Parvalbumin and TRPV1 receptor expression in dorsal root ganglion neurons after acute peripheral inflammation

Expression of parvalbumin (PV) and transient receptor potential vanilloid (TRPV1) receptors in the lumbar dorsal root ganglion neurons (DRG) was evaluated in control animals and in rats after acute carageenan-induced knee joint inflammation. PV is a calcium binding protein that acts as a calcium buffer, affects intracellular calcium homeostasis and may thus influence signal transduction and synaptic transmission. TRPV1 receptors are viewed as molecular integrators of nociceptive stimuli and modulate spinal cord synaptic transmission beside their function in the peripheral nerve endings. In naive rats, 13 % of the L4 DRG neurons had PV immunopositivity (PV+) and 36 % expressed TRPV1 receptors (TRPV1+). The soma of the PV+ neurons was of medium to large size, while the TRPV1 receptors were expressed in small diameter neurons. The co-localization of the PV and TRPV1 immunoreactivity was minimal (0.2 %). There was no significant change in the PV+ (11 %), TRPV1+ (42 %) and PV+TRPV1+ (0.25 %) expression, or shift in the neuronal size distribution 28 h after the unilateral peripheral inflammation, both when compared to controls and when ipsilateral to contralateral sides were evaluated. Thus under the given experimental conditions, no change in somatic TRPV1 receptors and PV expression in L4 DRG neurons was found.

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Long-Term Diabetic Microenvironment Augments the Decay Rate of Capsaicin-Induced Currents in Mouse Dorsal Root Ganglion Neurons

Molecules ◽

10.3390/molecules24040775 ◽

2019 ◽

Vol 24 (4) ◽

pp. 775

Author(s):

Xingjuan Chen ◽

Yaqian Duan ◽

Ashley Riley ◽

Megan Welch ◽

Fletcher White ◽

...

Keyword(s):

Peripheral Neuropathy ◽

Dorsal Root Ganglion ◽

Patch Clamp ◽

Dorsal Root ◽

Transient Receptor Potential ◽

Receptor Potential ◽

Dorsal Root Ganglion Neurons ◽

Transient Receptor Potential Vanilloid ◽

Drg Neurons ◽

Ganglion Neurons

Individuals with end-stage diabetic peripheral neuropathy present with decreased pain sensation. Transient receptor potential vanilloid type 1 (TRPV1) is implicated in pain signaling and resides on sensory dorsal root ganglion (DRG) neurons. We investigated the expression and functional activity of TRPV1 in DRG neurons of the Ins2+/Akita mouse at 9 months of diabetes using immunohistochemistry, live single cell calcium imaging, and whole-cell patch-clamp electrophysiology. 2′,7′-Dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence assay was used to determine the level of Reactive Oxygen Species (ROS) in DRGs. Although TRPV1 expressing neuron percentage was increased in Ins2+/Akita DRGs at 9 months of diabetes compared to control, capsaicin-induced Ca2+ influx was smaller in isolated Ins2+/Akita DRG neurons, indicating impaired TRPV1 function. Consistently, capsaicin-induced Ca2+ influx was decreased in control DRG neurons cultured in the presence of 25 mM glucose for seven days versus those cultured with 5.5 mM glucose. The high glucose environment increased cytoplasmic ROS accumulation in cultured DRG neurons. Patch-clamp recordings revealed that capsaicin-activated currents decayed faster in isolated Ins2+/Akita DRG neurons as compared to those in control neurons. We propose that in poorly controlled diabetes, the accelerated rate of capsaicin-sensitive TRPV1 current decay in DRG neurons decreases overall TRPV1 activity and contributes to peripheral neuropathy.

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Do distinct populations of dorsal root ganglion neurons account for the sensory peptidergic innervation of the kidney?

AJP Renal Physiology ◽

10.1152/ajprenal.90599.2008 ◽

2009 ◽

Vol 297 (5) ◽

pp. F1427-F1434 ◽

Cited By ~ 20

Author(s):

Tilmann Ditting ◽

Gisa Tiegs ◽

Kristina Rodionova ◽

Peter W. Reeh ◽

Winfried Neuhuber ◽

...

Keyword(s):

Dorsal Root Ganglion ◽

Dorsal Root ◽

Current Injection ◽

Dorsal Root Ganglion Neurons ◽

Transient Receptor Potential Vanilloid ◽

Drg Neurons ◽

Acid Sensitivity ◽

Trpv1 Channels ◽

Induced Currents ◽

Ganglion Neurons

Peptidergic afferent renal nerves (PARN) have been linked to kidney damage in hypertension and nephritis. Neither the receptors nor the signals controlling local release of neurokinines [calcitonin gene-related peptide (CGRP) and substance P (SP)] and signal transmission to the brain are well-understood. We tested the hypothesis that PARN, compared with nonrenal afferents (Non-RN), are more sensitive to acidic stimulation via transient receptor potential vanilloid type 1 (TRPV1) channels and exhibit a distinctive firing pattern. PARN were distinguished from Non-RN by fluorescent labeling (DiI) and studied by in vitro patch-clamp techniques in dorsal root ganglion neurons (DRG; T11-L2). Acid-induced currents or firing due to current injection or acidic superfusion were studied in 252 neurons, harvested from 12 Sprague-Dawley rats. PARN showed higher acid-induced currents than Non-RN (transient: 15.9 ± 5.1 vs. 0.4 ± 0.2* pA/pF at pH 6; sustained: 20.0 ± 4.5 vs. 6.2 ± 1.2* pA/pF at pH 5; * P < 0.05). The TRPV1 antagonist capsazepine inhibited sustained, amiloride-transient currents. Forty-eight percent of PARN were classified as tonic neurons (TN = sustained firing during current injection), and 52% were phasic (PN = transient firing). Non-RN were rarely tonic (15%), but more frequently phasic (85%), than PARN ( P < 0.001). TN were more frequently acid-sensitive than PN (50–70 vs. 2–20%, P < 0.01). Furthermore, renal PN were more frequently acid-sensitive than nonrenal PN (20 vs. 2%, P < 0.01). Confocal microscopy revealed innervation of renal vessels, tubules, and glomeruli by CGRP- and partly SP-positive fibers coexpressing TRPV1. Our data show that PARN are represented by a very distinct population of small-to-medium sized DRG neurons exhibiting more frequently tonic firing and TRPV1-mediated acid sensitivity. These very distinct DRG neurons might play a pivotal role in renal physiology and disease.

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Dorsal Root Ganglion Neurons Innervating Skeletal Muscle Respond to Physiological Combinations of Protons, ATP, and Lactate Mediated by ASIC, P2X, and TRPV1

Journal of Neurophysiology ◽

10.1152/jn.01344.2007 ◽

2008 ◽

Vol 100 (3) ◽

pp. 1184-1201 ◽

Cited By ~ 185

Author(s):

Alan R. Light ◽

Ronald W. Hughen ◽

Jie Zhang ◽

Jon Rainier ◽

Zhuqing Liu ◽

...

Keyword(s):

Skeletal Muscle ◽

Dorsal Root Ganglion ◽

Calcium Imaging ◽

Dorsal Root ◽

Dorsal Root Ganglion Neurons ◽

Drg Neurons ◽

Molecular Receptors ◽

Trpv1 Receptors ◽

Ganglion Neurons ◽

Two Populations

The adequate stimuli and molecular receptors for muscle metaboreceptors and nociceptors are still under investigation. We used calcium imaging of cultured primary sensory dorsal root ganglion (DRG) neurons from C57Bl/6 mice to determine candidates for metabolites that could be the adequate stimuli and receptors that could detect these stimuli. Retrograde DiI labeling determined that some of these neurons innervated skeletal muscle. We found that combinations of protons, ATP, and lactate were much more effective than individually applied compounds for activating rapid calcium increases in muscle-innervating dorsal root ganglion neurons. Antagonists for P2X, ASIC, and TRPV1 receptors suggested that these three receptors act together to detect protons, ATP, and lactate when presented together in physiologically relevant concentrations. Two populations of muscle-innervating DRG neurons were found. One responded to low metabolite levels (likely nonnoxious) and used ASIC3, P2X5, and TRPV1 as molecular receptors to detect these metabolites. The other responded to high levels of metabolites (likely noxious) and used ASIC3, P2X4, and TRPV1 as their molecular receptors. We conclude that a combination of ASIC, P2X5 and/or P2X4, and TRPV1 are the molecular receptors used to detect metabolites by muscle-innervating sensory neurons. We further conclude that the adequate stimuli for muscle metaboreceptors and nociceptors are combinations of protons, ATP, and lactate.

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Spinal PAR2 Activation Contributes to Hypersensitivity Induced by Peripheral Inflammation in Rats

International Journal of Molecular Sciences ◽

10.3390/ijms22030991 ◽

2021 ◽

Vol 22 (3) ◽

pp. 991

Author(s):

Petra Mrozkova ◽

Diana Spicarova ◽

Jiri Palecek

Keyword(s):

Synaptic Transmission ◽

Dorsal Horn ◽

Dorsal Root ◽

Transient Receptor Potential ◽

Thermal Hyperalgesia ◽

Dorsal Root Ganglion Neurons ◽

Peripheral Inflammation ◽

Transient Receptor Potential Vanilloid ◽

Behavioral Experiments ◽

Ganglion Neurons

The mechanisms of inflammatory pain need to be identified in order to find new superior treatments. Protease-activated receptors 2 (PAR2) and transient receptor potential vanilloid 1 (TRPV1) are highly co-expressed in dorsal root ganglion neurons and implicated in pain development. Here, we examined the role of spinal PAR2 in hyperalgesia and the modulation of synaptic transmission in carrageenan-induced peripheral inflammation, using intrathecal (i.t.) treatment in the behavioral experiments and recordings of spontaneous, miniature and dorsal root stimulation-evoked excitatory postsynaptic currents (sEPSCs, mEPSCs and eEPSCs) in spinal cord slices. Intrathecal PAR2-activating peptide (AP) administration aggravated the carrageenan-induced thermal hyperalgesia, and this was prevented by a TRPV1 antagonist (SB 366791) and staurosporine i.t. pretreatment. Additionally, the frequency of the mEPSC and sEPSC and the amplitude of the eEPSC recorded from the superficial dorsal horn neurons were enhanced after acute PAR2 AP application, while prevented with SB 366791 or staurosporine pretreatment. PAR2 antagonist application reduced the thermal hyperalgesia and decreased the frequency of mEPSC and sEPSC and the amplitude of eEPSC. Our findings highlight the contribution of spinal PAR2 activation to carrageenan-induced hyperalgesia and the importance of dorsal horn PAR2 and TRPV1 receptor interactions in the modulation of nociceptive synaptic transmission.

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On the inhibition of capsaicin response in dorsal root ganglion neurons by nobilamide B and analogues: a structure–activity relationship study

MedChemComm ◽

10.1039/c8md00304a ◽

2018 ◽

Vol 9 (10) ◽

pp. 1673-1678

Author(s):

Oliver John V. Belleza ◽

Jortan O. Tun ◽

Gisela P. Concepcion ◽

Aaron Joseph L. Villaraza

Keyword(s):

Dorsal Root Ganglion ◽

Primary Culture ◽

Dorsal Root ◽

Dorsal Root Ganglion Neurons ◽

Activity Relationship ◽

Drg Neurons ◽

Structure Activity ◽

Relationship Study ◽

Trpv1 Antagonist ◽

Ganglion Neurons

Nobilamide B, a TRPV1 antagonist, and a series of Ala-substituted analogues were synthesized and their neuroactivity was assessed in a primary culture of dorsal root ganglion (DRG) neurons.

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Variation in IH, IIR, and ILEAK between acutely isolated adult rat dorsal root ganglion neurons of different size

Journal of Neurophysiology ◽

10.1152/jn.1994.71.1.271 ◽

1994 ◽

Vol 71 (1) ◽

pp. 271-279 ◽

Cited By ~ 124

Author(s):

R. S. Scroggs ◽

S. M. Todorovic ◽

E. G. Anderson ◽

A. P. Fox

Keyword(s):

Dorsal Root Ganglion ◽

Action Potentials ◽

Dorsal Root ◽

Membrane Surface ◽

Small Diameter ◽

Reversal Potential ◽

Dorsal Root Ganglion Neurons ◽

Time Dependent ◽

Drg Neurons ◽

Ganglion Neurons

1. The distribution of IH, IIR, and ILEAK was studied in different diameter rat dorsal root ganglion (DRG) neuron cell bodies (neurons). DRG neurons were studied in three diameter ranges: small (19–27 microns), medium (33–37 microns), and large (44-54 microns). IH was defined as a slowly activating inward current evoked by hyperpolarizing voltage steps from a holding potential (HP) of -60 mV, and blocked by 1 mM Cs2+ but not 1 mM Ba2+. Inward rectifier current (IIR) was defined as a rapidly activating current evoked by hyperpolarizations from HP -60 mV, which rectified inwardly around the reversal potential for potassium (EK), and was completely blocked by 100 microM Ba2+. ILEAK was defined as an outward resting current at HP -60 mV, which did not rectify and was blocked by 100 microM Ba2+ but not by 2 mM Cs+. 2. IH was observed in 23 of 23 large, 11 of 12 medium, and in 9 of 20 small diameter DRG neurons tested. Peak IH normalized to membrane surface area was significantly greater in large than in medium or small diameter DRG neurons expressing IH. All neurons exhibiting IH under voltage clamp conditions had short duration action potentials and exhibited time-dependent rectification under current clamp conditions, properties similar to A-type DRG neurons. The 11 small diameter neurons not expressing IH had long duration action potentials and did not exhibit time-dependent rectification, properties similar to C-type DRG neurons. 3. IIR was detected in 18 of 22 medium diameter neurons tested.(ABSTRACT TRUNCATED AT 250 WORDS)

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An integrated cell isolation and purification method for rat dorsal root ganglion neurons

Journal of International Medical Research ◽

10.1177/0300060519855585 ◽

2019 ◽

Vol 47 (7) ◽

pp. 3253-3260

Author(s):

Huaishuang Shen ◽

Minfeng Gan ◽

Huilin Yang ◽

Jun Zou

Keyword(s):

Neuropathic Pain ◽

Dorsal Root Ganglion ◽

Primary Culture ◽

Dorsal Root ◽

Cell Isolation ◽

Dorsal Root Ganglion Neurons ◽

Drg Neurons ◽

Purification Method ◽

Isolation And Purification ◽

Ganglion Neurons

Objective Neurobiology studies are increasingly focused on the dorsal root ganglion (DRG), which plays an important role in neuropathic pain. Existing DRG neuron primary culture methods have considerable limitations, including challenging cell isolation and poor cell yield, which cause difficulty in signaling pathway studies. The present study aimed to establish an integrated primary culture method for DRG neurons. Methods DRGs were obtained from fetal rats by microdissection, and then dissociated with trypsin. The dissociated neurons were treated with 5-fluorouracil to promote growth of neurons from the isolated cells. Then, reverse transcription polymerase chain reaction and immunofluorescence assays were used to identify and purify DRG neurons. Results Isolated DRGs were successfully dissociated and showed robust growth as individual DRG neurons in neurobasal medium. Both mRNA and protein assays confirmed that DRG neurons expressed neurofilament-200 and neuron-specific enolase. Conclusions Highly purified, stable DRG neurons could be easily harvested and grown for extended periods by using this integrated cell isolation and purification method, which may help to elucidate the mechanisms underlying neuropathic pain.

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Interaction of opioids and membrane potential to modulate Ca2+ channels in rat dorsal root ganglion neurons

Journal of Neurophysiology ◽

10.1152/jn.1995.73.5.1793 ◽

1995 ◽

Vol 73 (5) ◽

pp. 1793-1798 ◽

Cited By ~ 22

Author(s):

M. D. Womack ◽

E. W. McCleskey

Keyword(s):

Dorsal Root Ganglion ◽

Sensory Neurons ◽

Action Potentials ◽

Dorsal Root ◽

Dorsal Root Ganglion Neurons ◽

High Threshold ◽

Partial Recovery ◽

Drg Neurons ◽

Ganglion Neurons ◽

Ca2 Channels

1. Using patch-clamp methods, we show that brief prepulses to very positive voltages increase (facilitate) the amplitude of current through Ca2+ channels during a subsequent test pulse in some, but not all, dorsal root ganglion (DRG) sensory neurons. The amplitude of this facilitated current generally increases when the Ca2+ channels are inhibited by activation of the mu-opioid receptor. 2. The facilitated current is blocked by omega-conotoxin GVIA, activates in the range of high-threshold Ca2+ channels, and inactivates at relatively negative holding voltages. Thus facilitated current passes through N-type Ca2+ channels, the same channels that are inhibited by opioids and control neurotransmitter release in sensory neurons. 3. Although maximal facilitation occurs only at unphysiologically high membrane potentials (above +100 mV), some facilitation is seen after prepulses to voltages reached during action potentials. After return to the holding potential, facilitation persists for hundreds of milliseconds, considerably longer than in other neurons. Brief trains of pulses designed to mimic action potentials caused small facilitation (19% of maximal) in a fraction (8 of 24) of opioid-inhibited neurons. 4. We conclude that 1) prepulses to extremely positive voltages can cause partial recovery of Ca2+ channels inhibited by opioids; and 2) small, but detectable, facilitation is also seen after physiological stimulation in some DRG neurons. Facilitation, largely considered a biophysical epiphenomenon because of the extreme voltages used to induce it, appears to be physiologically relevant during opioid inhibition of Ca2+ channels in DRG neurons.

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