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1.
Nat Neurosci ; 22(11): 1913-1924, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31591560

RESUMEN

Axonal injury results in regenerative success or failure, depending on whether the axon lies in the peripheral or the CNS, respectively. The present study addresses whether epigenetic signatures in dorsal root ganglia discriminate between regenerative and non-regenerative axonal injury. Chromatin immunoprecipitation for the histone 3 (H3) post-translational modifications H3K9ac, H3K27ac and H3K27me3; an assay for transposase-accessible chromatin; and RNA sequencing were performed in dorsal root ganglia after sciatic nerve or dorsal column axotomy. Distinct histone acetylation and chromatin accessibility signatures correlated with gene expression after peripheral, but not central, axonal injury. DNA-footprinting analyses revealed new transcriptional regulators associated with regenerative ability. Machine-learning algorithms inferred the direction of most of the gene expression changes. Neuronal conditional deletion of the chromatin remodeler CCCTC-binding factor impaired nerve regeneration, implicating chromatin organization in the regenerative competence. Altogether, the present study offers the first epigenomic map providing insight into the transcriptional response to injury and the differential regenerative ability of sensory neurons.


Asunto(s)
Axones/fisiología , Epigenómica , Ganglios Espinales/fisiología , Regeneración Nerviosa/fisiología , Células Receptoras Sensoriales/fisiología , Acetilación , Algoritmos , Animales , Factor de Unión a CCCTC/genética , Cromatina/metabolismo , Femenino , Ganglios Espinales/lesiones , Expresión Génica , Histonas/metabolismo , Aprendizaje Automático , Masculino , Ratones , Ratones Transgénicos , Nervio Ciático/lesiones , Análisis de Secuencia de ARN
2.
Nat Commun ; 10(1): 3087, 2019 07 12.
Artículo en Inglés | MEDLINE | ID: mdl-31300648

RESUMEN

The dorsal root ganglia (DRG) contain the somas of first-order sensory neurons critical for somatosensation. Due to technical difficulties, DRG neuronal activity in awake behaving animals remains unknown. Here, we develop a method for imaging DRG at cellular and subcellular resolution over weeks in awake mice. The method involves the installation of an intervertebral fusion mount to reduce spinal movement, and the implantation of a vertebral glass window without interfering animals' motor and sensory functions. In vivo two-photon calcium imaging shows that DRG neuronal activity is higher in awake than anesthetized animals. Immediately after plantar formalin injection, DRG neuronal activity increases substantially and this activity upsurge correlates with animals' phasic pain behavior. Repeated imaging of DRG over 5 weeks after formalin injection reveals persistent neuronal hyperactivity associated with ongoing pain. The method described here provides an important means for in vivo studies of DRG functions in sensory perception and disorders.


Asunto(s)
Ganglios Espinales/diagnóstico por imagen , Microscopía Intravital/métodos , Percepción del Dolor/fisiología , Células Receptoras Sensoriales/fisiología , Animales , Técnicas de Observación Conductual/instrumentación , Técnicas de Observación Conductual/métodos , Conducta Animal/fisiología , Calcio/química , Femenino , Formaldehído/administración & dosificación , Formaldehído/toxicidad , Ganglios Espinales/citología , Ganglios Espinales/fisiología , Proteínas Fluorescentes Verdes/química , Proteínas Fluorescentes Verdes/genética , Microscopía Intravital/instrumentación , Masculino , Ratones , Ratones Transgénicos , Modelos Animales , Imagen Óptica/instrumentación , Imagen Óptica/métodos , Dolor/inducido químicamente , Dolor/fisiopatología , Fotones , Vigilia
3.
EMBO J ; 38(13): e101032, 2019 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-31268609

RESUMEN

The molecular mechanisms discriminating between regenerative failure and success remain elusive. While a regeneration-competent peripheral nerve injury mounts a regenerative gene expression response in bipolar dorsal root ganglia (DRG) sensory neurons, a regeneration-incompetent central spinal cord injury does not. This dichotomic response offers a unique opportunity to investigate the fundamental biological mechanisms underpinning regenerative ability. Following a pharmacological screen with small-molecule inhibitors targeting key epigenetic enzymes in DRG neurons, we identified HDAC3 signalling as a novel candidate brake to axonal regenerative growth. In vivo, we determined that only a regenerative peripheral but not a central spinal injury induces an increase in calcium, which activates protein phosphatase 4 that in turn dephosphorylates HDAC3, thus impairing its activity and enhancing histone acetylation. Bioinformatics analysis of ex vivo H3K9ac ChIPseq and RNAseq from DRG followed by promoter acetylation and protein expression studies implicated HDAC3 in the regulation of multiple regenerative pathways. Finally, genetic or pharmacological HDAC3 inhibition overcame regenerative failure of sensory axons following spinal cord injury. Together, these data indicate that PP4-dependent HDAC3 dephosphorylation discriminates between axonal regeneration and regenerative failure.


Asunto(s)
Ganglios Espinales/fisiología , Histona Desacetilasas/metabolismo , Traumatismos de los Nervios Periféricos/metabolismo , Fosfoproteínas Fosfatasas/metabolismo , Bibliotecas de Moléculas Pequeñas/farmacología , Animales , Axones , Células Cultivadas , Modelos Animales de Enfermedad , Epigénesis Genética/efectos de los fármacos , Femenino , Masculino , Ratones , Regeneración Nerviosa , Fosforilación/efectos de los fármacos , Transducción de Señal
4.
Int J Mol Sci ; 20(11)2019 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-31141907

RESUMEN

Melatonin is a neurohormone produced and secreted at night by pineal gland. Many effects of melatonin have already been described, for example: Activation of potassium channels in the suprachiasmatic nucleus and inhibition of excitability of a sub-population of neurons of the dorsal root ganglia (DRG). The DRG is described as a structure with several neuronal populations. One classification, based on the repolarizing phase of the action potential (AP), divides DRG neurons into two types: Without (N0) and with (Ninf) inflection on the repolarization phase of the action potential. We have previously demonstrated that melatonin inhibits excitability in N0 neurons, and in the present work, we aimed to investigate the melatonin effects on the other neurons (Ninf) of the DRG neuronal population. This investigation was done using sharp microelectrode technique in the current clamp mode. Melatonin (0.01-1000.0 nM) showed inhibitory activity on neuronal excitability, which can be observed by the blockade of the AP and by the increase in rheobase. However, we observed that, while some neurons were sensitive to melatonin effect on excitability (excitability melatonin sensitive-EMS), other neurons were not sensitive to melatonin effect on excitability (excitability melatonin not sensitive-EMNS). Concerning the passive electrophysiological properties of the neurons, melatonin caused a hyperpolarization of the resting membrane potential in both cell types. Regarding the input resistance (Rin), melatonin did not change this parameter in the EMS cells, but increased its values in the EMNS cells. Melatonin also altered several AP parameters in EMS cells, the most conspicuously changed was the (dV/dt)max of AP depolarization, which is in coherence with melatonin effects on excitability. Otherwise, in EMNS cells, melatonin (0.1-1000.0 nM) induced no alteration of (dV/dt)max of AP depolarization. Thus, taking these data together, and the data of previous publication on melatonin effect on N0 neurons shows that this substance has a greater pharmacological potency on Ninf neurons. We suggest that melatonin has important physiological function related to Ninf neurons and this is likely to bear a potential relevant therapeutic use, since Ninf neurons are related to nociception.


Asunto(s)
Potenciales de Acción , Depresores del Sistema Nervioso Central/farmacología , Ganglios Espinales/efectos de los fármacos , Melatonina/farmacología , Neuronas/efectos de los fármacos , Animales , Células Cultivadas , Ganglios Espinales/citología , Ganglios Espinales/fisiología , Masculino , Neuronas/fisiología , Ratas , Ratas Wistar
5.
Res Vet Sci ; 124: 417-425, 2019 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-31078789

RESUMEN

This study reports on the influence of experimentally-induced uterine inflammation on chemical phenotypes, number and distribution of neurons in the dorsal root ganglia (DRGs) innervating the uterus in sexually mature gilts. On day 17 of the first studied estrous cycle, the uterine horns were injected with retrograde tracer Fast Blue (FB). After 28 days (on an expected day 3 of third studied estrous cycle), 50 ml of either saline (group SAL) or Escherichia coli (E. coli) suspension (109 colony-forming units/ml, group E. coli) were injected into each uterine horn. In the control pigs (group CON), only laparotomy was performed. Eight days later DRGs and uteri were collected. All infected gilts developed severe form of acute endometritis. By use of double immunofluorescence labelling the numbers of uterine perikarya expressing substance P (SP), calcitonin gene-related peptide (CGRP), neurokinin A (NKA), galanin (GAL) and pituitary adenylate cyclase-activating polypeptide (PACAP) were analyzed. Injection of E. coli decreased the total number of the FB positive perykaria in the Th10-S4 DRGs. We revealed an increase in the populations of uterine perikarya coded SP+/CGRP-, SP+/NKA-, SP-/NKA+, SP+/GAL+, SP+/GAL-, SP-/GAL+, SP+/PACAP+ and SP-/PACAP+. Our results suggest that uterine inflammation affects both the spatial and neurochemical organization pattern of uterine sensory innervation. Additionally, the inflammation may affect the transmission of sensory information from uterus to spinal cord.


Asunto(s)
Endometritis/veterinaria , Ganglios Espinales/fisiología , Sus scrofa/fisiología , Enfermedades de los Porcinos/fisiopatología , Útero/inervación , Animales , Endometritis/fisiopatología , Escherichia coli , Infecciones por Escherichia coli/fisiopatología , Infecciones por Escherichia coli/veterinaria , Femenino , Ganglios Espinales/fisiopatología , Distribución Aleatoria , Porcinos/fisiología , Útero/fisiopatología
6.
Toxins (Basel) ; 11(4)2019 04 18.
Artículo en Inglés | MEDLINE | ID: mdl-31003411

RESUMEN

Picrasma quassioides (D. Don) Benn, a medical plant, is used in clinic to treat inflammation, pain, sore throat, and eczema. The alkaloids are the main active components in P. quassioides. In this study, we examined the analgesic effect of dehydrocrenatidine (DHCT), a ß-carboline alkaloid abundantly found in P. quassioides in a neuropathic pain rat model of a sciatic nerve chronic constriction injury. DHCT dose-dependently attenuated the mechanic allodynia. In acutely isolated dorsal root ganglion, DHCT completely suppressed the action potential firing. Further electrophysiological characterization demonstrated that DHCT suppressed both tetrodotoxin-resistant (TTX-R) and sensitive (TTX-S) voltage-gated sodium channel (VGSC) currents with IC50 values of 12.36 µM and 4.87 µM, respectively. DHCT shifted half-maximal voltage (V1/2) of inactivation to hyperpolarizing direction by ~16.7 mV in TTX-S VGSCs. In TTX-R VGSCs, DHCT shifted V1/2 of inactivation voltage to hyperpolarizing direction and V1/2 of activation voltage to more depolarizing potential by ~23.9 mV and ~12.2 mV, respectively. DHCT preferred to interact with an inactivated state of VGSCs and prolonged the repriming time in both TTX-S and TTX-R VGSCs, transiting the channels into a slow inactivated state from a fast inactivated state. Considered together, these data demonstrated that the analgesic effect of DHCT was likely though the inhibition of neuronal excitability.


Asunto(s)
Carbolinas/uso terapéutico , Hiperalgesia/tratamiento farmacológico , Neuralgia/tratamiento farmacológico , Bloqueadores de los Canales de Sodio/uso terapéutico , Analgésicos/farmacología , Analgésicos/uso terapéutico , Animales , Carbolinas/farmacología , Modelos Animales de Enfermedad , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/fisiología , Hiperalgesia/fisiopatología , Masculino , Neuralgia/fisiopatología , Neuronas/efectos de los fármacos , Neuronas/fisiología , Ratas Sprague-Dawley , Nervio Ciático/lesiones , Bloqueadores de los Canales de Sodio/farmacología , Canales de Sodio Activados por Voltaje/fisiología
7.
Mol Pharmacol ; 95(6): 652-660, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30979812

RESUMEN

Cloxyquin has been reported as a specific activator of TRESK [TWIK-related spinal cord K+ channel (also known as K2P18.1)] background potassium channel. In this study, we have synthetized chemically modified analogs of cloxyquin and tested their effects on TRESK and other K2P channels. The currents of murine K2P channels, expressed heterologously in Xenopus oocytes, were measured by two-electrode voltage clamp, whereas the native background K+ conductance of mouse dorsal root ganglion (DRG) neurons was examined by the whole-cell patch-clamp method. Some of the analogs retained the activator character of the parent compound, but, more interestingly, other derivatives inhibited mouse TRESK current. The inhibitor analogs (A2764 and A2793) exerted state-dependent effects. The degree of inhibition by 100 µM A2764 (77.8% ± 3.5%, n = 6) was larger in the activated state of TRESK (i.e., after calcineurin-dependent stimulation) than in the resting state of the channel (42.8% ± 11.5% inhibition, n = 7). The selectivity of the inhibitor compounds was tested on several K2P channels. A2793 inhibited TWIK-related acid-sensitive K+ channel (TASK)-1 (100 µM, 53.4% ± 13, 5%, n = 5), while A2764 was more selective for TRESK, it only moderately influenced TREK-1 and TWIK-related alkaline pH-activated K+ channel. The effect of A2764 was also examined on the background K+ currents of DRG neurons. A subpopulation of DRG neurons, prepared from wild-type animals, expressed background K+ currents sensitive to A2764, whereas the inhibitor did not affect the currents in the DRG neurons of TRESK-deficient mice. Accordingly, A2764 may prove to be useful for the identification of TRESK current in native cells, and for the investigation of the role of the channel in nociception and migraine. SIGNIFICANCE STATEMENT: TRESK background potassium channel is a potential pharmacological target in migraine and neuropathic pain. In this study, we have identified a selective inhibitor of TRESK, A2764. This compound can inhibit TRESK in native cells, leading to cell depolarization and increased excitability. This new inhibitor may be of use to probe the role of TRESK channel in migraine and nociception.


Asunto(s)
Cloroquinolinoles/síntesis química , Ganglios Espinales/fisiología , Canales de Potasio/metabolismo , Animales , Calcineurina/farmacología , Cloroquinolinoles/química , Cloroquinolinoles/farmacología , Femenino , Ganglios Espinales/efectos de los fármacos , Ratones , Estructura Molecular , Técnicas de Placa-Clamp , Xenopus laevis
8.
Proc Natl Acad Sci U S A ; 116(9): 3811-3816, 2019 02 26.
Artículo en Inglés | MEDLINE | ID: mdl-30755524

RESUMEN

The ability to detect environmental cold serves as an important survival tool. The sodium channels NaV1.8 and NaV1.9, as well as the TRP channel Trpm8, have been shown to contribute to cold sensation in mice. Surprisingly, transcriptional profiling shows that NaV1.8/NaV1.9 and Trpm8 are expressed in nonoverlapping neuronal populations. Here we have used in vivo GCaMP3 imaging to identify cold-sensing populations of sensory neurons in live mice. We find that ∼80% of neurons responsive to cold down to 1 °C do not express NaV1.8, and that the genetic deletion of NaV1.8 does not affect the relative number, distribution, or maximal response of cold-sensitive neurons. Furthermore, the deletion of NaV1.8 had no observable effect on transient cold-induced (≥5 °C) behaviors in mice, as measured by the cold-plantar, cold-plate (5 and 10 °C), or acetone tests. In contrast, nocifensive-like behavior to extreme cold-plate stimulation (-5 °C) was completely absent in mice lacking NaV1.8. Fluorescence-activated cell sorting (FACS) and subsequent microarray analysis of sensory neurons activated at 4 °C identified an enriched repertoire of ion channels, which include the Trp channel Trpm8 and potassium channel Kcnk9, that are potentially required for cold sensing above freezing temperatures in mouse DRG neurons. These data demonstrate the complexity of cold-sensing mechanisms in mouse sensory neurons, revealing a principal role for NaV1.8-negative neurons in sensing both innocuous and acute noxious cooling down to 1 °C, while NaV1.8-positive neurons are likely responsible for the transduction of prolonged extreme cold temperatures, where tissue damage causes pan-nociceptor activation.


Asunto(s)
Canal de Sodio Activado por Voltaje NAV1.8/genética , Canales de Potasio/genética , Células Receptoras Sensoriales/fisiología , Canales Catiónicos TRPM/genética , Animales , Frío , Ganglios Espinales/diagnóstico por imagen , Ganglios Espinales/metabolismo , Ganglios Espinales/fisiología , Ratones , Nociceptores/metabolismo , Nociceptores/fisiología , Células Receptoras Sensoriales/metabolismo , Sensación Térmica/genética
9.
PLoS One ; 14(2): e0211731, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30716106

RESUMEN

Three aligned, electrospun fiber scaffolds with unique surface features were created from poly-L-lactic acid (PLLA). Fibers without surface nanotopography (smooth fibers), fibers with surface divots (shallow pits), and fibers with surface pits (deeper pits) were fabricated, and fiber alignment, diameter, and density were characterized using scanning electron microscopy (SEM). Whole dorsal root ganglia (DRG) were isolated from rats and placed onto uncoated fibers or fibers coated with laminin. On uncoated fibers, neurite outgrowth was restricted by fibers displaying divoted or pitted nanotopography when compared to neurite outgrowth on smooth fibers. However, neurites extending from whole DRG cultured on laminin-coated fibers were not restricted by divoted or pitted surface nanotopography. Thus, neurites extending on laminin-coated fibers were able to extend long neurites even in the presence of surface divots or pits. To further explore this result, individual neurons isolated from dissociated DRG were seeded onto laminin-coated smooth, pitted, or divoted fibers. Interestingly, neurons on pitted or divoted fibers exhibited a 1.5-fold increase in total neurite length, and a 2.3 or 2.7-fold increase in neurite branching compared to neurons on smooth fibers, respectively. Based on these findings, we conclude that fiber roughness in the form of pits or divots can promote extension and branching of long neurites along aligned electrospun fibers in the presence of an extracellular matrix protein coating. Thus, aligned, electrospun fibers can be crafted to not only direct the extension of axons but to induce unique branching morphologies.


Asunto(s)
Neuritas/fisiología , Proyección Neuronal/fisiología , Neuronas/fisiología , Animales , Proteínas de la Matriz Extracelular/metabolismo , Ganglios Espinales/metabolismo , Ganglios Espinales/fisiología , Microscopía Electrónica de Rastreo/métodos , Nanotecnología/métodos , Regeneración Nerviosa/fisiología , Neuritas/metabolismo , Neuronas/metabolismo , Poliésteres/química , Ratas , Ratas Sprague-Dawley , Ingeniería de Tejidos/métodos , Andamios del Tejido
10.
Reg Anesth Pain Med ; 44(1): 100-106, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30640660

RESUMEN

BACKGROUND AND OBJECTIVES: Dorsal root ganglion stimulation is an emerging therapy in the treatment of chronic pain. Compared with traditional spinal cord stimulation, it allows a discretely targeted stimulation profile and may act via differing mechanisms of action. Despite these advantages, little is known about the complications associated with this new modality. METHODS: We queried the MAUDE (Manufacturer and User Facility Device Experience) database for all entries named 'Dorsal root ganglion stimulator for pain relief' reported between May 1, 2016 and December 31, 2017. We verified these data through the Office of the Freedom of Information Act at the US Food and Drug Administration. We then eliminated duplicate entries and categorized each complication based on the event description. A secondary analysis was performed to characterize the serious adverse events and the severity of new neurologic symptoms and infections. RESULTS: We identified 979 unique episodes following our process of deduplication. Almost half (47%) of entries were categorized as device-related complications, a quarter (28%) as procedural complications, with the remainder as patient complaints (12%), serious adverse events (2.4%), and 'other' complications (4.6%). The majority of complications were managed surgically with revision (n = 488; 49.8%) rather than explant (n = 161; 16.4%) events, respectively. CONCLUSIONS: The 'Dorsal root ganglion stimulator for pain relief' device has been publicized as a breakthrough in neuromodulation technologies. As with any new technology, we must proceed with caution and re-evaluate effectiveness as information becomes available. The MAUDE database has provided safety data unique for this device that will aid in informed consent and further refinement of this innovative therapy.


Asunto(s)
Bases de Datos Factuales , Ganglios Espinales , Manejo del Dolor/métodos , Estimulación de la Médula Espinal/métodos , United States Food and Drug Administration , Bases de Datos Factuales/tendencias , Migración de Cuerpo Extraño/diagnóstico , Migración de Cuerpo Extraño/etiología , Ganglios Espinales/fisiología , Humanos , Dolor/diagnóstico , Dolor/etiología , Manejo del Dolor/efectos adversos , Estudios Retrospectivos , Estimulación de la Médula Espinal/efectos adversos , Estados Unidos/epidemiología , United States Food and Drug Administration/tendencias
11.
Int J Mol Sci ; 20(1)2019 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-30609840

RESUMEN

We have tested the hypothesis that neuropathic pain acting as a stressor drives functional plasticity in the sympathoadrenal system. The relation between neuropathic pain and adrenal medulla function was studied with behavioral, immunohistochemical and electrophysiological techniques in rats subjected to chronic constriction injury of the sciatic nerve. In slices of the adrenal gland from neuropathic animals, we have evidenced increased cholinergic innervation and spontaneous synaptic activity at the splanchnic nerve⁻chromaffin cell junction. Likewise, adrenomedullary chromaffin cells displayed enlarged acetylcholine-evoked currents with greater sensitivity to α-conotoxin RgIA, a selective blocker of α9 subunit-containing nicotinic acetylcholine receptors, as well as increased exocytosis triggered by voltage-activated Ca2+ entry. Altogether, these adaptations are expected to facilitate catecholamine output into the bloodstream. Last, but most intriguing, functional and immunohistochemical data indicate that P2X3 and P2X7 purinergic receptors and transient receptor potential vanilloid-1 (TRPV1) channels are overexpressed in chromaffin cells from neuropathic animals. These latter observations are reminiscent of molecular changes characteristic of peripheral sensitization of nociceptors following the lesion of a peripheral nerve, and suggest that similar phenomena can occur in other tissues, potentially contributing to behavioral manifestations of neuropathic pain.


Asunto(s)
Neuralgia/patología , Receptores Purinérgicos P2X3/metabolismo , Receptores Purinérgicos P2X7/metabolismo , Canales Catiónicos TRPV/metabolismo , Acetilcolina/farmacología , Adenosina Trifosfato/análogos & derivados , Adenosina Trifosfato/farmacología , Médula Suprarrenal/metabolismo , Médula Suprarrenal/patología , Animales , Capsaicina/farmacología , Catecolaminas/metabolismo , Células Cromafines/citología , Células Cromafines/efectos de los fármacos , Células Cromafines/metabolismo , Modelos Animales de Enfermedad , Potenciales Evocados/efectos de los fármacos , Exocitosis/efectos de los fármacos , Ganglios Espinales/patología , Ganglios Espinales/fisiología , Masculino , Potenciales de la Membrana/efectos de los fármacos , Neuralgia/metabolismo , Neuronas/patología , Neuronas/fisiología , Ratas , Ratas Sprague-Dawley , Receptores Purinérgicos P2X3/genética , Receptores Purinérgicos P2X7/genética , Canales Catiónicos TRPV/genética
12.
J Ethnopharmacol ; 233: 56-63, 2019 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-30599222

RESUMEN

ETHNOPHARMACOLOGICAL RELEVANCE: Strychnos nux-vomica L. (Loganiaceae) is grown extensively in South Asian. The dried seed of this plant, nux vomica, has been clinically used in Chinese medicine for relieving rheumatic pain, reducing swelling and treating cancer. Brucine, the second abundant alkaloid constituent of nux vomica, shows excellent clinical therapeutic effect, especially in relieving pain, but mechanism of brucine in relieving pain is still unclear. AIM OF THE STUDY: Explore the analgesic effect of brucine, reveal the molecular mechanism of brucine analgesia. MATERIALS AND METHODS: Antinociceptive effects of brucine were assessed in acute and chronic pain mice model. Electrophysiological experiments were used to evaluate the effects of brucine on neuronal activity and sodium channel function. RESULTS: In acute pain models, brucine significantly inhibits response induced by nociceptive heat and mechanical stimulation. Furthermore, thermal hypersensitivity and mechanical allodynia were also alleviated by brucine treatment in a chronic constriction injury (CCI) mouse model. Sodium channel plays a crucial role in neuropathic pain. Electrophysiological results show that brucine inhibits the excitability of DRG neurons directly, the number of action potential (AP) was significantly reduced after brucine treatment, and this kind of inhibition is due to brucine inhibits both tetrodotoxin-sensitive (TTXs) and tetrodotoxin-resistant (TTXr) sodium channel. CONCLUSIONS: Taken together, brucine is a novel drug candidate in treating acute and chronic pain diseases, which might be attributed to inhibition the excitability of sodium channel directly.


Asunto(s)
Analgésicos/farmacología , Analgésicos/uso terapéutico , Neuralgia/tratamiento farmacológico , Canales de Sodio/fisiología , Estricnina/análogos & derivados , Potenciales de Acción/efectos de los fármacos , Animales , Conducta Animal/efectos de los fármacos , Células Cultivadas , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/fisiología , Masculino , Ratones Endogámicos C57BL , Neuralgia/fisiopatología , Neuronas/efectos de los fármacos , Neuronas/fisiología , Estricnina/farmacología , Estricnina/uso terapéutico
13.
Biochem Biophys Res Commun ; 508(2): 348-353, 2019 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-30503336

RESUMEN

Electrical stimulation (ES) can be useful for promoting the regeneration of injured axons, but the mechanism underlying its positive effects is largely unknown. The current study aimed to investigate whether ES could enhance the regeneration of injured neurites in dorsal root ganglion explants and regulate the MMP-2 expression level, which is correlated with regeneration. Significantly increased neurite regeneration and MMP-2 expression was observed in the ES group compared with the sham group. However, an MMP inhibitor significantly decreased this ES-induced neurite regeneration. Our data suggest that the positive effect of ES on neurite regeneration could likely be mediated by an increase in MMP-2 expression, thereby promoting the regeneration of injured neurites.


Asunto(s)
Metaloproteinasa 2 de la Matriz/metabolismo , Regeneración Nerviosa/fisiología , Neuritas/fisiología , Animales , Axotomía , Dipéptidos/farmacología , Estimulación Eléctrica , Ganglios Espinales/citología , Ganglios Espinales/fisiología , Metaloproteinasa 9 de la Matriz/metabolismo , Inhibidores de la Metaloproteinasa de la Matriz/farmacología , Ratones , Ratones Endogámicos ICR , Regeneración Nerviosa/efectos de los fármacos , Neuritas/efectos de los fármacos , Técnicas de Cultivo de Tejidos , Regulación hacia Arriba
14.
ACS Appl Mater Interfaces ; 11(1): 356-372, 2019 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-30516370

RESUMEN

Magnetic electrospun fibers are of interest for minimally invasive biomaterial applications that also strive to provide cell guidance. Magnetic electrospun fibers can be injected and then magnetically positioned in situ, and the aligned fiber scaffolds provide consistent topographical guidance to cells. In this study, magnetically responsive aligned poly-l-lactic acid electrospun fiber scaffolds were developed and tested for neural applications. Incorporating oleic acid-coated iron oxide nanoparticles significantly increased neurite outgrowth, reduced the fiber alignment, and increased the surface nanotopography of the electrospun fibers. After verifying neuron viability on two-dimensional scaffolds, the system was tested as an injectable three-dimensional scaffold. Small conduits of aligned magnetic fibers were easily injected in a collagen or fibrinogen hydrogel solution and repositioned using an external magnetic field. The aligned magnetic fibers provided internal directional guidance to neurites within a three-dimensional collagen or fibrin model hydrogel, supplemented with Matrigel. Neurites growing from dorsal root ganglion explants extended 1.4-3× farther on the aligned fibers compared with neurites extending in the hydrogel alone. Overall, these results show that magnetic electrospun fiber scaffolds can be injected and manipulated with a magnetic field in situ to provide directional guidance to neurons inside an injectable hydrogel. Most importantly, this injectable guidance system increased both neurite alignment and neurite length within the hydrogel scaffold.


Asunto(s)
Ganglios Espinales/fisiología , Hidrogeles/química , Regeneración Nerviosa , Neuritas/metabolismo , Andamios del Tejido/química , Animales , Ganglios Espinales/citología , Ratas , Ratas Sprague-Dawley
16.
Neurosci Lett ; 694: 14-19, 2019 02 16.
Artículo en Inglés | MEDLINE | ID: mdl-30439399

RESUMEN

Chemotherapy-induced peripheral neuropathy (CIPN) is a severe and debilitating adverse effect of cancer therapy that results from treatment with neurotoxic agents. Although chemotherapy treatment has been shown to inhibit neurite outgrowth from dorsal root ganglion (DRG) neurons in vitro, evidence for this effect in vivo is lacking. In this study, we investigated whether chemotherapy treatment in mice alters the capacity for axonal outgrowth from ex vivo cultured DRG explants. Using a neurite outgrowth assay, we demonstrated that DRG explants isolated at day 30 from mice treated with 6 cycles of paclitaxel, or 12 cycles of oxaliplatin showed a significant reduction in neurite outgrowth as compared to DRG explants from control vehicle-treated mice. DRGs that were isolated at day 90 showed recovery of the neurite outgrowth, and no significant differences were detected in comparison to vehicle controls. These results are corroborated with an in vitro model, whereby direct application of oxaliplatin and paclitaxel dose-dependently reduced neurite outgrowth of DRG explants. In conclusion, our results show that the effect of paclitaxel and oxaliplatin on the structural plasticity of DRG is retained ex vivo (for at least 30 days) and suggest the use of DRG explants derived from chemotherapy-treated mice as an efficient method to investigate the mechanisms underlying CIPN and test for possible therapeutic targets.


Asunto(s)
Antineoplásicos/farmacología , Ganglios Espinales/efectos de los fármacos , Proyección Neuronal/efectos de los fármacos , Oxaliplatino/farmacología , Paclitaxel/farmacología , Animales , Antineoplásicos Fitogénicos/farmacología , Células Cultivadas , Relación Dosis-Respuesta a Droga , Ganglios Espinales/fisiología , Masculino , Ratones Endogámicos BALB C , Neuritas/efectos de los fármacos , Neuritas/fisiología , Plasticidad Neuronal/efectos de los fármacos
17.
J Clin Neurosci ; 59: 37-40, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30446365

RESUMEN

OBJECTIVE: To quantify the cross-sectional area (CSA) of lumbar dorsal root ganglion (DRG) by magnetic resonance imaging (MRI) and investigate the relationship between the cross-sectional area (CSA) of DRGs and sensory nerve action potentials (SNAP) amplitude in the lower extremities. METHODS: Thirty-eight DRGs (20 L5 roots and 18 S1 roots) in 10 adult subjects were reviewed retrospectively. The CSA of the DRG was calculated from MR images of the coronal plane. SNAP amplitudes of the superficial peroneal nerve and sural nerve were corresponded to L5 and S1-DRGs. RESULTS: The mean CSA of DRGs was 66.6 ±â€¯13.7 mm2 in L5-DRG and 79.5 ±â€¯14.3 mm2 in S1-DRG. The means of SNAP amplitudes were 19.6 ±â€¯6.2 µV in superficial peroneal nerves and 24.6 ±â€¯9.0 µV in sural nerves. In multivariate regression analysis, the CSA of DRGs had a significant correlation with SNAP amplitude. CONCLUSION: The area of L5 and S1-DRGs may be positively correlated with SNAP amplitude.


Asunto(s)
Potenciales de Acción , Ganglios Espinales/fisiología , Células Receptoras Sensoriales/fisiología , Adulto , Ganglios Espinales/diagnóstico por imagen , Humanos , Región Lumbosacra/diagnóstico por imagen , Región Lumbosacra/fisiología , Masculino , Persona de Mediana Edad
18.
J Pharmacol Exp Ther ; 368(1): 50-58, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30409832

RESUMEN

An injury of the somatosensory system causes neuropathic pain, which is usually refractory to conventional analgesics, thus warranting the development of novel drugs against this kind of pain. The mechanism of neuropathic pain in rats that had undergone left L5 spinal nerve transection was analyzed. Ten days after surgery, these rats acquired neuropathic pain. The patch-clamp technique was used on the isolated bilateral L5 dorsal root ganglion neurons. The current-clamped neurons on the ipsilateral side exhibited significantly higher excitability than those on the contralateral side. However, only neurons with diameters of 40-50 µm on the ipsilateral side exhibited significantly larger voltage sags in response to hyperpolarizing current pulses than those on the contralateral side. Under the voltage clamp, only these neurons on the ipsilateral side showed a significantly larger density of an inward current at < -80 mV [hyperpolarization-activated nonselective cation (I h) current] with a rightward-shifted activation curve than that on the contralateral side. Ivabradine-an I h current inhibitor-inhibited I h currents in these neurons on both sides in a similar concentration-dependent manner, with an IC50 value of ∼3 µM. Moreover, the oral administration of ivabradine significantly alleviated the neuropathic pain on the ipsilateral side. An inhibitor of adenylyl cyclase or an antagonist of prostanoid EP4 receptors (CJ-023423) inhibited ipsilateral, but not contralateral I h, currents in these neurons. Furthermore, the intrathecal administration of CJ-023423 significantly attenuated neuropathic pain on the ipsilateral side. Thus, ivabradine and/or CJ-023423 may be a lead compound for the development of novel therapeutics against neuropathic pain.


Asunto(s)
Ganglios Espinales/fisiología , Neuralgia/fisiopatología , Neuronas/fisiología , Subtipo EP4 de Receptores de Prostaglandina E/fisiología , Animales , Relación Dosis-Respuesta a Droga , Ganglios Espinales/efectos de los fármacos , Inyecciones Espinales , Ivabradina/administración & dosificación , Masculino , Potenciales de la Membrana/efectos de los fármacos , Potenciales de la Membrana/fisiología , Neuralgia/tratamiento farmacológico , Neuronas/efectos de los fármacos , Técnicas de Cultivo de Órganos , Ratas , Ratas Sprague-Dawley , Subtipo EP4 de Receptores de Prostaglandina E/antagonistas & inhibidores , Sulfonamidas/administración & dosificación
19.
Colloids Surf B Biointerfaces ; 173: 689-697, 2019 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-30384265

RESUMEN

Suitable micro/nanofibers orientation in tissue engineered scaffold could guide cells outgrowth and migration during tissue regeneration. However, it is still a challenge to prepare a simple, high-strength and aligned fibers scaffold. Herein, we report a facile strategy to construct high-strength silk fibroin (SF) scaffolds with aligned fibers orientation by crosslinking aligned SF fibers with regenerated SF solution for guiding neuronal growth direction. The fibers could be easily controlled within the same orientation. The aligned fibers and protein-protein interfacial bonding between SF fibers and regenerated SF solution reinforced the mechanical properties to form a high-strength scaffold. Schwann cells and dorsal root ganglion (DRG) neuron could migrate along with the uniform orientation of scaffolds. Mecobalamin was loaded into aligned SF scaffold to promote neurite growth and neuron survival through methylation cycle by activation of Erk1/2 and Akt. Additionally, mecobalamin loaded aligned SF scaffold demonstrated good biocompatibility, inflammatory cells also showed decreased profiles with time extensions. This facile strategy could enrich the fabrication methods to prepare aligned fibers scaffolds in the tissue engineering.


Asunto(s)
Fibroínas/química , Nanofibras/química , Ingeniería de Tejidos/métodos , Andamios del Tejido , Vitamina B 12/análogos & derivados , Animales , Bombyx , Movimiento Celular/efectos de los fármacos , Composición de Medicamentos/métodos , Liberación de Fármacos , Fibroínas/ultraestructura , Ganglios Espinales/citología , Ganglios Espinales/efectos de los fármacos , Ganglios Espinales/fisiología , Expresión Génica/efectos de los fármacos , Proteína Quinasa 1 Activada por Mitógenos/genética , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/genética , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Nanofibras/ultraestructura , Neuronas/citología , Neuronas/efectos de los fármacos , Neuronas/fisiología , Cultivo Primario de Células , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Conejos , Ratas , Ratas Sprague-Dawley , Células de Schwann/citología , Células de Schwann/efectos de los fármacos , Células de Schwann/fisiología , Resistencia a la Tracción , Vitamina B 12/química , Vitamina B 12/farmacología
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