scholarly journals Expression of sphingosine 1-phosphate receptors in the rat dorsal root ganglia and defined single isolated sensory neurons

2012 ◽  
Vol 44 (18) ◽  
pp. 889-901 ◽  
Author(s):  
J. S. Kays ◽  
Chao Li ◽  
G. D. Nicol
Keyword(s):  
Sensory Neurons ◽  
Dorsal Root ◽  
Neuronal Excitability ◽  
Expression Profiles ◽  
Large Diameter ◽  
Small Diameter ◽  
Positive Control ◽  
Single Neurons ◽  
Sphingosine 1 Phosphate ◽  
S1p Receptor

Previously, we demonstrated that sphingosine 1-phosphate (S1P) increased the excitability of small-diameter sensory neurons, in part, through activation of S1P receptor 1 (S1PR1), suggesting that other S1PRs can modulate neuronal excitability. Therefore, studies were undertaken to establish the expression profiles of S1PRs in the intact dorsal root ganglion (DRG) and in defined single isolated sensory neurons. To determine mRNA expression of S1PRs in the DRG, SYBR green quantitative PCR (qPCR) was used. To determine the expression of S1PR mRNAs in single neurons of defined diameters, a preamplification protocol utilizing Taqman primer and probes was used to enhance the sensitivity of detection. The preamplification protocol also permitted detection of mRNA for two hallmark neuronal receptor/ion channels, TRPV1 and P2X3. Expression profiles of S1PR mRNA isolated from lung and brain were used as positive control tissues. In the intact DRG, the order of expression of S1PRs was S1PR3>>R1≈R2>R5≈R4. In the single neurons, the expression of S1PRs was quite variable with some neurons expressing all five subtypes, whereas some expressing only one subtype. In contrast to the DRG, S1PR1 was the highest expressing subtype in 10 of the 18 small-, medium-, and large-diameter sensory neurons. S1PR1 was the second highest expressor in ∼50% of those remaining neurons. Overall, in the single neurons, the order of expression was S1PR1>>R3≈R5>R4>R2. The results obtained from the single defined neurons are consistent with our previous findings wherein S1PR1 plays a prominent but not exclusive role in the enhancement of neuronal excitability.

scholarly journals Sphingosine 1-phosphate receptor 2 antagonist JTE-013 increases the excitability of sensory neurons independently of the receptor

2012 ◽  
Vol 108 (5) ◽  
pp. 1473-1483 ◽  
Author(s):  
Chao Li ◽  
Xian Xuan Chi ◽  
Wenrui Xie ◽  
J. A. Strong ◽  
J.-M. Zhang ◽  
...  
Keyword(s):  
G Protein ◽  
Sensory Neurons ◽  
Neuronal Excitability ◽  
Small Diameter ◽  
G Protein Coupled Receptors ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Previously we demonstrated that sphingosine 1-phosphate receptor 1 (S1PR1) played a prominent, but not exclusive, role in enhancing the excitability of small-diameter sensory neurons, suggesting that other S1PRs can modulate neuronal excitability. To examine the potential role of S1PR2 in regulating neuronal excitability we used the established selective antagonist of S1PR2, JTE-013. Here we report that exposure to JTE-013 alone produced a significant increase in excitability in a time- and concentration-dependent manner in 70–80% of recorded neurons. Internal perfusion of sensory neurons with guanosine 5′- O-(2-thiodiphosphate) (GDP-β-S) via the recording pipette inhibited the sensitization produced by JTE-013 as well as prostaglandin E2. Pretreatment with pertussis toxin or the selective S1PR1 antagonist W146 blocked the sensitization produced by JTE-013. These results indicate that JTE-013 might act as an agonist at other G protein-coupled receptors. In neurons that were sensitized by JTE-013, single-cell RT-PCR studies demonstrated that these neurons did not express the mRNA for S1PR2. In behavioral studies, injection of JTE-013 into the rat's hindpaw produced a significant increase in the mechanical sensitivity in the ipsilateral, but not contralateral, paw. Injection of JTE-013 did not affect the withdrawal latency to thermal stimulation. Thus JTE-013 augments neuronal excitability independently of S1PR2 by unknown mechanisms that may involve activation of other G protein-coupled receptors such as S1PR1. Clearly, further studies are warranted to establish the causal nature of this increased sensitivity, and future studies of neuronal function using JTE-013 should be interpreted with caution.

Long-term IL-1β exposure causes subpopulation-dependent alterations in rat dorsal root ganglion neuron excitability

2012 ◽  
Vol 107 (6) ◽  
pp. 1586-1597 ◽  
Author(s):  
Patrick L. Stemkowski ◽  
Peter A. Smith
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Root Ganglion ◽  
Sensory Neurons ◽  
Dorsal Root ◽  
Large Diameter ◽  
Small Diameter ◽  
Defined Medium ◽  
Drg Neurons ◽  
Enriched Cultures

The effect of interleukin-1β (IL-1β) on the electrical properties of sensory neurons was assessed at levels and exposure times comparable to those found in animal models of neuropathic pain. Experiments involved whole cell current-clamp recordings from rat dorsal root ganglion (DRG) neurons in defined-medium, neuron-enriched cultures. Five- to six-day exposure to 100 pM IL-1β produced subpopulation-dependent effects on DRG neurons. These included an increase in the excitability of medium-diameter and small-diameter isolectin B4 (IB4)-positive neurons that was comparable to that found after peripheral nerve injury. By contrast, a reduction in excitability was observed in large-diameter neurons, while no effect was found in small-diameter IB4-negative neurons. Further characterization of changes in medium and small IB4-positive neurons revealed that some, but not all, effects of IL-1β were mediated through its receptor, IL-1RI. Although the acute actions of IL-1β on sensory neurons have been well studied and related to acute and/or inflammatory pain, the present study shows how sensory neurons respond to long-term cytokine exposure. Such effects are relevant to understanding processes that contribute to the onset of neuropathic pain.

Dorsal Root Ganglion Neuron Types and Their Functional Specialization

2018 ◽  
pp. 127-155 ◽  
Author(s):  
Edward C. Emery ◽  
Patrik Ernfors
Keyword(s):  
Chronic Pain ◽  
Dorsal Root Ganglion ◽  
Sensory Neurons ◽  
Dorsal Root ◽  
Molecular Mechanisms ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Drg Neurons ◽  
Low Threshold

Primary sensory neurons of the dorsal root ganglion (DRG) respond and relay sensations that are felt, such as those for touch, pain, temperature, itch, and more. The ability to discriminate between the various types of stimuli is reflected by the existence of specialized DRG neurons tuned to respond to specific stimuli. Because of this, a comprehensive classification of DRG neurons is critical for determining exactly how somatosensation works and for providing insights into cell types involved during chronic pain. This article reviews the recent advances in unbiased classification of molecular types of DRG neurons in the perspective of known functions as well as predicted functions based on gene expression profiles. The data show that sensory neurons are organized in a basal structure of three cold-sensitive neuron types, five mechano-heat sensitive nociceptor types, four A-Low threshold mechanoreceptor types, five itch-mechano-heat–sensitive nociceptor types and a single C–low-threshold mechanoreceptor type with a strong relation between molecular neuron types and functional types. As a general feature, each neuron type displays a unique and predicable response profile; at the same time, most neuron types convey multiple modalities and intensities. Therefore, sensation is likely determined by the summation of ensembles of active primary afferent types. The new classification scheme will be instructive in determining the exact cellular and molecular mechanisms underlying somatosensation, facilitating the development of rational strategies to identify causes for chronic pain.

scholarly journals ATP metabolizing enzymes ENPP1, 2 and 3 are localized in sensory neurons of rat dorsal root ganglion

2018 ◽  
Author(s):  
Kentaro Nishida ◽  
Yuka Nomura ◽  
Kanako Kawamori ◽  
Akihiro Ohishi ◽  
Kazuki Nagasawa
Keyword(s):  
Dorsal Root Ganglion ◽  
Sensory Neurons ◽  
Dorsal Root ◽  
Adenine Nucleotide ◽  
Expression Profiles ◽  
Critical Role ◽  
Immunohistochemical Analysis ◽  
Uptake System ◽  
Nucleoside Transporter ◽  
Drg Neurons

In dorsal root ganglion (DRG) neurons, ATP is an important neurotransmitter in nociceptive signaling through P2 receptors (P2Rs) such as P2X2/3R, and adenosine is also involved in anti-nociceptive signaling through adenosine A1R. Thus, the clearance system for adenine nucleotide/nucleoside plays a critical role in regulation of nociceptive signaling, but there is little information on it, especially ectoenzyme expression profiles in DRG. In this study, we examined expression and localization of ecto-nucleotide pyrophosphatase/phosphodiesterases (ENPPs), by which ATP is metabolized to AMP, in rat DRG. The mRNA expression levels of ENPP2 were greater than those of ENPP1 and ENPP3 in rat DRGs. On immunohistochemical analysis, ENPP1, 2 and 3 were found in soma of DRG neurons. Immunopositive rate of ENPP3 was greater than that of ENPP1 and ENPP2 in all DRG neurons. ENPP3, as compared with ENPP1 and ENPP2, was expressed mainly by isolectin B4-positive cells, and slightly by neurofilament 200-positive ones. In this way, the expression profile of ENPP1, 2 and 3 was different in DRGs, and they were mainly expressed in small/medium-sized DRG neurons. Moreover, ENPP1-, 2- and 3-immunoreactivities were colocalized with P2X2R, P2X3R and prostatic acid phosphatase (PAP), as an ectoenzyme for metabolism from AMP to adenosine. Additionally, PAP-immunoreactivity was colocalized with equilibrative nucleoside transporter (ENT) 1, as an adenosine uptake system. These results suggest that the clearance system consisted of ENPPs, PAP and ENT1 plays an important role in regulation of nociceptive signaling in sensory neurons.

scholarly journals Spatial transcriptomics reveals unique molecular fingerprints of human nociceptors

2021 ◽  
Author(s):  
Diana Tavares-Ferreira ◽  
Stephanie Shiers ◽  
Pradipta R. Ray ◽  
Andi Wangzhou ◽  
Vivekanand Jeevakumar ◽  
...  
Keyword(s):  
Sex Differences ◽  
Sensory Neurons ◽  
Dorsal Root ◽  
Expression Profiles ◽  
Organ Donors ◽  
Drg Neurons ◽  
Pain Mechanisms ◽  
Molecular Fingerprints ◽  
Sensory Disorders

AbstractSingle-cell transcriptomics on mouse nociceptors has transformed our understanding of pain mechanisms. Equivalent information from human nociceptors is lacking. We used spatial transcriptomics to molecularly characterize transcriptomes of single dorsal root ganglion (DRG) neurons from 8 organ donors. We identified 10 clusters of human sensory neurons, 6 of which are C nociceptors, 1 Aβ nociceptor, 1 Aδ, and 2 Aβ subtypes. These neuron subtypes have distinct expression profiles from rodents and non-human primates and we identify new markers for each of these subtypes that can be applied broadly in human studies. We also identify sex differences, including a marked increase in CALCA expression in female putative itch nociceptors. Our data open the door to new pain targets and unparalleled molecular characterization of clinical sensory disorders.One Sentence SummaryThree A-fiber mechanoreceptor and seven nociceptor subtypes are identified, revealing sex differences and unique aspects of human DRG neurons.

Sphingosine-1-Phosphate Via Activation of a G-Protein-Coupled Receptor(s) Enhances the Excitability of Rat Sensory Neurons

2006 ◽  
Vol 96 (3) ◽  
pp. 1042-1052 ◽  
Author(s):  
Y. H. Zhang ◽  
J. C. Fehrenbacher ◽  
M. R. Vasko ◽  
G. D. Nicol
Keyword(s):  
G Protein ◽  
Sensory Neurons ◽  
Small Diameter ◽  
G Protein Coupled Receptors ◽  
External Application ◽  
Nociceptive Neurons ◽  
Firing Threshold ◽  
Current Ramp ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Sphingosine-1-phosphate (S1P) is released by immune cells and is thought to play a key role in chemotaxis and the onset of the inflammatory response. The question remains whether this lipid mediator also contributes to the enhanced sensitivity of nociceptive neurons that is associated with inflammation. Therefore we examined whether S1P alters the excitability of small diameter, capsaicin-sensitive sensory neurons by measuring action potential (AP) firing and two of the membrane currents critical in regulating the properties of the AP. External application of S1P augments the number of APs evoked by a depolarizing current ramp. The enhanced firing is associated with a decrease in the rheobase and an increase in the resistance at firing threshold although neither the firing threshold nor the resting membrane potential are changed. Treatment with S1P enhanced the tetrodotoxin-resistant sodium current and decreased the total outward potassium current ( IK). When sensory neurons were internally perfused with GDP-β-S, a blocker of G protein activation, the S1P-induced increase in APs was completely blocked and suggests the excitatory actions of S1P are mediated through G-protein-coupled receptors called endothelial differentiation gene or S1PR. In contrast, internal perfusion with GDP-β-S and S1P increased the number of APs evoked by the current ramp. These results and our finding that the mRNAs for S1PRs are expressed in both the intact dorsal root ganglion and cultures of adult sensory neurons supports the notion that S1P acts on S1PRs linked to G proteins. Together these findings demonstrate that S1P can regulate the excitability of small diameter sensory neurons by acting as an external paracrine-type ligand through activation of G-protein-coupled receptors and thus may contribute to the hypersensitivity during inflammation.

scholarly journals The Chemokine CXCL1/Growth Related Oncogene Increases Sodium Currents and Neuronal Excitability in Small Diameter Sensory Neurons

2008 ◽  
Vol 4 ◽  
pp. 1744-8069-4-38 ◽  
Author(s):  
Jun-Gang Wang ◽  
Judith A Strong ◽  
Wenrui Xie ◽  
Rui-Hua Yang ◽  
Dennis E Coyle ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Neuronal Excitability ◽  
Small Diameter ◽  
Sodium Currents

Characterization of six voltage-gated K+ currents in adult rat sensory neurons

1996 ◽  
Vol 75 (6) ◽  
pp. 2629-2646 ◽  
Author(s):  
M. S. Gold ◽  
M. J. Shuster ◽  
J. D. Levine
Keyword(s):  
Action Potential ◽  
Sensory Neurons ◽  
Large Diameter ◽  
Small Diameter ◽  
Pharmacological Properties ◽  
Drg Neurons ◽  
Voltage Gated ◽  
Adult Rat ◽  
Whole Cell Patch Clamp ◽  
K Currents

1. Previously three voltage-gated K+ currents were described in neurons from mammalian sensory ganglia: two transient and one sustained. Because there is considerable variability in the gating properties of these three currents, we have investigated the possibility that this variability reflects the presence of additional currents in sensory neurons. 2. Using whole cell patch-clamp techniques, we provide evidence for the existence of six voltage-gated K+ currents in cultured dorsal root ganglion (DRG) neurons from the adult rat. The six currents were identified on the basis of distinct biophysical and pharmacological properties; three currents are transient (IAf, IAht, and IAs), and three are sustained (IKi, IKlt, and IKn). 3. In addition to possessing distinct biophysical and pharmacological properties, four of the six currents are differentially expressed among subpopulations of DRG neurons. IAht is selectively expressed in small-diameter neurons. IKi is expressed more frequently in neurons with an action-potential shoulder, and both IAht and IAs are selectively coexpressed in neurons that respond to the algogenic agent capsaicin. IAf is selectively expressed in large-diameter neurons and is the only current expressed more frequently in neurons without an action-potential shoulder. 4. It is likely that much of apparent variability in the properties of the three voltage-gated K+ currents reported previously in vertebrate sensory neurons can be accounted for by the existence of at least three additional voltage-gated K+ currents described in this report.

Allergic inflammation-induced neuropeptide production in rapidly adapting afferent nerves in guinea pig airways

2002 ◽  
Vol 282 (4) ◽  
pp. L775-L781 ◽  
Author(s):  
Allen C. Myers ◽  
Radhika Kajekar ◽  
Bradley J. Undem
Keyword(s):  
Substance P ◽  
Guinea Pig ◽  
Sensory Neurons ◽  
Large Diameter ◽  
Sensory System ◽  
Small Diameter ◽  
Allergic Inflammation ◽  
Primary Afferent ◽  
Chemical Coding ◽  
Low Threshold

In the vagal-sensory system, neuropeptides such as substance P and calcitonin gene-related peptide (CGRP) are synthesized nearly exclusively in small-diameter nociceptive type C-fiber neurons. By definition, these neurons are designed to respond to noxious or tissue-damaging stimuli. A common feature of visceral inflammation is the elevation in production of sensory neuropeptides. Little is known, however, about the physiological characteristics of vagal sensory neurons induced by inflammation to produce substance P. In the present study, we show that allergic inflammation of guinea pig airways leads to the induction of substance P and CGRP production in large-diameter vagal sensory neurons. Electrophysiological and anatomical evidence reveals that the peripheral terminals of these neurons are low-threshold Aδ mechanosensors that are insensitive to nociceptive stimuli such as capsaicin and bradykinin. Thus inflammation causes a qualitative change in chemical coding of vagal primary afferent neurons. The results support the hypothesis that during an inflammatory reaction, sensory neuropeptide release from primary afferent nerve endings in the periphery and central nervous system does not require noxious or nociceptive stimuli but may also occur simply as a result of stimulation of low-threshold mechanosensors. This may contribute to the heightened reflex physiology and pain that often accompany inflammatory diseases.

scholarly journals Mineralocorticoid Receptor Blocker Eplerenone Reduces Pain Behaviors In Vivo  and Decreases Excitability in Small-diameter Sensory Neurons from Local Inflamed Dorsal Root Ganglia In Vitro 

2012 ◽  
Vol 117 (5) ◽  
pp. 1102-1112 ◽  
Author(s):  
Fei Dong ◽  
Wenrui Xie ◽  
Judith A. Strong ◽  
Jun-Ming Zhang
Keyword(s):  
Sensory Neurons ◽  
Dorsal Root Ganglia ◽  
Dorsal Root ◽  
Mineralocorticoid Receptor ◽  
Small Diameter ◽  
Mechanical Hypersensitivity ◽  
Proinflammatory Role ◽  
Immunohistochemical Studies

Background Inflammation of the dorsal root ganglia (DRG) may contribute to low back pain, postherpetic neuralgia, and neuropathic pain. The mineralocorticoid receptor (MR) plays a proinflammatory role in many nonrenal tissues, but its role in peripheral pain at the DRG level is not well studied. Methods Local inflammation of the L5 DRG with the immune activator zymosan rapidly leads to mechanical hypersensitivity and increased excitability of sensory neurons. Using this pain model, the authors applied the MR antagonist eplerenone locally to the inflamed DRG. Excitability of small-diameter sensory neurons was examined in acute primary culture by using patch clamp techniques. Results Local eplerenone significantly reduced the mechanical hypersensitivity and shortened its duration. The same dose was ineffective systemically. Immunohistochemical studies showed the MR was present in most neurons and rapidly translocated to the nucleus 1 day after local DRG inflammation. Activation of satellite glia (defined by expression of glial fibrillary acidic protein) in the inflamed DRG was also reduced by local eplerenone. Increased excitability of small-diameter sensory neurons 1 day after inflammation could be observed in vitro. Eplerenone applied in vitro (8-12 h) could reverse this increased excitability. Eplerenone had no effect in neurons isolated from normal, uninflamed DRG. The MR agonist aldosterone (10 nM) applied in vitro increased excitability of neurons isolated from normal DRG. Conclusions The MR may have a pronociceptive role in the DRG. Some of its effects may be mediated by neuronal MR. The MR may represent a novel therapeutic target in some pain syndromes.

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