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Luo HM, Ye JR, Pu FQ, Luo HL, Zhang WJ. Role and therapeutic target of P2X2/3 receptors in visceral pain. Neuropeptides 2023; 101:102355. [PMID: 37390743 DOI: 10.1016/j.npep.2023.102355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/19/2023] [Accepted: 06/21/2023] [Indexed: 07/02/2023]
Abstract
Visceral pain (VP) is caused by internal organ disease. VP is involved in nerve conduction and related signaling molecules, but its specific pathogenesis has not yet been fully elucidated. Currently, there are no effective methods for treating VP. The role of P2X2/3 in VP has progressed. After visceral organs are subjected to noxious stimulation, cells release ATP, activate P2X2/3, enhance the sensitivity of peripheral receptors and the plasticity of neurons, enhance sensory information transmission, sensitize the central nervous system, and play an important role in the development of VP. However, antagonists possess the pharmacological effect of relieving pain. Therefore, in this review, we summarize the biological functions of P2X2/3 and discuss the intrinsic link between P2X2/3 and VP. Moreover, we focus on the pharmacological effects of P2X2/3 antagonists on VP therapy and provide a theoretical basis for its targeted therapy.
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Affiliation(s)
- Hong-Mei Luo
- Department of Rheumatology, The Affiliated Hospital of Jiangxi University of Chinese Medicine, Nanchang City, Jiangxi province 343000, China
| | - Jia-Rong Ye
- Department of Gastrointestinal surgery, The Second Affiliated Hospital, Nanchang University, Nanchang City, Jiangxi province 343000, China
| | - Fan-Qin Pu
- Department of Rheumatology, The Affiliated Hospital of Jiangxi University of Chinese Medicine, Nanchang City, Jiangxi province 343000, China
| | - Hong-Liang Luo
- Department of Rehabilitation Medicine, The Second Affiliated Hospital, Nanchang University, Nanchang City, Jiangxi province 343000, China
| | - Wen-Jun Zhang
- Department of Rehabilitation Medicine, The Second Affiliated Hospital, Nanchang University, Nanchang City, Jiangxi province 343000, China.
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Qi L, Lin SH, Ma Q. Spinal VGLUT3 lineage neurons drive visceral mechanical allodynia but not sensitized visceromotor reflexes. Neuron 2023; 111:669-681.e5. [PMID: 36584681 DOI: 10.1016/j.neuron.2022.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 09/08/2022] [Accepted: 11/30/2022] [Indexed: 12/30/2022]
Abstract
Visceral pain is among the most prevalent and bothersome forms of chronic pain, but their transmission in the spinal cord is still poorly understood. Here, we conducted focal colorectal distention (fCRD) to drive both visceromotor responses (VMRs) and aversion. We first found that spinal CCK neurons were necessary for noxious fCRD to drive both VMRs and aversion under naive conditions. We next showed that spinal VGLUT3 neurons mediate visceral allodynia, whose ablation caused loss of aversion evoked by low-intensity fCRD in mice with gastrointestinal (GI) inflammation or spinal circuit disinhibition. Importantly, these neurons were dispensable for driving sensitized VMRs under both inflammatory and central disinhibition conditions. Anatomically, a subset of VGLUT3 neurons projected to parabrachial nuclei, whose photoactivation sufficiently generated aversion in mice with GI inflammation, without influencing VMRs. Our studies suggest the presence of different spinal substrates that transmit nociceptive versus affective dimensions of visceral sensory information.
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Affiliation(s)
- Lu Qi
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Shing-Hong Lin
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Qiufu Ma
- Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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Liu Y, Du J, Fang J, Xiang X, Xu Y, Wang S, Sun H, Fang J. Electroacupuncture inhibits the interaction between peripheral TRPV1 and P2X3 in rats with different pathological pain. Physiol Res 2021; 70:635-647. [PMID: 34062076 PMCID: PMC8820540 DOI: 10.33549/physiolres.934649] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/13/2021] [Indexed: 11/25/2022] Open
Abstract
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.
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Affiliation(s)
- Yingjun Liu
- Department of Neurobiology and Acupuncture Research, the Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China.
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Yu J, Du J, Fang J, Liu Y, Xiang X, Liang Y, Shao X, Fang J. The interaction between P2X3 and TRPV1 in the dorsal root ganglia of adult rats with different pathological pains. Mol Pain 2021; 17:17448069211011315. [PMID: 33906494 PMCID: PMC8108079 DOI: 10.1177/17448069211011315] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Peripheral inflammatory and neuropathic pain are closely related to the activation of purinergic receptor P2X ligand-gated ion channel 3 (P2X3) and transient receptor potential vanilloid 1 (TRPV1), but the interaction between P2X3 and TRPV1 in different types of pathological pain has rarely been reported. In this study, complete Freund’s adjuvant (CFA)-induced inflammatory pain and spared nerve injury (SNI)-induced neuropathic pain models were established in adult rats. The interactions between P2X3 and TRPV1 in the dorsal root ganglion were observed by pharmacological, co-immunoprecipitation, immunofluorescence and whole-cell patch-clamp recording assays. TRPV1 was shown to promote the induction of spontaneous pain caused by P2X3 in the SNI model, but the induction of spontaneous pain behaviour by TRPV1 was not completely dependent on P2X3 in vivo. In both the CFA and SNI models, the activation of peripheral P2X3 enhanced the effect of TRPV1 on spontaneous pain, while the inhibition of peripheral TRPV1 reduced the induction of spontaneous pain by P2X3 in the CFA model. TRPV1 and P2X3 had inhibitory effects on each other in the inflammatory pain model. During neuropathic pain, P2X3 facilitated the function of TRPV1, while TRPV1 had an inhibitory effect on P2X3. These results suggest that the mutual effects of P2X3 and TRPV1 differ in cases of inflammatory and neuropathic pain in rats.
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Affiliation(s)
- Jie Yu
- Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China.,Department of Acupuncture and Massage, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Junying Du
- Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Junfan Fang
- Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yingjun Liu
- Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Xuaner Xiang
- Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yi Liang
- Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Xiaomei Shao
- Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
| | - Jianqiao Fang
- Department of Neurobiology and Acupuncture Research, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, The Third Clinical Medical College, Zhejiang Chinese Medical University, Hangzhou, China
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Zhao Y, Siri S, Feng B, Pierce DM. Computational Modeling of Mouse Colorectum Capturing Longitudinal and Through-thickness Biomechanical Heterogeneity. J Mech Behav Biomed Mater 2021; 113:104127. [PMID: 33125950 PMCID: PMC8053306 DOI: 10.1016/j.jmbbm.2020.104127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 09/03/2020] [Accepted: 10/01/2020] [Indexed: 12/19/2022]
Abstract
Mechanotransduction, the encoding of local mechanical stresses and strains at sensory endings into neural action potentials at the viscera, plays a critical role in evoking visceral pain, e.g., in the distal colon and rectum (colorectum). The wall of the colorectum is structurally heterogeneous, including two major composites: the inner consists of muscular and submucosal layers, and the outer consists of circular muscular, intermuscular, longitudinal muscular, and serosal layers. In fact the colorectum presents biomechanical heterogenity across both the longitudinal and through-thickness directions thus highlighting the differential roles of sensory nerve endings within different regions of the colorectum in visceral mechanotransduction. We determined constitutive models and model parameters for individual layers of the colorectum from three longitudinal locations (colonic, intermediate, and distal) using nonlinear optimization to fit our experimental results from biaxial extension tests on layer-separated colorectal tissues (mouse model, 7×7 mm2, Siri et al., Am. J. Physiol. Gastrointest. Liver Physiol. 316, G473-G481 and 317, G349-G358), and quantified the thicknesses of the layers. In this study we also quantified the residual stretches stemming from separating colorectal specimens into inner and outer composites and we completed new pressure-diameter mechanical testing to provide an additional validation case. We implemented the constitutive equations and created two-layered, 3-D finite element models using FEBio (University of Utah), and incorporated the residual stretches. We validated the modeling framework by comparing FE-predicted results for both biaxial extension testing of bulk specimens of colorectum and pressure-diameter testing of bulk segments against corresponding experimental results independent of those used in our model fitting. We present the first theoretical framework to simulate the biomechanics of distal colorectum, including both longitudinal and through-thickness heterogeneity, based on constitutive modeling of biaxial extension tests of colon tissues from mice. Our constitutive models and modeling framework facilitate analyses of both fundamental questions (e.g., the impact of organ/tissue biomechanics on mechanotransduction of the sensory nerve endings, structure-function relationships, and growth and remodeling in health and disease) and specific applications (e.g., device design, minimally invasive surgery, and biomedical research).
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Affiliation(s)
- Y Zhao
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA; Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - S Siri
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - B Feng
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - D M Pierce
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA; Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA.
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Du J, Fang J, Xiang X, Yu J, Le X, Liang Y, Jin X, Fang J. Effects of low- and high-frequency electroacupuncture on protein expression and distribution of TRPV1 and P2X3 in rats with peripheral nerve injury. Acupunct Med 2020; 39:478-490. [PMID: 33334124 DOI: 10.1177/0964528420968845] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
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.
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Affiliation(s)
- Junying Du
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
| | - Junfan Fang
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
| | - Xuaner Xiang
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
| | - Jie Yu
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
| | - Xiaoqin Le
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
| | - Yi Liang
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jianqiao Fang
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou, China
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Meerschaert KA, Adelman PC, Friedman RL, Albers KM, Koerber HR, Davis BM. Unique Molecular Characteristics of Visceral Afferents Arising from Different Levels of the Neuraxis: Location of Afferent Somata Predicts Function and Stimulus Detection Modalities. J Neurosci 2020; 40:7216-7228. [PMID: 32817244 PMCID: PMC7534907 DOI: 10.1523/jneurosci.1426-20.2020] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/30/2020] [Accepted: 08/07/2020] [Indexed: 02/07/2023] Open
Abstract
Viscera receive innervation from sensory ganglia located adjacent to multiple levels of the brainstem and spinal cord. Here we examined whether molecular profiling could be used to identify functional clusters of colon afferents from thoracolumbar (TL), lumbosacral (LS), and nodose ganglia (NG) in male and female mice. Profiling of TL and LS bladder afferents was also performed. Visceral afferents were back-labeled using retrograde tracers injected into proximal and distal regions of colon or bladder, followed by single-cell qRT-PCR and analysis via an automated hierarchical clustering method. Genes were chosen for assay (32 for bladder; 48 for colon) based on their established role in stimulus detection, regulation of sensitivity/function, or neuroimmune interaction. A total of 132 colon afferents (from NG, TL, and LS ganglia) and 128 bladder afferents (from TL and LS ganglia) were analyzed. Retrograde labeling from the colon showed that NG and TL afferents innervate proximal and distal regions of the colon, whereas 98% of LS afferents only project to distal regions. There were clusters of colon and bladder afferents, defined by mRNA profiling, that localized to either TL or LS ganglia. Mixed TL/LS clustering also was found. In addition, transcriptionally, NG colon afferents were almost completely segregated from colon TL and LS neurons. Furthermore, colon and bladder afferents expressed genes at similar levels, although different gene combinations defined the clusters. These results indicate that genes implicated in both homeostatic regulation and conscious sensations are found at all anatomic levels, suggesting that afferents from different portions of the neuraxis have overlapping functions.SIGNIFICANCE STATEMENT Visceral organs are innervated by sensory neurons whose cell bodies are located in multiple ganglia associated with the brainstem and spinal cord. For the colon, this overlapping innervation is proposed to facilitate visceral sensation and homeostasis, where sensation and pain are mediated by spinal afferents and fear and anxiety (the affective aspects of visceral pain) are the domain of nodose afferents. The transcriptomic analysis performed here reveals that genes implicated in both homeostatic regulation and pain are found in afferents across all ganglia types, suggesting that conscious sensation and homeostatic regulation are the result of convergence, and not segregation, of sensory input.
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Affiliation(s)
- Kimberly A Meerschaert
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | | | - Robert L Friedman
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Kathryn M Albers
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - H Richard Koerber
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Brian M Davis
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
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Efficacy of Tenapanor in Treating Patients With Irritable Bowel Syndrome With Constipation: A 12-Week, Placebo-Controlled Phase 3 Trial (T3MPO-1). Am J Gastroenterol 2020; 115:281-293. [PMID: 31934897 PMCID: PMC7771640 DOI: 10.14309/ajg.0000000000000516] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Tenapanor is a first-in-class, minimally absorbed, small-molecule inhibitor of the gastrointestinal sodium/hydrogen exchanger isoform 3. This phase 3 trial assessed the efficacy and safety of tenapanor 50 mg b.i.d. for the treatment of patients with constipation-predominant irritable bowel syndrome (IBS-C). METHODS In this phase 3, double-blind study (ClinicalTrials.gov identifier NCT02621892), patients with IBS-C were randomized to tenapanor 50 mg b.i.d. or placebo b.i.d. for 12 weeks followed by a 4-week randomized withdrawal period. The primary efficacy variable was the proportion of patients who reported a reduction in average weekly worst abdominal pain of ≥30.0% and an increase of ≥1 complete spontaneous bowel movement from baseline, both in the same week, for ≥6 weeks of the 12-week treatment period. RESULTS Of the 629 randomized patients with IBS-C, 606 (96.3%) were included in the intention-to-treat analysis set (tenapanor: n = 307; placebo: n = 299) and 533 (84.7%) completed the 12-week treatment period. In the intention-to-treat analysis set (mean age 45 years, 81.4% women), a significantly greater proportion of patients treated with tenapanor met the primary endpoint than patients treated with placebo (27.0% vs 18.7%, P = 0.020). Abdominal symptoms and global symptoms of IBS also improved with tenapanor (P < 0.05 vs placebo). Diarrhea was the most commonly reported adverse event, resulting in study drug discontinuation in 6.5% and 0.7% of patients receiving tenapanor and placebo, respectively, during the 12-week treatment period. DISCUSSION Tenapanor 50 mg b.i.d. improved IBS-C symptoms and was generally well tolerated, offering a potential new treatment option for patients with IBS-C.
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Feng B, Guo T. Visceral pain from colon and rectum: the mechanotransduction and biomechanics. J Neural Transm (Vienna) 2019; 127:415-429. [PMID: 31598778 DOI: 10.1007/s00702-019-02088-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 09/28/2019] [Indexed: 12/14/2022]
Abstract
Visceral pain is the cardinal symptom of functional gastrointestinal (GI) disorders such as the irritable bowel syndrome (IBS) and the leading cause of patients' visit to gastroenterologists. IBS-related visceral pain usually arises from the distal colon and rectum (colorectum), an intraluminal environment that differs greatly from environment outside the body in chemical, biological, thermal, and mechanical conditions. Accordingly, visceral pain is different from cutaneous pain in several key psychophysical characteristics, which likely underlies the unsatisfactory management of visceral pain by drugs developed for other types of pain. Colorectal visceral pain is usually elicited from mechanical distension/stretch, rather than from heating, cutting, pinching, or piercing that usually evoke pain from the skin. Thus, mechanotransduction, i.e., the encoding of colorectal mechanical stimuli by sensory afferents, is crucial to the underlying mechanisms of GI-related visceral pain. This review will focus on colorectal mechanotransduction, the process of converting colorectal mechanical stimuli into trains of action potentials by the sensory afferents to inform the central nervous system (CNS). We will summarize neurophysiological studies on afferent encoding of colorectal mechanical stimuli, highlight recent advances in our understanding of colorectal biomechanics that plays critical roles in mechanotransduction, and review studies on mechano-sensitive ion channels in colorectal afferents. This review calls for focused attention on targeting colorectal mechanotransduction as a new strategy for managing visceral pain, which can also have an added benefit of limited CNS side effects, because mechanotransduction arises from peripheral organs.
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Affiliation(s)
- Bin Feng
- Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, Storrs, CT, 06269-3247, USA.
| | - Tiantian Guo
- Department of Biomedical Engineering, University of Connecticut, 260 Glenbrook Road, Unit 3247, Storrs, CT, 06269-3247, USA
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Siri S, Maier F, Santos S, Pierce DM, Feng B. Load-bearing function of the colorectal submucosa and its relevance to visceral nociception elicited by mechanical stretch. Am J Physiol Gastrointest Liver Physiol 2019; 317:G349-G358. [PMID: 31268771 PMCID: PMC6774086 DOI: 10.1152/ajpgi.00127.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mechanical distension beyond a particular threshold evokes visceral pain from distal colon and rectum (colorectum), and thus biomechanics plays a central role in visceral nociception. In this study we focused on the layered structure of the colorectum through the wall thickness and determined the biomechanical properties of layer-separated colorectal tissue. We harvested the distal 30 mm of mouse colorectum and dissected this tissue into inner and outer composite layers. The inner composite consists of the mucosa and submucosa, whereas the outer composite includes the muscular layers and serosa. We divided each composite axially into three 10-mm-long segments and conducted biaxial mechanical extension tests and opening-angle measurements for each tissue segment. In addition, we quantified the thickness of the rich collagen network in the submucosa by nonlinear imaging via second-harmonic generation (SHG). Our results reveal that the inner composite is slightly stiffer in the axial direction, whereas the outer composite is stiffer circumferentially. The stiffness of the inner composite in the axial direction is about twice that in the circumferential direction, consistent with the orientations of collagen fibers in the submucosa approximately ±30° to the axial direction. Submucosal thickness measured by SHG showed no difference from proximal to distal colorectum under the load-free condition, which likely contributes to the comparable tension stiffness of the inner composite along the colorectum. This, in turn, strongly indicates the submucosa as the load-bearing structure of the colorectum. This further implies nociceptive roles for the colorectal afferent endings in the submucosa, which likely encode tissue-injurious mechanical distension.NEW & NOTEWORTHY Visceral pain from distal colon and rectum (colorectum) is usually elicited from mechanical distension/stretch, rather than from heating, cutting, or pinching, which usually evoke pain from the skin. We conducted layer-separated biomechanical tests on mouse colorectum and identified an unexpected role of submucosa as the load-bearing structure of the colorectum. Outcomes of this study will focus attention on sensory nerve endings in the submucosa that likely encode tissue-injurious distension/stretch to cause visceral pain.
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Affiliation(s)
- Saeed Siri
- 1Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut
| | - Franz Maier
- 2Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut
| | - Stephany Santos
- 1Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut
| | - David M. Pierce
- 1Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut,2Department of Mechanical Engineering, University of Connecticut, Storrs, Connecticut
| | - Bin Feng
- 1Department of Biomedical Engineering, University of Connecticut, Storrs, Connecticut
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Abstract
The enteric nervous system of the lower gastrointestinal tract comprises intrinsic neural circuits as well as extrinsic afferent and efferent innervation. The development of strategies for neuronal gene transfer has created new opportunities for functional analysis, circuit mapping, and neuromodulation in the enteric nervous system. Studies of AAV-mediated gene transfer to enteric neurons and dorsal root ganglion neurons (DRG) have provided proofs-of-concept for the utility of AAV vectors for genetic manipulations of the intrinsic and extrinsic components of the enteric nervous system. Here we describe a method for AAV-mediated gene transfer to enteric neurons of the descending colon as well as colon-innervating DRG neurons by injection within the intestinal wall (intracolonic injection).
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Brierley SM, Hibberd TJ, Spencer NJ. Spinal Afferent Innervation of the Colon and Rectum. Front Cell Neurosci 2018; 12:467. [PMID: 30564102 PMCID: PMC6288476 DOI: 10.3389/fncel.2018.00467] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/16/2018] [Indexed: 12/12/2022] Open
Abstract
Despite their seemingly elementary roles, the colon and rectum undertake a variety of key processes to ensure our overall wellbeing. Such processes are coordinated by the transmission of sensory signals from the periphery to the central nervous system, allowing communication from the gut to the brain via the "gut-brain axis". These signals are transmitted from the peripheral terminals of extrinsic sensory nerve fibers, located within the wall of the colon or rectum, and via their axons within the spinal splanchnic and pelvic nerves to the spinal cord. Recent studies utilizing electrophysiological, anatomical and gene expression techniques indicate a surprisingly diverse set of distinct afferent subclasses, which innervate all layers of the colon and rectum. Combined these afferent sub-types allow the detection of luminal contents, low- and high-intensity stretch or contraction, in addition to the detection of inflammatory, immune, and microbial mediators. To add further complexity, the proportions of these afferents vary within splanchnic and pelvic pathways, whilst the density of the splanchnic and pelvic innervation also varies along the colon and rectum. In this review we traverse this complicated landscape to elucidate afferent function, structure, and nomenclature to provide insights into how the extrinsic sensory afferent innervation of the colon and rectum gives rise to physiological defecatory reflexes and sensations of discomfort, bloating, urgency, and pain.
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Affiliation(s)
- Stuart M Brierley
- Visceral Pain Research Group, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia.,Centre for Nutrition and Gastrointestinal Diseases, Discipline of Medicine, South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide, Adelaide, SA, Australia
| | - Timothy J Hibberd
- Visceral Neurophysiology Laboratory, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
| | - Nick J Spencer
- Visceral Neurophysiology Laboratory, Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
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13
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Grundy L, Daly DM, Chapple C, Grundy D, Chess-Williams R. TRPV1 enhances the afferent response to P2X receptor activation in the mouse urinary bladder. Sci Rep 2018; 8:197. [PMID: 29317663 PMCID: PMC5760578 DOI: 10.1038/s41598-017-18136-w] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 11/29/2017] [Indexed: 11/09/2022] Open
Abstract
Both TRPV1 and P2X receptors present on bladder sensory nerve fibres have been implicated in mechanosensation during bladder filling. The aim of this study was to determine possible interactions between these receptors in modulating afferent nerve activity. In wildtype (TRPV1+/+) and TRPV1 knockout (TRPV1-/-) mice, bladder afferent nerve activity, intravesical pressure, and luminal ATP and acetylcholine levels were determined and also intracellular calcium responses of dissociated pelvic DRG neurones and primary mouse urothelial cells (PMUCs). Bladder afferent nerve responses to the purinergic agonist αβMethylene-ATP were depressed in TRPV1-/- mice (p ≤ 0.001) and also in TRPV1+/+ mice treated with the TRPV1-antagonist capsazepine (10 µM; p ≤ 0.001). These effects were independent of changes in bladder compliance or contractility. Responses of DRG neuron to αβMethylene-ATP (30 µM) were unchanged in the TRPV1-/- mice, but the proportion of responsive neurones was reduced (p ≤ 0.01). Although the TRPV1 agonist capsaicin (1 µM) did not evoke intracellular responses in PMUCs from TRPV1+/+ mice, luminal ATP levels were reduced in the TRPV1-/- mice (p ≤ 0.001) compared to wildtype. TRPV1 modulates P2X mediated afferent responses and provides a mechanistic basis for the decrease in sensory symptoms observed following resiniferatoxin and capsaicin treatment for lower urinary tract symptoms.
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Affiliation(s)
- Luke Grundy
- Centre for Urology Research, Faculty of Health Science and Medicine, Bond University, Gold Coast, Queensland, 4229, Australia
- Visceral Pain Group, University of Adelaide, SAHMRI, Adelaide, Australia
| | - Donna M Daly
- Department of Pharmacy and Biomedical Science, University of Central Lancashire, Preston, PR1 2HE, UK
| | | | - David Grundy
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Russ Chess-Williams
- Centre for Urology Research, Faculty of Health Science and Medicine, Bond University, Gold Coast, Queensland, 4229, Australia.
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14
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Ross JL, Queme LF, Lamb JE, Green KJ, Jankowski MP. Sex differences in primary muscle afferent sensitization following ischemia and reperfusion injury. Biol Sex Differ 2018; 9:2. [PMID: 29298725 PMCID: PMC5751812 DOI: 10.1186/s13293-017-0163-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/20/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Chronic pain conditions are more prevalent in women, but most preclinical studies into mechanisms of pain generation are performed using male animals. Furthermore, whereas group III and IV nociceptive muscle afferents provoke central sensitization more effectively than their cutaneous counterparts, less is known about this critical population of muscle nociceptors. Here, we compare the physiology of individual muscle afferents in uninjured males and females. We then characterize the molecular, physiological, and behavioral effects of transient ischemia and reperfusion injury (I/R), a model we have extensively studied in males and in females. METHODS Response properties and phenotypes to mechanical, thermal, and chemical stimulation were compared using an ex vivo muscle/nerve/dorsal root ganglia (DRG)/spinal cord recording preparation. Analyses of injury-related changes were also performed by assaying evoked and spontaneous pain-related behaviors, as well as mRNA expression of the affected muscle and DRGs. The appropriate analyses of variance and post hoc tests (with false discovery rate corrections when needed) were performed for each measure. RESULTS Females have more mechanically sensitive muscle afferents and show greater mechanical and thermal responsiveness than what is found in males. With I/R, both sexes show fewer cells responsive to an innocuous metabolite solution (ATP, lactic acid, and protons), and lower mechanical thresholds in individual afferents; however, females also possess altered thermal responsiveness, which may be related to sex-dependent changes in gene expression within the affected DRGs. Regardless, both sexes show similar increases in I/R-induced pain-like behaviors. CONCLUSIONS Here, we illustrate a unique phenomenon wherein discrete, sex-dependent mechanisms of primary muscle afferent sensitization after ischemic injury to the periphery may underlie similar behavioral changes between the sexes. Furthermore, although the group III and IV muscle afferents are fully developed functionally, the differential mechanisms of sensitization manifest prior to sexual maturity. Hence, this study illustrates the pressing need for further exploration of sex differences in afferent function throughout the lifespan for use in developing appropriately targeted pain therapies.
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Affiliation(s)
- Jessica L Ross
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave MLC 6016, Cincinnati, OH, 45229, USA
| | - Luis F Queme
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave MLC 6016, Cincinnati, OH, 45229, USA
| | - Jordan E Lamb
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave MLC 6016, Cincinnati, OH, 45229, USA
| | - Kathryn J Green
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave MLC 6016, Cincinnati, OH, 45229, USA
| | - Michael P Jankowski
- Department of Anesthesia, Division of Pain Management, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave MLC 6016, Cincinnati, OH, 45229, USA. .,Department of Pediatrics, University of Cincinnati, Cincinnati, OH, 45229, USA.
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15
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He YQ, Lang XQ, Lin L, Ji L, Yuan XY, Chen Q, Ran YM, Chen HS, Li L, Wang JM, Wang ZG, Gregersen H, Zou DW, Liang HP, Yang M. P2X3 receptor-mediated visceral hyperalgesia and neuronal sensitization following exposure to PTSD-like stress in the dorsal root ganglia of rats. Neurogastroenterol Motil 2017; 29. [PMID: 27781340 DOI: 10.1111/nmo.12976] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 09/22/2016] [Indexed: 12/18/2022]
Abstract
BACKGROUND Patients with posttraumatic stress disorder (PTSD) often share co-morbidity with chronic pain conditions. Recent studies suggest a role of P2X3 receptors and ATP signaling in pain conditions. However, the underlying mechanisms of visceral hyperalgesia following exposure to PTSD-like stress conditions remain unclarified. METHODS The behavior and hormones relevant for PTSD were studied. Visceromotor responses (VMR) and the abdominal withdrawal reflexes (AWR) to colorectal distention (CRD) were recorded to determine P2X3-receptor-mediated alteration of hyperalgesia following single-prolonged stress (SPS) exposure. Immunofluorescence, Western blotting, and patch-clamp were used. KEY RESULTS The escape latency, adrenocorticotropic hormone and cortisol were increased on days 7-14. Visceromotor responses and AWR was reduced at day 1 in SPS rats but increased to higher levels than in controls after exposure to day 7. Intrathecal administration of the P2X3-receptor antagonist TNP-ATP abolished the CRD response. Based on immunofluorescence and Western blotting analysis, SPS-treated rats exhibited reduced P2X3 expression in dorsal root ganglia (DRG) after day 1 compared with controls. P2X3 expression in DRG was enhanced on day 7 after SPS and the increase of the P2X3 expression was maintained on day 14 and 21 compared with controls. The P2X3-receptor agonist α,β-me ATP (10 μM) induced a fast desensitizing inward current in DRG neurons of both control and SPS-treated rats. The average peak current densities in SPS-treated group were increased 3.6-fold. TNP-ATP (100 nM) markedly blocked all fast α,β-me ATP-induced inward currents in the DRG neurons both in control and SPS-treated rats. CONCLUSIONS & INFERENCES The data indicate an important role of P2X3 signaling in visceral hyperalgesia following PTSD-like stress.
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Affiliation(s)
- Y-Q He
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China
| | - X-Q Lang
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China
| | - L Lin
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China
| | - L Ji
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China
| | - X-Y Yuan
- Department of Gastroenterology, The Ninth People's Hospital of Chongqing, Chongqing, China
| | - Q Chen
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China
| | - Y-M Ran
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China
| | - H-S Chen
- Chongqing Key Laboratory of Translational Medical Research in Cognitive Development and Learning and Memory Disorders, Chongqing, China
| | - L Li
- Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - J-M Wang
- Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - Z-G Wang
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China.,Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - H Gregersen
- GIOME and the Key Laboratory for Biorheological Science and Technology of Ministry of Education, Bioengineering College of Chongqing University, Chongqing, China
| | - D-W Zou
- Department of Gastroenterology, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - H-P Liang
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China.,Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
| | - M Yang
- State Key Laboratory of Trauma, Burns and Combined Injury, Department of Gastroenterology, Daping Hospital, Third Military Medical University, Chongqing, China.,Research Institute of Surgery, Daping Hospital, Third Military Medical University, Chongqing, China
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16
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Abstract
Isolectin B4-binding (IB4+) dorsal root ganglion (DRG) neurons are distinct from peptidergic DRG neurons in their terminal location in the spinal cord and respective contributions to various classes and modalities of nociception. In DRG neurons innervating the mouse colon (c-DRG neurons), the reported proportion of IB4+ population is inconsistent across studies, and little is known regarding their role in colorectal mechanonociception. To address these issues, in C57BL/6J mice, we quantified IB4+ binding after labeling c-DRG neurons with Fast Blue and examined functional consequences of ablating these neurons by IB4-conjugated saporin. Sixty-one percent of Fast Blue-labeled neurons in the L6 DRG were IB4+, and 95% of these IB4+ c-DRG neurons were peptidergic. Intrathecal administration of IB4-conjugated saporin reduced the proportion of IB4+ c-DRG neurons to 37%, which was due to the loss of c-DRG neurons showing strong to medium IB4+ intensity; c-DRG neurons with weak IB4+ intensity were spared. However, this loss altered neither nociceptive behaviors to colorectal distension nor the relative proportions of stretch-sensitive colorectal afferent classes characterized by single-fiber recordings. These findings demonstrate that more than 1 half of viscerosensory L6 c-DRG neurons in C57BL/6J mouse are IB4+ and suggest, in contrast to the reported roles of IB4+/nonpeptidergic neurons in cutaneous mechanonociception, c-DRG neurons with strong-to-medium IB4+ intensity do not play a significant role in colorectal mechanonociception.
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17
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Future Targets for Female Sexual Dysfunction. J Sex Med 2016; 13:1147-65. [DOI: 10.1016/j.jsxm.2016.05.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 05/22/2016] [Accepted: 05/27/2016] [Indexed: 12/18/2022]
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18
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Enhanced binding capability of nuclear factor-κB with demethylated P2X3 receptor gene contributes to cancer pain in rats. Pain 2016; 156:1892-1905. [PMID: 26049406 PMCID: PMC4770335 DOI: 10.1097/j.pain.0000000000000248] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Supplemental Digital Content is Available in the Text. Epigenetic regulations of P2X3 receptors play a crucial role in cancer pain. Targeting p65 binding to demethylated P2X3 receptor gene suppresses cancer pain. Nuclear factor-kappa B (NF-κB) signaling is implicated in both cancer development and inflammation processes. However, the roles and mechanisms of NF-κB signaling in the development of cancer-induced pain (CIP) remain unknown. This study was designed to investigate the roles of the p65 subunit of NF-κB in regulation of the purinergic receptor (P2X3R) plasticity in dorsal root ganglion (DRG) of CIP rats. We showed here that tumor cell injection produced mechanical and thermal hyperalgesia, and an enhanced body weight–bearing difference, which was correlated with an upregulation of p65 and P2X3R expression in lumber DRGs and a potentiation of ATP-evoked responses of tibia-innervating DRG neurons. Inhibition of NF-κB signaling using p65 inhibitor pyrrolidine dithiocarbamate, BAY-11-7082, or lentiviral-p65 short-hairpin RNA significantly attenuated CIP and reversed the activities of P2X3R. Interestingly, tumor cell injection led to a significant demethylation of CpG island in p2x3r gene promoter and enhanced ability of p65 to bind the promoter of p2x3r gene. Our findings suggest that upregulation of P2X3R expression was mediated by the enhanced binding capability of p65 with demethylated promoter of p2x3r gene, thus contributing to CIP. NF-κBp65 might be a potential target for treating CIP, a neuropathic pain generated by tumor cell–induced injury to nerves that innervate the skin.
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19
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Feng B, Joyce SC, Gebhart GF. Optogenetic activation of mechanically insensitive afferents in mouse colorectum reveals chemosensitivity. Am J Physiol Gastrointest Liver Physiol 2016; 310:G790-8. [PMID: 26950857 PMCID: PMC4888546 DOI: 10.1152/ajpgi.00430.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 02/18/2016] [Indexed: 01/31/2023]
Abstract
The sensory innervation of the distal colorectum includes mechanically insensitive afferents (MIAs; ∼25%), which acquire mechanosensitivity in persistent visceral hypersensitivity and thus generate de novo input to the central nervous system. We utilized an optogenetic approach to bypass the process of transduction (generator potential) and focus on transformation (spike initiation) at colorectal MIA sensory terminals, which is otherwise not possible in typical functional studies. From channelrhodopsin2-expressing mice (driven by Advillin-Cre), the distal colorectum with attached pelvic nerve was harvested for ex vivo single-fiber recordings. Afferent receptive fields (RFs) were identified by electrical stimulation and tested for response to mechanical stimuli (probing, stroking, and stretch), and afferents were classified as either MIAs or mechanosensitive afferents (MSAs). All MIA and MSA RFs were subsequently stimulated optically and MIAs were also tested for activation/sensitization with inflammatory soup (IS), acidic hypertonic solution (AHS), and/or bile salts (BS). Responses to pulsed optical stimuli (1-10 Hz) were comparable between MSAs and MIAs whereas 43% of MIAs compared with 86% of MSAs responded tonically to stepped optical stimuli. Tonic-spiking MIAs responded preferentially to AHS (an osmotic stimulus) whereas non-tonic-spiking MIAs responded to IS (an inflammatory stimulus). A significant proportion of MIAs were also sensitized by BS. These results reveal transformation as a critical factor underlying the differences between MIAs (osmosensors vs. inflammatory sensors), revealing a previously unappreciated heterogeneity of MIA endings. The current study draws attention to the sensory encoding of MIA nerve endings that likely contribute to afferent sensitization and thus have important roles in visceral pain.
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Affiliation(s)
- Bin Feng
- Center for Pain Research, Department of Anesthesiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
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20
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Abstract
In recent years, studies have substantiated the view that P2X3 receptors play a part in the generation and transmission of purinergic signals in inflammatory and chronic neuropathic pain. Data have also been presented to suggest that the process of P2X3 receptor antagonism inhibits inflammatory hyperalgesia, involving the spinal opioid system. The aim of this study was to investigate the effect of the selective P2X3 receptor antagonist A-317491 on the development of antinociceptive tolerance to chronic morphine administration in mice. Daily systemic injection of A-317491 attenuated the morphine-induced antinociceptive tolerance to von Frey and thermal stimuli. Repeated morphine injections alone led to a significant rightward shift in the morphine dose-response curve compared with that with A-317491. A single dose of A-317491 also showed a reversal effect in morphine-tolerant mice. In a withdrawal test, co-administration of A-317491 and morphine also reduced the naloxone-induced withdrawal symptoms compared with the morphine-alone group. Thus, we propose that the P2X3 receptor is involved in the process of morphine antinociceptive tolerance and may be a new therapeutic target in the prevention of tolerance to morphine-induced antinociception.
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21
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Liu SB, Zhang MM, Cheng LF, Shi J, Lu JS, Zhuo M. Long-term upregulation of cortical glutamatergic AMPA receptors in a mouse model of chronic visceral pain. Mol Brain 2015; 8:76. [PMID: 26585043 PMCID: PMC4653882 DOI: 10.1186/s13041-015-0169-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 11/15/2015] [Indexed: 12/13/2022] Open
Abstract
Background Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders and it causes long-lasting visceral pain and discomfort. AMPA receptor mediated long-term potentiation (LTP) has been shown to play a critical role in animal models of neuropathic and inflammatory pain. No report is available for central changes in the ACC of mice with chronic visceral pain. Results In this study, we used integrative methods to investigate potential central plastic changes in the anterior cingulate cortex (ACC) of a visceral pain mouse model induced by intracolonic injection of zymosan. We found that visceral pain induced an increased expression of AMPA receptors (at the post synapses) in the ACC via an enhanced trafficking of the AMPA receptors to the membrane. Both GluA1 and GluA2/3 subunits were significantly increased. Supporting biochemical changes, excitatory synaptic transmission in the ACC were also significantly enhanced. Microinjection of AMPA receptor inhibitor IEM1460 into the ACC inhibited visceral and spontaneous pain behaviors. Furthermore, we found that the phosphorylation of GluA1 at the Ser845 site was increased, suggesting that GluA1 phosphorylation may contribute to AMPA receptor trafficking. Using genetically knockout mice lacking calcium-calmodulin stimulated adenylyl cyclase subtype 1 (AC1), we found that AMPA receptor phosphorylation and its membrane trafficking induced by zymosan injection were completely blocked. Conclusions Our results provide direct evidence for cortical AMPA receptors to contribute to zymosan-induced visceral and spontaneous pain and inhibition of AC1 activity may help to reduce chronic visceral pain.
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Affiliation(s)
- Shui-Bing Liu
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, 28 Xianning West Road, Xian, Shaanxi, 710049, China. .,Department of Pharmacology, Pharmacy of School, Fourth Military Medical University, Xian, Shaanxi, 710032, China. .,Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
| | - Ming-Ming Zhang
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, 28 Xianning West Road, Xian, Shaanxi, 710049, China. .,Department of Pharmacology, Pharmacy of School, Fourth Military Medical University, Xian, Shaanxi, 710032, China. .,Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
| | - Lin-Feng Cheng
- Department of Microbiology, Fourth Military Medical University, Xian, Shaanxi, 710032, China.
| | - Jiao Shi
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
| | - Jing-Shan Lu
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, 28 Xianning West Road, Xian, Shaanxi, 710049, China.
| | - Min Zhuo
- Center for Neuron and Disease, Frontier Institutes of Science and Technology, Xi'an Jiaotong University, 28 Xianning West Road, Xian, Shaanxi, 710049, China. .,Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada.
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22
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Greenwood-Van Meerveld B, Prusator DK, Johnson AC. Animal models of gastrointestinal and liver diseases. Animal models of visceral pain: pathophysiology, translational relevance, and challenges. Am J Physiol Gastrointest Liver Physiol 2015; 308:G885-903. [PMID: 25767262 DOI: 10.1152/ajpgi.00463.2014] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 03/11/2015] [Indexed: 02/08/2023]
Abstract
Visceral pain describes pain emanating from the thoracic, pelvic, or abdominal organs. In contrast to somatic pain, visceral pain is generally vague, poorly localized, and characterized by hypersensitivity to a stimulus such as organ distension. Animal models have played a pivotal role in our understanding of the mechanisms underlying the pathophysiology of visceral pain. This review focuses on animal models of visceral pain and their translational relevance. In addition, the challenges of using animal models to develop novel therapeutic approaches to treat visceral pain will be discussed.
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Affiliation(s)
- Beverley Greenwood-Van Meerveld
- Veterans Affairs Medical Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma; and Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Dawn K Prusator
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Anthony C Johnson
- Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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23
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Wieskopf JS, Mathur J, Limapichat W, Post MR, Al-Qazzaz M, Sorge RE, Martin LJ, Zaykin DV, Smith SB, Freitas K, Austin JS, Dai F, Zhang J, Marcovitz J, Tuttle AH, Slepian PM, Clarke S, Drenan RM, Janes J, Al Sharari S, Segall SK, Aasvang EK, Lai W, Bittner R, Richards CI, Slade GD, Kehlet H, Walker J, Maskos U, Changeux JP, Devor M, Maixner W, Diatchenko L, Belfer I, Dougherty DA, Su AI, Lummis SCR, Imad Damaj M, Lester HA, Patapoutian A, Mogil JS. The nicotinic α6 subunit gene determines variability in chronic pain sensitivity via cross-inhibition of P2X2/3 receptors. Sci Transl Med 2015; 7:287ra72. [PMID: 25972004 PMCID: PMC5018401 DOI: 10.1126/scitranslmed.3009986] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Chronic pain is a highly prevalent and poorly managed human health problem. We used microarray-based expression genomics in 25 inbred mouse strains to identify dorsal root ganglion (DRG)-expressed genetic contributors to mechanical allodynia, a prominent symptom of chronic pain. We identified expression levels of Chrna6, which encodes the α6 subunit of the nicotinic acetylcholine receptor (nAChR), as highly associated with allodynia. We confirmed the importance of α6* (α6-containing) nAChRs by analyzing both gain- and loss-of-function mutants. We find that mechanical allodynia associated with neuropathic and inflammatory injuries is significantly altered in α6* mutants, and that α6* but not α4* nicotinic receptors are absolutely required for peripheral and/or spinal nicotine analgesia. Furthermore, we show that Chrna6's role in analgesia is at least partially due to direct interaction and cross-inhibition of α6* nAChRs with P2X2/3 receptors in DRG nociceptors. Finally, we establish the relevance of our results to humans by the observation of genetic association in patients suffering from chronic postsurgical and temporomandibular pain.
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Affiliation(s)
- Jeffrey S Wieskopf
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Jayanti Mathur
- Genomic Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Walrati Limapichat
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Michael R Post
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mona Al-Qazzaz
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - Robert E Sorge
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Loren J Martin
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Dmitri V Zaykin
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
| | - Shad B Smith
- Center for Neurosensory Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Kelen Freitas
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23219, USA
| | - Jean-Sebastien Austin
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Feng Dai
- Departments of Anesthesiology and Human Genetics, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jie Zhang
- Genomic Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Jaclyn Marcovitz
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Alexander H Tuttle
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Peter M Slepian
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Sarah Clarke
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada
| | - Ryan M Drenan
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
| | - Jeff Janes
- Genomic Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Shakir Al Sharari
- Department of Pharmacology, King Saud University, P. O. Box 2457, Riyadh 11451, Saudi Arabia
| | - Samantha K Segall
- Center for Neurosensory Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Eske K Aasvang
- Section for Surgical Pathophysiology, Rigshospitalet, Copenhagen University, 2100 Copenhagen, Denmark
| | - Weike Lai
- Departments of Anesthesiology and Human Genetics, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Reinhard Bittner
- Department of Surgery, Marienhospital Stuttgart, 70199 Stuttgart, Germany
| | | | - Gary D Slade
- Department of Dental Ecology, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Henrik Kehlet
- Section for Surgical Pathophysiology, Rigshospitalet, Copenhagen University, 2100 Copenhagen, Denmark
| | - John Walker
- Genomic Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
| | - Uwe Maskos
- Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571, Département de Neuroscience, Institute Pasteur, 75724 Paris, France
| | - Jean-Pierre Changeux
- Neurobiologie Intégrative des Systèmes Cholinergiques, CNRS UMR 3571, Département de Neuroscience, Institute Pasteur, 75724 Paris, France
| | - Marshall Devor
- Department of Cell and Developmental Biology, Institute of Life Sciences and Center for Research on Pain, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - William Maixner
- Center for Neurosensory Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Luda Diatchenko
- Center for Neurosensory Disorders, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Faculty of Dentistry, Department of Anesthesia, and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1G1, Canada
| | - Inna Belfer
- Departments of Anesthesiology and Human Genetics, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Andrew I Su
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sarah C R Lummis
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23219, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ardem Patapoutian
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, and Howard Hughes Medical Institute, La Jolla, CA 92037, USA
| | - Jeffrey S Mogil
- Department of Psychology and Alan Edwards Centre for Research on Pain, McGill University, Montreal, Quebec H3A 1B1, Canada.
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24
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Feng B, Zhu Y, La JH, Wills ZP, Gebhart GF. Experimental and computational evidence for an essential role of NaV1.6 in spike initiation at stretch-sensitive colorectal afferent endings. J Neurophysiol 2015; 113:2618-34. [PMID: 25652923 DOI: 10.1152/jn.00717.2014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 02/03/2015] [Indexed: 12/15/2022] Open
Abstract
Stretch-sensitive afferents comprise ∼33% of the pelvic nerve innervation of mouse colorectum, which are activated by colorectal distension and encode visceral nociception. Stretch-sensitive colorectal afferent endings respond tonically to stepped or ramped colorectal stretch, whereas dissociated colorectal dorsal root ganglion neurons generally fail to spike repetitively upon stepped current stimulation. The present study investigated this difference in the neural encoding characteristics between the soma and afferent ending using pharmacological approaches in an in vitro mouse colon-nerve preparation and complementary computational simulations. Immunohistological staining and Western blots revealed the presence of voltage-gated sodium channel (NaV) 1.6 and NaV1.7 at sensory neuronal endings in mouse colorectal tissue. Responses of stretch-sensitive colorectal afferent endings were significantly reduced by targeting NaV1.6 using selective antagonists (μ-conotoxin GIIIa and μ-conotoxin PIIIa) or tetrodotoxin. In contrast, neither selective NaV1.8 (A803467) nor NaV1.7 (ProTX-II) antagonists attenuated afferent responses to stretch. Computational simulation of a colorectal afferent ending that incorporated independent Markov models for NaV1.6 and NaV1.7, respectively, recapitulated the experimental findings, suggesting a necessary role for NaV1.6 in encoding tonic spiking by stretch-sensitive afferents. In addition, computational simulation of a dorsal root ganglion soma showed that, by adding a NaV1.6 conductance, a single-spiking neuron was converted into a tonic spiking one. These results suggest a mechanism/channel to explain the difference in neural encoding characteristics between afferent somata and sensory endings, likely caused by differential expression of ion channels (e.g., NaV1.6) at different parts of the neuron.
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Affiliation(s)
- Bin Feng
- Department of Anesthesiology, Center for Pain Research, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Yi Zhu
- Department of Anesthesiology, Center for Pain Research, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Jun-Ho La
- Department of Anesthesiology, Center for Pain Research, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Zachary P Wills
- Department of Neurobiology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - G F Gebhart
- Department of Anesthesiology, Center for Pain Research, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; and
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25
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Feng B, Gebhart GF. In vitro functional characterization of mouse colorectal afferent endings. J Vis Exp 2015:52310. [PMID: 25651300 DOI: 10.3791/52310] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
This video demonstrates in detail an in vitro single-fiber electrophysiological recording protocol using a mouse colorectum-nerve preparation. The approach allows unbiased identification and functional characterization of individual colorectal afferents. Extracellular recordings of propagated action potentials (APs) that originate from one or a few afferent (i.e., single-fiber) receptive fields (RFs) in the colorectum are made from teased nerve fiber fascicles. The colorectum is removed with either the pelvic (PN) or lumbar splanchnic (LSN) nerve attached and opened longitudinally. The tissue is placed in a recording chamber, pinned flat and perfused with oxygenated Krebs solution. Focal electrical stimulation is used to locate the colorectal afferent endings, which are further tested by three distinct mechanical stimuli (blunt probing, mucosal stroking and circumferential stretch) to functionally categorize the afferents into five mechanosensitive classes. Endings responding to none of these mechanical stimuli are categorized as mechanically-insensitive afferents (MIAs). Both mechanosensitive and MIAs can be assessed for sensitization (i.e., enhanced response, reduced threshold, and/or acquisition of mechanosensitivity) by localized exposure of RFs to chemicals (e.g., inflammatory soup (IS), capsaicin, adenosine triphosphate (ATP)). We describe the equipment and colorectum-nerve recording preparation, harvest of colorectum with attached PN or LSN, identification of RFs in the colorectum, single-fiber recording from nerve fascicles, and localized application of chemicals to the RF. In addition, challenges of the preparation and application of standardized mechanical stimulation are also discussed.
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Affiliation(s)
- Bin Feng
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh;
| | - G F Gebhart
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh
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26
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Hulse RP, Beazley-Long N, Hua J, Kennedy H, Prager J, Bevan H, Qiu Y, Fernandes ES, Gammons MV, Ballmer-Hofer K, Gittenberger de Groot AC, Churchill AJ, Harper SJ, Brain SD, Bates DO, Donaldson LF. Regulation of alternative VEGF-A mRNA splicing is a therapeutic target for analgesia. Neurobiol Dis 2014; 71:245-59. [PMID: 25151644 PMCID: PMC4194316 DOI: 10.1016/j.nbd.2014.08.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/29/2014] [Accepted: 08/06/2014] [Indexed: 12/02/2022] Open
Abstract
Vascular endothelial growth factor-A (VEGF-A) is best known as a key regulator of the formation of new blood vessels. Neutralization of VEGF-A with anti-VEGF therapy e.g. bevacizumab, can be painful, and this is hypothesized to result from a loss of VEGF-A-mediated neuroprotection. The multiple vegf-a gene products consist of two alternatively spliced families, typified by VEGF-A165a and VEGF-A165b (both contain 165 amino acids), both of which are neuroprotective. Under pathological conditions, such as in inflammation and cancer, the pro-angiogenic VEGF-A165a is upregulated and predominates over the VEGF-A165b isoform. We show here that in rats and mice VEGF-A165a and VEGF-A165b have opposing effects on pain, and that blocking the proximal splicing event – leading to the preferential expression of VEGF-A165b over VEGF165a – prevents pain in vivo. VEGF-A165a sensitizes peripheral nociceptive neurons through actions on VEGFR2 and a TRPV1-dependent mechanism, thus enhancing nociceptive signaling. VEGF-A165b blocks the effect of VEGF-A165a. After nerve injury, the endogenous balance of VEGF-A isoforms switches to greater expression of VEGF-Axxxa compared to VEGF-Axxxb, through an SRPK1-dependent pre-mRNA splicing mechanism. Pharmacological inhibition of SRPK1 after traumatic nerve injury selectively reduced VEGF-Axxxa expression and reversed associated neuropathic pain. Exogenous VEGF-A165b also ameliorated neuropathic pain. We conclude that the relative levels of alternatively spliced VEGF-A isoforms are critical for pain modulation under both normal conditions and in sensory neuropathy. Altering VEGF-Axxxa/VEGF-Axxxb balance by targeting alternative RNA splicing may be a new analgesic strategy. The different vegf-a splice variants, VEGF-A165a and VEGF-A165b have pro- and anti-nociceptive actions respectively. Pro-nociceptive actions of VEGF-A165a are dependent on TRPV1. Alternative pre-mRNA splicing underpins peripheral sensitization by VEGF-A isoforms in normal and neuropathic animals.
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Affiliation(s)
- R P Hulse
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK; Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham NG2 7UH, UK
| | - N Beazley-Long
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK; School of Life Sciences, The Medical School, University of Nottingham, Queen's Medical Centre, Nottingham NG2 7UH, UK
| | - J Hua
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | - H Kennedy
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | - J Prager
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | - H Bevan
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | - Y Qiu
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | | | - M V Gammons
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | | | | | - A J Churchill
- Clinical Sciences, University of Bristol, Bristol BS1 2LX, UK
| | - S J Harper
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | - S D Brain
- King's College London, London SE1 9NH, UK
| | - D O Bates
- Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham NG2 7UH, UK.
| | - L F Donaldson
- Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK; School of Life Sciences, The Medical School, University of Nottingham, Queen's Medical Centre, Nottingham NG2 7UH, UK.
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27
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Abstract
TRPV1 is a well-characterised channel expressed by a subset of peripheral sensory neurons involved in pain sensation and also at a number of other neuronal and non-neuronal sites in the mammalian body. Functionally, TRPV1 acts as a sensor for noxious heat (greater than ~42 °C). It can also be activated by some endogenous lipid-derived molecules, acidic solutions (pH < 6.5) and some pungent chemicals and food ingredients such as capsaicin, as well as by toxins such as resiniferatoxin and vanillotoxins. Structurally, TRPV1 subunits have six transmembrane (TM) domains with intracellular N- (containing 6 ankyrin-like repeats) and C-termini and a pore region between TM5 and TM6 containing sites that are important for channel activation and ion selectivity. The N- and C- termini have residues and regions that are sites for phosphorylation/dephosphorylation and PI(4,5)P2 binding, which regulate TRPV1 sensitivity and membrane insertion. The channel has several interacting proteins, some of which (e.g. AKAP79/150) are important for TRPV1 phosphorylation. Four TRPV1 subunits form a non-selective, outwardly rectifying ion channel permeable to monovalent and divalent cations with a single-channel conductance of 50-100 pS. TRPV1 channel kinetics reveal multiple open and closed states, and several models for channel activation by voltage, ligand binding and temperature have been proposed. Studies with TRPV1 agonists and antagonists and Trpv1 (-/-) mice have suggested a role for TRPV1 in pain, thermoregulation and osmoregulation, as well as in cough and overactive bladder. TRPV1 antagonists have advanced to clinical trials where findings of drug-induced hyperthermia and loss of heat sensitivity have raised questions about the viability of this therapeutic approach.
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28
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Hockley JRF, Boundouki G, Cibert-Goton V, McGuire C, Yip PK, Chan C, Tranter M, Wood JN, Nassar MA, Blackshaw LA, Aziz Q, Michael GJ, Baker MD, Winchester WJ, Knowles CH, Bulmer DC. Multiple roles for NaV1.9 in the activation of visceral afferents by noxious inflammatory, mechanical, and human disease-derived stimuli. Pain 2014; 155:1962-75. [PMID: 24972070 PMCID: PMC4220011 DOI: 10.1016/j.pain.2014.06.015] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Revised: 05/28/2014] [Accepted: 06/19/2014] [Indexed: 01/17/2023]
Abstract
Chronic visceral pain affects millions of individuals worldwide and remains poorly understood, with current therapeutic options constrained by gastrointestinal adverse effects. Visceral pain is strongly associated with inflammation and distension of the gut. Here we report that the voltage-gated sodium channel subtype NaV1.9 is expressed in half of gut-projecting rodent dorsal root ganglia sensory neurons. We show that NaV1.9 is required for normal mechanosensation, for direct excitation and for sensitization of mouse colonic afferents by mediators from inflammatory bowel disease tissues, and by noxious inflammatory mediators individually. Excitatory responses to ATP or PGE2 were substantially reduced in NaV1.9(-/-) mice. Deletion of NaV1.9 substantially attenuates excitation and subsequent mechanical hypersensitivity after application of inflammatory soup (IS) (bradykinin, ATP, histamine, PGE2, and 5HT) to visceral nociceptors located in the serosa and mesentery. Responses to mechanical stimulation of mesenteric afferents were also reduced by loss of NaV1.9, and there was a rightward shift in stimulus-response function to ramp colonic distension. By contrast, responses to rapid, high-intensity phasic distension of the colon are initially unaffected; however, run-down of responses to repeat phasic distension were exacerbated in NaV1.9(-/-) afferents. Finally colonic afferent activation by supernatants derived from inflamed human tissue was greatly reduced in NaV1.9(-/-) mice. These results demonstrate that NaV1.9 is required for persistence of responses to intense mechanical stimulation, contributes to inflammatory mechanical hypersensitivity, and is essential for activation by noxious inflammatory mediators, including those from diseased human bowel. These observations indicate that NaV1.9 represents a high-value target for development of visceral analgesics.
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Affiliation(s)
- James R F Hockley
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AJ, UK; National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - George Boundouki
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AJ, UK; National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Vincent Cibert-Goton
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Cian McGuire
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Ping K Yip
- Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Christopher Chan
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Michael Tranter
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - John N Wood
- Molecular Nociception Group, Wolfson Institute for Biomedical Research, University College London, London WC1E 6BT, UK
| | - Mohammed A Nassar
- Department of Biomedical Science, The University of Sheffield, Sheffield S10 2TN, UK
| | - L Ashley Blackshaw
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AJ, UK; National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Qasim Aziz
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AJ, UK
| | - Gregory J Michael
- Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Mark D Baker
- Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Wendy J Winchester
- Neusentis (Pfizer Ltd), The Portway Building, Granta Science Park, Cambridge CB21 6GS, UK
| | - Charles H Knowles
- National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - David C Bulmer
- Wingate Institute of Neurogastroenterology, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AJ, UK; National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK.
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