RESUMO
Chronic visceral pain, altered motility and bladder dysfunction are common, yet poorly managed symptoms of functional and inflammatory disorders of the gastrointestinal and urinary tracts. Recently, numerous human channelopathies of the voltage-gated sodium (NaV ) channel family have been identified, which induce either painful neuropathies, an insensitivity to pain, or alterations in smooth muscle function. The identification of these disorders, in addition to the recent utilisation of genetically modified NaV mice and specific NaV channel modulators, has shed new light on how NaV channels contribute to the function of neuronal and non-neuronal tissues within the gastrointestinal tract and bladder. Here we review the current pre-clinical and clinical evidence to reveal how the nine NaV channel family members (NaV 1.1-NaV 1.9) contribute to abdominal visceral function in normal and disease states.
Assuntos
Nociceptividade , Dor Nociceptiva/fisiopatologia , Células Receptoras Sensoriais/patologia , Vísceras/patologia , Canais de Sódio Disparados por Voltagem/metabolismo , Animais , HumanosRESUMO
α-Conotoxins are disulfide-rich peptides that target nicotinic acetylcholine receptors. Recently we identified several α-conotoxins that also modulate voltage-gated calcium channels by acting as G protein-coupled GABA(B) receptor (GABA(B)R) agonists. These α-conotoxins are promising drug leads for the treatment of chronic pain. To elucidate the diversity of α-conotoxins that act through this mechanism, we synthesized and characterized a set of peptides with homology to α-conotoxins known to inhibit high voltage-activated calcium channels via GABA(B)R activation. Remarkably, all disulfide isomers of the active α-conotoxins Pu1.2 and Pn1.2, and the previously studied Vc1.1 showed similar levels of biological activity. Structure determination by NMR spectroscopy helped us identify a simplified biologically active eight residue peptide motif containing a single disulfide bond that is an excellent lead molecule for developing a new generation of analgesic peptide drugs.
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Motivos de Aminoácidos , Bloqueadores dos Canais de Cálcio/farmacologia , Conotoxinas/química , Cisteína/análise , Receptores de GABA-B/metabolismo , Sequência de Aminoácidos , Animais , Conotoxinas/farmacologia , Humanos , Receptores de GABA-B/química , Homologia de Sequência de Aminoácidos , Relação Estrutura-Atividade , XenopusRESUMO
OBJECTIVES: Substantial evidence implicates mast cells and their main constituent histamine in the pathogenesis of visceral hypersensitivity. We explored the specific contribution of histamine H4 (H4R) and H1 (H1R) receptors to visceral hypersensitivity in a postinflammatory rat model. DESIGN: Trinitrobenzenesulfonic acid (TNBS)-colitis was monitored individually by colonoscopy: first on day 3 to confirm the presence of colitis and then every 4â days, starting from day 10, to monitor convalescence and determine the exact timepoint of endoscopic healing in each rat. Experiments were performed 3â days after endoscopic resolution of colitis. Visceral sensitivity was assessed by quantifying visceromotor responses (VMRs) to colorectal distension. Colonic mast cell numbers, histamine release and H4R and H1R mRNA expression were quantified. JNJ7777120 (H4R antagonist) and/or levocetirizine (H1R antagonist) were administered 30â min prior to VMR assessment or histamine release assay. RESULTS: Postcolitis rats displayed a higher number of colonic mast cells, excessive histamine release and significantly enhanced VMRs. Heightened VMRs were dose-dependently reduced by JNJ7777120 and levocetirizine; combined administration of JNJ7777120 and levocetirizine potentiated the antinociceptive effect. In the colon, both H4R and H1R mRNA were present; in the dorsal root ganglia, only H1R mRNA was found. Only colonic H4R mRNA expression was increased in postcolitis rats. Excessive histamine release in postcolitis rats was attenuated by the highest dose of JNJ7777120. CONCLUSIONS: H4R and H1R antagonists dose-dependently reduce and even normalise postinflammatory visceral hypersensitivity via different underlying mechanisms but with a synergistic effect. Both receptor subtypes represent promising targets for the treatment of postinflammatory visceral hypersensitivity.
Assuntos
Colite , Hipersensibilidade , Mucosa Intestinal , Receptores Acoplados a Proteínas G , Receptores Histamínicos H1/metabolismo , Receptores Histamínicos , Regeneração , Animais , Cetirizina/farmacologia , Colite/complicações , Colite/diagnóstico , Colite/etiologia , Colite/metabolismo , Colite/fisiopatologia , Colonoscopia/métodos , Convalescença , Modelos Animais de Doenças , Histamina/metabolismo , Antagonistas não Sedativos dos Receptores H1 da Histamina/farmacologia , Liberação de Histamina/fisiologia , Hipersensibilidade/etiologia , Hipersensibilidade/metabolismo , Hipersensibilidade/fisiopatologia , Hipersensibilidade/terapia , Indóis/farmacologia , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patologia , Masculino , Mastócitos/efeitos dos fármacos , Mastócitos/metabolismo , Piperazinas/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores Acoplados a Proteínas G/metabolismo , Receptores Histamínicos/metabolismo , Receptores Histamínicos H4 , Regeneração/efeitos dos fármacos , Regeneração/fisiologia , Ácido Trinitrobenzenossulfônico/farmacologiaRESUMO
In this study, we evaluated the partial volume effect (PVE) of 2-deoxy-2-[18F]fluoro-d-glucose (18F-FDG) tracer accumulation in the bladder on the positron emission tomographic (PET) image quantification in mice and rats suffering from inflammatory bowel disease. To improve the accuracy, we implemented continuous bladder flushing procedures. Female mice and rats were scanned using microPET/computed tomography (CT) at baseline and after induction of acute colitis by injecting 2,4,6-trinitrobenzene sulfonic acid (TNBS) intrarectally. During the scans, the bladder was continuously flushed in one group, whereas in the other group, no bladder flushing was performed. As a means of in vivo and ex vivo validation of the inflammation, animals also underwent colonoscopy and were sacrificed for gamma counting (subpopulation) and to score the colonic damage both micro- and macroscopically as well as biochemically. At baseline, the microPET signal in the colon of both mice and rats was significantly higher in the nonflushed group compared to the flushed group, caused by the PVE of tracer activity in the bladder. Hence, the colonoscopy and postmortem analyses showed no significant differences at baseline between the flushed and nonflushed animals. TNBS induced significant colonic inflammation, as revealed by colonoscopic and postmortem scores, which was not detected by microPET in the mice without bladder flushing, again because of spillover of bladder activity in the colonic area. MicroPET in bladder-flushed animals did reveal a significant increase in 18F-FDG uptake. Correlations between microPET and colonoscopy, macroscopy, microscopy, and myeloperoxidase yielded higher Spearman rho values in mice with continuously flushed bladders during imaging. Comparable, although somewhat less pronounced, results were shown in the rat. Continuous bladder flushing reduced image artifacts and is mandatory for accurate image quantification in the pelvic region for both mice and rats. We designed and validated experimental protocols to facilitate such.
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Colite/diagnóstico por imagem , Colite/diagnóstico , Fluordesoxiglucose F18 , Imagem Molecular/métodos , Compostos Radiofarmacêuticos , Bexiga Urinária/diagnóstico por imagem , Animais , Colite/induzido quimicamente , Colite/patologia , Colonoscopia , Feminino , Processamento de Imagem Assistida por Computador , Camundongos , Tomografia por Emissão de Pósitrons , Ratos , Tomografia Computadorizada por Raios X , Ácido Trinitrobenzenossulfônico , Bexiga Urinária/patologiaRESUMO
Visceral sensitivity is of pathophysiological importance in abdominal pain disorders and can be modulated by inflammation and stress. However, it is unclear whether inflammation and stress alter visceral perception independently of each other or in conjunction through neuroendocrine interactions. Therefore, we compared the short- and long-term effects of experimental colitis and water avoidance stress (WAS), alone or in combination, on visceral sensitivity in female Wistar rats. Colitis was induced by trinitrobenzene sulfonic acid (TNBS) and colonoscopically confirmed. During WAS, rats were placed on a platform surrounded by water for 1 h. Visceral sensitivity was assessed by quantifying the visceromotor responses (VMRs) to colorectal distension. Activation of the hypothalamic-pituitary-adrenal axis was determined by measuring serum corticosterone in a separate protocol. TNBS instillation resulted in overt colitis, associated with significant visceral hypersensitivity during the acute inflammatory phase (3 days post-TNBS; n = 8/group); after colitis had subsided (28 days post-TNBS), hypersensitivity was resolved (n = 4-8/group). Single WAS was associated with increased VMRs of a magnitude comparable to acute TNBS-induced hypersensitivity (n = 8/group). However, after repetitive WAS no significant hypersensitivity was present (n = 8/group). No additive effect of colitis and stress was seen on visceral pain perception (n = 6-8/group). Corticosterone levels were only increased in acute TNBS-colitis, acute WAS and their combination. To conclude, both colitis and stress successfully induced short-term visceral hypersensitivity and activated the hypothalamic-pituitary-adrenal axis, but long-term effects were absent. In addition, our current findings do not support an additive effect of colitis and stress on visceral sensitivity in female Wistar rats.
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Colite/fisiopatologia , Hiperalgesia/fisiopatologia , Estresse Psicológico/fisiopatologia , Dor Visceral/fisiopatologia , Animais , Colite/psicologia , Feminino , Hiperalgesia/psicologia , Ratos , Ratos Wistar , Estresse Psicológico/psicologia , Ácido Trinitrobenzenossulfônico/toxicidade , Dor Visceral/psicologiaRESUMO
Janus kinase (JAK) signaling has been implicated in human inflammatory diseases, including psoriasis, rheumatoid arthritis, and inflammatory bowel disease. Lorpucitinib (JNJ-64251330) is an oral, small molecule, pan-JAK inhibitor. Unlike systemic JAK antagonists, lorpucitinib was found to have enteric (gut)-selective properties, providing possible applications in diseases of the human gastrointestinal tract. Here, lorpucitinib was evaluated in a phase I, two-part, dosing study (NCT04552197) to assess pharmacokinetics, pharmacodynamic biomarkers, and safety in healthy participants. In part 1, 24 participants were randomized to 1 of 4 treatment arms receiving either lorpucitinib (30 mg daily, 30 mg every 12 hours (q12h), or 75 mg q12h) or tofacitinib (5 mg q12h) for 5 days. Part 2 was a food-effect study in which 12 participants received a single 75-mg dose of lorpucitinib under either fasting or fed conditions. In part 1, plasma and gut tissue concentrations of lorpucitinib showed approximately dose-proportional increases. At all doses, lorpucitinib concentrations were significantly higher (392- to 1928-fold) in the gut mucosal biopsies vs. the corresponding plasma samples, demonstrating high enteric selectivity and significantly exceeding both the tissue concentrations (> 200-fold) and tissue/plasma ratios observed with tofacitinib. JAK inhibition in biopsies was confirmed via reduction in pSTAT-3 levels. In part 2, lorpucitinib plasma concentrations were detectable but at low levels, with no statistical differences in PK parameters between the fed and fasted groups. Lorpucitinib was safe and well-tolerated, and the data may be useful in designing studies to evaluate lorpucitinib in patients with JAK/STAT-driven gastrointestinal diseases.
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Artrite Reumatoide , Doenças Inflamatórias Intestinais , Inibidores de Janus Quinases , Humanos , Inibidores de Janus Quinases/efeitos adversos , Voluntários Saudáveis , Artrite Reumatoide/tratamento farmacológico , Jejum , Doenças Inflamatórias Intestinais/tratamento farmacológicoRESUMO
Lunsekimig is a novel, bispecific NANOBODY® molecule that inhibits both thymic stromal lymphopoietin (TSLP) and interleukin (IL)-13, two key mediators of asthma pathophysiology. In this first-in-human study, we evaluated the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of lunsekimig in healthy adult participants. Participants received single ascending doses (SAD) of lunsekimig (10-400 mg intravenous [IV] or 400 mg subcutaneous [SC]) (SAD part) or multiple ascending doses (MAD part) of lunsekimig (100 or 200 mg, every 2 weeks [Q2W] for three SC doses), or placebo. Overall, 48 participants were randomized 3:1 in the SAD part and 4:1 in the MAD part for lunsekimig or placebo. The primary endpoint was safety and tolerability. The secondary endpoints included PK, antidrug antibodies (ADAs) and total target measurement. Lunsekimig was well tolerated and common treatment-emergent adverse events were COVID-19, nasopharyngitis, injection site reactions, and headache. Lunsekimig showed dose-proportional increases in exposure and linear elimination. Mean t1/2z of lunsekimig was around 10 days across all IV and SC doses of the SAD and MAD parts of the study. Increases in the serum concentration of total TSLP and IL-13 for lunsekimig versus placebo indicated target engagement. ADA of low titers were detected in four (11.1%) participants who received lunsekimig in the SAD, and seven (43.8%) in the MAD. In conclusion, lunsekimig was well tolerated in healthy participants with a linear PK profile up to single 400 mg IV and SC dose and multiple doses of 100 and 200 mg SC Q2W, with low immunogenicity.
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Citocinas , Voluntários Saudáveis , Interleucina-13 , Anticorpos de Domínio Único , Linfopoietina do Estroma do Timo , Humanos , Adulto , Masculino , Feminino , Interleucina-13/antagonistas & inibidores , Interleucina-13/imunologia , Anticorpos de Domínio Único/administração & dosagem , Anticorpos de Domínio Único/imunologia , Anticorpos de Domínio Único/efeitos adversos , Pessoa de Meia-Idade , Citocinas/imunologia , Citocinas/sangue , Adulto Jovem , Injeções Subcutâneas , Método Duplo-Cego , Relação Dose-Resposta a Droga , Esquema de MedicaçãoRESUMO
Remote inflammation monitoring with digital health technologies (DHTs) would provide valuable information for both clinical research and care. Controlled perturbations of the immune system may reveal physiological signatures which could be used to develop a digital biomarker of inflammatory state. In this study, molecular and physiological profiling was performed following an in vivo lipopolysaccharide (LPS) challenge to develop a digital biomarker of inflammation. Ten healthy volunteers received an intravenous LPS challenge and were monitored for 24 h using the VitalConnect VitalPatch (VitalPatch). VitalPatch measurements included heart rate (HR), heart rate variability (HRV), respiratory rate (RR), and skin temperature (TEMP). Conventional episodic inpatient vital signs and serum proteins were measured pre- and post-LPS challenge. The VitalPatch provided vital signs that were comparable to conventional methods for assessing HR, RR, and TEMP. A pronounced increase was observed in HR, RR, and TEMP as well as a decrease in HRV 1-4 h post-LPS challenge. The ordering of participants by magnitude of inflammatory cytokine response 2 h post-LPS challenge was consistent with ordering of participants by change from baseline in vital signs when measured by VitalPatch (r = 0.73) but not when measured by conventional methods (r = -0.04). A machine learning model trained on VitalPatch data predicted change from baseline in inflammatory protein response (R2 = 0.67). DHTs, such as VitalPatch, can improve upon existing episodic measurements of vital signs by enabling continuous sensing and have the potential for future use as tools to remotely monitor inflammation.
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Lipopolissacarídeos , Dispositivos Eletrônicos Vestíveis , Humanos , Sinais Vitais , Inflamação/diagnóstico , BiomarcadoresRESUMO
Protocols for clinical trials describe inclusion and exclusion criteria based on general and compound-specific considerations to ensure subject safety and data quality. In phase I clinical trials, healthy volunteers (HVs) are screened against these criteria that often specify predefined eligibility ranges for vital signs, electrocardiogram, and laboratory tests. HVs are excluded if baseline parameters deviate from these ranges even though this may not indicate underlying pathology, which could delay trial execution. Data from 3365 HVs participating in 9670 screening visits for 94 phase I HV trials, conducted between December 2008 and May 2019 at the Janssen Clinical Pharmacology Unit, were retrospectively analyzed. Commonly predefined protocol ranges were overlaid with HV data to estimate predicted screen failure rates (SFRs). Of the overall population, 91% was White and 64% were men with mean age of 42.8 ± 12.5 years. High predicted SFRs are related to cardiovascular/metabolic (body mass index, heart rate [HR], blood pressure [BP], and corrected QT Fridericia's formula [QTcF]), renal (estimated glomerular filtration rate [eGFR]), liver (alanine aminotransferase [ALT], and total bilirubin), and coagulation (prothrombin time [PT]) parameters. Predicted SFRs increased with age for high systolic and diastolic BP, QTcF interval, and eGFR. In contrast, lower SFRs in the older age groups were seen for low diastolic BP, liver function test, ALT, PT, and total bilirubin. This analysis can be used to inform on study design, protocol inclusion and exclusion criteria, and to optimize the screening process. Data-driven critical appraisal of proposed inclusion and exclusion criteria using a risk-based approach may significantly reduce screen failure rates without compromising subjects' safety.
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Voluntários Saudáveis , Programas de Rastreamento , Seleção de Pacientes , Projetos de Pesquisa , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Programas de Rastreamento/normas , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto JovemRESUMO
BACKGROUND: Postprandial symptoms in irritable bowel syndrome (IBS) have been associated with increased bowel contractility. AIM: To compare ileocolonic and colonic responses to feeding in health and IBS. METHODS: We prospectively analyzed data from separate research trials in 122 IBS patients and 41 healthy volunteers. Ileocolonic transit (ICT) was evaluated before (colonic filling [CF]3h) and immediately after (CF4 h) a standard lunch at 3 h 45 min, and 2 h thereafter. The colonic geometric center (GC) was calculated 2 h (GC6 h) after lunch ingested at 4 h (GC4 h) and directly after (GC8 h) a standard dinner ingested at 7 h 45 min. RESULTS: ICT immediately after eating was higher in IBS diarrhea predominant (IBS-D) patients than in the healthy cohort (23.1 +/- 2.4 vs. 17.5 +/- 2.8%, P = 0.059). ICT 2 h after lunch was similar between groups (P = 0.55). There was significant overall group differences in colonic transit 2 h post-lunch (P = 0.045), particularly in the IBS constipation predominant (IBS-C; GC6-GC4, delta 0.29 +/- 0.08) patients versus healthy volunteers (delta 0.56 +/- 0.12 GC units). CONCLUSIONS: After feeding, ICT is increased in IBS-D, whereas colonic transit is blunted in IBS-C.
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Colo/fisiologia , Ingestão de Alimentos/fisiologia , Trânsito Gastrointestinal/fisiologia , Íleo/fisiologia , Síndrome do Intestino Irritável/fisiopatologia , Administração Oral , Adulto , Feminino , Alimentos , Humanos , Síndrome do Intestino Irritável/diagnóstico por imagem , Masculino , Cintilografia , Valores de Referência , Tecnécio/administração & dosagemRESUMO
Irritable bowel syndrome and inflammatory bowel disease are major forms of chronic visceral pain, which affect over 15% of the global population. In order to identify new therapies, it is important to understand the underlying causes of chronic visceral pain. This review provides recent evidence demonstrating that inflammation or infection of the gastrointestinal tract triggers specific changes in the neuronal excitability of sensory pathways responsible for the transmission of nociceptive information from the periphery to the central nervous system. Specific changes in the expression and function of a variety of ion channels and receptors have been documented in inflammatory and chronic visceral pain conditions relevant to irritable bowel syndrome and inflammatory bowel disease. An increase in pro-nociceptive mechanisms enhances peripheral drive from the viscera and provides an underlying basis for enhanced nociceptive signalling during chronic visceral pain states. Recent evidence also highlights increases in anti-nociceptive mechanisms in models of chronic visceral pain, which present novel targets for pharmacological treatment of this condition.
Assuntos
Receptores de Superfície Celular/metabolismo , Dor Visceral/fisiopatologia , Animais , Doença Crônica , Humanos , Transdução de SinaisRESUMO
Irritable bowel syndrome (IBS) patients suffer from chronic abdominal pain and extraintestinal comorbidities, including overactive bladder (OAB) and interstitial cystitis/painful bladder syndrome (IC-PBS). Mechanistic understanding of the cause and time course of these comorbid symptoms is lacking, as are clinical treatments. Here, we report that colitis triggers hypersensitivity of colonic afferents, neuroplasticity of spinal cord circuits, and chronic abdominal pain, which persists after inflammation. Subsequently, and in the absence of bladder pathology, colonic hypersensitivity induces persistent hypersensitivity of bladder afferent pathways, resulting in bladder-voiding dysfunction, indicative of OAB/IC-PBS. Daily administration of linaclotide, a guanylate cyclase-C (GC-C) agonist that is restricted to and acts within the gastrointestinal tract, reverses colonic afferent hypersensitivity, reverses neuroplasticity-induced alterations in spinal circuitry, and alleviates chronic abdominal pain in mice. Intriguingly, daily linaclotide administration also reverses persistent bladder afferent hypersensitivity to mechanical and chemical stimuli and restores normal bladder voiding. Linaclotide itself does not inhibit bladder afferents, rather normalization of bladder function by daily linaclotide treatment occurs via indirect inhibition of bladder afferents via reduced nociceptive signaling from the colon. These data support the concepts that cross-organ sensitization underlies the development and maintenance of visceral comorbidities, while pharmaceutical treatments that inhibit colonic afferents may also improve urological symptoms through common sensory pathways.
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Agonistas da Guanilil Ciclase C/administração & dosagem , Hiperalgesia/tratamento farmacológico , Síndrome do Intestino Irritável/tratamento farmacológico , Plasticidade Neuronal/efeitos dos fármacos , Peptídeos/administração & dosagem , Bexiga Urinária Hiperativa/tratamento farmacológico , Vias Aferentes/efeitos dos fármacos , Animais , Colite/induzido quimicamente , Colo/efeitos dos fármacos , Colo/inervação , Modelos Animais de Doenças , Esquema de Medicação , Humanos , Hiperalgesia/induzido quimicamente , Hiperalgesia/complicações , Síndrome do Intestino Irritável/induzido quimicamente , Síndrome do Intestino Irritável/complicações , Masculino , Camundongos , Nociceptividade/efeitos dos fármacos , Resultado do Tratamento , Ácido Trinitrobenzenossulfônico/toxicidade , Bexiga Urinária/inervação , Bexiga Urinária Hiperativa/etiologiaRESUMO
BACKGROUND AND PURPOSE: Patients with irritable bowel syndrome suffer from chronic visceral pain (CVP) and limited analgesic therapeutic options are currently available. We have shown that α-conotoxin Vc1.1 induced activation of GABAB receptors on the peripheral endings of colonic afferents and reduced nociceptive signalling from the viscera. However, the analgesic efficacy of more stable, cyclized versions of Vc1.1 on CVP remains to be determined. EXPERIMENTAL APPROACH: Using ex vivo colonic afferent preparations from mice, we determined the inhibitory actions of cyclized Vc1.1 (cVc1.1) and two cVc1.1 analogues on mouse colonic nociceptors in healthy and chronic visceral hypersensitivity (CVH) states. Using whole-cell patch clamp recordings, we also assessed the inhibitory actions of these peptides on the neuronal excitability of colonic innervating dorsal root ganglion neurons. In vivo, the analgesic efficacy of these analogues was assessed by determining the visceromotor response to colorectal distension in healthy and CVH mice. KEY RESULTS: cVc1.1 and the cVc1.1 analogues, [C2H,C8F]cVc1.1 and [N9W]cVc1.1, all caused concentration-dependent inhibition of colonic nociceptors from healthy mice. Inhibition by these peptides was greater than those evoked by linear Vc1.1 and was substantially greater in colonic nociceptors from CVH mice. cVc1.1 also reduced excitability of colonic dorsal root ganglion neurons, with greater effect in CVH neurons. CVH mice treated with cVc1.1 intra-colonically displayed reduced pain responses to noxious colorectal distension compared with vehicle-treated CVH mice. CONCLUSIONS AND IMPLICATIONS: Cyclic versions of Vc1.1 evoked significant anti-nociceptive actions in CVH states, suggesting that they could be novel candidates for treatment of CVP. LINKED ARTICLES: This article is part of a themed section on Recent Advances in Targeting Ion Channels to Treat Chronic Pain. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.12/issuetoc.
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Dor Abdominal/tratamento farmacológico , Analgesia , Colo/efeitos dos fármacos , Conotoxinas/química , Conotoxinas/farmacologia , Modelos Animais de Doenças , Nociceptores/efeitos dos fármacos , Animais , Células Cultivadas , Doença Crônica , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Functional bowel disorder patients can suffer from chronic abdominal pain, likely due to visceral hypersensitivity to mechanical stimuli. As there is only a limited understanding of the basis of chronic visceral hypersensitivity (CVH), drug-based management strategies are ill defined, vary considerably, and include NSAIDs, opioids, and even anticonvulsants. We previously reported that the 1.1 subtype of the voltage-gated sodium (NaV; NaV1.1) channel family regulates the excitability of sensory nerve fibers that transmit a mechanical pain message to the spinal cord. Herein, we investigated whether this channel subtype also underlies the abdominal pain that occurs with CVH. We demonstrate that NaV1.1 is functionally upregulated under CVH conditions and that inhibiting channel function reduces mechanical pain in 3 mechanistically distinct mouse models of chronic pain. In particular, we use a small molecule to show that selective NaV1.1 inhibition (a) decreases sodium currents in colon-innervating dorsal root ganglion neurons, (b) reduces colonic nociceptor mechanical responses, and (c) normalizes the enhanced visceromotor response to distension observed in 2 mouse models of irritable bowel syndrome. These results provide support for a relationship between NaV1.1 and chronic abdominal pain associated with functional bowel disorders.
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Dor Crônica/tratamento farmacológico , Colo/efeitos dos fármacos , Síndrome do Intestino Irritável/complicações , Dor Visceral/tratamento farmacológico , Bloqueadores do Canal de Sódio Disparado por Voltagem/administração & dosagem , Animais , Dor Crônica/diagnóstico , Dor Crônica/etiologia , Dor Crônica/patologia , Colo/inervação , Colo/patologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Estabilidade de Medicamentos , Gânglios Espinais/citologia , Humanos , Síndrome do Intestino Irritável/induzido quimicamente , Síndrome do Intestino Irritável/patologia , Masculino , Dose Máxima Tolerável , Camundongos , Canal de Sódio Disparado por Voltagem NAV1.1/metabolismo , Nociceptores/efeitos dos fármacos , Nociceptores/metabolismo , Medição da Dor , Ácido Trinitrobenzenossulfônico/administração & dosagem , Ácido Trinitrobenzenossulfônico/toxicidade , Dor Visceral/diagnóstico , Dor Visceral/etiologia , Dor Visceral/patologiaRESUMO
Afferent nerves not only convey information concerning normal physiology, but also signal disturbed homeostasis and pathophysiological processes of the different organ systems from the periphery towards the central nervous system. As such, the increased activity or 'sensitization' of mesenteric afferent nerves has been allocated an important role in the pathophysiology of visceral hypersensitivity and abdominal pain syndromes. Mesenteric afferent nerve activity can be measured in vitro in an isolated intestinal segment that is mounted in a purpose-built organ bath and from which the splanchnic nerve is isolated, allowing researchers to directly assess nerve activity adjacent to the gastrointestinal segment. Activity can be recorded at baseline in standardized conditions, during distension of the segment or following the addition of pharmacological compounds delivered intraluminally or serosally. This technique allows the researcher to easily study the effect of drugs targeting the peripheral nervous system in control specimens; besides, it provides crucial information on how neuronal activity is altered during disease. It should be noted however that measuring afferent neuronal firing activity only constitutes one relay station in the complex neuronal signaling cascade, and researchers should bear in mind not to overlook neuronal activity at other levels (e.g., dorsal root ganglia, spinal cord or central nervous system) in order to fully elucidate the complex neuronal physiology in health and disease. Commonly used applications include the study of neuronal activity in response to the administration of lipopolysaccharide, and the study of afferent nerve activity in animal models of irritable bowel syndrome. In a more translational approach, the isolated mouse intestinal segment can be exposed to colonic supernatants from IBS patients. Furthermore, a modification of this technique has been recently shown to be applicable in human colonic specimens.
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Síndrome do Intestino Irritável , Mesentério , Neurônios Aferentes , Animais , Colo , Modelos Animais de Doenças , Gânglios Espinais , Humanos , Jejuno , Camundongos , Técnicas de Cultura de ÓrgãosRESUMO
OBJECTIVES: Experiments using P2X3 knock-out mice or more general P2X receptor antagonists suggest that P2X3 receptors contribute to visceral hypersensitivity. We aimed to investigate the effect of the selective P2X3 antagonist A-317491 on visceral sensitivity under physiological conditions, during acute colitis and in the post-inflammatory phase of colitis. METHODS: Trinitrobenzene sulphonic-acid colitis was monitored by colonoscopy: on day 3 to confirm the presence of colitis and then every 4 days, starting from day 10, to monitor convalescence and determine the exact timepoint of endoscopic healing in each rat. Visceral sensitivity was assessed by quantifying visceromotor responses to colorectal distension in controls, rats with acute colitis and post-colitis rats. A-317491 was administered 30 min prior to visceral sensitivity testing. Expression of P2X3 receptors (RT-PCR and immunohistochemistry) and the intracellular signalling molecules cdk5, csk and CASK (RT-PCR) were quantified in colonic tissue and dorsal root ganglia. ATP release in response to colorectal distension was measured by luminiscence. RESULTS: Rats with acute TNBS-colitis displayed significant visceral hypersensitivity that was dose-dependently, but not fully, reversed by A-317491. Hypersenstivity was accompanied by an increased colonic release of ATP. Post-colitis rats also displayed visceral hypersensitivity that was dose-dependently reduced and fully normalized by A-317491 without increased release of ATP. A-317491 did not modify visceral sensitivity in controls. P2X3 mRNA and protein expression in the colon and dorsal root ganglia were similar in control, acute colitis and post-colitis groups, while colonic mRNA expression of cdk5, csk and CASK was increased in the post-colitis group only. CONCLUSIONS: These findings indicate that P2X3 receptors are not involved in sensory signaling under physiological conditions whereas they modulate visceral hypersensitivity during acute TNBS-colitis and even more so in the post-inflammatory phase, albeit via different mechanisms of sensitization, validating P2X3 receptors as potential new targets in the treatment of abdominal pain syndromes.
Assuntos
Colite/metabolismo , Hiperalgesia/metabolismo , Inflamação/metabolismo , Receptores Purinérgicos P2X3/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Colite/induzido quimicamente , Colite/fisiopatologia , Colo/metabolismo , Colo/fisiopatologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Hiperalgesia/induzido quimicamente , Hiperalgesia/fisiopatologia , Inflamação/induzido quimicamente , Inflamação/fisiopatologia , Masculino , Fenóis/farmacologia , Compostos Policíclicos/farmacologia , Antagonistas do Receptor Purinérgico P2X/farmacologia , Ratos , Ratos Sprague-Dawley , Ácido TrinitrobenzenossulfônicoRESUMO
Tachykinins are important mediators of neuroneuronal and neuromuscular transmission in the gastrointestinal tract, however their contribution to colonic peristalsis in mice remains unclear. Therefore, our aim was to characterise the functional role of tachykinins in mediating peristalsis by evaluating the effect of selective tachykinin NK(1), NK(2) and NK(3) receptor agonists and antagonists on in vitro colonic peristaltic activity in mice. Using a modified Trendelenburg set-up, gradual distension of proximal and distal colonic segments evoked rhythmic, aborally migrating contractions. Peristaltic activity was assessed by quantifying the amplitude and interval of the corresponding pressure waves. Stimulation of NK(1) receptors showed regional differences as both the pressure amplitude and interval were enhanced in the distal colon without affecting peristalsis proximally. Blockade of NK(1) receptors reduced the peristaltic pressure amplitude in the proximal and distal colon while the interval was not significantly altered. NK(2) receptor stimulation resulted in a modest enhancement of the amplitude in proximal and distal segments and a slightly prolonged interval distally. Blockade of NK(2) receptors reduced the peristaltic pressure amplitude and interval in the distal colon. NK(3) receptor stimulation significantly augmented the amplitude in both segments and prolonged the interval distally. However, NK(3) receptor blockade had no effect on peristaltic activity. In conclusion, tachykinins contribute to colonic peristalsis in mice by acting mainly on NK(1) and NK(2) receptors and their effects show a proximal-to-distal gradient. NK(3) receptors might play a role in conditions of excess tachykinin release but appear not to be involved under the conditions of the present study.
Assuntos
Colo/fisiologia , Peristaltismo , Receptores de Taquicininas/metabolismo , Animais , Atropina/farmacologia , Colo/efeitos dos fármacos , Colo/metabolismo , Hexametônio/farmacologia , Técnicas In Vitro , Camundongos , Peristaltismo/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Receptores de Taquicininas/agonistas , Receptores de Taquicininas/antagonistas & inibidores , Taquicininas/metabolismo , Tetrodotoxina/farmacologiaRESUMO
IMPORTANCE OF THE FIELD: Chronic constipation has a high prevalence, and current medical and pharmacological therapies do not restore normal bowel function in all patients. AREAS COVERED IN THE REVIEW: A PubMed search (1965 - 2009) using the following terms alone or in combination: prucalopride, 5-HT(4), R093877, safety, toxicity, pharmacokinetics, pharmacodynamics, transit, cardiac, hERG, arrhythmia, potassium current, elderly. WHAT THE READER WILL GAIN: Understanding of the mechanisms of action, safety, efficacy and indications for prucalopride in patients with chronic constipation. TAKE HOME MESSAGE: Prucalopride is an efficacious and generally safe, new therapeutic option in the management of chronic constipation.