expression in more detail, we performed microarray, semi-quantitative RT-PCR experiments, and immunohistochemical staining. Additionally, we analyzed the expression data to identify further known or putative classes of chemoreceptors in the human TG and DRG. Our results give an overview of the major classes of chemoreceptors expressed in the human TG and DRG and provide the basis for a broader understanding of the reception of chemical cues. PMID:26070209

  13. Effects of nano red elemental selenium on sodium currents in rat dorsal root ganglion neurons.

    PubMed

    Yuan, Huijun; Lin, Jiarui; Lan, Tonghan

    2006-01-01

    Nano red elemental selenium (Nano-Se), was demonstrated to be useful in medical and scientific researches. Here, we investigated the effects of Nano-Se on sodium currents on rat dorsal root ganglion neurons (DRG), using the whole-cell patch clamp method. Nano-Se reversibly decrease the I(Na)(TTX-S) in a concentration-dependent, time-dependent and open-channel block manners without affecting I(Na)(TTX-R). It shifted the steady-state activation and inactivation curves for I(Na) to more negative potentials. In the research of recovery from inactivation, the recovery time constant is longer in the present of Nano-Se. Nano-Se had a weaker inhibitory effect on I(Na), compared with marked decrease caused by selenite which indicated that Nano-Se is less neurotoxic than selenite in short-term/large dose treatments and had similar bio availability to sodium selenite. The results of interaction between the effects of Nano-Se and selenite on sodium currents indicated a negative allosteric interaction between the selenite binding site and the Nano-Se binding site or that they have the same competitive binding site.

  14. Taurine-induced modulation of voltage-sensitive Na+ channels in rat dorsal root ganglion neurons.

    PubMed

    Yu, Shan-Shan; Yu, Kuai; Gu, Yan; Ruan, Di-Yun

    2005-08-15

    The physiological role of taurine, an abundant free amino acid in the neural system, is still poorly understood. The aim of this study was to investigate its effect on TTX-sensitive (TTX-S) and TTX-resistant (TTX-R) Na+ currents in enzymatically dissociated neurons from rat dorsal root ganglion (DRG) with conventional whole-cell recording manner under voltage-clamp conditions. A TTX-S Na+ current was recorded preferentially from large DRG neurons and a TTX-R Na+ current preferentially from small ones. For TTX-S Na+ channel, taurine of the concentration > or = 10 mM shifted the activation curve in the depolarizing direction and the inactivation curve in the hyperpolarizing direction. There was no change in the activation curve for TTX-R Na+ channel and the inactivation curve was shifted in the hyperpolarizing direction slightly in the presence of taurine > or = 20 mM. When the recovery kinetics was examined, the presence of taurine resulted in a slower recovery from inactivation of TTX-S currents and no change of TTX-R ones. All the effects of taurine were weakly concentration-dependent and partly recovered quite slowly after washout. Our data indicate that taurine alters the properties of Na+ currents in intact DRG neurons. These may contribute to the understanding of taurine as a natural neuroprotectant and the potential of taurine as a useful medicine for the treatment of sensory neuropathies.

  15. Glutathione alleviated peripheral neuropathy in oxaliplatin-treated mice by removing aluminum from dorsal root ganglia.

    PubMed

    Lee, Minji; Cho, Sungrae; Roh, Kangsan; Chae, Jisook; Park, Jin-Hee; Park, Jaehyun; Lee, Myung-Ah; Kim, Jinheung; Auh, Chung-Kyoon; Yeom, Chang-Hwan; Lee, Sukchan

    2017-01-01

    Oxaliplatin, a platinum-based anti-cancer drug, induces peripheral neuropathy as a side effect and causes cold hyperalgesia in cancer patients receiving anti-cancer chemotherapy. In oxaliplatin-treated mice, aluminum was accumulated in the dorsal root ganglia (DRG), and accumulated aluminum in DRG or other organs aggravated oxaliplatin-induced neuropathic pain. To investigate whether aluminum oxalate, which is the compound of aluminum and oxaliplatin, might be the peripheral neuropathy inducer, the withdrawal responses of mice to coldness, the expression of transient receptor potential ankyrin 1 and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays in DRG were analyzed in mice administered with aluminum oxalate. In addition, the concentrations of aluminum in aluminum oxalate-treated mice were significantly increased compared to those of mice treated with aluminum chloride. To alleviate neuropathic pain, glutathione (GSH), known as an antioxidant and a metal chelator, was injected into oxaliplatin-treated mice. The concentrations of aluminum in the DRG were decreased by the chelation action of GSH. Taken together, behavioral and molecular analyses also supported that aluminum accumulation on the DRG might be a factor for neuropathic pain. This result also suggested that the aluminum chelation by GSH can provide an alleviatory remedy of neuropathic pain for cancer patients with oxaliplatin-induced neuropathic pain.

  16. Temperature dependence of rapidly adapting mechanically activated currents in rat dorsal root ganglion neurons.

    PubMed

    Jia, Zhanfeng; Ling, Jennifer; Gu, Jianguo G

    2012-08-01

    Rapidly adapting mechanically activated channels (RA) are expressed on somatosensory neurons and thought to play a role in mechanical transduction. Because mechanical sensations can be significantly affected by temperatures, we examined thermal sensitivity of RA currents in cultured dorsal root ganglion (DRG) neurons to see if RA channel activity is highly temperature-dependent. RA currents were evoked from DRG neurons by membrane displacements and recorded by the whole-cell patch-clamp recording technique. We found that RA currents were significantly enhanced by warming temperatures from 22 to 32 °C and reduced by cooling temperatures from 24 to 14 °C. RA channel activation exhibited steep temperature-dependence with a large temperature coefficient (Q10>5) and a high activation energy (Ea>30 kcal/mol). We further showed that RA channel activation by mechanical stimulation led to membrane depolarization, which could result in action potential firing at 22 °C or 32 °C but not at 14 °C. Taken together, our results provide the measurements of thermal dynamics and activation energy of RA channels, and suggest that a high energy barrier is present for RA channels to open. These findings are in agreement with temperature sensitivity of mechanical sensations in mammals.

  17. Intracellular TRPA1 mediates Ca2+ release from lysosomes in dorsal root ganglion neurons

    PubMed Central

    Shang, Shujiang; Zhu, Feipeng; Liu, Bin; Chai, Zuying; Wu, Qihui; Hu, Meiqin; Wang, Yuan; Huang, Rong; Zhang, Xiaoyu; Wu, Xi; Sun, Lei; Wang, Yeshi; Wang, Li; Xu, Huadong; Teng, Sasa; Liu, Bing; Zheng, Lianghong; Zhang, Chen; Zhang, Fukang; Feng, Xinghua; Zhu, Desheng

    2016-01-01

    Transient receptor potential A1 (TRPA1) is a nonselective cation channel implicated in thermosensation and inflammatory pain. In this study, we show that TRPA1 (activated by allyl isothiocyanate, acrolein, and 4-hydroxynonenal) elevates the intracellular Ca2+ concentration ([Ca2+]i) in dorsal root ganglion (DRG) neurons in the presence and absence of extracellular Ca2+. Pharmacological and immunocytochemical analyses revealed the presence of TRPA1 channels both on the plasma membrane and in endolysosomes. Confocal line-scan imaging demonstrated Ca2+ signals elicited from individual endolysosomes (“lysosome Ca2+ sparks”) by TRPA1 activation. In physiological solutions, the TRPA1-mediated endolysosomal Ca2+ release contributed to ∼40% of the overall [Ca2+]i rise and directly triggered vesicle exocytosis and calcitonin gene-related peptide release, which greatly enhanced the excitability of DRG neurons. Thus, in addition to working via Ca2+ influx, TRPA1 channels trigger vesicle release in sensory neurons by releasing Ca2+ from lysosome-like organelles. PMID:27799370

  18. Intracellular TRPA1 mediates Ca2+ release from lysosomes in dorsal root ganglion neurons.

    PubMed

    Shang, Shujiang; Zhu, Feipeng; Liu, Bin; Chai, Zuying; Wu, Qihui; Hu, Meiqin; Wang, Yuan; Huang, Rong; Zhang, Xiaoyu; Wu, Xi; Sun, Lei; Wang, Yeshi; Wang, Li; Xu, Huadong; Teng, Sasa; Liu, Bing; Zheng, Lianghong; Zhang, Chen; Zhang, Fukang; Feng, Xinghua; Zhu, Desheng; Wang, Changhe; Liu, Tao; Zhu, Michael X; Zhou, Zhuan

    2016-11-07

    Transient receptor potential A1 (TRPA1) is a nonselective cation channel implicated in thermosensation and inflammatory pain. In this study, we show that TRPA1 (activated by allyl isothiocyanate, acrolein, and 4-hydroxynonenal) elevates the intracellular Ca(2+) concentration ([Ca(2+)]i) in dorsal root ganglion (DRG) neurons in the presence and absence of extracellular Ca(2+) Pharmacological and immunocytochemical analyses revealed the presence of TRPA1 channels both on the plasma membrane and in endolysosomes. Confocal line-scan imaging demonstrated Ca(2+) signals elicited from individual endolysosomes ("lysosome Ca(2+) sparks") by TRPA1 activation. In physiological solutions, the TRPA1-mediated endolysosomal Ca(2+) release contributed to ∼40% of the overall [Ca(2+)]i rise and directly triggered vesicle exocytosis and calcitonin gene-related peptide release, which greatly enhanced the excitability of DRG neurons. Thus, in addition to working via Ca(2+) influx, TRPA1 channels trigger vesicle release in sensory neurons by releasing Ca(2+) from lysosome-like organelles. © 2016 Shang et al.

  19. Electrical injury alters ion channel expression levels and electrophysiological properties in rabbit dorsal root ganglia neurons.

    PubMed

    Chen, Rui; Li, Yue-Jun; Li, Jin-Qing; Lv, Xiao-Xing; Chen, Shao-Zong; Li, Wang-Zhou; Feng, Jian; Li, Xue-Yong

    2011-03-01

    The electrophysiological and morphological changes of nerve fibers induced by electrical injury have been widely addressed. However, the changes of ion channels in neurons after electrical shocks have not been systematically investigated yet. In this study, the sciatic nerves of rabbit were injured by 50 V 50 Hz, 110 V 50 Hz, and 220 V 50 Hz alternating current, respectively. One week later, the expression levels and electrophysiological changes of voltage-gated potassium (Kv) and sodium (Nav) channels in dorsal root ganglia (DRG) neurons were evaluated by RT-PCR, immunofluorescence staining and patch clamp technique. The Nav1.1 expression was decreased by 50V injury. The Kv1.2, Kv1.4, Nav1.1 and Nav1.7 expression levels and Kv current densities were reduced after 110 V injury. Under the 220 V injury circumstance, Kv1.2, Nav1.1, Nav1.7 expression levels, Kv current densities and TTX-R Na(+) current densities were significantly decreased, while TTX-S Na(+) current densities increased. These findings suggest that the expression levels, subunit compositions, and electrophysiological properties of Kv and Nav channels are altered after electrical injury, and the severity of injury gets worse as injury voltage increases. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  20. Teratogenic effects of pyridoxine on the spinal cord and dorsal root ganglia of embryonic chickens.

    PubMed

    Sharp, A A; Fedorovich, Y

    2015-03-19

    Our understanding of the role of somatosensory feedback in regulating motility during chicken embryogenesis and fetal development in general has been hampered by the lack of an approach to selectively alter specific sensory modalities. In adult mammals, pyridoxine overdose has been shown to cause a peripheral sensory neuropathy characterized by a loss of both muscle and cutaneous afferents, but predominated by a loss of proprioception. We have begun to explore the sensitivity of the nervous system in chicken embryos to the application of pyridoxine on embryonic days 7 and 8, after sensory neurons in the lumbosacral region become post-mitotic. Upon examination of the spinal cord, dorsal root ganglion and peripheral nerves, we find that pyridoxine causes a loss of neurotrophic tyrosine kinase receptor type 3-positive neurons, a decrease in the diameter of the muscle innervating nerve tibialis, and a reduction in the number of large diameter axons in this nerve. However, we found no change in the number of Substance P or calcitonin gene-related peptide-positive neurons, the number of motor neurons or the diameter or axonal composition of the femoral cutaneous nerve. Therefore, pyridoxine causes a peripheral sensory neuropathy in embryonic chickens largely consistent with its effects in adult mammals. However, the lesion may be more restricted to proprioception in the chicken embryo. Therefore, pyridoxine lesion induced during embryogenesis in the chicken embryo can be used to assess how the loss of sensation, largely proprioception, alters spontaneous embryonic motility and subsequent motor development.

  1. A model of a rapidly-adapting mechanosensitive current generated by a dorsal root ganglion neuron.

    PubMed

    Fujita, Kazuhisa

    2014-06-01

    I propose a model that replicates the kinetics of a rapidly-adapting mechanosensitive current generated by a dorsal root ganglion (DRG) neuron. When the DRG neuron is mechanically stimulated, an ionic current called a mechanosensitive current flows across its membrane. The kinetics of mechanosensitive currents are broadly classified into three types; rapidly adapting (RA), intermediately adapting, and slowly adapting. The kinetics of RA mechanosensitive currents are particularly intriguing. An RA mechanosensitive current is initially evoked by and rapidly adapts to a mechanical stimulus, but can also respond to an additional stimulus. Furthermore, an antecedent stimulus immediately followed by an additional stimulus suppresses reactivation of the current. The features of the kinetics depend on the characteristics of the mechanotransducer channels. Physiologists have proposed three factors associated with mechanotransducer channels, invoking activation, adaptation, and inactivation. In the present study, these factors are incorporated into an RA mechanosensitive current model. Computer simulations verified that the proposed model replicates the kinetics of real RA DRG mechanosensitive currents. The mechanosensitive current elicited by successive pulse-form stimuli was predominantly desensitized by the inactivating factor. Both the inactivating and adapting factors were involved in desensitization of a double-decker stimulus. The reduction of the sensitivity with decreasing velocity of the stimulus was mainly controlled by the adapting factor.

  2. Characterization of dorsal root ganglion neurons cultured on silicon micro-pillar substrates

    PubMed Central

    Repić, Tihana; Madirazza, Katarina; Bektur, Ezgi; Sapunar, Damir

    2016-01-01

    Our study focuses on characterization of dorsal root ganglion (DRG) neurons cultured on silicon micro-pillar substrates (MPS) with the ultimate goal of designing micro-electrode arrays (MEAs) for successful electrophysiological recordings of DRG neurons. Adult and neonatal DRG neurons were cultured on MPS and glass coverslips for 7 days in vitro. DRG neuronal distribution and morphometric analysis, including neurite alignment and length, was performed on MPS areas with different pillar width and spacing. We showed that MPS provide an environment for growth of adult and neonatal DRG neurons as permissive as control glass surfaces. Neonatal DRG neurons were present on MPS areas with narrow pillar spacing, while adult neurons preferred wider pillar spacing. Compared to the control glass surfaces the neonatal and adult DRG neurons in regions with narrow pillar spacing range developed a smaller number of longer neurites. In the same area, neurites were preferentially oriented along three directional axes at 30°, 90° and 150°. MPS architecture influenced growth directionality of all main DRG neuronal subtypes. We can conclude that specific micro-pillar substrate topography affects the morphology of DRG neurons. This knowledge can enable development of MEAs with precisely defined physical features for various neuroscience applications. PMID:28008963

  3. Targeting dorsal root ganglia and primary sensory neurons for the treatment of chronic pain.

    PubMed

    Berta, Temugin; Qadri, Yawar; Tan, Ping-Heng; Ji, Ru-Rong

    2017-07-01

    Currently the treatment of chronic pain is inadequate and compromised by debilitating central nervous system side effects. Here we discuss new therapeutic strategies that target dorsal root ganglia (DRGs) in the peripheral nervous system for a better and safer treatment of chronic pain. Areas covered: The DRGs contain the cell bodies of primary sensory neurons including nociceptive neurons. After painful injuries, primary sensory neurons demonstrate maladaptive molecular changes in DRG cell bodies and in their axons. These changes result in hypersensitivity and hyperexcitability of sensory neurons (peripheral sensitization) and are crucial for the onset and maintenance of chronic pain. We discuss the following new strategies to target DRGs and primary sensory neurons as a means of alleviating chronic pain and minimizing side effects: inhibition of sensory neuron-expressing ion channels such as TRPA1, TRPV1, and Nav1.7, selective blockade of C- and Aβ-afferent fibers, gene therapy, and implantation of bone marrow stem cells. Expert opinion: These peripheral pharmacological treatments, as well as gene and cell therapies, aimed at DRG tissues and primary sensory neurons can offer better and safer treatments for inflammatory, neuropathic, cancer, and other chronic pain states.

  4. Multiunit Activity-Based Real-Time Limb-State Estimation from Dorsal Root Ganglion Recordings

    PubMed Central

    Han, Sungmin; Chu, Jun-Uk; Kim, Hyungmin; Park, Jong Woong; Youn, Inchan

    2017-01-01

    Proprioceptive afferent activities could be useful for providing sensory feedback signals for closed-loop control during functional electrical stimulation (FES). However, most previous studies have used the single-unit activity of individual neurons to extract sensory information from proprioceptive afferents. This study proposes a new decoding method to estimate ankle and knee joint angles using multiunit activity data. Proprioceptive afferent signals were recorded from a dorsal root ganglion with a single-shank microelectrode during passive movements of the ankle and knee joints, and joint angles were measured as kinematic data. The mean absolute value (MAV) was extracted from the multiunit activity data, and a dynamically driven recurrent neural network (DDRNN) was used to estimate ankle and knee joint angles. The multiunit activity-based MAV feature was sufficiently informative to estimate limb states, and the DDRNN showed a better decoding performance than conventional linear estimators. In addition, processing time delay satisfied real-time constraints. These results demonstrated that the proposed method could be applicable for providing real-time sensory feedback signals in closed-loop FES systems. PMID:28276474

  5. N-(4-pyridyl) methyl carbamate inhibits fast potassium currents in guinea pig dorsal root ganglion cells.

    PubMed

    Sun, Wenjing; Smith, Daniel; Bryn, Steven; Borgens, Richard; Shi, Riyi

    2009-02-15

    Axonal demyelination is a critical pathological phenomenon associated with spinal cord injury and multiple sclerosis (MS). Previous studies demonstrated that 4-Aminopyridine, a fast potassium channel blocker, enhances impulse conduction on damaged and/or demyelinated axons, allowing for functional recovery in spinal cord injuries and MS, but with severe therapeutic limitations. To continue to explore the therapeutic value of blocking fast potassium channels while circumventing the side effects of 4-AP, we have developed three novel 4-AP derivatives that enhance impulse conduction in spinal cord trauma. In the current study, we have shown that one of these three derivatives, N-(4-pyridyl) methyl carbamates (MC), significantly inhibits a fast, I(A) like potassium current in guinea pig dorsal root ganglion cells in a whole cell patch clamp configuration. This inhibition of I(A) likely plays a critical role in MC's ability to restore conduction in mechanically injured spinal cord axons and may present a viable alternative to 4-AP for individuals with spinal cord injury or MS. From this, compounds with greater efficacy and perhaps less side effects will likely emerge in the near future, which will greatly enhance the functional restoration and lessen the suffering of SCI and MS patients.

  6. Differential effects of HIV infected macrophages on dorsal root ganglia neurons and axons

    PubMed Central

    Hahn, Katrin; Robinson, Barry; Anderson, Caroline; Li, Wenxue; Pardo, Carlos A.; Morgello, Susan; Simpson, David; Nath, Avindra

    2008-01-01

    Human immunodeficiency virus-associated distal-symmetric neuropathy (HIV-DSP) is the most common neurological complication of HIV infection. The pathophysiology of HIV-DSP is poorly understood and no treatment is available for this entity. The dorsal root ganglia (DRG) are the principal sites of neuronal damage and are associated with reactive mononuclear phagocytes as well as HIV-infected macrophages. To determine the role of HIV-infected macrophages in the pathogenesis of HIV-DSP, we developed a technique for culturing human DRG’s. When the dissociated DRG neurons were exposed to supernatants from macrophages infected with CXCR4 or CCR5 tropic HIV-1 strains axonal retraction was observed without neuronal cell death but there was mitochondrial dysfunction in the neuronal cell body. Even though CXCR4 and CCR5 were expressed on the DRG neurons, the effects were independent of these receptors. Antioxidants rescued the neuronal cell body but not the axon from the toxic effects of the culture supernatants. Further, peripheral nerves of HIV-infected patients obtained at autopsy did not show evidence of increased oxidative stress. These observations suggest a differential effect on the axon and cell body. Different mechanisms of injury may be operative in these two structures. PMID:18177640

  7. Comprehensive Method for Culturing Embryonic Dorsal Root Ganglion Neurons for Seahorse Extracellular Flux XF24 Analysis

    PubMed Central

    Lange, Miranda; Zeng, Yan; Knight, Andrew; Windebank, Anthony; Trushina, Eugenia

    2012-01-01

    Changes in mitochondrial dynamics and function contribute to progression of multiple neurodegenerative diseases including peripheral neuropathies. The Seahorse Extracellular Flux XF24 analyzer provides a comprehensive assessment of the relative state of glycolytic and aerobic metabolism in live cells making this method instrumental in assessing mitochondrial function. One of the most important steps in the analysis of mitochondrial respiration using the Seahorse XF24 analyzer is plating a uniform monolayer of firmly attached cells. However, culturing of primary dorsal root ganglion (DRG) neurons is associated with multiple challenges, including their propensity to form clumps and detach from the culture plate. This could significantly interfere with proper analysis and interpretation of data. We have tested multiple cell culture parameters including coating substrates, culture medium, XF24 microplate plastics, and plating techniques in order to optimize plating conditions. Here we describe a highly reproducible method to obtain neuron-enriched monolayers of securely attached dissociated primary embryonic (E15) rat DRG neurons suitable for analysis with the Seahorse XF24 platform. PMID:23248613

  8. Comprehensive Method for Culturing Embryonic Dorsal Root Ganglion Neurons for Seahorse Extracellular Flux XF24 Analysis.

    PubMed

    Lange, Miranda; Zeng, Yan; Knight, Andrew; Windebank, Anthony; Trushina, Eugenia

    2012-01-01

    Changes in mitochondrial dynamics and function contribute to progression of multiple neurodegenerative diseases including peripheral neuropathies. The Seahorse Extracellular Flux XF24 analyzer provides a comprehensive assessment of the relative state of glycolytic and aerobic metabolism in live cells making this method instrumental in assessing mitochondrial function. One of the most important steps in the analysis of mitochondrial respiration using the Seahorse XF24 analyzer is plating a uniform monolayer of firmly attached cells. However, culturing of primary dorsal root ganglion (DRG) neurons is associated with multiple challenges, including their propensity to form clumps and detach from the culture plate. This could significantly interfere with proper analysis and interpretation of data. We have tested multiple cell culture parameters including coating substrates, culture medium, XF24 microplate plastics, and plating techniques in order to optimize plating conditions. Here we describe a highly reproducible method to obtain neuron-enriched monolayers of securely attached dissociated primary embryonic (E15) rat DRG neurons suitable for analysis with the Seahorse XF24 platform.

  9. MrgX2 is a high potency cortistatin receptor expressed in dorsal root ganglion.

    PubMed

    Robas, Nicola; Mead, Emma; Fidock, Mark

    2003-11-07

    MrgX2 is a recently identified orphan G-protein-coupled receptor whose ligand and physiological function were unknown. Here we describe cortistatin, a neuropeptide for which no specific receptor has been identified previously, as a high potency ligand at MrgX2. Cortistatin has several biological functions including roles in sleep regulation, locomotor activity, and cortical function. Using a "reverse pharmacology" approach, we have identified a number of additional cyclic peptide agonists for MrgX2, determined their rank order of potency, and demonstrated that this receptor has a pharmacological profile distinct from the other characterized members of the Mrg (Mas-related genes) family. In MrgX2-expressing cells, cortistatin-stimulated increases in intracellular Ca2+ but had no effect on basal or forskolin-stimulated cAMP levels, suggesting that this receptor is Gq-coupled. Immunohistochemical and quantitative PCR studies show MrgX2 to have a limited expression profile, both peripheral and within the central nervous system, with highest levels in dorsal root ganglion.

  10. Evaluation of Cisplatin Neurotoxicity in Cultured Rat Dorsal Root Ganglia via Cytosolic Calcium Accumulation

    PubMed Central

    Erol, Kevser; Yiğitaslan, Semra; Ünel, Çiğdem; Kaygısız, Bilgin; Yıldırım, Engin

    2016-01-01

    Background: Calcium homeostasis is considered to be important in antineoplastic as well as in neurotoxic adverse effects of cisplatin. Aims: This study aimed to investigate the role of Ca2+ in cisplatin neurotoxicity in cultured rat dorsal root ganglia (DRG) cells. Study Design: Cell culture study. Methods: DRG cells prepared from 1-day old Sprague-Dawley rats were used to determine the role of Ca2+ in the cisplatin (10–600 μM) neurotoxicity. The cells were incubated with cisplatin plus nimodipine (1–3 μM), dizocilpine (MK-801) (1–3 μM) or thapsigargin (100–300 nM). Toxicity of cisplatinon DRG cells was determined by the MTT assay. Results: The neurotoxicity of cisplatin was significant when used in high concentrations (100–600 μM). Nimodipine (1 μM) but not MK-801 or thapsigargin prevented the neurotoxic effects of 200 μM of cisplatin. Conclusion: Voltage-dependent calcium channels may play a role in cisplatin neurotoxicity. PMID:27403382

  11. Rearrangement of microtubule associated protein parallels the morphological transformation of neurons from dorsal root ganglion.

    PubMed

    Hernández, M A; Avila, J; Moya, F; Alberto, C

    1989-01-01

    In primary cultures of dorsal root ganglion cells from rat embryos, neurons undergo a morphological transformation from a bipolar to a differentiated pseudo-unipolar shape, resembling their developmental stages in vivo. Cells present in these cultures are characterized here by immunological criteria using monoclonal and polyclonal antibodies against microtubule associated proteins MAP1 and MAP2 and against tubulin. After development for seven days in culture, antibodies against microtubule associated proteins MAP1 brightly labeled cells with neuronal morphology and lightly stained cells with the shape of Schwann cells. In addition, an extended network of neuronal processes was labeled with this antibody. Anti-microtubule associated protein MAP2 stained only neurons and a more restricted network of neuronal processes. The compartmentalization of microtubule associated protein MAP2 during the maturation process was followed by double-labeling with antibodies to microtubule associated proteins MAP1 and MAP2. Initially, microtubule associated protein MAP2 was present in the cell body and the two processes of bipolar neurons. Subsequently, the labeling of both processes changed, depending on neuronal morphology. In neurons in which both processes were approaching one another, one of these neurites was stained predominantly with anti-microtubule associated protein MAP2. Finally, in pseudo, unipolar neurons, anti-microtubule associated protein MAP2 labeling was found in the cell body and excluded from the more distal processes.

  12. Long term effects of lipopolysaccharide on satellite glial cells in mouse dorsal root ganglia.

    PubMed

    Blum, E; Procacci, P; Conte, V; Sartori, P; Hanani, M

    2017-01-01

    Lipopolysaccharide (LPS) has been used extensively to study neuroinflammation, but usually its effects were examined acutely (24h<). We have shown previously that a single intraperitoneal LPS injection activated satellite glial cells (SGCs) in mouse dorsal root ganglia (DRG) and altered several functional parameters in these cells for at least one week. Here we asked whether the LPS effects would persist for 1 month. We injected mice with a single LPS dose and tested pain behavior, assessed SGCs activation in DRG using glial fibrillary acidic protein (GFAP) immunostaining, and injected a fluorescent dye intracellularly to study intercellular coupling. Electron microscopy was used to quantitate changes in gap junctions. We found that at 30 days post-LPS the threshold to mechanical stimulation was lower than in controls. GFAP expression, as well as the magnitude of dye coupling among SGCs were greater than in controls. Electron microscopy analysis supported these results, showing a greater number of gap junctions and an abnormal growth of SGC processes. These changes were significant, but less prominent than at 7 days post-LPS. We conclude that a single LPS injection exerts long-term behavioral and cellular changes. The results are consistent with the idea that SGC activation contributes to hyperalgesia.

  13. Dorsal Root Ganglia Sensory Neuronal Cultures: a tool for drug discovery for peripheral neuropathies

    PubMed Central

    Melli, Giorgia; Höke, Ahmet

    2010-01-01

    Background Peripheral neuropathies affect many people worldwide and are caused by or associated with a wide range of conditions, both genetic and acquired. Current therapies are directed at symptomatic control because no effective regenerative treatment exists. Primary challenge is that mechanisms that lead to distal axonal degeneration, a common feature of all peripheral neuropathies, are largely unknown. Objective/Methods To address the role and specific characteristics of dorsal root ganglia (DRG) derived sensory neuron culture system as a useful model in evaluating the pathogenic mechanisms of peripheral neuropathies and examination and validation of potential therapeutic compounds. A thorough review of the recent literature was completed and select examples of the use of DRG neurons in different peripheral neuropathy models were chosen to highlight the utility of these cultures. Conclusion Many useful models of different peripheral neuropathies have been developed using DRG neuronal culture and potential therapeutic targets have been examined, but so far none of the potential therapeutic compounds have succeeded in clinical trials. In recent years, focus has changed to evaluation of axon degeneration as the primary outcome measure advocating a drug development strategy starting with phenotypic drug screening, followed by validation in primary complex co-cultures and animal models. PMID:20657751

  14. Substrate Availability of Mutant SPT Alters Neuronal Branching and Growth Cone Dynamics in Dorsal Root Ganglia

    PubMed Central

    Jun, Byung Kyu; Chandra, Ankush; Kuljis, Dika; Schmidt, Brian P.

    2015-01-01

    Serine palmitoyltransferase (SPT) is a key enzyme in the first step of sphingolipid biosynthesis. Mutations in the SPTLC1 gene that encodes for SPT subunits cause hereditary sensory neuropathy type 1. However, little is understood about how mutant SPT regulates mechanisms of sensory neuron and axonal growth. Using transgenic mice overexpressing the C133W SPT mutant, we found that mutant dorsal root ganglia (DRG) during growth in vitro exhibit increased neurite length and branching, coinciding with elevated expression of actin-cross-linking proteins at the neuronal growth cone, namely phosphorylated Ezrin/Radixin/Moesin. In addition, inhibition of SPT was able to reverse the mutant phenotype. Because mutant SPT preferentially uses l-alanine over its canonical substrate l-serine, we also investigated the effects of substrate availability on DRG neurons. Supplementation with l-serine or removal of l-alanine independently restored normal growth patterns in mutant SPTLC1C133W DRG. Therefore, we report that substrate availability and selectivity of SPT influence the regulation of neurite growth in DRG neurons. SIGNIFICANCE STATEMENT Hereditary sensory neuropathy type 1 is an autosomal-dominant disorder that leads to a sensory neuropathy due to mutations in the serine palmitoyltransferase (SPT) enzyme. We investigated how mutant SPT and substrate levels regulate neurite growth. Because SPT is an important enzyme in the synthesis of sphingolipids, our data are of broader significance to other peripheral and metabolic disorders. PMID:26446223

  15. Multiunit Activity-Based Real-Time Limb-State Estimation from Dorsal Root Ganglion Recordings.

    PubMed

    Han, Sungmin; Chu, Jun-Uk; Kim, Hyungmin; Park, Jong Woong; Youn, Inchan

    2017-03-09

    Proprioceptive afferent activities could be useful for providing sensory feedback signals for closed-loop control during functional electrical stimulation (FES). However, most previous studies have used the single-unit activity of individual neurons to extract sensory information from proprioceptive afferents. This study proposes a new decoding method to estimate ankle and knee joint angles using multiunit activity data. Proprioceptive afferent signals were recorded from a dorsal root ganglion with a single-shank microelectrode during passive movements of the ankle and knee joints, and joint angles were measured as kinematic data. The mean absolute value (MAV) was extracted from the multiunit activity data, and a dynamically driven recurrent neural network (DDRNN) was used to estimate ankle and knee joint angles. The multiunit activity-based MAV feature was sufficiently informative to estimate limb states, and the DDRNN showed a better decoding performance than conventional linear estimators. In addition, processing time delay satisfied real-time constraints. These results demonstrated that the proposed method could be applicable for providing real-time sensory feedback signals in closed-loop FES systems.

  16. Support and satellite cells within the rabbit dorsal root ganglion: ultrastructure of a perineuronal support cell.

    PubMed

    Siemionow, Kris; Weinstein, James N; McLain, Robert F

    2006-08-01

    The membrane, nucleus, and cytoplasmic contents of satellite cells were evaluated using a transmission electron microscope. To delineate satellite cell morphometries. The role of the satellite support cells associated with the neuronal cell bodies remains poorly understood. Previous research has identified one type of satellite support cells. Dorsal root ganglions were excised from 10 adult New Zealand White rabbits. Sections from L2-L5 ganglions were prepared, cut, and analyzed under a transmission electron microscope. A total of 190 neurons and their associated satellite cells were selected for analysis. Three subgroups of satellite cells were identified. The two predominant subgroups consisted of previously described satellite cells. The third subgroup consisted of highly complex and unusual cells. Nineteen satellite cells (4%) did not conform to any previous description of glial cells. Cells were characterized by larger nuclei, with numerous inclusions, and by extensively convoluted reflections of the cellular membrane. These cells were "perched" or "piggy-backed" on top of a convoluted and multilayered cytoplasmic sheet. A new type of support cell representing a different cell line or a highly adapted cell with specific functional capacities was identified.

  17. Peripheral target reinnervation following orthotopic grafting of fetal allogeneic and xenogeneic dorsal root ganglia.

    PubMed

    Rosario, C M; Dubovy, P; Sidman, R L; Aldskogius, H

    1995-04-01

    The sensory reinnervation of dermal papillae and epidermis of glabrous skin, interosseal Pacinian corpuscles, and muscle spindles of the soleus and extensor digitorum longus muscles has been examined 1, 3, and 8 months (allografts) or 3 and 5 weeks (xenografts) following orthotopic grafting of fetal allogeneic or xenogeneic (mouse) dorsal root ganglia (DRG) into ganglionectomized adult rats. Sensory axons in target tissues were identified immunohistochemically by monoclonal antibodies against growth-associated peptide (GAP-43), heavy neurofilament protein (RT-97), anti-mouse-specific membrane glycoprotein Thy-1.2, and polyclonal antibody to calcitonin gene-related peptide (CGRP). Absence of axonal marker staining in target structures of control animals 10 days or 3 months following ipsilateral enucleation of the L3-L6 DRG without grafting indicated an elimination of host normal (intact), regenerating, or collaterally sprouting nerve fibers. The consistent finding of immunolabeled axons ending free and in encapsulated structures in the target tissues of both allo- and xenografted rats indicates that grafted primary sensory neurons can survive and send axonal processes down the full length of the hind limb, to terminate in host target tissues. Axons of xenografted fetal mouse sensory neurons grow in adult rat hosts for distances of 4 cm or more, attaining lengths far greater than called for by their normal developmental programs.

  18. Neuronal somatic ATP release triggers neuron-satellite glial cell communication in dorsal root ganglia.

    PubMed

    Zhang, X; Chen, Y; Wang, C; Huang, L-Y M

    2007-06-05

    It has been generally assumed that the cell body (soma) of a neuron, which contains the nucleus, is mainly responsible for synthesis of macromolecules and has a limited role in cell-to-cell communication. Using sniffer patch recordings, we show here that electrical stimulation of dorsal root ganglion (DRG) neurons elicits robust vesicular ATP release from their somata. The rate of release events increases with the frequency of nerve stimulation; external Ca(2+) entry is required for the release. FM1-43 photoconversion analysis further reveals that small clear vesicles participate in exocytosis. In addition, the released ATP activates P2X7 receptors in satellite cells that enwrap each DRG neuron and triggers the communication between neuronal somata and glial cells. Blocking L-type Ca(2+) channels completely eliminates the neuron-glia communication. We further show that activation of P2X7 receptors can lead to the release of tumor necrosis factor-alpha (TNFalpha) from satellite cells. TNFalpha in turn potentiates the P2X3 receptor-mediated responses and increases the excitability of DRG neurons. This study provides strong evidence that somata of DRG neurons actively release transmitters and play a crucial role in bidirectional communication between neurons and surrounding satellite glial cells. These results also suggest that, contrary to the conventional view, neuronal somata have a significant role in cell-cell signaling.

  19. Mechanical sensitivity and electrophysiological properties of acutely dissociated dorsal root ganglion neurons of rats.

    PubMed

    Viatchenko-Karpinski, Viacheslav; Gu, Jianguo G

    2016-11-10

    Primary afferent fibers use mechanically activated (MA) currents to transduce innocuous and noxious mechanical stimuli. However, it is largely unknown about the differences in MA currents between the afferents for sensing innocuous and noxious stimuli. In the present study, we used dorsal root ganglion (DRG) neurons acutely dissociated from rats and studied their MA currents and also their intrinsic membrane properties. Recorded from small-sized DRG neurons, we found that most of these neurons were mechanically sensitive (MS) showing MA currents. The MS neurons could be classified into nociceptive-like mechanically sensitive (Noci-MS) and non-nociceptive-like mechanically sensitive (nonNoci-MS) neurons based on their action potential shapes. Noci-MS neurons responded to mechanical stimulation with three types of MA currents, rapidly adapting (RA), intermediately adapting (IA), and slowly adapting (SA) currents. In contrast, almost all nonNoci-MS neurons showed RA current type in response to mechanical stimulation. Mechanical thresholds had a broad range for both nonNoci-MS and Noci-MS neurons, and the thresholds were not significantly different between them. However, MA current densities were significantly smaller in Noci-MS than in nonNoci-MS neurons. Noci-MS and nonNoci-MS neurons also showed significant differences in their electrophysiological properties including action potential (AP) thresholds and AP firing patterns. These differences may contribute to the differential sensory encoding for innocuous and noxious mechanical stimuli. Copyright © 2016. Published by Elsevier Ireland Ltd.

  20. Mercury in the dorsal root ganglia of rats treated with inorganic or organic mercury

    SciTech Connect

    Schioenning, J.D.; Moeller-Madsen, B.; Danscher, G. )

    1991-10-01

    Autometallographic silver amplification has been used to demonstrate the localization of mercury deposits in rat dorsal root ganglia after repeated intraperitoneal injections of mercuric chloride or methylmercuric chloride. The silver-enhanced mercury deposits were demonstrated with the light and electron microscope. The degree of intracellular staining of the individual cells depended on the mercury compound and total dosage. Ganglion cells (types A and B) and macrophages were found to accumulate mercury after a total dosage of 400 {mu}g HgCl{sub 2}. After 600 {mu}g HgCl{sub 2}, satellite cells, endothelial cells and fibroblasts were additionally found to contain mercury deposits. Treatment with 6,000 {mu}g CH{sub 3}HgCl caused faint staining of type A and B ganglion cells and fibroblasts. Macrophages, however, were the most heavily stained cells after treatment with CH{sub 3}HgCl. Ultrastructurally, mercury was exclusively located in lysosomes. This was irrespective of the cell type and mercury compound used for treatment.

  1. Effect of paclitaxel on transient receptor potential vanilloid 1 in rat dorsal root ganglion.

    PubMed

    Hara, Tomomi; Chiba, Terumasa; Abe, Kenji; Makabe, Akiko; Ikeno, Souichi; Kawakami, Kazuyoshi; Utsunomiya, Iku; Hama, Toshihiro; Taguchi, Kyoji

    2013-06-01

    Peripheral neuropathy is a common adverse effect of paclitaxel treatment. To analyze the contribution of transient receptor potential vanilloid 1 (TRPV1) in the development of paclitaxel-induced thermal hyperalgesia, TRPV1 expression in the rat dorsal root ganglion (DRG) was analyzed after paclitaxel treatment. Behavioral assessment using the tail-flick test showed that intraperitoneal administration of 2 and 4 mg/kg paclitaxel induced thermal hyperalgesia after days 7, 14, and 21. Paclitaxel-induced thermal hyperalgesia after day 14 was significantly inhibited by the TRP antagonist ruthenium red (3 mg/kg, s.c.) and the TRPV1 antagonist capsazepine (30 mg/kg, s.c.). Paclitaxel (2 and 4 mg/kg) treatment increased the expression of TRPV1 mRNA and protein in DRG neurons. Immunohistochemistry showed that paclitaxel (4 mg/kg) treatment increased TRPV1 protein expression in small and medium DRG neurons 14 days after treatment. Antibody double labeling revealed that isolectin B4-positive small DRG neurons co-expressed TRPV1. TRPV1 immunostaining was up-regulated in paw skin day 14 after paclitaxel treatment. Moreover, in situ hybridization histochemistry revealed that most of the TRPV1 mRNA-labeled neurons in the DRG were small or medium in size. These results suggest that paclitaxel treatment increases TRPV1 expression in DRG neurons and may contribute to functional peripheral neuropathic pain.

  2. Chronic NGF treatment induces somatic hyperexcitability in cultured dorsal root ganglion neurons of the rat.

    PubMed

    Kayano, Tomohiko; Kitamura, Naoki; Moriya, Taiki; Kuwahara, Takeshi; Komagiri, You; Toescu, Emil C; Shibuya, Izumi

    2013-01-01

    Adult rat dorsal root ganglion (DRG) neurons cultured in the presence of 100-ng/mL NGF were reported to show spontaneous action potentials in the cell-attached recording. In this study, underlying mechanisms were examined in the whole-cell and outside-out voltage clamp recording. In 75% neurons with on-cell firing, transient inward current spikes were repetitively recorded in the voltage clamp mode at -50 mV in the whole-cell configuration (named "Isp"). Isp with stable amplitudes occurred in an all-or-none fashion, and was abolished by TTX (< 100 nM), lidocaine (< 1 mM) and a reduction of extracellular Na(+) (154 to 100 mM) in an all-or-none fashion, suggesting that Isp reflects spontaneous dicharges occurring at the loosely voltage-clamped regions. Isp was also observed in the excised outside-out patches and the kinetics and the sensitivity to TTX and lidocaine resembled those in the whole-cell. Spontaneous action potentials were also recorded in the current clamp mode. Small subthreshold spikes often preceded the action potentials. When the localized discharge affected a whole-somatic membrane potential to overcome a threshold, the action potential generated. These results indicate that the triggering sources of the action potential exist in the somatic membrane itself in NGF-treated DRG neurons.

  3. Decreased voltage-gated potassium currents in rat dorsal root ganglion neurons after chronic constriction injury.

    PubMed

    Xiao, Yun; Wu, Yang; Zhao, Bo; Xia, Zhongyuan

    2016-01-20

    Voltage-gated potassium channels (KV) regulate pain transmission by controlling neuronal excitability. Changes in KV expression patterns may thus contribute toward hyperalgesia following nerve injury. The aim of this study was to characterize KV current density in dorsal root ganglion (DRG) neurons following chronic constriction injury (CCI) of the right sciatic nerve, a robust model of post-traumatic neuropathic pain. The study examined changes in small-diameter potassium ion currents (<30 µm) in neurons in the L4-L6 DRG following CCI by whole-cell patch-clamping and the association with post-CCI mechanical and thermal nociceptive thresholds. Compared with the control group, 7 days after CCI, the mechanical force and temperature required to elicit ipsilateral foot withdrawal decreased significantly, indicating tactile allodynia and thermal hyperalgesia. Post-CCI neurons had a significantly lower rheobase current and depolarized resting membrane potential than controls, suggesting KV current downregulation. Some ipsilateral DRG neurons also had spontaneous action potentials and repetitive firing. There was a 55% reduction in the total KV current density caused by a 55% decrease in the sustained delayed rectifier potassium ion current (IK) density and a 17% decrease in the transient A-type potassium ion current (IA) density. These results indicated that changes in DRG neuron IK and IA current density and concomitant afferent hyperexcitability may contribute toward neuropathic pain following injury. The rat CCI model may prove valuable for examining pathogenic mechanisms and potential therapies, such as KV channel modulators.

  4. Coexpression of Runx1 and Runx3 in mechanoreceptive dorsal root ganglion neurons.

    PubMed

    Yoshikawa, Masaaki; Murakami, Yuuki; Senzaki, Kouji; Masuda, Tomoyuki; Ozaki, Shigeru; Ito, Yoshiaki; Shiga, Takashi

    2013-06-01

    Runt-related transcription factors (Runx) regulate the development of various cells. It has been reported that Runx1 and Runx3 are expressed in distinct subpopulations of primary sensory neurons in the dorsal root ganglion (DRG), and play important roles in the differentiation of nociceptive and proprioceptive neurons, respectively. In the present study, we examined the developmental changes of the expression of Runx1 and Runx3 in the mouse DRG during embryonic and postnatal stages. We found that the expression of Runx3 preceded that of Runx1, but dramatically decreased before birth, whereas the Runx1 expression was maintained during postnatal periods. These results suggest that roles of Runx1 and Runx3 may change dynamically in the differentiation and maturation of DRG neurons. In addition, several DRG neurons expressed both Runx1 and Runx3 throughout embryonic and postnatal stages and many Runx3-expressing DRG neurons coexpressed Runx1 at postnatal day 28. Double and triple labeling studies suggest that some of the Runx1/Runx3-double expressing neurons coexpressed TrkB, c-ret, and TrkC, which have been shown in the mechanoreceptive DRG neurons. These results suggest that Runx1/Runx3-double expressing neurons may represent mechanoreceptive properties in the DRG.

  5. Riboflavin Arrests Cisplatin-Induced Neurotoxicity by Ameliorating Cellular Damage in Dorsal Root Ganglion Cells.

    PubMed

    Salman, Maria; Naseem, Imrana; Hassan, Iftekhar; Khan, Aijaz A; Alhazza, Ibrahim M

    2015-01-01

    Cis-Diamminedichloroplatinum II- (CP-) induced neurotoxicity is one of the least explored aspects of this drug. Dorsal root ganglia (DRG) cells are considered as the primary target, and their damage plays a vital role in pathogenesis and etiology of CP-induced neurotoxicity. The present study is aimed at confirming if riboflavin (RF) has any protective role in shielding the DRG from CP-induced toxicity. After conducting the established treatment strategy on mice under photoillumination, it was observed that, despite the fact that RF alone is partially toxic, its combination with CP significantly ameliorated the drug-induced damage in DRG cells as evidenced by histological analysis. In addition, it was interesting to observe that the combination group (RF + CP) was able to induce apoptosis in the target cells up to a significant extent which is considered as the most preferred way of countering cancer cells. Therefore, RF can act as an effective adjuvant compound in CP-based chemoradiotherapy to improve clinical outcomes in the contemporary anticancer treatment regimes.

  6. Long term follow-up results of dorsal root entry zone lesions for intractable pain after brachial plexus avulsion injuries.

    PubMed

    Chen, H J; Tu, Y K

    2006-01-01

    Brachial plexus avulsion injury is one of the major complications after traffic, especially motorcycle accidents and machine injuries. Intractable pain and paralysis of the affected limbs are the major neurological deficits. During the past 18 years, we have encountered and treated more than 500 cases with brachial plexus avulsion injuries. Dorsal root entry zone lesions (DREZ) made by thermocoagulation were performed for intractable pain in 60 cases. Forty cases were under regular follow-up for 5-18 years. In early postoperative stage, the pain relief rate was excellent or good in 32 cases (80%). The pain relief rate dropped to 60% in 5 year follow-up period and only 9 cases (50%) had excellent or good result in 10 year follow-up. Reconstructive procedures were performed in almost all patients in the last 10 years. Dorsal root entry zone lesion is an effective procedure for pain control after brachial plexus avulsion injuries.

  7. [Experimental research on substance P content of hypothalamus and dorsal root ganglia in rats with lumbar vertebrae Gucuofeng model].

    PubMed

    Chen, Bo; Lin, Xun; Pang, Jian; Kong, Ling-jun; Zhan, Hong-sheng; Cheng, Ying-wu; Shi, Yin-yu

    2015-01-01

    To detect the effects of lumbar vertebrae Gucuofeng on the substance P content of hypothalamus and dorsal root ganglia in rat models. A hundred and twenty SPF level SD male rats with the weight of 350 to 450 g were randomly divided into rotary fixation group (RF group), simple fixation group (SF group) and sham-operation group (Sham group). The external link fixation system was implanted into the L4-L6 of rats in RF group and SF group; and in RF group, that the L5 spinous process was rotated to the right resulted in L4, L5, L6 spinous process not collinear; in SF group, the external link fixation system was simply implanted and not rotated. The rats of Sham group were not implanted the external link fixation system and only open and suture. The substance P content of hypothalamus and dorsal root ganglia were detected at 1, 4, 8, 12 weeks after operation. Substance P content of hypothalamus in RF group and SF group was lower than Sham group at 1, 4, 8 weeks after operation (P<0.05). Substance P content of dorsal root ganglia was higher than Sham group at 1, 4, 8, 12 weeks after operation (P<0.05). There was no significant differences in the substance P content of hypothalamus among three groups at 12 weeks after operation (P>0.05). Lumbar vertebrae Gucuofeng can inhibit the analgesic activity of substance P in hypothalamus and promote the synthesis and transmission of substance P in dorsal root ganglia, so as to cause or aggravate the pain.

  8. [Neurite-stimulating effect of Hirudo medicinalis salivary gland secreting factors in organotypic culture of the dorsal root ganglia].

    PubMed

    Chalisova, N I; Baskova, I P; Zavalova, L L; Pennijainen, V A

    2001-06-01

    Effects of destabilise, bdellin, bdellin A, eglin were investigated in organotypic tissue culture of dorsal root ganglia (DRG) of 10-11-day old chick embryos. Native destabilase and bdellin A, bdellin B and eglin are more active inducing a more intensive neurite growth in DRG as compared with the control. A neurite-stimulating effect of the drug "pyjavit" seems to be associated with destabilase, bdellins and eglin neurite-stimulating activity.

  9. Calretinin-immunoreactive nerves in the uterus, pelvic autonomic ganglia, lumbosacral dorsal root ganglia and lumbosacral spinal cord.

    PubMed

    Papka, R E; Collins, J; Copelin, T; Wilson, K

    1999-10-01

    Nerves containing the calcium-binding protein calretinin have been reported in several organs but not in female reproductive organs and associated ganglia. This study was undertaken to determine if nerves associated with the uterus contain calretinin and the source(s) of calretinin-synthesizing nerves in the rat (are they sensory, efferent, or both?). Calretinin-immunoreactive nerves were present in the uterine horns and cervix where they were associated with arteries, uterine smooth muscle, glands, and the epithelium. Calretinin-immunoreactive terminals were apposed to neurons in the paracervical ganglia; in addition, some postganglionic neurons in this ganglion were calretinin positive. Calretinin perikarya were present in the lumbosacral dorsal root ganglia, no-dose ganglia, and lumbosacral spinal cord. Retrograde axonal tracing, utilizing Fluorogold injected into the uterus or paracervical parasympathetic ganglia, revealed calretinin-positive/Fluorogold-labeled neurons in the dorsal root and nodose ganglia. Also, capsaicin treatment substantially reduced the calretinin-positive fibers in the uterus and pelvic ganglia, thus indicating the sensory nature of these fibers. The presence of calretinin immunoreactivity identifies a subset of nerves that are involved in innervation of the pelvic viscera and have origins from lumbosacral dorsal root ganglia and vagal nodose ganglia. Though the exact function of calretinin in these nerves is not currently known, calretinin is likely to play a role in calcium regulation and their function.

  10. Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury.

    PubMed

    Pei, Bao-An; Zi, Jin-Hua; Wu, Li-Sheng; Zhang, Cun-Hua; Chen, Yun-Zhen

    2015-10-01

    Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 mA and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers.

  11. Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury

    PubMed Central

    Pei, Bao-an; Zi, Jin-hua; Wu, Li-sheng; Zhang, Cun-hua; Chen, Yun-zhen

    2015-01-01

    Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 mA and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers. PMID:26692864

  12. Implanting iodine-125 seeds into rat dorsal root ganglion for neuropathic pain: neuronal microdamage without impacting hind limb motion.

    PubMed

    Jiao, Ling; Zhang, Tengda; Wang, Huixing; Zhang, Wenyi; Fan, Saijun; Huo, Xiaodong; Zheng, Baosen; Ma, Wenting

    2014-06-15

    The use of iodine-125 ((125)I) in cancer treatment has been shown to relieve patients' pain. Considering dorsal root ganglia are critical for neural transmission between the peripheral and central nervous systems, we assumed that (125)I could be implanted into rat dorsal root ganglia to provide relief for neuropathic pain. (125)I seeds with different radioactivity (0, 14.8, 29.6 MBq) were implanted separately through L4-5 and L5-6 intervertebral foramen into the vicinity of the L5 dorsal root ganglion. von Frey hair results demonstrated the mechanical pain threshold was elevated after implanting (125)I seeds from the high radioactivity group. Transmission electron microscopy revealed that nuclear membrane shrinkage, nucleolar margination, widespread mitochondrial swelling, partial vacuolization, lysosome increase, and partial endoplasmic reticulum dilation were visible at 1,440 hours in the low radioactivity group and at 336 hours in the high radioactivity group. Abundant nuclear membrane shrinkage, partial fuzzy nuclear membrane and endoplasmic reticulum necrosis were observed at 1,440 hours in the high radioactivity group. No significant difference in combined behavioral scores was detected between preoperation and postoperation in the low and high radioactivity groups. These results suggested that the mechanical pain threshold was elevated after implanting (125)I seeds without influencing motor functions of the hind limb, although cell injury was present.

  13. Somatostatin and its 2A receptor in dorsal root ganglia and dorsal horn of mouse and human: expression, trafficking and possible role in pain

    PubMed Central

    2014-01-01

    Background Somatostatin (SST) and some of its receptor subtypes have been implicated in pain signaling at the spinal level. In this study we have investigated the role of SST and its sst2A receptor (sst2A) in dorsal root ganglia (DRGs) and spinal cord. Results SST and sst2A protein and sst2 transcript were found in both mouse and human DRGs, sst2A-immunoreactive (IR) cell bodies and processes in lamina II in mouse and human spinal dorsal horn, and sst2A-IR nerve terminals in mouse skin. The receptor protein was associated with the cell membrane. Following peripheral nerve injury sst2A-like immunoreactivity (LI) was decreased, and SST-LI increased in DRGs. sst2A-LI accumulated on the proximal and, more strongly, on the distal side of a sciatic nerve ligation. Fluorescence-labeled SST administered to a hind paw was internalized and retrogradely transported, indicating that a SST-sst2A complex may represent a retrograde signal. Internalization of sst2A was seen in DRG neurons after systemic treatment with the sst2 agonist octreotide (Oct), and in dorsal horn and DRG neurons after intrathecal administration. Some DRG neurons co-expressed sst2A and the neuropeptide Y Y1 receptor on the cell membrane, and systemic Oct caused co-internalization, hypothetically a sign of receptor heterodimerization. Oct treatment attenuated the reduction of pain threshold in a neuropathic pain model, in parallel suppressing the activation of p38 MAPK in the DRGs Conclusions The findings highlight a significant and complex role of the SST system in pain signaling. The fact that the sst2A system is found also in human DRGs and spinal cord, suggests that sst2A may represent a potential pharmacologic target for treatment of neuropathic pain. PMID:24521084

  14. Regulation of the intracellular free calcium concentration in single rat dorsal root ganglion neurones in vitro.

    PubMed Central

    Thayer, S A; Miller, R J

    1990-01-01

    1. Simultaneous whole-cell patch-clamp and Fura-2 microfluorimetric recordings of calcium currents (ICa) and the intracellular free Ca2+ concentration ([Ca2+]i) were made from neurones grown in primary culture from the dorsal root ganglion of the rat. 2. Cells held at -80 mV and depolarized to 0 mV elicited a ICa that resulted in an [Ca2+]i transient which was not significantly buffered during the voltage step and lasted long after the cell had repolarized and the current ceased. The process by which the cell buffered [Ca2+]i back to basal levels could best be described with a single-exponential equation. 3. The membrane potential versus ICa and [Ca2+]i relationship revealed that the peak of the [Ca2+]i transient evoked at a given test potential closely paralleled the magnitude of the ICa suggesting that neither voltage-dependent nor Ca2(+)-induced Ca2+ release from intracellular stores made a significant contribution to the [Ca2+]i transient. 4. When the cell was challenged with Ca2+ loads of different magnitude by varying the duration or potential of the test pulse, [Ca2+]i buffering was more effective for larger Ca2+ loads. The relationship between the integrated ICa and the peak of the [Ca2+]i transient reached an asymptote at large Ca2+ loads indicating that Ca2(+)-dependent processes became more efficient or that low-affinity processes had been recruited. 5. Inhibition of Ca2+ influx with neuropeptide Y demonstrated that inhibition of a large ICa produced minor alterations in the peak of the [Ca2+]i transient, while inhibition of smaller currents produced corresponding decreases in the [Ca2+]i transient. Thus, inhibition of the ICa was reflected by a change in the peak [Ca2+]i only when submaximal Ca2+ loads were applied to the cell, implying that modulation of [Ca2+]i is dependent on the activation state of the cells. 6. Intracellular dialysis with the mitochondrial Ca2+ uptake blocker Ruthenium Red in whole-cell patch-clamp experiments removed the buffering

  15. CYTOLOGICAL STUDIES OF ORGANOTYPIC CULTURES OF RAT DORSAL ROOT GANGLIA FOLLOWING X-IRRADIATION IN VITRO

    PubMed Central

    Masurovsky, Edmund B.; Bunge, Mary Bartlett; Bunge, Richard P.

    1967-01-01

    Under suitable conditions rat dorsal root ganglia differentiate and myelinate in culture, providing an organotypic model of the ganglion (8). Mature cultures of this type were irradiated with a 40 kR dose of 184 kvp X-rays and, after daily observation in the living state, were fixed for light and electron microscopy. Within 24 hr after irradiation, numerous Schwann cells investing unmyelinated axons acutely degenerate. The axons thus denuded display little change. Conversely, few ultrastructural changes develop in Schwann cells investing myelinated axons until after the 4th day. During the 4–14 day period, these Schwann cells and their related myelin sheaths undergo progressive deterioration. Associated axons decrease in diameter but are usually maintained. Myelin deterioration begins as a nodal lengthening and then progresses along two different routes. In intact Schwann cells, fragmentation of myelin begins in a pattern reminiscent of Wallerian degeneration, but its slow breakdown thereafter suggests metabolic disturbances in these Schwann cells. The second pattern of myelin deterioration, occurring after complete degeneration of the related Schwann cell, involves unusual configurational changes in the myelin lamellae. Atypical repeating periods are formed by systematic splitting of lamellae at each major dense line with further splitting at the intraperiod line (Type I) or by splitting in the region of every other intraperiod line (Type II); some sheaths display a compact, wavy, inner zone and an abnormally widened lamellar spacing peripherally (Type III). Extensive blebbing of myelin remnants characterizes the final stages of this extracellular myelin degradation. These observations provide the first description of ultrastructural changes produced by ionizing radiation in nerve fascicles in vitro. PMID:10976235

  16. CYTOLOGICAL STUDIES OF ORGANOTYPIC CULTURES OF RAT DORSAL ROOT GANGLIA FOLLOWING X-IRRADIATION IN VITRO

    PubMed Central

    Masurovsky, Edmund B.; Bunge, Mary Bartlett; Bunge, Richard P.

    1967-01-01

    Long-term organotypic cultures of rat dorsal root ganglia were exposed to a single 40 kR dose of 184 kvp X-rays and studied in the living and fixed states by light or electron microscopy at 1–14 day intervals thereafter. Within the first 4 days following irradiation, over 30% of the neurons display chromatolytic reactions (eccentric nuclei, peripheral dispersal of Nissl substance, central granular zone) as well as abnormal nucleolar changes and dissociation of ribosomes from endoplasmic reticulum cisternae. Some satellite cells undergo retraction or acute degeneration, leaving only basement membrane to cover the neuron in these areas. 8 days after irradiation, neurons also exhibit (a) areas in which ribosomes are substantially reduced, (b) regions of cytoplasmic sequestration, (c) extensive vacuolization of granular endoplasmic reticulum and Golgi complex, and (d) diversely altered mitochondria (including the presence of ribosome-like particles or association with abnormal glycogen and lipid deposits). Nucleolar components become altered or reoriented and may form abnormal projections and ringlike configurations. Sizeable areas of the neuronal soma are now denuded of satellite cells; underlying these areas, nerve processes are found abnormally invaginated into the neuronal cytoplasm. By the 14th day following irradiation, most neurons display marked degenerative changes including extensive regions of ribosome depletion, sequestration, vacuolization, autolysis, and, in some areas, swirls of filaments, myelin figures, and heterogeneous dense bodies. These observations demonstrate that X-irradiation produces profound cytopathological changes in nervous tissue isolated from the host and that many of these changes resemble the effects of radiation on nervous tissue in vivo. PMID:10976234

  17. PKCɛ mediates substance P inhibition of GABAA receptors-mediated current in rat dorsal root ganglion.

    PubMed

    Li, Li; Zhao, Lei; Wang, Yang; Ma, Ke-tao; Shi, Wen-yan; Wang, Ying-zi; Si, Jun-qiang

    2015-02-01

    The mechanism underlying the modulatory effect of substance P (SP) on GABA-activated response in rat dorsal root ganglion (DRG) neurons was investigated. In freshly dissociated rat DRG neurons, whole-cell patch-clamp technique was used to record GABA-activated current and sharp electrode intracellular recording technique was used to record GABA-induced membrane depolarization. Application of GABA (1-1000 μmol/L) induced an inward current in a concentration-dependent manner in 114 out of 127 DRG neurons (89.8 %) examined with whole-cell patch-clamp recordings. Bath application of GABA (1-1000 μmol/L) evoked a depolarizing response in 236 out of 257 (91.8%) DRG neurons examined with intracellular recordings. Application of SP (0.001-1 μmol/L) suppressed the GABA-activated inward current and membrane depolarization. The inhibitory effects were concentration-dependent and could be blocked by the selective neurokinin 1 (NK1) receptors antagonist spantide but not by L659187 and SR142801 (1 μmol/L, n=7), selective antagonists of NK2 and NK3. The inhibitory effect of SP was significantly reduced by the calcium chelator BAPTA-AM, phospholipase C (PLC) inhibitor U73122, and PKC inhibitor chelerythrine, respectively. The PKA inhibitor H-89 did not affect the SP effect. Remarkably, the inhibitory effect of SP on GABA-activated current was nearly completely removed by a selective PKCε inhibitor epilon-V1-2 but not by safingol and LY333531, selective inhibitors of PKCα and PKCβ. Our results suggest that NK1 receptor mediates SP-induced inhibition of GABA-activated current and membrane depolarization by activating intracellular PLC-Ca²⁺-PKCε cascade. SP might regulate the excitability of peripheral nociceptors through inhibition of the "pre-synaptic inhibition" evoked by GABA, which may explain its role in pain and neurogenic inflammation.

  18. Dysregulation of Kv3.4 channels in dorsal root ganglia following spinal cord injury.

    PubMed

    Ritter, David M; Zemel, Benjamin M; Hala, Tamara J; O'Leary, Michael E; Lepore, Angelo C; Covarrubias, Manuel

    2015-01-21

    Spinal cord injury (SCI) patients develop chronic pain involving poorly understood central and peripheral mechanisms. Because dysregulation of the voltage-gated Kv3.4 channel has been implicated in the hyperexcitable state of dorsal root ganglion (DRG) neurons following direct injury of sensory nerves, we asked whether such a dysregulation also plays a role in SCI. Kv3.4 channels are expressed in DRG neurons, where they help regulate action potential (AP) repolarization in a manner that depends on the modulation of inactivation by protein kinase C (PKC)-dependent phosphorylation of the channel's inactivation domain. Here, we report that, 2 weeks after cervical hemicontusion SCI, injured rats exhibit contralateral hypersensitivity to stimuli accompanied by accentuated repetitive spiking in putative DRG nociceptors. Also in these neurons at 1 week after laminectomy and SCI, Kv3.4 channel inactivation is impaired compared with naive nonsurgical controls. At 2-6 weeks after laminectomy, however, Kv3.4 channel inactivation returns to naive levels. Conversely, Kv3.4 currents at 2-6 weeks post-SCI are downregulated and remain slow-inactivating. Immunohistochemistry indicated that downregulation mainly resulted from decreased surface expression of the Kv3.4 channel, as whole-DRG-protein and single-cell mRNA transcript levels did not change. Furthermore, consistent with Kv3.4 channel dysregulation, PKC activation failed to shorten the AP duration of small-diameter DRG neurons. Finally, re-expressing synthetic Kv3.4 currents under dynamic clamp conditions dampened repetitive spiking in the neurons from SCI rats. These results suggest a novel peripheral mechanism of post-SCI pain sensitization implicating Kv3.4 channel dysregulation and potential Kv3.4-based therapeutic interventions.

  19. Dysregulation of Kv3.4 Channels in Dorsal Root Ganglia Following Spinal Cord Injury

    PubMed Central

    Ritter, David M.; Zemel, Benjamin M.; Hala, Tamara J.; O'Leary, Michael E.; Lepore, Angelo C.

    2015-01-01

    Spinal cord injury (SCI) patients develop chronic pain involving poorly understood central and peripheral mechanisms. Because dysregulation of the voltage-gated Kv3.4 channel has been implicated in the hyperexcitable state of dorsal root ganglion (DRG) neurons following direct injury of sensory nerves, we asked whether such a dysregulation also plays a role in SCI. Kv3.4 channels are expressed in DRG neurons, where they help regulate action potential (AP) repolarization in a manner that depends on the modulation of inactivation by protein kinase C (PKC)-dependent phosphorylation of the channel's inactivation domain. Here, we report that, 2 weeks after cervical hemicontusion SCI, injured rats exhibit contralateral hypersensitivity to stimuli accompanied by accentuated repetitive spiking in putative DRG nociceptors. Also in these neurons at 1 week after laminectomy and SCI, Kv3.4 channel inactivation is impaired compared with naive nonsurgical controls. At 2–6 weeks after laminectomy, however, Kv3.4 channel inactivation returns to naive levels. Conversely, Kv3.4 currents at 2–6 weeks post-SCI are downregulated and remain slow-inactivating. Immunohistochemistry indicated that downregulation mainly resulted from decreased surface expression of the Kv3.4 channel, as whole-DRG-protein and single-cell mRNA transcript levels did not change. Furthermore, consistent with Kv3.4 channel dysregulation, PKC activation failed to shorten the AP duration of small-diameter DRG neurons. Finally, re-expressing synthetic Kv3.4 currents under dynamic clamp conditions dampened repetitive spiking in the neurons from SCI rats. These results suggest a novel peripheral mechanism of post-SCI pain sensitization implicating Kv3.4 channel dysregulation and potential Kv3.4-based therapeutic interventions. PMID:25609640

  20. Dorsal Root Ganglionic Field Stimulation Relieves Spontaneous and Induced Neuropathic Pain in Rats.

    PubMed

    Pan, Bin; Yu, Hongwei; Fischer, Gregory J; Kramer, Jeffery M; Hogan, Quinn H

    2016-12-01

    Dorsal root ganglion (DRG) electrical stimulation (ganglionic field stimulation [GFS]) is effective in relieving clinical pain, but its mechanism is unknown. We therefore developed a rat model for GFS to test analgesic effects in the context of neuropathic pain. GFS was applied with a bipolar electrode at L4, using parameters replicating clinical use (20 Hz, 150-μs pulse width, current at 80% of motor threshold). Neuropathic pain was generated by tibial nerve injury (TNI). Pain behavior was monitored by determining the threshold for withdrawal from punctate mechanical stimuli, by identifying hyperalgesic responses to noxious mechanical stimuli, and by hypersensitivity to cold. The affective dimension of pain was measured using conditioned place preference. We found that electrode insertion caused no behavioral evidence of pain and produced no histological evidence of DRG damage. GFS reversed TNI-induced hypersensitivity to cold and mechanical hyperalgesia and allodynia. Allodynia remained diminished 15 minutes after GFS. Conditioned place preference showed that GFS was not rewarding in uninjured control animals but was rewarding in animals subjected to TNI, which reveals analgesic efficacy of GFS for spontaneous pain. We conclude that GFS relieves neuropathic pain in rats. This model may provide a platform for identifying mechanisms and novel applications of GFS. We show that electrical stimulation of the DRG in rats reverses neuropathic pain behavior and provides a rewarding effect to animals with spontaneous neuropathic pain. This confirms analgesic efficacy of DRG stimulation in an animal model, and provides a platform for preclinical exploration. Copyright © 2016 American Pain Society. Published by Elsevier Inc. All rights reserved.

  1. Dorsal root ganglia hypertrophy as in vivo correlate of oxaliplatin-induced polyneuropathy.

    PubMed

    Apostolidis, Leonidas; Schwarz, Daniel; Xia, Annie; Weiler, Markus; Heckel, Andreas; Godel, Tim; Heiland, Sabine; Schlemmer, Heinz-Peter; Jäger, Dirk; Bendszus, Martin; Bäumer, Philipp

    2017-01-01

    To investigate in vivo morphological and functional correlates of oxaliplatin-induced peripheral neuropathy (OXA-PNP) by magnetic resonance neurography (MRN). Twenty patients (7 female, 13 male, 58.9±10.0 years) with mild to moderate OXA-PNP and 20 matched controls (8 female, 12 male, 55.7±15.6 years) were prospectively enrolled. All patients underwent a detailed neurophysiological examination prior to neuroimaging. A standardized imaging protocol at 3.0 Tesla included the lumbosacral plexus and both sciatic nerves and their branches using T2-weighted fat-saturated sequences and diffusion tensor imaging. Quantitative assessment included volumetry of the dorsal root ganglia (DRG), sciatic nerve normalized T2 (nT2) signal and caliber, and fractional anisotropy (FA), mean diffusivity (MD), axial (AD) and radial diffusivity (RD). Additional qualitative evaluation of sciatic, peroneal, and tibial nerves evaluated the presence, degree, and distribution of nerve lesions. DRG hypertrophy in OXA-PNP patients (207.3±47.7mm3 vs. 153.0±47.1mm3 in controls, p = 0.001) was found as significant morphological correlate of the sensory neuronopathy. In contrast, peripheral nerves only exhibited minor morphological alterations qualitatively. Quantitatively, sciatic nerve caliber (27.3±6.7mm2 vs. 27.4±7.4mm2, p = 0.80) and nT2 signal were not significantly changed in patients (1.32±0.22 vs. 1.22±0.26, p = 0.16). AD, RD, and MD showed a non-significant decrease in patients, while FA was unchanged. OXA-PNP manifests with morphological and functional correlates that can be detected in vivo by MRN. We report hypertrophy of the DRG that stands in contrast to experimental and postmortem studies. DRG volume should be further investigated as a biomarker in other sensory peripheral neuropathies and ganglionopathies.

  2. Morphine inhibits acid-sensing ion channel currents in rat dorsal root ganglion neurons.

    PubMed

    Cai, Qi; Qiu, Chun-Yu; Qiu, Fang; Liu, Ting-Ting; Qu, Zu-Wei; Liu, Yu-Min; Hu, Wang-Ping

    2014-03-20

    Extracellular acidosis is a common feature in pain-generating pathological conditions. Acid-sensing ion channels (ASICs), pH sensors, are distributed in peripheral sensory neurons and participate in nociception. Morphine exerts potent analgesic effects through the activation of opioid receptors for various pain conditions. A cross-talk between ASICs and opioid receptors in peripheral sensory neurons has not been shown so far. Here, we have found that morphine inhibits the activity of native ASICs in rat dorsal root ganglion (DRG) neurons. Morphine dose-dependently inhibited proton-gated currents mediated by ASICs in the presence of the TRPV1 inhibitor capsazepine. Morphine shifted the proton concentration-response curve downwards, with a decrease of 51.4±3.8% in the maximum current response but with no significant change in the pH0.5 value. Another μ-opioid receptor agonist DAMGO induced a similar decrease in ASIC currents compared with morphine. The morphine inhibition of ASIC currents was blocked by naloxone, a specific opioid receptor antagonist. Pretreatment of forskolin, an adenylyl cyclase activator, or the addition of cAMP reversed the inhibitory effect of morphine. Moreover, morphine altered acid-evoked excitability of rat DRG neurons and decreased the number of action potentials induced by acid stimuli. Finally, peripheral applied morphine relieved pain evoked by intraplantar of acetic acid in rats. Our results indicate that morphine can inhibit the activity of ASICs via μ-opioid receptor and cAMP dependent signal pathway. These observations demonstrate a cross-talk between ASICs and opioid receptors in peripheral sensory neurons, which was a novel analgesic mechanism of morphine.

  3. Isolated dorsal root ganglion neurones inhibit receptor-dependent adenylyl cyclase activity in associated glial cells

    PubMed Central

    Ng, KY; Yeung, BHS; Wong, YH; Wise, H

    2013-01-01

    Background and Purpose Hyper-nociceptive PGE2 EP4 receptors and prostacyclin (IP) receptors are present in adult rat dorsal root ganglion (DRG) neurones and glial cells in culture. The present study has investigated the cell-specific expression of two other Gs-protein coupled hyper-nociceptive receptor systems: β-adrenoceptors and calcitonin gene-related peptide (CGRP) receptors in isolated DRG cells and has examined the influence of neurone–glial cell interactions in regulating adenylyl cyclase (AC) activity. Experimental Approach Agonist-stimulated AC activity was determined in mixed DRG cell cultures from adult rats and compared with activity in DRG neurone-enriched cell cultures and pure DRG glial cell cultures. Key Results Pharmacological analysis showed the presence of Gs-coupled β2-adrenoceptors and CGRP receptors, but not β1-adrenoceptors, in all three DRG cell preparations. Agonist-stimulated AC activity was weakest in DRG neurone-enriched cell cultures. DRG neurones inhibited IP receptor-stimulated glial cell AC activity by a process dependent on both cell–cell contact and neurone-derived soluble factors, but this is unlikely to involve purine or glutamine receptor activation. Conclusions and Implications Gs-coupled hyper-nociceptive receptors are readily expressed on DRG glial cells in isolated cell cultures and the activity of CGRP, EP4 and IP receptors, but not β2-adrenoceptors, in glial cells is inhibited by DRG neurones. Studies using isolated DRG cells should be aware that hyper-nociceptive ligands may stimulate receptors on glial cells in addition to neurones, and that variable numbers of neurones and glial cells will influence absolute measures of AC activity and affect downstream functional responses. PMID:22924655

  4. Activation of neurotrophins in lumbar dorsal root probably contributes to neuropathic pain after spinal nerve ligation

    PubMed Central

    Kazemi, Abdolreza; Rahmati, Masoud; Eslami, Rasoul; Sheibani, Vahid

    2017-01-01

    Objective(s): Neurotrophins (NTs) exert various effects on neuronal system. Growing evidence indicates that NTs are involved in the pathophysiology of neuropathic pain. However, the exact role of these proteins in modulating nociceptive signaling requires being defined. Thus, the aim of this study was to evaluate the effects of spinal nerve ligation (SNL) on NTs activation in the lumbar dorsal root. Materials and Methods: Ten male Wistar rats were randomly assigned to two groups: tight ligation of the L5 spinal nerve (SNL: n=5) and Sham (n=5). In order to produce neuropathic pain, the L5 spinal nerve was tightly ligated (SNL). Then, allodynia and hyperalgesia tests were conducted weekly. After 4 weeks, tissue samples were taken from the two groups for laboratory evaluations. Here, Real-Time PCR quantity method was used for measuring NTs gene expression levels. Results: SNL resulted in a significant weight loss in the soleus muscle (P<0.05), mechanical allodynia and thermal hyperalgesia thresholds (respectively, P<0.05; P<0.05). Also, NGF, NT-4, NT-3, TrkA, TrkB and TrkC expression were up-regulated following spinal nerve ligation group (respectively, P=0.025, P=0.013, P=0.001, P=0.002, P<0.001, P=001) (respectively, 4.7, 5.2, 7.5, 5.1, 7.2, 6.2 folds). Conclusion: The present study provides new evidence that neuropathic pain induced by spinal nerve ligation probably activates NTs and Trk receptors expression in DRG. However, further studies are needed to better elucidate the role of NTs in a neuropathic pain. PMID:28133521

  5. Propofol up-regulates Mas receptor expression in dorsal root ganglion neurons.

    PubMed

    Cao, Lijun; Xun, Junmei; Jiang, Xinghua; Tan, Rong

    2013-08-01

    Mas is a functional binding site for angiotensin (Ang)-(1-7), a critical component of the renin-angiotensin system that is involved in processing nociceptive information. A recent study reported the localization of Mas in rat dorsal root ganglia (DRG) and demonstrated that Ang-(1-7) produced a dose-dependent peripheral antinociceptive effect in rats through the Mas receptor by an opioid-independent mechanism. In the present study, we for the first time examined the effect of propofol on Mas expression in cultured DRG neurons. We treated rat DRG neurons with propofol at different concentrations (0.1, 0.5, 1, 5 or 10 microM) for different length of time (0.5, 1, 2, 4 or 6 h) with or without transcription inhibitor actinomycin D or different kinase inhibitors. Propofol increased the Mas receptormRNA level in a statistically significant dose- and time-dependent manner within 4 h, which led to dose-dependent up-regulation of the Mas receptor protein level as well as Ang-(1-7) binding on the cell membrane. Actinomycin D (1 mg/ml) and p38 mitogen-activated protein kinase inhibitor PD169316 (25 microM) completely abolished the effect of propofol on Mas receptor expression in DRG neurons. In conclusion, we demonstrate that propofol markedly up-regulates Mas receptor expression at the transcription level in DRG neurons by a p38 MAPK-dependent mechanism. This study provides new insights into the mechanisms of action of propofol in peripheral antinociception, and suggests a new regulatory mechanism on the Ang-(1-7)/Mas axis in the peripheral nervous system.

  6. Chronic nerve injury-induced Mas receptor expression in dorsal root ganglion neurons alleviates neuropathic pain.

    PubMed

    Zhao, Yuanting; Qin, Yue; Liu, Tuanjiang; Hao, Dingjun

    2015-12-01

    Neuropathic pain, which is characterized by hyperalgesia, allodynia and spontaneous pain, is one of the most painful symptoms that can be experienced in the clinic. It often occurs as a result of injury to the peripheral nerves, dorsal root ganglion (DRG), spinal cord or brain. The renin-angiotensin system (RAS) plays an important role in nociception. As an essential component of the RAS, the angiotensin (Ang)-(1-7)/Mas axis may be involved in antinociception. The aim of the present study was to explore the expression pattern of Mas in DRG neurons following chronic nerve injury and examine the effects of Mas inhibition and activation on neuropathic pain in a chronic constriction injury (CCI) rat model. The results showed, that compared with the sham group, CCI caused a time-dependent induction of Mas expression at both the mRNA and the protein levels in DRG neurons. Consistent with the results, isolated DRG neurons showed a time-dependent increase in Ang-(1-7) binding on the cell membrane following the CCI surgery, but not the sham surgery. Compared with the sham control groups, CCI significantly decreased the paw withdrawal latency and threshold, and this was markedly improved and aggravated by intrathecal injection of the selective Mas agonist Ang-(1-7) and the selective Mas inhibitor D-Pro7-Ang-(1-7), respectively. In conclusion, this study has provided the first evidence, to the best of our knowledge, that the Mas expression in DRG neurons is time-dependently induced by chronic nerve injury and that the intrathecal activation and inhibition of Mas can improve and aggravate CCI-induced neuropathic pain, respectively. This study has provided novel insights into the pathophysiological process of neuropathic pain and suggests that the Ang-(1-7)/Mas axis could be an effective therapeutic target for neuropathic pain, warranting further study.

  7. Protons activate a cation conductance in a sub-population of rat dorsal root ganglion neurones.

    PubMed Central

    Bevan, S; Yeats, J

    1991-01-01

    1. The responses of adult and neonatal rat dorsal root ganglion (DRG) neurones to buffered acidic solutions were studied with both voltage clamp and radioactive ion flux techniques. Electrophysiological experiments were made on acutely isolated neurones and ion flux experiments were made on cells that had been in culture for 3-6 days. 2. Acid solutions of pH < 6.2 evoked a sustained, slowly inactivating inward current in neurones voltage clamped at negative holding potentials. The size of the current increased with increasing proton concentrations. This response was restricted to a sub-population (approximately 45%) of adult and neonatal rat DRG neurones and was distinct from a rapidly activating and inactivating proton-induced inward sodium current that was also found in DRG neurones. 3. The proton-activated sustained current was due to an increase in cation conductance that allowed K+, Cs+ and Na+ to pass with PK/PNa = 1.32 and PCs/PNa = 1.12. 4. Radioactive ion efflux experiments made on neonatal rat cultured DRG neurones showed that protons also increased the permeability to both [14C]guanidinium and 86Rb+ ions. The half-maximal increase in efflux rate for 86Rb+ occurred at pH 5.8. Acid solution also stimulated the efflux of 86Rb+ in cultures of adult rat neurones. 5. Cells that showed a late, sustained proton-activated current also responded to capsaicin. In addition, no proton-activated fluxes of either [14C]guanidinium or 86Rb+ ions were observed in cultures of DRG neurones that had been treated with high concentrations of capsaicin (10 microM) to kill the capsaicin-sensitive neurones. Thus this proton-activated current is restricted largely, if not exclusively, to capsaicin-sensitive peripheral sensory neurones. PMID:1726795

  8. Characteristics of GABA-activated chloride channels in mammalian dorsal root ganglion neurones.

    PubMed

    Robertson, B

    1989-04-01

    1. The properties of gamma-aminobutyric acid (GABA)-activated chloride channels in dorsal root ganglion (DRG) neurones obtained from rats and cats were examined using the single-electrode voltage clamp in conjunction with suction-electrode techniques. 2. GABA-evoked currents showed voltage-sensitive kinetics. Time constants (tau D) were measured from voltage-jump relaxations and tau D became briefer with membrane hyperpolarization. tau D was 33 ms at -120 mV with 60 microM-GABA and changed e-fold for 188 mV. tau D decreased as GABA concentration was increased - the extrapolated tau D at 'zero' GABA concentration was approximately equal to 50 ms at -120 mV. 3. The steady-state current in GABA was curvilinear, rectifying at negative potentials. The instantaneous current was linear with symmetrical chloride concentrations (140 mM) on both sides of the cell membrane. 4. Muscimol was a more effective agonist than GABA, while piperidine-4-sulphonic acid and ethylenediamine monocarbamate were only weakly effective agonists. Taurine and glycine had no detectable agonist activity. 5. Ion substitution experiments revealed the permeability sequence I- greater than Br- greater than Cl- greater than F- greater than propionate (1.88 greater than 1.21 greater than 1.0 approximately equal to 0.1 approximately equal to 0.1). 6. The presence of iodide and bromide ions externally caused an increase in chloride efflux at membrane potentials more negative than -40 mV, and caused a prolongation of voltage-jump relaxations. Relaxations in fluoride and propionate solutions were faster than those seen in chloride.

  9. Inhibition by morphine and its analogs of action potentials in adult rat dorsal root ganglion neurons.

    PubMed

    Mizuta, Kotaro; Fujita, Tsugumi; Kumamoto, Eiichi

    2012-09-01

    Although opioids inhibit action potential (AP) conduction in primary-afferent fibers, this has not yet been fully examined. We investigated by using the sharp glass microelectrode technique how opioids (morphine, codeine, and ethylmorphine) affect APs recorded from adult rat dorsal root ganglion (DRG) neurons in response to sciatic nerve stimulation. The DRG neurons were classified into three types, Aα/β, Aδ, and C, according to AP characteristics, including the fiber conduction velocity (CV) of the neuron. AP of the Aα/β neuron was reduced in peak amplitude by each of the opioids in a reversible and concentration-dependent manner. The potency sequence was ethylmorphine > codeine = morphine (IC(50) = 0.70, 2.5, and 2.9 mM, respectively), indicating that this AP inhibition is related to the chemical structure of the opioid. Each of the Aδ and C neuron APs was also inhibited by the opioids; ethylmorphine had a tendency to inhibit APs more effectively than codeine and morphine. This inhibition was variable in extent among neurons and was either comparable to or greater than that of the Aα/β neuron AP. The opioid-induced AP inhibitions were unaffected by nonspecific opioid-receptor antagonist naloxone; opioid-receptor agonists did not affect APs. In conclusion, the opioids inhibited APs in DRG neurons without opioid-receptor activation; this inhibition was different among neurons having different primary-afferent fiber CVs and also among the three kinds of opioid. The inhibition by opioid of primary-afferent fiber AP conduction is suggested to be distinct in extent among fibers conveying distinct types of nociceptive information. Copyright © 2012 Wiley Periodicals, Inc.

  10. Cutaneous inflammation regulates THIK1 expression in small C-like nociceptor dorsal root ganglion neurons.

    PubMed

    Haskins, William; Benitez, Sergio; Mercado, Juan M; Acosta, Cristian G

    2017-09-01

    Tandem pore-domain Halothane Inhibited K(+) channel (THIK1) is a two-pore-domain potassium channel (K2P) present in dorsal root ganglia (DRG). We previously demonstrated that THIK1 mRNA levels in the DRG dropped ipsilaterally 1day after CFA-induced cutaneous inflammation (CFA1). In this study we aimed to identify the currently unknown DRG subpopulations expressing THIK1, and to investigate the relationship between the channel and both inflammatory and spontaneous pain in normal rats. Using a combination of immunohistochemistry, western blotting and behavioural tests, we found that all small neurons and large groups of medium and large DRG neurons express THIK1. Myelinated and unmyelinated fibers, nerve endings in the skin and lamina I and II of the spinal cord also express the channel. THIK1 staining co-localizes with IB4-binding and trkA suggesting that the channel is expressed by nociceptors. At CFA1, both cytoplasmic and edge (membrane-associated) THIK1 staining were significantly reduced only in small neurons ipsilaterally compared to normal. At 4days after inflammation (CFA4), edge THIK1 staining levels in small neurons decreased bilaterally compared to normal. Medium and large size DRG neurons showed no change in THIK1 expression either at CFA1 or CFA4. Ipsilateral (but not contralateral) mean %intensities of THIK1 in small neurons at CFA1 correlated strongly negatively with spontaneous foot lifting (SFL) duration (a marker of spontaneous pain). Thus, nociceptors express THIK1 that can be regulated by cutaneous inflammation. Finally, in vivo siRNA knockdown of THIK1 resulted in longer SFL duration than siRNA scramble-treated rats. Taken together our evidence suggests a potential involvement for THIK1 in pain processing following inflammation. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Gap junctions in dorsal root ganglia: possible contribution to visceral pain.

    PubMed

    Huang, Tian-Ying; Belzer, Vitali; Hanani, Menachem

    2010-01-01

    Peripheral injuries can lead to sensitization of neurons in dorsal root ganglia (DRGs), which can contribute to chronic pain. The neurons are sensitized by a combination of physiological and biochemical changes, whose full details are still obscure. Another cellular element in DRGs are satellite glial cells (SGCs), which surround the neurons, but little is known about their role in nociception. We investigated the contribution of SGCs to neuronal sensitization in isolated S1 DRGs from a mouse model of colonic inflammation induced by local application of dinitrosulfonate benzoate (DNBS). Retrograde labeling was used to identify DRG neurons projecting to the colon. Cell-to-cell coupling was determined by intracellular dye injection, and the electrical properties of the neurons were studied with intracellular electrodes. Pain behavior was assessed with von-Frey hairs. The dye injections showed that 10-12 days after DNBS application there was a 6.6-fold increase in gap junction-mediated coupling between SGCs surrounding adjacent neurons, and this occurred preferentially (another 2-fold increase) near neurons that project to the colon. Neuron-neuron coupling incidence increased from 0.7% to 12.1% by colonic inflammation. Inflammation led to an augmented neuronal excitability, and to a reduced pain threshold. Gap junction blockers abolished the inflammation-induced changes in SGCs and neurons, and significantly reversed the pain behavior. We propose that inflammation induces augmented cell coupling in DRGs that contributes to neuronal hyperexcitability, which in turn leads to visceral pain. Gap junction blockers may have potential as analgesic drugs.

  12. Dye coupling among satellite glial cells in mammalian dorsal root ganglia.

    PubMed

    Huang, Tian-Ying; Cherkas, Pavel S; Rosenthal, David W; Hanani, Menachem

    2005-03-02

    Dorsal root ganglia (DRG) are key elements in sensory signaling under physiological and pathological conditions. Little is known about electrical coupling among cells in these ganglia. In this study, we injected the fluorescent dye Lucifer yellow (LY) into single cells to examine dye coupling in DRG. We found no dye coupling between neurons or between neurons and their attendant satellite glial cells (SGCs). In mouse DRG, we observed that in 26.2% of the cases SGCs that surround a given neuron were dye coupled. In only 3.2% of the cases SGCs that make envelopes around different neurons were coupled. The data from mouse ganglia were very similar to those from rat and guinea pig DRG. The results obtained by injection of the tracer biocytin were very similar to those observed with LY. The coupling incidence within the envelopes increased 3.1-fold by high extracellular pH (8.0), but coupling between envelopes was not affected. Acidic pH (6.8) reduced the coupling. High extracellular K+ (9.4 mM) increased the coupling 2.4-fold and 4.7-fold within and between envelopes, respectively. Low extracellular Ca2+ (0.5, 1.0 mM) partly reversed the effect of high K+ on coupling. The results showed that SGCs in mammalian sensory ganglia are connected by gap junctions. This coupling is very sensitive to changes in pH, and can therefore be modulated under various physiological and pathological conditions. The dependence of the coupling on extracellular K+ and Ca2+ suggests that the permeability of gap junctions can be altered by physiological and pharmacological stimuli.

  13. Morphological and electrophysiological changes in mouse dorsal root ganglia after partial colonic obstruction.

    PubMed

    Huang, Tian-Ying; Hanani, Menachem

    2005-10-01

    There is evidence that sensitization of neurons in dorsal root ganglia (DRG) may contribute to pain induced by intestinal injury. We hypothesized that obstruction-induced pain is related to changes in DRG neurons and satellite glial cells (SGCs). In this study, partial colonic obstruction was induced by ligation. The neurons projecting to the colon were traced by an injection of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate into the colon wall. The electrophysiological properties of DRG neurons were determined using intracellular electrodes. Dye coupling was examined with an intracellular injection of Lucifer yellow (LY). Morphological changes in the colon and DRG were examined. Pain was assessed with von Frey hairs. Partial colonic obstruction caused the following changes. First, coupling between SGCs enveloping different neurons increased 18-fold when LY was injected into SGCs near neurons projecting to the colon. Second, neurons were not coupled to other neurons or SGCs. Third, the firing threshold of neurons projecting to the colon decreased by more than 40% (P < 0.01), and the resting potential was more positive by 4-6 mV (P < 0.05). Finally, the number of neurons displaying spontaneous spikes increased eightfold, and the number of neurons with subthreshold voltage oscillations increased over threefold. These changes are consistent with augmented neuronal excitability. The pain threshold to abdominal stimulation decreased by 70.2%. Inflammatory responses were found in the colon wall. We conclude that obstruction increased neuronal excitability, which is likely to be a major factor in the pain behavior observed. The augmented dye coupling between glial cells may contribute to the neuronal hyperexcitability.

  14. Increased response to glutamate in small diameter dorsal root ganglion neurons after sciatic nerve injury.

    PubMed

    Gong, Kerui; Kung, Ling-Hsuan; Magni, Giulia; Bhargava, Aditi; Jasmin, Luc

    2014-01-01

    Glutamate in the peripheral nervous system is involved in neuropathic pain, yet we know little how nerve injury alters responses to this neurotransmitter in primary sensory neurons. We recorded neuronal responses from the ex-vivo preparations of the dorsal root ganglia (DRG) one week following a chronic constriction injury (CCI) of the sciatic nerve in adult rats. We found that small diameter DRG neurons (<30 µm) exhibited increased excitability that was associated with decreased membrane threshold and rheobase, whereas responses in large diameter neurons (>30 µm) were unaffected. Puff application of either glutamate, or the selective ionotropic glutamate receptor agonists alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainic acid (KA), or the group I metabotropic receptor (mGluR) agonist (S)-3,5-dihydroxyphenylglycine (DHPG), induced larger inward currents in CCI DRGs compared to those from uninjured rats. N-methyl-D-aspartate (NMDA)-induced currents were unchanged. In addition to larger inward currents following CCI, a greater number of neurons responded to glutamate, AMPA, NMDA, and DHPG, but not to KA. Western blot analysis of the DRGs revealed that CCI resulted in a 35% increase in GluA1 and a 60% decrease in GluA2, the AMPA receptor subunits, compared to uninjured controls. mGluR1 receptor expression increased by 60% in the membrane fraction, whereas mGluR5 receptor subunit expression remained unchanged after CCI. These results show that following nerve injury, small diameter DRG neurons, many of which are nociceptive, have increased excitability and an increased response to glutamate that is associated with changes in receptor expression at the neuronal membrane. Our findings provide further evidence that glutamatergic transmission in the periphery plays a role in nociception.

  15. Dorsal root ganglion myeloid zinc finger protein 1 contributes to neuropathic pain after peripheral nerve trauma.

    PubMed

    Li, Zhisong; Gu, Xiyao; Sun, Linlin; Wu, Shaogen; Liang, Lingli; Cao, Jing; Lutz, Brianna Marie; Bekker, Alex; Zhang, Wei; Tao, Yuan-Xiang

    2015-04-01

    Peripheral nerve injury-induced changes in gene transcription and translation in primary sensory neurons of the dorsal root ganglion (DRG) are considered to contribute to neuropathic pain genesis. Transcription factors control gene expression. Peripheral nerve injury increases the expression of myeloid zinc finger protein 1 (MZF1), a transcription factor, and promotes its binding to the voltage-gated potassium 1.2 (Kv1.2) antisense (AS) RNA gene in the injured DRG. However, whether DRG MZF1 participates in neuropathic pain is still unknown. Here, we report that blocking the nerve injury-induced increase of DRG MZF1 through microinjection of MZF1 siRNA into the injured DRG attenuated the initiation and maintenance of mechanical, cold, and thermal pain hypersensitivities in rats with chronic constriction injury (CCI) of the sciatic nerve, without affecting locomotor functions and basal responses to acute mechanical, heat, and cold stimuli. Mimicking the nerve injury-induced increase of DRG MZF1 through microinjection of recombinant adeno-associated virus 5 expressing full-length MZF1 into the DRG produced significant mechanical, cold, and thermal pain hypersensitivities in naive rats. Mechanistically, MZF1 participated in CCI-induced reductions in Kv1.2 mRNA and protein and total Kv current and the CCI-induced increase in neuronal excitability through MZF1-triggered Kv1.2 AS RNA expression in the injured DRG neurons. MZF1 is likely an endogenous trigger of neuropathic pain and might serve as a potential target for preventing and treating this disorder.

  16. Intracellular calcium regulation among subpopulations of rat dorsal root ganglion neurons

    PubMed Central

    Lu, Shao-Gang; Zhang, Xiulin; Gold, Michael S

    2006-01-01

    Primary afferent neurons are functionally heterogeneous. To determine whether this functional heterogeneity reflects, in part, heterogeneity in the regulation of the concentration of intracellular Ca2+ ([Ca2+]i), the magnitude and decay of evoked Ca2+ transients were assessed in subpopulations of dorsal root ganglion (DRG) neurons with voltage clamp and fura-2 ratiometric imaging. To determine whether differences in evoked Ca2+ transients among subpopulations of DRG neurons reflected differences in the contribution of Ca2+ regulatory mechanisms, pharmacological techniques were employed to assess the contribution of influx, efflux, release and uptake pathways. Subpopulations of DRG neurons were defined by cell body size, binding of the plant lectin IB4 and responsiveness to the algogenic compound capsaicin (CAP). Ca2+ transients were evoked with 30 mm K+ or voltage steps to 0 mV. There were marked differences between subpopulations of neurons with respect to both the magnitude and decay of the Ca2+ transient, with the largest and most slowly decaying Ca2+ transients in small-diameter, IB4-positive, CAP-responsive neurons. The smallest and most rapidly decaying transients were in large-diameter, IB4-negative and CAP-unresponsive DRG neurons. These differences were not due to a differential distribution of voltage-gated Ca2+ currents. However, these differences did appear to reflect a differential contribution of other influx, efflux, release and uptake mechanisms between subpopulations of neurons. These results suggest that electrical activity in subpopulations of DRG neurons will have a differential influence on Ca2+-regulated phenomena such as spike adaptation, transmitter release and gene transcription. Significantly more activity should be required in large-diameter non-nociceptive afferents than in small-diameter nociceptive afferents to have a comparable influence on these processes. PMID:16945973

  17. Runx3-regulated expression of two Ntrk3 transcript variants in dorsal root ganglion neurons.

    PubMed

    Ogihara, Yuuki; Masuda, Tomoyuki; Ozaki, Shigeru; Yoshikawa, Masaaki; Shiga, Takashi

    2016-03-01

    Somatosensation is divided into proprioception and cutaneous sensation. Dorsal root ganglion (DRG) neurons project their fibers toward peripheral targets including muscles and skin, and centrally to the spinal cord. Proprioceptive DRG neurons transmit information from muscle spindles and Golgi tendon organs to the spinal cord. We previously showed that Runt-related transcription factor 3 (Runx3) is expressed in these neurons and their projections to the ventral spinal cord and muscle spindles are lost in Runx3-deficient (Runx3(-/-) ) mouse embryos. Although Runx3 is likely to contribute to the fate decision and projection of proprioceptive DRG neurons, the precise roles for Runx3 in these phenomena are unknown. To identify genes regulated by Runx3 in embryonic DRGs, we performed microarray analyses using cDNAs isolated from wild-type and Runx3(-/-) DRGs of embryonic day (E) 12.5 and selected two transcript variants of the tyrosine kinase receptor C (TrkC) gene. These variants, Ntrk3 variant 1 (Ntrk3-v1) and variant 2 (Ntrk3-v2), encode full-length and truncated receptors of neurotrophin-3, respectively. Using double in situ hybridization, we found that most of Ntrk3-v1 mRNA expression in E14.5 DRGs depended on Runx3 but that more than half of Ntrk3-v2 mRNA one were expressed in a Runx3-independent manner. Furthermore, our data revealed that the rate of Ntrk3-v1 and Ntrk3-v2 colocalization in DRGs changed from E14.5 to E18.5. Together, our data suggest that Runx3 may play a crucial role in the development of DRGs by regulating the expression of Ntrk3 variants and that DRG neurons expressing Ntrk3-v1 but not Ntrk3-v2 may differentiate into proprioceptive ones.

  18. Downregulation of miR-210 protected bupivacaine-induced neurotoxicity in dorsal root ganglion.

    PubMed

    Wang, Yiheng; Ni, Hongxia; Zhang, Wenrui; Wang, Xiu; Zhang, Haishan

    2016-04-01

    Local anesthetic may cause neurotoxicity in developing neurons. In this study, we examined the molecular mechanisms of microRNA-210 (miR-210) in regulating bupivacaine-induced dorsal root ganglia (DRG) neurotoxicity in vitro. Young mouse (P30) DRG explants were cultured in vitro and treated with 5 mM bupivacaine to induce neurotoxicity. QRT-PCR was used to evaluate the expression profiles of miRNAs within 24 h after bupivacaine treatment. MiR-210 was downregulated in DRG, and its effects on bupivacaine-induced neurotoxicity were evaluated by apoptosis and neurite growth assays, respectively. Putative downstream target of miR-210 in DRG, BDNF, was evaluated by dual-luciferase assay, qRT-PCR, and western blot, respectively. BDNF was then knocked down by siRNA to assess its associated effects in regulating DRG neurotoxicity. Within the initial 24 h after bupivacaine treatment, various patterns of miRNA expression were observed, whereas miR-210 was constantly upregulated. Application of miR-210 inhibitor efficiently downregulated endogenous miR-210, protected apoptosis and neurite retraction in bupivacaine damaged DRG neurons. Using dual-luciferase assay, qRT-PCR, and western blot, BDNF was confirmed to the downstream target of miR-210 in DRG. SiRNA-mediated BDNF downregulation reversed the effect of miR-210 downregulation in DRG neurotoxicity. MiR-210, through the regulation of BDNF, plays important role in anesthetics-induced DRG neurotoxicity.

  19. Differential effects of muscimol upon the firing frequency of large and small amplitude antidromic dorsal root action potentials in rat spinal cord in vitro.

    PubMed

    Bagust, J; Willis, W D

    2002-09-20

    The effects of bath applied muscimol upon spontaneous and evoked antidromic activity recorded from lumbar dorsal roots was investigated in hemisected, isolated preparations of rat spinal cord. In magnesium free medium containing 0.1 microM 4-aminopyridine, bursts of high amplitude (up to 1 mV), dorsal root reflexes were recorded. These were blocked by low concentrations of muscimol (2-5 microM). Higher concentrations (5-20 microM) of muscimol caused a concentration-dependent increase in the frequency of small amplitude (<200 microV) spontaneous dorsal root action potentials. The possibility that the large and small amplitude extracellular action potentials reflect activity in large and small diameter dorsal root axons, and that these respond in different ways to the GABA(A) agonist muscimol, is discussed.

  20. Case report: successful epiradicular peripheral nerve stimulation of the C2 dorsal root ganglion for postherpetic neuralgia.

    PubMed

    Lynch, Paul J; McJunkin, Tory; Eross, Eric; Gooch, Stacie; Maloney, Jillian

    2011-01-01

    Postherpetic neuralgia (PHN) is the most common complication following an acute varicella zoster virus infection. PHN often results in a chronic severe pain condition refractory to conservative pain management treatments. Peripheral nerve stimulation over the affected spinal nerve root may be an effective treatment option for patients with intractable PHN. To describe a successful case of peripheral nerve stimulation of the second cervical dorsal root ganglion for the treatment of intractable PHN. An 80-year-old man with a 15-month history of severe PHN was referred to our clinic for pain management. His pain was localized to the left side in the distribution of the C2 dermatome. The patient's pain was unresponsive to comprehensive conventional treatments for PHN including physical therapy, membrane stabilizing medications, opioids, anti-inflammatories, cervical epidural steroid injections, cervical facet joint injections, and dorsal root ganglion blockade with pulsed radiofrequency. After failing to respond to conservative and interventional therapies, a peripheral nerve stimulator trial was conducted for a period of seven days. The lead was placed within the epidural space over the atlanto-axial joint under fluoroscopy to stimulate the left C2 nerve root. This trial resulted in a significant decrease of the patient's pain, and discontinuation of all pain medications. We describe a case of successful electrode placement at the C2 spinal level for the treatment of refractory PHN. © 2010 International Neuromodulation Society.

  1. Confocal imaging reveals three-dimensional fine structure difference between ventral and dorsal nerve roots

    NASA Astrophysics Data System (ADS)

    Wu, Yuxiang; Sui, Tao; Cao, Xiaojian; Lv, Xiaohua; Zeng, Shaoqun; Sun, Peng

    2011-05-01

    Peripheral nerve injury repair is one of the most challenging problems in neurosurgery, partially due to lack of knowledge of three-dimensional (3-D) fine structure and organization of peripheral nerves. In this paper, we explored the structures of nerve fibers in ventral and dorsal nerves with a laser scanning confocal microscopy. Thick tissue staining results suggested that nerve fibers have a different 3-D structure in ventral and dorsal nerves, and reconstruction from serial sectioning images showed that in ventral nerves the nerve fibers travel in a winding form, while in dorsal nerves, the nerve fibers form in a parallel cable pattern. These structural differences could help surgeons to differentiate ventral and dorsal nerves in peripheral nerve injury repair, and also facilitate scientists to get a deeper understanding about nerve fiber organization.

  2. Confocal imaging reveals three-dimensional fine structure difference between ventral and dorsal nerve roots.

    PubMed

    Wu, Yuxiang; Sui, Tao; Cao, Xiaojian; Lv, Xiaohua; Zeng, Shaoqun; Sun, Peng

    2011-05-01

    Peripheral nerve injury repair is one of the most challenging problems in neurosurgery, partially due to lack of knowledge of three-dimensional (3-D) fine structure and organization of peripheral nerves. In this paper, we explored the structures of nerve fibers in ventral and dorsal nerves with a laser scanning confocal microscopy. Thick tissue staining results suggested that nerve fibers have a different 3-D structure in ventral and dorsal nerves, and reconstruction from serial sectioning images showed that in ventral nerves the nerve fibers travel in a winding form, while in dorsal nerves, the nerve fibers form in a parallel cable pattern. These structural differences could help surgeons to differentiate ventral and dorsal nerves in peripheral nerve injury repair, and also facilitate scientists to get a deeper understanding about nerve fiber organization.

  3. The vascular pattern of the human dorsal root ganglion and its probable bearing on a compartment syndrome.

    PubMed

    Parke, Wesley Wilkin; Whalen, Joseph Leo

    2002-02-15

    A descriptive anatomic investigation of the vasculature of the dorsal root ganglions. To determine whether the blood supply of the various spinal ganglions is sufficiently consistent to derive a "generic" description and illustration that would be applicable to all spinal levels, and to ascertain whether this vascular pattern is inherently predisposed to the development of a closed compartment syndrome. The few previous descriptions of spinal ganglionic vasculature do not include photographic evidence showing uniformity in the arterial distribution plan at all ganglionic levels. The venous drainage, although verbally reconstructed from microscopic sections, lacks any indication of its probable role in the etiology of a compartment syndrome. Three perinatal cadavers received latex/India ink injections, and their removed radiculomedullary systems were cleared, transilluminated, and macroscopically photographed. Paravertebral sections were grossly removed from the spines of two adult anatomic cadavers and received retrograde venous injections of a fine suspension of barium sulfate. The intervertebral foraminal tissues were then dissected from the bone, and radiographs of them were made. For comparative reference, a nerve root/ganglion complex of a rabbit was arterially injected with a more dilute preparation of the latex/India ink suspension. Macroscopic photographs of perinatal dorsal root ganglions showed that the pattern of the intraganglionic arterial distribution was sufficiently consistent to allow a graphic rendering and labeling of a "generic" ganglion. The series of incomplete retrograde venous injections adequately indicated the pressure labile location of a periganglionic venous plexus. The common development, structure, and function of the human dorsal root ganglions have resulted in the evolution of a uniform nutritional vascular pattern that can be conceptualized in a single visual image. Its plan of a primarily internal arterialization with a

  4. Yiqi Huayu recipe relieves nerve root constriction induced radicular neuralgia by down-regulating TRPV4 expression in dorsal root ganglion

    PubMed Central

    Tang, Zhanying; Cui, Xuejun; Hu, Zhijun; Xiao, Jing; Li, Weiwei; Yang, Qiangling; Liu, Dan; Lin, Jie; Wang, Yongjun; Shi, Qi

    2015-01-01

    The aim of this study was to observe the effects of Yiqi Huayu recipe on TRPV4 expression in radicular neuralgia model induced by chronic constriction to the rat lumber nerve root. Healthy male SD rats were divided into 3 groups for radicular neuralgia (RN) model construction: the sham operation group, model groups (day 3, 7, 14 and 28), and medication groups (day 3, 7, 14 and 28). Von-Frey hairs test was performed to detect the 50% with drawal threshold (50% TPW) for rats of each group. The expression of TRPV4 in dorsal root ganglion was detected at both mRNA and protein level. Rats from all model groups displayed hyperalgesia with significantly reduced 50% TPW values compared with sham-operation group (P<0.01); Yiqi Huayu recipe medication groups showed higher 50% TPW than model group since 7 days post medication (P<0.01); the medication groups showed decreased TRPV4 expression than that of model groups (P<0.01). In conclusion, Yiqi Huayu recipe alleviates nerve root constriction induced radicular neuralgia by repressing TRPV4 expression in dorsal root ganglion. PMID:26770465

  5. Chronic recruitment of primary afferent neurons by microstimulation in the feline dorsal root ganglia

    NASA Astrophysics Data System (ADS)

    Fisher, Lee E.; Ayers, Christopher A.; Ciollaro, Mattia; Ventura, Valérie; Weber, Douglas J.; Gaunt, Robert A.

    2014-06-01

    Objective. This study describes results of primary afferent neural microstimulation experiments using microelectrode arrays implanted chronically in the lumbar dorsal root ganglia (DRG) of four cats. The goal was to test the stability and selectivity of these microelectrode arrays as a potential interface for restoration of somatosensory feedback after damage to the nervous system such as amputation. Approach. A five-contact nerve-cuff electrode implanted on the sciatic nerve was used to record the antidromic compound action potential response to DRG microstimulation (2-15 µA biphasic pulses, 200 µs cathodal pulse width), and the threshold for eliciting a response was tracked over time. Recorded responses were segregated based on conduction velocity to determine thresholds for recruiting Group I and Group II/Aβ primary afferent fibers. Main results. Thresholds were initially low (5.1 ± 2.3 µA for Group I and 6.3 ± 2.0 µA for Group II/Aβ) and increased over time. Additionally the number of electrodes with thresholds less than or equal to 15 µA decreased over time. Approximately 12% of tested electrodes continued to elicit responses at 15 µA up to 26 weeks after implantation. Higher stimulation intensities (up to 30 µA) were tested in one cat at 23 weeks post-implantation yielding responses on over 20 additional electrodes. Within the first six weeks after implantation, approximately equal numbers of electrodes elicited only Group I or Group II/Aβ responses at threshold, but the relative proportion of Group II/Aβ responses decreased over time. Significance. These results suggest that it is possible to activate Group I or Group II/Aβ primary afferent fibers in isolation with penetrating microelectrode arrays implanted in the DRG, and that those responses can be elicited up to 26 weeks after implantation, although it may be difficult to achieve a consistent response day-to-day with currently available electrode technology. The DRG are compelling targets

  6. Mu opioid receptor-effector coupling and trafficking in dorsal root ganglia neurons.

    PubMed

    Walwyn, W M; Wei, W; Xie, C-W; Chiu, K; Kieffer, B L; Evans, C J; Maidment, N T

    2006-10-13

    Morphine induces profound analgesic tolerance in vivo despite inducing little internalization of the mu opioid receptor (muOR). Previously proposed explanations suggest that this lack of internalization could either lead to prolonged signaling and associated compensatory changes in downstream signaling systems, or that the receptor is unable to recycle and resensitize and so loses efficacy, either mechanism resulting in tolerance. We therefore examined, in cultured neurons, the relationship between muOR internalization and desensitization in response to two agonists, D-Ala2, N-MePhe4, Gly5-ol-enkephalin (DAMGO) and morphine. In addition, we studied the chimeric mu/delta opioid receptor (mu/ partial differentialOR) which could affect internalization and desensitization in neurons. Dorsal root ganglia neurons from muOR knockout mice were transduced with an adenovirus expressing either receptor and their respective internalization, desensitization and trafficking profiles determined. Both receptors desensitized equally, measured by Ca2+ current inhibition, during the first 5 min of agonist exposure to DAMGO or morphine treatment, although the mu/partial differentialOR desensitized more extensively. Such rapid desensitization was unrelated to internalization as DAMGO, but not morphine, internalized both receptors after 20 min. In response to DAMGO the mu/partial differentialOR internalized more rapidly than the muOR and was trafficked through Rab4-positive endosomes and lysosomal-associated membrane protein-1-labeled lysosomes whereas the muOR was trafficked through Rab4 and Rab11-positive endosomes. Chronic desensitization of the Ca2+ current response, after 24 h of morphine or DAMGO incubation, was seen in the DAMGO, but not morphine-treated, muOR-expressing cells. Such persistence of signaling after chronic morphine treatment suggests that compensation of downstream signaling systems, rather than loss of efficacy due to poor receptor recycling, is a more likely

  7. Genetic study of axon regeneration with cultured adult dorsal root ganglion neurons.

    PubMed

    Saijilafu; Zhou, Feng-Quan

    2012-08-17

    It is well known that mature neurons in the central nervous system (CNS) cannot regenerate their axons after injuries due to diminished intrinsic ability to support axon growth and a hostile environment in the mature CNS(1,2). In contrast, mature neurons in the peripheral nervous system (PNS) regenerate readily after injuries(3). Adult dorsal root ganglion (DRG) neurons are well known to regenerate robustly after peripheral nerve injuries. Each DRG neuron grows one axon from the cell soma, which branches into two axonal branches: a peripheral branch innervating peripheral targets and a central branch extending into the spinal cord. Injury of the DRG peripheral axons results in substantial axon regeneration, whereas central axons in the spinal cord regenerate poorly after the injury. However, if the peripheral axonal injury occurs prior to the spinal cord injury (a process called the conditioning lesion), regeneration of central axons is greatly improved(4). Moreover, the central axons of DRG neurons share the same hostile environment as descending corticospinal axons in the spinal cord. Together, it is hypothesized that the molecular mechanisms controlling axon regeneration of adult DRG neurons can be harnessed to enhance CNS axon regeneration. As a result, adult DRG neurons are now widely used as a model system to study regenerative axon growth(5-7). Here we describe a method of adult DRG neuron culture that can be used for genetic study of axon regeneration in vitro. In this model adult DRG neurons are genetically manipulated via electroporation-mediated gene transfection(6,8). By transfecting neurons with DNA plasmid or si/shRNA, this approach enables both gain- and loss-of-function experiments to investigate the role of any gene-of-interest in axon growth from adult DRG neurons. When neurons are transfected with si/shRNA, the targeted endogenous protein is usually depleted after 3-4 days in culture, during which time robust axon growth has already occurred

  8. Nicotinic acetylcholine receptors in dorsal root ganglion neurons include the α6β4* subtype.

    PubMed

    Hone, Arik J; Meyer, Erin L; McIntyre, Melissa; McIntosh, J Michael

    2012-02-01

    The α6-containing nicotinic acetylcholine receptors (nAChRs) have recently been implicated in diseases of the central nervous system (CNS), including Parkinson's disease and substance abuse. In contrast, little is known about the role of α6* nAChRs in the peripheral nervous system (where the asterisk denotes the possible presence of additional subunits). Dorsal root ganglia (DRG) neurons are known to express nAChRs with a pharmacology consistent with an α7, α3β4*, and α4β2* composition. Here we present evidence that DRG neurons also express α6* nAChRs. We used RT-PCR to show the presence of α6 subunit transcripts and patch-clamp electrophysiology together with subtype-selective α-conotoxins to pharmacologically characterize the nAChRs in rat DRG neurons. α-Conotoxin BuIA (500 nM) blocked acetylcholine-gated currents (I(ACh)) by 90.3 ± 3.0%; the recovery from blockade was very slow, indicating a predominance of α(x)β4* nAChRs. Perfusion with either 300 nM BuIA[T5A;P6O] or 200 nM MII[E11A], α-conotoxins that target the α6β4* subtype, blocked I(ACh) by 49.3 ± 5 and 46.7 ± 8%, respectively. In these neurons, I(ACh) was relatively insensitive to 200 nM ArIB[V11L;V16D] (9.4±2.0% blockade) or 500 nM PnIA (23.0±4% blockade), α-conotoxins that target α7 and α3β2*/α6β2* nAChRs, respectively. We conclude that α6β4* nAChRs are among the subtypes expressed by DRG, and to our knowledge, this is the first demonstration of α6β4* in neurons outside the CNS.

  9. Neuropathic Pain Post Spinal Cord Injury Part 2: Systematic Review of Dorsal Root Entry Zone Procedure

    PubMed Central

    2013-01-01

    Background: Pharmacotherapy may not sufficiently reduce neuropathic pain in many individuals post spinal cord injury (SCI). The use of alternative therapies such as surgery may be effective in reducing neuropathic pain in these individuals. However, because of the invasive nature of surgery, it is important to examine the evidence for use of this treatment. Objective: The purpose of this study was to conduct a systematic review of published literature on the surgical treatment of neuropathic pain after SCI. Methods: MEDLINE, CINAHL, EMBASE, and PsycINFO databases were searched for articles in which surgical treatment of pain after SCI was examined. Articles were restricted to the English language. Article selection was conducted by 2 independent reviewers with the following inclusion criteria: the subjects participated in a surgical intervention for neuropathic pain; at least 50% of the subjects had an SCI; at least 3 subjects had an SCI; and a definable intervention involving the dorsal root entry zone (DREZ) procedure was used to reduce pain. Data extracted included study design, study type, subject demographics, inclusion and exclusion criteria, sample size, outcome measures, and study results. Randomized controlled trials (RCTs) were assessed for quality using the Physiotherapy Evidence Database (PEDro) assessment scale. Levels of evidence were assigned to each intervention using a modified Sackett scale. Results: Eleven studies met the inclusion criteria. One study provided level 2 evidence, and the rest provided level 4 evidence. The DREZ procedure was shown to be more effective for segmental pain than for diffuse pain after SCI. Further, individuals with conus medullaris level injury were found to have a higher level of neuropathic pain relief than those with cervical, thoracic, or cauda equina injury. Conclusions: The studies demonstrated that the DREZ procedure may be effective in reducing segmental pain. Hence, DREZ may be important in treatment of

  10. TRPA1 Channels Modify TRPV1-Mediated Current Responses in Dorsal Root Ganglion Neurons.

    PubMed

    Masuoka, Takayoshi; Kudo, Makiko; Yamashita, Yuka; Yoshida, Junko; Imaizumi, Noriko; Muramatsu, Ikunobu; Nishio, Matomo; Ishibashi, Takaharu

    2017-01-01

    The transient receptor potential vanilloid 1 (TRPV1) channel is highly expressed in a subset of sensory neurons in the dorsal root ganglia (DRG) and trigeminal ganglia of experimental animals, responsible for nociception. Many researches have revealed that some TRPV1-positive neurons co-express the transient receptor potential ankyrin 1 (TRPA1) channel whose activities are closely modulated by TRPV1 channel. However, it is less investigated whether the activities of TRPV1 channel are modulated by the presence of TRPA1 channel in primary sensory neurons. This study clarified the difference in electrophysiological responses induced by TRPV1 channel activation between TRPA1-positive and TRPA1-negative DRG. TRPV1 and TRPA1 channel activations were evoked by capsaicin (1 μM), a TRPV1 agonist, and allyl isothiocyanate (AITC; 500 μM), a TRPA1 agonist, respectively. Capsaicin perfusion for 15 s caused a large inward current without a desensitization phase at a membrane potential of -70 mV in AITC-insensitive DRG (current density; 29.6 ± 5.6 pA/pF, time constant of decay; 12.8 ± 1.8 s). The capsaicin-induced currents in AITC-sensitive DRG had a small current density (12.7 ± 2.9 pA/pF) with a large time constant of decay (24.3 ± 5.4 s). In calcium imaging with Fura-2, the peak response by capsaicin was small and duration reaching the peak response was long in AITC-sensitive neurons. These electrophysiological differences were completely eliminated by HC-030031, a TRPA1 antagonist, in an extracellular solution or 10 mM EGTA, a Ca(2+) chelator, in an internal solution. Capsaicin perfusion for 120 s desensitized the inward currents after a transient peak. The decay during capsaicin perfusion was notably slow in AITC-sensitive DRG; ratio of capsaicin-induced current 60 s after the treatment per the peak current in AITC-sensitive neurons (78 ± 9%) was larger than that in AITC-insensitive neurons (48 ± 5%). The capsaicin-induced current in the desensitization phase was

  11. Intracellular chloride regulation in amphibian dorsal root ganglion neurones studied with ion-selective microelectrodes.

    PubMed Central

    Alvarez-Leefmans, F J; Gamiño, S M; Giraldez, F; Noguerón, I

    1988-01-01

    1. Intracellular Cl- activity (aiCl) and membrane potential (Em) were measured in frog dorsal root ganglion neurones (DRG neurones) using double-barrelled Cl- -selective microelectrodes. In standard Ringer solution buffered with HEPES (5 mM), equilibrated with air or 100% O2, the resting membrane potential was -57.7 +/- 1.0 mV and aiCl was 23.6 +/- 1.0 mM (n = 53). The value of aiCl was 2.6 times the activity expected for an equilibrium distribution and the difference between Em and ECl was 25 mV. 2. Removal of external Cl- led to a reversible fall in aiCl. Initial rates of decay and recovery of aiCl were 4.1 and 3.3 mM min-1, respectively. During the recovery of aiCl following return to standard Ringer solution, most of the movement of Cl- occurred against the driving force for a passive distribution. Changes in aiCl were not associated with changes in Em. Chloride fluxes estimated from initial rates of change in aiCl when external Cl- was removed were too high to be accounted for by electrodiffusion. 3. The intracellular accumulation of Cl- was dependent on the extracellular Cl- activity (aoCl). The relationship between aiCl and aoCl had a sigmoidal shape with a half-maximal activation of about 50 mM-external Cl-. 4. The steady-state aiCl depended on the simultaneous presence of extracellular Na+ and K+. Similarly, the active reaccumulation of Cl- after intracellular Cl- depletion was abolished in the absence of either Na+ or K+ in the bathing solution. 5. The reaccumulation of Cl- was inhibited by furosemide (0.5-1 x 10(-3) M) or bumetanide (10(-5) M). The decrease in aiCl observed in Cl- -free solutions was also inhibited by bumetanide. 6. Cell volume changes were calculated from the observed changes in aiCl. Cells were estimated to shrink in Cl- -free solutions to about 75% their initial volume, at an initial rate of 6% min-1. 7. The present results provide direct evidence for the active accumulation of Cl- in DRG neurones. The mechanism of Cl- transport is

  12. Role of neurotrophin signalling in the differentiation of neurons from dorsal root ganglia and sympathetic ganglia.

    PubMed

    Ernsberger, Uwe

    2009-06-01

    Manipulation of neurotrophin (NT) signalling by administration or depletion of NTs, by transgenic overexpression or by deletion of genes coding for NTs and their receptors has demonstrated the importance of NT signalling for the survival and differentiation of neurons in sympathetic and dorsal root ganglia (DRG). Combination with mutation of the proapoptotic Bax gene allows the separation of survival and differentiation effects. These studies together with cell culture analysis suggest that NT signalling directly regulates the differentiation of neuron subpopulations and their integration into neural networks. The high-affinity NT receptors trkA, trkB and trkC are restricted to subpopulations of mature neurons, whereas their expression at early developmental stages largely overlaps. trkC is expressed throughout sympathetic ganglia and DRG early after ganglion formation but becomes restricted to small neuron subpopulations during embryogenesis when trkA is turned on. The temporal relationship between trkA and trkC expression is conserved between sympathetic ganglia and DRG. In DRG, NGF signalling is required not only for survival, but also for the differentiation of nociceptors. Expression of neuropeptides calcitonin gene-related peptide and substance P, which specify peptidergic nociceptors, depends on nerve growth factor (NGF) signalling. ret expression indicative of non-peptidergic nociceptors is also promoted by the NGF-signalling pathway. Regulation of TRP channels by NGF signalling might specify the temperature sensitivity of afferent neurons embryonically. The manipulation of NGF levels "tunes" heat sensitivity in nociceptors at postnatal and adult stages. Brain-derived neurotrophic factor signalling is required for subpopulations of DRG neurons that are not fully characterized; it affects mechanical sensitivity in slowly adapting, low-threshold mechanoreceptors and might involve the regulation of DEG/ENaC ion channels. NT3 signalling is required for the

  13. Stem Cell-Derived Immature Human Dorsal Root Ganglia Neurons to Identify Peripheral Neurotoxicants

    PubMed Central

    Klima, Stefanie; Karreman, Christiaan; Grinberg, Marianna; Meisig, Johannes; Henry, Margit; Rotshteyn, Tamara; Rahnenführer, Jörg; Blüthgen, Nils; Sachinidis, Agapios; Waldmann, Tanja; Leist, Marcel

    2016-01-01

    Safety sciences and the identification of chemical hazards have been seen as one of the most immediate practical applications of human pluripotent stem cell technology. Protocols for the generation of many desirable human cell types have been developed, but optimization of neuronal models for toxicological use has been astonishingly slow, and the wide, clinically important field of peripheral neurotoxicity is still largely unexplored. A two-step protocol to generate large lots of identical peripheral human neuronal precursors was characterized and adapted to the measurement of peripheral neurotoxicity. High content imaging allowed an unbiased assessment of cell morphology and viability. The computational quantification of neurite growth as a functional parameter highly sensitive to disturbances by toxicants was used as an endpoint reflecting specific neurotoxicity. The differentiation of cells toward dorsal root ganglia neurons was tracked in relation to a large background data set based on gene expression microarrays. On this basis, a peripheral neurotoxicity (PeriTox) test was developed as a first toxicological assay that harnesses the potential of human pluripotent stem cells to generate cell types/tissues that are not otherwise available for the prediction of human systemic organ toxicity. Testing of more than 30 chemicals showed that human neurotoxicants and neurite growth enhancers were correctly identified. Various classes of chemotherapeutic agents causing human peripheral neuropathies were identified, and they were missed when tested on human central neurons. The PeriTox test we established shows the potential of human stem cells for clinically relevant safety testing of drugs in use and of new emerging candidates. Significance The generation of human cells from pluripotent stem cells has aroused great hopes in biomedical research and safety sciences. Neurotoxicity testing is a particularly important application for stem cell-derived somatic cells, as

  14. Upregulation of high affinity GABAA receptors in cultured rat dorsal root ganglion neurons

    PubMed Central

    Lee, Kwan Yeop; Charbonnet, Marcel; Gold, Michael S.

    2012-01-01

    Despite evidence that high-affinity GABAA receptor subunit mRNA and protein are present in dorsal root ganglia (DRG), low affinity currents dominate those detected in acutely dissociated DRG neurons in vitro. This observation raises the possibility that high affinity receptors are normally trafficked out of the DRG toward central and peripheral terminals. We therefore hypothesized that with time in culture, there would be an increase in high-affinity GABAA currents in DRG neurons. To test this hypothesis, we studied dissociated DRG neurons 2 hrs (acute) and 24 hrs (cultured) after plating with whole cell patch clamp techniques, western blot and qRT-PCR analysis. GABAA current density increases dramatically with time in culture in association with the emergence of two persistent currents with EC50’s of 0.25 ± 0.01 μM and 3.2 ± 0.02 μM for GABA activation. In a subpopulation of neurons, there was also an increase in the potency of GABA activation of the transient current from an EC50 of 78.16 ± 10.1 μM to 9.56 ± 1.3 μM with time in culture. A fraction of the high affinity current was potentiated by δ-subunit agonist 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridine-3-ol (THIP). δ-subunit immunoreactivity was largely restricted to the cytosolic fraction in acute but the membrane fraction in cultured DRG neurons with no detectable change in δ-subunit mRNA. However, the emergence of a high affinity current blocked by THIP and insensitive to bicuculline was detected in a subpopulation of cultured neurons as well in association with an increase in ρ2 and 3-subunit mRNA in cultured DRG neurons. Our results suggest that high-affinity δ-subunit containing GABAA receptors are normally trafficked out of the DRG where they are targeted to peripheral and central processes. They also highlight that the interpretation of data obtained from cultured DRG neurons should be made with caution. PMID:22366297

  15. [Effect of spontaneous firing of injured dorsal root ganglion neuron on excitability of wide dynamic range neuron in rat spinal dorsal horn].

    PubMed

    Song, Ying; Zhang, Yong-Mei; Xu, Jie; Wu, Jing-Ru; Qin, Xia; Hua, Rong

    2013-10-25

    The aim of the paper is to study the effect of spontaneous firing of injured dorsal root ganglion (DRG) neuron in chronic compression of DRG (CCD) model on excitability of wide dynamic range (WDR) neuron in rat spinal dorsal horn. In vivo intracellular recording was done in DRG neurons and in vivo extracellular recording was done in spinal WDR neurons. After CCD, incidence of spontaneous discharge and firing frequency enhanced to 59.46% and (4.30 ± 0.69) Hz respectively from 22.81% and (0.60 ± 0.08) Hz in normal control group (P < 0.05). Local administration of 50 nmol/L tetrodotoxin (TTX) on DRG neuron in CCD rats decreased the spontaneous activities of WDR neurons from (191.97 ± 45.20)/min to (92.50 ± 30.32)/min (P < 0.05). On the other side, local administration of 100 mmol/L KCl on DRG neuron evoked spontaneous firing in a reversible way (n = 5) in silent WDR neurons of normal rats. There was 36.36% (12/33) WDR neuron showing after-discharge in response to innocuous mechanical stimuli on cutaneous receptive field in CCD rats, while after-discharge was not seen in control rats. Local administration of TTX on DRG with a concentration of 50 nmol/L attenuated innocuous electric stimuli-evoked after-discharge of WDR neurons in CCD rats in a reversible manner, and the frequency was decreased from (263 ± 56.5) Hz to (117 ± 30) Hz (P < 0.05). The study suggests that the excitability of WDR neurons is influenced by spontaneous firings of DRG neurons after CCD.

  16. [EFFECT OF PEPTIDE SEMAX ON SYNAPTIC ACTIVITY AND SHORT-TERM PLASTICITY OF GLUTAMATERGIC SYNAPSES OF CO-CULTURED DORSAL ROOT GANGLION AND DORSAL HORN NEURONS].

    PubMed

    Shypshyna, M S; Veselovsky, N S; Myasoedov, N F; Shram, S I; Fedulova, S A

    2015-01-01

    The influence of long-term culturing (12 days in vitro) of dorsal root ganglion (DRG) and dorsal horn (DH) neurons with peptide Semax on the level of synaptic activity at co-cultures, as well as short-term plasticity in sensory synapses were studied. It has been shown that neuronal culturing with peptide at concentrations of 10 and 100 µM led to increasing the frequency of spontaneous glutamatergic postsynaptic currents in DH neurons to 71.7 ± 1.8% and 93.9 ± 3.1% (n = 6; P < 0.001); Semax has a not significant effect on the amplitude and frequency of miniature glutamatergic currents, but causes an increase of the amplitudes of spontaneous postsynaptic currents, as well as elevates the quantum content. The data show the increase of multivesicular glutamate release efficiency in neural networks of co-cultures following incubation with the peptide. Also Semax (10 and 100 µM) induces changes of the basic parameters of short-term plasticity in sensory synapses: (1) increasing the paired-pulse ratio from 0.53 ± 0.028 (n = 8) to 0.91 ± 0.072 (n = 6, P < 0.01) and 0.95 ± 0.026 (n = 7; P < 0.001); (2) reducing the ratio of the coefficients of variation (CV2/ CV1) from 1.49 ± 0.11 (n = 8) to 1.02 ± 0.09 (n = 6; P < 0.05) and 1.11 ± 0.13 (n = 7; P < 0.0) respectively. The results indicate a stimulating effect of Semax on the activity of glutamatergic synapses in neural networks of co-cultures, as well as the ability of the peptide to effectively modulate the short-term plasticity in sensory synapses.

  17. Effects of combined electrical stimulation of the dorsal column and dorsal roots on wide-dynamic range neuronal activity in nerve-injured rats

    PubMed Central

    Yang, Fei; Zhang, Tong; Tiwari, Vinod; Shu, Bin; Zhang, Chen; Wang, Yun; Vera-Portocarrero, Louis P.; Raja, Srinivasa N.; Guan, Yun

    2015-01-01

    Objectives Electrical stimulation at the dorsal column (DC) and dorsal root (DR) may inhibit spinal wide-dynamic-range (WDR) neuronal activity in nerve-injured rats. The objective of this study was to determine if applying electrical conditioning stimulation (CS) at both sites provides additive or synergistic benefits. Materials and Methods By conducting in vivo extracellular recordings of WDR neurons in rats that had undergone L5 spinal nerve ligation, we tested whether combining 50 Hz CS at the two sites in either a concurrent (2.5 minutes) or alternate (5 minutes) pattern inhibits WDR neuronal activity better than CS at DC alone (5 minutes). The intensities of CS were determined by recording antidromic compound action potentials to graded stimulation at the DC and DR. We measured the current thresholds that resulted in the first detectable Aα/β waveform (Ab0) and the peak Aα/β waveform (Ab1) to select CS intensity at each site. The same number of electrical pulses and amount of current were delivered in different patterns to allow comparison. Results At a moderate intensity of 50%(Ab0+Ab1), different patterns of CS all attenuated the C-component of WDR neurons in response to graded intracutaneous electrical stimuli (0.1-10 mA, 2 ms), and inhibited windup in response to repetitive noxious stimuli (0.5 Hz). However, the inhibitory effects did not differ significantly between different patterns. At the lower intensity (Ab0), no CS inhibited WDR neurons. Conclusions These findings suggest that combined stimulation of DC and DR may not be superior to DC stimulation alone for inhibition of WDR neurons. PMID:26307526

  18. Effects of Combined Electrical Stimulation of the Dorsal Column and Dorsal Roots on Wide-Dynamic-Range Neuronal Activity in Nerve-Injured Rats.

    PubMed

    Yang, Fei; Zhang, Tong; Tiwari, Vinod; Shu, Bin; Zhang, Chen; Wang, Yun; Vera-Portocarrero, Louis P; Raja, Srinivasa N; Guan, Yun

    2015-10-01

    Electrical stimulation at the dorsal column (DC) and dorsal root (DR) may inhibit spinal wide-dynamic-range (WDR) neuronal activity in nerve-injured rats. The objective of this study was to determine if applying electrical conditioning stimulation (CS) at both sites provides additive or synergistic benefits. By conducting in vivo extracellular recordings of WDR neurons in rats that had undergone L5 spinal nerve ligation, we tested whether combining 50 Hz CS at the two sites in either a concurrent (2.5 min) or alternate (5 min) pattern inhibits WDR neuronal activity better than CS at DC alone (5 min). The intensities of CS were determined by recording antidromic compound action potentials to graded stimulation at the DC and DR. We measured the current thresholds that resulted in the first detectable Aα/β waveform (Ab0) and the peak Aα/β waveform (Ab1) to select CS intensity at each site. The same number of electrical pulses and amount of current were delivered in different patterns to allow comparison. At a moderate intensity of 50% (Ab0 + Ab1), different patterns of CS all attenuated the C-component of WDR neurons in response to graded intracutaneous electrical stimuli (0.1-10 mA, 2 msec) and inhibited windup in response to repetitive noxious stimuli (0.5 Hz). However, the inhibitory effects did not differ significantly between different patterns. At the lower intensity (Ab0), no CS inhibited WDR neurons. These findings suggest that combined stimulation of DC and DR may not be superior to DC stimulation alone for inhibition of WDR neurons. © 2015 International Neuromodulation Society.

  19. Follow-up 26 years after dorsal root entry zone thermocoagulation for brachial plexus avulsion and phantom limb pain.

    PubMed

    Tomycz, Nestor D; Moossy, John J

    2011-01-01

    Brachial plexus avulsion and limb amputation are often associated with intractable chronic pain. Dorsal root entry zone (DREZ) thermocoagulation is an effective surgical treatment for upper-extremity deafferentation pain. The authors describe the clinical follow-up and imaging in a patient who underwent DREZ thermocoagulation 26 years ago for postamputation phantom limb syndrome with associated brachial plexus avulsion. This patient continues to have successful pain control without phantom limb sensation and has never experienced a recurrence of his left upper-extremity pain syndrome. This report lends credibility to the notion that, among ablative neurosurgical pain operations, DREZ thermocoagulation may provide the greatest durability of pain control.

  20. Leukemia inhibitory factor induces sympathetic sprouting in intact dorsal root ganglia in the adult rat in vivo

    PubMed Central

    Thompson, Stephen W N; Majithia, Anooj A

    1998-01-01

    The role of the cytokine leukemia inhibitory factor (LIF) in axotomy-induced sprouting of postganglionic sympathetic fibres into the dorsal root ganglia was examined in the adult rat.Immunocytochemistry was used to study the distribution and density of tyrosine hydroxylase-immunoreactive (TH-IR) fibres within the lumbar dorsal root ganglia and lumbar spinal nerves 14 days following continuous intrathecal infusion of LIF (0.33 mg ml−1), or 14 days following unilateral peripheral nerve axotomy.In LIF-treated animals, numerous pericellular TH-IR basket-like structures were observed surrounding sensory neurones, which were absent from controls.The number of TH-IR fibres within the L3, L4 and L5 spinal nerves was significantly higher in LIF-treated animals than in control or saline-treated animals (P < 0.01, Student's t test).Unilateral ligation of the L4 spinal nerve or unilateral sciatic nerve ligation was also associated with the formation of TH-IR baskets around sensory neurones and a significant increase in the number of TH-IR fibres within the lumbar spinal nerves (P < 0.01, Student's t test).The percentage of neurones surrounded by TH-IR baskets within the L3 and L4 dorsal root ganglia following sciatic axotomy was significantly reduced in animals treated continuously for 2 weeks with a monoclonal antibody against the LIF receptor motif, gp130 (0.833 mg ml−1) (P < 0.05, Mann-Whitney U test). Antibody treatment did not reduce the axotomy-induced increase in TH-IR fibres within lumbar spinal nerves.These results demonstrate that exogenous application of the axotomy-associated cytokine LIF is associated with sprouting of uninjured postganglionic sympathetic neurones around sensory neurones within the dorsal root ganglion. It is likely that increased LIF expression following peripheral axotomy plays an important role in the novel sympathetic sprouting observed within sensory ganglia following peripheral nerve injury. PMID:9503339

  1. The roots of modern justice: cognitive and neural foundations of social norms and their enforcement.

    PubMed

    Buckholtz, Joshua W; Marois, René

    2012-04-15

    Among animals, Homo sapiens is unique in its capacity for widespread cooperation and prosocial behavior among large and genetically heterogeneous groups of individuals. This ultra-sociality figures largely in our success as a species. It is also an enduring evolutionary mystery. There is considerable support for the hypothesis that this facility is a function of our ability to establish, and enforce through sanctions, social norms. Third-party punishment of norm violations ("I punish you because you harmed him") seems especially crucial for the evolutionary stability of cooperation and is the cornerstone of modern systems of criminal justice. In this commentary, we outline some potential cognitive and neural processes that may underlie the ability to learn norms, to follow norms and to enforce norms through third-party punishment. We propose that such processes depend on several domain-general cognitive functions that have been repurposed, through evolution's thrift, to perform these roles.

  2. Effects of norepinephrine on galanin expression in dorsal root ganglion neurons in vitro

    PubMed Central

    Yang, Xiangdong; Liu, Zhen; Li, Zhenzhong

    2009-01-01

    Background: Norepinephrine (NE) is a key neurotransmitter that functionally activates adrenoreceptors expressed in sympathetic neurons. Functional α1-adrenoreceptors are also expressed in dorsal root ganglion (DRG) primary sensory neurons and regulate neurogenic inflammation and nociceptive responses. Galanin is involved in inflammation and nociception. It has been suggested that galanin receptor (GalR) 1 and GalR3 activation induces analgesia at the level of the spinal cord, while activation of GalR2 has a pronociceptive role in the periphery. Whether activation or inhibition of α-adrenoreceptors influences galanin expression remains unknown. Objective: The aim of the present study was to investigate whether the α-adrenoreceptor agonist NE, the α1-adrenoreceptor antagonist prazosin, and the α2-adrenoreceptor antagonist yohimbine affect galanin expression in primary cultured DRG neurons. Methods: DRG was dissected from 240 embryonic 15-day-old Wistar rats, cultured as dissociated cells for 2 days, and then exposed to NE (10-4 mol/L) for another 4 days. In the NE + prazosin group and the NE + yohimbine group, DRG neurons were pretreated with prazosin (10-6 mol/L) and yohimbine (10-5 mol/L), respectively, 10 minutes prior to the NE challenge. The neurons cultured continuously in media served as the controls. All of the cultured samples were processed to detect galanin mRNA and galanin peptide expression by reverse transcriptase-polymerase chain reaction and Western blot, respectively. Five samples were tested for each procedure. Results: Forty samples were prepared for this study and included in the analysis. After 4 days of incubation, mean (SD) galanin mRNA/β-actin mRNA concentration ratio was significantly increased with NE compared with controls (0.3349 [0.0413] vs 0.2411 [0.0519]; P < 0.05). Pretreatment with prazosin seemed to block the effects of NE (0.2522 [0.0496]; P < 0.05 vs NE), while yohimbine did not appear to significantly alter the effects of NE

  3. Sox10 contributes to the balance of fate choice in dorsal root ganglion progenitors

    PubMed Central

    Madelaine, Romain; Busolin, Giorgia; Nikaido, Masataka; Colanesi, Sarah; Camargo-Sosa, Karen; Toppo, Stefano; Blader, Patrick; Tiso, Natascia; Kelsh, Robert N.

    2017-01-01

    The development of functional peripheral ganglia requires a balance of specification of both neuronal and glial components. In the developing dorsal root ganglia (DRGs), these components form from partially-restricted bipotent neuroglial precursors derived from the neural crest. Work in mouse and chick has identified several factors, including Delta/Notch signaling, required for specification of a balance of these components. We have previously shown in zebrafish that the Sry-related HMG domain transcription factor, Sox10, plays an unexpected, but crucial, role in sensory neuron fate specification in vivo. In the same study we described a novel Sox10 mutant allele, sox10baz1, in which sensory neuron numbers are elevated above those of wild-types. Here we investigate the origin of this neurogenic phenotype. We demonstrate that the supernumerary neurons are sensory neurons, and that enteric and sympathetic neurons are almost absent just as in classical sox10 null alleles; peripheral glial development is also severely abrogated in a manner similar to other sox10 mutant alleles. Examination of proliferation and apoptosis in the developing DRG reveals very low levels of both processes in wild-type and sox10baz1, excluding changes in the balance of these as an explanation for the overproduction of sensory neurons. Using chemical inhibition of Delta-Notch-Notch signaling we demonstrate that in embryonic zebrafish, as in mouse and chick, lateral inhibition during the phase of trunk DRG development is required to achieve a balance between glial and neuronal numbers. Importantly, however, we show that this mechanism is insufficient to explain quantitative aspects of the baz1 phenotype. The Sox10(baz1) protein shows a single amino acid substitution in the DNA binding HMG domain; structural analysis indicates that this change is likely to result in reduced flexibility in the HMG domain, consistent with sequence-specific modification of Sox10 binding to DNA. Unlike other Sox10

  4. Orexin A and orexin receptor 1 axonal traffic in dorsal roots at the CNS/PNS interface.

    PubMed

    Colas, Damien; Manca, Annalisa; Delcroix, Jean-Dominique; Mourrain, Philippe

    2014-01-01

    Hypothalamic orexin/hypocretin neurons send long axonal projections through the dorsal spinal cord in lamina I-II of the dorsal horn (DH) at the interface with the peripheral nervous system (PNS). We show that in the DH OXA fibers colocalize with substance P (SP) positive afferents of dorsal root ganglia (DRG) neurons known to mediate sensory processing. Further, OR1 is expressed in p75(NTR) and SP positive DRG neurons, suggesting a potential signaling pathway between orexin and DRG neurons. Interestingly, DRG sensory neurons have a distinctive bifurcating axon where one branch innervates the periphery and the other one the spinal cord (pseudo-unipolar neurons), allowing for potential functional coupling of distinct targets. We observe that OR1 is transported selectively from DRG toward the spinal cord, while OXA is accumulated retrogradely toward the DRG. We hence report a rare situation of asymmetrical neuropeptide receptor distribution between axons projected by a single neuron. These molecular and cellular data are consistent with the role of OXA/OR1 in sensory processing, including DRG neuronal modulation, and support the potential existence of an OX/HCRT circuit between CNS and PNS.

  5. Glial cell responses, complement, and clusterin in the central nervous system following dorsal root transection.

    PubMed

    Liu, L; Persson, J K; Svensson, M; Aldskogius, H

    1998-07-01

    We have examined the glial cell response, the possible expression of compounds associated with the complement cascade, including the putative complement inhibitor clusterin, and their cellular association during Wallerian degeneration in the central nervous system. Examination of the proliferation pattern revealed an overall greater mitotic activity after rhizotomy, an exclusive involvement of microglia in this proliferation after peripheral nerve injury, but, in addition, a small fraction of proliferating astrocytes after rhizotomy. Immunostaining with the phagocytic cell marker ED1 gradually became very prominent after rhizotomy, possibly reflecting a response to the extensive nerve fiber disintegration. Lumbar dorsal rhizotomy did not induce endogenous immunoglobulin G (IgG) deposition or complement expression in the spinal cord dorsal horn, dorsal funiculus, or gracile nucleus. This is in marked contrast to the situation after peripheral nerve injury, which appears to activate the entire complement cascade in the vicinity of the central sensory processes. Clusterin, a multifunctional protein with complement inhibitory effects, was markedly upregulated in the dorsal funiculus in astrocytes. In addition, there was an intense induction of clusterin expression in the degenerating white matter in oligodendrocytes, possibly reflecting a degeneration process in these cells. The findings suggest that 1) complement expression by microglial cells is intimately associated with IgG deposition; 2) axotomized neuronal perikarya, but not degenerating central fibers, undergo changes which induce such deposition; and 3) clusterin is not related to complement expression following neuronal injury but participates in regulating the state of oligodendrocytes during Wallerian degeneration.

  6. [Upregulation of P2X3 receptors in dorsal root ganglion of TRPV1 knockout female mice].

    PubMed

    Fang, Xiao; Shi, Xiao-Han; Huang, Li-Bin; Rong, Wei-Fang; Ma, Bei

    2014-08-25

    The study was aimed to investigate the changes in mechanical pain threshold in the condition of chronic inflammatory pain after transient receptor potential vanilloid 1 (TRPV1) gene was knockout. Hind-paw intraplantar injection of complete freund's adjuvant (CFA, 20 μL) produced peripheral inflammation in wild-type and TRPV1 knockout female mice. The mechanical pain thresholds were measured during the 8 days after injection and pre-injection by using Von-Frey hair. Nine days after injection, mice were killed and the differences of expression of c-Fos and P2X3 receptor in the dorsal root ganglia (DRG) and spinal cord dorsal horn were examined by Western blotting between the two groups. Compared with that in wild-type mice, the mechanical pain threshold was increased significantly in TRPV1 knockout mice (P < 0.05); 3 days after CFA injection, the baseline mechanical pain threshold in the TRPV1 knockout mice group was significantly higher than that in the wild-type mice group (P < 0.05); The result of Western blotting showed that the expression of c-Fos protein both in DRG and spinal cord dorsal horn of TRPV1 knockout mice group was decreased significantly compared with that in wild-type mice group (P < 0.01, P < 0.05), while the expression of P2X3 receptor in DRG of TRPV1 knockout mice group was increased significantly compared with that in wild-type mice group (P < 0.05). Our findings indicate that TRPV1 may influence the peripheral mechanical pain threshold by mediating the expression of c-Fos protein both in DRG and spinal cord dorsal horn and changing the expression of P2X3 receptor in DRG.

  7. Capsaicin-stimulated release of substance P from cultured dorsal root ganglion neurons: involvement of two distinct mechanisms.

    PubMed

    Purkiss, J; Welch, M; Doward, S; Foster, K

    2000-06-01

    Capsaicin, the pungent component of "hot" chili peppers, selectively activates a distinct population of primary sensory neurons responsive to noxious stimuli. Many of these fibres express neuropeptides including the tachykinin, substance P. Using cultured dorsal root ganglion neurons, we found that capsaicin (10 microM) stimulated a 2-fold increase in release of substance P in the absence of extracellular Ca(2+). Elevated potassium (75 mM) was unable to induce release under these conditions. The introduction of Ca(2+) enhanced capsaicin-induced release and brought about a robust response to potassium. Preincubation of cells with botulinum neurotoxin A (100 nM) completely blocked potassium-induced release but the capsaicin response, in the absence of Ca(2+), was unaffected. However, toxin treatment dramatically reduced capsaicin-stimulated release in the presence of Ca(2+). It is concluded that capsaicin induces release of substance P from dorsal root ganglion neurons via two mechanisms, one requiring extracellular Ca(2+) and the intact synaptosomal-associated protein 25 kDa (SNAP-25), and the other independent of extracellular Ca(2+) and not involving SNAP-25.

  8. Comparison of calcium imaging in dorsal root ganglion neurons by using laser scanning confocal and two-photon microscopy

    NASA Astrophysics Data System (ADS)

    Huang, Yimei; Yang, Hongqin; Chen, Jiangxu; Shen, Xiuqiu; Zheng, Liqin; Wang, Yuhua; Xie, Shusen

    2012-03-01

    As one of the most important second messengers, calcium in nerve cells plays a critical role in neuronal processes, including excitability, neurotransmitter release, synaptic plasticity. Modulation of the calcium concentration is an important means of regulating diverse neuronal functions. To evaluate the role of calcium, quantitative measurement of cytosolic free calcium concentrations is necessary. There are several optical techniques that are available for measurement of calcium in live cells. Laser scanning confocal microscopy and two-photon microscopy are two prevalent techniques for their advantage in spatial resolution. In this paper, calcium in dorsal root ganglion neurons was imaged by laser scanning confocal microscopy and two-photon microscopy with Fluo-3, a calcium specific fluorescence probe. Both of spatial resolution and photobleaching, two common limitations of optical image modality, were compared between laser scanning confocal microscopy and two-photon microscopy, respectively. Three dimension images showed that laser scanning confocal microscopy and two-photon microscopy had not only similar lateral resolution but also parallel vertical resolution. However, Laser scanning confocal microscopy had an advantage over the two-photon microcopy in photobleaching. These results indicated that laser scanning confocal microscopy was more suitable than two-photon microscopy to be applied in imaging calcium in dorsal root ganglion neurons with Fluo-3.

  9. S3 Dorsal Root Ganglion/Nerve Root Stimulation for Refractory Postsurgical Perineal Pain: Technical Aspects of Anchorless Sacral Transforaminal Lead Placement

    PubMed Central

    Zuidema, X.; Breel, J.; Wille, F.

    2016-01-01

    Chronic perineal pain limits patients in physical and sexual activities, leading to social and psychological distress. In most cases, this pain develops after surgery in the urogenital area or as a consequence of trauma. Neuromodulation is one of the options in chronic postsurgical perineal pain treatment. We present a case of refractory perineal pain after right sided surgical resection of a Bartholin's cyst which was treated with third sacral nerve root/dorsal root ganglion stimulation using the transforaminal approach. We describe a new anchorless lead placement technique using a unique curved lead delivery sheath. We postulate that this new posterior foraminal technique of lead placement is simple, safe, and reversible and may lower the occurrence of lead related complications. PMID:27123351

  10. Extracorporeal shockwave application to the distal femur of rabbits diminishes the number of neurons immunoreactive for substance P in dorsal root ganglia L5.

    PubMed

    Hausdorf, Jörg; Lemmens, Marijke A M; Kaplan, Suleyman; Marangoz, Cafer; Milz, Stefan; Odaci, Ersan; Korr, Hubert; Schmitz, Christoph; Maier, Markus

    2008-05-01

    Application of extracorporeal shockwaves to the musculoskeletal system can induce long-term analgesia in the treatment of chronic painful diseases such as calcifying tendonitis of the shoulder, tennis elbow and chronic plantar fasciitis. However, the molecular and cellular mechanisms underlying this phenomenon are largely unknown. Recently it was shown that application of extracorporeal shockwaves to the distal femur of rabbits can lead to reduced concentration of substance P in the shockwaves' focal zone. In the present study we investigated the impact of extracorporeal shockwaves on the production of substance P within dorsal root ganglia in vivo. High-energy shockwaves were applied to the ventral side of the right distal femur of rabbits. After six weeks, the dorsal root ganglia L5 to L7 were investigated with high-precision design-based stereology. The application of extracorporeal shockwaves caused a statistically significant decrease in the mean number of neurons immunoreactive for substance P within the dorsal root ganglion L5 of the treated side compared with the untreated side, without affecting the total number of neurons within this dorsal root ganglion. No effect was observed in the dorsal root ganglia L6 and L7, respectively. These data might further contribute to our understanding of the molecular and cellular mechanisms in the induction of long-term analgesia by extracorporeal shockwave application to the musculoskeletal system.

  11. Impacts of anti-nerve growth factor antibody on pain-related behaviors and expressions of opioid receptor in spinal dorsal horn and dorsal root ganglia of rats with cancer-induced bone pain

    PubMed Central

    Ding, Yuanyuan; Wang, Zhibin; Ma, Jiaming; Hong, Tao; Zhu, Yongqiang; Li, Hongxi; Pan, Shinong

    2016-01-01

    Objective To investigate the impacts of anti-nerve growth factor antibody on pain-related behaviors and expressions of μ-opioid receptor in spinal dorsal horn and dorsal root ganglia of rats with cancer-induced bone pain. Methods The rats were randomly grouped and then injected with 10 μl of phosphate buffer saline or Walker256 tumor cells into the upper segment of left tibia. Thirteen days after the injection, the intrathecal catheterization was performed, followed by the injection of saline, anti-nerve growth factor, nerve growth factor, and naloxone twice a day. The pain ethological changes were measured at the set time points; the expression changes of μ-opioid receptor protein and mRNA in spinal dorsal horn and dorsal root ganglia were detected on the 18th day. Results After the tumor cells were injected into the tibia, hyperalgesia appeared and the expression of μ-opioid receptor protein and mRNA in spinal dorsal horn and dorsal root ganglia was increased, compared with the sham group; after intrathecally injected anti-nerve growth factor, the significant antinociceptive effects appeared, and the μ-opioid receptor expression was increased, compared with the cancer pain group; the μ-opioid receptor expressions in the other groups showed no statistical significance. The naloxone pretreatment could mostly inverse the antinociception effects of anti-nerve growth factor. Conclusions Anti-nerve growth factor could reduce hyperalgesia in the cancer-induced bone pain rats, and the antinociceptive effects were related with the upregulation of μ-opioid receptor. PMID:27118770

  12. Inhibition of tetrodotoxin-resistant sodium current in dorsal root ganglia neurons mediated by D1/D5 dopamine receptors

    PubMed Central

    2013-01-01

    Background Dopaminergic fibers originating from area A11 of the hypothalamus project to different levels of the spinal cord and represent the major source of dopamine. In addition, tyrosine hydroxylase, the rate-limiting enzyme for the synthesis of catecholamines, is expressed in 8-10% of dorsal root ganglia (DRG) neurons, suggesting that dopamine may be released in the dorsal root ganglia. Dopamine has been shown to modulate calcium current in DRG neurons, but the effects of dopamine on sodium current and on the firing properties of small DRG neurons are poorly understood. Results The effects of dopamine and dopamine receptor agonists were tested on the tetrodotoxin-resistant (TTX-R) sodium current recorded from acutely dissociated small (diameter ≤ 25 μm) DRG neurons. Dopamine (20 μM) and SKF 81297 (10 μM) caused inhibition of TTX-R sodium current in small DRG neurons by 23% and 37%, respectively. In contrast, quinpirole (20 μM) had no effects on the TTX-R sodium current. Inhibition by SKF 81297 of the TTX-R sodium current was not affected when the protein kinase A (PKA) activity was blocked with the PKA inhibitory peptide (6–22), but was greatly reduced when the protein kinase C (PKC) activity was blocked with the PKC inhibitory peptide (19–36), suggesting that activation of D1/D5 dopamine receptors is linked to PKC activity. Expression of D1and D5 dopamine receptors in small DRG neurons, but not D2 dopamine receptors, was confirmed by Western blotting and immunofluorescence analysis. In current clamp experiments, the number of action potentials elicited in small DRG neurons by current injection was reduced by ~ 30% by SKF 81297. Conclusions We conclude that activation of D1/D5 dopamine receptors inhibits TTX-R sodium current in unmyelinated nociceptive neurons and dampens their intrinsic excitability by reducing the number of action potentials in response to stimulus. Increasing or decreasing levels of dopamine in the dorsal root ganglia

  13. Sensitization of Primary Afferent Nociceptors Induced by Intradermal Capsaicin Involves the Peripheral Release of Calcitonin Gene-Related Peptide Driven by Dorsal Root Reflexes

    PubMed Central

    Li, Dingge; Ren, Yong; Xu, Xijin; Zou, Xiaoju; Fang, Li; Lin, Qing

    2008-01-01

    Neuropeptides released from axons of primary afferent nociceptive neurons are the key elements for the incidence of neurogenic inflammation and their release is associated with dorsal root reflexes (DRRs). However, whether the release is due to the triggering of DRRs and plays a role in inflammation-induced pain still remain to be determined. The present study assessed the role of calcitonin gene-related peptide (CGRP) in sensitization of primary afferent nociceptors induced by activation of transient receptor potential vanilloid-1 (TRPV1) following intradermal injection of capsaicin and determined if this release is due to activation of primary afferent neurons antidromically by triggering of DRRs. Under dorsal root intact conditions, primary afferent nociceptive fibers recorded in anesthetized rats could be sensitized by capsaicin injection, as shown by an increase in afferent responses and lowering of the response threshold to mechanical stimuli. After DRRs were removed by dorsal rhizotomy, the capsaicin-evoked sensitization was significantly reduced. In dorsal root intact rats, peripheral pretreatment with a CGRP receptor antagonist could dose-dependently reduce the capsaicin-induced sensitization. Peripheral post-treatment with CGRP could dose-dependently restore the capsaicin-induced sensitization under dorsal rhizotomized conditions. Capsaicin injection evoked increases in numbers of single and double labeled TRPV1 and CGRP neurons in ipsilateral dorsal root ganglia (DRG). After dorsal rhizotomy, these evoked expressions were significantly inhibited. Perspective These data indicate that the DRR-mediated neurogenic inflammation enhances sensitization of primary afferent nociceptors induced by capsaicin injection. The underlying mechanism involves antidromic activation of DRG neurons via up-regulation of TRPV1 receptors whereby CGRP is released peripherally. PMID:18701354

  14. CT-guided injection of a TRPV1 agonist around dorsal root ganglia decreases pain transmission in swine

    PubMed Central

    Brown, Jacob D.; Saeed, Maythem; Do, Loi; Braz, Joao; Basbaum, Allan I.; Iadarola, Michael J.; Wilson, David M.; Dillon, William P.

    2016-01-01

    One approach to analgesia is to block pain at the site of origin or along the peripheral pathway by selectively ablating pain-transmitting neurons or nerve terminals directly. The heat/capsaicin receptor (TRPV1) expressed by nociceptive neurons is a compelling target for selective interventional analgesia because it leaves somatosensory and proprioceptive neurons intact. Resiniferatoxin (RTX), like capsaicin, is a TRPV1 agonist but has greater potency. We combine RTX-mediated inactivation with the precision of computed tomography (CT)–guided delivery to ablate peripheral pain fibers in swine. Under CT guidance, RTX was delivered unilaterally around the lumbar dorsal root ganglia (DRG), and vehicle only was administered to the contralateral side. During a 4-week observation period, animals demonstrated delayed or absent withdrawal responses to infrared laser heat stimuli delivered to sensory dermatomes corresponding to DRG receiving RTX treatment. Motor function was unimpaired as assessed by disability scoring and gait analysis. In treated DRG, TRPV1 mRNA expression was reduced, as were nociceptive neuronal perikarya in ganglia and their nerve terminals in the ipsilateral dorsal horn. CT guidance to precisely deliver RTX to sites of peripheral pain transmission in swine may be an approach that could be tailored to block an array of clinical pain conditions in patients. PMID:26378245

  15. CT-guided injection of a TRPV1 agonist around dorsal root ganglia decreases pain transmission in swine.

    PubMed

    Brown, Jacob D; Saeed, Maythem; Do, Loi; Braz, Joao; Basbaum, Allan I; Iadarola, Michael J; Wilson, David M; Dillon, William P

    2015-09-16

    One approach to analgesia is to block pain at the site of origin or along the peripheral pathway by selectively ablating pain-transmitting neurons or nerve terminals directly. The heat/capsaicin receptor (TRPV1) expressed by nociceptive neurons is a compelling target for selective interventional analgesia because it leaves somatosensory and proprioceptive neurons intact. Resiniferatoxin (RTX), like capsaicin, is a TRPV1 agonist but has greater potency. We combine RTX-mediated inactivation with the precision of computed tomography (CT)-guided delivery to ablate peripheral pain fibers in swine. Under CT guidance, RTX was delivered unilaterally around the lumbar dorsal root ganglia (DRG), and vehicle only was administered to the contralateral side. During a 4-week observation period, animals demonstrated delayed or absent withdrawal responses to infrared laser heat stimuli delivered to sensory dermatomes corresponding to DRG receiving RTX treatment. Motor function was unimpaired as assessed by disability scoring and gait analysis. In treated DRG, TRPV1 mRNA expression was reduced, as were nociceptive neuronal perikarya in ganglia and their nerve terminals in the ipsilateral dorsal horn. CT guidance to precisely deliver RTX to sites of peripheral pain transmission in swine may be an approach that could be tailored to block an array of clinical pain conditions in patients. Copyright © 2015, American Association for the Advancement of Science.

  16. Modulating nitric oxide levels in dorsal root ganglion neurons of rat with low-level laser therapy

    NASA Astrophysics Data System (ADS)

    Zheng, Li-qin; Wang, Yu-hua; He, Yi-peng; Zhou, Jie; Yang, Hong-qin; Zhang, Yan-ding; Xie, Shu-sen

    2015-05-01

    Nitric oxide (NO) and nitric oxide synthase (NOS) have an important role in pain signaling transmission in animal models. Low-level laser therapy (LLLT) is known to have an analgesic effect, but the mechanism is unclear. The aim of the study is to investigate the influence of LLLT on NO release and NOS synthesis in dorsal root ganglion (DRG) neurons, in order to find whether LLLI can ameliorate pain through modulating NO production at the cellular level. The results show that in stress conditions, the laser irradiation at 658 nm can modulate NO production in DRG neurons with soma diameter of about 20 μm in a short time after illumination, and affect NOS synthesis in a dose-dependent manner. It is demonstrated that LLLT might treat pain by altering NO release directly and indirectly in DRG neurons.

  17. Cobalt inhibits motility of axonal mitochondria and induces axonal degeneration in cultured dorsal root ganglion cells of rat.

    PubMed

    Kikuchi, Shin; Ninomiya, Takafumi; Kohno, Takayuki; Kojima, Takashi; Tatsumi, Haruyuki

    2017-06-27

    Cobalt is a trace element that localizes in the human body as cobalamin, also known as vitamin B12. Excessive cobalt exposure induces a peripheral neuropathy, the mechanisms of which are yet to be elucidated. We investigated how cobalt may affect mitochondrial motility in primary cultures of rat dorsal root ganglion (DRG). We observed mitochondrial motility by time-lapse imaging after DsRed2 tagging via lentivirus, mitochondrial structure using transmission electron microscopy (TEM), and axonal swelling using immunocytochemical staining. The concentration of cobaltous ion (Co(2+)) required to significantly suppress mitochondrial motility is lower than that required to induce axonal swelling following a 24-h treatment. Exposure to relatively low concentrations of Co(2+) for 48 h suppressed mitochondrial motility without leading to axonal swelling. TEM images indicated that Co(2+) induces mitochondrial destruction. Our results show that destruction of the axonal mitochondria precedes the axonal degeneration induced by Co(2+) exposure.

  18. Cross-excitation in dorsal root ganglia does not depend on close cell-to-cell apposition.

    PubMed

    Shinder, V; Amir, R; Devor, M

    1998-12-21

    About 90% of neurons in dorsal root ganglia (DRGs) of rats 2-5 weeks of age are depolarized and excited by impulse activity in neighboring neurons that share the same DRG. Synaptic contacts are extremely rare in DRGs, but instances of close membrane apposition between pairs of neuronal somata are not uncommon, especially in prenatal rats. Close membrane apposition could permit electrotonic interactions among neighboring DRG neurons. We carried out an ultrastructural examination of DRGs taken from rats 2-5 weeks of age and found that by this age < 2% of cells remain in close apposition with neighbors. The remainder are separated by one or two layers of satellite glial cytoplasm. It is, therefore, unlikely that close apposition between adjacent neurons contributes significantly to functional cross-excitation in the DRG.

  19. Extracorporeal shockwaves induce the expression of ATF3 and GAP-43 in rat dorsal root ganglion neurons.

    PubMed

    Murata, Ryo; Ohtori, Seiji; Ochiai, Nobuyasu; Takahashi, Norimasa; Saisu, Takashi; Moriya, Hideshige; Takahashi, Kazuhisa; Wada, Yuichi

    2006-07-30

    Although extracorporeal shockwave has been applied in the treatment of various diseases, the biological basis for its analgesic effect remains unclear. Therefore, we investigated the dorsal root ganglion neurons of rats following shockwave exposure to the footpad to elucidate its effect on the peripheral nervous system. We used activating transcription factor 3 (ATF3) and growth-associated phosphoprotein (GAP-43) as markers for nerve injury and axonal regeneration, respectively. The average number of neurons immunoreactive for ATF3 increased significantly in the treated rats at all experimental time points, with 78.3% of those neurons also exhibiting immunoreactivity for GAP-43. Shockwave exposure induced injury of the sensory nerve fibers within the exposed area. This phenomenon may be linked to the desensitization of the exposure area, not the cause of pain, considering clinical research with a particular absence of painful adverse effect. Subsequent active axonal regeneration may account for the reinnervation of exposed area and the amelioration of the desensitization.

  20. A dorsal root ganglia cell line derived from trisomy 16 fetal mice, a model for Down syndrome.

    PubMed

    Allen, David D; Cárdenas, Ana María; Arriagada, Christian; Bennett, Lori B; García, Carlos J; Caviedes, Raúl; Rapoport, Stanley I; Caviedes, Pablo

    2002-03-25

    We have established two immortalized cell lines from dorsal root ganglia of normal (G4b) and trisomy 16 mice (GT1), a model for Down syndrome. By immunohistochemistry, both cell lines exhibit neuronal traits and lack glial markers. GTl cells exhibited greater [3H]choline uptake than G4b cells. K+ and nicotine-mediated acetylcholine release was greater in GT1 cells. Basal intracellular Ca2+ concentration ([Ca2+]i) was significantly lower in GTl cells. More GTl cells responded to neurotransmitters with a transient [Ca2+]i increase compared to G4b cells, but both cell types showed similar amplitudes of [Ca2+]i responses. The results show that both cell lines retain neuronal characteristics and respond to specific neurotransmitter stimuli. Altered GT1 cell responses could be related to neuronal pathophysiology in Down's syndrome.

  1. Blood-nerve barrier: distribution of anionic sites on the endothelial plasma membrane and basal lamina of dorsal root ganglia.

    PubMed

    Bush, M S; Reid, A R; Allt, G

    1991-09-01

    Previous investigations of the blood-nerve barrier have correlated the greater permeability of ganglionic endoneurial vessels, compared to those of nerve trunks, with the presence of fenestrations and open intercellular junctions. Recent studies have demonstrated reduced endothelial cell surface charge in blood vessels showing greater permeability. To determine the distribution of anionic sites on the plasma membranes and basal laminae of endothelial cells in dorsal root ganglia, cationic colloidal gold and cationic ferritin were used. Electron microscopy revealed the existence of endothelial microdomains with differing labelling densities. Labelling indicated that caveolar and fenestral diaphragms and basal laminae are highly anionic at physiological pH, luminal plasma membranes and endothelial processes are moderately charged and abluminal plasma membranes are weakly anionic. Tracers did not occur in caveolae or cytoplasmic vesicles. In vitro tracer experiments at pH values of 7.3, 5.0, 3.5 and 2.0 indicated that the anionic charge on the various endothelial domains was contributed by chemical groups with differing pKa values. In summary, the labelling of ganglionic and sciatic nerve vessels was similar except for the heavy labelling of diaphragms in a minority of endoneurial vessels in ganglia. This difference is likely to account in part for the greater permeability of ganglionic endoneurial vessels. The results are discussed with regard to the blood-nerve and -brain barriers and vascular permeability in other tissues and a comparison made between the ultrastructure and anionic microdomains of epi-, peri- and endoneurial vessels of dorsal root ganglia and sciatic nerves.

  2. shRNA mediated knockdown of Nav1.7 in rat dorsal root ganglion attenuates pain following burn injury.

    PubMed

    Cai, Weihua; Cao, Jing; Ren, Xiuhua; Qiao, Liang; Chen, Xuemei; Li, Ming; Zang, Weidong

    2016-08-11

    Abnormal acute pain after burn injury still torments patients severely. In this study, we investigated that one voltage gated sodium channel Nav1.7 plays a vital role in lowering heat pain threshold after burn injury, and the hypothesis that knockdown of Nav1.7 attenuates pain following burn injury. Sixty eight adult male Sprague-Dawley rats were divided into 4 treatment groups: (1) sham, which hind paw was put on the room temperature metal plate for 15 s (2) burn model, which hind paw was put on the 85 °C metal plate for 15 s. (3) Burn injury + lentiviral vector -SCN9AsiRNA-GFP (LV- SCN9AsiRNA-GFP group, n = 18), which receive the DRG microinjection of LV- SCN9AsiRNA-GFP on the zero day. (4) Burn injury + lentiviral vector negative control (LV-NC-GFP group, n = 18), which receive the DRG microinjection of empty lentiviral vector on the zero day. Both mechanical and heat threshold were measured from day 1 to 21. Meanwhile, expression of sodium channels Nav1.7 in injured dorsal root ganglia were measured on post-operative days 7(POD 7). Rats exhibited decreased thresholds on both mechanical allodynia and thermal withdrawl latency, accompanied by increased Nav1.7 and c-fos expression in dorsal root ganglion (DRG). And knockdown of Nav1.7 in L5DRG led to the attenuation of burn injury-induced mechanical allodynia and thermal hyperalgesia in the rats. We provide evidence that shRNA mediated knockdown of Nav1.7 attenuates burn induced pain in rats as well as decreased the activiation of c-fos protein.

  3. A LIGHT AND ELECTRON MICROSCOPE STUDY OF LONG-TERM ORGANIZED CULTURES OF RAT DORSAL ROOT GANGLIA

    PubMed Central

    Bunge, Mary Bartlett; Bunge, Richard P.; Peterson, Edith R.; Murray, Margaret R.

    1967-01-01

    Dorsal root ganglia from fetal rats were explanted on collagen-coated coverslips and carried in Maximow double-coverslip assemblies for periods up to 3 months. These cultured ganglia were studied in the living state, in stained whole mounts, and in sections after OsO4 fixation and Epon embedment. From the central cluster of nerve cell bodies, neurites emerge to form a rich network of fascicles which often reach the edge of the carrying coverslip. The neurons resemble their in vivo counterparts in nuclear and cytoplasmic content and organization; e.g., they appear as "light" or "dark" cells, depending on the amount of cytoplasmic neurofilaments. Satellite cells form a complete investment around the neuronal soma and are themselves everywhere covered by basement membrane. The neuron-satellite cell boundary is complicated by spinelike processes arising from the neuronal soma. Neuron size, myelinated fiber diameter, and internode length in the cultures do not reach the larger of the values known for ganglion and peripheral nerve in situ (30). Unmyelinated and myelinated nerve fibers and associated Schwann cells and endoneurial and perineurial components are organized into typical fascicles. The relationship of the Schwann cell and its single myelinated fiber or numerous unmyelinated fibers and the properties of myelin, such as lamellar spacing, mesaxons, Schmidt-Lanterman clefts, nodes of Ranvier, and protuberances, mimic the in vivo pattern. It is concluded that cultivation of fetal rat dorsal root ganglia by this technique fosters maturation and long-term maintenance of all the elements that comprise this cellular community in vivo (except vascular components) and, furthermore, allows these various components to relate faithfully to one another to produce an organotypic model of sensory ganglion tissue. PMID:10976233

  4. The effects of anticonvulsants on 4-aminopyridine-induced bursting: in vitro studies on rat peripheral nerve and dorsal roots.

    PubMed Central

    Lees, G.

    1996-01-01

    1. Aminopyridines have been used as beneficial symptomatic treatments in a variety of neurological conditions including multiple sclerosis but have been associated with considerable toxicity in the form of abdominal pain, paraesthesias and (rarely) convulsions. 2. Extracellular and intracellular recording was used to characterize action potentials in rat sciatic nerves and dorsal roots and the effects of 4-aminopyridine (4-AP). 3. In sciatic nerve trunks, 1 mM 4-AP produced pronounced after potentials at room temperature secondary to regenerative firing in affected axons (5-10 spikes per stimulus). At physiological temperatures, after potentials (2-3 spikes) were greatly attenuated in peripheral axons. 4. 4-AP evoked more pronounced and prolonged after discharges in isolated dorsal roots at 37 degrees C (3-5.5 mV and 80-100 ms succeeded by a smaller inhibitory/depolarizing voltage shift) which were used to assess the effects of anticonvulsants. 5. Phenytoin, carbamazepine and lamotrigine dose-dependently reduced the area of 4-AP-induced after potentials at 100 and 320 microM but the amplitude of compound action potentials (evoked at 0.5 Hz) was depressed in parallel. 6. The tonic block of sensory action potentials by all three drugs (at 320 microM) was enhanced by high frequency stimulation (5-500 Hz). 7. The lack of selectivity of these frequency-dependent Na+ channel blockers for burst firing compared to low-frequency spikes, is discussed in contrast to their effects on 4-AP-induced seizures and paroxysmal activity in CNS tissue (which is associated with large and sustained depolarizing plateau potentials). 8. In conclusion, these in vitro results confirm the marked sensitivity of sensory axons to 4-AP (the presumptive basis for paraesthesias). Burst firing was not preferentially impaired at relatively high concentrations suggesting that anticonvulsants will not overcome the toxic peripheral actions of 4-AP in neurological patients. PMID:8821551

  5. Distribution of purinergic P2X receptors in the equine digit, cervical spinal cord and dorsal root ganglia.

    PubMed

    Zamboulis, D E; Senior, J M; Clegg, P D; Gallagher, J A; Carter, S D; Milner, P I

    2013-09-01

    Purinergic pathways are considered important in pain transmission, and P2X receptors are a key part of this system which has received little attention in the horse. The aim of this study was to identify and characterise the distribution of P2X receptor subtypes in the equine digit and associated vasculature and nervous tissue, including peripheral nerves, dorsal root ganglia and cervical spinal cord, using PCR, Western blot analysis and immunohistochemistry. mRNA signal for most of the tested P2X receptor subunits (P2X1-5, 7) was detected in all sampled equine tissues, whereas P2X6 receptor subunit was predominantly expressed in the dorsal root ganglia and spinal cord. Western blot analysis validated the specificity of P2X1-3, 7 antibodies, and these were used in immunohistochemistry studies. P2X1-3, 7 receptor subunits were found in smooth muscle cells in the palmar digital artery and vein with the exception of the P2X3 subunit that was present only in the vein. However, endothelial cells in the palmar digital artery and vein were positive only for P2X2 and P2X3 receptor subunits. Neurons and nerve fibres in the peripheral and central nervous system were positive for P2X1-3 receptor subunits, whereas glial cells were positive for P2X7 and P2X1 and 2 receptor subunits. This previously unreported distribution of P2X subtypes may suggest important tissue specific roles in physiological and pathological processes.

  6. Palmitoyl-DL-carnitine has calcium-dependent effects on cultured neurones from rat dorsal root ganglia.

    PubMed Central

    Stapleton, S. R.; Currie, K. P.; Scott, R. H.; Bell, B. A.

    1992-01-01

    1. The effects of palmitoyl-DL-carnitine (0.01 to 1 mM) on whole cell voltage-activated calcium channel currents carried by calcium or barium and Ca(2+)-activated chloride currents were studied in cultured neurones from rat dorsal root ganglia. 2. Palmitoyl-DL-carnitine applied to the extracellular environment or intracellularly via the patch solution reduced Ca2+ currents activated over a wide voltage range from a holding potential of -90 mV. Inhibition of high voltage activated Ca2+ channel currents was dependent on intracellular Ca2+ buffering and was reduced by increasing the EGTA concentration from 2 to 10 mM in the patch solution. Barium currents were significantly less sensitive to palmitoyl-DL-carnitine than Ca2+ currents. 3. The amplitude of Ca(2+)-activated Cl- tail currents was reduced by palmitoyl-DL-carnitine. However, the duration of these Cl- currents was greatly prolonged by palmitoyl-DL-carnitine, suggesting slower removal of free Ca2+ from the cytoplasm following Ca2+ entry through voltage-activated channels. 4. Palmitoyl-DL-carnitine evoked Ca(2+)-dependent inward currents which could be promoted by activation of the residual voltage-activated Ca2+ currents and attenuated by intracellular application of EGTA. 5. We conclude that palmitoyl-DL-carnitine reduced the efficiency of intracellular Ca2+ handling in cultured dorsal root ganglion neurones and resulted in enhancement of Ca(2+)-dependent events including inactivation of voltage-activated Ca2+ currents. The activation of inward currents by palmitolyl-DL-carnitine may involve Ca(2+)-induced Ca2+ release from intracellular stores, or direct interaction of palmitoyl-DL-carnitine with Ca2+ stores. PMID:1334752

  7. A comparison of peripheral and central axotomy effects on neurofilament and tubulin gene expression in rat dorsal root ganglion neurons

    SciTech Connect

    Wong, J.; Oblinger, M.M. )

    1990-07-01

    The expression of major cytoskeletal protein mRNAs was studied in adult rat dorsal root ganglion (DRG) neurons after crushing either their central or peripheral branch axons. mRNA levels in DRG neurons were examined by quantitative in situ hybridization with radiolabeled cDNA probes specific for the low-molecular-weight neurofilament protein (NF-L) and beta-tubulin. The large-sized (greater than 1000 microns 2) neurons which give rise to myelinated axons in lumbar ganglia (L4 and L5) were studied 1 d through 8 weeks after either dorsal root or sciatic nerve crush. NF-L and beta-tubulin mRNA levels in axotomized DRG neurons were compared to those in contralateral control DRG neurons, as well as to those in normal (completely untreated) DRG cells. In the case of NF-L mRNA, changes were observed after central as well as peripheral branch axotomy and the time course and magnitude of changes were similar after both types of axotomy. NF-L mRNA levels initially decreased (first 2 weeks after crush) and then began to return towards control levels at longer survival times. Similar, but less pronounced, changes in NF-L mRNA levels also occurred in contralateral DRG neurons (which were uninjured); the changes in contralateral neurons were not simply a result of surgical stress since no changes in NF-L mRNA levels were observed in sham-operated DRG neurons. In the case of tubulin mRNA, changes were observed after central as well as peripheral branch axotomy by in situ hybridization, but the time course and magnitude of changes were different after each type of axotomy.

  8. Effects of neomycin on high-threshold Ca(2+) currents and tetrodotoxin-resistant Na(+) currents in rat dorsal root ganglion neuron.

    PubMed

    Zhou, Yu; Zhao, Zhi-Qi

    2002-08-16

    High-threshold Ca(2+) channels and tetrodotoxin-resistant Na(+) channels are highly expressed in small dorsal root ganglion neurons. In acutely isolated rat dorsal root ganglion neurons, the effects of neomycin, one of the aminoglycoside antibiotics, on high-threshold Ca(2+) currents and tetrodotoxin-resistant Na(+) currents were examined using whole-cell patch recording. We showed for the first time that neomycin dose-dependently inhibited peak high-threshold Ca(2+) currents and peak tetrodotoxin-resistant Na(+) currents with half-maximal inhibitory concentrations at 3.69 microM (n=20) and 1213.44 microM (n=25), respectively. Inactivation properties of high-threshold Ca(2+) currents and activation properties of tetrodotoxin-resistant Na(+) currents were also affected by neomycin with reduction of excitability of small dorsal root ganglion neurons. Half-maximal inactivation voltage of high-threshold Ca(2+) currents was -45.56 mV before and -50.46 mV after application of neomycin (n=10). Half-maximal activation voltage of tetrodotoxin-resistant Na(+) currents was -19.93 mV before and -11.19 mV after administration of neomycin (n=15). These results suggest that neomycin can inhibit high-threshold Ca(2+) currents and tetrodotoxin-resistant Na(+) currents in small dorsal root ganglion neurons, which may contribute to neomycin-induced peripheral and central analgesia.

  9. Bladder volume-dependent excitatory and inhibitory influence of lumbosacral dorsal and ventral roots on bladder activity in rats.

    PubMed

    Sugaya, Kimio; de Groat, William C

    2007-08-01

    This study was undertaken to examine the role of the afferent and efferent pathways of the lumbosacral spinal nerve roots in the tonic control of bladder activity. Changes of isovolumetric bladder activity were recorded in 21 sympathectomized female rats under urethane anesthesia following transection of the dorsal (DRT) and ventral (VRT) lumbosacral spinal roots, and after intraperitoneal administration of hexamethonium. DRT altered the baseline intravesical pressure in a bladder volume-dependent manner in each animal. The percent change of baseline pressure after VRT following DRT was also dependent upon bladder volume. The percent change of baseline pressure after VRT alone was similarly dependent on bladder volume, but not after VRT followed by DRT. The percent change of baseline intravesical pressure (y)(-9 to +8 cm H(2)O, -56 to +46%) after DRT and VRT depended upon bladder volume (x)(y = 44.7 x -40.4) in all rats. Hexamethonium increased the amplitude of small myogenic bladder contractions after DRT and VRT. In conclusion, the bladder is tonically excited or inhibited by a local reflex pathway and by a parasympathetic reflex pathway that depends on connections with the lumbosacral spinal cord and the pelvic nerves. Both reflex mechanisms are influenced by bladder volume.

  10. The effects of ropivacaine hydrochloride on the expression of CaMK II mRNA in the dorsal root ganglion neurons.

    PubMed

    Wen, Xianjie; Lai, Xiaohong; Li, Xiaohong; Zhang, Tao; Liang, Hua

    2016-12-01

    In this study, we identified the subtype of Calcium/calmodulin-dependent protein kinase II (CaMK II) mRNA in dorsal root ganglion neurons and observed the effects of ropivacaine hydrochloride in different concentration and different exposure time on the mRNA expression. Dorsal root ganglion neurons were isolated from the SD rats and cultured in vitro. The mRNA of the CaMK II subtype in dorsal root ganglion neurons were detected by real-time PCR. As well as, the dorsal root ganglion neurons were treated with ropivacaine hydrochloride in different concentration (1mM,2mM, 3mM and 4mM) for the same exposure time of 4h, or different exposure time (0h,2h,3h,4h and 6h) at the same concentration(3mM). The changes of the mRNA expression of the CaMK II subtype were observed with real-time PCR. All subtype mRNA of the CaMK II, CaMK IIα, CaMK IIβ, CaMK II δ, CaMK IIγ, can be detected in dorsal root ganglion neurons. With the increased of the concentration and exposure time of the ropivacaine hydrochloride, all the subtype mRNA expression increased. Ropivacaine hydrochloride up-regulate the CaMK IIβ, CaMK IIδ, CaMK IIg mRNA expression with the concentration and exposure time increasing. The nerve blocking or the neurotoxicity of the ropivacaine hydrochloride maybe involved with CaMK II.

  11. Conantokin G-induced changes in the chemical coding of dorsal root ganglion neurons supplying the porcine urinary bladder.

    PubMed

    Bossowska, A; Majewski, M

    2012-01-01

    Conantokin G (CTG), isolated from the venom of the marine cone snail Conus geographus, is an antagonist of N-methyl-d-aspartate receptors (NMDARs), the activation of which, especially those located on the central afferent terminals and dorsal horn neurons, leads to hypersensitivity and pain. Thus, CTG blocking of NMDARs, has an antinociceptive effect, particularly in the case of neurogenic pain treatment. As many urinary bladder disorders are caused by hyperactivity of sensory bladder innervation, it seems useful to estimate the influence of CTG on the plasticity of sensory neurons supplying the organ. Retrograde tracer Fast Blue (FB) was injected into the urinary bladder wall of six juvenile female pigs. Three weeks later, intramural bladder injections of CTG (120 microg per animal) were carried out in all animals. After a week, dorsal root ganglia of interest were harvested from all animals and neurochemical characterization of FB+ neurons was performed using a routine double-immunofluorescence labeling technique on 10-microm-thick cryostat sections. CTG injections led to a significant decrease in the number of FB+ neurons containing substance P (SP), pituitary adenylate cyclase activating polypeptide (PACAP), somatostatin (SOM), calbindin (CB) and nitric oxide synthase (NOS) when compared with healthy animals (20% vs. 45%, 13% vs. 26%, 1.3% vs. 3%, 1.2 vs. 4% and 0.9% vs. 6% respectively) and to an increase in the number of cells immunolabelled for galanin (GAL, 39% vs. 6.5%). These data demonstrated that CTG changed the chemical coding of bladder sensory neurons, thus indicating that CTG could eventually be used in the therapy of selected neurogenic bladder illnesses.

  12. Activation and circuitry of uterine-cervix-related neurons in the lumbosacral dorsal root ganglia and spinal cord at parturition.

    PubMed

    Puder, B A; Papka, R E

    2005-12-15

    Stimulation of the uterine cervix at parturition activates neural circuits involving primary sensory nerves and supraspinally projecting neurons of the lumbosacral spinal cord, resulting in output of hypothalamic neurohormones. Dorsal root ganglia (DRG) and spinal neurons of these circuits are not well-characterized. The objectives of this study were to detail the activation of DRG and spinal neurons of the L6/S1 levels that are stimulated at late pregnancy, verify hypothalamic projections of activated spinal neurons, and determine whether activated neurons express estrogen receptor-alpha (ERalpha). Expression of phosphorylated cyclic-AMP response element-binding protein (PCREB) and Fos immunohistochemistry were used to "mark" activated DRG and spinal neurons, respectively. Retrograde tracing identified uterine-cervix-related and spinohypothalamic neurons. Baseline PCREB expression in the DRG increased during pregnancy and peaked during the last trimester. Some PCREB-expressing neurons contained retrograde tracer identifying them as cervix-related neurons. Fos-expressing neurons were few in spinal cords of nonpregnant and day 22 pregnant rats but were numerous in parturient animals. Some Fos-expressing neurons located in the dorsal half of the spinal cord contained retrograde tracer identifying them as spinohypothalamic neurons. Some DRG neurons expressing PCREB also expressed ERalpha, and some spinal neurons activated at parturition projected axons to the hypothalamus and expressed ERalpha. These results indicate that DRG and spinal cord neurons are activated at parturition; that those in the spinal cord are present in areas involved in autonomic and sensory processing; that some spinal neurons project axons to the hypothalamus, ostensibly part of a neuroendocrine reflex; and that sensory and spinal neurons can respond to estrogens. Moreover, some activated sensory neurons may be involved in the animal's perception of labor pain.

  13. Permanent loss of fore-paw grasping requires complete deprivation of afferent input from a minimum of four dorsal roots of the rat brachial plexus.

    PubMed

    Ibrahim, Ahmed G; Raisman, Geoffrey; Li, Ying

    2009-01-01

    Dorsal roots from the 6th cervical to the 1st thoracic segment were sectioned flush with the surface of the spinal cord on one side. For 3 weeks before and 8 weeks after surgery the rats were filmed once a week during two successive climbs up a 1 m grid. Before surgery the fore-paws of normal rats grasped the grid bar for a mean of 7.0+/-0.1 times per climb. After complete section of C6 to T1 dorsal roots on one side there was a major deficit in the ipsilateral fore-paw in locating the grid bars, and grasping was almost totally abolished (mean of 0.1+/-0.06 grasps per climb). The failure of the rats to locate or to grasp the bars persisted unchanged for the entire test period. Rats with section of C6 to C8, but sparing T1, showed a similar but milder pattern of deficit. Section of any two adjacent cervical roots caused only minor deficits. Section of any single root alone caused no detectable deficit in climbing. The consistent loss of grasping after section of the 4 dorsal roots from C6 to T1 provides a promising model for assessing putative regenerative therapies.

  14. Dopamine modulation of transient receptor potential vanilloid type 1 (TRPV1) receptor in dorsal root ganglia neurons

    PubMed Central

    Chakraborty, Saikat; Rebecchi, Mario; Kaczocha, Martin

    2016-01-01

    Key points Transient receptor potential vanilloid type 1 (TRPV1) receptors transduce noxious thermal stimuli and are responsible for the thermal hyperalgesia associated with inflammatory pain.A large population of dorsal root ganglia (DRG) neurons, including the C low threshold mechanoreceptors (C‐LTMRs), express tyrosine hydroxylase, and probably release dopamine.We found that dopamine and SKF 81297 (an agonist at D1/D5 receptors), but not quinpirole (an agonist at D2 receptors), downregulate the activity of TRPV1 channels in DRG neurons.The inhibitory effect of SKF 81297 on TRPV1 channels was strongly dependent on external calcium and preferentially linked to calcium–calmodulin‐dependent protein kinase II (CaMKII).We suggest that modulation of TRPV1 channels by dopamine in nociceptive neurons may represent a way for dopamine to modulate incoming noxious stimuli. Abstract The transient receptor potential vanilloid type 1 (TRPV1) receptor plays a key role in the modulation of nociceptor excitability. To address whether dopamine can modulate the activity of TRPV1 channels in nociceptive neurons, the effects of dopamine and dopamine receptor agonists were tested on the capsaicin‐activated current recorded from acutely dissociated small diameter (<27 μm) dorsal root ganglia (DRG) neurons. Dopamine or SKF 81297 (an agonist at D1/D5 receptors), caused inhibition of both inward and outward currents by ∼60% and ∼48%, respectively. The effect of SKF 81297 was reversed by SCH 23390 (an antagonist at D1/D5 receptors), confirming that it was mediated by activation of D1/D5 dopamine receptors. In contrast, quinpirole (an agonist at D2 receptors) had no significant effect on the capsaicin‐activated current. Inhibition of the capsaicin‐activated current by SKF 81297 was mediated by G protein coupled receptors (GPCRs), and highly dependent on external calcium. The inhibitory effect of SKF 81297 on the capsaicin‐activated current was not affected when

  15. Chronic Compression of the Dorsal Root Ganglion Enhances Mechanically Evoked Pain Behavior and the Activity of Cutaneous Nociceptors in Mice

    PubMed Central

    Wang, Tao; Hurwitz, Olivia; Shimada, Steven G.; Qu, Lintao; Fu, Kai; Zhang, Pu; Ma, Chao; LaMotte, Robert H.

    2015-01-01

    Radicular pain in humans is usually caused by intraforaminal stenosis and other diseases affecting the spinal nerve, root, or dorsal root ganglion (DRG). Previous studies discovered that a chronic compression of the DRG (CCD) induced mechanical allodynia in rats and mice, with enhanced excitability of DRG neurons. We investigated whether CCD altered the pain-like behavior and also the responses of cutaneous nociceptors with unmyelinated axons (C-fibers) to a normally aversive punctate mechanical stimulus delivered to the hairy skin of the hind limb of the mouse. The incidence of a foot shaking evoked by indentation of the dorsum of foot with an aversive von Frey filament (tip diameter 200 μm, bending force 20 mN) was significantly higher in the foot ipsilateral to the CCD surgery as compared to the contralateral side on post-operative days 2 to 8. Mechanically-evoked action potentials were electrophysiologically recorded from the L3 DRG, in vivo, from cell bodies visually identified as expressing a transgenically labeled fluorescent marker (neurons expressing either the receptor MrgprA3 or MrgprD). After CCD, 26.7% of MrgprA3+ and 32.1% MrgprD+ neurons exhibited spontaneous activity (SA), while none of the unoperated control neurons had SA. MrgprA3+ and MrgprD+ neurons in the compressed DRG exhibited, in comparison with neurons from unoperated control mice, an increased response to the punctate mechanical stimuli for each force applied (6, 20, 40, and 80 mN). We conclude that CCD produced both a behavioral hyperalgesia and an enhanced response of cutaneous C-nociceptors to aversive punctate mechanical stimuli. PMID:26356638

  16. Functional properties and toxin pharmacology of a dorsal root ganglion sodium channel viewed through its voltage sensors

    PubMed Central

    Puopolo, Michelino; Martin-Eauclaire, Marie-France; Bean, Bruce P.

    2011-01-01

    The voltage-activated sodium (Nav) channel Nav1.9 is expressed in dorsal root ganglion (DRG) neurons where it is believed to play an important role in nociception. Progress in revealing the functional properties and pharmacological sensitivities of this non-canonical Nav channel has been slow because attempts to express this channel in a heterologous expression system have been unsuccessful. Here, we use a protein engineering approach to dissect the contributions of the four Nav1.9 voltage sensors to channel function and pharmacology. We define individual S3b–S4 paddle motifs within each voltage sensor, and show that they can sense changes in membrane voltage and drive voltage sensor activation when transplanted into voltage-activated potassium channels. We also find that the paddle motifs in Nav1.9 are targeted by animal toxins, and that these toxins alter Nav1.9-mediated currents in DRG neurons. Our results demonstrate that slowly activating and inactivating Nav1.9 channels have functional and pharmacological properties in common with canonical Nav channels, but also show distinctive pharmacological sensitivities that can potentially be exploited for developing novel treatments for pain. PMID:21670206

  17. Pine Oil Effects on Chemical and Thermal Injury in Mice and Cultured Mouse Dorsal Root Ganglion Neurons

    PubMed Central

    Clark, SP; Bollag, WB; Westlund, KN; Ma, F; Falls, G; Xie, D; Johnson, M; Isales, CM; Bhattacharyya, MH

    2013-01-01

    A commercial resin-based pine oil derived from Pinus palustris and Pinus elliottii was the major focus of this investigation. Extracts of pine resins, needles and bark are folk medicines commonly used to treat skin ailments, including burns. The American Burn Association estimates that 500,000 people with burn injuries receive medical treatment each year; one-half of US burn victims are children, most with scald burns. This systematic study was initiated as follow-up to personal anecdotal evidence acquired over more than 10 years by MH Bhattacharyya regarding pine oil’s efficacy for treating burns. The results demonstrate that pine oil counteracted dermal inflammation in both a mouse ear model of contact irritant-induced dermal inflammation and a 2nd degree scald burn to the mouse paw. Furthermore, pine oil significantly counteracted the tactile allodynia and soft tissue injury caused by the scald burn. In mouse dorsal root ganglion (DRG) neuronal cultures, pine oil added to the medium blocked ATP-activated, but not capsaicin-activated, pain pathways, demonstrating specificity. These results together support the hypothesis that a pine-oil-based treatment can be developed to provide effective in-home care for 2nd degree burns. PMID:23595692

  18. Effective gene expression in the rat dorsal root ganglia with a non-viral vector delivered via spinal nerve injection

    PubMed Central

    Chang, Ming-Fong; Hsieh, Jung-Hsien; Chiang, Hao; Kan, Hung-Wei; Huang, Cho-Min; Chellis, Luke; Lin, Bo-Shiou; Miaw, Shi-Chuen; Pan, Chun-Liang; Chao, Chi-Chao; Hsieh, Sung-Tsang

    2016-01-01

    Delivering gene constructs into the dorsal root ganglia (DRG) is a powerful but challenging therapeutic strategy for sensory disorders affecting the DRG and their peripheral processes. The current delivery methods of direct intra-DRG injection and intrathecal injection have several disadvantages, including potential injury to DRG neurons and low transfection efficiency, respectively. This study aimed to develop a spinal nerve injection strategy to deliver polyethylenimine mixed with plasmid (PEI/DNA polyplexes) containing green fluorescent protein (GFP). Using this spinal nerve injection approach, PEI/DNA polyplexes were delivered to DRG neurons without nerve injury. Within one week of the delivery, GFP expression was detected in 82.8% ± 1.70% of DRG neurons, comparable to the levels obtained by intra-DRG injection (81.3% ± 5.1%, p = 0.82) but much higher than those obtained by intrathecal injection. The degree of GFP expression by neurofilament(+) and peripherin(+) DRG neurons was similar. The safety of this approach was documented by the absence of injury marker expression, including activation transcription factor 3 and ionized calcium binding adaptor molecule 1 for neurons and glia, respectively, as well as the absence of behavioral changes. These results demonstrated the efficacy and safety of delivering PEI/DNA polyplexes to DRG neurons via spinal nerve injection. PMID:27748450

  19. FGF and BMP derived from dorsal root ganglia regulate blastema induction in limb regeneration in Ambystoma mexicanum.

    PubMed

    Satoh, Akira; Makanae, Aki; Nishimoto, Yurie; Mitogawa, Kazumasa

    2016-09-01

    Urodele amphibians have a remarkable organ regeneration ability that is regulated by neural inputs. The identification of these neural inputs has been a challenge. Recently, Fibroblast growth factor (Fgf) and Bone morphogenic protein (Bmp) were shown to substitute for nerve functions in limb and tail regeneration in urodele amphibians. However, direct evidence of Fgf and Bmp being secreted from nerve endings and regulating regeneration has not yet been shown. Thus, it remained uncertain whether they were the nerve factors responsible for successful limb regeneration. To gather experimental evidence, the technical difficulties involved in the usage of axolotls had to be overcome. We achieved this by modifying the electroporation method. When Fgf8-AcGFP or Bmp7-AcGFP was electroporated into the axolotl dorsal root ganglia (DRG), GFP signals were detectable in the regenerating limb region. This suggested that Fgf8 and Bmp7 synthesized in neural cells in the DRG were delivered to the limbs through the long axons. Further knockdown experiments with double-stranded RNA interference resulted in impaired limb regeneration ability. These results strongly suggest that Fgf and Bmp are the major neural inputs that control the organ regeneration ability. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Controlled release of 6-aminonicotinamide from aligned, electrospun fibers alters astrocyte metabolism and dorsal root ganglia neurite outgrowth

    NASA Astrophysics Data System (ADS)

    Schaub, Nicholas J.; Gilbert, Ryan J.

    2011-08-01

    Following central nervous system (CNS) injury, activated astrocytes form a glial scar that inhibits the migration of axons ultimately leading to regeneration failure. Biomaterials developed for CNS repair can provide local delivery of therapeutics and/or guidance mechanisms to encourage cell migration into damaged regions of the brain or spinal cord. Electrospun fibers are a promising type of biomaterial for CNS injury since these fibers can direct cellular and axonal migration while slowly delivering therapy to the injury site. In this study, it was hypothesized that inclusion of an anti-metabolite, 6-aminonicotinamide (6AN), within poly-l-lactic acid electrospun fibers could attenuate astrocyte metabolic activity while still directing axonal outgrowth. Electrospinning parameters were varied to produce highly aligned electrospun fibers that contained 10% or 20% (w/w) 6AN. 6AN release from the fiber substrates occurred continuously over 2 weeks. Astrocytes placed onto drug-releasing fibers were less active than those cultured on scaffolds without 6AN. Dorsal root ganglia placed onto control and drug-releasing scaffolds were able to direct neurites along the aligned fibers. However, neurite outgrowth was stunted by fibers that contained 20% 6AN. These results show that 6AN release from aligned, electrospun fibers can decrease astrocyte activity while still directing axonal outgrowth.

  1. Real-time control of hind limb functional electrical stimulation using feedback from dorsal root ganglia recordings

    NASA Astrophysics Data System (ADS)

    Bruns, Tim M.; Wagenaar, Joost B.; Bauman, Matthew J.; Gaunt, Robert A.; Weber, Douglas J.

    2013-04-01

    Objective. Functional electrical stimulation (FES) approaches often utilize an open-loop controller to drive state transitions. The addition of sensory feedback may allow for closed-loop control that can respond effectively to perturbations and muscle fatigue. Approach. We evaluated the use of natural sensory nerve signals obtained with penetrating microelectrode arrays in lumbar dorsal root ganglia (DRG) as real-time feedback for closed-loop control of FES-generated hind limb stepping in anesthetized cats. Main results. Leg position feedback was obtained in near real-time at 50 ms intervals by decoding the firing rates of more than 120 DRG neurons recorded simultaneously. Over 5 m of effective linear distance was traversed during closed-loop stepping trials in each of two cats. The controller compensated effectively for perturbations in the stepping path when DRG sensory feedback was provided. The presence of stimulation artifacts and the quality of DRG unit sorting did not significantly affect the accuracy of leg position feedback obtained from the linear decoding model as long as at least 20 DRG units were included in the model. Significance. This work demonstrates the feasibility and utility of closed-loop FES control based on natural neural sensors. Further work is needed to improve the controller and electrode technologies and to evaluate long-term viability.

  2. An Efficient Method for Dorsal Root Ganglia Neurons Purification with a One-Time Anti-Mitotic Reagent Treatment

    PubMed Central

    Liu, Rui; Lin, Gou; Xu, Hanpeng

    2013-01-01

    Background The dorsal root ganglia (DRG) neuron is an invaluable tool in axon growth, growth factor regulation, myelin formation and myelin-relevant researches. The purification of DRG neurons is a key step in these studies. Traditionally, purified DRG neurons were obtained in two weeks after exposure to several rounds of anti-mitotic reagent. Methods and Results In this report, a novel, simple and efficient method for DRG purification is presented. DRG cultures were treated once with a high-dose anti-mitotic reagent cocktail for 72 hours. Using this new method, DRG neurons were obtained with 99% purification within 1 week. We confirmed that the neurite growth and the viability of the purified DRG neurons have no difference from the DRG neurons purified by traditional method. Furthermore, P0 and MBP expression was observed in myelin by immunocytochemistry in the DRG/SC co-culture system. The formation of mature node of Ranvier in DRG-Schwann cell co-culture system was observed using anti-Nav 1.6 and anti-caspr antibody. Conclusion and Significance The results indicate that this high dose single treatment did not compromise the capacity of DRG neurons for myelin formation in the DRG/SC co-culture system. In conclusion, a convenient approach for purifying DRG neurons was developed which is time-saving and high-efficiency. PMID:23565257

  3. Slit-Robo GTPase-activating proteins are differentially expressed in murine dorsal root ganglia: modulation by peripheral nerve injury.

    PubMed

    Chen, Zhi-Bing; Zhang, Hai-Ying; Zhao, Jiu-Hong; Zhao, Wei; Zhao, Dan; Zheng, Lin-Feng; Zhang, Xian-Fang; Liao, Xiao-Ping; Yi, Xi-Nan

    2012-04-01

    The Slit-Robo GTPase-activating proteins (srGAPs) play an important role in neurite outgrowth and axon guidance; however, little is known about its role in nerve regeneration after injury. Here, we studied the expression of srGAPs in mouse dorsal root ganglia (DRG) following sciatic nerve transection (SNT) using morphometric and immunohistochemical techniques. Reverse transcriptase polymerase chain reaction and Western blot analysis indicated that srGAP1 and srGAP3, but not srGAP2, were expressed in normal adult DRG. Following unilateral SNT, elevated mRNA and protein levels of srGAP1 and srGAP3 were detected in the ipsilateral relative to contralateral L(3-4) DRGs from day 3 to day 14. Immunohistochemical results showed that srGAP1 and srGAP3 were largely expressed in subpopulations of DRG neurons in naïve DRGs. However, after SNT, srGAP3 in neurons was significantly increased in the ipsilateral relative to contralateral DRGs, which peaked at day 7 to day 14. Interestingly, DRG neurons with strong srGAP3 labeling also coexpressed Robo2 after peripheral nerve injury. These results suggest that srGAPs are differentially expressed in murine DRG and srGAP3 are the predominant form. Moreover, srGAP3 may participate in Slit-Robo signaling in response to peripheral nerve injury or the course of nerve regeneration.

  4. Substance P release evoked by capsaicin or potassium from rat cultured dorsal root ganglion neurons is conversely modulated with bradykinin.

    PubMed

    Tang, He-Bin; Inoue, Atsuko; Iwasa, Mikiko; Hide, Izumi; Nakata, Yoshihiro

    2006-06-01

    To clarify the molecular mechanism of substance P (SP) release from dorsal root ganglion (DRG) neurons, we investigated the involvement of several intracellular effectors in the regulation of SP release evoked by capsaicin, potassium or/and bradykinin. Bradykinin-evoked SP release from cultured adult rat DRG neurons was attenuated by either the mitogen-activated protein kinase kinase (MEK) inhibitor (U0126) or cycloheximide. As the long-term exposure of DRG neurons to bradykinin (3 h) resulted in extracellular signal-regulated kinase (ERK) phosphorylation at an early stage and thereafter induced cyclooxygenase-2 (COX-2) protein expression, which both contribute to the SP release triggered by bradykinin B2 receptor. The long-term exposure of DRG neurons to bradykinin enhanced the SP release by capsaicin, but attenuated that by potassium. Interestingly, the inositol 1,4,5-triphosphate (IP3)-induced calcium release blocker [2-aminoethyl diphenylborinate (2-APB)] not only inhibited the potassium-evoked SP release, but also completely abolished the enhancement of capsaicin-induced SP release by bradykinin from cultured DRG neurons. Together, these findings suggest that the molecular mechanisms of SP release by bradykinin involve the activation of MEK, and also require the de novo protein synthesis of COX-2 in DRG neurons. The IP3-dependent calcium release could be involved in the processes of the regulation by bradykinin of capsaicin-triggered SP release.

  5. Role of TRPM2 cation channels in dorsal root ganglion of rats after experimental spinal cord injury.

    PubMed

    Naziroğlu, Mustafa; Uğuz, Abdülhadi Cihangir; Ismailoğlu, Özgür; Çiğ, Bilal; Özgül, Cemil; Borcak, Muhammed

    2013-12-01

    We sought to determine the contribution of oxidative stress-dependent activation of TRPM2 and L-type voltage-gated Ca(2+) channels (VGCC) in dorsal root ganglion (DRG) neurons of rats after spinal cord injury (SCI). The rats were divided into 4 groups: control; sham control; SCI; and SCI+nimodipine groups. The neurons of the SCI groups were also incubated with non-specific TRPM2 channel blockers, 2-aminoethoxydiphenylborate (2-APB) and N-(p-amylcinnamoyl)anthranilic acid (ACA), before H2 O2 stimulation. The [Ca(2+) ]i concentrations were higher in the SCI group than in the control groups, although their concentrations were decreased by nimodipine and 2-APB. The H2 O2 -induced TRPM2 current densities in patch-clamp experiments were decreased by ACA and 2-APB incubation. In the nimodipine group, the TRPM2 channels of neurons were not activated by H2 O2 or cumene hydroperoxide. Increased Ca(2+) influx and currents in DRG neurons after spinal injury indicated TRPM2 and voltage-gated Ca(2+) channel activation. Copyright © 2013 Wiley Periodicals, Inc.

  6. Regulation of Nav1.7: A Conserved SCN9A Natural Antisense Transcript Expressed in Dorsal Root Ganglia.

    PubMed

    Koenig, Jennifer; Werdehausen, Robert; Linley, John E; Habib, Abdella M; Vernon, Jeffrey; Lolignier, Stephane; Eijkelkamp, Niels; Zhao, Jing; Okorokov, Andrei L; Woods, C Geoffrey; Wood, John N; Cox, James J

    2015-01-01

    The Nav1.7 voltage-gated sodium channel, encoded by SCN9A, is critical for human pain perception yet the transcriptional and post-transcriptional mechanisms that regulate this gene are still incompletely understood. Here, we describe a novel natural antisense transcript (NAT) for SCN9A that is conserved in humans and mice. The NAT has a similar tissue expression pattern to the sense gene and is alternatively spliced within dorsal root ganglia. The human and mouse NATs exist in cis with the sense gene in a tail-to-tail orientation and both share sequences that are complementary to the terminal exon of SCN9A/Scn9a. Overexpression analyses of the human NAT in human embryonic kidney (HEK293A) and human neuroblastoma (SH-SY5Y) cell lines show that it can function to downregulate Nav1.7 mRNA, protein levels and currents. The NAT may play an important role in regulating human pain thresholds and is a potential candidate gene for individuals with chronic pain disorders that map to the SCN9A locus, such as Inherited Primary Erythromelalgia, Paroxysmal Extreme Pain Disorder and Painful Small Fibre Neuropathy, but who do not contain mutations in the sense gene. Our results strongly suggest the SCN9A NAT as a prime candidate for new therapies based upon augmentation of existing antisense RNAs in the treatment of chronic pain conditions in man.

  7. Botulinum toxin type A reduces TRPV1 expression in the dorsal root ganglion in rats with adjuvant-arthritis pain.

    PubMed

    Fan, Chenglei; Chu, Xiao; Wang, Lin; Shi, Hao; Li, Tieshan

    2017-07-01

    Arthritis pain affects people's long-term health, and recent studies have demonstrated that transient receptor potential vanilloid type 1 (TRPV1) plays a crucial role in arthritis pain. In addition, Pre-clinical evidence indicated that botulinum toxin type A (BoNT/A) has antinociceptive effect. The present study investigated the causality between the antinociceptive effects of BoNT/A and the expression of TRPV1 in dorsal root ganglion (DRG) in rats with adjuvant-arthritis pain. The results showed that BoNT/A significantly reduced adjuvant-arthritis nociceptive behaviors in a dose-dependent manner. Furthermore, the BoNT/A cleaved synaptosomal-associated protein of 25 kDa (cl-SNAP-25) was detected in the DRG using immunofluorescence after intra-articular administration. Although BoNT/A significantly reduced the protein levels of TRPV1, there were no significant changes in the mRNA levels of TRPV1 between CFA and BoNT/A (1U, 3U, 10U) group after BoNT/A retrograde axonal transport into the DRG with quantitative RT-PCR. This research provides evidence that the antinociceptive mechanism of BoNT/A might be mediated by reduction of TRPV1 expression through inhibition of its plasma membrane trafficking after intra-articular administration. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Enhanced adenoviral gene delivery to motor and dorsal root ganglion neurons following injection into demyelinated peripheral nerves.

    PubMed

    Zhang, Yongjie; Zheng, Yiyan; Zhang, Yi Ping; Shields, Lisa B E; Hu, Xiaoling; Yu, Panpan; Burke, Darlene A; Wang, Heming; Jun, Cai; Byers, Jonathan; Whittemore, Scott R; Shields, Christopher B

    2010-08-15

    Injection of viral vectors into peripheral nerves may transfer specific genes into their dorsal root ganglion (DRG) neurons and motoneurons. However, myelin sheaths of peripheral axons block the entry of viral particles into nerves. We studied whether mild, transient peripheral nerve demyelination prior to intraneural viral vector injection would enhance gene transfer to target DRG neurons and motoneurons. The right sciatic nerve of C57BL/6 mice was focally demyelinated with 1% lysolecithin, and the left sciatic nerve was similarly injected with saline (control). Five days after demyelination, 0.5 microl of Ad5-GFP was injected into both sciatic nerves at the site of previous injection. The effectiveness of gene transfer was evaluated by counting GFP(+) neurons in the DRGs and ventral horns. After peripheral nerve demyelination, there was a fivefold increase in the number of infected DRG neurons and almost a 15-fold increase in the number of infected motoneurons compared with the control, nondemyelinated side. Focal demyelination reduced the myelin sheath barrier, allowing greater virus-axon contact. Increased CXADR expression on the demyelinated axons facilitated axoplasmic viral entry. No animals sustained any prolonged neurological deficits. Increased gene delivery into DRG neurons and motoneurons may provide effective treatment for amyotrophic lateral sclerosis, pain, and spinal cord injury.

  9. Channelrhodopsin-2-expressed dorsal root ganglion neurons activates calcium channel currents and increases action potential in spinal cord.

    PubMed

    Zhang, Yi; Yue, Jing; Ai, Midan; Ji, Zhigang; Liu, Zhiguo; Cao, Xuehong; Li, Li

    2014-07-01

    We used optogenetic techniques in spinal cord and dorsal root ganglion (DRG) neuron studies. This study investigated changes in channelrhodopsin-2 (ChR2) expression in the spinal cord and DRG neurons using optogenetic techniques. The results show the possibility of using optogenetics to treat neuropathic pain. Previous studies have shown that activated ChR2 induces an increase in DRG neuron action potential. Western blot analysis was used to measure ChR2 protein levels in the spinal cord and DRG neurons or rats intrathecally injected with ChR2 lentivirus. Electrophysiology recording was used to detect differences in action potential levels in the spinal cord and calcium channel currents in the DRG neurons. Our studies showed that ChR2 expression increased the action potential in the spinal cord and increased calcium channel currents in DRG neurons. We successfully expressed the ChR2 protein in the spinal cord and DRG neurons. We also found that ChR2 increased the action potential in the spinal cord and activated the calcium channel in DRG neurons. These findings support the research possibilities of using optogenetic studies to improve treatment for neuropathic pain. N/A.

  10. Heterogeneous responses of dorsal root ganglion neurons in neuropathies induced by peripheral nerve trauma and the antiretroviral drug stavudine

    PubMed Central

    Boateng, EK; Novejarque, A; Pheby, T; Rice, ASC; Huang, W

    2015-01-01

    Background Heterogeneity is increasingly recognized in clinical presentation of neuropathic pain (NP), but less often recognized in animal models. Neurochemical dysregulation in rodent dorsal root ganglia (DRG) is associated with peripheral nerve trauma, but poorly studied in non-traumatic NP conditions. Methods This study aimed to investigate the temporal expressions of activating transcription factor-3 (ATF-3), growth-associated protein-43 (GAP-43), neuropeptide Y (NPY) and galanin in traumatic and non-traumatic rat models of neuropathies associated with NP. Expressions of these markers were examined in the DRG at different time points following tibial nerve transection (TNT) injury and antiretroviral drug stavudine (d4T) administration using immunohistochemistry. The development of sensory gain following these insults was assessed by measuring limb withdrawal to a punctate mechanical stimulus. Results Both TNT-injured and d4T-treated rats developed hindpaw mechanical hypersensitivity. Robust expressions of ATF-3, GAP-43, NPY and galanin in both small- and large-sized L5 DRG neurons were observed in the DRG from TNT-injured rats. In contrast, d4T-treated rats did not exhibit any significant neurochemical changes in the DRG. Conclusions Taken together, the results suggest that ATF-3, GAP-43, NPY and galanin are likely indicators of nerve trauma-associated processes and not generic markers for NP. These experiments also demonstrate distinct expression patterns of neurochemical markers in the DRG and emphasize the mechanistic difference between nerve trauma and antiretroviral drug-associated NP. PMID:25070481

  11. Effect of artemisinin on neuropathic pain mediated by P2X4 receptor in dorsal root ganglia.

    PubMed

    Ying, Mofeng; Liu, Hui; Zhang, Tengling; Jiang, Chenxu; Gong, Yingxin; Wu, Bing; Zou, Lifang; Yi, Zhihua; Rao, Shenqiang; Li, Guilin; Zhang, Chunping; Jia, Tianyu; Zhao, Shanhong; Yuan, Huilong; Shi, Liran; Li, Lin; Liang, Shangdong; Liu, Shuangmei

    2017-09-01

    Neuropathic pain is a type of chronic pain caused by nervous system damage and dysfunction. The pathogenesis of chronic pain is complicated, and there are no effective therapies for neuropathic pain. Studies show that the P2X4 receptor expressed in the satellite glial cells (SGCs) of dorsal root ganglia (DRG) is related to neuropathic pain. Artemisinin is a monomeric component extracted from traditional Chinese medicine and has a variety of important pharmacological effects and potential applications. This study observed the effect of artemisinin on neuropathic pain and delineated its possible mechanism. The chronic constriction injury (CCI) rat model was used in this study. The results demonstrated that artemisinin relieved pain behaviors in the CCI rats, inhibited the expression of P2X4 receptor in the DRG, and decreased the ATP-activated currents in HEK293 cells transfected with P2X4 plasmid. Dual-labeling immunofluorescence showed that the coexpression of P2X4 receptor and glial fibrillary acidic protein (GFAP) in the DRG of CCI rats was increased compared to control rats. After CCI rats were treated with artemisinin, the coexpression of P2X4 receptor and GFAP in the DRG was significantly decreased compared to the CCI group. This finding suggested that artemisinin could inhibit the nociceptive transmission mediated by P2X4 receptor in the DRG SGCs and thus relieve pain behaviors in the CCI rats. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. An ensemble of regulatory elements controls Runx3 spatiotemporal expression in subsets of dorsal root ganglia proprioceptive neurons.

    PubMed

    Appel, Elena; Weissmann, Sarit; Salzberg, Yehuda; Orlovsky, Kira; Negreanu, Varda; Tsoory, Michael; Raanan, Calanit; Feldmesser, Ester; Bernstein, Yael; Wolstein, Orit; Levanon, Ditsa; Groner, Yoram

    2016-12-01

    The Runx3 transcription factor is essential for development and diversification of the dorsal root ganglia (DRGs) TrkC sensory neurons. In Runx3-deficient mice, developing TrkC neurons fail to extend central and peripheral afferents, leading to cell death and disruption of the stretch reflex circuit, resulting in severe limb ataxia. Despite its central role, the mechanisms underlying the spatiotemporal expression specificities of Runx3 in TrkC neurons were largely unknown. Here we first defined the genomic transcription unit encompassing regulatory elements (REs) that mediate the tissue-specific expression of Runx3. Using transgenic mice expressing BAC reporters spanning the Runx3 locus, we discovered three REs-dubbed R1, R2, and R3-that cross-talk with promoter-2 (P2) to drive TrkC neuron-specific Runx3 transcription. Deletion of single or multiple elements either in the BAC transgenics or by CRISPR/Cas9-mediated endogenous ablation established the REs' ability to promote and/or repress Runx3 expression in developing sensory neurons. Our analysis reveals that an intricate combinatorial interplay among the three REs governs Runx3 expression in distinct subtypes of TrkC neurons while concomitantly extinguishing its expression in non-TrkC neurons. These findings provide insights into the mechanism regulating cell type-specific expression and subtype diversification of TrkC neurons in developing DRGs.

  13. Surgical extraction of human dorsal root ganglia from organ donors and preparation of primary sensory neuron cultures

    PubMed Central

    Valtcheva, Manouela V.; Copits, Bryan A.; Davidson, Steve; Sheahan, Tayler D.; Pullen, Melanie Y.; McCall, Jordan G.; Dikranian, Krikor; Gereau, Robert W.

    2016-01-01

    Primary cultures of rodent sensory neurons are widely used to investigate the cellular and molecular mechanisms involved in pain, itch, nerve injury, and regeneration. However, translation of these preclinical findings may be greatly improved by direct validation in human tissues. We have developed an approach to extract and culture human sensory neurons in collaboration with a local organ procurement organization. Here we describe the surgical procedure for extraction of human dorsal root ganglia (hDRG) and the necessary modifications to existing culture techniques to prepare viable adult human sensory neurons for functional studies. Dissociated sensory neurons can be maintained in culture for >10 days, and are amenable to electrophysiological recording, calcium imaging, and viral gene transfer. The entire process of extraction and culturing can be completed in less than 7 hours, and can be performed by trained graduate students. This approach can be applied at any institution with access to organ donors consenting to tissue donation for research and provides an invaluable resource for improving translational research. PMID:27606776

  14. The role of GDNF family ligand signalling in the differentiation of sympathetic and dorsal root ganglion neurons

    PubMed Central

    2008-01-01

    The diversity of neurons in sympathetic ganglia and dorsal root ganglia (DRG) provides intriguing systems for the analysis of neuronal differentiation. Cell surface receptors for the GDNF family ligands (GFLs) glial cell-line-derived neurotrophic factor (GDNF), neurturin and artemin, are expressed in subpopulations of these neurons prompting the question regarding their involvement in neuronal subtype specification. Mutational analysis in mice has demonstrated the requirement for GFL signalling during embryonic development of cholinergic sympathetic neurons as shown by the loss of expression from the cholinergic gene locus in ganglia from mice deficient for ret, the signal transducing subunit of the GFL receptor complex. Analysis in mutant animals and transgenic mice overexpressing GFLs demonstrates an effect on sensitivity to thermal and mechanical stimuli in DRG neurons correlating at least partially with the altered expression of transient receptor potential ion channels and acid-sensitive cation channels. Persistence of targeted cells in mutant ganglia suggests that the alterations are caused by differentiation effects and not by cell loss. Because of the massive effect of GFLs on neurite outgrowth, it remains to be determined whether GFL signalling acts directly on neuronal specification or indirectly via altered target innervation and access to other growth factors. The data show that GFL signalling is required for the specification of subpopulations of sensory and autonomic neurons. In order to comprehend this process fully, the role of individual GFLs, the transduction of the GFL signals, and the interplay of GFL signalling with other regulatory pathways need to be deciphered. PMID:18629541

  15. No overlap of sensitivity to capsaicin and expression of galanin in rat dorsal root ganglion neurons after axotomy.

    PubMed

    Wendland, Jens R; Schmidt, Klaus H; Koltzenburg, Martin; Petersen, Marlen

    2003-11-01

    The neuropeptide galanin is known to have an antinociceptive effect under neuropathic conditions. After axotomy, galanin is upregulated in sensory neurons, presumably in the capsaicin-sensitive ones. Here, the sensitivity to capsaicin and the expression of galanin were simultaneously examined by double-staining in individual, dissociated rat dorsal root ganglion neurons (1) after axotomy of the sciatic nerve for up to 14 days and (2) in culture for up to 4 days without prior nerve injury. Ten days after axotomy, the proportion of capsaicin-sensitive neurons had decreased by 36 percentage points (from 63% to 27%), whereas the proportion of galaninergic neurons had increased by 33 percentage points (from 3% to 36%). These changes were also observed in neurons kept in culture, where the regulation was attenuated by the addition of nerve growth factor (NGF) or glial cell line-derived neurotrophic factor (GDNF) to the medium. After axotomy, galaninergic neurons had a soma size-distribution profile similar to the capsaicin-sensitive neurons, but there was no colocalization of capsaicin sensitivity and galanin expression in individual neurons. In culture, some neurons showed colocalization after 30 h and 48 h, but not after 6 h or 96 h. We conclude that the upregulation of galanin in an individual neuron is preceded by downregulation of its capsaicin sensitivity both in NGF-dependent peptidergic and in GDNF-dependent non-peptidergic neurons, indicating a change in phenotype.

  16. Inhibition of acid-sensing ion channels by levo-tetrahydropalmatine in rat dorsal root ganglion neurons.

    PubMed

    Liu, Ting-Ting; Qu, Zu-Wei; Qiu, Chun-Yu; Qiu, Fang; Ren, Cuixia; Gan, Xiong; Peng, Fang; Hu, Wang-Ping

    2015-02-01

    Levo-tetrahydropalmatine (l-THP), a main bioactive Chinese herbal constituent from the genera Stephania and Corydalis, has been in use in clinical practice for years in China as a traditional analgesic agent. However, the mechanism underlying the analgesic action of l-THP is poorly understood. This study shows that l-THP can exert an inhibitory effect on the functional activity of native acid-sensing ion channels (ASICs), which are believed to mediate pain caused by extracellular acidification. l-THP dose dependently decreased the amplitude of proton-gated currents mediated by ASICs in rat dorsal root ganglion (DRG) neurons. l-THP shifted the proton concentration-response curve downward, with a decrease of 40.93% ± 8.45% in the maximum current response to protons, with no significant change in the pH0.5 value. Moreover, l-THP can alter the membrane excitability of rat DRG neurons to acid stimuli. It significantly decreased the number of action potentials and the amplitude of the depolarization induced by an extracellular pH drop. Finally, peripherally administered l-THP inhibited the nociceptive response to intraplantar injection of acetic acid in rats. These results indicate that l-THP can inhibit the functional activity of ASICs in dissociated primary sensory neurons and relieve acidosis-evoked pain in vivo, which for the first time provides a novel peripheral mechanism underlying the analgesic action of l-THP.

  17. Evaluation of poly(3,4-ethylenedioxythiophene)/carbon nanotube neural electrode coatings for stimulation in the dorsal root ganglion

    PubMed Central

    Kolarcik, Christi L.; Catt, Kasey; Rost, Erika; Albrecht, Ingrid N.; Bourbeau, Dennis; Du, Zhanhong; Kozai, Takashi D.Y.; Luo, Xiliang; Weber, Douglas J.; Cui, X. Tracy

    2015-01-01

    Objective The dorsal root ganglion (DRG) is an attractive target for implanting neural electrode arrays that restore sensory function or provide therapy via stimulation. However, penetrating microelectrodes designed for these applications are small and deliver low currents. For long-term performance of microstimulation devices, novel coating materials are needed in part to decrease impedance values at the electrode-tissue interface and to increase charge storage capacity. Approach Conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and multiwall carbon nanotubes (CNTs) were coated on the electrode surface and doped with the anti-inflammatory drug, dexamethasone. Electrode characteristics and the tissue reaction around neural electrodes as the result of stimulation, coating and drug release were characterized. Hematoxylin and eosin staining along with antibodies recognizing Iba1 (microglia/macrophages), NF200 (neuronal axons), NeuN (neurons), vimentin (fibroblasts), caspase-3 (cell death) and L1 (neural cell adhesion molecule) were used. Quantitative image analyses were performed using MATLAB. Main Results Our results indicate that coated microelectrodes have lower in vitro and in vivo impedance values. Significantly less neuronal death/damage was observed with coated electrodes as compared to non-coated controls. The inflammatory response with the PEDOT/CNT-coated electrodes was also reduced. Significance This study is the first to report on the utility of these coatings in stimulation applications. Our results indicate PEDOT/CNT coatings may be valuable additions to implantable electrodes used as therapeutic modalities. PMID:25485675

  18. Coculture of dorsal root ganglion neurons and differentiated human corneal stromal stem cells on silk-based scaffolds.

    PubMed

    Wang, Siran; Ghezzi, Chiara E; White, James D; Kaplan, David L

    2015-10-01

    Corneal tissue displays the highest peripheral nerve density in the human body. Engineering of biomaterials to promote interactions between neurons and corneal tissue could provide tissue models for nerve/cornea development, platforms for drug screening, as well as innovative opportunities to regenerate cornea tissue. The focus of this study was to develop a coculture system for differentiated human corneal stromal stem cells (dhCSSCs) and dorsal root ganglion neurons (DRG) to mimic the human cornea tissue interactions. Axon extension, connectivity, and neuron cell viability were studied. DRG neurons developed longer axons when cocultured with dhCSSCs in comparison to neuron cultures alone. To assess the mechanism involved in the coculture response, nerve growth factors (NGF) secreted by dhCSSCs including NGF, brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), and neurotrophin-3 were characterized with greater focus on BDNF secretion. DhCSSCs also secreted collagen type I, an extracellular matrix molecule favorable for neuronal outgrowth. This coculture system provides a slowly degrading silk matrix to study neuronal responses in concert with hCSSCs related to innervation of corneal tissue with utility toward human corneal nerve regeneration and associated diseases. © 2015 Wiley Periodicals, Inc.

  19. Overexpression of suppressor of cytokine signaling 3 in dorsal root ganglion attenuates cancer-induced pain in rats

    PubMed Central

    Wei, Jinrong; Li, Meng; Wang, Dieyu; Zhu, Hongyan; Kong, Xiangpeng; Wang, Shusheng; Zhou, You-Lang; Ju, Zhong; Jiang, Guo-Qin

    2017-01-01

    Background Cancer-induced pain (CIP) is one of the most severe types of chronic pain with which clinical treatment remains challenging and the involved mechanisms are largely unknown. Suppressor of cytokine signaling 3 (SOCS3) is an important intracellular protein and provides a classical negative feedback loop, thus involving in a wide variety of processes including inflammation and nociception. However, the role of SOCS3 pathway in CIP is poorly understood. The present study was designed to investigate the role of SOCS3 in dorsal root ganglion (DRG) in the development of CIP. Method CIP was established by injection of Walker 256 mammary gland tumor cells into the rat tibia canal. Whole-cell patch clamping and Western blotting were performed. Results Following the development of bone cancer, SOCS3 expression was significantly downregulated in rat DRGs at L2–L5 segments. Overexpression of SOCS3, using lentiviral-mediated production of SOCS3 at spinal cord level, drastically attenuated mechanical allodynia and body weight-bearing difference, but not thermal hyperalgesia in bone cancer rats. In addition, overexpression of SOCS3 reversed the hyperexcitability of DRG neurons innervating the tibia, and reduced abnormal expression of toll-like receptors 4 in the DRGs. Conclusions These results suggest that SOCS3 might be a key molecular involved in the development of complicated cancer pain and that overexpression of SOCS3 might be an important strategy for treatment for mechanical allodynia associated with bone cancer. PMID:28326931

  20. SL 75 102 as a gama-aminobutyric acid agonist: experiments on dorsal root ganglion neurones in vitro.

    PubMed Central

    Desarmenien, M.; Feltz, P.; Headley, P. M.; Santangelo, F.

    1981-01-01

    1 In anticipation that centrally active gamma-aminobutyric acid (GABA)-mimetic drugs may be clinically useful, derivatives of GABA with an imine link (Schiff base) to a lipophilic carrier have recently been prepared. The present paper concerns the actions of [alpha(4-chlorophenyl)5-fluoro, 2-hydroxy benzilidene-amino]-4-butanoate Na+, SL 75 102. 2 To test one aspect of the GABA-mimetic properties of SL 75 102, this compound was compared with GABA for activity on intracellularly-recorded neurones in rat dorsal root ganglia in vitro. On these neurones GABA, administered either by microiontophoresis or direct into the superfusion medium, causes a depolarization, due to an increased chloride conductance, followed by a period of desensitization. 3 The actions of Sl 75 102 were in nearly all respects identical to those of GABA; parameters examined were the effects on membrane potential and input conductance, desensitization, dose-response characteristics and sensitivity to the GABA antagonists, bicuculline and picrotoxin. 4 SL 75 102 was less potent than GABA (mean relative potency 0.03:1). 5 SL 75 102 therefore appears to be a weak agonist at GABA receptors of these neurones. PMID:7214101

  1. Expression of tyrosine kinase receptors in cultured dorsal root ganglion neurons in the presence of monosialoganglioside and skeletal muscle cells.

    PubMed

    Li, Hao; Zhang, Weiwei; Liu, Guixiang; Li, Jianmin; Liu, Huaxiang; Li, Zhenzhong

    2012-10-01

    The neurotrophic factor-like activity of monosialoganglioside (GM1) has been shown to activate tyrosine kinase receptors (Trk). Targets of neuronal innervation play a vital role in regulating the survival and differentiation of innervating neurotrophin-responsive neurons. Both GM1 and target skeletal muscle (SKM) cells are essential for the maintenance of the function of neurons. However, much less is known about the effects of GM1 or/and target SKM cells on the expression of Trk receptors in dorsal root ganglion (DRG) neurons. Here we have tested what extent to the expression of TrkA, TrkB, and TrkC receptors in primary cultured of DRG neurons in absence or presence of GM1 or/and SKM cells. In this experiment, we found that: (1) GM1 promoted expression of TrkA and TrkB but not TrkC in primary cultured DRG neurons; (2) target SKM cells promoted expression of TrkC but not TrkA and TrkB in neuromuscular cocultures without GM1 treatment; and (3) GM1 and target SKM cells had additional effects on expression of these three Trk receptors. The results of the present study offered new clues for a better understanding of the association of GM1 and target SKM on the expression of Trk receptors.

  2. Caspase-2 and microRNA34a/c regulate lidocaine-induced dorsal root ganglia apoptosis in vitro.

    PubMed

    Li, Yandong; Jia, Zhi; Zhang, Laizhu; Wang, Jianguo; Yin, Guangming

    2015-11-15

    Epidural administration of lidocaine may cause neurotoxicity in spinal cord dorsal root ganglia neurons (DRGNs). In this study, we explored the underling mechanisms of apoptotic pathways of lidocaine-induced apoptosis in DRGNs. Neonatal rat DRGNs were treated with lidocaine to induced apoptosis in vitro. Western blot showed caspase- (casp-) 2/3/9 proteins were all upregulated by lidocaine in DRGNs. However, inhibition of casp-2 protected lidocaine-induced apoptosis in DRGNs, whereas Casp3/9 inhibition did not. The possible upstream epigenetic regulators of casp-2, microRNA-34 (miR-34) family, including miR-34a/b/c, were evaluated by dual-luciferase reporter assay and qRT-PCR. We found miR-34a/c, but not miR-34b, were down-regulated in lidocaine-induced DRGN apoptosis. Subsequent upregulation of miR-34 family showed miR-34a/c were able to inhibit casp-2 and protect lidocaine-induced apoptosis in DRGNs, whereas miR-34b did not. Thus, out study shows that casp-2, in association with miR-34a/c was actively involved in lidocaine-induced apoptosis in DRGNs. Inhibiting casp-2 or upregulating miR-34a/c may provide novel meanings to protect local anesthetic-induced neurotoxicity. Copyright © 2015. Published by Elsevier B.V.

  3. MYCBP2 Is a Guanosine Exchange Factor for Ran Protein and Determines Its Localization in Neurons of Dorsal Root Ganglia*

    PubMed Central

    Dörr, Angela; Pierre, Sandra; Zhang, Dong D.; Henke, Marina; Holland, Sabrina; Scholich, Klaus

    2015-01-01

    The small GTPase Ran coordinates retrograde axonal transport in neurons, spindle assembly during mitosis, and the nucleo-cytoplasmic transport of mRNA. Its localization is tightly regulated by the GTPase-activating protein RanGAP1 and the nuclear guanosine exchange factor (GEF) RCC1. We show that loss of the neuronal E3 ubiquitin ligase MYCBP2 caused the up-regulation of Ran and RanGAP1 in dorsal root ganglia (DRG) under basal conditions and during inflammatory hyperalgesia. SUMOylated RanGAP1 physically interacted with MYCBP2 and inhibited its E3 ubiquitin ligase activity. Stimulation of neurons induced a RanGAP1-dependent translocation of MYCBP2 to the nucleus. In the nucleus of DRG neurons MYCBP2 co-localized with Ran and facilitated through its RCC1-like domain the GDP/GTP exchange of Ran. In accordance with the necessity of a GEF to promote GTP-binding and nuclear export of Ran, the nuclear localization of Ran was strongly increased in MYCBP2-deficient DRGs. The finding that other GEFs for Ran besides RCC1 exist gives new insights in the complexity of the regulation of the Ran signaling pathway. PMID:26304119

  4. Ca(2+) influx mediates the TRPV4-NO pathway in neuropathic hyperalgesia following chronic compression of the dorsal root ganglion.

    PubMed

    Wang, Jie; Wang, Xiao-Wei; Zhang, Yang; Yin, Cui-Ping; Yue, Shou-Wei

    2015-02-19

    Chronic compression of the dorsal root ganglion (DRG) (CCD) in rats is a typical model of neuropathic pain. TRPV4 contributed to mechanical allodynia induced by the CCD model. Our previous study demonstrated that TRPV4 enhances neuropathic hyperalgesia through a NO-cGMP-PKG cascade. However, the underlying mechanism(s) is still largely unknown. Therefore, the aim of the present study was to test whether TRPV4-mediated Ca(2+) influx is involved in the TRPV4-NO pathway. Regulation of intracellular calcium concentration by intrathecal injection of TRPV4-targeted siRNA significantly decreased the behavioural hyperalgesia, NF-κB activity, and NO content in CCD rats. Intraperitoneal (i.p.) injection of mibefradil significantly induced dose-dependent increases in the paw withdrawal latency (PWL) and mechanical withdrawal thresholds (MWT), as well as decreases in NF-κB activity and NO content in DRG of CCD rats. Moreover, pre-treatment with 4α-PDD attenuated the suppressive effects of mibefradil on CCD-induced neuropathic hyperalgesia, NF-κB activity, and NO production. The data showed that TRPV4-mediated Ca(2+) influx might be engaged in the TRPV4-NO pathway in neuropathic hyperalgesia in the CCD model. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  5. The effect of NR2B subunit palmitoylation at the spinal level after chronic dorsal root ganglia compression in rats.

    PubMed

    Xia, Tianjiao; Cui, Yin; Shi, Han; Ma, Zhengliang; Gu, Xiaoping

    2014-11-01

    The NR2B subunit (N-methyl-D-aspartate receptor 2B subunit) regulates the source of pain, and it participates in the formation of central sensitization. Palmitoylation was shown to be involved in the regulation of N-methyl-D-aspartate receptor internalization. In the present study, we investigated the effects of NR2B subunit palmitoylation in a chronic dorsal root ganglia compression (CCD) rat model. Paw mechanical withdrawal threshold and paw withdrawal thermal latency were used to assess mechanical allodynia and thermal hyperalgesia after a CCD operation and an intrathecal injection of the inhibitor of palmitoylation (2-bromopalmitate [2-BP]). The acyl-biotinyl exchange method, Western blotting, and coimmunoprecipitation were used to investigate the effects of pain processing and the expression of levels of NR2B palmitoylation and phosphorylation at the spinal level. CCD rats had long-lasting thermal hyperalgesia and mechanical allodynia, leading to upregulation of the level of NR2B palmitoylation and phosphorylation at the spinal level. An intrathecal treatment with 2-BP on day 14 after CCD surgery markedly improved pain behaviors and downregulated the expression of NR2B palmitoylation and phosphorylation. These data suggest that upregulated NR2B palmitoylation in CCD-induced neuropathic pain and intrathecal injection of 2-BP could reduce pain behaviors and NR2B phosphorylation. Our findings indicate that spinal NR2B palmitoylation is an important component of CCD-induced neuropathic pain, and it might be a potential target for chronic pain therapy.

  6. Aquaporin-1 Tunes Pain Perception by Interaction with Nav1.8 Na+ Channels in Dorsal Root Ganglion Neurons*

    PubMed Central

    Zhang, Hua; Verkman, A. S.

    2010-01-01

    Aquaporin-1 (AQP1) water channels are expressed in the plasma membrane of dorsal root ganglion (DRG) neurons. We found reduced osmotic water permeability in freshly isolated DRG neurons from AQP1−/− versus AQP1+/+ mice. Behavioral studies showed greatly reduced thermal inflammatory pain perception in AQP1−/− mice evoked by bradykinin, prostaglandin E2, and capsaicin as well as reduced cold pain perception. Patch clamp of freshly isolated DRG neurons showed reduced action potential firing in response to current injections. Single action potentials after pulse current injections showed reduced maximum inward current, suggesting impaired Nav1.8 Na+ function. Whole-cell Nav1.8 Na+ currents in Nav1.8-expressing ND7-23 cells showed slowed frequency-dependent inactivation after AQP1 transfection. Immunoprecipitation studies showed AQP1- Nav1.8 Na+ interaction, which was verified in live cells by single-particle tracking of quantum dot-labeled AQP1. Our results implicate the involvement of AQP1 in DRG neurons for the perception of inflammatory thermal pain and cold pain, whose molecular basis is accounted for, in part, by reduced Nav1.8-dependent membrane Na+ current. AQP1 is, thus, a novel target for pain management. PMID:20018876

  7. Neuron-glial communication mediated by TNF-α and glial activation in dorsal root ganglia in visceral inflammatory hypersensitivity.

    PubMed

    Song, Dan-dan; Li, Yong; Tang, Dong; Huang, Li-ya; Yuan, Yao-zong

    2014-05-01

    Communication between neurons and glia in the dorsal root ganglia (DRG) and the central nervous system is critical for nociception. Both glial activation and proinflammatory cytokine induction underlie this communication. We investigated whether satellite glial cell (SGC) and tumor necrosis factor-α (TNF-α) activation in DRG participates in a 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rat model of visceral hyperalgesia. In TNBS-treated rats, TNF-α expression increased in DRG and was colocalized to SGCs enveloping a given neuron. These SGCs were activated as visualized under electron microscopy: they had more elongated processes projecting into the connective tissue space and more gap junctions. When nerves attached to DRG (L6-S1) were stimulated with a series of electrical stimulations, TNF-α were released from DRG in TNBS-treated animals compared with controls. Using a current clamp, we noted that exogenous TNF-α (2.5 ng/ml) increased DRG neuron activity, and visceral pain behavioral responses were reversed by intrathecal administration of anti-TNF-α (10 μg·kg(-1)·day(-1)). Based on our findings, TNF-α and SGC activation in neuron-glial communication are critical in inflammatory visceral hyperalgesia.

  8. Modulation of nano-selenium on tetrodotoxin-sensitive voltage-gated sodium currents in rat dorsal root ganglion neurons.

    PubMed

    Yuan, Huijun; Lan, Tonghan; Lin, Jiarui

    2005-01-01

    Nano-Selenium, a novel Nano technology production, was demonstrated to be useful in medical and scientific researches. Here, we investigated the effects of Nano-Selenium on tetrodotoxin-sensitive (TTX-S) voltage-dependent Na+channels in isolated rat dorsal root ganglion neurons, using whole-cell patch-clamp method. Nano-Selenium irreversibly decreased TTX-S Na+current (INa) in a concentration-dependent manner and shifted the maximum of the current/voltage relationship from -67mV to -52mV, without modifying the threshold potential of the current. Nano-Selenium shifted the steady-state activation and inactivation curves to the left. In the contrast of Na2SeO3, the inhibition effect of 1nM Nano-Se was much stronger. The cell treated with 1nM Na2SeO3firstly, still respond to futher addition of 1nM Nano-Selenium. These results prove Nano-Selenium to be a novel antiagonist, acted within the channel pore, not on or near the exterior surface of the channel protein where it would experience the membrane electric field, which possesses a distinct binding site from Na2SeO3.

  9. Effects of postnatal anti-NGF on the development of CGRP-IR neurons in the dorsal root ganglion.

    PubMed

    Tonra, J R; Mendell, L M

    1998-03-23

    Experiments were undertaken to examine anatomical correlates of physiological effects of rabbit sera raised against nerve growth factor (anti-NGF) on nociceptive afferents. This antiserum has been shown to deplete the population of A-delta high threshold mechanoreceptors and to reduce neurogenic vasodilatation. Because numerous studies implicate calcitonin gene related peptide (CGRP)-containing sensory neurons in these effects, immunocytochemical and anatomical techniques were used to examine the normal development of CGRP-immunoreactive (-IR) neurons in the dorsal root ganglion (DRG) of rats from 13 days to 19 weeks of age, and to compare this to the development in rats treated neonatally (postnatal days 2-14) with anti-NGF. In controls the rate of increase in the mean diameter of CGRP-IR cells was substantially greater between 13 days and 5 weeks of age than it was between 5 weeks and 19 weeks, in contrast to CGRP-negative neurons whose rate of growth remained relatively constant. Anti-NGF had no significant effect on growth rate, but rats treated with anti-NGF exhibited a reduced proportion of CGRP-IR neurons at 5 weeks. This deficit was reversed by 19 weeks unlike the physiological changes. These results indicate independent regulation of CGRP expression and nociceptor physiology by NGF.

  10. 3D-Printed pHEMA Materials for Topographical and Biochemical Modulation of Dorsal Root Ganglion Cell Response.

    PubMed

    Badea, Adina; McCracken, Joselle M; Tillmaand, Emily G; Kandel, Mikhail E; Oraham, Aaron W; Mevis, Molly B; Rubakhin, Stanislav S; Popescu, Gabriel; Sweedler, Jonathan V; Nuzzo, Ralph G

    2017-09-13

    Understanding and controlling the interactions occurring between cells and engineered materials are central challenges toward progress in the development of biomedical devices. In this work, we describe materials for direct ink writing (DIW), an extrusion-based type of 3D printing, that embed a custom synthetic protein (RGD-PDL) within the microfilaments of 3D-hydrogel scaffolds to modify these interactions and differentially direct tissue-level organization of complex cell populations in vitro. The RGD-PDL is synthesized by modifying poly-d-lysine (PDL) to varying extents with peptides containing the integrin-binding motif Arg-Gly-Asp (RGD). Compositional gradients of the RGD-PDL presented by both patterned and thin-film poly(2-hydroxyethyl) methacrylate (pHEMA) substrates allow the patterning of cell-growth compliance in a grayscale form. The surface chemistry-dependent guidance of cell growth on the RGD-PDL-modified pHEMA materials is demonstrated using a model NIH-3T3 fibroblast cell line. The formation of a more complex cellular system-organotypic primary murine dorsal root ganglion (DRG)-in culture is also achieved on these scaffolds, where distinctive forms of cell growth and migration guidance are seen depending on their RGD-PDL content and topography. This experimental platform for the study of physicochemical factors on the formation and the reorganization of organotypic cultures offers useful capabilities for studies in tissue engineering, regenerative medicine, and diagnostics.

  11. Mitochondrial Respiratory Chain Dysfunction in Dorsal Root Ganglia of Streptozotocin-Induced Diabetic Rats and Its Correction by Insulin Treatment

    PubMed Central

    Chowdhury, Subir K. Roy; Zherebitskaya, Elena; Smith, Darrell R.; Akude, Eli; Chattopadhyay, Sharmila; Jolivalt, Corinne G.; Calcutt, Nigel A.; Fernyhough, Paul

    2010-01-01

    OBJECTIVE Impairments in mitochondrial physiology may play a role in diabetic sensory neuropathy. We tested the hypothesis that mitochondrial dysfunction in sensory neurons is due to abnormal mitochondrial respiratory function. RESEARCH DESIGN AND METHODS Rates of oxygen consumption were measured in mitochondria from dorsal root ganglia (DRG) of 12- to- 22-week streptozotocin (STZ)-induced diabetic rats, diabetic rats treated with insulin, and age-matched controls. Activities and expression of components of mitochondrial complexes and reactive oxygen species (ROS) were analyzed. RESULTS Rates of coupled respiration with pyruvate + malate (P + M) and with ascorbate + TMPD (Asc + TMPD) in DRG were unchanged after 12 weeks of diabetes. By 22 weeks of diabetes, respiration with P + M was significantly decreased by 31–44% and with Asc + TMPD by 29–39% compared with control. Attenuated mitochondrial respiratory activity of STZ-diabetic rats was significantly improved by insulin that did not correct other indices of diabetes. Activities of mitochondrial complexes I and IV and the Krebs cycle enzyme, citrate synthase, were decreased in mitochondria from DRG of 22-week STZ-diabetic rats compared with control. ROS levels in perikarya of DRG neurons were not altered by diabetes, but ROS generation from mitochondria treated with antimycin A was diminished compared with control. Reduced mitochondrial respiratory function was associated with downregulation of expression of mitochondrial proteins. CONCLUSIONS Mitochondrial dysfunction in sensory neurons from type 1 diabetic rats is associated with impaired rates of respiratory activity and occurs without a significant rise in perikaryal ROS. PMID:20103706

  12. The effect of sinomenine in diabetic neuropathic pain mediated by the P2X3 receptor in dorsal root ganglia.

    PubMed

    Rao, Shenqiang; Liu, Shuangmei; Zou, Lifang; Jia, Tianyu; Zhao, Shanhong; Wu, Bing; Yi, Zhihua; Wang, Shouyu; Xue, Yun; Gao, Yun; Xu, Changshui; Li, Guilin; Xu, Hong; Zhang, Chunping; Liang, Shangdong

    2017-01-04

    Type 2 diabetes mellitus (T2DM) accounts for more than 90% of all cases of diabetes mellitus (DM). Diabetic neuropathic pain (DNP) is a common complication of T2DM. Sinomenine is a natural bioactive component extracted from the Sinomenium acutum and has anti-inflammatory effects. The aim of our study was to investigate the effects of sinomenine on DNP mediated by the P2X3 receptor in dorsal root ganglia (DRG). The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) in T2DM rats were lower than those of control rats. MWT and TWL in T2DM rats treated with sinomenine were higher compared with those in T2DM rats. The expression levels of the P2X3 protein and mRNA in T2DM rat DRG were higher compared with those of the control, while those in T2DM rats treated with sinomenine were significantly lower compared with those of the T2DM rats. Sinomenine significantly inhibited P2X3 agonist ATP-activated currents in HEK293 cells transfected with the P2X3 receptor. Sinomenine decreased the phosphorylation and activation of P38MAPK in T2DM DRG. Therefore, sinomenine treatment may suppress the up-regulated expression and activation of the P2X3 receptor and relieve the hyperalgesia potentiated by the activation of P38MAPK in T2DM rats.

  13. Monocyte Traffic, Dorsal Root Ganglion Histopathology, and Loss of Intraepidermal Nerve Fiber Density in SIV Peripheral Neuropathy

    PubMed Central

    Lakritz, Jessica R.; Bodair, Ayman; Shah, Neal; O'Donnell, Ryan; Polydefkis, Michael J.; Miller, Andrew D.; Burdo, Tricia H.

    2016-01-01

    HIV-associated sensory neuropathy remains the most common neurological complication of HIV infection and is characterized by dorsal root ganglion (DRG) inflammation and intraepidermal nerve fiber density (IENFD) loss. Chronic peripheral immune cell activation and accumulation may cause damage to the DRG, but has not been fully investigated yet. By using an SIV-infected, CD8-lymphocyte–depleted rhesus macaque model, we defined immune cells surrounding DRG neurons and their role in DRG pathology, measured cell traffic from the bone marrow to the DRGs using 5-bromo-2-deoxyuridine (BrdU) pulse, and serially measured IENFD. We found an increase in CD68+ and CD163+ macrophages in DRGs of SIV-infected animals. MAC387+ recently recruited monocytes/macrophages were increased, along with BrdU+ cells, in the DRGs of SIV-infected macaques. We demonstrated that 78.1% of all BrdU+ cells in DRGs were also MAC387+. The number of BrdU+ monocytes correlated with severe DRG histopathology, which included neuronophagia, neuronal loss, and Nageotte nodules. These data demonstrate that newly recruited MAC387+BrdU+ macrophages may play a significant role in DRG pathogenesis. IENFD decreased early (day 21), consistent with the development of sensory neuropathy in SIV-infected macaques. Decreased IENFD was associated with elevated BrdU+ cells in the DRG. These data suggest that increased recruitment of macrophages to DRG is associated with severe DRG histopathology and IENFD loss. PMID:25956030

  14. Modulation of Spinal GABAergic Inhibition and Mechanical Hypersensitivity following Chronic Compression of Dorsal Root Ganglion in the Rat

    PubMed Central

    Lee, Moon Chul; Nam, Taick Sang; Jung, Se Jung; Gwak, Young S.; Leem, Joong Woo

    2015-01-01

    Chronic compression of dorsal root ganglion (CCD) results in neuropathic pain. We investigated the role of spinal GABA in CCD-induced pain using rats with unilateral CCD. A stereological analysis revealed that the proportion of GABA-immunoreactive neurons to total neurons at L4/5 laminae I–III on the injured side decreased in the early phase of CCD (post-CCD week 1) and then returned to the sham-control level in the late phase (post-CCD week 18). In the early phase, the rats showed an increase in both mechanical sensitivity of the hind paw and spinal WDR neuronal excitability on the injured side, and such increase was suppressed by spinally applied muscimol (GABA-A agonist, 5 nmol) and baclofen (GABA-B agonist, 25 nmol), indicating the reduced spinal GABAergic inhibition involved. In the late phase, the CCD-induced increase in mechanical sensitivity and neuronal excitability returned to pre-CCD levels, and such recovered responses were enhanced by spinally applied bicuculline (GABA-A antagonist, 15 nmol) and CGP52432 (GABA-B antagonist, 15 nmol), indicating the regained spinal GABAergic inhibition involved. In conclusion, the alteration of spinal GABAergic inhibition following CCD and leading to a gradual reduction over time of CCD-induced mechanical hypersensitivity is most likely due to changes in GABA content in spinal GABA neurons. PMID:26451259

  15. Microsurgical procedures in the peripheral nerves and the dorsal root entry zone for the treatment of spasticity.

    PubMed

    Sindou, M; Keravel, Y

    1988-01-01

    When spasticity becomes severe and harmful, in spite of physical and medical therapy, neurosurgery can give functional improvement. This paper deals with the long term results of Selective Peripheral Neurotomies of the Tibial Nerve and Selective Posterior Rhizotomies in the Dorsal Root Entry Zone, in 123 patients with spastic disorders localized to the limbs. The micro-techniques and intra-operative electro-stimulation for identification of the nervous structures responsible for the spastic components, can give a substantial reduction of the harmful spasticity, without suppressing the useful muscle tone and impairing the residual motor and sensory functions. The results were effective, with a 1 to 13 year follow-up (5 on average), in 89% of 47 Selective Peripheral Neurotomies of the tibial nerve for spastic foot, in 92% of 53 Selective Posterior Rhizotomies for paraplegia and in 87% of 23 Selective Posterior Rhizotomies for hemiplegia. In the most severe situations ("comfort" indications), correction of the abnormal postures and relief of pain facilitated nursing and physiotherapy. Sometimes there was reappearance of some useful voluntary movements. In the less affected patients ("functional" indications), the suppression of the harmful spastic components made the persistant capacities more effective.

  16. An ensemble of regulatory elements controls Runx3 spatiotemporal expression in subsets of dorsal root ganglia proprioceptive neurons

    PubMed Central

    Appel, Elena; Weissmann, Sarit; Salzberg, Yehuda; Orlovsky, Kira; Negreanu, Varda; Tsoory, Michael; Raanan, Calanit; Feldmesser, Ester; Bernstein, Yael; Wolstein, Orit; Levanon, Ditsa; Groner, Yoram

    2016-01-01

    The Runx3 transcription factor is essential for development and diversification of the dorsal root ganglia (DRGs) TrkC sensory neurons. In Runx3-deficient mice, developing TrkC neurons fail to extend central and peripheral afferents, leading to cell death and disruption of the stretch reflex circuit, resulting in severe limb ataxia. Despite its central role, the mechanisms underlying the spatiotemporal expression specificities of Runx3 in TrkC neurons were largely unknown. Here we first defined the genomic transcription unit encompassing regulatory elements (REs) that mediate the tissue-specific expression of Runx3. Using transgenic mice expressing BAC reporters spanning the Runx3 locus, we discovered three REs—dubbed R1, R2, and R3—that cross-talk with promoter-2 (P2) to drive TrkC neuron-specific Runx3 transcription. Deletion of single or multiple elements either in the BAC transgenics or by CRISPR/Cas9-mediated endogenous ablation established the REs’ ability to promote and/or repress Runx3 expression in developing sensory neurons. Our analysis reveals that an intricate combinatorial interplay among the three REs governs Runx3 expression in distinct subtypes of TrkC neurons while concomitantly extinguishing its expression in non-TrkC neurons. These findings provide insights into the mechanism regulating cell type-specific expression and subtype diversification of TrkC neurons in developing DRGs. PMID:28007784

  17. Real-time control of hind limb functional electrical stimulation using feedback from dorsal root ganglia recordings

    PubMed Central

    Bruns, Tim M; Wagenaar, Joost B; Bauman, Matthew J; Gaunt, Robert A; Weber, Douglas J

    2013-01-01

    Objective Functional electrical stimulation (FES) approaches often utilize an open-loop controller to drive state transitions. The addition of sensory feedback may allow for closed-loop control that can respond effectively to perturbations and muscle fatigue. Approach We evaluated the use of natural sensory nerve signals obtained with penetrating microelectrode arrays in lumbar dorsal root ganglia (DRG) as real-time feedback for closed-loop control of FES-generated hind limb stepping in anesthetized cats. Main results Leg position feedback was obtained in near real-time at 50 ms intervals by decoding the firing rates of more than 120 DRG neurons recorded simultaneously. Over 5 m of effective linear distance was traversed during closed-loop stepping trials in each of two cats. The controller compensated effectively for perturbations in the stepping path when DRG sensory feedback was provided. The presence of stimulation artifacts and the quality of DRG unit sorting did not significantly affect the accuracy of leg position feedback obtained from the linear decoding model as long as at least 20 DRG units were included in the model. Significance This work demonstrates the feasibility and utility of closed-loop FES control based on natural neural sensors. Further work is needed to improve the controller and electrode technologies and to evaluate long-term viability. PMID:23503062

  18. Effects of (-)-gallocatechin-3-gallate on tetrodotoxin-resistant voltage-gated sodium channels in rat dorsal root ganglion neurons.

    PubMed

    Zhang, Yan; Jia, Yan-Yan; Guo, Jin-Lei; Liu, Pei-Qing; Jiang, Jian-Min

    2013-05-07

    The (-)-gallocatechin-3-gallate (GCG) concentration in some tea beverages can account for as much as 50% of the total catechins. It has been shown that catechins have analgesic properties. Voltage-gated sodium channels (Nav) mediate neuronal action potentials. Tetrodotoxin inhibits all Nav isoforms, but Nav1.8 and Nav1.9 are relatively tetrodotoxin-resistant compared to other isoforms and functionally linked to nociception. In this study, the effects of GCG on tetrodotoxin-resistant Na+ currents were investigated in rat primary cultures of dorsal root ganglion neurons via the whole-cell patch-clamp technique. We found that 1 μM GCG reduced the amplitudes of peak current density of tetrodotoxin-resistant Na+ currents significantly. Furthermore, the inhibition was accompanied by a depolarizing shift of the activation voltage and a hyperpolarizing shift of steady-state inactivation voltage. The percentage block of GCG (1 μM) on tetrodotoxin-resistant Na+ current was 45.1% ± 1.1% in 10 min. In addition, GCG did not produce frequency-dependent block of tetrodotoxin-resistant Na+ currents at stimulation frequencies of 1 Hz, 2 Hz and 5 Hz. On the basis of these findings, we propose that GCG may be a potential analgesic agent.

  19. Downregulation of ClC-3 in dorsal root ganglia neurons contributes to mechanical hypersensitivity following peripheral nerve injury.

    PubMed

    Pang, Rui-Ping; Xie, Man-Xiu; Yang, Jie; Shen, Kai-Feng; Chen, Xi; Su, Ying-Xue; Yang, Chao; Tao, Jing; Liang, Si-Jia; Zhou, Jia-Guo; Zhu, He-Quan; Wei, Xu-Hong; Li, Yong-Yong; Qin, Zhi-Hai; Liu, Xian-Guo

    2016-11-01

    ClC-3 chloride channel/antiporter has been demonstrated to play an important role in synaptic transmission in central nervous system. However, its expression and function in sensory neurons is poorly understood. In present work, we found that ClC-3 is expressed at high levels in dorsal root ganglia (DRG). Co-immunofluorescent data showed that ClC-3 is mainly distributed in A- and C-type nociceptive neurons. ClC-3 expression in DRG is decreased in the spared nerve injury (SNI) model of neuropathic pain. Knockdown of local ClC-3 in DRG neurons with siRNA increased mechanical sensitivity in naïve rats, while overexpression of ClC-3 reversed the hypersensitivity to mechanical stimuli after peripheral nerve injury. In addition, genetic deletion of ClC-3 enhances mouse mechanical sensitivity but did not affect thermal and cold threshold. Restoration of ClC-3 expression in ClC-3 deficient mice reversed the mechanical sensitivity. Mechanistically, loss of ClC-3 enhanced mechanical sensitivity through increasing the excitability of DRG neurons. These data indicate that ClC-3 is an endogenous inhibitor of neuropathic pain development. Downregulation of ClC-3 by peripheral nerve injury is critical for mechanical hypersensitivity. Our findings suggest that ClC-3 is a novel therapeutic target for treating neuropathic pain.

  20. 7, 8, 3'-Trihydroxyflavone Promotes Neurite Outgrowth and Protects Against Bupivacaine-Induced Neurotoxicity in Mouse Dorsal Root Ganglion Neurons.

    PubMed

    Shi, Haohong; Luo, Xingjing

    2016-07-02

    BACKGROUND 7, 8, 3'-trihydroxyflavone (THF) is a novel pro-neuronal small molecule that acts as a TrkB agonist. In this study, we examined the effect of THF on promoting neuronal growth and protecting anesthetics-induced neurotoxicity in dorsal root ganglion (DRG) neurons in vitro. MATERIAL AND METHODS Neonatal mouse DRG neurons were cultured in vitro and treated with various concentrations of THF. The effect of THF on neuronal growth was investigated by neurite outgrowth assay and Western blot. In addition, the protective effects of THF on bupivacaine-induced neurotoxicity were investigated by apoptosis TUNEL assay, neurite outgrowth assay, and Western blot, respectively. RESULTS THF promoted neurite outgrowth of DRG neurons in dose-dependent manner, with an EC50 concentration of 67.4 nM. Western blot analysis showed THF activated TrkB signaling pathway by inducing TrkB phosphorylation. THF also rescued bupivacaine-induced neurotoxicity by reducing apoptosis and protecting neurite retraction in DRG neurons. Furthermore, the protection of THF in bupivacaine-injured neurotoxicity was directly associated with TrkB phosphorylation in a concentration-dependent manner in DRG neurons. CONCLUSIONS THF has pro-neuronal effect on DRG neurons by promoting neurite growth and protecting against bupivacaine-induced neurotoxicity, likely through TrkB activation.

  1. GTP-dependent run-up of Piezo2-type mechanically activated currents in rat dorsal root ganglion neurons.

    PubMed

    Jia, Zhanfeng; Ikeda, Ryo; Ling, Jennifer; Gu, Jianguo G

    2013-12-17

    Rapidly adapting mechanically activated channels (RA) are expressed in primary afferent neurons and identified as Piezo2 ion channels. We made whole-cell voltage-clamp recordings from cultured dorsal root ganglion (DRG) neurons to study RA channel regulation. RA currents showed gradual increases in current amplitude (current "run-up") after establishing whole-cell mode when 0.33 mM GTP or 0.33 mM GTPγS was included in the patch pipette internal solution. RA current run-up was also observed in HEK293 cells that heterologously expressed Piezo2 ion channels. No significant RA current run-up was observed in DRG neurons when GTP was omitted from the patch pipette internal solution, when GTP was replaced with 0.33 mM GDP, or when recordings were made under the perforated patch-clamp recording configuration. Our findings revealed a GTP-dependent up-regulation of the function of piezo2 ion channels in DRG neurons.

  2. GTP-dependent run-up of Piezo2-type mechanically activated currents in rat dorsal root ganglion neurons

    PubMed Central

    2013-01-01

    Rapidly adapting mechanically activated channels (RA) are expressed in primary afferent neurons and identified as Piezo2 ion channels. We made whole-cell voltage-clamp recordings from cultured dorsal root ganglion (DRG) neurons to study RA channel regulation. RA currents showed gradual increases in current amplitude (current “run-up”) after establishing whole-cell mode when 0.33 mM GTP or 0.33 mM GTPγS was included in the patch pipette internal solution. RA current run-up was also observed in HEK293 cells that heterologously expressed Piezo2 ion channels. No significant RA current run-up was observed in DRG neurons when GTP was omitted from the patch pipette internal solution, when GTP was replaced with 0.33 mM GDP, or when recordings were made under the perforated patch-clamp recording configuration. Our findings revealed a GTP-dependent up-regulation of the function of piezo2 ion channels in DRG neurons. PMID:24344923

  3. Role of dorsal root ganglion K2P1.1 in peripheral nerve injury-induced neuropathic pain

    PubMed Central

    Mao, Qingxiang; Yuan, Jingjing; Xiong, Ming; Wu, Shaogen; Chen, Liyong; Bekker, Alex; Yang, Tiande

    2017-01-01

    Peripheral nerve injury-caused hyperexcitability and abnormal ectopic discharges in the primary sensory neurons of dorsal root ganglion (DRG) play a key role in neuropathic pain development and maintenance. The two-pore domain background potassium (K2P) channels have been identified as key determinants of the resting membrane potential and neuronal excitability. However, whether K2P channels contribute to neuropathic pain is still elusive. We reported here that K2P1.1, the first identified mammalian K2P channel, was highly expressed in mouse DRG and distributed in small-, medium-, and large-sized DRG neurons. Unilateral lumbar (L) 4 spinal nerve ligation led to a significant and time-dependent reduction of K2P1.1 mRNA and protein in the ipsilateral L4 DRG, but not in the contralateral L4 or ipsilateral L3 DRG. Rescuing this reduction through microinjection of adeno-associated virus-DJ expressing full-length K2P1.1 mRNA into the ipsilateral L4 DRG blocked spinal nerve ligation-induced mechanical, thermal, and cold pain hypersensitivities during the development and maintenance periods. This DRG viral microinjection did not affect acute pain and locomotor function. Our findings suggest that K2P1.1 participates in neuropathic pain development and maintenance and may be a potential target in the management of this disorder. PMID:28326939

  4. Tang-Luo-Ning Improves Mitochondrial Antioxidase Activity in Dorsal Root Ganglia of Diabetic Rats: A Proteomics Study

    PubMed Central

    Gao, Yanbin; Gong, Yanbin; Zhou, Hui; Xie, Peifeng; Guan, Song; Yi, Wenming

    2017-01-01

    Tang-luo-ning (TLN) is a traditional Chinese herbal recipe for treating diabetic peripheral neuropathy (DPN). In this study, we investigated mitochondrial protein profiles in a diabetic rat model and explored the potential protective effect of TLN. Diabetic rats were established by injection of streptozocin (STZ) and divided into model, alpha lipoic acid (ALA), and TLN groups. Mitochondrial proteins were isolated from dorsal root ganglia and proteomic analysis was used to quantify the differentially expressed proteins. Tang-luo-ning mitigated STZ-induced diabetic symptoms and blood glucose level, including response time to cold or hot stimulation and nerve conductive velocity. As compared to the normal, there were 388 differentially expressed proteins in the TLN group, 445 in ALA group, and 451 in model group. As compared to the model group, there were 275 differential proteins in TLN group and 251 in ALA group. As compared to model group, mitochondrial complex III was significantly decreased, while glutathione peroxidase and peroxidase were increased in TLN group. When compared with ALA group, the mitochondrial complex III was increased, and mitochondrial complex IV was decreased in TLN group. Together, TLN should have a strong antioxidative activity, which appears to be modulated through regulation of respiratory complexes and antioxidases. PMID:28133612

  5. Evaluation of poly(3,4-ethylenedioxythiophene)/carbon nanotube neural electrode coatings for stimulation in the dorsal root ganglion

    NASA Astrophysics Data System (ADS)

    Kolarcik, Christi L.; Catt, Kasey; Rost, Erika; Albrecht, Ingrid N.; Bourbeau, Dennis; Du, Zhanhong; Kozai, Takashi D. Y.; Luo, Xiliang; Weber, Douglas J.; Cui, X. Tracy

    2015-02-01

    Objective. The dorsal root ganglion is an attractive target for implanting neural electrode arrays that restore sensory function or provide therapy via stimulation. However, penetrating microelectrodes designed for these applications are small and deliver low currents. For long-term performance of microstimulation devices, novel coating materials are needed in part to decrease impedance values at the electrode-tissue interface and to increase charge storage capacity. Approach. Conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and multi-wall carbon nanotubes (CNTs) were coated on the electrode surface and doped with the anti-inflammatory drug, dexamethasone. Electrode characteristics and the tissue reaction around neural electrodes as a result of stimulation, coating and drug release were characterized. Hematoxylin and eosin staining along with antibodies recognizing Iba1 (microglia/macrophages), NF200 (neuronal axons), NeuN (neurons), vimentin (fibroblasts), caspase-3 (cell death) and L1 (neural cell adhesion molecule) were used. Quantitative image analyses were performed using MATLAB. Main results. Our results indicate that coated microelectrodes have lower in vitro and in vivo impedance values. Significantly less neuronal death/damage was observed with coated electrodes as compared to non-coated controls. The inflammatory response with the PEDOT/CNT-coated electrodes was also reduced. Significance. This study is the first to report on the utility of these coatings in stimulation applications. Our results indicate PEDOT/CNT coatings may be valuable additions to implantable electrodes used as therapeutic modalities.

  6. Upregulation of EMMPRIN (OX47) in Rat Dorsal Root Ganglion Contributes to the Development of Mechanical Allodynia after Nerve Injury.

    PubMed

    Wang, Qun; Sun, Yanyuan; Ren, Yingna; Gao, Yandong; Tian, Li; Liu, Yang; Pu, Yanan; Gou, Xingchun; Chen, Yanke; Lu, Yan

    2015-01-01

    Matrix metalloproteinases (MMPs) are widely implicated in inflammation and tissue remodeling associated with various neurodegenerative diseases and play an important role in nociception and allodynia. Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) plays a key regulatory role for MMP activities. However, the role of EMMPRIN in the development of neuropathic pain is not clear. Western blotting, real-time quantitative RT-PCR (qRT-PCR), and immunofluorescence were performed to determine the changes of messenger RNA and protein of EMMPRIN/OX47 and their cellular localization in the rat dorsal root ganglion (DRG) after nerve injury. Paw withdrawal threshold test was examined to evaluate the pain behavior in spinal nerve ligation (SNL) model. The lentivirus containing OX47 shRNA was injected into the DRG one day before SNL. The expression level of both mRNA and protein of OX47 was markedly upregulated in ipsilateral DRG after SNL. OX47 was mainly expressed in the extracellular matrix of DRG. Administration of shRNA targeted against OX47 in vivo remarkably attenuated mechanical allodynia induced by SNL. In conclusion, peripheral nerve injury induced upregulation of OX47 in the extracellular matrix of DRG. RNA interference against OX47 significantly suppressed the expression of OX47 mRNA and the development of mechanical allodynia. The altered expression of OX47 may contribute to the development of neuropathic pain after nerve injury.

  7. Brain-derived neurotrophic factor expression in dorsal root ganglia of a lumbar spinal stenosis model in rats.

    PubMed

    Li, Qinliang; Liu, Yi; Chu, Zhaoming; Chen, Jinchuan; Dai, Fenglei; Zhu, Xiaorong; Hu, Ankang; Yun, Cai

    2013-12-01

    This study aimed to investigate the expression of brain-derived neurotrophic factor (BDNF) in dorsal root ganglia (DRG) of a rat model of lumbar spinal stenosis (LSS). Adult male rats were divided into the operation and sham operation groups. The operation group was comprised of the rat models of LSS. Walking distance and BDNF expression levels in DRG were measured in the two groups at different time points. The total BDNF protein levels and positive cell mean optical density (MOD) values in the operation group were significantly higher at each time point compared with that of the sham operation and preoperative control groups (P<0.05). The total BDNF protein levels and MOD values following sport in the operation group were significantly higher compared with those prior to sport (P<0.05). In the sham operation group, BDNF protein levels and MOD values before and after sport at each time point showed no significant differences than those of the operation group (P>0.05). Moreover, BDNF protein levels and MOD values in the operation group indicated a negative correlation with walking distance. The present study demonstrated that the expression of BDNF in rat models of LSS increased with time and was associated with a decrease in walking distance. BDNF was therefore important for the process of intermittent claudication caused by LSS.

  8. Infection by human varicella-zoster virus confers norepinephrine sensitivity to sensory neurons from rat dorsal root ganglia.

    PubMed

    Kress, M; Fickenscher, H

    2001-04-01

    Varicella-zoster virus (VZV) is a widespread human herpes virus causing chicken pox on primary infection and persisting in sensory neurons. Reactivation causes shingles, which are characterized by severe pain and often lead to postherpetic neuralgia. To elucidate the mechanisms of VZV-associated hyperalgesia, we elaborated an in vitro model for the VZV infection of sensory neurons from rat dorsal root ganglia. Between 35 and 50% of the neurons showed strong expression of the immediate-early virus antigens IE62 and IE63 and the late glycoprotein gE. When the intracellular calcium concentration was monitored microfluorometrically for individual cells after infection, the sensitivity to GABA or capsaicin was similar in controls and in VZV-infected neurons. However, the baseline calcium concentration was increased. Neurons became de novo sensitive to adrenergic stimulation after VZV infection. Norepinephrine-responsive neurons were more frequent and calcium responses to norepinephrine were significantly higher after infection with wild-type isolates than with the attenuated vaccine strain OKA. The adrenergic agonists phenylephrine and isoproterenol had similar efficacy. We suggest that the infection with wild-type VZV isolates confers norepinephrine sensitivity to sensory neurons by using alpha(1)- and/or beta(1)-adrenergic receptors providing a model for the pathophysiology of the severe pain associated with the acute reactivation of VZV.

  9. Upregulation of nuclear factor‑κB and acid sensing ion channel 3 in dorsal root ganglion following application of nucleus pulposus onto the nerve root in rats.

    PubMed

    Wang, Dong; Pan, Hao; Zhu, Hang; Zhu, Li; He, Yong-Jiang; Wang, Jian; Jia, Gao-Yong

    2017-10-01

    The nucleus pulposus (NP) is an avascular, hydrated tissue that permits the intervertebral disc to resist compressive loads to the spine. To determine the mechanisms by which intervertebral disc degeneration is caused by the nucleus pulposus, the expression and regulation of nuclear factor (NF)‑κB and acid sensing ion channel 3 (ASIC3) were examined. For the intervertebral disc degeneration model, NP was harvested from the tail of rats and applied to the L5 dorsal root ganglion (DRG). The mechanical pain withdrawal threshold (PWT) in NP model rats was assessed. Reverse transcription‑quantitative polymerase chain reaction and western blotting were used to examine NF‑κB and ASIC3 expression levels in DRG. Finally, the effect of the NF‑κB inhibitor pyrrolidine dithiocarbamate (PDTC) and the ASIC3 signaling pathway blocker amiloride were examined. Rats exposed to NP exhibited decreased PWT for 12 days, and NF‑κB and ASIC3 was upregulated in DRG induced by NP 14 days after surgery. After administration of amiloride and PDTC to DRG affected by NP, the levels of nitric oxide (NO), tumor necrosis factor‑α (TNF‑α), interleukin‑6 (IL‑6), NF‑κB and ASIC3 were downregulated, and the levels of aquaporin (AQP) 1 and AQP3 were significantly increased for 14 days. In conclusion, these results suggested that NF‑κB and ASIC3 may serve an important role in intervertebral disc degeneration caused by NP.

  10. Marked Increase in Nitric Oxide Synthase mRNA in Rat Dorsal Root Ganglia after Peripheral Axotomy: In situ Hybridization and Functional Studies

    NASA Astrophysics Data System (ADS)

    Verge, Valerie M. K.; Xu, Zhang; Xu, Xiao-Jun; Wiesenfeld-Hallin, Zsuzsanna; Hokfelt, Tomas

    1992-12-01

    Using in situ hybridization, we studied nitric oxide (NO) synthase (EC 1.14.23.-) mRNA in lumbar dorsal root ganglia after peripheral transection of the sciatic nerve in rats. The effect of the NO synthase inhibitor N^ω-nitro-L-arginine methyl ester on the nociceptive flexor reflex was also studied in axotomized rats. Nerve section induced a dramatic increase in number of NO synthase mRNA-positive cells in the ipsilateral dorsal root ganglia. In some of these cells the peptides galanin and/or vasoactive intestinal polypeptide and/or neuropeptide Y were also strongly up-regulated. Intravenous administration of nitro-L-arginine methyl ester blocked spinal hyperexcitability at much lower dosages in axotomized than in normal animals. The results suggest involvement of NO in the function of lumbar sensory neurons, especially after axotomy, perhaps preferentially at peripheral sites.

  11. Coculture system of keratinocytes and dorsal-root-ganglion-derived cells for screening neurotrophic factors involved in guidance of neuronal axon growth in the skin.

    PubMed

    Kumamoto, Jun-Ichi; Nakatani, Masashi; Tsutsumi, Moe; Goto, Makiko; Denda, Sumiko; Takei, Kentaro; Denda, Mitsuhiro

    2014-01-01

    The density of peripheral nerve fibres is increased in atopic dermatitis. Moreover, reduction in the fibres in a mouse model of atopic dermatitis reduces scratching behaviour. Thus, regulation of nerve fibre extension could be an effective strategy to reduce itching in pruritus dermatosis. In this study, we established a new coculture system of keratinocytes and dorsal-root-ganglion-derived cells using an apparatus, AXIS(™) , which consists of two different channels connected via a set of microgrooves, through which signalling molecules and axons, but not living cells, can pass. When we seeded keratinocytes in one chamber, extension of nerve fibres was observed from dorsal root ganglion cells seeded in the other chamber. Addition of anti-BDNF antibody in the keratinocyte-seeded chamber significantly reduced the extension. Application of Semaphorin 3A also reduced the extension by approximately 50%. We suggest that this coculture system may be useful for screening of anti-itching drugs.

  12. Selective plasticity of primary afferent innervation to the dorsal horn and autonomic nuclei following lumbosacral ventral root avulsion and reimplantation in long term studies.

    PubMed

    Wu, Lisa; Wu, Jun; Chang, Huiyi H; Havton, Leif A

    2012-02-01

    Previous studies involving injuries to the nerves of the cauda equina and the conus medullaris have shown that lumbosacral ventral root avulsion in rat models results in denervation and dysfunction of the lower urinary tract, retrograde and progressive cell death of the axotomized motor and parasympathetic neurons, as well as the emergence of neuropathic pain. Root reimplantation has also been shown to ameliorate several of these responses, but experiments thus far have been limited to studying the effects of lesion and reimplantation local to the lumbosacral region. Here, we have expanded the region of investigation after lumbosacral ventral root avulsion and reimplantation to include the thoracolumbar sympathetic region of the spinal cord. Using a retrograde tracer injected into the major pelvic ganglion, we were able to define the levels of the spinal cord that contain sympathetic preganglionic neurons innervating the lower urinary tract. We have conducted studies on the effects of the lumbosacral ventral root avulsion and reimplantation models on the afferent innervation of the dorsal horn and autonomic nuclei at both thoracolumbar and lumbosacral levels through immunohistochemistry for the markers calcitonin gene-related peptide (CGRP) and vesicular glutamate transporter 1 (VGLUT1). Surprisingly, our experiments reveal a selective and significant decrease of CGRP-positive innervation in the dorsal horn at thoracolumbar levels that is partially restored with root reimplantation. However, no similar changes were detected at the lumbosacral levels despite the injury and repair targeting efferent neurons, and being performed at the lumbosacral levels. Despite the changes evident in the thoracolumbar dorsal horn, we find no changes in afferent innervation of the autonomic nuclei at either sympathetic or parasympathetic segmental levels by CGRP or VGLUT1. We conclude that even remote, efferent root injuries and repair procedures can have an effect on remote and non

  13. One cell model establishment to inhibit CaMKIIγ mRNA expression in the dorsal root ganglion neuron by RNA interfere.

    PubMed

    Wen, Xianjie; Li, Xiaohong; Liang, Hua; Yang, Chenxiang; Zhong, Jiying; Wang, Hanbing; Liu, Hongzhen

    2017-09-01

    CaMKIIγ in dorsal root ganglion neurons is closely related to the neuropathic pain, neuron injury induced by local anesthetics. To get great insight into the function of CaMKIIγ in dorsal root ganglion neurons, we need one cell model to specially inhibit the CaMKIIγ mRNA expression. The present study was aimed to establish one cell model to specially inhibit the CaMKIIγ mRNA expression. We designed the CaMKIIγ shRNA sequence and connected with pYr-1.1 plasmid. The ligation product of the CaMKIIγshRNA and pYr-1.1 plasmid was recombined with pAd/PL-DEST vector into pAD-CaMKIIγ-shRNA. adenovirus vector. pAD-CaMKIIγ-shRNA. adenovirus vector infected the dorsal root ganglion neuron to inhibit the CaMKIIγ mRNA expression in vitro. The pAD-CaMKIIγ-shRNA adenovirus vector was verified to be correct by the digestion, sequence. And pAD-CaMKIIγ-shRNA. adenovirus vector can infect the DRG cells to inhibit the CaMKIIγ mRNA or protein expression by the real-time polymerase chain reaction (PCR) or western blotting. Those results showed that we successfully constructed one adenovirus vector that can infect the dorsal root ganglion neuron to inhibit the CaMKIIγ mRNA and protein expression. That will supply with one cell model for the CaMKIIγ function study.

  14. Downregulation of miR-219 enhances brain-derived neurotrophic factor production in mouse dorsal root ganglia to mediate morphine analgesic tolerance by upregulating CaMKIIγ

    PubMed Central

    Hu, Xue-Ming; Cao, Shou-Bin; Zhang, Hai-Long; Lyu, Dong-Mei; Chen, Li-Ping; Xu, Heng; Pan, Zhi-Qiang

    2016-01-01

    Background Increasing evidence suggests that microRNAs are functionally involved in the initiation and maintenance of pain hypersensitivity, including chronic morphine analgesic tolerance, through the posttranscriptional regulation of pain-related genes. We have previously demonstrated that miR-219 regulates inflammatory pain in the spinal cord by targeting calcium/calmodulin-dependent protein kinase II gamma (CaMKIIγ). However, whether miR-219 regulates CaMKIIγ expression in the dorsal root ganglia to mediate morphine tolerance remains unclear. Results MiR-219 expression was downregulated and CaMKIIγ expression was upregulated in mouse dorsal root ganglia following chronic morphine treatment. The changes in miR-219 and CaMKIIγ expression closely correlated with the development of morphine tolerance, which was measured using the reduction of percentage of maximum potential efficiency to thermal stimuli. Morphine tolerance was markedly delayed by upregulating miR-219 expression using miR-219 mimics or downregulating CaMKIIγ expression using CaMKIIγ small interfering RNA. The protein and mRNA expression of brain-derived neurotrophic factor were also induced in dorsal root ganglia by prolonged morphine exposure in a time-dependent manner, which were transcriptionally regulated by miR-219 and CaMKIIγ. Scavenging brain-derived neurotrophic factor via tyrosine receptor kinase B-Fc partially attenuated morphine tolerance. Moreover, functional inhibition of miR-219 via miR-219-sponge in naive mice elicited thermal hyperalgesia and spinal neuronal sensitization, which were both suppressed by CaMKIIγ small interfering RNA or tyrosine receptor kinase B-Fc. Conclusions These results demonstrate that miR-219 contributes to the development of chronic tolerance to morphine analgesia in mouse dorsal root ganglia by targeting CaMKIIγ and enhancing CaMKIIγ-dependent brain-derived neurotrophic factor expression. PMID:27599867

  15. Effect of FGF-2 and sciatic nerve grafting on ChAT expression in dorsal root ganglia neurons of spinal cord transected rats.

    PubMed

    Guzen, Fausto Pierdoná; de Araújo, Dayane Pessoa; Lucena, Eudes Euler de Souza; de Morais, Hécio Henrique Araújo; Cavalcanti, José Rodolfo Lopes de Paiva; do Nascimento, Expedito Silva; Costa, Miriam Stela Maris de Oliveira; Cavalcante, Jeferson Sousa

    2016-03-11

    Neurotrophic factors and peripheral nerves are known to be good substrates for bridging CNS trauma. The involvement of fibroblast growth factor-2 (FGF-2) activation in the dorsal root ganglion (DRG) was examined following spinal cord injury in the rat. We evaluated whether FGF-2 increases the ability of a sciatic nerve graft to enhance neuronal plasticity, in a gap promoted by complete transection of the spinal cord. The rats were subjected to a 4mm-long gap at low thoracic level and were repaired with saline (Saline or control group, n=10), or fragment of the sciatic nerve (Nerve group, n=10), or fragment of the sciatic nerve to which FGF-2 (Nerve+FGF-2 group, n=10) had been added immediately after lesion. The effects of the FGF-2 and fragment of the sciatic nerve grafts on neuronal plasticity were investigated using choline acetyl transferase (ChAT)-immunoreactivity of neurons in the dorsal root ganglion after 8 weeks. Preservation of the area and diameter of neuronal cell bodies in dorsal root ganglion (DRG) was seen in animals treated with the sciatic nerve, an effect enhanced by the addition of FGF-2. Thus, the addition of exogenous FGF-2 to a sciatic nerve fragment grafted in a gap of the rat spinal cord submitted to complete transection was able to improve neuroprotection in the DRG. The results emphasized that the manipulation of the microenvironment in the wound might amplify the regenerative capacity of peripheral neurons.

  16. Response of cervicogenic headaches and occipital neuralgia to radiofrequency ablation of the C2 dorsal root ganglion and/or third occipital nerve.

    PubMed

    Hamer, John F; Purath, Traci A

    2014-03-01

    This article investigates the degree and duration of pain relief from cervicogenic headaches or occipital neuralgia following treatment with radiofrequency ablation of the C2 dorsal root ganglion and/or third occipital nerves. It also addresses the procedure's complication rate and patient's willingness to repeat the procedure if severe symptoms recur. This is a single-center retrospective observational study of 40 patients with refractory cervicogenic headaches and or occipital neuralgia. Patients were all referred by a headache specialty clinic for evaluation for radiofrequency ablation of the C2 dorsal root ganglion and/or third occipital nerves. After treatment, patients were followed for a minimum of 6 months to a year. Patient demographics and the results of radiofrequency ablation were recorded on the same day, after 3-4 days, and at 6 months to 1 year following treatment. Thirty-five percent of patients reported 100% pain relief and 70% reported 80% or greater pain relief. The mean duration of improvement is 22.35 weeks. Complication rate was 12-13%. 92.5% of patients reported they would undergo the procedure again if severe symptoms returned. Radiofrequency ablation of the C2 dorsal root ganglion and/or third occipital nerve can provide many months of greater than 50% pain relief in the vast majority of recipients with an expected length of symptom improvement of 5-6 months. © 2014 American Headache Society.

  17. Expression of the immunoglobulin superfamily cell adhesion molecules in the developing spinal cord and dorsal root ganglion.

    PubMed

    Gu, Zirong; Imai, Fumiyasu; Kim, In Jung; Fujita, Hiroko; Katayama, Kei ichi; Mori, Kensaku; Yoshihara, Yoshihiro; Yoshida, Yutaka

    2015-01-01

    Cell adhesion molecules belonging to the immunoglobulin superfamily (IgSF) control synaptic specificity through hetero- or homophilic interactions in different regions of the nervous system. In the developing spinal cord, monosynaptic connections of exquisite specificity form between proprioceptive sensory neurons and motor neurons, however, it is not known whether IgSF molecules participate in regulating this process. To determine whether IgSF molecules influence the establishment of synaptic specificity in sensory-motor circuits, we examined the expression of 157 IgSF genes in the developing dorsal root ganglion (DRG) and spinal cord by in situ hybridization assays. We find that many IgSF genes are expressed by sensory and motor neurons in the mouse developing DRG and spinal cord. For instance, Alcam, Mcam, and Ocam are expressed by a subset of motor neurons in the ventral spinal cord. Further analyses show that Ocam is expressed by obturator but not quadriceps motor neurons, suggesting that Ocam may regulate sensory-motor specificity in these sensory-motor reflex arcs. Electrophysiological analysis shows no obvious defects in synaptic specificity of monosynaptic sensory-motor connections involving obturator and quadriceps motor neurons in Ocam mutant mice. Since a subset of Ocam+ motor neurons also express Alcam, Alcam or other functionally redundant IgSF molecules may compensate for Ocam in controlling sensory-motor specificity. Taken together, these results reveal that IgSF molecules are broadly expressed by sensory and motor neurons during development, and that Ocam and other IgSF molecules may have redundant functions in controlling the specificity of sensory-motor circuits.

  18. Phenotypic changes in dorsal root ganglion and spinal cord in the collagen antibody-induced arthritis mouse model.

    PubMed

    Su, Jie; Gao, Tianle; Shi, Tiejun; Xiang, Qiong; Xu, Xiaojun; Wiesenfeld-Hallin, Zsuzsanna; Hökfelt, Tomas; Svensson, Camilla I

    2015-07-01

    The mechanisms underlying rheumatoid arthritis (RA)-induced pain are still not fully elucidated, and accumulating data indicate that peripheral inflammation is not the only factor driving pain in these patients. The focus of our work is to investigate the molecular basis for long-term alterations in nociceptive pathways induced by polyarthritis using the collagen antibody-induced arthritis (CAIA) mouse model. In this model, mechanical hypersensitivity outlasts the joint inflammation by weeks. Here we examined expression levels of neuropeptides, ion channels, and nerve injury markers associated with neuropathic and/or inflammatory pain in dorsal root ganglia (DRGs) and spinal cord both during the peak of inflammation (day 15) and when the inflammation has resolved but the hypersensitivity persists (days 45-47). No apparent differences were observed in substance P, calcitonin gene-related peptide, or neuropeptide Y protein expression in DRGs and spinal cord of CAIA mice. However, the neuropeptide galanin, the ATP-gated ion channel P2X3, and calcium channel subunit α2δ1 were significantly increased in the CAIA DRGs as compared to controls, both 15 and 47 days after induction of arthritis. On day 15 there was an increase in expression of two factors associated with nerve injury and cell stress, activating transcription factor 3 and growth-associated protein 43 in DRGs, whereby the latter was still dramatically upregulated after 47 days. In conclusion, this study suggests that long-term joint inflammation has an impact on DRG neurons that resembles both inflammation and nerve injury-induced pain states. Thus, antibody-driven inflammation generates a pain state with a unique neurochemical profile. © 2015 Wiley Periodicals, Inc.

  19. Nociceptor-like rat dorsal root ganglion neurons express the angiotensin-II AT2 receptor throughout development.

    PubMed

    Benitez, Sergio; Seltzer, Alicia; Acosta, Cristian

    2017-02-01

    AT2 receptor (AT2R) plays a functional role in foetal development. Its expression declines in most tissues soon after birth but stays high in sensory areas of the adult nervous system. In the dorsal root ganglia (DRG) the expression pattern of AT2R during development and the identity of the subpopulation expressing it remain unknown. Using a combination of semi-quantitative PCR, western blotting and immunohistochemistry we examined the expression of AT2R at mRNA and protein levels in rat DRGs from embryonic day 15 (E15) until postnatal day 30 (PN30). We found that both AT2R mRNA and protein levels exhibited only minor (statistically non-significant) fluctuations from E15 to PN30. Detailed quantitative analysis of ABC/DAB AT2R staining showed a) that the receptor was present in most neurons at E15 and E18 and b) that postnatally it was predominantly expressed by small DRG neurons. Given that small neurons are putative C-nociceptors and the proposed role of AT2R in neuropathic pain, we next examined whether these AT2R-positive neurons co-localized with Ret and trkA embryonically and with IB4-binding postnatally. Most AT2R-positive neurons expressed trkA embryonically and bound IB4 postnatally. We found strong positive statistically highly significant correlations between AT2R cytoplasmic%intensities and trkA at E15/E18 and with Ret only at E18. Cytoplasmic AT2R also strongly and positively correlated with IB4-binding at PN3, 15 and 30. Our demonstration that a subpopulation of C-nociceptor-like neurons expresses AT2R during development supports a role for this receptor in neuropathic pain.

  20. Light-evoked somatosensory perception of transgenic rats that express channelrhodopsin-2 in dorsal root ganglion cells.

    PubMed

    Ji, Zhi-Gang; Ito, Shin; Honjoh, Tatsuya; Ohta, Hiroyuki; Ishizuka, Toru; Fukazawa, Yugo; Yawo, Hiromu

    2012-01-01

    In vertebrate somatosensory systems, each mode of touch-pressure, temperature or pain is sensed by sensory endings of different dorsal root ganglion (DRG) neurons, which conducted to the specific cortical loci as nerve impulses. Therefore, direct electrical stimulation of the peripheral nerve endings causes an erroneous sensation to be conducted by the nerve. We have recently generated several transgenic lines of rat in which channelrhodopsin-2 (ChR2) transgene is driven by the Thy-1.2 promoter. In one of them, W-TChR2V4, some neurons were endowed with photosensitivity by the introduction of the ChR2 gene, coding an algal photoreceptor molecule. The DRG neurons expressing ChR2 were immunohistochemically identified using specific antibodies to the markers of mechanoreceptive or nociceptive neurons. Their peripheral nerve endings in the plantar skin as well as the central endings in the spinal cord were also examined. We identified that ChR2 is expressed in a certain population of large neurons in the DRG of W-TChR2V4. On the basis of their morphology and molecular markers, these neurons were classified as mechanoreceptive but not nociceptive. ChR2 was also distributed in their peripheral sensory nerve endings, some of which were closely associated with CK20-positive cells to form Merkel cell-neurite complexes or with S-100-positive cells to form structures like Meissner's corpuscles. These nerve endings are thus suggested to be involved in the sensing of touch. Each W-TChR2V4 rat showed a sensory-evoked behavior in response to blue LED flashes on the plantar skin. It is thus suggested that each rat acquired an unusual sensory modality of sensing blue light through the skin as touch-pressure. This light-evoked somatosensory perception should facilitate study of how the complex tactile sense emerges in the brain.

  1. Dorsoventral organization of sensory nerves in the lumbar spine as indicated by double labeling of dorsal root ganglion neurons.

    PubMed

    Takahashi, Yuzuru; Ohtori, Seiji; Takahashi, Kazuhisa

    2010-07-01

    Referred pain due to lumbar disc disorders can be analyzed using the stereoscopic structure of the peripheral sensory nervous system. The rostrocaudal structure has been clarified. The dorsoventral structure of the lumbar spine would be useful for mapping areas of pain perception in spinal disorders. The neurotracer 1,1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine perchlorate (DiI) was applied to the lateral portion of the L5/6 intervertebral disc in rats to examine the dorsoventral organization of the sensory nervous system in the lumbar spine and related tissues. Fluorogold (FG) was applied to reference sites located at the spinous process of the L5 vertebra, the L5/6 facet joint, the psoas muscle at the L5 level, or the rectus abdominis muscle at the pubic symphysis. FG was also applied to the lateral portion of the disc (DiI application site) at L5 or at the L5 level as controls for the double labeling. Labeled neurons were counted in dorsal root ganglia (DRGs) from L1 through L4. The proportion of neurons double-labeled with DiI and FG in the total number of DiI-labeled and FG-labeled neurons was 32.9% in the control group; 0% in the spinous process, 0.6% in the facet joint, 2.3% in the psoas muscle, and 0.1% in the rectus abdominis muscle. DRG neurons with dichotomizing afferent fibers were most prevalent (2.3%) between the lateral disc and the psoas muscle at the groin; they were rare or absent between the disc and other reference sites. Dorsoventral organization of the primary sensory system in the lumbar body trunk was suggested from the proportion of DRG neurons with dichotomizing afferent fibers innervating the lumbar disc and other tissues. The present findings provide a pathomechanism of groin referred pain in lumbar disc disorders.

  2. Pharmacological and molecular characterization of a dorsal root ganglion cell line expressing cannabinoid CB(1) and CB(2) receptors.

    PubMed

    Fan, Yihong; Hooker, Bradley A; Garrison, Tiffany Runyan; El-Kouhen, Odile F; Idler, Kenneth B; Holley-Shanks, Rhonda R; Meyer, Michael D; Yao, Betty Bei

    2011-06-01

    The behavioral effects evoked by cannabinoids are primarily mediated by the CB(1) and CB(2) cannabinoid receptor subtypes. In vitro pharmacology of cannabinoid receptors has been elucidated using recombinant expression systems expressing either CB(1) or CB(2) receptors, with limited characterization in native cell lines endogenously expressing both CB(1) and CB(2) receptors. In the current study, we report the molecular and pharmacological characterization of the F-11 cell line, a hybridoma of rat dorsal root ganglion neurons and mouse neuroblastoma (N18TG2) cells, reported to endogenously express both cannabinoid receptors. The present study revealed that both receptors are of mouse origin in F-11 cells, and describes the relative gene expression levels between the two receptors. Pharmacological characterization of the F-11 cell line using cannabinoid agonists and antagonists indicated that the functional responses to these cannabinoid ligands are mainly mediated by CB(1) receptors. The non-selective cannabinoid ligands CP 55,940 and WIN 55212-2 are potent agonists and their efficacies in adenylate cyclase and MAPK assays are inhibited by the CB(1) selective antagonist SR141716A (SR1), but not by the CB(2) selective antagonist SR144528 (SR2). The endocannabinoid ligand 2AG, although not active in adenylate cyclase assays, was a potent activator of MAPK signaling in F-11 cells. The analysis of CB(1) and CB(2) receptor gene expression and the characterization of cannabinoid receptor pharmacology in the F-11 cell line demonstrate that it can be used as a tool for interrogating the endogenous signal transduction of cannabinoid receptor subtypes.

  3. Glutathione modulates Ca(2+) influx and oxidative toxicity through TRPM2 channel in rat dorsal root ganglion neurons.

    PubMed

    Nazıroğlu, Mustafa; Özgül, Cemil; Çiğ, Bilal; Doğan, Salih; Uğuz, Abdulhadi Cihangir

    2011-08-01

    Glutathione (GSH) is the most abundant thiol antioxidant in mammalian cells and maintains thiol redox in the cells. GSH depletion has been implicated in the neurobiology of sensory neurons. Because the mechanisms that lead to melastatin-like transient receptor potential 2 (TRPM2) channel activation/inhibition in response to glutathione depletion and 2-aminoethyldiphenyl borinate (2-APB) administration are not understood, we tested the effects of 2-APB and GSH on oxidative stress and buthionine sulfoximine (BSO)-induced TRPM2 cation channel currents in dorsal root ganglion (DRG) neurons of rats. DRG neurons were freshly isolated from rats and the neurons were incubated for 24 h with BSO. In whole-cell patch clamp experiments, TRPM2 currents in the rat were consistently induced by H(2)O(2) or BSO. TRPM2 channels current densities and cytosolic free Ca(2+) content of the neurons were higher in BSO and H(2)O(2) groups than in control. However, the current densities and cytosolic Ca(2+) release were also higher in the BSO + H(2)O(2) group than in the H(2)O(2) alone. When intracellular GSH is introduced by pipette TRPM2 channel currents were not activated by BSO, H(2)O(2) or rotenone. BSO and H(2)O(2)-induced Ca(2+) gates were blocked by the 2-APB. Glutathione peroxidase activity, lipid peroxidation and GSH levels in the DRG neurons were also modulated by GSH and 2-APB inhibition. In conclusion, we observed the protective role of 2-APB and GSH on Ca(2+) influx through a TRPM2 channel in intracellular GSH depleted DRG neurons. Since cytosolic glutathione depletion is a common feature of neuropathic pain and diseases of sensory neuron, our findings are relevant to the etiology of neuropathology in DRG neurons.

  4. Oxaliplatin-Induced Peripheral Neuropathy via TRPA1 Stimulation in Mice Dorsal Root Ganglion Is Correlated with Aluminum Accumulation

    PubMed Central

    Roh, Kangsan; Kil, Eui-Joon; Lee, Minji; Auh, Chung-Kyun; Lee, Myung-Ah; Yeom, Chang-Hwan; Lee, Sukchan

    2015-01-01

    Oxaliplatin is a platinum-based anticancer drug used to treat metastatic colorectal, breast, and lung cancers. While oxaliplatin kills cancer cells effectively, it exhibits several side effects of varying severity. Neuropathic pain is commonly experienced during treatment with oxaliplatin. Patients describe symptoms of paresthesias or dysesthesias that are triggered by cold (acute neuropathy), or as abnormal sensory or motor function (chronic neuropathy). In particular, we found that aluminum levels were relatively high in some cancer patients suffering from neuropathic pain based on clinical observations. Based on these findings, we hypothesized that aluminum accumulation in the dorsal root ganglion (DRG) in the course of oxaliplatin treatment exacerbates neuropathic pain. In mice injected with oxaliplatin (three cycles of 3 mg/kg i.p. daily for 5 days, followed by 5 days of rest), we detected cold allodynia using the acetone test, but not heat hyperalgesia using a hot plate. However, co-treatment with aluminum chloride (AlCl3∙6H2O; 7 mg/kg i.p. for 14 days: equivalent 0.78 mg/kg of elemental Al) and oxaliplatin (1 cycle of 3 mg/kg i.p. daily for 5 days, followed by 5 days of rest) synergistically induced cold allodynia as well as increased TRPAl mRNA and protein expression. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis showed a significant increase in aluminum concentrations in the DRG of mice treated with aluminum chloride and oxaliplatin compared to aluminum chloride alone. Similarly, in a mouse induced-tumor model, aluminum concentrations were increased in DRG tissue and tumor cells after oxaliplatin treatment. Taken together, these findings suggest that aluminum accumulation in the DRG may exacerbate neuropathic pain in oxaliplatin-treated mice. PMID:25928068

  5. Comparison of dorsal root ganglion gene expression in rat models of traumatic and HIV-associated neuropathic pain.

    PubMed

    Maratou, Klio; Wallace, Victoria C J; Hasnie, Fauzia S; Okuse, Kenji; Hosseini, Ramine; Jina, Nipurna; Blackbeard, Julie; Pheby, Timothy; Orengo, Christine; Dickenson, Anthony H; McMahon, Stephen B; Rice, Andrew S C

    2009-04-01

    To elucidate the mechanisms underlying peripheral neuropathic pain in the context of HIV infection and antiretroviral therapy, we measured gene expression in dorsal root ganglia (DRG) of rats subjected to systemic treatment with the anti-retroviral agent, ddC (Zalcitabine) and concomitant delivery of HIV-gp120 to the rat sciatic nerve. L4 and L5 DRGs were collected at day 14 (time of peak behavioural change) and changes in gene expression were measured using Affymetrix whole genome rat arrays. Conventional analysis of this data set and Gene Set Enrichment Analysis (GSEA) was performed to discover biological processes altered in this model. Transcripts associated with G protein coupled receptor signalling and cell adhesion were enriched in the treated animals, while ribosomal proteins and proteasome pathways were associated with gene down-regulation. To identify genes that are directly relevant to neuropathic mechanical hypersensitivity, as opposed to epiphenomena associated with other aspects of the response to a sciatic nerve lesion, we compared the gp120+ddC-evoked gene expression with that observed in a model of traumatic neuropathic pain (L5 spinal nerve transection), where hypersensitivity to a static mechanical stimulus is also observed. We identified 39 genes/expressed sequence tags that are differentially expressed in the same direction in both models. Most of these have not previously been implicated in mechanical hypersensitivity and may represent novel targets for therapeutic intervention. As an external control, the RNA expression of three genes was examined by RT-PCR, while the protein levels of two were studied using western blot analysis.

  6. Comparison of dorsal root ganglion gene expression in rat models of traumatic and HIV-associated neuropathic pain

    PubMed Central

    Maratou, Klio; Wallace, Victoria C.J.; Hasnie, Fauzia S.; Okuse, Kenji; Hosseini, Ramine; Jina, Nipurna; Blackbeard, Julie; Pheby, Timothy; Orengo, Christine; Dickenson, Anthony H.; McMahon, Stephen B.; Rice, Andrew S.C.

    2009-01-01

    To elucidate the mechanisms underlying peripheral neuropathic pain in the context of HIV infection and antiretroviral therapy, we measured gene expression in dorsal root ganglia (DRG) of rats subjected to systemic treatment with the anti-retroviral agent, ddC (Zalcitabine) and concomitant delivery of HIV-gp120 to the rat sciatic nerve. L4 and L5 DRGs were collected at day 14 (time of peak behavioural change) and changes in gene expression were measured using Affymetrix whole genome rat arrays. Conventional analysis of this data set and Gene Set Enrichment Analysis (GSEA) was performed to discover biological processes altered in this model. Transcripts associated with G protein coupled receptor signalling and cell adhesion were enriched in the treated animals, while ribosomal proteins and proteasome pathways were associated with gene down-regulation. To identify genes that are directly relevant to neuropathic mechanical hypersensitivity, as opposed to epiphenomena associated with other aspects of the response to a sciatic nerve lesion, we compared the gp120 + ddC-evoked gene expression with that observed in a model of traumatic neuropathic pain (L5 spinal nerve transection), where hypersensitivity to a static mechanical stimulus is also observed. We identified 39 genes/expressed sequence tags that are differentially expressed in the same direction in both models. Most of these have not previously been implicated in mechanical hypersensitivity and may represent novel targets for therapeutic intervention. As an external control, the RNA expression of three genes was examined by RT-PCR, while the protein levels of two were studied using western blot analysis. PMID:18606552

  7. G(o) transduces GABAB-receptor modulation of N-type calcium channels in cultured dorsal root ganglion neurons.

    PubMed

    Menon-Johansson, A S; Berrow, N; Dolphin, A C

    1993-11-01

    High-voltage-activated (HVA) calcium channel currents (IBa) were recorded from acutely replated cultured dorsal root ganglion (DRG) neurons. IBa was irreversibly inhibited by 56.9 +/- 2.7% by 1 microM omega-conotoxin-GVIA (omega-CTx-GVIA), whereas the 1,4-dihydropyridine antagonist nicardipine was ineffective. The selective gamma-aminobutyric acidB (GABAB) agonist, (-)-baclofen (50 microM), inhibited the HVA IBa by 30.7 +/- 5.4%. Prior application of omega-CTx-GVIA completely occluded inhibition of the HVA IBa by (-)-baclofen, indicating that in this preparation (-)-baclofen inhibits N-type current. To investigate which G protein subtype was involved, cells were replated in the presence of anti-G protein antisera. Under these conditions the antibodies were shown to enter the cells through transient pores created during the replating procedure. Replating DRGs in the presence of anti-G(o) antiserum, raised against the C-terminal decapeptide of the G alpha o subunit, reduced (-)-baclofen inhibition of the HVA IBa, whereas replating DRGs in the presence of the anti-Gi antiserum did not. Using anti-G alpha o antisera (1:2000) and confocal laser microscopy, G alpha o localisation was investigated in both unreplated and replated neurons. G alpha o immunoreactivity was observed at the plasma membrane, neurites, attachment plaques and perinuclear region, and was particularly pronounced at points of cell-to-cell contact. The plasma membrane G alpha o immunoreactivity was completely blocked by preincubation with the immunising G alpha o undecapeptide (1 microgram.ml-1) for 1 h at 37 degrees C. A similar treatment also blocked recognition of G alpha o in brain membranes on immunoblots.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. The aminoglycosides modulate the acid-sensing ionic channel currents in dorsal root ganglion neurons from the rat.

    PubMed

    Garza, Aníbal; López-Ramírez, Omar; Vega, Rosario; Soto, Enrique

    2010-02-01

    Acid-sensing ionic channels (ASICs) have been shown to have a significant role in a growing number of physiological and pathological processes, such as nociception, synaptic transmission and plasticity, mechanosensation, and acidosis-induced neuronal injury. The discovery of pharmacological agents targeting ASICs has significant therapeutic potential and use as a research tool. In our work, we studied the action of transient perfusion (5-15 s) of aminoglycosides (AGs) (streptomycin and neomycin) on the proton-gated ionic currents in dorsal root ganglion (DRG) neurons of the rat and in human embryonic kidney (HEK)-293 cells. In DRG neurons, streptomycin and neomycin (30 microM) produced a significant, concentration-dependent, and reversible reduction in the amplitude of the proton-gated current, and a slowing of the desensitization rate of the ASIC current. Gentamycin (30 microM) also showed a significant reversible action on the ASIC currents. The curves of the pH effect for streptomycin and neomycin indicated that their effect was not significantly affected by pH. In HEK-293 cells, streptomycin (30 microM) produced a significant reduction in the amplitude of the proton-gated current. Neomycin and gentamycin had no significant action. Reduction of extracellular Ca(2+) concentration produced a significant increase in the action of streptomycin and neomycin on the desensitization time course of ASIC currents. These results indicate that ASICs are molecular targets for AGs, which may contribute to the understanding of their actions on excitable cells. Moreover, AGs may constitute a source to develop novel molecules with a greater affinity, specificity, and selectivity for the different ASIC subunits.

  9. Pyruvate Dehydrogenase Kinase-mediated Glycolytic Metabolic Shift in the Dorsal Root Ganglion Drives Painful Diabetic Neuropathy.

    PubMed

    Rahman, Md Habibur; Jha, Mithilesh Kumar; Kim, Jong-Heon; Nam, Youngpyo; Lee, Maan Gee; Go, Younghoon; Harris, Robert A; Park, Dong Ho; Kook, Hyun; Lee, In-Kyu; Suk, Kyoungho

    2016-03-11

    The dorsal root ganglion (DRG) is a highly vulnerable site in diabetic neuropathy. Under diabetic conditions, the DRG is subjected to tissue ischemia or lower ambient oxygen tension that leads to aberrant metabolic functions. Metabolic dysfunctions have been documented to play a crucial role in the pathogenesis of diverse pain hypersensitivities. However, the contribution of diabetes-induced metabolic dysfunctions in the DRG to the pathogenesis of painful diabetic neuropathy remains ill-explored. In this study, we report that pyruvate dehydrogenase kinases (PDK2 and PDK4), key regulatory enzymes in glucose metabolism, mediate glycolytic metabolic shift in the DRG leading to painful diabetic neuropathy. Streptozotocin-induced diabetes substantially enhanced the expression and activity of the PDKs in the DRG, and the genetic ablation of Pdk2 and Pdk4 attenuated the hyperglycemia-induced pain hypersensitivity. Mechanistically, Pdk2/4 deficiency inhibited the diabetes-induced lactate surge, expression of pain-related ion channels, activation of satellite glial cells, and infiltration of macrophages in the DRG, in addition to reducing central sensitization and neuroinflammation hallmarks in the spinal cord, which probably accounts for the attenuated pain hypersensitivity. Pdk2/4-deficient mice were partly resistant to the diabetes-induced loss of peripheral nerve structure and function. Furthermore, in the experiments using DRG neuron cultures, lactic acid treatment enhanced the expression of the ion channels and compromised cell viability. Finally, the pharmacological inhibition of DRG PDKs or lactic acid production substantially attenuated diabetes-induced pain hypersensitivity. Taken together, PDK2/4 induction and the subsequent lactate surge induce the metabolic shift in the diabetic DRG, thereby contributing to the pathogenesis of painful diabetic neuropathy.

  10. Shp-1 dephosphorylates TRPV1 in dorsal root ganglion neurons and alleviates CFA-induced inflammatory pain in rats.

    PubMed

    Xiao, Xing; Zhao, Xiao-Tao; Xu, Ling-Chi; Yue, Lu-Peng; Liu, Feng-Yu; Cai, Jie; Liao, Fei-Fei; Kong, Jin-Ge; Xing, Guo-Gang; Yi, Ming; Wan, You

    2015-04-01

    Transient receptor potential vanilloid 1 (TRPV1) receptors are expressed in nociceptive neurons of rat dorsal root ganglions (DRGs) and mediate inflammatory pain. Nonspecific inhibition of protein-tyrosine phosphatases (PTPs) increases the tyrosine phosphorylation of TRPV1 and sensitizes TRPV1. However, less is known about tyrosine phosphorylation's implication in inflammatory pain, compared with that of serine/threonine phosphorylation. Src homology 2 domain-containing tyrosine phosphatase 1 (Shp-1) is a key phosphatase dephosphorylating TRPV1. In this study, we reported that Shp-1 colocalized with and bound to TRPV1 in nociceptive DRG neurons. Shp-1 inhibitors, including sodium stibogluconate and PTP inhibitor III, sensitized TRPV1 in cultured DRG neurons. In naive rats, intrathecal injection of Shp-1 inhibitors increased both TRPV1 and tyrosine-phosphorylated TRPV1 in DRGs and induced thermal hyperalgesia, which was abolished by pretreatment with TRPV1 antagonists capsazepine, BCTC, or AMG9810. Complete Freund's adjuvant (CFA)-induced inflammatory pain in rats significantly increased the expression of Shp-1, TRPV1, and tyrosine-phosphorylated TRPV1, as well as the colocalization of Shp-1 and TRPV1 in DRGs. Intrathecal injection of sodium stibogluconate aggravated CFA-induced inflammatory pain, whereas Shp-1 overexpression in DRG neurons alleviated it. These results suggested that Shp-1 dephosphorylated and inhibited TRPV1 in DRG neurons, contributing to maintain thermal nociceptive thresholds in normal rats, and as a compensatory mechanism, Shp-1 increased in DRGs of rats with CFA-induced inflammatory pain, which was involved in protecting against excessive thermal hyperalgesia.

  11. Forced treadmill running suppresses postincisional pain and inhibits upregulation of substance P and cytokines in rat dorsal root ganglion.

    PubMed

    Chen, Yu-Wen; Tzeng, Jann-Inn; Lin, Min-Fei; Hung, Ching-Hsia; Wang, Jhi-Joung

    2014-08-01

    Exercise causes a variety of psychophysical effects (eg, alterations in pain sensation). Tissue injury induces mediator releases in the spinal cord resulting in pain hypersensitivity; however, the contribution of the dorsal root ganglion (DRG) is poorly understood. In this study, we tested if forced treadmill running can attenuate postoperative pain and alter substance P (SP) or proinflammatory cytokine level in the DRG by using a rat model of skin/muscle incision and retraction (SMIR). We evaluated mechanical sensitivity to von Frey stimuli (6 and 15 g) and expression of SP, interleukin-1β, and interleukin-6 in the DRG of sham-operated sedentary rats, SMIR sedentary rats, sham-operated rats with forced treadmill running, and SMIR rats with forced treadmill running. At postoperative day 8, trained rats ran for 5 days per week for 4 weeks on a treadmill 70 minutes/d with an intensity of 18 m/min. On postoperative day 6, SMIR sedentary rats displayed a significant mechanical hypersensitivity that persisted until postoperative day 35. By comparison, SMIR-operated rats, which received forced treadmill running, exhibited a quick recovery from mechanical hypersensitivity. SMIR sedentary rats showed an upregulation of SP, interleukin-1β, and interleukin-6 in the DRG at postoperative days 14 and 28, whereas SMIR-operated rats receiving forced treadmill running reversed this upregulation at postoperative day 28. We concluded that forced treadmill running alleviated persistent postincisional pain caused by SMIR surgery. This appears to be protective against postoperative pain, which probably relates to the downturn in excess SP, interleukin-1β, and interleukin-6 in the DRG. Controlling the expression of SP, interleukin-6, and interleukin-1β in the DRG can help manage postoperative pain. This finding could potentially help clinicians and physical therapists who seek to examine how exercise may attenuate postsurgical pain and its mechanism. Copyright © 2014 American Pain

  12. No further loss of dorsal root ganglion cells after axotomy in p75 neurotrophin receptor knockout mice.

    PubMed

    Sørensen, Bodil; Tandrup, Trine; Koltzenburg, Martin; Jakobsen, Johannes

    2003-05-05

    The role of the p75 neurotrophin receptor for neuronal survival after nerve crush was studied in L5 dorsal root ganglia (DRG) of knockout mice and controls with assumption-free stereological methods. Numbers of neuronal A- and B-cells were obtained using the optical fractionator and optical disector techniques. At birth, the total number of DRG neurons was 10,000 +/- 2,600 in control mice compared with 5,100 +/- 1,300 in p75 knockout mice. During postnatal development, 1,400 neuronal B-cell bodies were lost in p75 knockouts (2P < 0.05) and 1,100 in controls (NS), whereas the A-cell population remained stable. After a sciatic nerve crush, the total neuron loss in controls was 15.4% +/- 3.5% (2P < 0.05) and 22.7% +/- 5.1% (2P < 0.05) at days 14 and 42, respectively. In contrast, there was no loss in total number of neurons after crush in p75 knockout mice. Neuronal A-cell number was unchanged after the crush in p75 knockouts as well as in controls at both times. At 14 days, the population of B-cells was reduced by 24.8% +/- 3.6% in controls and by 6.1% +/- 3.5% in p75 knockouts, this difference being significant (2P < 0.001). At 42 days, the B-cell loss was 29.6% +/- 5.5% in controls and 4.2% +/- 6.4% in p75 knockouts (2P < 0.001). In conclusion, the lack of the p75 receptor results in neuronal DRG cells that are resistant to nerve injury, pointing to a role for the receptor in apoptosis. Copyright 2003 Wiley-Liss, Inc.

  13. Neuropathy-associated Nav1.7 variant I228M impairs integrity of dorsal root ganglion neuron axons.

    PubMed

    Persson, Anna-Karin; Liu, Shujun; Faber, Catharina G; Merkies, Ingemar S J; Black, Joel A; Waxman, Stephen G

    2013-01-01

    Small-fiber neuropathy (SFN) is characterized by injury to small-diameter peripheral nerve axons and intraepidermal nerve fibers (IENF). Although mechanisms underlying loss of IENF in SFN are poorly understood, available data suggest that it results from axonal degeneration and reduced regenerative capacity. Gain-of-function variants in sodium channel Na(V)1.7 that increase firing frequency and spontaneous firing of dorsal root ganglion (DRG) neurons have recently been identified in ∼30% of patients with idiopathic SFN. In the present study, to determine whether these channel variants can impair axonal integrity, we developed an in vitro assay of DRG neurite length, and examined the effect of 3 SFN-associated variant Na(V)1.7 channels, I228M, M932L/V991L (ML/VL), and I720K, on DRG neurites in vitro. At 3 days after culturing, DRG neurons transfected with I228M channels exhibited ∼20% reduced neurite length compared to wild-type channels; DRG neurons transfected with ML/VL and I720K variants displayed a trend toward reduced neurite length. I228M-induced reduction in neurite length was ameliorated by the use-dependent sodium channel blocker carbamazepine and by a blocker of reverse Na-Ca exchange. These in vitro observations provide evidence supporting a contribution of the I228M variant Na(V)1.7 channel to impaired regeneration and/or degeneration of sensory axons in idiopathic SFN, and suggest that enhanced sodium channel activity and reverse Na-Ca exchange can contribute to a decrease in length of peripheral sensory axons.

  14. Despite Differences in Cytosolic Calcium Regulation, Lidocaine Toxicity Is Similar in Adult and Neonatal Rat Dorsal Root Ganglia in Vitro

    PubMed Central

    Doan, Lisa V.; Eydlin, Olga; Piskoun, Boris; Kline, Richard P; Recio-Pinto, Esperanza; Rosenberg, Andrew D; Blanck, Thomas JJ; Xu, Fang

    2013-01-01

    Background Neuraxial local anesthetics may have neurological complications thought to be due to neurotoxicity. A primary site of action for local anesthetics is the dorsal root ganglia (DRG) neuron. Physiologic differences have been noted between young and adult DRG neurons; hence, we examined whether there were differences in lidocaine-induced changes in calcium and lidocaine toxicity in neonatal and adult rat DRG neurons. Methods DRG neurons were cultured from postnatal day 7 (P7) and adult rats. Lidocaine-induced changes in cytosolic calcium were examined with the calcium indicator Fluo-4. Cells were incubated with varying concentrations of lidocaine and examined for viability using calcein AM and ethidium homodimer-1 staining. Live imaging of caspase-3/7 activation was performed after incubation with lidocaine. Results The mean KCl-induced calcium transient was greater in P7 neurons (p < 0.05), and lidocaine significantly inhibited KCl-induced calcium responses in both ages (p < 0.05). Frequency distribution histograms of KCl-evoked calcium increases were more heterogeneous in P7 than in adult neurons. With lidocaine, KCl-induced calcium transients in both ages became more homogeneous but remained different between the groups. Interestingly cell viability was decreased by lidocaine in a dose-dependent manner similarly in both ages. Lidocaine treatment also activated caspase-3/7 in a dose- and time-dependent manner similarly in both ages. Conclusions Despite physiological differences in P7 and adult DRG neurons, lidocaine cytotoxicity is similar in P7 and adult DRG neurons in vitro. Differences in lidocaine- and KCl-evoked calcium responses suggest the similarity in lidocaine cytotoxicity involves other actions in addition to lidocaine-evoked effects on cytosolic calcium responses. PMID:23851347

  15. Melatonin Suppresses Neuropathic Pain via MT2-Dependent and -Independent Pathways in Dorsal Root Ganglia Neurons of Mice

    PubMed Central

    Lin, Jia-Ji; Lin, Ye; Zhao, Tian-Zhi; Zhang, Chun-Kui; Zhang, Ting; Chen, Xiao-Li; Ding, Jia-Qi; Chang, Ting; Zhang, Zhuo; Sun, Chao; Zhao, Dai-Di; Zhu, Jun-Lin; Li, Zhu-Yi; Li, Jin-Lian

    2017-01-01

    Melatonin (Mel) and its receptors (MT1 and MT2) have a well-documented efficacy in treating different pain conditions. However, the anti-nociceptive effects of Mel and Mel receptors in neuropathic pain (NP) are poorly understood. To elucidate this process, pain behaviors were measured in a dorsal root ganglia (DRG)-friendly sciatic nerve cuffing model. We detected up-regulation of MT2 expression in the DRGs of cuff-implanted mice and its activation by the agonist 8-M-PDOT (8MP). Also, Mel attenuated the mechanical and thermal allodynia induced by cuff implantation. Immunohistochemical analysis demonstrated the expression of MT2 in the DRG neurons, while MT1 was expressed in the satellite cells. In cultured primary neurons, microarray analysis and gene knockdown experiments demonstrated that MT2 activation by 8MP or Mel suppressed calcium signaling pathways via MAPK1, which were blocked by RAR-related orphan receptor alpha (RORα) activation with a high dose of Mel. Furthermore, expression of nitric oxide synthase 1 (NOS1) was down-regulated upon Mel treatment regardless of MT2 or RORα. Application of Mel or 8MP in cuff-implanted models inhibited the activation of peptidergic neurons and neuro-inflammation in the DRGs by down-regulating c-fos, calcitonin gene-related peptide [CGRP], and tumor necrosis factor-1α [TNF-1α] and interleukin-1β [IL-1β]. Addition of the MT2 antagonist luzindole blocked the effects of 8MP but not those of Mel. In conclusion, only MT2 was expressed in the DRG neurons and up-regulated upon cuff implantation. The analgesic effects of Mel in cuff-implanted mice were closely associated with both MT2-dependent (MAPK-calcium channels) and MT2-independent (NOS1) pathways in the DRG. PMID:28656058

  16. Sciatic nerve injury induces apoptosis of dorsal root ganglion satellite glial cells and selectively modifies neurosteroidogenesis in sensory neurons.

    PubMed

    Schaeffer, Véronique; Meyer, Laurence; Patte-Mensah, Christine; Eckert, Anne; Mensah-Nyagan, Ayikoe G

    2010-01-15

    Neurosteroids are synthesized either by glial cells, by neurons, or within the context of neuron-glia cross-talk. Various studies suggested neurosteroid involvement in the control of neurodegeneration but there is no evidence showing that the natural protection of nerve cells against apoptosis directly depends on their own capacity to produce neuroprotective neurosteroids. Here, we investigated the interactions between neurosteroidogenesis and apoptosis occurring in sensory structures of rats subjected to neuropathic pain generated by sciatic nerve chronic constriction injury (CCI). Using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), we observed no apoptotic cells in the spinal cord up to 30 days after CCI although pain symptoms such as mechano-allodynia, thermal and mechanical hyperalgesia were evidenced with the Hargreaves's behavioral and von Frey filament tests. In contrast, double-labeling experiments combining TUNEL and immunostaining with antibodies against glutamine synthetase or neuronal nuclei protein revealed apoptosis occurrence in satellite glial cells (SGC) (not in neurons) of CCI rat ipsilateral dorsal root ganglia (DRG) at day 30 after injury. Pulse-chase experiments coupled with high performance liquid chromatography and flow scintillation detection showed that, among numerous biosynthetic pathways converting [(3)H]pregnenolone into various [(3)H]neurosteroids, only [(3)H]estradiol formation was selectively modified and upregulated in DRG of CCI rats. Consistently, immunohistochemical investigations localized aromatase (estradiol-synthesizing enzyme) in DRG neurons but not in SGC. Pharmacological inhibition of aromatase caused apoptosis of CCI rat DRG neurons. Altogether, our results suggest that endogenously produced neurosteroids such as estradiol may be pivotal for the protection of DRG sensory neurons against sciatic nerve CCI-induced apoptosis.

  17. The contribution of Kv2.2-mediated currents decreases during the postnatal development of mouse dorsal root ganglion neurons.

    PubMed

    Regnier, Glenn; Bocksteins, Elke; Van de Vijver, Gerda; Snyders, Dirk J; van Bogaert, Pierre-Paul

    2016-03-01

    Delayed rectifier voltage-gated K(+)(Kv) channels play an important role in the regulation of the electrophysiological properties of neurons. In mouse dorsal root ganglion (DRG) neurons, a large fraction of the delayed rectifier current is carried by both homotetrameric Kv2 channels and heterotetrameric channels consisting of Kv2 and silent Kv (KvS) subunits (i.e., Kv5-Kv6 and Kv8-Kv9). However, little is known about the contribution of Kv2-mediated currents during the postnatal development ofDRGneurons. Here, we report that the Stromatoxin-1 (ScTx)-sensitive fraction of the total outward K(+)current (IK) from mouseDRGneurons gradually decreased (~13%,P < 0.05) during the first month of postnatal development. Because ScTx inhibits both Kv2.1- and Kv2.2-mediated currents, this gradual decrease may reflect a decrease in currents containing either subunit. However, the fraction of Kv2.1 antibody-sensitive current that only reflects the Kv2.1-mediated currents remained constant during that same period. These results suggested that the fractional contribution of Kv2.2-mediated currents relative toIKdecreased with postnatal age. SemiquantitativeRT-PCRanalysis indicated that this decrease can be attributed to developmental changes in Kv2.2 expression as themRNAlevels of the Kv2.2 subunit decreased gradually between 1 and 4 weeks of age. In addition, we observed age-dependent fluctuations in themRNAlevels of the Kv6.3, Kv8.1, Kv9.1, and Kv9.3 subunits. These results support an important role of both Kv2 and KvS subunits in the postnatal maturation ofDRGneurons.

  18. Oxaliplatin-Induced Peripheral Neuropathy via TRPA1 Stimulation in Mice Dorsal Root Ganglion Is Correlated with Aluminum Accumulation.

    PubMed

    Park, Jin-Hee; Chae, Jisook; Roh, Kangsan; Kil, Eui-Joon; Lee, Minji; Auh, Chung-Kyun; Lee, Myung-Ah; Yeom, Chang-Hwan; Lee, Sukchan

    2015-01-01

    Oxaliplatin is a platinum-based anticancer drug used to treat metastatic colorectal, breast, and lung cancers. While oxaliplatin kills cancer cells effectively, it exhibits several side effects of varying severity. Neuropathic pain is commonly experienced during treatment with oxaliplatin. Patients describe symptoms of paresthesias or dysesthesias that are triggered by cold (acute neuropathy), or as abnormal sensory or motor function (chronic neuropathy). In particular, we found that aluminum levels were relatively high in some cancer patients suffering from neuropathic pain based on clinical observations. Based on these findings, we hypothesized that aluminum accumulation in the dorsal root ganglion (DRG) in the course of oxaliplatin treatment exacerbates neuropathic pain. In mice injected with oxaliplatin (three cycles of 3 mg/kg i.p. daily for 5 days, followed by 5 days of rest), we detected cold allodynia using the acetone test, but not heat hyperalgesia using a hot plate. However, co-treatment with aluminum chloride (AlCl3∙6H2O; 7 mg/kg i.p. for 14 days: equivalent 0.78 mg/kg of elemental Al) and oxaliplatin (1 cycle of 3 mg/kg i.p. daily for 5 days, followed by 5 days of rest) synergistically induced cold allodynia as well as increased TRPAl mRNA and protein expression. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis showed a significant increase in aluminum concentrations in the DRG of mice treated with aluminum chloride and oxaliplatin compared to aluminum chloride alone. Similarly, in a mouse induced-tumor model, aluminum concentrations were increased in DRG tissue and tumor cells after oxaliplatin treatment. Taken together, these findings suggest that aluminum accumulation in the DRG may exacerbate neuropathic pain in oxaliplatin-treated mice.

  19. Reactive species modify NaV1.8 channels and affect action potentials in murine dorsal root ganglia neurons

    PubMed Central

    Schink, Martin; Leipolcf, Enrico; Schirmeyer, Jana; Schönherr, Roland; Hoshi, Toshinori; Heinemann, Stefan H.

    2016-01-01

    Dorsal root ganglia (DRG) neurons are important relay stations between the periphery and the central nervous system and are essential for somatosensory signaling. Reactive species are produced in a variety of physiological and pathophysiological conditions and are known to alter electric signaling. Here we studied the influence of reactive species on the electrical properties of DRG neurons from mice with the whole-cell patch-clamp method. Even mild stress induced by either low concentrations of chloramine-T (10 µM) or low-intensity blue-light irradiation profoundly diminished action potential frequency but prolonged single action potentials in wild-type neurons. The impact on evoked action potentials was much smaller in neurons deficient of the tetrodotoxin (TTX)-resistant voltage-gated sodium channel NaV1.8 (NaV1.8−/−), the channel most important for the action potential upstroke in DRG neurons. Low concentrations of chloramine-T caused a significant reduction of NaV1.8 peak current and at higher concentrations progressively slowed down inactivation. Blue light had a smaller effect on amplitude but slowed down NaV1.8 channel inactivation. The observed effects were less apparent for TTX-sensitive NaV channels. NaV1.8 is an important reactive-species-sensitive component in the electrical signaling of DRG neurons, potentially giving rise to loss-of-function and gain-of-function phenomena depending on the type of reactive species and their effective concentration and time of exposure. PMID:26383867

  20. 4α-phorbol 12,13-didecanoate activates cultured mouse dorsal root ganglia neurons independently of TRPV4

    PubMed Central

    Alexander, R; Kerby, A; Aubdool, AA; Power, AR; Grover, S; Gentry, C; Grant, AD

    2013-01-01

    Background and Purpose The Ca2+-permeable cation channel TRPV4 is activated by mechanical disturbance of the cell membrane and is implicated in mechanical hyperalgesia. Nerve growth factor (NGF) is increased during inflammation and causes mechanical hyperalgesia. 4α-phorbol 12,13-didecanoate (4αPDD) has been described as a selective TRPV4 agonist. We investigated NGF-induced hyperalgesia in TRPV4 wild-type (+/+) and knockout (–/–) mice, and the increases in [Ca2+]i produced by 4αPDD in cultured mouse dorsal root ganglia neurons following exposure to NGF. Experimental Approach Withdrawal thresholds to heat, von Frey hairs and pressure were measured in mice before and after systemic administration of NGF. Changes in intracellular Ca2+ concentration were measured by ratiometric imaging with Fura-2 in cultured DRG and trigeminal ganglia (TG) neurons during perfusion of TRPV4 agonists. Key Results Administration of NGF caused a significant sensitization to heat and von Frey stimuli in TRPV4 +/+ and –/– mice, but only TRPV4 +/+ mice showed sensitization to noxious pressure. 4αPDD stimulated a dose-dependent increase in [Ca2+]i in neurons from +/+ and –/– mice, with the proportion of responding neurons and magnitude of increase unaffected by the genotype. In contrast, the selective TRPV4 agonist GSK1016790A failed to stimulate an increase in intracellular Ca2+ in cultured neurons. Responses to 4αPDD were unaffected by pretreatment with NGF. Conclusions and Implications TRPV4 contributes to mechanosensation in vivo, but there is little evidence for functional TRPV4 in cultured DRG and TG neurons. We conclude that 4αPDD activates these neurons independently of TRPV4, so it is not appropriate to refer to 4αPDD as a selective TRPV4 agonist. PMID:22928864

  1. {alpha}7-nAChR-mediated suppression of hyperexcitability of colonic dorsal root ganglia neurons in experimental colitis.

    PubMed

    Abdrakhmanova, Galya R; AlSharari, Shakir; Kang, Minho; Damaj, M Imad; Akbarali, Hamid I

    2010-09-01

    Controlled clinical trials of nicotine transdermal patch for treatment of ulcerative colitis have been shown to improve histological and global clinical scores of colitis. Here we report that nicotine (1 microM) suppresses in vitro hyperexcitability of colonic dorsal root ganglia (DRG) (L(1)-L(2)) neurons in the dextran sodium sulfate (DSS)-induced mouse model of acute colonic inflammation. Nicotine gradually reduced regenerative multiple-spike action potentials in colitis mice to a single action potential. Nicotine's effect on hyperexcitability of inflamed neurons was blocked in the presence of an alpha(7)-nicotinic acetylcholine receptor (nAChR) antagonist, methyllicaconitine, while choline, the alpha(7)-nAChR agonist, induced a similar effect to that of nicotine. Consistent with these findings, nicotine failed to suppress hyperexcitability in colonic DRG neurons from DSS-treated alpha(7) knockout mice. Furthermore, colonic DRG neurons from DSS-treated alpha(7) knockout mice were characterized by lower rheobase (10 +/- 5 vs. 77 +/- 13 pA, respectively) and current threshold (28 +/- 4 vs. 103 +/- 8 pA, respectively) levels than DSS-treated C57BL/J6 mice. An interesting observation of this study is that 8 of 12 colonic DRG (L(1)-L(2)) neurons from control alpha(7) knockout mice exhibited multiple-spike action potential firing while no wild-type neurons did. Overall, our findings suggest that nicotine at low 1 microM concentration suppresses in vitro hyperexcitability of inflamed colonic DRG neurons in a mouse model of acute colonic inflammation via activation of alpha(7)-nAChRs.

  2. NERVE GROWTH FACTOR MAINTAINS POTASSIUM CONDUCTANCE AFTER NERVE INJURY IN ADULT CUTANEOUS AFFERENT DORSAL ROOT GANGLION NEURONS

    PubMed Central

    EVERILL, B.; KOCSIS, J. D.

    2008-01-01

    Whole-cell patch-clamp techniques were used to study the effects of nerve growth factor on voltage-dependent potassium conductance in normal and axotomized identified large cutaneous afferent dorsal root ganglion neurons (48–50 μm diameter) many of which probably give rise to myelinated Aβ fibers. K-currents were isolated by blocking Na- and Ca-currents with appropriate ion replacement and channel blockers. Separation of current components was achieved on the basis of response to variation in conditioning voltage. Cutaneous afferents were labeled by the retrograde marker hydroxy-stilbamide (FluoroGold) which was injected into the skin of the foot. The sciatic nerve was either ligated or crushed with fine forceps five to seven days later. Neurons were dissociated 14–17 days after injury. The cut ends of the sciatic nerves were positioned into polyethylene tubes, which were connected to mini-osmotic pumps filled with either nerve growth factor or sterile saline. Control neurons displayed a prominent sustained K-current and the transient potassium currents “A” and “D”. Nerve ligation, which blocks target reconnection resulted in near 50% reduction of total outward current; isolated sustained K-current and transient A-current were reduced by a comparable amount. Nerve crush, which allows regeneration to peripheral targets and exposure of the regenerating nerve to the distal nerve segment, resulted in a small reduction in sustained K-current but no reduction in transient A-current compared to controls. Levels of transient A-current and sustained K-current were maintained at control levels after nerve growth factor treatment. These results indicate that the large reduction in transient A-current, and in sustained K-current, observed in cutaneous afferent cell bodies after nerve ligation is prevented by application of nerve growth factor. PMID:11008179

  3. Thyroid hormone reduces the loss of axotomized sensory neurons in dorsal root ganglia after sciatic nerve transection in adult rat.

    PubMed

    Schenker, Michel; Kraftsik, Rudolf; Glauser, Liliane; Kuntzer, Thierry; Bogousslavsky, Julien; Barakat-Walter, Ibtissam

    2003-11-01

    We have shown that a local administration of thyroid hormones (T3) at the level of transected rat sciatic nerve induced a significant increase in the number of regenerated axons. To address the question of whether local administration of T3 rescues the axotomized sensory neurons from death, in the present study we estimated the total number of surviving neurons per dorsal root ganglion (DRG) in three experimental group animals. Forty-five days following rat sciatic nerve transection, the lumbar (L4 and L5) DRG were removed from PBS-control, T3-treated as well as from unoperated rats, and serial sections (1 microm) were cut. The physical dissector method was used to estimate the total number of sensory neurons in the DRGs. Our results revealed that in PBS-control rats transection of sciatic nerve leads to a significant (P < 0.001) decrease in the mean number of sensory neurons (8743.8 +/- 748.6) compared with the number of neurons in nontransected ganglion (mean 13,293.7 +/- 1368.4). However, administration of T3 immediately after sciatic nerve transection rescues a great number of axotomized neurons so that their mean neuron number (12,045.8 +/- 929.8) is not significantly different from the mean number of neurons in the nontransected ganglion. In addition, the volume of ganglia showed a similar tendency. These results suggest that T3 rescues a high number of axotomized sensory neurons from death and allows these cells to grow new axons. We believe that the relative preservation of neurons is important in considering future therapeutic approaches of human peripheral nerve lesion and sensory neuropathy.

  4. Small-molecule GSK-3 inhibitor rescued apoptosis and neurodegeneration in anesthetics-injured dorsal root ganglion neurons.

    PubMed

    Yu, Tianchao; Lin, Wanchun

    2016-12-01

    Application of general anesthetics may induce neurotoxicity in dorsal root ganglia (DRG) neurons. In this study, we examined the possible protective mechanism and associated signaling pathways of small-molecule glycogen synthase kinase-3 (GSK-3) inhibitor, SB216763, in bupivacaine-injured mouse DRG neurons in vitro. In vitro DRG explant of 6-week old mice was treated with 5mM bupivacaine to induce neurotoxicity. The explants were also pre-treated with SB216763 for 72h. Neural protection of SB216763 on bupivacaine-injured DRG neurons was investigated by TUNEL assay, neurite outgrowth assay and western blot assay, respectively. Possible downstream gene of GSK-3 signaling pathway, protein kinase C (PKC) was knocked down by siRNA in DRG explant. Its function in regulating GSK-3 inhibition induced DRG neural protection was also examined by TUNEL, neurite outgrowth and western blot assays. Pre-treatment of SB216763 significantly ameliorated bupivacaine induced apoptosis and neurite loss in DRG neurons. Western blot showed that, in addition to the decrease of phosphorylated-GSK-3 α/β protein, SB216763 increased PKC and decreased caspase-3 (Casp-3) in bupivacaine-injured DRG neurons. SiRNA-mediated PKC knockdown was able to reverse the neural protection of SB216763 in bupivacaine-injured DRG neurons. Western blot showed that PKC knockdown increased phosphorylated-GSK-3 α/β and Casp-3 protein in DRG neurons, confirming that PKC was directly involved in GSK-3-inhibition induced neural protection in DRG. GSK-3 inhibitor SB216763, through PKC, is effective in protecting anesthetics-induced neurotoxicity in DRG. Copyright © 2016. Published by Elsevier Masson SAS.

  5. The Effects of Target Skeletal Muscle Cells on Dorsal Root Ganglion Neuronal Outgrowth and Migration In Vitro

    PubMed Central

    Zhang, Weiwei; Li, Zhenzhong

    2013-01-01

    Targets of neuronal innervations play a vital role in regulating the survival and differentiation of innervating neurotrophin-responsive neurons. During development, neurons extend axons to their targets, and then their survival become dependent on the trophic substances secreted by their target cells. Sensory endings were present on myoblasts, myotubes, and myofibers in all intrafusal bundles regardless of age. The interdependence of sensory neurons and skeletal muscle (SKM) cells during both embryonic development and the maintenance of the mature functional state has not been fully understood. In the present study, neuromuscular cocultures of organotypic dorsal root ganglion (DRG) explants and dissociate SKM cells were established. Using this culture system, the morphological relationship between DRG neurons and SKM cells, neurites growth and neuronal migration were investigated. The migrating neurons were determined by fluorescent labeling of microtubule-associated protein-2 (MAP-2) and neurofilament 200 (NF-200) or growth-associated protein 43 (GAP-43). The expression of NF-200 and GAP-43 and their mRNAs was evaluated by Western blot assay and real time-PCR analysis. The results reveal that DRG explants showed more dense neurites outgrowth in neuromuscular cocultures as compared with that in the culture of DRG explants alone. The number of total migrating neurons (the MAP-2-expressing neurons) and the percentage NF-200-immunoreactive (IR) and GAP-43-IR neurons increased significantly in the presence of SKM cells. The levels of NF-200 and GAP-43 and their mRNAs increased significantly in neuromuscular cocultures as compared with that in the culture of DRG explants alone. These results suggested that target SKM cells play an important role in regulating neuronal protein synthesis, promoting neuritis outgrowth and neuronal migration of DRG explants in vitro. These results not only provide new clues for a better understanding of the association of SKM cells with

  6. Different types of spinal afferent nerve endings in stomach and esophagus identified by anterograde tracing from dorsal root ganglia.

    PubMed

    Spencer, Nick J; Kyloh, Melinda; Beckett, Elizabeth A; Brookes, Simon; Hibberd, Tim

    2016-10-15

    In visceral organs of mammals, most noxious (painful) stimuli as well as innocuous stimuli are detected by spinal afferent neurons, whose cell bodies lie in dorsal root ganglia (DRGs). One of the major unresolved questions is the location, morphology, and neurochemistry of the nerve endings of spinal afferents that actually detect these stimuli in the viscera. In the upper gastrointestinal (GI) tract, there have been many anterograde tracing studies of vagal afferent endings, but none on spinal afferent endings. Recently, we developed a technique that now provides selective labeling of only spinal afferents. We used this approach to identify spinal afferent nerve endings in the upper GI tract of mice. Animals were anesthetized, and injections of dextran-amine were made into thoracic DRGs (T8-T12). Seven days post surgery, mice were euthanized, and the stomach and esophagus were removed, fixed, and stained for calcitonin gene-related peptide (CGRP). Spinal afferent axons were identified that ramified extensively through many rows of myenteric ganglia and formed nerve endings in discrete anatomical layers. Most commonly, intraganglionic varicose endings (IGVEs) were identified in myenteric ganglia of the stomach and varicose simple-type endings in the circular muscle and mucosa. Less commonly, nerve endings were identified in internodal strands, blood vessels, submucosal ganglia, and longitudinal muscle. In the esophagus, only IGVEs were identified in myenteric ganglia. No intraganglionic lamellar endings (IGLEs) were identified in the stomach or esophagus. We present the first identification of spinal afferent endings in the upper GI tract. Eight distinct types of spinal afferent endings were identified in the stomach, and most of them were CGRP immunoreactive. J. Comp. Neurol. 524:3064-3083, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  7. Acid sensitivity of the spinal dorsal root ganglia C-fiber nociceptors innervating the guinea pig esophagus.

    PubMed

    Ru, F; Banovcin, P; Kollarik, M

    2015-06-01

    Gastroesophageal reflux can cause high acidity in the esophagus and trigger heartburn and pain. However, because of the esophageal mucosal barrier, the acidity at the nerve terminals of pain-mediating C-fibers in esophageal mucosa is predicted to be substantially lower. We hypothesized that the esophageal dorsal root ganglia (DRG) C-fibers are activated by mild acid (compared to acidic reflux), and express receptors and ion channels highly sensitive to acid. Extracellular single unit recordings of activity originating in esophageal DRG C-fiber nerve terminals were performed in the innervated esophagus preparation ex vivo. Acid was delivered in a manner that bypassed the esophageal mucosal barrier. The expression of mRNA for selected receptors in esophagus-specific DRG neurons was evaluated using single cell RT-PCR. Mild acid (pH = 6.5-5.5) activated esophageal DRG C-fibers in a pH-dependent manner. The response to mild acid at pH = 6 was not affected by the TRPV1 selective antagonist iodo-resiniferatoxin. The majority (70-95%) of esophageal DRG C-fiber neurons (TRPV1-positive) expressed mRNA for acid sensing ion channels (ASIC1a, ASIC1b, ASIC2b, and/or ASIC3), two-pore-domain (K2P) potassium channel TASK1, and the proton-sensing G-protein coupled receptor OGR1. Other evaluated targets (PKD2L1, TRPV4, TASK3, TALK1, G2A, GPR4, and TDAG8) were expressed rarely. Guinea pig esophageal DRG C-fibers are activated by mild acid via a TRPV1-independent mechanism, and express mRNA for several receptors and ion channels highly sensitive to acid. The high acid sensitivity of esophageal C-fibers may contribute to heartburn and pain in conditions of reduced mucosal barrier function. © 2015 John Wiley & Sons Ltd.

  8. Pyruvate Dehydrogenase Kinase-mediated Glycolytic Metabolic Shift in the Dorsal Root Ganglion Drives Painful Diabetic Neuropathy*

    PubMed Central

    Rahman, Md Habibur; Jha, Mithilesh Kumar; Kim, Jong-Heon; Nam, Youngpyo; Lee, Maan Gee; Go, Younghoon; Harris, Robert A.; Park, Dong Ho; Kook, Hyun; Lee, In-Kyu; Suk, Kyoungho

    2016-01-01

    The dorsal root ganglion (DRG) is a highly vulnerable site in diabetic neuropathy. Under diabetic conditions, the DRG is subjected to tissue ischemia or lower ambient oxygen tension that leads to aberrant metabolic functions. Metabolic dysfunctions have been documented to play a crucial role in the pathogenesis of diverse pain hypersensitivities. However, the contribution of diabetes-induced metabolic dysfunctions in the DRG to the pathogenesis of painful diabetic neuropathy remains ill-explored. In this study, we report that pyruvate dehydrogenase kinases (PDK2 and PDK4), key regulatory enzymes in glucose metabolism, mediate glycolytic metabolic shift in the DRG leading to painful diabetic neuropathy. Streptozotocin-induced diabetes substantially enhanced the expression and activity of the PDKs in the DRG, and the genetic ablation of Pdk2 and Pdk4 attenuated the hyperglycemia-induced pain hypersensitivity. Mechanistically, Pdk2/4 deficiency inhibited the diabetes-induced lactate surge, expression of pain-related ion channels, activation of satellite glial cells, and infiltration of macrophages in the DRG, in addition to reducing central sensitization and neuroinflammation hallmarks in the spinal cord, which probably accounts for the attenuated pain hypersensitivity. Pdk2/4-deficient mice were partly resistant to the diabetes-induced loss of peripheral nerve structure and function. Furthermore, in the experiments using DRG neuron cultures, lactic acid treatment enhanced the expression of the ion channels and compromised cell viability. Finally, the pharmacological inhibition of DRG PDKs or lactic acid production substantially attenuated diabetes-induced pain hypersensitivity. Taken together, PDK2/4 induction and the subsequent lactate surge induce the metabolic shift in the diabetic DRG, thereby contributing to the pathogenesis of painful diabetic neuropathy. PMID:26769971

  9. Quantitative Analysis of Rat Dorsal Root Ganglion Neurons Cultured on Microelectrode Arrays Based on Fluorescence Microscopy Image Processing.

    PubMed

    Mari, João Fernando; Saito, José Hiroki; Neves, Amanda Ferreira; Lotufo, Celina Monteiro da Cruz; Destro-Filho, João-Batista; Nicoletti, Maria do Carmo

    2015-12-01

    Microelectrode Arrays (MEA) are devices for long term electrophysiological recording of extracellular spontaneous or evocated activities on in vitro neuron culture. This work proposes and develops a framework for quantitative and morphological analysis of neuron cultures on MEAs, by processing their corresponding images, acquired by fluorescence microscopy. The neurons are segmented from the fluorescence channel images using a combination of segmentation by thresholding, watershed transform, and object classification. The positioning of microelectrodes is obtained from the transmitted light channel images using the circular Hough transform. The proposed method was applied to images of dissociated culture of rat dorsal root ganglion (DRG) neuronal cells. The morphological and topological quantitative analysis carried out produced information regarding the state of culture, such as population count, neuron-to-neuron and neuron-to-microelectrode distances, soma morphologies, neuron sizes, neuron and microelectrode spatial distributions. Most of the analysis of microscopy images taken from neuronal cultures on MEA only consider simple qualitative analysis. Also, the proposed framework aims to standardize the image processing and to compute quantitative useful measures for integrated image-signal studies and further computational simulations. As results show, the implemented microelectrode identification method is robust and so are the implemented neuron segmentation and classification one (with a correct segmentation rate up to 84%). The quantitative information retrieved by the method is highly relevant to assist the integrated signal-image study of recorded electrophysiological signals as well as the physical aspects of the neuron culture on MEA. Although the experiments deal with DRG cell images, cortical and hippocampal cell images could also be processed with small adjustments in the image processing parameter estimation.

  10. Vasodilatation in hyperalgesic rat skin evoked by stimulation of afferent A beta-fibers: further evidence for a role of dorsal root reflexes in allodynia.

    PubMed

    Garcia-Nicas, E; Laird, J M; Cervero, F

    2001-12-01

    In areas of secondary hyperalgesia, innocuous mechanical stimuli evoke pain (allodynia). We have proposed that this is produced by a central pre-synaptic interaction whereby A beta-fibers evoke spike activity (dorsal root reflexes) in nociceptive afferents (Pain, 68 (1996) 13). This activity should conduct centrally, evoking allodynia, and peripherally, evoking neurogenic vasodilatation. Here we tested this hypothesis by examining the effects of electrical stimulation of A beta-fibers on cutaneous blood flow before and after producing secondary hyperalgesia in anesthetized rats. Cutaneous blood flow was recorded in the hind paw skin innervated by the sural nerve using a laser Doppler flowmeter. The sural nerve was prepared for electrical stimulation, and the evoked activity was recorded from the sciatic nerve in continuity. Electrical stimulation (1 Hz, 4 x 0.2 ms pulses, 20 s) was applied to the sural nerve at 2T (A beta-fibers only) and 4T and 6T (A beta + A delta-fibers). Flux was recorded at baseline and after capsaicin or mustard oil application outside the sural nerve territory. The effects of intravenous administration of the calcitonin gene-related peptide (CGRP) receptor antagonist, alpha-CGRP(8-37), or of section of the sciatic nerve or of the L4-L6 dorsal roots were examined. Selective activation of the sural nerve A beta-fibers reliably evoked increases in cutaneous blood flow close to areas of chemical irritation or skin damage. A beta-fiber-evoked vasodilatation was abolished by sciatic nerve or dorsal root section and had a spatial arrangement and optimal stimulation pattern suggesting a central synaptic interaction similar to that responsible for dorsal root reflexes. The flux increases were dose-dependently and reversibly inhibited by alpha-CGRP(8-37), indicating that the A beta-fiber-evoked vasodilatation resulted from the antidromic activation of nociceptive cutaneous afferent fibers. These results support our hypothesis by showing activation of

  11. Functional profiles of SCN9A variants in dorsal root ganglion neurons and superior cervical ganglion neurons correlate with autonomic symptoms in small fibre neuropathy.

    PubMed

    Han, Chongyang; Hoeijmakers, Janneke G J; Liu, Shujun; Gerrits, Monique M; te Morsche, Rene H M; Lauria, Giuseppe; Dib-Hajj, Sulayman D; Drenth, Joost P H; Faber, Catharina G; Merkies, Ingemar S J; Waxman, Stephen G

    2012-09-01

    Patients with small fibre neuropathy typically manifest pain in distal extremities and severe autonomic dysfunction. However, occasionally patients present with minimal autonomic symptoms. The basis for this phenotypic difference is not understood. Sodium channel Na(v)1.7, encoded by the SCN9A gene, is preferentially expressed in the peripheral nervous system within sensory dorsal root ganglion and sympathetic ganglion neurons and their small diameter peripheral axons. We recently reported missense substitutions in SCN9A that encode functional Na(v)1.7 variants in 28% of patients with biopsy-confirmed small fibre neuropathy. Two patients with biopsy-confirmed small fibre neuropathy manifested minimal autonomic dysfunction unlike the other six patients in this series, and both of these patients carry the Na(v)1.7/R185H variant, presenting the opportunity to compare variants associated with extreme ends of a spectrum from minimal to severe autonomic dysfunction. Herein, we show by voltage-clamp that R185H variant channels enhance resurgent currents within dorsal root ganglion neurons and show by current-clamp that R185H renders dorsal root ganglion neurons hyperexcitable. We also show that in contrast, R185H variant channels do not produce detectable changes when studied by voltage-clamp within sympathetic neurons of the superior cervical ganglion, and have no effect on the excitability of these cells. As a comparator, we studied the Na(v)1.7 variant I739V, identified in three patients with small fibre neuropathy characterized by severe autonomic dysfunction as well as neuropathic pain, and show that this variant impairs channel slow inactivation within both dorsal root ganglion and superior cervical ganglion neurons, and renders dorsal root ganglion neurons hyperexcitable and superior cervical ganglion neurons hypoexcitable. Thus, we show that R185H, from patients with minimal autonomic dysfunction, does not produce detectable changes in the properties of

  12. The effects of gallamine on field and dorsal root potentials produced by antidromic stimulation of motor fibres in the frog spinal cord.

    PubMed

    Galindo, J; Rudomin, P

    1978-05-12

    The effects of gallamine on the intraspinal field potentials and the dorsal root potentials produced by antidromic stimulation of motor fibres were studied in the isolated frog spinal cord preparation. After gallamine (10-(3) M), the duration of the negative field potential produced by antidromic activation of motoneurons (N1 response) was increased often without changing its amplitude. This resulted in an increased passive spread of the antidromic action potential towards the dorsal dendritic regions, where afferent fibres terminate. In the untreated spinal cord, stimulation of motor axons produced a late negative dorsal root potential (VR-DRP) which was depressed after gallamine administration. Abolition of the VR-DRP was frequently associated with the appearance of a short latency, conducted response, in the dorsal roots (EVR-DRP). The earliest component of the EVR-DRP had a latency ranging between 0.5 and 2.5 ms measured after the peak of the N1 response recorded at the motor nucleus. Such a brief latency of the EVR-DRP suggests that this response results from electrical interaction between motoneurons and afferent fibres. After gallamine, the primary afferent depolarization produced by orthodromic stimulation of sensory nerves facilitates the EVR-DRP without necessarily increasing the amplitude or duration of the N1 response. Also, gallamine appears to increase directly the excitability of the afferent fibre terminal arborizations. The nature of the electrical interaction between motoneuron dendrites and afferent fibre terminal arborizations is discussed in terms of two hypotheses: interaction by current flows and by electrical coupling.

  13. Pregabalin alters nociceptive behavior and expression level of P2X3 receptor in the spinal dorsal horn in a rat model induced by chronic compression of the dorsal root ganglion.

    PubMed

    Yu, Jianfeng; Fu, Peng; Zhang, Yan; Liu, Shuzhen; Cui, Donghong

    2013-12-01

    P2X3 receptors are present in the spinal dorsal horn (SDH) and play an essential role in the regulation of nociception and pain. Pregabalin (PGB) has been used as a new antiepileptic drug in the treatment of neuropathic pain. However, it is unclear whether PGB-induced analgesia was associated with the P2X3 receptor in SDH. Here, rats were randomly divided into four groups (n = 12 per group), including 2 sham operation groups, which was treated by normal saline (Sham + NS group) or PGB (Sham + PGB group), other 2 groups with chronic compression of the dorsal root ganglion, a normal saline-treated CCD group (CCD+NS group), and a PGB-treated CCD group (CCD + PGB group). A rat model of neuropathic pain was used by compressing the right L4 and L5 dorsal root ganglia. Each group was evaluated using the mechanical withdrawal threshold (MWT). The mRNA and protein levels of the P2X3 receptor in the ipsilateral SDH were measured by RT-PCR, western blot, and immunofluorescence on 14 day after CCD operation. CCD rats showed the highest mechanical hyperalgesia and the lowest pain threshold in the four groups. Simultaneously, CCD rats showed higher P2X3 mRNA and protein expression in ipsilateral side of the SDH than the sham operation rats. However, the MWT was increased and expression of P2X3 mRNA and protein in the ipsilateral SDH in CCD rats was decreased 3 days after PGB treatment. Thus, PGB may partially reverse mechanical hyperalgesia in CCD rats by inhibiting P2X3 receptor expression in the ipsilateral SDH.

  14. Hyperexcitability in Spinal WDR Neurons following Experimental Disc Herniation Is Associated with Upregulation of Fractalkine and Its Receptor in Nucleus Pulposus and the Dorsal Root Ganglion

    PubMed Central

    Moen, Aurora; Haugen, Fred; Gjerstad, Johannes

    2016-01-01

    Introduction. Lumbar radicular pain following intervertebral disc herniation may be associated with a local inflammatory response induced by nucleus pulposus (NP) cells. Methods. In anaesthetized Lewis rats, extracellular single unit recordings of wide dynamic range (WDR) neurons in the dorsal horn and qPCR were used to explore the effect of NP application onto the dorsal nerve roots (L3–L5). Results. A clear increase in C-fiber response was observed following NP conditioning. In the NP tissue, the expression of interleukin-1β (IL-1β), colony stimulating factor 1 (Csf1), fractalkine (CX3CL1), and the fractalkine receptor CX3CR1 was increased. Minocycline, an inhibitor of microglial activation, inhibited the increase in neuronal activity and attenuated the increase in IL-1β, Csf1, CX3L1, and CX3CR1 expression in NP tissue. In addition, the results demonstrated an increase in the expression of TNF, CX3CL1, and CX3CR1 in the dorsal root ganglions (DRGs). Conclusion. Hyperexcitability in the pain pathways and the local inflammation after disc herniation may involve upregulation of CX3CL1 signaling in both the NP and the DRG. PMID:28116212

  15. [Biomechanical characteristics of spinal cord tissue--basis for the development of modifications of the DREZ (dorsal root entry zone) operation].

    PubMed

    Spaić, M; Mikicić, D; Ilić, S; Milosavljević, I; Ivanović, S; Slavik, E; Antić, B

    2004-01-01

    Mechanical properties of the spinal cord tissue--biological basis for the development of the modality of the DREZ surgery lesioning technique Succesful treatment of the chronic neurogenic pain of spinal cord and cauda equina injury origin remains a significant management problem. The mechanism of this pain phenomenon has been shown to be related to neurochemical changes that lead to the state of hypereactivity of the second order dorsal horn neurons. The DREZ surgery (Dorsal Root Entry Zone lesion), designed to destroy anatomy structures involved in pain generating thus interrupting the neurogenic pain mechanism, as a causative procedure in treating this chronic pain, has been performed by using different technical modalities: Radiofrequency (RF) coagulation technic, Laser, Ultrasound and Microsurgical DREZotomy technic. The purpose of the study was to assess the possibility for the establishment of the lesioning technic based on the natural difference in the mechanical properties between the white and gray cord substance. We experimentally deteminated mechanical properties of the human cadaveric cord white versus gray tissue for the purpose of testing possibility of selective suction of the dorsal horn gray substance as a DREZ lesioning procedure. Based on the fact of the difference in tissue elasticity between white and gray cord substance we established a new and simple DREZ surgical lesioning technique that was tested on cadaver cord. For the purpose of testing and comparing the size and shape of the DREZ lesion axchieved the DREZ surgery has been performed on cadaver cord by employing selective dorsal horn suction as a lesioning method. After the procedure cadaver cord underwent histological fixation and analysis of the DREZ lesions achieved. Our result revealed that the white cord substance with longitudinal fiber structure had four time higher dynamical viscosity than gray substance of local neuronal network structure (150 PaS versus 37.5 PaS) that provided

  16. A computational model for estimating recruitment of primary afferent fibers by intraneural stimulation in the dorsal root ganglia

    NASA Astrophysics Data System (ADS)

    Bourbeau, D. J.; Hokanson, J. A.; Rubin, J. E.; Weber, D. J.

    2011-10-01

    Primary afferent microstimulation has been proposed as a method for activating cutaneous and muscle afferent fibers to restore tactile and proprioceptive feedback after limb loss or peripheral neuropathy. Large populations of primary afferent fibers can be accessed directly by implanting microelectrode arrays in the dorsal root ganglia (DRG), which provide a compact and stable target for stimulating a diverse group of sensory fibers. To gain insight into factors affecting the number and types of primary afferents activated, we developed a computational model that simulates the recruitment of fibers in the feline L7 DRG. The model comprises two parts. The first part is a single-fiber model used to describe the current-distance relation and was based on the McIntyre-Richardson-Grill model for excitability. The second part uses the results of the singe-fiber model and published data on fiber size distributions to predict the probability of recruiting a given number of fibers as a function of stimulus intensity. The range of intensities over which exactly one fiber was recruited was approximately 0.5-5 µA (0.1-1 nC per phase); the stimulus intensity at which the probability of recruiting exactly one fiber was maximized was 2.3 µA. However, at 2.3 µA, it was also possible to recruit up to three fibers, albeit with a lower probability. Stimulation amplitudes up to 6 µA were tested with the population model, which showed that as the amplitude increased, the number of fibers recruited increased exponentially. The distribution of threshold amplitudes predicted by the model was similar to that previously reported by in vivo experimentation. Finally, the model suggested that medium diameter fibers (7.3-11.5 µm) may be recruited with much greater probability than large diameter fibers (12.8-16 µm). This model may be used to efficiently test a range of stimulation parameters and nerve morphologies to complement results from electrophysiology experiments and to aid in the

  17. Kv4 Channels Underlie the Subthreshold-Operating A-type K-current in Nociceptive Dorsal Root Ganglion Neurons.

    PubMed

    Phuket, Thanawath Ratanadilok Na; Covarrubias, Manuel

    2009-01-01

    The dorsal root ganglion (DRG) contains heterogeneous populations of sensory neurons including primary nociceptive neurons and C-fibers implicated in pain signaling. Recent studies have demonstrated DRG hyperexcitability associated with downregulation of A-type K(+) channels; however, the molecular correlate of the corresponding A-type K(+) current (I(A)) has remained hypothetical. Kv4 channels may underlie the I(A) in DRG neurons. We combined electrophysiology, molecular biology (Whole-Tissue and Single-Cell RT-PCR) and immunohistochemistry to investigate the molecular basis of the I(A) in acutely dissociated DRG neurons from 7- to 8-day-old rats. Whole-cell recordings demonstrate a robust tetraethylammonium-resistant (20 mM) and 4-aminopyridine-sensitive (5 mM) I(A). Matching Kv4 channel properties, activation and inactivation of this I(A) occur in the subthreshold range of membrane potentials and the rate of recovery from inactivation is rapid and voltage-dependent. Among Kv4 transcripts, the DRG expresses significant levels of Kv4.1 and Kv4.3 mRNAs. Also, single small-medium diameter DRG neurons ( approximately 30 mum) exhibit correlated frequent expression of mRNAs encoding Kv4.1 and Nav1.8, a known nociceptor marker. In contrast, the expressions of Kv1.4 and Kv4.2 mRNAs at the whole-tissue and single-cell levels are relatively low and infrequent. Kv4 protein expression in nociceptive DRG neurons was confirmed by immunohistochemistry, which demonstrates colocalization of Kv4.3 and Nav1.8, and negligible expression of Kv4.2. Furthermore, specific dominant-negative suppression and overexpression strategies confirmed the contribution of Kv4 channels to I(A) in DRG neurons. Contrasting the expression patterns of Kv4 channels in the central and peripheral nervous systems, we discuss possible functional roles of these channels in primary sensory neurons.

  18. Action potential propagation through embryonic dorsal root ganglion cells in culture. II. Decrease of conduction reliability during repetitive stimulation.

    PubMed

    Lüscher, C; Streit, J; Lipp, P; Lüscher, H R

    1994-08-01

    1. The reliability of the propagation of action potentials (AP) through dorsal root ganglion (DRG) cells in embryonic slice cultures was investigated during repetitive stimulation at 1-20 Hz. Membrane potentials of DRG cells were recorded intracellularly while the axons were stimulated by an extracellular electrode. 2. In analogy to the double-pulse experiments reported previously, either one or two types of propagation failures were recorded during repetitive stimulation, depending on the cell morphology. In contrast to the double-pulse experiments, the failures appeared at longer interpulse intervals and usually only after several tens of stimuli with reliable propagation. 3. In the period with reliable propagation before the failures, a decrease in the conduction velocity and in the amplitude of the afterhyperpolarization (AHP), an increase in the total membrane conductance, and the disappearance of the action potential "shoulder" were observed. 4. The reliability of conduction during repetitive stimulation was improved by lowering the extracellular calcium concentration or by replacing the extracellular calcium by strontium. The reliability of conduction decreased by the application of cadmium, a calcium channel blocker, 4-amino pyridine, a fast potassium channel blocker, or apamin or muscarine, the blockers of calcium-dependent potassium channels. The reliability of conduction was not effected by blocking the sodium potassium pump with ouabain or by replacing extracellular sodium with lithium. 5. In the period with reliable propagation cadmium, apamin, and muscarine reduced the amplitude of the AHP. The shoulder of the action potential was more pronounced and not sensitive to repetitive stimulation when extracellular calcium was replaced by strontium. It disappeared when cadmium was applied. 6. In DRG somata changes of the intracellular Ca2+ concentration were monitored by measuring the fluorescence of the Ca2+ indicator Fluo-3 with a laser-scanning confocal

  19. Expression and properties of hyperpolarization-activated current in rat dorsal root ganglion neurons with known sensory function

    PubMed Central

    Gao, L L; McMullan, S; Djouhri, L; Acosta, C; Harper, A A; Lawson, S N

    2012-01-01

    The hyperpolarization-activated current (Ih) has been implicated in nociception/pain, but its expression levels in nociceptors remained unknown. We recorded Ih magnitude and properties by voltage clamp from dorsal root ganglion (DRG) neurons in vivo, after classifying them as nociceptive or low-threshold-mechanoreceptors (LTMs) and as having C-, Aδ- or Aα/β-conduction velocities (CVs). For both nociceptors and LTMs, Ih amplitude and Ih density (at −100 mV) were significantly positively correlated with CV. Median Ih magnitudes and Ih density in neuronal subgroups were respectively: muscle spindle afferents (MSAs): −4.6 nA, −33 pA pF−1; cutaneous Aα/β LTMs: −2.2 nA, −20 pA pF−1; Aβ-nociceptors: −2.6 nA, −21 pA pF−1; both Aδ-LTMs and nociceptors: −1.3 nA, ∼−14 pA pF−1; C-LTMs: −0.4 nA, −7.6 pA pF−1; and C-nociceptors: −0.26 nA, −5 pA pF−1. Ih activation slow time constants (slow τ values) were strongly correlated with fast τ values; both were shortest in MSAs. Most neurons had τ values consistent with HCN1-related Ih; others had τ values closer to HCN1+HCN2 channels, or HCN2 in the presence of cAMP. In contrast, median half-activation voltages (V0.5) of −80 to −86 mV for neuronal subgroups suggest contributions of HCN2 to Ih. τ values were unrelated to CV but were inversely correlated with Ih and Ih density for all non-MSA LTMs, and for Aδ-nociceptors. From activation curves ∼2–7% of Ih would be activated at normal membrane potentials. The high Ih may be important for excitability of A-nociceptors (responsible for sharp/pricking-type pain) and Aα/β-LTMs (tactile sensations and proprioception). Underlying HCN expression in these subgroups therefore needs to be determined. Altered Ih expression and/or properties (e.g. in chronic/pathological pain states) may influence both nociceptor and LTM excitability. PMID:22753545

  20. α-Conotoxin Vc1.1 inhibits human dorsal root ganglion neuroexcitability and mouse colonic nociception via GABAB receptors.

    PubMed

    Castro, Joel; Harrington, Andrea M; Garcia-Caraballo, Sonia; Maddern, Jessica; Grundy, Luke; Zhang, Jingming; Page, Guy; Miller, Paul E; Craik, David J; Adams, David J; Brierley, Stuart M

    2017-06-01

    α-Conotoxin Vc1.1 is a small disulfide-bonded peptide from the venom of the marine cone snail Conus victoriae. Vc1.1 has antinociceptive actions in animal models of neuropathic pain, but its applicability to inhibiting human dorsal root ganglion (DRG) neuroexcitability and reducing chronic visceral pain (CVP) is unknown. We determined the inhibitory actions of Vc1.1 on human DRG neurons and on mouse colonic sensory afferents in healthy and chronic visceral hypersensitivity (CVH) states. In mice, visceral nociception was assessed by neuronal activation within the spinal cord in response to noxious colorectal distension (CRD). Quantitative-reverse-transcription-PCR, single-cell-reverse-transcription-PCR and immunohistochemistry determined γ-aminobutyric acid receptor B (GABABR) and voltage-gated calcium channel (CaV2.2, CaV2.3) expression in human and mouse DRG neurons. Vc1.1 reduced the excitability of human DRG neurons, whereas a synthetic Vc1.1 analogue that is inactive at GABABR did not. Human DRG neurons expressed GABABR and its downstream effector channels CaV2.2 and CaV2.3. Mouse colonic DRG neurons exhibited high GABABR, CaV2.2 and CaV2.3 expression, with upregulation of the CaV2.2 exon-37a variant during CVH. Vc1.1 inhibited mouse colonic afferents ex vivo and nociceptive signalling of noxious CRD into the spinal cord in vivo, with greatest efficacy observed during CVH. A selective GABABR antagonist prevented Vc1.1-induced inhibition, whereas blocking both CaV2.2 and CaV2.3 caused inhibition comparable with Vc1.1 alone. Vc1.1-mediated activation of GABABR is a novel mechanism for reducing the excitability of human DRG neurons. Vc1.1-induced activation of GABABR on the peripheral endings of colonic afferents reduces nociceptive signalling. The enhanced antinociceptive actions of Vc1.1 during CVH suggest it is a novel candidate for the treatment for CVP. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a

  1. Voltage-dependent calcium currents are enhanced in dorsal root ganglion neurones from the Bio Bred/Worchester diabetic rat.

    PubMed Central

    Hall, K E; Sima, A A; Wiley, J W

    1995-01-01

    1. Whole-cell, high-threshold, voltage-dependent calcium currents (ICa) were enhanced in acutely dissociated, capsaicin-sensitive dorsal root ganglion neurones from diabetic Bio Bred/Worchester (BB/W) rats, compared with those from age-matched, non-diabetic controls. The magnitude of the enhancement increased with the duration of diabetes, and reached significance at diabetic durations of 6 months (diabetic: 6.3 +/- 0.4 nA; current density (CD), 157 +/- 12 pA pF-1; means +/- S.E.M., n = 9, P < 0.01; control: 3.9 +/- 0.6 nA; CD, 116 +/- 11 pA pF-1; n = 18) and 8 months (diabetic: 7.6 +/- 0.4 nA; CD, 177 +/- 25 pA pF-1; n = 11, P < 0.005; control: 5.1 +/- 0.5 nA; CD, 111 +/- 26 pA pF-1; n = 15). Low-threshold, voltage-dependent ICa were also enhanced in neurones from animals diabetic for 8 months (diabetic: 2.5 +/- 0.7 nA, n = 4, P < 0.05; control: 0.7 +/- 0.5 nA, n = 6). 2. The ICa enhancement was prevented by long-term treatment of diabetic animals with an aldose reductase inhibitor (ARI; peak ICa at 6 months: 4.41 +/- 0.48 nA, n = 2; at 8 months: 4.32 +/- 0.60 nA, n = 9). 3. The ICa enhancement was not due to a shift in the voltage dependence of either the current-voltage relationship or steady-state inactivation. 4. The L channel antagonist nifedipine and preferential N channel antagonist omega-conotoxin GVIA (omega-CgTX) caused a greater inhibition of high-threshold ICa in diabetic neurones compared with controls (nifedipine: control: 25 +/- 3%, n = 26; diabetic: 36 +/- 7%, n = 11; omega-CgTX: control: 40 +/- 4%, n = 21; diabetic: 50 +/- 7%, n = 7). Diabetic neurones also demonstrated a significantly greater residual current (2.44 +/- 0.34 nA, n = 7) in the presence of both antagonists vs. controls (1.28 +/- 0.30 nA, n = 8, P < 0.05), suggesting that N-, L- and additional non-N-, non-L-type high-threshold ICa were enhanced. Images Figure 2 PMID:7473199

  2. Augmented P2X response and immunolabeling in dorsal root ganglion neurons innervating skeletal muscle following femoral artery occlusion.

    PubMed

    Xing, Jihong; Lu, Jian; Li, Jianhua

    2013-04-01

    The responsiveness of sensory neurons to muscle metabolites is altered under the conditions of insufficient limb blood supply in some diseases, such as peripheral artery disease. The purpose of this study was to examine ATP-induced current with activation of purinergic P2X subtypes P2X₃ and P2X₂/₃ in dorsal root ganglion (DRG) neurons of control limbs and limbs with 24 h of femoral artery occlusion using whole cell patch-clamp methods. Also, dual-labeling immunohistochemistry was employed to determine existence of P2X₃ expression in DRG neurons of thin-fiber afferents. DRG neurons from 4- to 6-wk-old rats were labeled by injecting the fluorescence tracer DiI into the hindlimb muscles 4-5 days before the recording experiments. Transient (P2X₃), mixed (P2X₃ and P2X₂/₃), and sustained (P2X₂/₃) current responses to α,β-methylene ATP (a P2X receptor agonist) are observed in small and medium DRG neurons, and size distribution of DRG neurons is similar in control and occluded limbs. However, the peak current amplitude of DRG neuron induced by stimulation of P2X₃ and/or P2X₂/₃ is larger in occluded limbs than that in control limbs. Moreover, the percentage of DRG neurons with P2X₃ transient currents is greater after arterial occlusion compared with control. In addition, a rapid desensitization was observed in DRG neurons with transient currents, but not with sustained currents in control and occluded groups. Furthermore, results from immunofluorescence experiments show that femoral artery occlusion primarily augments P2X₃ expression within DRG neurons projecting C-fiber afferents. Overall, these findings suggest that 1) greater ATP-induced currents with activation of P2X₃ and P2X₂/₃ are developed when hindlimb arterial blood supply is deficient under ischemic conditions and 2) increased P2X₃ expression is largely observed in C-fibers of DRG neurons after hindlimb vascular insufficiency.

  3. Effects of sodium bisulfite with or without procaine derivatives on axons of cultured mouse dorsal root ganglion neurons.

    PubMed

    Takenami, Tamie; Hiruma, Hiromi; Kaneko, Haruka; Okamoto, Hirotsugu; Kawakami, Tadashi

    2015-01-01

    Sodium bisulfite (NaHSO3) was clinically used as a preservative agent for local anesthetics but was later suspected to be neurotoxic. However, recent studies reported that NaHSO3 reduces the neurotoxicity of local anesthetics. The purpose of this study was to examine the effects of NaHSO3 with and without procaine on axonal transport in cultured mouse dorsal root ganglion (DRG) neurons. Experiment 1 served to determine the dose-dependent effects of NaHSO3 on axonal transport (DRG neurons were treated with 0.01, 0.1, 1, 10, or 20 mM of NaHSO3), whereas experiment 2 investigated the effect of 0.1 mM NaHSO3 on the action of local anesthetics on axonal transport (DRG neurons were treated with 1 mM procaine alone, or with 0.1 mM NaHSO3 plus 1 mM procaine). As an additional experiment, DRG neurons were also treated with 1 mM chloroprocaine alone, or with 0.1 mM NaHSO3 plus 1 mM chloroprocaine. In these experiments, we analyzed the percent change in the number of anterogradely and retrogradely transported organelles and recorded changes in neurite morphology using video-enhanced microscopy. In experiment 1, NaHSO3 at more than 1 mM caused cell membrane damage and complete inhibition of axonal transport, whereas 0.1 mM NaHSO3 maintained axonal transport at 40% to 60% of control with intact cell membrane. In experiment 2, 1 mM procaine alone maintained axonal transport at 90% to 100%. However, application of 1 mM procaine-0.1 mM NaHSO3 solution resulted in deformation of neurites and with complete cessation of axonal transport. Likewise, although 1 mM chloroprocaine maintain axonal transport at 80% to 100%, 1 mM chloroprocaine-0.1 mM NaHSO3 arrested axonal transport. NaHSO3 resulted in a dose-dependent damage to the cell membrane and axonal transport, especially when used in combination with procaine or chloroprocaine.

  4. Kv3 channels contribute to the delayed rectifier current in small cultured mouse dorsal root ganglion neurons.

    PubMed

    Bocksteins, Elke; Van de Vijver, Gerda; Van Bogaert, Pierre-Paul; Snyders, Dirk J

    2012-08-15

    Delayed rectifier voltage-gated K(+) (K(V)) channels are important determinants of neuronal excitability. However, the large number of K(V) subunits poses a major challenge to establish the molecular composition of the native neuronal K(+) currents. A large part (∼60%) of the delayed rectifier current (I(K)) in small mouse dorsal root ganglion (DRG) neurons has been shown to be carried by both homotetrameric K(V)2.1 and heterotetrameric channels of K(V)2 subunits with silent K(V) subunits (K(V)S), while a contribution of K(V)1 channels has also been demonstrated. Because K(V)3 subunits also generate delayed rectifier currents, we investigated the contribution of K(V)3 subunits to I(K) in small mouse DRG neurons. After stromatoxin (ScTx) pretreatment to block the K(V)2-containing component, application of 1 mM TEA caused significant additional block, indicating that the ScTx-insensitive part of I(K) could include K(V)1, K(V)3, and/or M-current channels (KCNQ2/3). Combining ScTx and dendrotoxin confirmed a relevant contribution of K(V)2 and K(V)2/K(V)S, and K(V)1 subunits to I(K) in small mouse DRG neurons. After application of these toxins, a significant TEA-sensitive current (∼19% of total I(K)) remained with biophysical properties that corresponded to those of K(V)3 currents obtained in expression systems. Using RT-PCR, we detected K(V)3.1-3 mRNA in DRG neurons. Furthermore, Western blot and immunocytochemistry using K(V)3.1-specific antibodies confirmed the presence of K(V)3.1 in cultured DRG neurons. These biophysical, pharmacological, and molecular results demonstrate a relevant contribution (∼19%) of K(V)3-containing channels to I(K) in small mouse DRG neurons, supporting a substantial role for K(V)3 subunits in these neurons.

  5. Isoquercetin ameliorates tunicamycin-induced apoptosis in rat dorsal root ganglion neurons via suppressing ROS-dependent endoplasmic reticulum stress.

    PubMed

    Lu, Tan; Zhang, Chao; Chai, Mingxiang; An, Yongbo

    2016-05-01

    Recent studies showed that Isoquercetin (Iso), a novel extracts of plants and fruits could protect neuronal cells from neurotoxicity and neuro-inflammation. However, its role in acute spinal cord injury (ASCI) have not been elucidated. In the present study, we investigated whether Iso could prevent Tunicamycin (TUN)-induced rat dorsal root ganglion (DRG) neurons from apoptosis and endoplasmic reticulum (ER) stress. DRG neurons were pre-treated with different doses of Iso for 24h (h) and then were stimulated with TUN (0.75μg/ml) for 24h. The cytotoxic effects and apoptosis were detected by MTT assay and TUNEL staining. The protein and mRNA expression levels were detected by Real Time PCR and Western blot, respectively. The localization of cleaved caspase-12 was evaluated by immunofluorescent staining and Western blot. The activation of caspase were measured by colorimetric assays and Western blot. Lactate Dehydrogenase (LDH) and Malondialdehyde (MDA) leakage were detected by the LDH or MDA Detection Kit PLUS. Iso protected TUN-associated DRG neurons from being damaged by cytotoxicity and apoptosis in a dose-dependent manner. Increased LDH and MDA leakage and proportion of TUNEL-positive cells, activation of caspase-3 and -9, increased Bcl-2 Assaciated X protein (Bax)/B cell lymphoma/lewkmia-2 (Bcl-2) ratio and mRNA levels of p53 Upregulated Modulator Of Apoptosis (PUMA) and DP5, and mitochondrial Cytochrome c release. Additionally, Iso down-regulated mRNA levels of ER stress genes, such as glucose-regulated protein 78 (GRP78), GRP94, C/EBP homologous protein (CHOP), and cleaved caspase-12 in TUN-induced DRG neurons. Moreover, Iso blocked the activation of three key branches of unfolded protein response in DRG neurons, including phosphorylation of pancreatic ER stress kinase (PERK), eukaryotic initiation factor 2 alpha (eIF2α), inositol-requiring enzyme 1α (IRE1α), and transcription factor 6 (ATF6). Collectively, Iso prevented TUN-induced DRG neurons apoptosis by

  6. Activation of TRPC channels contributes to OA-NO2-induced responses in guinea-pig dorsal root ganglion neurons

    PubMed Central

    Zhang, Xiulin; Beckel, Jonathan M; Daugherty, Stephanie L; Wang, Ting; Woodcock, Stephen R; Freeman, Bruce A; de Groat, William C

    2014-01-01

    Effects of nitro-oleic acid (OA-NO2) on TRP channels were examined in guinea-pig dissociated dorsal root ganglia (DRG) neurons using calcium imaging and patch clamp techniques. OA-NO2 increased intracellular Ca2+ in 60–80% DRG neurons. 1-Oleoyl-2acetyl-sn-glycerol (OAG), a TRPC agonist, elicited responses in 36% of OA-NO2-sensitive neurons while capsaicin (TRPV1 agonist) or allyl-isothiocyanate (AITC, TRPA1 agonist) elicited responses in only 16% and 10%, respectively, of these neurons. A TRPV1 antagonist (diarylpiperazine, 5 μm) in combination with a TRPA1 antagonist (HC-030031, 30 μm) did not change the amplitude of the Ca2+ transients or percentage of neurons responding to OA-NO2; however, a reducing agent DTT (50 mm) or La3+ (50 μm) completely abolished OA-NO2 responses. OA-NO2 also induced a transient inward current associated with a membrane depolarization followed by a prolonged outward current and hyperpolarization in 80% of neurons. The reversal potentials of inward and outward currents were approximately −20 mV and −60 mV, respectively. Inward current was reduced when extracellular Na+ was absent, but unchanged by niflumic acid (100 μm), a Cl− channel blocker. Outward current was abolished in the absence of extracellular Ca2+ or a combination of two Ca2+-activated K+ channel blockers (iberiotoxin, 100 nm and apamin, 1 μm). BTP2 (1 or 10 μm), a broad spectrum TRPC antagonist, or La3+ (50 μm) completely abolished OA-NO2 currents. RT-PCR performed on mRNA extracted from DRGs revealed the expression of all seven subtypes of TRPC channels. These results support the hypothesis that OA-NO2 activates TRPC channels other than the TRPV1 and TRPA1 channels already known to be targets in rat and mouse sensory neurons and challenge the prevailing view that electrophilic compounds act specifically on TRPA1 or TRPV1 channels. The modulation of sensory neuron excitability via actions on multiple TRP channels can contribute to the anti-inflammatory effect

  7. The effects of inflammation on glial fibrillary acidic protein expression in satellite cells of the dorsal root ganglion.

    PubMed

    Siemionow, Krzysztof; Klimczak, Aleksandra; Brzezicki, Grzegorz; Siemionow, Maria; McLain, Robert F

    2009-07-15

    After undergoing L5 hemilaminectomy, chromic gut suture was placed onto the DRG and the animals were sacrificed at various time-points. The purpose of this study was to identify the effects of inflammation on satellite cells (SCs) of the dorsal root ganglion (DRG) by analyzing glial fibrillary acidic protein (GFAP) expression in of the DRG at various time points. SCs are neuroglial cells that closely interact with nerve cells of the DRG. The role of SC remains unknown GFAP expression increases in response to CNS injury. Loss of GFAP has impaired Schwann cell proliferation and delayed nerve regeneration after injury. Sixty rats underwent a left L5 hemilaminectomy. In Group I, a chromic-gut suture was place topically on the DRG (n = 30), Group II was the sham surgery group (n = 30). DRGs were harvested at 6, 24, 48, 72 hours, and 7 days after surgery. In Group III, 6 control rats were killed and their bilateral L5 DRG harvested. The harvested DRG were analyzed using light microscopy for SC immunoreactivity, using GFAP, HIS-36, TNF-alpha, IL-1alpha, IL-1beta, IL-6 monoclonal antibodies. One hundred thirty-two DRGs were harvested for analysis. Naïve controls and neurons did not express GFAP. The SC sheath expressed GFAP as early as 6 hours postchromic gut application. In Group I, GFAP expression steadily increased after chromic-gut application with 100% of SC soma and SC sheaths being GFAP positive at 7 days. The contralateral DRG demonstrated delayed GFAP expression, with 83% of SC soma and SC sheaths were GFAP positive at 7 days. In Group II, 89% of sacs expressed GFAP by 7 compared to 79% in the contralateral undisturbed DRG. Under physiologic conditions, the expression of GFAP by SCs is undetectable. As the inflammatory process develops, GFAP expression steadily increases with 100% of SCs being GFAP immunoreactive 7 days after chromic gut application. These data suggest that SCs are the primary source of GFAP in the DRG. We hypothesize that SC play an important

  8. Opioid-induced hypernociception is associated with hyperexcitability and altered tetrodotoxin-resistant Na+ channel function of dorsal root ganglia

    PubMed Central

    Ross, Gracious R.; Gade, Aravind R.; Dewey, William L.

    2012-01-01

    Opiates are potent analgesics for moderate to severe pain. Paradoxically, patients under chronic opiates have reported hypernociception, the mechanisms of which are unknown. Using standard patch-clamp technique, we examined the excitability, biophysical properties of tetrodotoxin-resistant (TTX-R) Na+ and transient receptor potential vanilloid 1 (TRPV1) channels of dorsal root ganglia neurons (DRG) (L5–S1) from mice pelleted with morphine (75 mg) or placebo (7 days). Hypernociception was confirmed by acetic acid-writhing test following 7-day morphine. Chronic morphine enhanced the neuronal excitability, since the rheobase for action potential (AP) firing was significantly (P < 0.01) lower (38 ± 7 vs. 100 ± 15 pA) while the number of APs at 2× rheobase was higher (4.4 ± 0.8 vs. 2 ± 0.5) than placebo (n = 13–20). The potential of half-maximum activation (V1/2) of TTX-R Na+ currents was shifted to more hyperpolarized potential in the chronic morphine group (−37 ± 1 mV) vs. placebo (−28 ± 1 mV) without altering the V1/2 of inactivation (−41 ± 1 vs. −33 ± 1 mV) (n = 8–11). Recovery rate from inactivation of TTX-R Na+ channels or the mRNA level of any Na+ channel subtypes did not change after chronic morphine. Also, chronic morphine significantly (P < 0.05) enhanced the magnitude of TRPV1 currents (−64 ± 11 pA/pF) vs. placebo (−18 ± 6 pA/pF). The increased excitability of sensory neurons by chronic morphine may be due to the shift in the voltage threshold of activation of TTX-R Na+ currents. Enhanced TRPV1 currents may have a complementary effect, with TTX-R Na+ currents on opiate-induced hyperexcitability of sensory neurons causing hypernociception. In conclusion, chronic morphine-induced hypernociception is associated with hyperexcitability and functional remodeling of TTX-R Na+ and TRPV1 channels of sensory neurons. PMID:22189556

  9. NSAIDs modulate GABA-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons

    PubMed Central

    ZHAO, LEI; LI, LI; MA, KE-TAO; WANG, YANG; LI, JING; SHI, WEN-YAN; ZHU, HE; ZHANG, ZHONG-SHUANG; SI, JUN-QIANG

    2016-01-01

    The ability of non-steroidal anti-inflammatory drugs (NSAIDs) to modulate γ-aminobutyrate (GABA)-activated currents via Ca2+-activated Cl− channels in rat dorsal root ganglion neurons (DRG), was examined in the present study. During the preparation of DRG neurons harvested from Sprague-Dawley rats, the whole-cell recording technique was used to record the effect of NSAIDs on GABA-activated inward currents, and the expression levels of the TMEM16A and TMEM16B subunits were revealed. In the event that DRG neurons were pre-incubated for 20 sec with niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) prior to the administration of GABA, the GABA-induced inward currents were diminished markedly in the majority of neurons examined (96.3%). The inward currents induced by 100 µmol/l GABA were attenuated by (0±0.09%; neurons = 4), (5.32±3.51%; neurons = 6), (21.3±4.00%; neurons = 5), (33.8±5.20%; neurons = 17), (52.2±5.10%; neurons = 4) and (61.1±4.12%; neurons = 12) by 0.1, 1, 3, 10, 30 and 100 µmol/l NFA, respectively. The inward currents induced by 100 µmol/l GABA were attenuated by (13.8±6%; neurons = 6), (23.2±14.7%; neurons = 6) and (29.7±9.1%; neurons = 9) by 3, 10 and 30 µmol/l NPPB, respectively. NFA and NPPB dose-dependently inhibited GABA-activated currents with half maximal inhibitory concentration (IC50) values of 6.7 and 11 µmol/l, respectively. The inhibitory effect of 100 µmol/l NFA on the GABA-evoked inward current were also strongly inhibited by nitrendipine (NTDP; an L-type calcium channel blocker), 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid tetrakis (a highly selective calcium chelating reagent), caffeine (a widely available Ca2+ consuming drug) and calcium-free extracellular fluid, in a concentration-dependent manner. Immunofluorescent staining indicated that TMEM16A and TMEM16B expression was widely distributed in DRG neurons. The results suggest that NSAIDs may be able to regulate Ca2

  10. Response to pulsed and continuous radiofrequency lesioning of the dorsal root ganglion and segmental nerves in patients with chronic lumbar radicular pain.

    PubMed

    Simopoulos, Thomas T; Kraemer, Jan; Nagda, Jyotsna V; Aner, Musa; Bajwa, Zahid H

    2008-01-01

    We aimed to prospectively evaluate the response and safety of pulsed and continuous radiofrequecy lesioning of the dorsal root ganglion/segmental nerves in patients with chronic lumbosacral radicular pain. Seventy-six patients with chronic lumbosacral radicular pain refractory to conventional therapy met the inclusion criteria and were randomly assigned to one of 2 types of treatment, pulsed radiofrequency lesioning of the dorsal root ganglion/segmental nerve or pulsed radiofrequency followed immediately by continuous radiofrequency. Patients were carefully evaluated for neurologic deficits and side effects. The response was evaluated at 2 months and was then tracked monthly. A Kaplan-Meier analysis was used to illustrate the probability of success over time and a Box-Whisker analysis was applied to determine the mean duration of a successful analgesic effect. Two months after undergoing radiofrequency treatment, 70% of the patients treated with pulsed radiofrequency and 82% treated with pulsed and continuous radiofrequency had a successful reduction in pain intensity. The average duration of successful analgesic response was 3.18 months (+/- 2.81) in the group treated with pulsed radiofrequency and 4.39 months (+/-3.50) in those patients treated with pulsed and continuous radiofrequency lesioning. A Kaplan-Meier analysis illustrated that in both treatment groups the chance of success approached 50% in each group at 3 months. The vast majority of patients had lost any beneficial effects by 8 months. There was no statistical difference between the 2 treatment groups. No side effects or neurological deficits were found in either group. Pulsed mode radiofrequency of the dorsal root ganglion of segmental nerves appears to be a safe treatment for chronic lumbosacral radicular pain. A significant number of patients can derive at least a short-term benefit. The addition of heat via continuous radiofrequency does not offer a significant advantage. A randomized controlled

  11. Propofol Modulates Agonist-induced Transient Receptor Potential Vanilloid Subtype-1 Receptor Desensitization via a Protein Kinase Cε-dependent Pathway in Mouse Dorsal Root Ganglion Sensory Neurons

    PubMed Central

    Wickley, Peter J.; Yuge, Ryo; Russell, Mary S.; Zhang, Hongyu; Sulak, Michael A.; Damron, Derek S.

    2011-01-01

    Background The activity of transient receptor potential vanilloid subtype-1 (TRPV1) receptors, key nociceptive transducers in dorsal root ganglion sensory neurons, is enhanced by protein kinase C ε (PKCε) activation. The intravenous anesthetic propofol has been shown to activate PKCε. Our objectives were to examine whether propofol modulates TRPV1 function in dorsal root ganglion neurons via activation of PKCε. Methods Lumbar dorsal root ganglion neurons from wild-type and PKCε-null mice were isolated and cultured for 24 h. Intracellular free Ca2+ concentration was measured in neurons by using fura-2 acetoxymethyl ester. The duration of pain-associated behaviors was also assessed. Phosphorylation of PKCε and TRPV1 and the cellular translocation of PKCε from cytosol to membrane compartments were assessed by immunoblot analysis. Results In wild-type neurons, repeated stimulation with capsaicin (100 nM) progressively decreased the transient rise in intracellular free Ca2+ concentration. After desensitization, exposure to propofol rescued the Ca2+ response. The resensitizing effect of propofol was absent in neurons obtained from PKCε-null mice. Moreover, the capsaicin-induced desensitization of TRPV1 was markedly attenuated in the presence of propofol in neurons from wild-type mice but not in neurons from PKCε-null mice. Propofol also prolonged the duration of agonist-induced pain associated behaviors in wild-type mice. In addition, propofol increased phosphorylation of PKCε as well as TRPV1 and stimulated translocation of PKCε from cytosolic to membrane fraction. Discussion Our results indicate that propofol modulates TRPV1 sensitivity to capsaicin and that this most likely occurs through a PKCε-mediated phosphorylation of TRPV1. PMID:20808213

  12. F-actin links Epac-PKC signaling to purinergic P2X3 receptor sensitization in dorsal root ganglia following inflammation

    PubMed Central

    Gu, Yanping; Wang, Congying; Li, GuangWen

    2016-01-01

    Sensitization of purinergic P2X3 receptors (P2X3Rs) contributes to the production of exaggerated nociceptive responses following inflammatory injury. We showed previously that prostaglandin E2 (PGE2) potentiates P2X3R-mediated ATP currents in dorsal root ganglion neurons isolated from both control and complete Freund’s adjuvant-induced inflamed rats. PGE2 potentiation of ATP currents depends only on PKA signaling in control neurons, but it depends on both PKA and PKC signaling in inflamed neurons. We further found that inflammation evokes an increase in exchange proteins directly activated by cAMP (Epacs) in dorsal root ganglions. This increase promotes the activation of PKC to produce a much enhanced PGE2 effect on ATP currents and to elicit Epac-dependent flinch nocifensive behavioral responses in complete Freund’s adjuvant rats. The link between Epac-PKC signaling and P2X3R sensitization remains unexplored. Here, we show that the activation of Epacs promotes the expression of phosphorylated PKC and leads to an increase in the cytoskeleton, F-actin, expression at the cell perimeter. Depolymerization of F-actin blocks PGE2-enhanced ATP currents and inhibits P2X3R-mediated nocifensive responses after inflammation. Thus, F-actin is dynamically involved in the Epac-PKC-dependent P2X3R sensitization. Furthermore, Epacs induce a PKC-dependent increase in the membrane expression of P2X3Rs. This increase is abolished by F-actin depolymerization, suggesting that F-actin mediates Epac-PKC signaling of P2X3R membrane expression. Thus, after inflammation, an Epac-PKC dependent increase in F-actin in dorsal root ganglion neurons enhances the membrane expression of P2X3Rs to bring about sensitization of P2X3Rs and abnormal pain behaviors. PMID:27385722

  13. EXPRESS: F-actin links Epac-PKC signaling to purinergic P2X3 receptors sensitization in dorsal root ganglia following inflammation.

    PubMed

    Gu, Yanping; Wang, Congying; Li, Guangwen; Huang, Li-Yen Mae

    2016-01-01

    Sensitization of purinergic P2X3 receptors (P2X3Rs) contributes to the production of exaggerated nociceptive responses following inflammatory injury. We showed previously that prostaglandin E2 (PGE2) potentiates P2X3R-mediated ATP currents in dorsal root ganglion neurons isolated from both control and complete Freund’s adjuvant-induced inflamed rats. PGE2 potentiation of ATP currents depends only on PKA signaling in control neurons, but it depends on both PKA and PKC signaling in inflamed neurons. We further found that inflammation evokes an increase in exchange proteins directly activated by cAMP (Epacs) in dorsal root ganglions. This increase promotes the activation of PKC to produce a much enhanced PGE2 effect on ATP currents and to elicit Epac-dependent flinch nocifensive behavioral responses in complete Freund’s adjuvant rats. The link between Epac-PKC signaling and P2X3R sensitization remains unexplored. Here, we show that the activation of Epacs promotes the expression of phosphorylated PKC and leads to an increase in the cytoskeleton, F-actin, expression at the cell perimeter. Depolymerization of F-actin blocks PGE2-enhanced ATP currents and inhibits P2X3R-mediated nocifensive responses after inflammation. Thus, F-actin is dynamically involved in the Epac-PKC-dependent P2X3R sensitization. Furthermore, Epacs induce a PKC-dependent increase in the membrane expression of P2X3Rs. This increase is abolished by F-actin depolymerization, suggesting that F-actin mediates Epac-PKC signaling of P2X3R membrane expression. Thus, after inflammation, an Epac-PKC dependent increase in F-actin in dorsal root ganglion neurons enhances the membrane expression of P2X3Rs to bring about sensitization of P2X3Rs and abnormal pain behaviors.

  14. Interactions between Dorsal and Ventral Root Stimulation on the Generation of Locomotor-Like Activity in the Neonatal Mouse Spinal Cord

    PubMed Central

    2016-01-01

    Abstract We investigated whether dorsal (DR) and ventral root (VR) stimulus trains engage common postsynaptic components to activate the central pattern generator (CPG) for locomotion in the neonatal mouse spinal cord. VR stimulation did not activate the first order interneurons mediating the activation of the locomotor CPG by sacrocaudal afferent stimulation. Simultaneous stimulation of adjacent dorsal or ventral root pairs, subthreshold for evoking locomotor-like activity, did not summate to activate the CPG. This suggests that locomotor-like activity is triggered when a critical class of efferent or afferent axons is stimulated and does not depend on the number of stimulated axons or activated postsynaptic neurons. DR- and VR-evoked episodes exhibited differences in the coupling between VR pairs. In DR-evoked episodes, the coupling between the ipsilateral and contralateral flexor/extensor roots was similar and stronger than the bilateral extensor roots. In VR-evoked episodes, ipsilateral flexor/extensor coupling was stronger than both the contralateral flexor/extensor and the bilateral extensor coupling. For both types of stimulation, the coupling was greatest between the bilateral L1/L2 flexor-dominated roots. This indicates that the recruitment and/or the firing pattern of motoneurons differed in DR and VR-evoked episodes. However, the DR and VR trains do not appear to activate distinct CPGs because trains of DR and VR stimuli at frequencies too low to evoke locomotor-like activity did so when they were interleaved. These results indicate that the excitatory actions of VR stimulation converge onto the CPG through an unknown pathway that is not captured by current models of the locomotor CPG. PMID:27419215

  15. Interactions between Dorsal and Ventral Root Stimulation on the Generation of Locomotor-Like Activity in the Neonatal Mouse Spinal Cord.

    PubMed

    Pujala, Avinash; Blivis, Dvir; O'Donovan, Michael J

    2016-01-01

    We investigated whether dorsal (DR) and ventral root (VR) stimulus trains engage common postsynaptic components to activate the central pattern generator (CPG) for locomotion in the neonatal mouse spinal cord. VR stimulation did not activate the first order interneurons mediating the activation of the locomotor CPG by sacrocaudal afferent stimulation. Simultaneous stimulation of adjacent dorsal or ventral root pairs, subthreshold for evoking locomotor-like activity, did not summate to activate the CPG. This suggests that locomotor-like activity is triggered when a critical class of efferent or afferent axons is stimulated and does not depend on the number of stimulated axons or activated postsynaptic neurons. DR- and VR-evoked episodes exhibited differences in the coupling between VR pairs. In DR-evoked episodes, the coupling between the ipsilateral and contralateral flexor/extensor roots was similar and stronger than the bilateral extensor roots. In VR-evoked episodes, ipsilateral flexor/extensor coupling was stronger than both the contralateral flexor/extensor and the bilateral extensor coupling. For both types of stimulation, the coupling was greatest between the bilateral L1/L2 flexor-dominated roots. This indicates that the recruitment and/or the firing pattern of motoneurons differed in DR and VR-evoked episodes. However, the DR and VR trains do not appear to activate distinct CPGs because trains of DR and VR stimuli at frequencies too low to evoke locomotor-like activity did so when they were interleaved. These results indicate that the excitatory actions of VR stimulation converge onto the CPG through an unknown pathway that is not captured by current models of the locomotor CPG.

  16. Nav1.7 protein and mRNA expression in the dorsal root ganglia of rats with chronic neuropathic pain.

    PubMed

    Liu, Chao; Cao, Jing; Ren, Xiuhua; Zang, Weidong

    2012-07-15

    Neuropathic pain was produced by chronic constriction injury of the sciatic nerve in rats. Behavioral tests showed that the thresholds for thermal and mechanical hyperalgesia were significantly reduced in neuropathic pain rats 3-28 days following model induction. The results of immunohistochemistry, western blot assays and reverse transcription-PCR showed that Nav1.7 protein and mRNA expression was significantly increased in the injured dorsal root ganglia. These findings indicated that Nav1.7 might play an important role in the model of chronic neuropathic pain.

  17. Cytotoxic effect of commercially available methylprednisolone acetate with and without reduced preservatives on dorsal root ganglion sensory neurons in rats.

    PubMed

    Knezevic, Nebojsa Nick; Candido, Kenneth D; Cokic, Ivan; Krbanjevic, Aleksandar; Berth, Sarah L; Knezevic, Ivana

    2014-01-01

    Epidural and intrathecal injections of methylprednisolone acetate (MPA) have become the most commonly performed interventional procedures in the United States and worldwide in the last 2 decades. However neuraxial MPA injection has been dogged by controversy regarding the presence of different additives used in commercially prepared glucocorticoids. We previously showed that MPA could be rendered 85% free of polyethylene glycol (PEG) by a simple physical separation of elements in the suspension. The objective of the present study was to explore a possible cytotoxic effect of commercially available MPA (with intact or reduced preservatives) on rat sensory neurons. We exposed primary dissociated rat dorsal root ganglia (DRG) sensory neurons to commercially available MPA for 24 hours with either the standard (commercial) concentration of preservatives or to different fractions following separation (MPA suspension whose preservative concentration had been reduced, or fractions containing higher concentrations of preservatives). Cells were stained with the TUNEL assay kit to detect apoptotic cells and images were taken on the Bio-Rad Laser Sharp-2000 system. We also detected expression of caspase-3, as an indicator of apoptosis in cell lysates. We exposed sensory neurons from rat DRG to different concentrations of MPA from the original commercially prepared vial. TUNEL assay showed dose-related responses and increased percentages of apoptotic cells with increasing concentrations of MPA. Increased concentrations of MPA caused 1.5 - 2 times higher caspase-3 expression in DRG sensory neurons than in control cells (ANOVA, P = 0.001). Our results showed that MPA with reduced preservatives caused significantly less apoptosis observed with TUNEL assay labeling (P < 0.001) and caspase-3 immunoblotting (P = 0.001) than in neurons exposed to MPA from a commercially prepared vial or "clear phase" that contained higher concentrations of preservatives. Even though MPA with reduced

  18. Effects of intermedin on dorsal root ganglia in the transmission of neuropathic pain in chronic constriction injury rats.

    PubMed

    Xiong, Wei; Qiu, Shu-yi; Xu, Ling-yun; Zhang, Chun-ping; Yi, Yun; Wu, Qin; Huang, Li-ping; Liu, Shuang-mei; Wu, Bing; Peng, Li-chao; Song, Miao-miao; Gao, Yun; Liang, Shang-dong

    2015-07-01

    Neuropathic pain is a common and severely disabling state that affects millions of people worldwide. The P2X3 receptor plays a crucial role in facilitating pain transmission. Intermedin (IMD), which is also known as adrenomedullin 2 (AMD2) is a newly discovered hormone that is a member of the calcitonin/calcitonin gene-related peptide family. The present research investigates the effects of IMD on pain transmission in neuropathic pain states as mediated by P2X3 receptors in dorsal root ganglia (DRG). Chronic constriction injury (CCI) rats were used as the neuropathic pain model. Adult male Sprague-Dawley rats were randomly assigned to five groups as follows: blank control group (Control), sham operation group (Sham), CCI rats treated with saline group (CCI+NS), CCI rats treated with IMD1-53 group (CCI+IMD1-53 ), and CCI rats treated with IMD inhibitor IMD14-47 group (CCI+IMD14-47 ). The mechanical withdrawal threshold (MWT) was tested by the von Frey method, and the thermal withdrawal latency (TWL) was tested via automatic thermal stimulus instruments. Changes in the expression of P2X3 receptors and IMD in CCI rat L4/L5 DRG were detected using immunohistochemistry, reverse transcription-polymerase chain reaction, and Western blotting. After treatment with intrathecal injection (i.t.), mechanical and thermal hyperalgesia in the CCI+IMD1-53 group was maintained, but MWT and TWL in the CCI+IMD14-47 groups increased. The expression levels of P2X3 receptors and IMD in L4/L5 DRG in the CCI+NS and CCI+IMD1-53 groups were significantly increased compared with those in the Control group or the Sham group. After application of IMD14-47 in CCI rats, there was a decrease in the expression levels of P2X3 receptors and IMD in L4/L5 DRG. The phosphorylation of p38 and ERK1/2 in L4/L5 DRG in the CCI+NS group and the CCI+IMD1-53 group was stronger than that in the Control group or the Sham group; however, the phosphorylation of p38 and ERK1/2 in the CCI+IMD14-47 group was much

  19. Nerve growth factor (NGF) and diabetic neuropathy in the rat: morphological investigations of the sural nerve, dorsal root ganglion, and spinal cord.

    PubMed

    Unger, J W; Klitzsch, T; Pera, S; Reiter, R

    1998-09-01

    A number of functions for nerve growth factor (NGF) have been described over the past years, including its role for neuronal function and regeneration during toxic or metabolic neuropathies. In order to further assess the effects of NGF on the somatosensory system in diabetic neuropathy, the sural nerve, dorsal root ganglia (DRG), and dorsal horn of the spinal cord were investigated by morphological and quantitative methods in rats after 12 weeks of uncontrolled streptozotocin-induced diabetes mellitus. The results from our study suggest a twofold effect of NGF: (1) In sural nerve treatment with NGF (0.1 or 0.5 mg/kg) for 12 weeks was able to reverse distinct diabetes-related alterations in myelinated nerve fiber morphology, such as myelin thickness. These changes occurred in the entire myelinated population of sensory nerves and were not restricted to nociceptive nerve fibers. (2) The NGF effect on neurotransmitters of the sensory, nociceptive system was reflected by increased CGRP and substance P content in the DRG and in the dorsal horn of the spinal cord. No change of trkA receptor immunostaining was seen in DRGs of diabetic rats; however, a reduction of trkA immunoreactivity of DRG neurons was noted after long-term NGF treatment of healthy controls. The data demonstrate that NGF regulates a number of neuronal parameters along peripheral and central parts of the somatosensory pathway in the adult. This neurotrophic support may be essential for inducing functionally significant regenerative mechanisms in diabetic neuropathy.

  20. Calcitonin gene-related peptide produces skeletal muscle vasodilation following antidromic stimulation of unmyelinated afferents in the dorsal root in rats.

    PubMed

    Sato, A; Sato, Y; Shimura, M; Uchida, S

    2000-04-07

    In anesthetized rats, the contribution of calcitonin gene-related peptide (CGRP) to antidromic vasodilation of skeletal muscle blood flow (MBF) following electrical stimulation of muscle afferent was investigated by measuring biceps femoris MBF using laser Doppler flowmetry. Repetitive antidromic electrical stimulation of unmyelinated C fibers in ipsilateral dorsal roots at the 3rd-5th lumbar segments for 30 s caused an increase in MBF for 3-15 min (mean 4.5 min) without significant change in systemic arterial blood pressure. The increase in skeletal MBF started about 10 s after the onset of stimulation, and peaked at approximately 130% of the control value at about 30 s after the end of the 30 s period of stimulation. The MBF response was totally abolished by topical application of hCGRP (8-37), a CGRP receptor antagonist. It is concluded that antidromic vasodilation in skeletal muscles following stimulation of unmyelinated C afferents in dorsal roots is independent of systemic blood pressure and is mediated essentially by CGRP. It is suggested that this CGRP-related antidromic vasodilation may be important in the clinical improvement of skeletal MBF produced by physical therapy, e.g. acupuncture.

  1. Effect of TRPV4-p38 MAPK Pathway on Neuropathic Pain in Rats with Chronic Compression of the Dorsal Root Ganglion

    PubMed Central

    Qu, Yu-Juan; Zhang, Xiao; Fan, Zhen-Zhen; Huai, Juan; Teng, Yong-Bo; Zhang, Yang; Yue, Shou-Wei

    2016-01-01

    The aim of this study was to investigate the relationships among TRPV4, p38, and neuropathic pain in a rat model of chronic compression of the dorsal root ganglion. Mechanical allodynia appeared after CCD surgery, enhanced via the intrathecal injection of 4α-phorbol 12,13-didecanoate (4α-PDD, an agonist of TRPV4) and anisomycin (an agonist of p38), but was suppressed by Ruthenium Red (RR, an inhibitor of TRPV4) and SB203580 (an inhibitor of p38). The protein expressions of p38 and P-p38 were upregulated by 4α-PDD and anisomycin injection but reduced by RR and SB203580. Moreover, TRPV4 was upregulated by 4α-PDD and SB203580 and downregulated by RR and anisomycin. In DRG tissues, the numbers of TRPV4- or p38-positive small neurons were significantly changed in CCD rats, increased by the agonists, and decreased by the inhibitors. The amplitudes of ectopic discharges were increased by 4α-PDD and anisomycin but decreased by RR and SB203580. Collectively, these results support the link between TRPV4 and p38 and their intermediary role for neuropathic pain in rats with chronic compression of the dorsal root ganglion. PMID:27366753

  2. Variations in the lumbosacral ligament and associated changes in the lumbosacral region resulting in compression of the fifth dorsal root ganglion and spinal nerve.

    PubMed

    Briggs, C A; Chandraraj, S

    1995-01-01

    Sixty-five lumbosacral regions from adult cadavers were dissected and the position and relations of the lumbosacral ligament noted. The lumbosacral ligament was present in all specimens; in 22 (34%) it extended medially across the ventral ramus of the fifth lumbar nerve, and in six (9%) of these the underlying nerve was compressed and visibly flattened. On two of these specimens the nerve, together with its dorsal root ganglion, was removed, processed, and stained with Masson's trichrome. The compressed nerve showed increased thickness of endoneurial and perineurial connective tissue, and the cells of the dorsal root ganglion were smaller and surrounded by increased connective tissue, particularly at the periphery of the ganglion. Observation of the lumbosacral ligament and surrounding anatomical structures suggests that anatomical variation in this region may be attributed to the health of the lumbosacral articular elements. In those specimens showing compression of the fifth lumbar spinal nerve there was also narrowing of the lumbosacral interspace. In these the disc itself was compressed and showed degenerative changes. The articular processes at the lumbosacral joint were irregular, with thinning and fissuring of the artiuclar cartilage. It is suggested that the processes which lead to the further development of the ligament, by the formation of additional fibrous bands, are mechanical in nature and result from instability at the lumbosacral region itself. Instability subsequently leads to the initiation of a chain of degenerative changes, involving pathology at the lumbosacral disc and zygapophyseal joints.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Up-regulation of brain-derived neurotrophic factor in the dorsal root ganglion of the rat bone cancer pain model

    PubMed Central

    Tomotsuka, Naoto; Kaku, Ryuji; Obata, Norihiko; Matsuoka, Yoshikazu; Kanzaki, Hirotaka; Taniguchi, Arata; Muto, Noriko; Omiya, Hiroki; Itano, Yoshitaro; Sato, Tadasu; Ichikawa, Hiroyuki; Mizobuchi, Satoshi; Morimatsu, Hiroshi

    2014-01-01

    Metastatic bone cancer causes severe pain, but current treatments often provide insufficient pain relief. One of the reasons is that mechanisms underlying bone cancer pain are not solved completely. Our previous studies have shown that brain-derived neurotrophic factor (BDNF), known as a member of the neurotrophic family, is an important molecule in the pathological pain state in some pain models. We hypothesized that expression changes of BDNF may be one of the factors related to bone cancer pain; in this study, we investigated changes of BDNF expression in dorsal root ganglia in a rat bone cancer pain model. As we expected, BDNF mRNA (messenger ribonucleic acid) and protein were significantly increased in L3 dorsal root ganglia after intra-tibial inoculation of MRMT-1 rat breast cancer cells. Among the eleven splice-variants of BDNF mRNA, exon 1–9 variant increased predominantly. Interestingly, the up-regulation of BDNF is localized in small neurons (mostly nociceptive neurons) but not in medium or large neurons (non-nociceptive neurons). Further, expression of nerve growth factor (NGF), which is known as a specific promoter of BDNF exon 1–9 variant, was significantly increased in tibial bone marrow. Our findings suggest that BDNF is a key molecule in bone cancer pain, and NGF-BDNF cascade possibly develops bone cancer pain. PMID:25050075

  4. Neurite growth acceleration of adult Dorsal Root Ganglion neurons illuminated by low-level Light Emitting Diode light at 645 nm.

    PubMed

    Burland, Marion; Paris, Lambert; Quintana, Patrice; Bec, Jean-Michel; Diouloufet, Lucie; Sar, Chamroeun; Boukhaddaoui, Hassan; Charlot, Benoit; Braga Silva, Jefferson; Chammas, Michel; Sieso, Victor; Valmier, Jean; Bardin, Fabrice

    2015-06-01

    The effect of a 645 nm Light Emitting Diode (LED) light irradiation on the neurite growth velocity of adult Dorsal Root Ganglion (DRG) neurons with peripheral axon injury 4-10 days before plating and without previous injury was investigated. The real amount of light reaching the neurons was calculated by taking into account the optical characteristics of the light source and of media in the light path. The knowledge of these parameters is essential to be able to compare results of the literature and a way to reduce inconsistencies. We found that 4 min irradiation of a mean irradiance of 11.3 mW/cm(2) (corresponding to an actual irradiance reaching the neurons of 83 mW/cm(2)) induced a 1.6-fold neurite growth acceleration on non-injured neurons and on axotomized neurons. Although the axotomized neurons were naturally already in a rapid regeneration process, an enhancement was found to occur while irradiating with the LED light, which may be promising for therapy applications. Dorsal Root Ganglion neurons (A) without previous injury and (B) subjected to a conditioning injury.

  5. Effect of exposure to radio frequency radiation emitted by cell phone on the developing dorsal root ganglion of chick embryo: a light microscopic study.

    PubMed

    Ingole, I V; Ghosh, S K

    2012-12-01

    With an ever increasing number of cell phone users since late twentieth [corrected] century, magnitude of the problem of exposure to radiation emitted by cell phone is self evident. Extensive research had been devoted to incriminate or absolve it as a health hazard. Radiofrequency radiation emitted by cell phone had been stated to be a potent carcinogen, cytotoxic, genotoxic, mutagenic and neurobehavioral teratogen. Its effect on the brain had been a subject of extensive research evidently due to its proximity to the user's brain. While considering the biological effects of radiofrequency radiation, its intensity, frequency and the duration of exposure are important determinants. Nevertheless the results of these different studies have not been unequivocal. Considering the contradictory reports, the present work was undertaken to study the effect of such an exposure on the developing neural tissue of chick embryo. The processes of cell division and differentiation are fundamental to the development of any living being and are a sensitive index of any insult sustained at this stage. Neurons of dorsal root ganglion were selected for the present study as these ganglia were fully differentiated as early as fourth day of embryonic life. By varying duration of exposure, the embryos were exposed to different doses of radiation, sacrificed at different periods of incubation and subjected to histological processing. On light microscopic study it was observed that developing neurons of dorsal root ganglion suffered a damage which was dose dependent and persisted in spite of giving the exposure-free period between two exposures.

  6. Porphyrin-heme biosynthesis in organotypic cultures of mouse dorsal root ganglia. Effects of heme and lead on porphyrin synthesis and peripheral myelin.

    PubMed Central

    Whetsell, W O; Sassa, S; Kappas, A

    1984-01-01

    Well-myelinated cultures of mouse dorsal root ganglia incubated for 48 h with sigma-aminolevulinic acid (ALA) showed intense porphyrin fluorescence localized in myelin sheaths but not in axons or neuronal somata. When the cultures were continuously incubated with a high concentration of lead, focal swelling and segmental degeneration of myelin began to develop within 2 wk. Incubation of cultures with ALA after 3 wk of lead treatment revealed markedly decreased porphyrin fluorescence in myelin sheaths compared with untreated controls. After 6 wk of lead treatment, myelin showed severe segmental degeneration. Porphyrin fluorescence from ALA at this time was barely detectable in these cultures. No fluorescence was visible in the demyelinated axons; however, silver-impregnation staining after fixation demonstrated continuity of the axon despite the severe loss of myelin. When cultures were continuously incubated with lead and heme together for 6 wk, the segmental demyelination seen in cultures treated with lead alone did not occur. These findings suggest that the lead-induced segmental demyelination in cultured mouse dorsal root ganglia may be due to toxic effects of the metal on the heme biosynthetic pathway in myelinating cells and that exogenous heme may counteract this toxic effect of lead. Images PMID:6746908

  7. Effect of TRPV4-p38 MAPK Pathway on Neuropathic Pain in Rats with Chronic Compression of the Dorsal Root Ganglion.

    PubMed

    Qu, Yu-Juan; Zhang, Xiao; Fan, Zhen-Zhen; Huai, Juan; Teng, Yong-Bo; Zhang, Yang; Yue, Shou-Wei

    2016-01-01

    The aim of this study was to investigate the relationships among TRPV4, p38, and neuropathic pain in a rat model of chronic compression of the dorsal root ganglion. Mechanical allodynia appeared after CCD surgery, enhanced via the intrathecal injection of 4α-phorbol 12,13-didecanoate (4α-PDD, an agonist of TRPV4) and anisomycin (an agonist of p38), but was suppressed by Ruthenium Red (RR, an inhibitor of TRPV4) and SB203580 (an inhibitor of p38). The protein expressions of p38 and P-p38 were upregulated by 4α-PDD and anisomycin injection but reduced by RR and SB203580. Moreover, TRPV4 was upregulated by 4α-PDD and SB203580 and downregulated by RR and anisomycin. In DRG tissues, the numbers of TRPV4- or p38-positive small neurons were significantly changed in CCD rats, increased by the agonists, and decreased by the inhibitors. The amplitudes of ectopic discharges were increased by 4α-PDD and anisomycin but decreased by RR and SB203580. Collectively, these results support the link between TRPV4 and p38 and their intermediary role for neuropathic pain in rats with chronic compression of the dorsal root ganglion.

  8. Cdk5 inhibitor roscovitine alleviates neuropathic pain in the dorsal root ganglia by downregulating N-methyl-D-aspartate receptor subunit 2A.

    PubMed

    Yang, Lei; Gu, Xiaoping; Zhang, Wei; Zhang, Juan; Ma, Zhengliang

    2014-09-01

    Cyclin-dependent kinase 5 (Cdk5) is a member of the small proline-directed serine/threonine kinase family. Cdk5 is not involved in cell cycle regulation, but is implicated in neurodegenerative disorders. However, the role of Cdk5 in neuropathic pain remains unclear. This study aimed to evaluate the possibility that Cdk5 is involved in neuropathic pain in the dorsal root ganglia (DRG). We injected intrathecally Cdk5 inhibitor roscovitine in rat model of chronic compression of dorsal root ganglion and examined pain behaviors and the expression of N-methyl-d-aspartate receptor subunit 2A (NR2A) but not NR2B or NR1 in DRG. We found that roscovitine alleviated neuropathic pain, causing decline in paw withdrawal mechanical threshold and paw withdrawal thermal latency. Furthermore, roscovitine inhibited NR2A expression in DRG. These data suggest that Cdk5-NR2A pathway regulates neuropathic pain in DRG, and intrathecal injection of roscovitine could alleviate neuropathic pain. Our findings provide new insight into the analgesic effects of Roscovitine and identify Cdk5-NR2A pathway as a potential target for effective treatment of neuropathic pain.

  9. Dorsal root ganglion stimulation yielded higher treatment success rate for complex regional pain syndrome and causalgia at 3 and 12 months: a randomized comparative trial

    PubMed Central

    Deer, Timothy R.; Levy, Robert M.; Kramer, Jeffery; Poree, Lawrence; Amirdelfan, Kasra; Grigsby, Eric; Staats, Peter; Burton, Allen W.; Burgher, Abram H.; Obray, Jon; Scowcroft, James; Golovac, Stan; Kapural, Leonardo; Paicius, Richard; Kim, Christopher; Pope, Jason; Yearwood, Thomas; Samuel, Sam; McRoberts, W. Porter; Cassim, Hazmer; Netherton, Mark; Miller, Nathan; Schaufele, Michael; Tavel, Edward; Davis, Timothy; Davis, Kristina; Johnson, Linda; Mekhail, Nagy

    2016-01-01

    Abstract Animal and human studies indicate that electrical stimulation of dorsal root ganglion (DRG) neurons may modulate neuropathic pain signals. ACCURATE, a pivotal, prospective, multicenter, randomized comparative effectiveness trial, was conducted in 152 subjects diagnosed with complex regional pain syndrome or causalgia in the lower extremities. Subjects received neurostimulation of the DRG or dorsal column (spinal cord stimulation, SCS). The primary end point was a composite of safety and efficacy at 3 months, and subjects were assessed through 12 months for long-term outcomes and adverse events. The predefined primary composite end point of treatment success was met for subjects with a permanent implant who reported 50% or greater decrease in visual analog scale score from preimplant baseline and who did not report any stimulation-related neurological deficits. No subjects reported stimulation-related neurological deficits. The percentage of subjects receiving ≥50% pain relief and treatment success was greater in the DRG arm (81.2%) than in the SCS arm (55.7%, P < 0.001) at 3 months. Device-related and serious adverse events were not different between the 2 groups. Dorsal root ganglion stimulation also demonstrated greater improvements in quality of life and psychological disposition. Finally, subjects using DRG stimulation reported less postural variation in paresthesia (P < 0.001) and reduced extraneous stimulation in nonpainful areas (P = 0.014), indicating DRG stimulation provided more targeted therapy to painful parts of the lower extremities. As the largest prospective, randomized comparative effectiveness trial to date, the results show that DRG stimulation provided a higher rate of treatment success with less postural variation in paresthesia intensity compared to SCS. PMID:28030470

  10. Minimally invasive convection-enhanced delivery of biologics into dorsal root ganglia: validation in the pig model and prospective modeling in humans. Technical note.

    PubMed

    Pleticha, Josef; Maus, Timothy P; Christner, Jodie A; Marsh, Michael P; Lee, Kendall H; Hooten, W Michael; Beutler, Andreas S

    2014-10-01

    Dorsal root ganglia (DRG) are critical anatomical structures involved in nociception. Intraganglionic (IG) drug delivery is therefore an important route of administration for novel analgesic therapies. Although IG injection in large animal models is highly desirable for preclinical biodistribution and toxicology studies of new drugs, no method to deliver pharmaceutical agents into the DRG has been reported in any large species. The present study describes a minimally invasive technique of IG agent delivery in domestic swine, one of the most common large animal models. The technique utilizes CT guidance for DRG targeting and a custom-made injection assembly for convection enhanced delivery (CED) of therapeutic agents directly into DRG parenchyma. The DRG were initially visualized by CT myelography to determine the optimal access route to the DRG. The subsequent IG injection consisted of 3 steps. First, a commercially available guide needle was advanced to a position dorsolateral to the DRG, and the dural root sleeve was punctured, leaving the guide needle contiguous with, but not penetrating, the DRG. Second, the custom-made stepped stylet was inserted through the guide needle into the DRG parenchyma. Third, the stepped stylet was replaced by the custom-made stepped needle, which was used for the IG CED. Initial dye injections performed in pig cadavers confirmed the accuracy of DRG targeting under CT guidance. Intraganglionic administration of adeno-associated virus in vivo resulted in a unilateral transduction of the injected DRG, with 33.5% DRG neurons transduced. Transgene expression was also found in the dorsal root entry zones at the corresponding spinal levels. The results thereby confirm the efficacy of CED by the stepped needle and a selectivity of DRG targeting. Imaging-based modeling of the procedure in humans suggests that IG CED may be translatable to the clinical setting.

  11. Correlation of preoperative MRI with the long-term outcomes of dorsal root entry zone lesioning for brachial plexus avulsion pain.

    PubMed

    Ko, Andrew L; Ozpinar, Alp; Raskin, Jeffrey S; Magill, Stephen T; Raslan, Ahmed M; Burchiel, Kim J

    2016-05-01

    OBJECT Lesioning of the dorsal root entry zone (DREZotomy) is an effective treatment for brachial plexus avulsion (BPA) pain. The role of preoperative assessment with MRI has been shown to be unreliable for determining affected levels; however, it may have a role in predicting pain outcomes. Here, DREZotomy outcomes are reviewed and preoperative MRI is examined as a possible prognostic factor. METHODS A retrospective review was performed of an institutional database of patients who had undergone brachial plexus DREZ procedures since 1995. Preoperative MRI was examined to assess damage to the DREZ or dorsal horn, as evidenced by avulsion of the DREZ or T2 hyperintensity within the spinal cord. Phone interviews were conducted to assess the long-term pain outcomes. RESULTS Between 1995 and 2012, 27 patients were found to have undergone cervical DREZ procedures for BPA. Of these, 15 had preoperative MR images of the cervical spine available for review. The outcomes were graded from 1 to 4 as poor (no significant relief), good (more than 50% pain relief), excellent (more than 75% pain relief), or pain free, respectively. Overall, DREZotomy was found to be a safe, efficacious, and durable procedure for relief of pain due to BPA. The initial success rate was 73%, which declined to 66% at a median follow-up time of 62.5 months. Damage to the DREZ or dorsal horn was significantly correlated with poorer outcomes (p = 0.02). The average outcomes in patients without MRI evidence of DREZ or dorsal horn damage was significantly higher than in patients with such damage (3.67 vs 1.75, t-test; p = 0.001). A longer duration of pain prior to operation was also a significant predictor of treatment success (p = 0.004). CONCLUSIONS Overall, the DREZotomy procedure has a 66% chance of achieving meaningful pain relief on long-term follow-up. Successful pain relief is associated with the lack of damage to the DREZ and dorsal horn on preoperative MRI.

  12. The non-immunosuppressive immunophilin ligand GPI-1046 potently stimulates regenerating axon growth from adult mouse dorsal root ganglia cultured in Matrigel.

    PubMed

    Khan, Z; Ferrari, G; Kasper, M; Tonge, D A; Steiner, J P; Hamilton, G S; Gordon-Weeks, P R

    2002-01-01

    We used explant cultures of adult mouse dorsal root ganglia with spinal nerve attached growing in Matrigel to assess the effects of the non-immunosuppressive immunophilin ligand GPI-1046 [Snyder et al. (1998) TIPS 19, 21-26] on the growth rate of regenerating sensory axons and found a potent stimulation of axon growth. In these explant cultures, naked, unfasciculated axons emerge from the cut end of the spinal nerve and continue to grow in the Matrigel for up to eight days [Tonge et al. (1996) Neuroscience 73, 541-551]. Some axons are entirely smooth whilst others show prominent varicosities. Some of the former express the phosphorylated neurofilament epitope recognised by monoclonal antibody RT97, a marker for large calibre, myelinated axons, whilst the latter express calcitonin gene-related peptide, predominantly a marker for unmyelinated, and small diameter myelinated sensory axons. Many of the axons in these cultures also express the low-affinity neurotrophin receptor p75. GPI-1046 has been shown to have striking stimulatory effects on embryonic primary sensory axons growing in vitro and it was therefore of interest to see whether it could also enhance regenerating sensory axon growth from the adult ganglia in our cultures. GPI-1046 potently stimulated axon growth in our cultures in a dose-dependent manner. The stimulatory effect was not dependent on the class of sensory axon. These observations show that GPI-1046 is a potent stimulator of regenerating axons from adult, primary sensory neurones. The cellular site of action of GPI-1046 is unknown. To distinguish between a direct effect of the drug on neurones and an indirect effect we compared the effects of GPI-1046 on explant and dissociated cultures. In confirmation of previous results, we found that GPI-1046 potently stimulated axon outgrowth from explants of embryonic chick dorsal root ganglia. However, the drug was without effect on dissociated embryonic dorsal root ganglion neurones, suggesting that non

  13. Role of puerarin in the signalling of neuropathic pain mediated by P2X3 receptor of dorsal root ganglion neurons.

    PubMed

    Xu, Changshui; Xu, Wenyuan; Xu, Hong; Xiong, Wei; Gao, Yun; Li, Guilin; Liu, Shuangmei; Xie, Jinyan; Tu, Guihua; Peng, Haiying; Qiu, Shuyi; Liang, Shangdong

    2012-01-04

    Tissue injury or inflammation of the nervous system may result in chronic neuropathic pain characterized by sensitivity to painful stimuli. P2X(3) receptors play a crucial role in facilitating pain transmission. Puerarin is an active compound of a traditional Chinese medicine Ge-gen, and Ge-gen soup has anti-inflammatory effects. The present research investigated the role of puerarin in the signalling of chronic neuropathic pain mediated by P2X(3) receptors of rat dorsal root ganglion neurons. Chronic constriction injury (CCI) rat model was adopted. Sprague-Dawley rats were randomly divided into blank control group (Ctrl), sham group (Sham), puerarin-treated control group (Ctrl+PUE), chronic constriction injury (CCI) group and puerarin-treated CCI group (CCI+PUE). Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were measured by the von-Frey test and the Hargreaves' test respectively. The stain values of P2X(3) protein and mRNA in L4/L5 dorsal root ganglion (DRG) were detected by immunohistochemistry, western blot and in situ hybridization. At day 4-7 after the operation of CCI rats, MWT and TWL in group CCI and CCI+PUE were lower than those in group Ctrl, Sham and Ctrl+PUE, while there was no difference among group Ctrl, Sham and Ctrl+PUE. At day 7-10 after operation, MWT and TWL in group CCI+PUE was higher than those in group CCI, but there was no significant difference between group CCI+PUE and group Ctrl (p>0.05). At day 14 after operation, the stain values of P2X(3) proteins and mRNAs in L4/L5 DRG of group CCI were higher than those in group Ctrl, Sham, Ctrl+PUE and CCI+PUE, while the stain values of P2X(3) proteins and mRNAs in group CCI+PUE were significantly decreased compared with those in group CCI. Therefore, puerarin may alleviate neuropathic pain mediated by P2X(3) receptors in dorsal root ganglion neurons.

  14. Percutaneous radiofrequency lesions adjacent to the dorsal root ganglion alleviate spasticity and pain in children with cerebral palsy: pilot study in 17 patients

    PubMed Central

    2010-01-01

    Background Cerebral palsy (CP) may cause severe spasticity, requiring neurosurgical procedures. The most common neurosurgical procedures are continuous infusion of intrathecal baclofen and selective dorsal rhizotomy. Both are invasive and complex procedures. We hypothesized that a percutaneous radiofrequency lesion of the dorsal root ganglion (RF-DRG) could be a simple and safe alternative treatment. We undertook a pilot study to test this hypothesis. Methods We performed an RF-DRG procedure in 17 consecutive CP patients with severe hip flexor/adductor spasms accompanied by pain or care-giving difficulties. Six children were systematically evaluated at baseline, and 1 month and 6 months after treatment by means of the Modified Ashworth Scale (MAS), Gross Motor Function Measure (GMFM) and a self-made caregiver's questionnaire. Eleven subsequent children were evaluated using a Visual Analogue Scale (VAS) for spasticity, pain and ease of care. Results A total of 19 RF-DRG treatments were performed in 17 patients. We found a small improvement in muscle tone measured by MAS, but no effect on the GMFM scale. Despite this, the caregivers of these six treated children unanimously stated that the quality of life of their children had indeed improved after the RF-DRG. In the subsequent 11 children we found improvements in all VAS scores, in a range comparable to the conventional treatment options. Conclusion RF-DRG is a promising new treatment option for severe spasticity in CP patients, and its definitive effectiveness remains to be defined in a randomised controlled trial. PMID:20569438

  15. Virus-Mediated Knockdown of Nav1.3 in Dorsal Root Ganglia of STZ-Induced Diabetic Rats Alleviates Tactile Allodynia

    PubMed Central

    Tan, Andrew M; Samad, Omar A; Dib-Hajj, Sulayman D; Waxman, Stephen G

    2015-01-01

    Diabetic neuropathic pain affects a substantial number of people and represents a major public health problem. Available clinical treatments for diabetic neuropathic pain remain only partially effective and many of these treatments carry the burden of side effects or the risk of dependence. The misexpression of sodium channels within nociceptive neurons contributes to abnormal electrical activity associated with neuropathic pain. Voltage-gated sodium channel Nav1.3 produces tetrodotoxin-sensitive sodium currents with rapid repriming kinetics and has been shown to contribute to neuronal hyperexcitability and ectopic firing in injured neurons. Suppression of Nav1.3 activity can attenuate neuropathic pain induced by peripheral nerve injury. Previous studies have shown that expression of Nav1.3 is upregulated in dorsal root ganglion (DRG) neurons of diabetic rats that exhibit neuropathic pain. Here, we hypothesized that viral-mediated knockdown of Nav1.3 in painful diabetic neuropathy would reduce neuropathic pain. We used a validated recombinant adeno-associated virus (AAV)-shRNA-Nav1.3 vector to knockdown expression of Nav1.3, via a clinically applicable intrathecal injection method. Three weeks following vector administration, we observed a significant rate of transduction in DRGs of diabetic rats that concomitantly reduced neuronal excitability of dorsal horn neurons and reduced behavioral evidence of tactile allodynia. Taken together, these findings offer a novel gene therapy approach for addressing chronic diabetic neuropathic pain. PMID:26101954

  16. Accumulation of immunoglobulin G against Dermatophagoides farinae tropomyosin in dorsal root ganglia of NC/Nga mice with atopic dermatitis-like symptoms.

    PubMed

    Otsu, Ayaka; Kawasaki, Hiroaki; Tominaga, Mitsutoshi; Shigenaga, Ayako; Matsuda, Hironori; Takahashi, Nobuaki; Nakajima, Tadaaki; Naito, Hisashi; Baba, Takeshi; Ogawa, Hideoki; Tomooka, Yasuhiro; Yamakura, Fumiyuki; Takamori, Kenji

    2017-04-15

    Atopic dermatitis (AD), a chronic inflammatory skin disease, manifests as intractable itch, but its underlying mechanisms are poorly understood. This study assessed the relationship between immunoglobulin G (IgG) and dorsal root ganglia (DRG) in NC/Nga mice, a model of AD that manifests AD-like symptoms including itch. Immunohistochemical analysis showed large amounts of IgG in DRG extracts of NC/Nga mice with AD-like dermatitis, with a large fraction of the IgG distributed in satellite glial cells of the DRG. Proteomic analysis showed that this IgG was reactive against tropomyosin of Dermatophagoides farinae. These findings indicate that the accumulation of anti-tropomyosin IgG in DRG of atopic NC/Nga mice may be associated with the pathogenesis of AD-like symptoms, including itch. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Effects of dragon's blood resin and its component loureirin B on tetrodotoxin-sensitive voltage-gated sodium currents in rat dorsal root ganglion neurons.

    PubMed

    Xiangming, Liu; Su, Chen; Shijin, Yin; Zhinan, Mei

    2004-08-01

    Using whole-cell patch clamp technique on the membrane of freshly isolated dorsal root ganglion (DRG) neurons, the effects of dragon's blood resin and its important component loureirin B on tetrodotoxin-sensitive (TTX-S) voltage-gated sodium currents were observed. The results show that both blood resin and loureirin B could suppress TTX-S voltage-gated sodium currents in a dose-dependent way. The peak current amplitudes and the steady-state activation and inactivation curves are also made to shift by 0.05% blood resin and 0.2 mmol/L loureirin B. These results demonstrate that the effects of blood resin on TTX-S sodium current may contribute to loureirin B in blood resin. Perhaps the analgesic effect of blood resin is caused partly by loureirin B directly interfering with the nociceptive transmission of primary sensory neurons.

  18. The protective effect of resveratrol in the transmission of neuropathic pain mediated by the P2X7 receptor in the dorsal root ganglia.

    PubMed

    Xie, Jinyan; Liu, Shuangmei; Wu, Bing; Li, Guilin; Rao, Shenqiang; Zou, Lifang; Yi, Zhihua; Zhang, Chunping; Jia, Tianyu; Zhao, Shanhong; Schmalzing, Günther; Hausmann, Ralf; Nie, Hong; Li, Guodong; Liang, Shangdong

    2017-02-01

    The P2X7 receptor mediates afferent nerve activation and is related to chronic neuropathic pain. Resveratrol (RES) has also been reported to exhibit anti-inflammatory effects. In this study, we investigated the neuroprotective effect of RES on the transmission of neuropathic pain mediated by the P2X7 receptor. The P2X7 mRNA and protein expression levels in L4-L5 dorsal root ganglia (DRG)s of the chronic constriction injury (CCI) group were significantly higher than those observed in the Ctrl + NS, Sham + RES and Sham groups. RES increased the threshold of thermal and mechanical hypersensitivity in rats with chronic neuropathic pain. The P2X7 mRNA and protein expression levels in the CCI + RES group were decreased compared with those in the CCI group. Our results showed that RES inhibited the upregulated co-expression of P2X7 and glial fibrillary acidic protein (GFAP, a marker of satellite glial cells) in satellite glial cells of DRG in the CCI group. The results demonstrated that the expression of GFAP was increased in the CCI group and that RES inhibited the upregulated expression of GFAP in the rats in the CCI group. In addition, the phosphorylation levels of p38 and extracellular regulated protein kinases (ERK)1/2 in the CCI group were markedly higher than those observed in the Ctrl + NS, Sham + RES and Sham groups, whereas the phosphorylation levels of p38 and ERK1/2 in CCI + RES group were markedly lower than those observed in the CCI group. RES inhibited BzATP-activated currents in DRG non-neurons in the CCI rats. Our data provide evidence that RES may suppress the transmission of neuropathic pain mediated by the P2X7 receptor in the satellite glial cells of dorsal root ganglia.

  19. A non-pungent triprenyl phenol of fungal origin, scutigeral, stimulates rat dorsal root ganglion neurons via interaction at vanilloid receptors.

    PubMed

    Szallasi, A; Bíró, T; Szabó, T; Modarres, S; Petersen, M; Klusch, A; Blumberg, P M; Krause, J E; Sterner, O

    1999-03-01

    1. A [3H]-resiniferatoxin (RTX) binding assay utilizing rat spinal cord membranes was employed to identify novel vanilloids in a collection of natural products of fungal origin. Of the five active compounds found (scutigeral, acetyl-scutigeral, ovinal, neogrifolin, and methyl-neogrifolin), scutigeral (Ki=19 microM), isolated from the edible mushroom Albatrellus ovinus, was selected for further characterization. 2. Scutigeral induced a dose-dependent 45Ca uptake by rat dorsal root ganglion neurons with an EC50 of 1.6 microM, which was fully inhibited by the competitive vanilloid receptor antagonist capsazepine (IC50=5.2 microM). 3. [3H]-RTX binding isotherms were shifted by scutigeral (10-80 microM) in a competitive manner. The Schild plot of the data had a slope of 0.8 and gave an apparent Kd estimate for scutigeral of 32 microM. 4. Although in the above assays scutigeral mimicked capsaicin, it was not pungent on the human tongue up to a dose of 100 nmol per tongue, nor did it provoke protective wiping movements in the rat (up to 100 microM) upon intraocular instillation. 5. In accord with being non-pungent, scutigeral (5 microM) did not elicit a measurable inward current in isolated rat dorsal root ganglion neurons under voltage-clamp conditions. It did, however, reduce the proportion of neurons (from 61 to 15%) that responded to a subsequent capsaicin (1 microM) challenge. In these neurons, scutigeral both delayed (from 27 to 72 s) and diminished (from 5.0 to 1.9 nA) the maximal current evoked by capsaicin. 6. In conclusion, scutigeral and its congeners form a new chemical class of vanilloids, the triprenyl phenols. Scutigeral promises to be a novel chemical lead for the development of orally active, non-pungent vanilloids.

  20. Allele-specific differences in activity of a novel cannabinoid receptor 1 (CNR1) gene intronic enhancer in hypothalamus, dorsal root ganglia, and hippocampus.

    PubMed

    Nicoll, Gemma; Davidson, Scott; Shanley, Lynne; Hing, Ben; Lear, Marissa; McGuffin, Peter; Ross, Ruth; MacKenzie, Alasdair

    2012-04-13

    Polymorphisms within intron 2 of the CNR1 gene, which encodes cannabinoid receptor 1 (CB(1)), have been associated with addiction, obesity, and brain volume deficits. We used comparative genomics to identify a polymorphic (rs9444584-C/T) sequence (ECR1) in intron 2 of the CNR1 gene that had been conserved for 310 million years. The C-allele of ECR1 (ECR1(C)) acted as an enhancer in hypothalamic and dorsal root ganglia cells and responded to MAPK activation through the MEKK pathway but not in hippocampal cells. However, ECR1(T) was significantly more active in hypothalamic and dorsal root ganglia cells but, significantly, and in contrast to ECR1(C), was highly active in hippocampal cells where it also responded strongly to activation of MAPK. Intriguingly, rs9444584 is in strong linkage disequilibrium with two other SNPs (rs9450898 (r(2) = 0.841) and rs2023239 (r(2) = 0.920)) that have been associated with addiction, obesity (rs2023239), and reduced fronto-temporal white matter volumes in schizophrenia patients as a result of cannabis misuse (rs9450898). Considering their high linkage disequilibrium and the increased response of ECR1(T) to MAPK signaling when compared with ECR1(C), it is possible that the functional effects of the different alleles of rs9444584 may play a role in the conditions associated with rs9450898 and rs2023239. Further analysis of the different alleles of ECR1 may lead to a greater understanding of the role of CNR1 gene misregulation in these conditions as well as chronic inflammatory pain.

  1. Nerve injury induces a Gem-GTPase-dependent downregulation of P/Q-type Ca2+ channels contributing to neurite plasticity in dorsal root ganglion neurons.

    PubMed

    Scamps, Frédérique; Sangari, Sina; Bowerman, Melissa; Rousset, Mathieu; Bellis, Michel; Cens, Thierry; Charnet, Pierre

    2015-02-01

    Small RGK GTPases, Rad, Gem, Rem1, and Rem2, are potent inhibitors of high-voltage-activated (HVA) Ca(2+) channels expressed in heterologous expression systems. However, the role of this regulation has never been clearly demonstrated in the nervous system. Using transcriptional analysis, we show that peripheral nerve injury specifically upregulates Gem in mice dorsal root ganglia. Following nerve injury, protein expression was increased in ganglia and peripheral nerve, mostly under its phosphorylated form. This was confirmed in situ and in vitro in dorsal root ganglia sensory neurons. Knockdown of endogenous Gem, using specific small-interfering RNA (siRNA), increased the HVA Ca(2+) current only in the large-somatic-sized neurons. Combining pharmacological analysis of the HVA Ca(2+) currents together with Gem siRNA-transfection of larger sensory neurons, we demonstrate that only the P/Q-type Ca(2+) channels were enhanced. In vitro analysis of Gem affinity to various CaVβx-CaV2.x complexes and immunocytochemical studies of Gem and CaVβ expression in sensory neurons suggest that the specific inhibition of the P/Q channels relies on both the regionalized upregulation of Gem and the higher sensitivity of the endogenous CaV2.1-CaVβ4 pair in a subset of sensory neurons including the proprioceptors. Finally, pharmacological inhibition of P/Q-type Ca(2+) current reduces neurite branching of regenerating axotomized neurons. Taken together, the present results indicate that a Gem-dependent P/Q-type Ca(2+) current inhibition may contribute to general homeostatic mechanisms following a peripheral nerve injury.

  2. Application of radiofrequency thermocoagulation combined with adriamycin injection in dorsal root ganglia for controlling refractory pain induced by rib metastasis of lung cancer (a STROBE-compliant article).

    PubMed

    Xie, Guang-Lun; Guo, Da-Peng; Li, Zhi-Gang; Liu, Chang; Zhang, Wei

    2016-10-01

    This study aimed to observe the therapeutic effects and adverse reactions of radiofrequency thermocoagulation combined with adriamycin injection in dorsal root ganglia on lung cancer rib metastasis-related refractory pain which has no response to conventional therapy.This study contained 27 patients with lung cancer rib metastasis-related moderate or severe pain which had no response to conventional therapy. Under computed tomography (CT)-guidance, radiofrequency puncture need reached the corresponding intervertebral foramens to ensure needle point near dorsal root ganglia (DRG) by sensory and motor stimulation tests, and then radiofrequency thermocoagulation was performed on each corresponding DRG followed by injection of 0.5 to 1 mL of adriamycin (0.5%). The conditions of pain and complications were observed before management and 3 days, 1 month, and 3 months after management, respectively.Numerical rating scale (NRS) scores and dosage of morphine were all significantly decreased after management as compared with those before management (all P < 0.01). Although the number of patients with chest wall numbness was significantly increased after management as compared with that before management (all P < 0.01), the degree of chest wall numbness was tolerable. There were no statistical differences between before and after management in nausea and vomiting, and constipation.CT-guided radiofrequency thermocoagulation combined with adriamycin injection in DRG can effectively control lung cancer rib metastasis-related pain which has no response to conventional therapy. This combinatory treatment regimen is featured by better therapeutic effects and a few complications, so it is worthy of being recommended in clinical application.

  3. Pulsed radiofrequency effects on the lumbar ganglion of the rat dorsal root: a morphological light and transmission electron microscopy study at acute stage

    PubMed Central

    Reguzzoni, Marcella; Sangiorgi, Simone; Reverberi, Claudio; Borsani, Elisa; Rodella, Luigi F.; Dario, Alessandro; Tomei, Giustino; Dell’Orbo, Carlo

    2009-01-01

    Since the dorsal root ganglia represent the first structure of pain modulation, they are the target of the newest therapies of neuropathic pain. Between these, pulsed radiofrequency (PRF) has been described among the promising non-invasive methods. Although the results encourage the clinical use of this procedure, their mechanism of action is still unclear. Aim of our study was to analyze acute effects of PRF on the rat lumbar ganglion and on nervous fibres running inside it. Clinical works describe PRF treatment as a techinque without any visible neurological deficit. The few disposable histological works are contractictory: some describe no signs of cellular damage and some demonstrate visible intracellular modifications. A total of 20 male Wistar rats were deeply anesthesized. Ten were positioned in a stereotactic system, and exposed to PRF at 2 Hz for 30 s after exposition of paravertebral muscles and positioning of a stimulation needle on left L4 ganglion. The other ten were used as controls. After 1 h, the left dorsal root ganglions L3, L4, L5 of the 20 animals were explanted, fixed in 2.5% Karnowsky solution and prepared for light and transmission electron microscopy. At light microscopy no differences between treated and control animals were observed; at transmission electron microscopy, instead, it was possible to observe that T gangliar cells contained an abnormal abundant smooth reticulum with enlarged cisternae and numerous vacuoles; myelinated axons presented pathological features and their myelin coverage was not adherent. Instead, unmyelinated axons appeared normal in shape and dimension and the Schwann cells surrounding it had intact plasmamembrane. Our results, obtained at acute stage, reveal that the PRF procedure should destroy the myelin envelope of nervous fibres. Further future studies, at chronic stage, should give other information on the prognosis of the myelinic damage. PMID:19172311

  4. Application of radiofrequency thermocoagulation combined with adriamycin injection in dorsal root ganglia for controlling refractory pain induced by rib metastasis of lung cancer (a STROBE-compliant article)

    PubMed Central

    Xie, Guang-lun; Guo, Da-peng; Li, Zhi-gang; Liu, Chang; Zhang, Wei

    2016-01-01

    Abstract This study aimed to observe the therapeutic effects and adverse reactions of radiofrequency thermocoagulation combined with adriamycin injection in dorsal root ganglia on lung cancer rib metastasis-related refractory pain which has no response to conventional therapy. This study contained 27 patients with lung cancer rib metastasis-related moderate or severe pain which had no response to conventional therapy. Under computed tomography (CT)-guidance, radiofrequency puncture need reached the corresponding intervertebral foramens to ensure needle point near dorsal root ganglia (DRG) by sensory and motor stimulation tests, and then radiofrequency thermocoagulation was performed on each corresponding DRG followed by injection of 0.5 to 1 mL of adriamycin (0.5%). The conditions of pain and complications were observed before management and 3 days, 1 month, and 3 months after management, respectively. Numerical rating scale (NRS) scores and dosage of morphine were all significantly decreased after management as compared with those before management (all P < 0.01). Although the number of patients with chest wall numbness was significantly increased after management as compared with that before management (all P < 0.01), the degree of chest wall numbness was tolerable. There were no statistical differences between before and after management in nausea and vomiting, and constipation. CT-guided radiofrequency thermocoagulation combined with adriamycin injection in DRG can effectively control lung cancer rib metastasis-related pain which has no response to conventional therapy. This combinatory treatment regimen is featured by better therapeutic effects and a few complications, so it is worthy of being recommended in clinical application. PMID:27749531

  5. N-acetyl-cysteine attenuates remifentanil-induced postoperative hyperalgesia via inhibiting matrix metalloproteinase-9 in dorsal root ganglia

    PubMed Central

    Zhang, Wei; Sun, Yu-E; Ma, Zhengliang; Gu, Xiaoping

    2017-01-01

    Treatment of remifentanil-induced postoperative hyperalgesia (RIH) remains a clinical challenge because the mechanisms are not fully understood. Matrix metalloproteinase-9 (MMP-9) is a key component in neuroinflammation because of its facilitation of pro-inflammatory cytokine maturation. Therefore, inhibition of MMP-9 may represent a novel therapeutic approach to the treatment of RIH. Sprague-Dawley rats were randomly divided into three groups: Control, Incision and Remifentanil. A right plantar surgical incision was performed in Group Incision, and intraoperative remifentanil (0.04 mg/kg, 0.4 ml) was infused subcutaneously for 30 min in Group Remifentanil. The results indicated that intraoperative remifentanil induced an up-regulation and activation of MMP-9 in DRGs but not spinal cords. MMP-9 was expressed primarily in DRG neurons co-expressing mu opioid receptors (MOR), and elicited interleukin-1β (IL-1β) cleavage in DRG neurons and satellite glial cells (SGCs). Intraperitoneal injection of N-acetyl-cysteine (NAC), a broadly used safe drug, significantly attenuated RIH via suppressing the activation of MMP-9 in DRGs. NAC inhibited the cleavage of IL-1β in DRGs, which is a critical substrate of MMP-9, and markedly suppressed glial activation and neuron excitability in spinal dorsal horn induced by remifentanil. These results demonstrated that NAC can effectively alleviate RIH via powerfully inhibiting MMP-9 activation in DRGs. PMID:28199982

  6. N-acetyl-cysteine attenuates remifentanil-induced postoperative hyperalgesia via inhibiting matrix metalloproteinase-9 in dorsal root ganglia.

    PubMed

    Liu, Yue; Ni, Yuan; Zhang, Wei; Sun, Yu-E; Ma, Zhengliang; Gu, Xiaoping

    2017-02-09

    Treatment of remifentanil-induced postoperative hyperalgesia (RIH) remains a clinical challenge because the mechanisms are not fully understood. Matrix metalloproteinase-9 (MMP-9) is a key component in neuroinflammation because of its facilitation of pro-inflammatory cytokine maturation. Therefore, inhibition of MMP-9 may represent a novel therapeutic approach to the treatment of RIH. Sprague-Dawley rats were randomly divided into three groups: Control, Incision and Remifentanil. A right plantar surgical incision was performed in Group Incision, and intraoperative remifentanil (0.04 mg/kg, 0.4 ml) was infused subcutaneously for 30 min in Group Remifentanil. The results indicated that intraoperative remifentanil induced an up-regulation and activation of MMP-9 in DRGs but not spinal cords. MMP-9 was expressed primarily in DRG neurons co-expressing mu opioid receptors (MOR), and elicited interleukin-1β (IL-1β) cleavage in DRG neurons and satellite glial cells (SGCs). Intraperitoneal injection of N-acetyl-cysteine (NAC), a broadly used safe drug, significantly attenuated RIH via suppressing the activation of MMP-9 in DRGs. NAC inhibited the cleavage of IL-1β in DRGs, which is a critical substrate of MMP-9, and markedly suppressed glial activation and neuron excitability in spinal dorsal horn induced by remifentanil. These results demonstrated that NAC can effectively alleviate RIH via powerfully inhibiting MMP-9 activation in DRGs.

  7. Reconstructing Norms

    ERIC Educational Resources Information Center

    Gorgorio, Nuria; Planas, Nuria

    2005-01-01

    Starting from the constructs "cultural scripts" and "social representations", and on the basis of the empirical research we have been developing until now, we revisit the construct norms from a sociocultural perspective. Norms, both sociomathematical norms and norms of the mathematical practice, as cultural scripts influenced…

  8. Dorsal root ganglion neurons become hyperexcitable and increase expression of voltage-gated T-type calcium channels (Cav3.2) in paclitaxel-induced peripheral neuropathy.

    PubMed

    Li, Yan; Tatsui, Claudio Esteves; Rhines, Laurence D; North, Robert Y; Harrison, Daniel S; Cassidy, Ryan M; Johansson, Caj A; Kosturakis, Alyssa K; Edwards, Denaya D; Zhang, Hongmei; Dougherty, Patrick M

    2017-03-01

    Here, it is shown that paclitaxel-induced neuropathy is associated with the development of spontaneous activity (SA) and hyperexcitability in dorsal root ganglion (DRG) neurons that is paralleled by increased expression of low-voltage-activated calcium channels (T-type; Cav3.2). The percentage of DRG neurons showing SA and the overall mean rate of SA were significantly higher at day 7 in rats receiving paclitaxel treatment than in rats receiving vehicle. Cav3.2 expression was increased in L4-L6 DRG and spinal cord segments in paclitaxel-treated rats, localized to small calcitonin gene-related peptide and isolectin B4 expressing DRG neurons and to glial fibrillary acidic protein-positive spinal cord cells. Cav3.2 expression was also co-localized with toll-like receptor 4 (TLR4) in both the DRG and the dorsal horn. T-type current amplitudes and density were increased at day 7 after paclitaxel treatment. Perfusion of the TLR4 agonist lipopolysaccharide directly activated DRG neurons, whereas this was prevented by pretreatment with the specific T-type calcium channel inhibitor ML218 hydrochloride. Paclitaxel-induced behavioral hypersensitivity to mechanical stimuli in rats was prevented but not reversed by spinal administration of ML218 hydrochloride or intravenous injection of the TLR4 antagonist TAK242. Paclitaxel induced inward current and action potential discharges in cultured human DRG neurons, and this was blocked by ML218 hydrochloride pretreatment. Furthermore, ML218 hydrochloride decreased firing frequency in human DRG, where spontaneous action potentials were present. In summary, Cav3.2 in concert with TLR4 in DRG neurons appears to contribute to paclitaxel-induced neuropathy.

  9. Spinal nerve ligation decreases γ-aminobutyric acidB receptors on specific populations of immunohistochemically identified neurons in L5 dorsal root ganglion of the rat.

    PubMed

    Engle, Mitchell P; Merrill, Michelle A; Marquez De Prado, Blanca; Hammond, Donna L

    2012-06-01

    This study examined the distribution of γ-aminobutyric acid (GABA)(B) receptors on immunohistochemically identified neurons, and levels of GABA(B(1)) and GABA(B(2)) mRNA, in the L4 and L5 dorsal root ganglia (DRG) of the rat in the absence of injury and 2 weeks after L5 spinal nerve ligation. In uninjured DRG, GABA(B(1)) immunoreactivity colocalized exclusively with the neuronal marker (NeuN) and did not colocalize with the satellite cell marker S-100. The GABA(B(1)) subunit colocalized to >97% of DRG neurons immunoreactive (IR) for neurofilament 200 (N52) or calcitonin gene-related peptide (CGRP), or labeled by isolectin B4 (IB4). Immunoreactivity for GABA(B(2)) was not detectable. L5 spinal nerve ligation did not alter the number of GABA(B(1)) -IR neurons or its colocalization pattern in the L4 DRG. However, ligation reduced the number of GABA(B(1)) -IR neurons in the L5 DRG by ≈38% compared with sham-operated and naïve rats. Specifically, ligation decreased the number of CGRP-IR neurons in the L5 DRG by 75%, but did not decrease the percent colocalization of GABA(B(1)) in those that remained. In the few IB4-positive neurons that remained in the L5 DRG, colocalization of GABA(B(1)) -IR decreased to 75%. Ligation also decreased levels of GABA(B(1)) and GABA(B(2)) mRNA in the L5, but not the L4 DRG compared with sham-operated or naïve rats. These findings indicate that the GABA(B) receptor is positioned to presynaptically modulate afferent transmission by myelinated, unmyelinated, and peptidergic afferents in the dorsal horn. Loss of GABA(B) receptors on primary afferent neurons may contribute to the development of mechanical allodynia after L5 spinal nerve ligation.

  10. Upregulation of adrenomedullin in the spinal cord and dorsal root ganglia in the early phase of CFA-induced inflammation in rats.

    PubMed

    Hong, Yanguo; Liu, Yushan; Chabot, Jean-Guy; Fournier, Alain; Quirion, Rémi

    2009-11-01

    Adrenomedullin (AM), a member of calcitonin gene-related peptide (CGRP) family, has been demonstrated to be a pronociceptive mediator [28]. This study was undertaken to investigate the role of AM in a model of complete Freund's adjuvant (CFA)-induced inflammatory pain. Injection of CFA, but not of saline, in the unilateral hindpaw produced an increase in the expression of AM-like immunoreactivity (AM-IR) in laminae I-II of the spinal cord as well as in small- and medium-sized dorsal root ganglion (DRG) neurons at 48 h. The content of AM in DRG on the side ipsilateral to CFA injection started to increase at 4 h and remained at high levels at 24 and 48 h. The selective antagonist of AM receptors, AM(22-52), administered intrathecally (i.t.) 24 h after CFA injection inhibited inflammation-associated hyperalgesia in a dose-dependent manner (2, 5 and 10 nmol). Impressively, this anti-hyperalgesic effect lasted for at least 24 h. I.t. administration of AM(22-52) (10 nmol) also reversed CFA-induced increase in AM-IR in the spinal dorsal horn and DRG. Furthermore, blockade of AM receptors abolished CFA-induced changes in the expression and content of CGRP-like immunoreactivity in these regions. Taken together, our results suggest that the upregulation of AM in DRG neurons contributes to the development of inflammatory pain, and this effect is mediated, at least in part, by enhancing the expression and release of CGRP. Blocking AM receptor downstream signaling effects using antagonists has the potential of relieving pain following the induction of inflammation.

  11. Primary afferent neurons containing calcitonin gene-related peptide but not substance P in forepaw skin, dorsal root ganglia, and spinal cord of mice.

    PubMed

    Kestell, Garreth R; Anderson, Rebecca L; Clarke, Jennifer N; Haberberger, Rainer V; Gibbins, Ian L

    2015-12-01

    In mice dorsal root ganglia (DRG), some neurons express calcitonin gene-related peptide (CGRP) without substance P (SP; CGRP(+) SP(-) ). The projections and functions of these neurons are unknown. Therefore, we combined in vitro axonal tracing with multiple-labeling immunohistochemistry to neurochemically define these neurons and characterize their peripheral and central projections. Cervical spinal cord, DRG, and forepaw skin were removed from C57Bl/6 mice and multiple-labeled for CGRP, SP, and either marker for the sensory neuron subpopulations transient receptor potential vanilloid type 1 (TRPV1), neurofilament 200 (NF200), or vesicular glutamate transporter 2 (VGluT1). To determine central projections of CGRP(+) SP(-) neurons, Neurobiotin (NB) was applied to the C7 ventral ramus and visualized in DRG and spinal cord sections colabeled for CGRP and SP. Half (50%) of the CGRP-immunoreactive DRG neurons lacked detectable SP and had a mean soma size of 473 ± 14 μm(2) (n = 5); 89% of the CGRP(+) SP(-) neurons expressed NF200 (n = 5), but only 32% expressed TRPV1 (n = 5). Cutaneous CGRP(+) SP(-) fibers were numerous within dermal papillae and around hair shafts (n = 4). CGRP(+) SP(-) boutons were prevalent in lateral lamina I and in lamina IV/V of the dorsal horn (n = 5). NB predominantly labeled fibers penetrating lamina IV/V, 6 ± 3% contained CGRP (n = 5), and 21 ± 2% contained VGluT1 (n = 3). CGRP(+) SP(-) afferent neurons are likely to be non-nociceptive. Their soma size, neurochemical profile, and peripheral and central targets suggest that CGRP(+) SP(-) neurons are polymodal mechanoceptors. © 2015 Wiley Periodicals, Inc.

  12. Neonatal intraperitoneal or intravenous injections of recombinant adeno-associated virus type 8 transduce dorsal root ganglia and lower motor neurons.

    PubMed

    Foust, Kevin D; Poirier, Amy; Pacak, Christina A; Mandel, Ronald J; Flotte, Terence R

    2008-01-01

    Targeting lower motor neurons (LMNs) for gene delivery could be useful for disorders such as spinal muscular atrophy and amyotrophic lateral sclerosis. LMNs reside in the ventral gray matter of the spinal cord and send axonal projections to innervate skeletal muscle. Studies have used intramuscular injections of adeno-associated virus type 2 (AAV2) to deliver viral vectors to LMNs via retrograde transport. However, treating large areas of the spinal cord in a human would require numerous intramuscular injections, thereby increasing viral titer and risk of immune response. New AAV serotypes, such as AAV8, have a dispersed transduction pattern after intravenous or intraperitoneal injection in neonatal mice, and may transduce LMNs by retrograde transport or through entry into the nervous system. To test LMN transduction after systemic injection, we administered recombinant AAV8 (rAAV8) carrying the green fluorescent protein (GFP) gene by intravenous or intraperitoneal injection to neonatal mice on postnatal day 1. Tissues were harvested 5 and 14 days postinjection and analyzed by real-time polymerase chain reaction and GFP immunohistochemistry to assess the presence of AAV genomes and GFP expression, respectively. Spinal cords were positive for AAV genomes at both time points. GFP immunohistochemistry revealed infrequent labeling of LMNs across all time points and injection routes. Somewhat surprisingly, there was extensive labeling of fibers in the dorsal horns and columns, indicating dorsal root ganglion transduction across all time points and injection routes. Our data suggest that systemic injection of rAAV8 is not an effective delivery route to target lower motor neurons, but could be useful for targeting sensory pathways in chronic pain.

  13. Minocycline reduces the injury-induced expression of prodynorphin and pronociceptin in the dorsal root ganglion in a rat model of neuropathic pain.

    PubMed

    Mika, J; Rojewska, E; Makuch, W; Przewlocka, B

    2010-02-17

    A role of neuropeptides in neuropathic pain development has been implicated; however, the neuroimmune interactions that are involved in the underlying mechanisms may be more important than previously thought. To examine a potential role of relations between glia cells and neuropeptides in neuropathic pain, we performed competitive reverse-transcription polymerase chain reaction (RT-PCR) from the dorsal lumbar spinal cord and the dorsal root ganglion (DRG) after chronic constriction injury (CCI) in the rat sciatic nerve. The RT-PCR results indicated that complement component 1, q subcomponent (C1q) mRNA expression was higher than glial fibrillary acidic protein (GFAP) in the spinal cord 3 and 7 days post-CCI, suggesting that spinal microglia and perivascular macrophages are more activated than astrocytes. In parallel, we observed a strong upregulation of prodynorphin mRNA in the spinal cord after CCI, with no changes in the expression of proenkephalin or pronociceptin. Conversely, the expression of GFAP mRNA in the DRG was higher than C1q, which suggests that the satellite cells are activated shortly after injury, followed by the macrophages and polymorphonuclear leukocytes infiltrating the DRG. In the DRG, we also observed a very strong upregulation of prodynorphin (1387%) as well as pronociceptin (122%) and a downregulation of proenkephalin (47%) mRNAs. Interestingly, preemptive and repeated i.p. injection of minocycline reversed the activation of microglia/macrophages in the spinal cord and the trafficking of peripheral immune cells into the DRG, and markedly diminished the upregulation of prodynorphin and pronociceptin in the DRG. We thus provide novel findings that inhibition of C1q-positive cells by minocycline can diminish injury-induced neuropeptide changes in the DRG. This suggests that immune cells-derived pronociceptive factors may influence opioid peptide expression. Therefore, the injury-induced activation of microglia and leukocytes and the subsequent

  14. Up-regulation of dorsal root ganglia BDNF and trkB receptor in inflammatory pain: an in vivo and in vitro study

    PubMed Central

    2011-01-01

    Background During inflammation, immune cells accumulate in damaged areas and release pro-inflammatory cytokines and neurotrophins. Brain-derived neurotrophic factor (BDNF) plays a neuromodulatory role in spinal cord dorsal horn via the post-synaptic tyrosine protein kinase B (trkB) receptor to facilitate pain transmission. However, the precise role of BDNF and trkB receptor in the primary sensory neurons of dorsal root ganglia (DRG) during inflammation remains to be clarified. The aim of this study was to investigate whether and how BDNF-trkB signaling in the DRG is involved in the process of inflammatory pain. Methods We used complete Freund's adjuvant- (CFA-) induced and tumor necrosis factor-α- (TNF-α-) induced inflammation in rat hindpaw as animal models of inflammatory pain. Quantification of protein and/or mRNA levels of pain mediators was performed in separate lumbar L3-L5 DRGs. The cellular mechanism of TNF-α-induced BDNF and/or trkB receptor expression was examined in primary DRG cultures collected from pooled L1-L6 DRGs. Calcitonin gene-related peptide (CGRP), BDNF and substance P release were also evaluated by enzyme immunoassay. Results CFA injection into rat hindpaw resulted in mechanical hyperalgesia and significant increases in levels of TNF-α in the inflamed tissues, along with enhancement of BDNF and trkB receptor as well as the pain mediators CGRP and transient receptor potential vanilloid receptor subtype 1 (TRPV1) in DRG. Direct injection of TNF-α into rat hindpaw resulted in similar effects with retrograde transport of TNF-α along the saphenous nerve to DRG during CFA-induced inflammation. Primary DRG cultures chronically treated with TNF-α showed significant enhancement of mRNA and protein levels of BDNF and trkB receptor, BDNF release and trkB-induced phospho-ERK1/2 signal. Moreover, CGRP and substance P release were enhanced in DRG cultures after chronic TNF-α treatment or acute BDNF stimulation. In addition, we found that BDNF up

  15. Functional coupling, desensitization and internalization of virally expressed mu opioid receptors in cultured dorsal root ganglion neurons from mu opioid receptor knockout mice.

    PubMed

    Walwyn, W M; Keith, D E; Wei, W; Tan, A M; Xie, C W; Evans, C J; Kieffer, B L; Maidment, N T

    2004-01-01

    Although mu opioid receptors desensitize in various cell lines in vitro, the relationship of this change in signaling efficacy to the development of tolerance in vivo remains uncertain. It is clear that a system is needed in which functional mu opioid receptor expression is obtained in appropriate neurons so that desensitization can be measured, manipulated, and mutated receptors expressed in this environment. We have developed a recombinant system in which expression of a flag-tagged mu opioid receptor is returned to dorsal root ganglia neurons from mu opioid receptor knockout mice in vitro. Flow cytometry analysis showed that adenoviral-mediated expression of the amino-terminal flag-tagged mu opioid receptor in neurons resulted in approximately 1.3x10(6) receptors/cell. Many mu opioid receptor cell lines express a similar density of receptors but this is approximately 7x greater than the number of endogenous receptors expressed by matched wild-type neurons. Inhibition of the high voltage-activated calcium currents in dorsal root ganglia neurons by the mu agonist, D-Ala(2), N-MePhe(4), Gly(5)-ol-enkephalin (DAMGO), was not different between the endogenous and flag-tagged receptor at several concentrations of DAMGO used. Both receptors desensitized equally over the first 6 h of DAMGO pre-incubation, but after 24 h the response of the endogenous receptor to DAMGO had desensitized further than the flag- tagged receptor (71+/-3 vs 29+/-7% respectively; P<0.002), indicating less desensitization in neurons expressing a higher density of receptor. Using flow cytometry to quantify the percentage of receptors remaining on the neuronal cell surface, the flag-tagged receptor internalized by 17+/-1% after 20 min and 55+/-2% after 24 h of DAMGO. These data indicate that this return of function model in neurons recapitulates many of the characteristics of endogenous mu opioid receptor function previously identified in non-neuronal cell lines.

  16. Sodium channel Nav1.7 expression is upregulated in the dorsal root ganglia in a rat model of paclitaxel-induced peripheral neuropathy.

    PubMed

    Xia, Zhongyuan; Xiao, Yun; Wu, Yang; Zhao, Bo

    2016-01-01

    Paclitaxel-induced peripheral neuropathy is not completely known. Since the sodium channel Nav1.7 has been implicated in pain perception, and is upregulated in pain disorders, we investigated the effect of paclitaxel on Nav1.7 expression in rat dorsal root ganglion (DRG) neurons. Thirty Sprague-Dawley rats were administered either 2 mg/kg paclitaxel or vehicle on days 0, 2, 4 and 6. To evaluate nociceptive responses, paw withdrawal threshold (PWT) was measured by von Frey anesthesiometer on days 7, 14 and 21 after first paclitaxel administration. Expression of Nav1.7 in DRG was measured by real-time RT-PCR and Western blot. PWT was also measured in rats that received dorsal root ganglionic injection of either Nav1.7 antibody, neutralized Nav1.7 antibody or no injection (sham surgery) (n = 5/group). Average PWT was lower in animals administered paclitaxel than those administered vehicle at days 7 (P < 0.05), 14 (P < 0.01), and 21 (P < 0.01). DRG Nav1.7 mRNA and protein levels were higher in animals administered paclitaxel than those administered vehicle on days 7, 14 and 21 (all P < 0.05). PWT decrease was significantly correlated with increased Nav1.7 protein levels on days 7 (r = -0.88, P = 0.04), 14 (r = -0.46, P = 0.03) and 21 (r = -0.27, P = 0.01) after first paclitaxel administration. In animals that received sham surgery, neutralized Nav1.7 antibody or Nav1.7 antibody, PWTs were significantly reduced 7 days after first paclitaxel administration (all P < 0.05), but PWTs of animals that received Nav1.7 antibody were higher than those that received neutralized Nav1.7 antibody (P < 0.05). These results indicate that increased DRG Nav1.7 expression may be partially responsible for paclitaxel-induced peripheral neuropathy.

  17. Effects of niflumic acid on γ-aminobutyric acid-induced currents in isolated dorsal root ganglion neurons of neuropathic pain rats.

    PubMed

    Wang, Li-Jie; Wang, Yang; Chen, Meng-Jie; Tian, Zhen-Pu; Lu, Bi-Han; Mao, Ke-Tao; Zhang, Liang; Zhao, Lei; Shan, Li-Ya; Li, Li; Si, Jun-Qiang

    2017-08-01

    Niflumic acid (NFA) is a type of non-steroidal anti-inflammatory drug. Neuropathic pain is caused by a decrease in presynaptic inhibition mediated by γ-aminobutyric acid (GABA). In the present study, a whole-cell patch-clamp technique and intracellular recording were used to assess the effect of NFA on GABA-induced inward current in dorsal root ganglion (DRG) neurons of a chronic constriction injury (CCI) model. It was observed that 1-1,000 µmol/l GABA induced a concentration-dependent inward current in DRG neurons. Compared with pseudo-operated rats, the thermal withdrawal latency (TWL) of CCI rats significantly decreased (P<0.01); however, the TWLs of each NFA group (50 and 300 µmol/l) were significantly longer than that of the CCI group (P<0.01). In the CCI group, the response evoked by GABA (10(-6)-10(-3) mol/l) was reduced in a concentration dependent manner compared with a normal control group (P<0.01), and the current amplitudes of CCI rats activated by the same concentrations of GABA (10(-6)-10(-3) mol/l) were significantly decreased compared with the control group (P<0.05). The inward currents activated by 100 µmol/l GABA were suppressed by treatment with 1, 10 and 100 µmol/l NFA (5.32±3.51, 33.8±5.20, and 52.2±6.32%, respectively; P<0.05). The inverse potentials of GABA-induced currents were 9.87±1.32 and 9.64±1.24 mV with and without NFA, respectively (P<0.05). Pre-treatment with NFA exerted a strong inhibitory effect on the peak value of GABA-induced current, and the GABA-induced response was inhibited by the same concentrations of NFA (1, 10 and 100 µmol/l) in the control and CCI groups (P<0.05). The results suggest that NFA reduced the primary afferent depolarization (PAD) associated with neuropathic pain and mediated by the GABAA receptor. NFA may regulate neuropathic pain by inhibiting dorsal root reflexes, which are triggered PAD.

  18. Effects of niflumic acid on γ-aminobutyric acid-induced currents in isolated dorsal root ganglion neurons of neuropathic pain rats

    PubMed Central

    Wang, Li-Jie; Wang, Yang; Chen, Meng-Jie; Tian, Zhen-Pu; Lu, Bi-Han; Mao, Ke-Tao; Zhang, Liang; Zhao, Lei; Shan, Li-Ya; Li, Li; Si, Jun-Qiang

    2017-01-01

    Niflumic acid (NFA) is a type of non-steroidal anti-inflammatory drug. Neuropathic pain is caused by a decrease in presynaptic inhibition mediated by γ-aminobutyric acid (GABA). In the present study, a whole-cell patch-clamp technique and intracellular recording were used to assess the effect of NFA on GABA-induced inward current in dorsal root ganglion (DRG) neurons of a chronic constriction injury (CCI) model. It was observed that 1–1,000 µmol/l GABA induced a concentration-dependent inward current in DRG neurons. Compared with pseudo-operated rats, the thermal withdrawal latency (TWL) of CCI rats significantly decreased (P<0.01); however, the TWLs of each NFA group (50 and 300 µmol/l) were significantly longer than that of the CCI group (P<0.01). In the CCI group, the response evoked by GABA (10−6-10−3 mol/l) was reduced in a concentration dependent manner compared with a normal control group (P<0.01), and the current amplitudes of CCI rats activated by the same concentrations of GABA (10−6-10−3 mol/l) were significantly decreased compared with the control group (P<0.05). The inward currents activated by 100 µmol/l GABA were suppressed by treatment with 1, 10 and 100 µmol/l NFA (5.32±3.51, 33.8±5.20, and 52.2±6.32%, respectively; P<0.05). The inverse potentials of GABA-induced currents were 9.87±1.32 and 9.64±1.24 mV with and without NFA, respectively (P<0.05). Pre-treatment with NFA exerted a strong inhibitory effect on the peak value of GABA-induced current, and the GABA-induced response was inhibited by the same concentrations of NFA (1, 10 and 100 µmol/l) in the control and CCI groups (P<0.05). The results suggest that NFA reduced the primary afferent depolarization (PAD) associated with neuropathic pain and mediated by the GABAA receptor. NFA may regulate neuropathic pain by inhibiting dorsal root reflexes, which are triggered PAD. PMID:28810599

  19. Dorsal root tetrodotoxin-resistant sodium channels do not contribute to the augmented exercise pressor reflex in rats with chronic femoral artery occlusion

    PubMed Central

    McCord, Jennifer L.; Leal, Anna K.; Kaufman, Marc P.

    2011-01-01

    We investigated the contribution of tetrodotoxin (TTX)-resistant sodium channels to the augmented exercise pressor reflex observed in decerebrated rats with femoral artery ligation. The pressor responses to static contraction, to tendon stretch, and to electrical stimulation of the tibial nerve were compared before and after blocking TTX-sensitive sodium channels on the L3-L6 dorsal roots of rats whose hindlimbs were freely perfused and rats whose femoral arteries were ligated 72 h before the start of the experiment. In the freely perfused group (n = 9), pressor (Δ22 ± 4 mmHg) and cardioaccelerator (Δ32 ± 6 beats/min) responses to contraction were attenuated by 1 μM TTX (Δ4 ± 1 mmHg, P < 0.05 and Δ17 ± 4 beats/min, P < 0.05, respectively). In the 72 h ligated group (n = 9), the augmented pressor response to contraction (32 ± 4 mmHg) was also attenuated by 1 μM TTX (Δ8 ± 2 mmHg, P < 0.05). The cardioaccelerator response to contraction was not significantly attenuated in these rats. In addition, TTX suppressed the pressor response to tendon stretch in both groups of rats. Electrical stimulation of the tibial nerve evoked similar pressor responses between the two groups (freely perfused: Δ74 ± 9 mmHg and 72 h ligated: Δ78 ± 5 mmHg). TTX attenuated the pressor response to the tibial nerve stimulation by about one-half in both groups. Application of the TTX-resistant sodium channel blocker A-803467 (1 μM) with TTX (1 μM) did not block the pressor response to tibial nerve stimulation to any greater extent than did application of TTX (1 μM) alone. Although the contribution of TTX-resistant sodium channels to the augmented exercise pressor reflex may be slightly increased in rats with chronic femoral artery ligation, TTX-resistant sodium channels on dorsal roots do not play a major role in the augmented exercise pressor reflex. PMID:21076028

  20. TRPV1 channels are functionally coupled with BK(mSlo1) channels in rat dorsal root ganglion (DRG) neurons.

    PubMed

    Wu, Ying; Liu, Yongfeng; Hou, Panpan; Yan, Zonghe; Kong, Wenjuan; Liu, Beiying; Li, Xia; Yao, Jing; Zhang, Yuexuan; Qin, Feng; Ding, Jiuping

    2013-01-01

    The transient receptor potential vanilloid receptor 1 (TRPV1) channel is a nonselective cation channel activated by a variety of exogenous and endogenous physical and chemical stimuli, such as temperature (≥42 °C), capsaicin, a pungent compound in hot chili peppers, and allyl isothiocyanate. Large-conductance calcium- and voltage-activated potassium (BK) channels regulate the electric activities and neurotransmitter releases in excitable cells, responding to changes in membrane potentials and elevation of cytosolic calcium ions (Ca(2+)). However, it is unknown whether the TRPV1 channels are coupled with the BK channels. Using patch-clamp recording combined with an infrared laser device, we found that BK channels could be activated at 0 mV by a Ca(2+) influx through TRPV1 channels not the intracellular calcium stores in submilliseconds. The local calcium concentration around BK is estimated over 10 μM. The crosstalk could be affected by 10 mM BAPTA, whereas 5 mM EGTA was ineffectual. Fluorescence and co-immunoprecipitation experiments also showed that BK and TRPV1 were able to form a TRPV1-BK complex. Furthermore, we demonstrated that the TRPV1-BK coupling also occurs in dosal root ganglion (DRG) cells, which plays a critical physiological role in regulating the "pain" signal transduction pathway in the peripheral nervous system.

  1. TRPV1 Channels Are Functionally Coupled with BK(mSlo1) Channels in Rat Dorsal Root Ganglion (DRG) Neurons

    PubMed Central

    Yan, Zonghe; Kong, Wenjuan; Liu, Beiying; Li, Xia; Yao, Jing; Zhang, Yuexuan; Qin, Feng; Ding, Jiuping

    2013-01-01

    The transient receptor potential vanilloid receptor 1 (TRPV1) channel is a nonselective cation channel activated by a variety of exogenous and endogenous physical and chemical stimuli, such as temperature (≥42 °C), capsaicin, a pungent compound in hot chili peppers, and allyl isothiocyanate. Large-conductance calcium- and voltage-activated potassium (BK) channels regulate the electric activities and neurotransmitter releases in excitable cells, responding to changes in membrane potentials and elevation of cytosolic calcium ions (Ca2+). However, it is unknown whether the TRPV1 channels are coupled with the BK channels. Using patch-clamp recording combined with an infrared laser device, we found that BK channels could be activated at 0 mV by a Ca2+ influx through TRPV1 channels not the intracellular calcium stores in submilliseconds. The local calcium concentration around BK is estimated over 10 μM. The crosstalk could be affected by 10 mM BAPTA, whereas 5 mM EGTA was ineffectual. Fluorescence and co-immunoprecipitation experiments also showed that BK and TRPV1 were able to form a TRPV1-BK complex. Furthermore, we demonstrated that the TRPV1-BK coupling also occurs in dosal root ganglion (DRG) cells, which plays a critical physiological role in regulating the “pain” signal transduction pathway in the peripheral nervous system. PMID:24147119

  2. Attenuation of pain behaviour by local administration of alpha-2 adrenoceptor antagonists to dorsal root ganglia in a rat radiculopathy model.

    PubMed

    Ogon, I; Takebayashi, T; Miyakawa, T; Iwase, T; Tanimoto, K; Terashima, Y; Jimbo, S; Kobayashi, T; Tohse, N; Yamashita, T

    2016-05-01

    There were several reports suggesting α-adrenoceptor antagonists are effective to treat neuropathic pain. The aims of this study were as follows: (1) to introduce drug delivery system for dorsal root ganglion (DRG) neurons; (2) to elucidate the effects of α-adrenoceptor antagonists in acute, subacute or chronic phase and (3) to determine which subtype of adrenoceptor was mainly involved. We used 130 male Sprague-Dawley rats. After root constriction, rats received three local injections of α-adrenoceptor antagonists around DRG. We administered the non-selective α-adrenoceptor antagonist phentolamine for 3 consecutive days from day 0, 4 or 11 after the surgery, and the α1-adrenoceptor antagonist prazosin, the α1-adrenoceptor antagonist silodosin, the more preferred α1-adrenoceptor than prazosin and the α2-adrenoceptor antagonist yohimbine for 3 consecutive days from day 0 after the surgery. Phentolamine and yohimbine continually attenuated pain behaviour. Prazosin at high dose attenuated pain behaviour, however, prazosin at low dose did not attenuate pain behaviour every experimental day. Silodosin had no analgesic effect. Phentolamine injections from day 4 after surgery attenuated pain behaviour that had been established on the 3rd experimental day until the 28th post-operative day, although effect of phentolamine wore off. Phentolamine injections from day 11 after surgery temporarily attenuated pain behaviour that had been established on the 3rd, 7th and 10th experimental days. This study showed α-adrenoceptor antagonists could suppress pain behaviour via α2-adrenoceptor in acute phase and temporary attenuate pain behaviour in chronic phase. These findings presented potentials sympathetic nerve blockade contributed to treat neuropathic pain. © 2015 European Pain Federation - EFIC®

  3. Gene Therapy for Neuropathic Pain by Silencing of TNF-α Expression with Lentiviral Vectors Targeting the Dorsal Root Ganglion in Mice

    PubMed Central

    Ogawa, Nobuhiro; Kawai, Hiromichi; Terashima, Tomoya; Kojima, Hideto; Oka, Kazuhiro; Chan, Lawrence; Maegawa, Hiroshi

    2014-01-01

    Neuropathic pain can be a debilitating condition. Many types of drugs that have been used to treat neuropathic pain have only limited efficacy. Recent studies indicate that pro-inflammatory mediators including tumor necrosis factor α (TNF-α) are involved in the pathogenesis of neuropathic pain. In the present study, we engineered a gene therapy strategy to relieve neuropathic pain by silencing TNF-α expression in the dorsal root ganglion (DRG) using lentiviral vectors expressing TNF short hairpin RNA1-4 (LV-TNF-shRNA1-4) in mice. First, based on its efficacy in silencing TNF-α in vitro, we selected shRNA3 to construct LV-TNF-shRNA3 for in vivo study. We used L5 spinal nerve transection (SNT) mice as a neuropathic pain model. These animals were found to display up-regulated mRNA expression of activating transcription factor 3 (ATF3) and neuropeptide Y (NPY), injury markers, and interleukin (IL)-6, an inflammatory cytokine in the ipsilateral L5 DRG. Injection of LV-TNF-shRNA3 onto the proximal transected site suppressed significantly the mRNA levels of ATF3, NPY and IL-6, reduced mechanical allodynia and neuronal cell death of DRG neurons. These results suggest that lentiviral-mediated silencing of TNF-α in DRG relieves neuropathic pain and reduces neuronal cell death, and may constitute a novel therapeutic option for neuropathic pain. PMID:24642694

  4. A Novel Carbamoyloxy Arylalkanoyl Arylpiperazine Compound (SKL-NP) Inhibits Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) Channel Currents in Rat Dorsal Root Ganglion Neurons.

    PubMed

    Chung, Gehoon; Kim, Tae-Hyung; Shin, Hyewon; Chae, Eunhee; Yi, Hanju; Moon, Hongsik; Kim, Hyun Jin; Kim, Joong Soo; Jung, Sung Jun; Oh, Seog Bae

    2012-08-01

    In this study, we determined mode of action of a novel carbamoyloxy arylalkanoyl arylpiperazine compound (SKL-NP) on hyperpolarization-activated cyclic nucleotide-gated (HCN) channel currents (I(h)) that plays important roles in neuropathic pain. In small or medium-sized dorsal root ganglion (DRG) neurons (<40 µm in diameter) exhibiting tonic firing and prominent I(h), SKL-NP inhibited I(h) and spike firings in a concentration dependent manner (IC(50)=7.85 µM). SKL-NP-induced inhibition of I(h) was blocked by pretreatment of pertussis toxin (PTX) and N-ethylmaleimide (NEM) as well as 8-Br-cAMP, a membrane permeable cAMP analogue. These results suggest that SKL-NP modulates I(h) in indirect manner by the activation of a Gi-protein coupled receptor that decreases intracellular cAMP concentration. Taken together, SKL-NP has the inhibitory effect on HCN channel currents (I(h)) in DRG neurons of rats.

  5. Neuro-fuzzy decoding of sensory information from ensembles of simultaneously recorded dorsal root ganglion neurons for functional electrical stimulation applications

    NASA Astrophysics Data System (ADS)

    Rigosa, J.; Weber, D. J.; Prochazka, A.; Stein, R. B.; Micera, S.

    2011-08-01

    Functional electrical stimulation (FES) is used to improve motor function after injury to the central nervous system. Some FES systems use artificial sensors to switch between finite control states. To optimize FES control of the complex behavior of the musculo-skeletal system in activities of daily life, it is highly desirable to implement feedback control. In theory, sensory neural signals could provide the required control signals. Recent studies have demonstrated the feasibility of deriving limb-state estimates from the firing rates of primary afferent neurons recorded in dorsal root ganglia (DRG). These studies used multiple linear regression (MLR) methods to generate estimates of limb position and velocity based on a weighted sum of firing rates in an ensemble of simultaneously recorded DRG neurons. The aim of this study was to test whether the use of a neuro-fuzzy (NF) algorithm (the generalized dynamic fuzzy neural networks (GD-FNN)) could improve the performance, robustness and ability to generalize from training to test sets compared to the MLR technique. NF and MLR decoding methods were applied to ensemble DRG recordings obtained during passive and active limb movements in anesthetized and freely moving cats. The GD-FNN model provided more accurate estimates of limb state and generalized better to novel movement patterns. Future efforts will focus on implementing these neural recording and decoding methods in real time to provide closed-loop control of FES using the information extracted from sensory neurons.

  6. Enhancement of Schwann cell myelin formation by K252a in the Trembler-J mouse dorsal root ganglion explant culture.

    PubMed

    Liu, Ning; Varma, Sushama; Shooter, Eric M; Tolwani, Ravi J

    2005-02-01

    The Trembler-J (TrJ) mouse, containing a point mutation in the peripheral myelin protein 22 gene, is characterized by severe hypomyelination and is a representative model of Charcot-Marie-Tooth 1A disease/Dejerine-Sottas Syndrome. Previous studies have shown that protein kinase inhibitor K252a enhances wild-type Schwann cell myelination in culture. We used a dorsal root ganglion (DRG) explant culture system from the heterozygous TrJ/+ mouse to investigate if myelination could be enhanced by K252a. The TrJ/+ DRG explant cultures replicated some important features of the TrJ/+ mouse, showing reduced myelin protein accumulation, thinner myelin sheaths, and shortened myelin internodes. K252a increased myelin protein accumulation and myelin sheath thickness but did not substantially increase myelin internode length. Furthermore, the TrJ/+ DRG explant culture and sciatic nerves continued to respond to K252a during the stage when myelination is complete in the wild type. A general tyrosine kinase inhibitor, genistein, but not inhibitors of serine/threonine protein kinase inhibitors, had a similar effect to K252a. K252a is therefore able to partially overcome hypomyelination by enhancing mutant Schwann cell myelin formation in the TrJ/+ mouse.

  7. A proximal E-box modulates NGF effects on rat PPT-A promoter activity in cultured dorsal root ganglia neurones.

    PubMed

    Gerrard, Lesley; Howard, Mark; Paterson, Trevor; Thippeswamy, Thimmasettappa; Quinn, John P; Haddley, Kate

    2005-10-01

    The rat preprotachykinin A (rtPPTA) promoter fragment spanning -865+92, relative to the major transcriptional start, has previously been demonstrated to be nerve growth factor (NGF) responsive in primary cultures of rat dorsal root ganglion (DRG) neurones [Harrison, P.T., Dalziel, R.G., Ditchfield, N.A., Quinn, J.P., 1999. Neuronal-specific and nerve growth factor-inducible expression directed by the preprotachykinin-A promoter delivered by an adeno-associated virus vector. Neuroscience 94, 997-1003]. In this communication, we demonstrate that an E box element at -60, in part, regulates the activity of this rtPPT-A promoter fragment in DRG neurones in response to NGF. Differential regulation of the promoter is observed in the presence or absence of NGF when the E Box site is present. Under basal conditions binding of proteins to this -60 element may antagonise promoter activity. Hence, in the absence of NGF, mutation of the -60 E box increased reporter gene expression. Further, comparison of levels of reporter gene expression supported by both WT and mutated promoter indicate that in the presence of NGF the -60 E box element also plays a role as an activator domain. This represents a novel mechanism for NGF regulation of rtPPT-A. Similarly, an important role for this signalling pathway was observed in neonate rat DRG neuronal cultures, which require NGF for their survival, namely mutation of the -60 element resulted in higher levels of reporter gene expression.

  8. Dorsal root ganglia neurons and differentiated adipose-derived stem cells: an in vitro co-culture model to study peripheral nerve regeneration.

    PubMed

    de Luca, Alba C; Faroni, Alessandro; Reid, Adam J

    2015-02-26

    Dorsal root ganglia (DRG) neurons, located in the intervertebral foramina of the spinal column, can be used to create an in vitro system facilitating the study of nerve regeneration and myelination. The glial cells of the peripheral nervous system, Schwann cells (SC), are key facilitators of these processes; it is therefore crucial that the interactions of these cellular components are studied together. Direct contact between DRG neurons and glial cells provides additional stimuli sensed by specific membrane receptors, further improving the neuronal response. SC release growth factors and proteins in the culture medium, which enhance neuron survival and stimulate neurite sprouting and extension. However, SC require long proliferation time to be used for tissue engineering applications and the sacrifice of an healthy nerve for their sourcing. Adipose-derived stem cells (ASC) differentiated into SC phenotype are a valid alternative to SC for the set-up of a co-culture model with DRG neurons to study nerve regeneration. The present work presents a detailed and reproducible step-by-step protocol to harvest both DRG neurons and ASC from adult rats; to differentiate ASC towards a SC phenotype; and combines the two cell types in a direct co-culture system to investigate the interplay between neurons and SC in the peripheral nervous system. This tool has great potential in the optimization of tissue-engineered constructs for peripheral nerve repair.

  9. Short-Term Ketamine Treatment Decreases Oxidative Stress Without Influencing TRPM2 and TRPV1 Channel Gating in the Hippocampus and Dorsal Root Ganglion of Rats.

    PubMed

    Demirdaş, Arif; Nazıroğlu, Mustafa; Övey, Ishak Suat

    2017-01-01

    Calcium ions (Ca(2+)) are important second messengers in neurons. Ketamine (KETAM) is an anesthetic and analgesic, with psychotomimetic effects and abuse potential. KETAM modulates the entry of Ca(2+) in neurons through glutamate receptors, but its effect on transient receptor potential melastatin 2 (TRPM2) and transient receptor potential vanilloid 1 (TRPV1) channels has not been clarified. This study investigated the short-term effects of KETAM on oxidative stress and TRPM2 and TRPV1 channel gating in hippocampal and dorsal root ganglion (DRG) neurons of rats. Freshly isolated hippocampal and DRG neurons were incubated for 24 h with KETAM (0.3 mM). The TRPM2 channel antagonist, N-(p-amylcinnamoyl)anthranilic acid (ACA), inhibited cumene hydroperoxide and ADP-ribose-induced TRPM2 currents in the neurons, and capsazepine (CPZ) inhibited capsaicin-induced TRPV1 currents. The TRPM2 and TRPV1 channel current densities and intracellular free calcium ion concentration of the neurons were lower in the neurons exposed to ACA and CPZ compared to the control neurons, respectively. However, the values were not further decreased by the KETAM + CPZ and KETAM + ACA treatments. KETAM decreased lipid peroxidation levels in the neurons but increased glutathione peroxidase activity. In conclusion, short-term KETAM treatment decreased oxidative stress levels but did not seem to influence TRPM2- and TRPV1-mediated Ca(2+) entry.

  10. Activation of the cGMP/Protein Kinase G Pathway by Nitric Oxide Can Decrease TRPV1 Activity in Cultured Rat Dorsal Root Ganglion Neurons

    PubMed Central

    Jin, Yunju; Kim, Jun

    2012-01-01

    Recent studies have demonstrated that nitric oxide (NO) activates transient receptor potential vanilloid subtype 1 (TRPV1) via S-nitrosylation of the channel protein. NO also modulates various cellular functions via activation of the soluble guanylyl cyclase (sGC)/protein kinase G (PKG) pathway and the direct modification of proteins. Thus, in the present study, we investigated whether NO could indirectly modulate the activity of TRPV1 via a cGMP/PKG-dependent pathway in cultured rat dorsal root ganglion (DRG) neurons. NO donors, sodium nitroprusside (SNP) and S-nitro-N-acetylpenicillamine (SNAP), decreased capsaicin-evoked currents (Icap). NO scavengers, hemoglobin and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO), prevented the inhibitory effect of SNP on Icap. Membrane-permeable cGMP analogs, 8-bromoguanosine 3', 5'-cyclic monophosphate (8bromo-cGMP) and 8-(4chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (8-pCPT-cGMP), and the guanylyl cyclase stimulator YC-1 mimicked the effect of SNP on Icap. The PKG inhibitor KT5823 prevented the inhibition of Icap by SNP. These results suggest that NO can downregulate the function of TRPV1 through activation of the cGMP/PKG pathway in peripheral sensory neurons. PMID:22802704

  11. Involvement of lysophosphatidic acid in bone cancer pain by potentiation of TRPV1 via PKCε pathway in dorsal root ganglion neurons.

    PubMed

    Pan, Hai-Li; Zhang, Yu-Qiu; Zhao, Zhi-Qi

    2010-12-01

    It has been demonstrated that lysophosphatidic acid (LPA) released from injury tissue and transient receptor potential vanilloid 1 (TRPV1) receptor are implicated in the induction of chronic pain. In the present study we examined whether an interaction between LPA receptor LPA(1) and TRPV1 in dorsal root ganglion (DRG) neurons contributes to the development of bone cancer pain. Bone cancer was established by injection of mammary gland carcinoma cells into the rat tibia. Following the development of bone cancer pain, the TRPV1 expression and capsaicin-evoked currents were up-regulated in rat DRG neurons at L(4-6) segments. Immunohistochemistry staining revealed a high co-localization of LPA(1) with TRPV1 in DRG neurons. In isolated DRG neurons, whole-cell patch recording showed that capsaicin-induced currents were potentiated by LPA in a dose-dependent manner. The potentiation was blocked by either LPA(1) antagonist, protein kinase C (PKC) inhibitor or PKCε inhibitor, but not by protein kinase A (PKA) inhibitor or Rho inhibitor. In the behavioral tests, both mechanical allodynia and thermal hyperalgesia in bone cancer rats were attenuated by LPA(1) antagonist. LPA potentiates TRPV1 current via a PKCε-dependent pathway in DRG neurons of rats with bone cancer, which may be a novel peripheral mechanism underlying the induction of bone cancer pain.

  12. Fabrication of growth factor- and extracellular matrix-loaded, gelatin-based scaffolds and their biocompatibility with Schwann cells and dorsal root ganglia

    PubMed Central

    Gámez Sazo, Rodolfo E.; Maenaka, Katsumi; Gu, Weiyong; Wood, Patrick M.; Bunge, Mary Bartlett

    2012-01-01

    One of the most exciting new avenues of research to repair the injured spinal cord is to combine cells for implantation with scaffolds that protect the cells and release growth factors to improve their survival and promote host axonal regeneration. To realize this goal, we fabricated biodegradable, photocurable gelatin tubes and membranes for exploratory in vitro studies. Detailed methods are described for their fabrication with a high gelatin concentration. Gelatin membranes fabricated in the same way as tubes and photo-co-immobilized with rhBDNF or rhNT-3, with or without Schwann cells (SCs), showed an initial burst of neurotrophin release within 24h, with release diminishing progressively for 21 days thereafter. SCs attained their typical bipolar conformation on membranes without neurotrophins but adhesion, alignment and proliferation were improved with neurotrophins, particularly rhBDNF. When dorsal root ganglion explants were cultured on membranes containing laminin and fibronectin plus both neurotrophins, neurite outgrowth was lengthier compared to combining one neurotrophin with laminin and fibronectin. Thus, these gelatin membranes allow SC survival and effectively release growth factors and harbor extracellular matrix components to improve cell survival and neurite growth. These scaffolds, based on the combination of cross-linked gelatin technology and incorporation of neurotrophins and extracellular matrix components, are promising candidates for spinal cord repair. PMID:22906605

  13. In vivo effects of L1 coating on inflammation and neuronal health at the electrode/tissue interface in rat spinal cord and dorsal root ganglion

    PubMed Central

    Kolarcik, Christi L.; Bourbeau, Dennis; Azemi, Erdrin; Rost, Erika; Zhang, Ling; Lagenaur, Carl F.; Weber, Douglas J.; Cui, X. Tracy

    2012-01-01

    The spinal cord (SC) and dorsal root ganglion (DRG) are target implantation regions for neural prosthetics, but the tissue-electrode interface in these regions is not well-studied. To improve our understanding of these locations, we characterized the tissue reactions around implanted electrodes. L1, an adhesion molecule shown to maintain neuronal density and reduce gliosis in brain tissue, was then evaluated in SC and DRG implants. Following L1 immobilization onto neural electrodes, the bioactivities of the coatings were verified in vitro using neuron, astrocyte and microglia cultures. Non-modified and L1-coated electrodes were implanted into adult rats for 1 or 4 weeks. Hematoxylin and eosin staining along with cell-type specific antibodies were used to characterize the tissue response. In the SC and DRG, cells aggregated at the electrode-tissue interface. Microglia staining was more intense around the implant site and decreased with distance from the interface. Neurofilament staining in both locations was decreased or absent around the implant when compared to surrounding tissue. With L1, neurofilament staining was significantly increased while neuronal cell death decreased. Our results indicate that L1-modified electrodes may result in an improved chronic neural interface and will be evaluated in recording and stimulation studies. PMID:22750248

  14. Characterization of in vitro transcriptional responses of dorsal root ganglia cultured in the presence and absence of blastema cells from regenerating salamander limbs

    PubMed Central

    Athippozhy, Antony; Lehrberg, Jeffrey; Monaghan, James R.; Gardiner, David M.

    2014-01-01

    Abstract During salamander limb regeneration, nerves provide signals that induce the formation of a mass of proliferative cells called the blastema. To better understand these signals, we developed a blastema−dorsal root ganglia (DRG) co‐culture model system to test the hypothesis that nerves differentially express genes in response to cues provided by the blastema. DRG with proximal and distal nerve trunks were isolated from axolotls (Ambystoma mexicanum), cultured for 5 days, and subjected to microarray analysis. Relative to freshly isolated DRG, 1541 Affymetrix probe sets were identified as differentially expressed and many of the predicted genes are known to function in injury and neurodevelopmental responses observed for mammalian DRG. We then cultured 5‐day DRG explants for an additional 5 days with or without co‐cultured blastema cells. On day 10, we identified 27 genes whose expression in cultured DRG was significantly affected by the presence or absence of blastema cells. Overall, our study established a DRG−blastema in vitro culture system and identified candidate genes for future investigations of axon regrowth, nerve−blastema signaling, and neural regulation of limb regeneration. PMID:25750744

  15. Potentiation of acid-sensing ion channel activity by the activation of 5-HT₂ receptors in rat dorsal root ganglion neurons.

    PubMed

    Qiu, Fang; Qiu, Chun-Yu; Liu, Yu-Qiang; Wu, Dan; Li, Jia-Da; Hu, Wang-Ping

    2012-09-01

    Acid-sensing ion channels (ASICs), as key sensors for extracellular protons, are expressed in nociceptive sensory neurons and contribute to signalling pain caused by tissue acidosis. ASICs are also the subject of various factors. Here, we further provide evidence that the activity of ASICs is potentiated by the activation of 5-HT₂ receptors in rat dorsal root ganglion neurons. A specific 5-HT₂ receptor agonist, α-methyl-5-HT, dose-dependently enhanced proton-gated currents with an EC₅₀ of 0.13 ± 0.07 nM. The α-methyl-5-HT enhancing effect on proton-gated currents was blocked by cyproheptadine, a 5-HT₂ receptor antagonist, and removed by intracellular dialysis of either GDP-β-S or protein kinase C inhibitor GF109203X. Moreover, α-methyl-5-HT altered acid-evoked membrane excitability of rat DRG neurons and caused a significant increase in the amplitude of the depolarization and the number of spikes induced by acid stimuli. Finally, α-methyl-5-HT increased nociceptive responses to injection of acetic acid in rats. These results suggest that α-methyl-5-HT up-regulates the activity of ASICs via 5-HT₂ receptor and protein kinase C dependent signal pathways in rat primary sensory neurons and this potentiation contributed to acid- mediated pain in tissue injury and inflammation.

  16. Mechanical compression insults induce nanoscale changes of membrane-skeleton arrangement which could cause apoptosis and necrosis in dorsal root ganglion neurons.

    PubMed

    Quan, Xin; Guo, Kai; Wang, Yuqing; Huang, Liangliang; Chen, Beiyu; Ye, Zhengxu; Luo, Zhuojing

    2014-01-01

    In a primary spinal cord injury, the amount of mechanical compression insult that the neurons experience is one of the most critical factors in determining the extent of the injury. The ultrastructural changes that neurons undergo when subjected to mechanical compression are largely unknown. In the present study, using a compression-driven instrument that can simulate mechanical compression insult, we applied mechanical compression stimulation at 0.3, 0.5, and 0.7 MPa to dorsal root ganglion (DRG) neurons for 10 min. Combined with atomic force microscopy, we investigated nanoscale changes in the membrane-skeleton, cytoskeleton alterations, and apoptosis induced by mechanical compression injury. The results indicated that mechanical compression injury leads to rearrangement of the membrane-skeleton compared with the control group. In addition, mechanical compression stimulation induced apoptosis and necrosis and also changed the distribution of the cytoskeleton in DRG neurons. Thus, the membrane-skeleton may play an important role in the response to mechanical insults in DRG neurons. Moreover, sudden insults caused by high mechanical compression, which is most likely conducted by the membrane-skeleton, may induce necrosis, apoptosis, and cytoskeletal alterations.

  17. Intrathecal delivery of frataxin mRNA encapsulated in lipid nanoparticles to dorsal root ganglia as a potential therapeutic for Friedreich’s ataxia

    PubMed Central

    Nabhan, Joseph F.; Wood, Kristy M.; Rao, Varada P.; Morin, Jeffrey; Bhamidipaty, Surya; LaBranche, Timothy P.; Gooch, Renea L.; Bozal, Fazli; Bulawa, Christine E.; Guild, Braydon C.

    2016-01-01

    In Friedreich’s ataxia (FRDA) patients, diminished frataxin (FXN) in sensory neurons is thought to yield the predominant pathology associated with disease. In this study, we demonstrate successful usage of RNA transcript therapy (RTT) as an exogenous human FXN supplementation strategy in vitro and in vivo, specifically to dorsal root ganglia (DRG). Initially, 293 T cells were transfected with codon optimized human FXN mRNA, which was translated to yield FXN protein. Importantly, FXN was rapidly processed into the mature functional form of FXN (mFXN). Next, FXN mRNA, in the form of lipid nanoparticles (LNPs), was administered intravenously in adult mice. Examination of liver homogenates demonstrated efficient FXN LNP uptake in hepatocytes and revealed that the mitochondrial maturation machinery had efficiently processed all FXN protein to mFXN in ~24 h in vivo. Remarkably, greater than 50% mFXN protein derived from LNPs was detected seven days after intravenous administration of FXN LNPs, suggesting that the half-life of mFXN in vivo exceeds one week. Moreover, when FXN LNPs were delivered by intrathecal administration, we detected recombinant human FXN protein in DRG. These observations provide the first demonstration that RTT can be used for the delivery of therapeutic mRNA to DRG. PMID:26883577

  18. Calcium signals activated by ghrelin and D-Lys(3)-GHRP-6 ghrelin antagonist in developing dorsal root ganglion glial cells.

    PubMed

    Erriquez, Jessica; Bernascone, Silvia; Ciarletta, Monica; Filigheddu, Nicoletta; Graziani, Andrea; Distasi, Carla

    2009-09-01

    Ghrelin is a hormone regulating energy homeostasis via interaction with its receptor, GHSR-1a. Ghrelin activities in dorsal root ganglia (DRG) cells are unknown. Herein we show that ghrelin induces a change of cytosolic calcium concentration in both glia and neurons of embryonic chick DRG. Both RT-PCR and binding studies performed with fluorescent ghrelin in the presence of either unlabeled ghrelin or GHSR-1a antagonist D-Lys(3)-GHRP-6, indicate that DRG cells express GHSR-1a. In glial cells the response is characterized by a rapid transient rise in [Ca(2+)](i) followed by a long lasting rise. The calcium elevation is dependent on calcium release from thapsigargin-sensitive intracellular stores and on activation of two distinct Ca(2+) entry pathways, a receptor activated calcium entry and a store operated calcium entry. Surprisingly, D-Lys(3)-GHRP-6 exerts several activities in the absence of exogenous ghrelin: (i) it activates calcium release from thapsigargin-sensitive intracellular stores and calcium entry via voltage-operated channels in non-neuronal cells; (ii) it inhibits calcium oscillations in non-neuronal cells exhibiting spontaneous Ca(2+) activity and iii) it promotes apoptosis of DRG cells, both neurons and glia. In summary, we provide the first evidence for ghrelin activity in DRG, and we also demonstrate that the widely used D-Lys(3)-GHRP-6 ghrelin antagonist features ghrelin independent activities.

  19. Atorvastatin prevents neuroinflammation in chronic constriction injury rats through nuclear NFκB downregulation in the dorsal root ganglion and spinal cord.

    PubMed

    Chu, Li-Wen; Chen, Jun-Yih; Wu, Pao-Chu; Wu, Bin-Nan

    2015-06-17

    Atorvastatin, traditionally used to treat hyperlipidemia, belongs to a class of 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors. This study investigated the antineuroinflammatory and antihyperalgesic effects of atorvastatin in dorsal root ganglia (DRG) and spinal cord for chronic constriction injury (CCI) neuropathic pain in rats. Fifty-four Sprague-Dawley rats were divided into three groups including sham, CCI, and CCI+atorvastatin. Rats were orally administered atorvastatin (10 mg/kg/day) once daily for 2 weeks after surgery and sacrificed at days 3, 7, and 14. All animals were assessed for mechanical allodynia and thermal hyperalgesia in both hindpaws. Western blotting, immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) were used to detect inflammatory proteins and proinflammatory cytokines at day 7 after surgery. Pain behaviors were significantly reduced in the CCI+atorvastatin group compared to the CCI group. Atorvastatin attenuated CCI-induced inflammatory mediators (pAkt/Akt, COX-2, iNOS, EP1, and EP4) and reduced proinflammatory cytokines TNF-α and IL-1β levels in DRG and spinal cord. Atorvastatin also inhibited nuclear pNFκB activation. Double immunofluorescent staining further demonstrated that pNFκB proteins were decreased by atorvastatin in DRG satellite cells and spinal microglia. Atorvastatin may primarily inhibit the nuclear translocation of pNFκB to prevent CCI-induced peripheral neuropathic pain. Atorvastatin exhibits antineuroinflammatory and antinociceptive properties in the central and peripheral nerve systems.

  20. [A computer simulation research for the effects of dragon's blood and its component loureirin B on sodium channel in dorsal root ganglion cells].

    PubMed

    Chen, Su; Liu, Xiangming

    2006-12-01

    Using patch clamp technique the effects of dragon's blood and its component loureirin B on tetrodotoxin-sensitive sodium channel currents in dorsal root ganglion cells were observed. The experimental data were simulated with Hodgkin-Huxley model and the corresponding parameters were estimated. In addition, computer-simulated neuron action potentials in the absence and presence of drugs were produced using Hodgkin-Huxley model. The results show that the conductance of tetrodotoxin-sensitive sodium channel was fitted with m3h model well, the half-activated potentials of the sodium channel in the presence of drugs were shifted to the depolarizing direction and the threshold intensity of the cells in the presence of drugs was increased. These results demonstrate that dragon's blood and loureirin B did not resemble the tetrodotoxin which inhibited tetrodotoxin-sensitive sodium channel currents completely. Perhaps the analgesic effects of dragon's blood were partly caused by loureirin B affecting the activation, blocking the action potential generation and interfering with the transmission of painful signals into the central nervous system.

  1. Pulsed Radiofrequency of Dorsal Root Ganglia for the Treatment of Complex Regional Pain Syndrome in an Adolescent with Poliomyelitis Sequel: A Case Report.

    PubMed

    Apiliogullari, Seza; Aydin, Bahattin Kerem; Onal, Ozkan; Kirac, Yunus; Celik, Jale Bengi

    2015-07-01

    Complex regional pain syndrome (CRPS) is a painful and disabling syndrome in which the patient presents with neuropathic pain, edema, or vasomotor or pseudomotor abnormalities that are often refractory to treatment. Polio paralysis is caused by the damage or destruction of motor neurons in the spine, which lead to corresponding muscle paralysis. This report is a case report on the application of a pulsed radiofrequency (PRF) current to dorsal root ganglia (DRG) for the treatment of CRPS type 1 in an adolescent patient. Single case report. Selcuk University Hospital. A 16-year-old girl who suffered from CRPS type 1 secondary to surgeries for the sequelae of poliomyelitis. PRF current application to the lumbar 4 and lumbar 5 DRG. Pain reduction. The patient had complete resolution of her symptoms, which was maintained at a 6-month follow-up. This case illustrates that PRF applied to lumbar 4 and lumbar 5 DRG may play a significant role in CRPS type 1 management after the surgical treatment of poliomyelitis sequelae in adolescent patients. Further randomized, controlled studies are needed to support this argument. Wiley Periodicals, Inc.

  2. Mitofusin 2 expression dominates over mitofusin 1 exclusively in mouse dorsal root ganglia - a possible explanation for peripheral nervous system involvement in Charcot-Marie-Tooth 2A.

    PubMed

    Kawalec, Maria; Zabłocka, Barbara; Kabzińska, Dagmara; Neska, Jacek; Beręsewicz, Małgorzata

    2014-01-01

    Mitofusin 2 (Mfn2), a protein of the mitochondrial outer membrane, is essential for mitochondrial fusion and contributes to the maintenance and operation of the mitochondrial network. Mutations in the mitofusin 2 gene cause axonal Charcot-Marie-Tooth type 2A (CMT2A), an inherited disease affecting peripheral nerve axons. The precise mechanism by which mutations in MFN2 selectively cause the degeneration of long peripheral axons is not known. There is a hypothesis suggesting the involvement of reduced expression of a homologous protein, mitofusin 1 (Mfn1), in the peripheral nervous system, and less effective compensation of defective mitofusin 2 by mitofusin 1. We therefore aimed to perform an analysis of the mitofusin 1 and mitofusin 2 mRNA and protein expression profiles in different mouse tissues, with special attention paid to dorsal root ganglia (DRGs), as parts of the peripheral nervous system. Quantitative measurement relating to mRNA revealed that expression of the Mfn2 gene dominates over Mfn1 mainly in mouse DRG, as opposed to other nervous system samples and other tissues studied. This result was further supported by Western blot evaluation. Both these sets of data confirm the hypothesis that the cellular consequences of mutations in the mitofusin 2 gene can mostly be manifested in the peripheral nervous system.

  3. The Venom of the Spider Selenocosmia Jiafu Contains Various Neurotoxins Acting on Voltage-Gated Ion Channels in Rat Dorsal Root Ganglion Neurons

    PubMed Central

    Hu, Zhaotun; Zhou, Xi; Chen, Jia; Tang, Cheng; Xiao, Zhen; Ying, Dazhong; Liu, Zhonghua; Liang, Songping

    2014-01-01

    Selenocosmia jiafu is a medium-sized theraphosid spider and an attractive source of venom, because it can be bred in captivity and it produces large amounts of venom. We performed reversed-phase high-performance liquid chromatography (RP-HPLC) and matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analyses and showed that S. jiafu venom contains hundreds of peptides with a predominant mass of 3000–4500 Da. Patch clamp analyses indicated that the venom could inhibit voltage-gated Na+, K+ and Ca2+ channels in rat dorsal root ganglion (DRG) neurons. The venom exhibited inhibitory effects on tetrodotoxin-resistant (TTX-R) Na+ currents and T-type Ca2+ currents, suggesting the presence of antagonists to both channel types and providing a valuable tool for the investigation of these channels and for drug development. Intra-abdominal injection of the venom had severe toxic effects on cockroaches and caused death at higher concentrations. The LD50 was 84.24 μg/g of body weight in the cockroach. However, no visible symptoms or behavioral changes were detected after intraperitoneal injection of the venom into mice even at doses up to 10 mg/kg body weight. Our results provide a basis for further case-by-case investigations of peptide toxins from this venom. PMID:24603666

  4. Inhibition of cystathionine β-synthetase suppresses sodium channel activities of dorsal root ganglion neurons of rats with lumbar disc herniation

    PubMed Central

    Yan, Jun; Hu, Shufen; Zou, Kang; Xu, Min; Wang, Qianliang; Miao, Xiuhua; Yu, Shan Ping; Xu, Guang-Yin

    2016-01-01

    The pathogenesis of pain in lumbar disc herniation (LDH) remains poorly understood. We have recently demonstrated that voltage-gated sodium channels (VGSCs) in dorsal root ganglion (DRG) neurons were sensitized in a rat model of LDH. However, the detailed molecular mechanism for sensitization of VGSCs remains largely unknown. This study was designed to examine roles of the endogenous hydrogen sulfide synthesizing enzyme cystathionine β-synthetase (CBS) in sensitization of VGSCs in a previously validated rat model of LDH. Here we showed that inhibition of CBS activity by O-(Carboxymethyl) hydroxylamine hemihydrochloride (AOAA) significantly attenuated pain hypersensitivity in LDH rats. Administration of AOAA also reduced neuronal hyperexcitability, suppressed the sodium current density, and right-shifted the V1/2 of the inactivation curve, of hindpaw innervating DRG neurons, which is retrogradely labeled by DiI. In vitro incubation of AOAA did not alter the excitability of acutely isolated DRG neurons. Furthermore, CBS was colocalized with NaV1.7 and NaV1.8 in hindpaw-innervating DRG neurons. Treatment of AOAA markedly suppressed expression of NaV1.7 and NaV1.8 in DRGs of LDH rats. These data suggest that targeting the CBS-H2S signaling at the DRG level might represent a novel therapeutic strategy for chronic pain relief in patients with LDH. PMID:27905525

  5. Creating a Strain Relief Loop during S1 Transforaminal Lead Placement for Dorsal Root Ganglion Stimulation for Foot Pain: A Technical Note.

    PubMed

    van Velsen, Valery; van Helmond, Noud; Chapman, Kenneth B

    2017-09-01

    Chronic neuropathic pain is often refractory to conventional medical treatments and leads to significant disability and socio-economic burden. Dorsal root ganglion (DRG) stimulation has recently emerged as a treatment for persistent neuropathic pain, but creating a strain relief loop on the S1 level has thus far been a challenging technical component of DRG lead placement. We describe a refined technique for strain relief loop formation on the S1 level using a transforaminal approach that we employed in a 45-year old patient with intractable foot pain. We successfully placed a strain relief loop in the sacral space in a predictable and easily reproducible manner using a transforaminal anchorless approach. The patient experienced a decrease in visual analogue pain score (85%), and improvement in function during the trial period, and proceeded with permanent implantation. The described sacral transforaminal strain relief loop formation technique appears to be a more reliable and predictable technique of DRG lead placement in the sacrum than those previously documented. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.