Su1947 Mesotrypsin Evokes PAR2 Dependent Excitabilty of Nociceptive Dorsal Root Ganglia (DRG) Neurons

Dorsal root ganglia (DRG) neurons synthesize acetylcholine (ACh), in addition to their peptidergic nature. They also release ACh and are cholinoceptive, as they express cholinergic receptors. During gangliogenesis, ACh plays an important role in neuronal differentiation, modulating neuritic outgrowth and neurospecific gene expression. Starting from these data, we studied the expression of choline acetyltransferase (ChAT) and vesicular ACh transporter (VAChT) expression in rat DRG neurons. ChAT and VAChT genes are arranged in a “cholinergic locus”, and several splice variants have been described. Using selective primers, we characterized splice variants of these cholinergic markers, demonstrating that rat DRGs express R1, R2, M, and N variants for ChAT and V1, V2, R1, and R2 splice variants for VAChT. Moreover, by RT-PCR analysis, we observed a progressive decrease in ChAT and VAChT transcripts from the late embryonic developmental stage (E18) to postnatal P2 and P15 and in the adult DRG. Interestingly, Western blot analyses and activity assays demonstrated that ChAT levels significantly increased during DRG ontogenesis. The modulated expression of different ChAT and VAChT splice variants during development suggests a possible differential regulation of cholinergic marker expression in sensory neurons and confirms multiple roles for ACh in DRG neurons, both in the embryo stage and postnatally.

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

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00028.2005 ◽

2005 ◽

Vol 289 (4) ◽

pp. G670-G678 ◽

Cited By ~ 36

Author(s):

Tian-Ying Huang ◽

Menachem Hanani

Keyword(s):

Glial Cells ◽

Dorsal Root Ganglia ◽

Dorsal Root ◽

Neuronal Excitability ◽

Colonic Obstruction ◽

Resting Potential ◽

Dye Coupling ◽

Drg Neurons ◽

Satellite Glial Cells ◽

Colon Wall

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.

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Suppression of KCNQ/M Potassium Channel in Dorsal Root Ganglia Neurons Contributes to the Development of Osteoarthritic Pain

Pharmacology ◽

10.1159/000496422 ◽

2019 ◽

Vol 103 (5-6) ◽

pp. 257-262 ◽

Cited By ~ 3

Author(s):

Fan Zhang ◽

Yani Liu ◽

Dandan Zhang ◽

Xizhenzi Fan ◽

Decheng Shao ◽

...

Keyword(s):

Dorsal Root Ganglia ◽

Dorsal Root ◽

Strong Impact ◽

Drg Neurons ◽

M Current ◽

Mechanical Threshold ◽

Dorsal Root Ganglia Neurons ◽

M Channels ◽

Osteoarthritic Pain

Osteoarthritic pain has a strong impact on patients’ quality of life. Understanding the pathogenic mechanisms underlying osteoarthritic pain will likely lead to the development of more effective treatments. In the present study of osteoarthritic model rats, we observed a reduction of M-current density and a remarkable decrease in the levels of KCNQ2 and KCNQ3 proteins and mRNAs in dorsal root ganglia (DRG) neurons, which were associated with hyperalgesic behaviors. The activation of KCNQ/M channels with flupirtine significantly increased the mechanical threshold and prolonged the withdrawal latency of osteoarthritic model rats at 3–14 days after model induction, and all effects of flupirtine were blocked by KCNQ/M-channel antagonist, XE-991. Together, these results indicate that suppression of KCNQ/M channels in primary DRG neurons plays a crucial role in the development of osteoarthritic pain.

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W1709 Bacterial Cell Products Increase Excitability of Mouse Colonic Nociceptive Dorsal Root Ganglia (DRG) Neurons

Gastroenterology ◽

10.1016/s0016-5085(09)63332-1 ◽

2009 ◽

Vol 136 (5) ◽

pp. A-722

Author(s):

Fernando Ochoa-Cortes ◽

Ian Spreadbury ◽

Carlos Barajas-Lopez ◽

Stephen J. Vanner

Keyword(s):

Dorsal Root Ganglia ◽

Bacterial Cell ◽

Dorsal Root ◽

Drg Neurons

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Localization of P2X and P2Y Receptors in Dorsal Root Ganglia of the Cat

Journal of Histochemistry & Cytochemistry ◽

10.1369/jhc.4a6556.2005 ◽

2005 ◽

Vol 53 (10) ◽

pp. 1273-1282 ◽

Cited By ~ 32

Author(s):

Huai-Zhen Ruan ◽

Lori A. Birder ◽

William C. de Groat ◽

Changfeng Tai ◽

James Roppolo ◽

...

Keyword(s):

Dorsal Root Ganglia ◽

Dorsal Root ◽

Polyclonal Antibodies ◽

Small Diameter ◽

P2y Receptors ◽

Receptor Subtypes ◽

P2y Receptor ◽

Drg Neurons ◽

Double Labeling ◽

Medium Diameter

The distribution of P2X and P2Y receptor subtypes in upper lumbosacral cat dorsal root ganglia (DRG) has been investigated using immunohistochemistry. Intensity of immunoreactivity for six P2X receptors (P2X5 receptors were immuno-negative) and the three P2Y receptors examined in cat DRG was in the order of P2Y2 = P2Y4>P2X3>P2X2 = P2X7>P2X6>P2X1 = P2X4>P2Y1. P2X3, P2Y2, and P2Y4 receptor polyclonal antibodies stained 33.8%, 35.3%, and 47.6% of DRG neurons, respectively. Most P2Y2, P2X1, P2X3, P2X4, and P2X6 receptor staining was detected in small- and medium-diameter neurons. However, P2Y4, P2X2, and P2X7 staining was present in large- and small-diameter neurons. Double-labeling immunohistochemistry showed that 90.8%, 32.1%, and 2.4% of P2X3 receptor-positive neurons coexpressed IB4, CGRP, and NF200, respectively; whereas 67.4%, 41.3%, and 39.1% of P2Y4 receptor-positive neurons coexpressed IB4, CGRP, and NF200, respectively. A total of 18.8%, 16.6%, and 63.5% of P2Y2 receptor-positive neurons also stained for IB4, CGRP, and NF200, respectively. Only 30% of DRG neurons in cat were P2X3-immunoreactive compared with 90% in rat and in mouse. A further difference was the low expression of P2Y1 receptors in cat DRG neurons compared with more than 80% of the neurons in rat. Many small-diameter neurons were NF200-positive in cat, again differing from rat and mouse.

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Electroacupuncture Reduces Carrageenan- and CFA-Induced Inflammatory Pain Accompanied by Changing the Expression of Nav1.7 and Nav1.8, rather than Nav1.9, in Mice Dorsal Root Ganglia

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2013/312184 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 11

Author(s):

Chun-Ping Huang ◽

Hsiang-Ni Chen ◽

Hong-Lin Su ◽

Ching-Liang Hsieh ◽

Wei-Hsin Chen ◽

...

Keyword(s):

Sodium Channels ◽

Dorsal Root Ganglia ◽

Inflammatory Pain ◽

Dorsal Root ◽

Low Frequency ◽

Thermal Hyperalgesia ◽

Nerve Fibers ◽

Drg Neurons ◽

Plantar Surface ◽

Voltage Gated Sodium Channels

Several voltage-gated sodium channels (Navs) from nociceptive nerve fibers have been identified as important effectors in pain signaling. The objective of this study is to investigate the electroacupuncture (EA) analgesia mechanism by changing the expression of Navs in mice dorsal root ganglia (DRG). We injected carrageenan and complete Freund's adjuvant (CFA) into the mice plantar surface of the hind paw to induce inflammation and examined the antinociception effect of EA at the Zusanli (ST36) acupoint at 2 Hz low frequency. Mechanical hyperalgesia was evaluated by using electronic von Frey filaments, and thermal hyperalgesia was assessed using Hargreaves' test. Furthermore, we observed the expression and quality of Navs in DRG neurons. Our results showed that EA reduced mechanical and thermal pain in inflammatory animal model. The expression of Nav1.7 and Nav1.8 was increased after 4 days of carrageenan- and CFA-elicited inflammatory pain and further attenuated by 2 Hz EA stimulation. The attenuation cannot be observed in Nav1.9 sodium channels. We demonstrated that EA at Zusanli (ST36) acupoint at 2 Hz low-frequency stimulation attenuated inflammatory pain accompanied by decreasing the expression of Nav1.7 and 1.8, rather than Nav1.9, sodium channels in peripheral DRG neurons.

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Despite Differences in Cytosolic Calcium Regulation, Lidocaine Toxicity Is Similar in Adult and Neonatal Rat Dorsal Root Ganglia In Vitro

Anesthesiology ◽

10.1097/aln.0b013e3182a2a561 ◽

2014 ◽

Vol 120 (1) ◽

pp. 50-61 ◽

Cited By ~ 9

Author(s):

Lisa V. Doan ◽

Olga Eydlin ◽

Boris Piskoun ◽

Richard P. Kline ◽

Esperanza Recio-Pinto ◽

...

Keyword(s):

Dorsal Root Ganglia ◽

Local Anesthetics ◽

Dorsal Root ◽

Caspase 3 ◽

Cytosolic Calcium ◽

Neonatal Rat ◽

Dependent Manner ◽

Drg Neurons ◽

Induced Changes

Abstract Background: Neuraxial local anesthetics may have neurological complications thought to be due to neurotoxicity. A primary site of action of local anesthetics is the dorsal root ganglia (DRG) neuron. Physiologic differences have been noted between young and adult DRG neurons; hence, the authors examined whether there were any 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.

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Cis and trans RET signaling control the survival and central projection growth of rapidly adapting mechanoreceptors

eLife ◽

10.7554/elife.06828 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 16

Author(s):

Michael S Fleming ◽

Anna Vysochan ◽

Sόnia Paixão ◽

Jingwen Niu ◽

Rüdiger Klein ◽

...

Keyword(s):

Cell Survival ◽

Dorsal Root Ganglia ◽

Dorsal Root ◽

Developmental Process ◽

Central Projection ◽

Drg Neurons ◽

In Trans ◽

Cis And Trans ◽

In Cis

RET can be activated in cis or trans by its co-receptors and ligands in vitro, but the physiological roles of trans signaling are unclear. Rapidly adapting (RA) mechanoreceptors in dorsal root ganglia (DRGs) express Ret and the co-receptor Gfrα2 and depend on Ret for survival and central projection growth. Here, we show that Ret and Gfrα2 null mice display comparable early central projection deficits, but Gfrα2 null RA mechanoreceptors recover later. Loss of Gfrα1, the co-receptor implicated in activating RET in trans, causes no significant central projection or cell survival deficit, but Gfrα1;Gfrα2 double nulls phenocopy Ret nulls. Finally, we demonstrate that GFRα1 produced by neighboring DRG neurons activates RET in RA mechanoreceptors. Taken together, our results suggest that trans and cis RET signaling could function in the same developmental process and that the availability of both forms of activation likely enhances but not diversifies outcomes of RET signaling.

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