scholarly journals Improving NKCC1 Function Increases the Excitability of DRG Neurons Exacerbating Pain Induced After TRPV1 Activation of Primary Sensory Neurons

2021 ◽  
Vol 15 ◽  
Author(s):  
Shi-Yu Deng ◽  
Xue-Chun Tang ◽  
Yue-Chen Chang ◽  
Zhen-Zhen Xu ◽  
Qin-Yi Chen ◽  
...  
Keyword(s):  
Protein Expression ◽  
Inflammatory Pain ◽  
Transient Receptor Potential ◽  
Intrathecal Injection ◽  
Chloride Concentration ◽  
Receptor Potential ◽  
Control Group ◽  
Noxious Stimulation ◽  
Transient Receptor Potential Vanilloid ◽  
Sprague Dawley

Background Our aim was to investigate the effects of the protein expression and the function of sodium, potassium, and chloride co-transporter (NKCC1) in the dorsal root ganglion (DRG) after activation of transient receptor potential vanilloid 1 receptor (TRPV1) in capsaicin-induced acute inflammatory pain and the possible mechanism of action.Methods Male Sprague–Dawley rats were randomly divided into control, capsaicin, and inhibitor groups. The expression and distribution of TRPV1 and NKCC1 in rat DRG were observed by immunofluorescence. Thermal radiation and acetone test were used to detect the pain threshold of heat and cold noxious stimulation in each group. The expressions of NKCC1 mRNA, NKCC1 protein, and p-NKCC1 in the DRG were detected by PCR and western blotting (WB). Patch clamp and chloride fluorescent probe were used to observe the changes of GABA activation current and intracellular chloride concentration. After intrathecal injection of protein kinase C (PKC) inhibitor (GF109203X) or MEK/extracellular signal-regulated kinase (ERK) inhibitor (U0126), the behavioral changes and the expression of NKCC1 and p-ERK protein in L4–6 DRG were observed.Result: TRPV1 and NKCC1 were co-expressed in the DRG. Compared with the control group, the immunofluorescence intensity of NKCC1 and p-NKCC1 in the capsaicin group was significantly higher, and the expression of NKCC1 in the nuclear membrane was significantly higher than that in the control group. The expression of NKCC1 mRNA and protein of NKCC1 and p-NKCC1 in the capsaicin group were higher than those in the control group. After capsaicin injection, GF109203X inhibited the protein expression of NKCC1 and p-ERK, while U0126 inhibited the protein expression of NKCC1. In the capsaicin group, paw withdrawal thermal latency (WTL) was decreased, while cold withdrawal latency (CWL) was prolonged. Bumetanide, GF109203X, or U0126 could reverse the effect. GABA activation current significantly increased in the DRG cells of the capsaicin group, which could be reversed by bumetanide. The concentration of chloride in the DRG cells of the capsaicin group increased, but decreased after bumetanide, GF109203X, and U0126 were administered.Conclusion Activation of TRPV1 by exogenous agonists can increase the expression and function of NKCC1 protein in DRG, which is mediated by activation of PKC/p-ERK signaling pathway. These results suggest that DRG NKCC1 may participate in the inflammatory pain induced by TRPV1.

scholarly journals Antinociceptive Effects of Emodin on CFA-Induced Inflammatory Pain in Rats

2020 ◽  
Vol 15 (7) ◽  
pp. 1934578X2094200
Author(s):  
Wan Ni ◽  
Nianyun Wang ◽  
Shenglan Tian ◽  
Qingbang Xu
Keyword(s):  
Mrna Expression ◽  
Inflammatory Pain ◽  
Transient Receptor Potential ◽  
Interleukin 1 ◽  
Receptor Potential ◽  
Enzyme Linked Immunosorbent Assay ◽  
Control Group ◽  
Transient Receptor Potential Vanilloid ◽  
Tnf Α ◽  
Transient Receptor

The effect of emodin on complete Freund’s adjuvant (CFA)-induced inflammatory pain in rats and its potential molecular mechanism was investigated. For this, a rat model of inflammatory pain induced by CFA was established and rats were treated with emodin by intraperitoneal injection. The pain threshold was evaluated by the von Frey, thermo hyperalgesia, and cold plate tests. The mRNA expression of transient receptor potential channel ankyrin type-1 ( Trpa1) and transient receptor potential vanilloid 1 ( Trpv1) was detected by quantitative reverse transcription polymerase chain reaction, and the level of inflammatory cytokines was determined by enzyme-linked immunosorbent assay. The mechanical and thermal pain thresholds of CFA-treated rats were significantly lower than those of the control rats, while the paw withdrawal responses in response to cold stimulation were higher than that of the control group. Emodin treatment significantly improved CFA-induced hyperalgesia. Further results showed that emodin inhibits the upregulation of Trpa1 and Trpv1 mRNA expression in the dorsal root ganglion (DRG) of rats with inflammatory pain compared with the control group. Emodin also significantly reduced the levels of tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6) in the serum of rats with inflammatory pain. Thus, emodin may inhibit hyperalgesia induced by inflammatory stimulation by downregulating the mRNA expression of Trpa1 and Trpv1 in DRG neurons and reducing the levels of TNF-α, IL-1β, and IL-6.

Effects of low- and high-frequency electroacupuncture on protein expression and distribution of TRPV1 and P2X3 in rats with peripheral nerve injury

2020 ◽  
pp. 096452842096884
Author(s):  
Junying Du ◽  
Junfan Fang ◽  
Xuaner Xiang ◽  
Jie Yu ◽  
Xiaoqin Le ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Protein Expression ◽  
Nerve Injury ◽  
Transient Receptor Potential ◽  
Intrathecal Injection ◽  
Receptor Potential ◽  
P2x Receptor ◽  
Sprague Dawley ◽  
Withdrawal Threshold ◽  
Analgesic Effects

Background: Whether electroacupuncture (EA) stimulation at different frequencies has a similar effect on spared nerve injury (SNI) as other neuropathic pain models, and how EA at different frequencies causes distinct analgesic effects on neuropathic pain is still not clear. Methods: Adult male Sprague-Dawley rats were randomly divided into sham SNI, SNI, 2 Hz, 100 Hz and sham EA groups. Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were measured. EA was performed once a day on days 1 to 14 after SNI. The expressions of transient receptor potential cation subfamily V member 1 (TRPV1) and peripheral purinergic P2X receptor 3 (P2X3) were determined by western blotting and immunofluorescence. TRPV1 siRNA and P2X3 siRNA were administered by intrathecal injection. TRPV1 or P2X3 agonists were combined with EA. Results: There were significant decreases in PWT, but no changes in PWL in the 14 days after SNI. EA using 2- or 100-Hz stimulation similarly increased PWT at every time point. The cytosol protein expression of P2X3 in the L4–L6 dorsal root ganglia (DRG) increased, but the expression of TRPV1 decreased in the SNI model. Both these effects were ameliorated by EA, with 2-Hz stimulation having a stronger effect than 100-Hz stimulation. Blocking either TRPV1 or P2X3 specific siRNAs attenuated the decreased PWT induced by SNI. Administration of either a TRPV1 or P2X3 agonist inhibited EA analgesia. Conclusion: 2- and 100-Hz EA similarly induced analgesic effects in SNI. This effect was related to up-regulation and down-regulation, respectively, of cytosol protein expression of P2X3 and TRPV1 in L4–L6 DRG, with 2 Hz having a better effect than 100 Hz.

Abstract 115: Reduction of Trpv1 Activity in Aortic Baroreceptor Neurons in Diabetic Neuropathy: Role of Brain-derived Neurotrophic Factor

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Yingying Tan ◽  
Qi Zhang
Keyword(s):  
Diabetic Neuropathy ◽  
Transient Receptor Potential ◽  
Kinase Inhibitor ◽  
Receptor Potential ◽  
Diabetic Rats ◽  
Control Group ◽  
Transient Receptor Potential Vanilloid ◽  
Peak Current Density ◽  
Inward Current ◽  
Pre Treatment

It has been well documented that diabetes mellitus is associated with cardiovascular autonomic neuropathy including dysfunction of arterial baroreflex. The mechanisms underlying diabetes-induced baroreflex dysfunction remain poorly understood. Here we investigated the function and expression of transient receptor potential vanilloid 1 (TRPV1) in aortic baroreceptor (AB) neurons isolated from streptozotocin-induced diabetic rats between 4 and 8 weeks after onset of diabetes. AB neurons in nodose ganglion were retrograde-labeled by a transported fluorescent dye, Dil. Using the whole-cell patch clamp, we found that the inward current activated by the application of capsaicin (1 μM) was significantly smaller in AB neurons from diabetic rats compared with controls. The mean peak current density of capsaicin-induced currents was 145.7 ± 24.7 pA/pF (n = 16) in diabetic neurons and 269.3 ± 31.8 pA/pF (n =15) in controls, respectively. The duration of inward current was decreased 51% in diabetic rats compared with the control group. These evoked currents were completely blocked by the capsaicin antagonist capsazepine. In addition, capsaicin-induced desensitization of TRPV1 was up-regulated, whereas TRPV1 re-sensitization was down-regulated in AB neurons from diabetic rats. Immunofluorescence staining studies demonstrated that the percentage of TRPV1-positive neurons was 50.2 ± 5.0% in control rats and 38.2 ± 1.9% in diabetic rats, respectively. This reduction in TRPV1-positive neurons in AB neurons in diabetic rats was significant (n = 11, P < 0.01). In addition, the reductions in TRPV1 currents and positive neurons s in diabetic rats were normalized by pre-treatment with anti-BDNF antibody or K252a, a TrkB tyrosine kinase inhibitor. Furthermore, incubation with BDNF caused a large reduction in TRPV1 currents in AB neurons from control rats, and the number of AB neurons with BDNF immunoreactivity was greater in diabetic than control rats. These results suggest that reduced expression and function of TRPV1 are involved in the attenuation of baroreceptor neuron excitability, and increased BDNF activity in these neurons likely contributes to the reduction in TRPV1 function through TrkB receptor stimulation in diabetic neuropathy.

scholarly journals RSV infection potentiates TRPV1-mediated calcium transport in bronchial epithelium of asthmatic children

2021 ◽  
Author(s):  
Terri J Harford ◽  
Lisa Grove ◽  
Fariba Rezaee ◽  
Rachel Greenberg Scheraga ◽  
Mitchell A. Olman ◽  
...  
Keyword(s):  
Protein Expression ◽  
Plasma Membranes ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Bronchial Epithelium ◽  
Transient Receptor Potential Vanilloid ◽  
Mucus Production ◽  
Asthmatic Children ◽  
Rsv Infection ◽  
And Function

Rationale: The transient receptor potential vanilloid 1 (TRPV1) channel is expressed in human bronchial epithelium (HBE), where it transduces Ca2+ in response to airborne irritants. TRPV1 activation results in bronchoconstriction, cough, and mucus production, and may therefore contribute to the pathophysiology of obstructive airway disease. Since asthmatic children face the greatest risk of developing virus-induced airway obstruction, we hypothesized that changes in TRPV1 expression, localization, and function in airway epithelium may play a role in bronchiolitis and asthma in childhood. Objectives: We sought to measure TRPV1 protein expression, localization, and function in HBE cells from asthmatic vs. non-asthmatic children both at baseline and after RSV infection. Methods: We determined changes in TRPV1 protein expression, subcellular localization, and function both at baseline and after RSV infection in primary HBE cells from normal and asthmatic children. Results: Basal TRPV1 protein expression was higher in HBE from asthmatic vs. non-asthmatic children and primarily localized to plasma membranes (PM). During RSV infection, TRPV1 protein increased more in the PM of asthmatic HBE as compared to non-asthmatic cells. TRPV1-mediated increase in intracellular Ca2+ was greater in RSV-infected asthmatic cells, but this increase was attenuated when extracellular Ca2+ was removed. Nerve growth factor (NGF) recapitulated the effect of RSV on TRPV1 activation in HBE cells. Conclusions: Our data suggest that asthmatic children have intrinsically hyperreactive airways due in part to higher TRPV1-mediated Ca2+ influx across epithelial membranes, and this abnormality is further exacerbated by NGF overexpression during RSV infection driving additional Ca2+ from intracellular stores.

scholarly journals Electroacupuncture inhibits the interaction between peripheral TRPV1 and P2X3 in rats with different pathological pain

2021 ◽  
Vol 70 (4) ◽  
pp. 635-647
Author(s):  
Yingjun Liu ◽  
Junying Du ◽  
Junfan Fang ◽  
Xuaner Xiang ◽  
Yingling Xu ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Inflammatory Pain ◽  
Transient Receptor Potential ◽  
Subcutaneous Administration ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Spontaneous Pain ◽  
Physical Interaction ◽  
Expression Ratio ◽  
Pathological Pain

Chronic pain is regarded to be one of the common and refractory diseases to cure in the clinic. One hundred Hz electroacupuncture (EA) is commonly used for inflammatory pain and 2 Hz for neuropathic pain possibly by modulating the transient receptor potential vanilloid subtype 1 (TRPV1) or the purinergic P2X3 related pathways. To clarify the mechanism of EA under various conditions of pathological pain, rats received a subcutaneous administration of complete Freund’s adjuvant (CFA) for inflammatory pain and spared nerve injury (SNI) for neuropathic pain. The EA was performed at the bilateral ST36 and BL60 1 d after CFA or SNI being successfully established for 3 consecutive days. The mechanical hyperalgesia test was measured at baseline, 1 d after model establishment, 1 d and 3 d after EA. The co-expression changes, co-immunoprecipitation of TRPV1 and P2X3, and spontaneous pain behaviors (SPB) test were performed 3 d after EA stimulation. One hundred Hz EA or 2Hz EA stimulation could effectively down-regulate the hyperalgesia of CFA or SNI rats. The increased co-expression ratio between TRPV1 and P2X3 at the dorsal root ganglion (DRG) in two types of pain could be reduced by 100Hz or 2Hz EA intervention. While 100Hz or 2Hz EA was not able to eliminate the direct physical interaction between TRPV1 and P2X3. Moreover, EA could significantly inhibit the SPB induced by the co-activation of peripheral TRPV1 and P2X3. All results indicated that EA could significantly reduce the hyperalgesia and the SPB, which was partly related to inhibiting the co-expression and indirect interaction between peripheral TRPV1 and P2X3.

scholarly journals Resolvin D1 and D2 Inhibit Transient Receptor Potential Vanilloid 1 and Ankyrin 1 Ion Channel Activation on Sensory Neurons via Lipid Raft Modification

2020 ◽  
Vol 21 (14) ◽  
pp. 5019
Author(s):  
Maja Payrits ◽  
Ádám Horváth ◽  
Tünde Biró-Sütő ◽  
János Erostyák ◽  
Géza Makkai ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Lipid Raft ◽  
Cho Cells ◽  
Inflammatory Pain ◽  
Transient Receptor Potential ◽  
Sensory Nerve ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Resolvin D1 ◽  
Transient Receptor

Transient Receptor Potential Vanilloid 1 and Ankyrin 1 (TRPV1, TRPA1) cation channels are expressed in nociceptive primary sensory neurons and regulate nociceptor and inflammatory functions. Resolvins are endogenous lipid mediators. Resolvin D1 (RvD1) is described as a selective inhibitor of TRPA1-related postoperative and inflammatory pain in mice acting on the G protein-coupled receptor DRV1/GPR32. Resolvin D2 (RvD2) is a very potent TRPV1 and TRPA1 inhibitor in DRG neurons, and decreases inflammatory pain in mice acting on the GPR18 receptor, via TRPV1/TRPA1-independent mechanisms. We provided evidence that resolvins inhibited neuropeptide release from the stimulated sensory nerve terminals by TRPV1 and TRPA1 activators capsaicin (CAPS) and allyl-isothiocyanate (AITC), respectively. We showed that RvD1 and RvD2 in nanomolar concentrations significantly decreased TRPV1 and TRPA1 activation on sensory neurons by fluorescent calcium imaging and inhibited the CAPS- and AITC-evoked 45Ca-uptake on TRPV1- and TRPA1-expressing CHO cells. Since CHO cells are unlikely to express resolvin receptors, resolvins are suggested to inhibit channel opening through surrounding lipid raft disruption. Here, we proved the ability of resolvins to alter the membrane polarity related to cholesterol composition by fluorescence spectroscopy. It is concluded that targeting lipid raft integrity can open novel peripheral analgesic opportunities by decreasing the activation of nociceptors.

Effect of Nicotine on Chorda Tympani Responses to Salty and Sour Stimuli

2007 ◽  
Vol 98 (3) ◽  
pp. 1662-1674 ◽  
Author(s):  
Vijay Lyall ◽  
Tam-Hao T. Phan ◽  
Shobha Mummalaneni ◽  
Mahdis Mansouri ◽  
Gerard L. Heck ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Transient Receptor Potential ◽  
Taste Receptor ◽  
Direct Interaction ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Chorda Tympani ◽  
Sprague Dawley ◽  
Maximum Enhancement ◽  
Transient Receptor

The effect of nicotine on the benzamil (Bz)-insensitive (transient receptor potential vanilloid-1 variant cation channel, TRPV1t) and the Bz-sensitive (epithelial Na+ channel, ENaC) salt taste receptors and sour taste was investigated by monitoring intracellular Na+ and H+ activity (pHi) in polarized fungiform taste receptor cells (TRCs) and the chorda tympani (CT) nerve responses to NaCl, KCl, and HCl. CT responses in Sprague–Dawley rats and both wildtype and TRPV1 knockout (KO) mice were recorded in the presence and absence of agonists [resiniferatoxin (RTX) and elevated temperature] and an antagonist (SB-366791) of TRPV1t, the ENaC blocker (Bz), and varying apical pH (pHo). At concentrations <0.015 M, nicotine enhanced and at >0.015 M, it inhibited CT responses to KCl and NaCl. Nicotine produced maximum enhancement in the Bz-insensitive NaCl CT response at pHo between 6 and 7. RTX and elevated temperature increased the sensitivity of the CT response to nicotine in salt-containing media, and SB-366791 inhibited these effects. TRPV1 KO mice demonstrated no Bz-insensitive CT response to NaCl and no sensitivity to nicotine, RTX, and elevated temperature. We conclude that nicotine modulates salt responses by direct interaction with TRPV1t. At pHo >8, the apical membrane permeability of nicotine was increased significantly, resulting in increase in TRC pHi and volume, activation of ENaC, and enhancement of the Bz-sensitive NaCl CT response. At pHo >8, nicotine also inhibited the phasic component of the HCl CT response. We conclude that the effects of nicotine on ENaC and the phasic HCl CT response arise from increases in TRC pHi and volume.

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