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Rodriguez GM, Gater DR. Neurogenic Bowel and Management after Spinal Cord Injury: A Narrative Review. J Pers Med 2022; 12:jpm12071141. [PMID: 35887638 PMCID: PMC9324073 DOI: 10.3390/jpm12071141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 07/02/2022] [Accepted: 07/12/2022] [Indexed: 11/16/2022] Open
Abstract
People with spinal cord injury (SCI) suffer from the sequela of neurogenic bowel and its disabling complications primarily constipation, fecal incontinence, and gastrointestinal (GI) symptoms. Neurogenic bowel is a functional bowel disorder with a spectrum of defecatory disorders as well as colonic and gastrointestinal motility dysfunction. This manuscript will review the anatomy and physiology of gastrointestinal innervation, as well as the pathophysiology associated with SCI. It will provide essential information on the recent guidelines for neurogenic bowel assessment and medical management. This will allow medical providers to partner with their patients to develop an individualized bowel plan utilizing a combination of various pharmacological, mechanical and surgical interventions that prevent complications and ensure successful management and compliance. For people with SCI and neurogenic bowel dysfunction, the fundamental goal is to maintain health and well-being, promote a good quality of life and support active, fulfilled lives in their homes and communities.
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Affiliation(s)
- Gianna M. Rodriguez
- Department of Physical Medicine and Rehabilitation, University of Michigan College of Medicine, Ann Arbor, MI 48108, USA
- Correspondence:
| | - David R. Gater
- Department of Physical Medicine and Rehabilitation, University of Miami Miller School of Medicine, Miami, FL 33136, USA;
- Christine E. Lynn Rehabilitation Center for the Miami Project to Cure Paralysis, Miami, FL 33136, USA
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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Impaired visceral pain-related functions of the midbrain periaqueductal gray in rats with colitis. Brain Res Bull 2022; 182:12-25. [DOI: 10.1016/j.brainresbull.2022.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 01/12/2022] [Accepted: 02/03/2022] [Indexed: 11/18/2022]
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Cao DY, Hu B, Xue Y, Hanson S, Dessem D, Dorsey SG, Traub RJ. Differential Activation of Colonic Afferents and Dorsal Horn Neurons Underlie Stress-Induced and Comorbid Visceral Hypersensitivity in Female Rats. THE JOURNAL OF PAIN 2021; 22:1283-1293. [PMID: 33887444 PMCID: PMC8500917 DOI: 10.1016/j.jpain.2021.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 03/16/2021] [Accepted: 04/02/2021] [Indexed: 12/19/2022]
Abstract
Chronic Overlapping Pain Conditions, including irritable bowel syndrome (IBS) and temporomandibular disorder (TMD), represent a group of idiopathic pain conditions that likely have peripheral and central mechanisms contributing to their pathology, but are poorly understood. These conditions are exacerbated by stress and have a female predominance. The presence of one condition predicts the presence or development of additional conditions, making this a significant pain management problem. The current study was designed to determine if the duration and magnitude of peripheral sensitization and spinal central sensitization differs between restraint stress-induced visceral hypersensitivity (SIH) and chronic comorbid pain hypersensitivity (CPH; stress during pre-existing orofacial pain). SIH in female rats, as determined by the visceromotor response, persisted at least four but resolved by seven weeks. In contrast, CPH persisted at least seven weeks. Surprisingly, colonic afferents in both SIH and CPH rats were sensitized at seven weeks. CPH rats also had referred pain through seven weeks, but locally anesthetizing the colon only attenuated the referred pain through four weeks, suggesting a transition to colonic afferent independent central sensitization. Different phenotypes of dorsal horn neurons were sensitized in the CPH rats seven weeks post stress compared to four weeks or SIH rats. The current study suggests differential processing of colonic afferent input to the lumbosacral spinal cord contributes to visceral hypersensitivity during comorbid chronic pain conditions. PERSPECTIVE: Chronic Overlapping Pain Conditions represent a unique challenge in pain management. The diverse nature of peripheral organs hinders a clear understanding of underlying mechanisms accounting for the comorbidity. This study highlights a mismatch between the condition-dependent behavior and peripheral and spinal mechanisms that contribute to visceral pain hypersensitivity.
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Affiliation(s)
- Dong-Yuan Cao
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, Maryland; Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China
| | - Bo Hu
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, Maryland; Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, Research Center of Stomatology, Xi'an Jiaotong University College of Stomatology, Xi'an, Shaanxi, P. R. China
| | - Yang Xue
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, Maryland; Department of Prosthodontics, Peking University School and Hospital of Stomatology, Haidian District, Beijing, P. R. China
| | - Shelby Hanson
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, Maryland
| | - Dean Dessem
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, Maryland; UM Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Baltimore, Maryland
| | - Susan G Dorsey
- Department of Pain and Translational Symptom Science, University of Maryland School of Nursing, Baltimore, Maryland; UM Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Baltimore, Maryland
| | - Richard J Traub
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, Maryland; UM Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Baltimore, Maryland.
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Differential responses of neurons in the rat caudal ventrolateral medulla to visceral and somatic noxious stimuli and their alterations in colitis. Brain Res Bull 2019; 152:299-310. [PMID: 31377442 DOI: 10.1016/j.brainresbull.2019.07.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 07/15/2019] [Accepted: 07/30/2019] [Indexed: 02/06/2023]
Abstract
Visceral and somatic types of pain have been reported to manifest crucial differences not only in the experience, but also in their peripheral and central processing. However, the precise neuronal mechanisms that responsible for the modality-specific transmission of pain signals, especially at the supraspinal level, remain unclear. Very little is known also about the potential involvement of such mechanisms in the development of viscero-somatic hyperalgesia. Therefore, in the present study performed on urethane-anesthetized adult male Wistar rats we examined responses of neurons in the caudal ventrolateral medulla (CVLM)-the first site for supraspinal processing of both internal and external pain signals-to visceral (colorectal distension, CRD) and somatic (squeezing of the tail) noxious stimulations and evaluated alterations in response properties of these cells after the induction of colitis. It has been found out that the CVLM of healthy control rats, along with harboring of cells excited by both stimulations (23.7%), contained neurons that were activated by either visceral (31.9%) or somatic noxious stimuli (44.4%). In inflamed animals, the percentages of the visceral and somatic nociceptive cells were decreased (to 18.3% and 34.3%, correspondingly) and the number of bimodal neurons was increased (up to 47.4%); these alterations were associated with substantially enhanced responses of both the modality-specific and convergent CVLM neurons not only to CRD, but also to squeezing of the tail. Under these conditions, visceral and somatic pain stimuli induced similar changes in arterial blood pressure and respiratory rate, whereas in the absence of intestinal inflammation noxious CRD and tail stimulation evoked predominantly divergent autonomic reactions. The data obtained can benefit to a deeper understanding of the neuronal mechanisms that underlie differential supraspinal processing of visceral and somatic noxious stimuli and can potentially contribute to the realization of specific cardiovascular and respiratory accompaniments inherent to a particular type of pain. Therewith, results of the study elucidate colitis-induced alterations in these mechanisms, which may be responsible for the combined development of visceral hypersensitivity and somatic hyperalgesia.
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Colitis-induced alterations in response properties of visceral nociceptive neurons in the rat caudal medulla oblongata and their modulation by 5-HT3 receptor blockade. Brain Res Bull 2018; 142:183-196. [PMID: 30031817 DOI: 10.1016/j.brainresbull.2018.07.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 06/15/2018] [Accepted: 07/17/2018] [Indexed: 12/17/2022]
Abstract
There is considerable clinical and experimental evidence that intestinal inflammation is associated with altered visceral nociceptive processing in the spinal cord and brain, but the underlying neuronal mechanisms, especially acting at the supraspinal level, remain unclear. Considering that the caudal ventrolateral medulla (CVLM) and the nucleus tractus solitarius (NTS) are the first sites for supraspinal processing of visceral pain signals, in the present study we evaluated the experimental colitis-induced changes in response properties of CVLM and NTS medullary neurons to noxious colorectal distension (CRD) in urethane-anesthetized adult male Wistar rats. To determine if gut inflammation alters the 5-HT3 receptor-dependent modulation of visceral pain-related CVLM and NTS cells, we examined the effects of intravenously administered selective 5-HT3 antagonist granisetron on ongoing and CRD-evoked activity of CVLM and NTS neurons in healthy control and colitic animals. In the absence of colonic pathology, the CVLM neurons were more excited by noxious CRD that the NTS cells, which demonstrated a greater tendency to be inhibited by the stimulation. The difference was eliminated after the development of colitis due to the increase in the proportion of CRD-excited neurons in both medullary regions associated with enhanced magnitude of the neuronal nociceptive responses. Intravenous granisetron (1 or 2 mg/kg) produced the dose-dependent suppression of the ongoing and evoked firing of CRD-excited cells within both the CVLM and NTS in normal conditions as well as was able to substantially reduce excitability of the caudal medullary neurons in the presence of colonic inflammation, arguing for the potential efficacy of the 5-HT3 receptor blockade with granisetron against both acute and inflammatory abdominal pain. Taken together, the data obtained can contribute to a deeper understanding of supraspinal serotonergic mechanisms responsible for the persistence of visceral hypersensitivity and hyperalgesia triggered by colonic inflammation.
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Lyubashina O, Sivachenko I. The 5-HT 4 receptor-mediated inhibition of visceral nociceptive neurons in the rat caudal ventrolateral medulla. Neuroscience 2017; 359:277-288. [DOI: 10.1016/j.neuroscience.2017.07.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/26/2017] [Accepted: 07/17/2017] [Indexed: 12/23/2022]
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Soler JM, Amarenco G. [Noxious stimuli and neurogenic overactive bladder]. Prog Urol 2015; 25:455-60. [PMID: 25883054 DOI: 10.1016/j.purol.2015.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 03/10/2015] [Accepted: 03/10/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES Describe the relationships between neurogenic overactive bladder and noxious stimuli. METHODS Relevant data from the literature were identified primarily through a Medline search of articles published through July 2014. The search terms included overactive bladder, central nervous system, noxious visceral and cutaneous stimuli. RESULTS Overactive bladder often due to overactive detrusor is the most common symptom observed in central neurogenic bladder (70 to 80% in case of spinal cord injury). Pathophysiological mechanisms are various and numerous. Noxious cutaneous stimuli may determine, or maintain, these symptoms by increased afferent inputs in segmental levels, particularly S2S3 levels, determining exaggerated visceral, muscle and bladder responses depending on this considered medullary level. These modifications are only observed in case of central neurogenic lesions secondary to spinal cord involvement. Animal researches have precised the role of lack of the supra-segmental inhibition. CONCLUSIONS In presence of neurogenic overactive bladder, it is always necessary to track down noxious stimuli particularly in case of modifications of clinical or urodynamic status or when the usual treatments, generally anticholinergic drugs, have a reduced efficacy. Treatment is first focused on the suppression of these noxious cutaneous stimuli.
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Affiliation(s)
- J-M Soler
- Centre Bouffard-Vercelli-Cap Peyrefitte, 66290 Cerbère, France; UPMC, GRC 01, GREEN, group of clinical research in neuro-urology, Sorbonne universités, université Paris 06, 75005 Paris, France.
| | - G Amarenco
- UPMC, GRC 01, GREEN, group of clinical research in neuro-urology, Sorbonne universités, université Paris 06, 75005 Paris, France; Service de neuro-urologie, hôpital Tenon, AP-HP, 75020 Paris, France
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Miranda A, Mickle A, Bruckert M, Kannampalli P, Banerjee B, Sengupta JN. NMDA receptor mediates chronic visceral pain induced by neonatal noxious somatic stimulation. Eur J Pharmacol 2014; 744:28-35. [PMID: 25281204 DOI: 10.1016/j.ejphar.2014.09.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 09/22/2014] [Accepted: 09/23/2014] [Indexed: 12/29/2022]
Abstract
NMDA receptors (NMDAR) are important in the development and maintenance of central sensitization. Our objective was to investigate the role of spinal neurons and NMDAR in the maintenance of chronic visceral pain. Neonatal rats were injected with acidic saline adjusted to pH 4.0 in the gastrocnemius muscle every other day for 12 days. In adult rats, NR1 and NR2B subunits were examined in the lumbo-sacral (LS) spinal cord. A baseline, visceromotor response (VMR) to graded colorectal distension (CRD) was recorded before and after administration of the NMDA antagonist, CGS-19755. Extracellular recordings were performed from CRD-sensitive LS spinal neurons and pelvic nerve afferents (PNA) before and after CGS-19755. Rats that received pH 4.0 saline injections demonstrated a significant increase in the expression NR2B subunits and VMR response to CRD>20 mmHg. CGS-19755 (i.v. or i.t.) had no effect in naïve rats, but significantly decreased the response to CRD in pH 4.0 saline injected rats. CGS-19755 had no effect on the spontaneous firing of SL-A, but decreased that of SL-S. Similarly, CGS-19755 attenuates the responses of SL-S neurons to CRD, but had no effect on SL-A neurons or on the response characteristics of PNA fibers. Neonatal noxious somatic stimulation results in chronic visceral hyperalgesia and sensitizes a specific subpopulation of CRD-sensitive spinal neurons. The sensitization of these SL-S spinal neurons is attenuated by the NMDAR antagonist. The results of this study suggest that spinal NMDARs play an important role in the development of hyperalgesia early in life.
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Affiliation(s)
- Adrian Miranda
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, United States.
| | - Aaron Mickle
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Mitchell Bruckert
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Pradeep Kannampalli
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Banani Banerjee
- Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Jyoti N Sengupta
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Division of Gastroenterology and Hepatology, Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, United States
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Ghorbani MLM, Qin C, Wu M, Farber JP, Sheykhzade M, Fjalland B, Nyborg NCB, Foreman RD. Characterization of upper thoracic spinal neurons receiving noxious cardiac and/or somatic inputs in diabetic rats. Auton Neurosci 2011; 165:168-77. [PMID: 21862419 DOI: 10.1016/j.autneu.2011.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 07/19/2011] [Accepted: 07/25/2011] [Indexed: 01/11/2023]
Abstract
The aim of the present study was to examine spinal processing of cardiac and somatic nociceptive input in rats with STZ-induced diabetes. Type 1 diabetes was induced with streptozotocin (50mg/kg) in 14 male Sprague-Dawley rats and citrate buffer was injected in 14 control rats. After 4-11 weeks, the rats were anesthetized with pentobarbital, ventilated and paralyzed. A laminectomy enabled extracellular recording of T(3) spinal cord neuronal activity. Intrapericardial administration of a mixture of algogenic chemicals (bradykinin, serotonin, prostaglandin E(2) (all at 10(-5)M), and adenosine (10(-3)M)) was applied to activate nociceptors of cardiac afferent nerve endings. Furthermore, somatic receptive properties were examined by applying innocuous (brush and light pressure) and noxious (pinch) cutaneous mechanical stimuli. Diabetes-induced increases in spontaneous activity were observed in subsets of neurons exhibiting long-lasting excitatory responses to administration of the algogenic mixture. Algogenic chemicals altered activity of a larger proportion of neurons from diabetic animals (73/111) than control animals (55/115, P<0.05). Some subtypes of neurons exhibiting long-lasting excitatory responses, elicited prolonged duration and others, had a shortened latency. Some neurons exhibiting short-lasting excitatory responses in diabetic animals elicited a shorter latency and some a decreased excitatory change. The size of the somatic receptive field was increased for cardiosomatic neurons from diabetic animals. Cutaneous somatic mechanical stimulation caused spinal neurons to respond with a mixture of hyper- and hypoexcitability. In conclusion, diabetes induced changes in the spinal processing of cardiac input and these might contribute to cardiovascular autonomic neuropathy in patients with diabetes.
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Affiliation(s)
- Marie Louise M Ghorbani
- Dept. Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, Copenhagen University, DK-2100 Copenhagen, Denmark.
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Matricon J, Gelot A, Etienne M, Lazdunski M, Muller E, Ardid D. Spinal cord plasticity and acid-sensing ion channels involvement in a rodent model of irritable bowel syndrome. Eur J Pain 2011; 15:335-43. [PMID: 20888277 DOI: 10.1016/j.ejpain.2010.08.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 08/09/2010] [Accepted: 08/09/2010] [Indexed: 10/19/2022]
Abstract
Irritable bowel syndrome (IBS) is a common functional gastro-intestinal disorder characterized by intractable chronic abdominal pain. In this study, we examined the possible spinal mechanisms underlying colonic hypersensitivity (CHS) using a non-inflammatory rat model of IBS induced by rectal enemas of butyrate, a short-chain fatty acid. We hypothesized that spinal plasticity could be responsible for CHS and that ASIC channels, which are known to support pain-elicited currents in the spinal cord, could contribute to central sensitization in our model of IBS. First, in order to determine if visceral pain relies on changes in spinal activity, we analyzed Fos expression in the spinal cord of rats treated with butyrate following a challenge with repetitive noxious colorectal distension. We found that Fos immunoreactivity was increased in thoracic T10-11-12, lumbar L1-2-6 and sacral S1 spinal segments. In control rats treated with saline, noxious repetitive colorectal distensions evoked Fos expression only in L1-2-6 and S1 spinal segments. Secondly, intrathecal injection of PcTx1, a specific ASIC1A antagonist, in the lumbar spinal cord completely prevented the development of CHS induced by butyrate. ASIC1 and 2 mRNAs, especially ASIC1A, were upregulated in the lumbar spinal cord. ASIC1A could thus contribute to spinal sensitization in our model of IBS, as it is supported by spinal colocalization of ASIC1A and Fos proteins. The whole data pinpoint a potential critical role of thoracic spinal cord in non-inflammatory pain states such as IBS and suggest that ASIC channels are part of the molecular effectors of central sensitization leading to visceral pain.
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Affiliation(s)
- Julien Matricon
- Clermont Université, Université d'Auvergne, Pharmacologie fondamentale et clinique de douleur, Laboratoire de Pharmacologie Médicale, BP 10448, F-63000 Clermont-Ferrand, Inserm U 766, F-63001 Clermont-Ferrand, France
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Traub RJ, Tang B, Ji Y, Pandya S, Yfantis H, Sun Y. A rat model of chronic postinflammatory visceral pain induced by deoxycholic acid. Gastroenterology 2008; 135:2075-83. [PMID: 19000677 PMCID: PMC2782449 DOI: 10.1053/j.gastro.2008.08.051] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 08/18/2008] [Accepted: 08/25/2008] [Indexed: 12/16/2022]
Abstract
BACKGROUND & AIMS Chronic visceral hyperalgesia is considered an important pathophysiologic symptom in irritable bowel syndrome (IBS); previous gastrointestinal inflammation is a potent etiologic factor for developing IBS. Although there are several animal models of adult visceral hypersensitivity after neonatal perturbation or acute colonic irritation/inflammation, current models of postinflammatory chronic visceral hyperalgesia are unsatisfactory. The aim of this study was to establish a model of chronic visceral hyperalgesia after colonic inflammation in the rat. METHODS Deoxycholic acid (DCA) was instilled into the rat colon daily for 3 days and animals were tested for up to 4 weeks. RESULTS DCA induced mild, transient colonic inflammation within 3 days that resolved within 3 weeks. An exaggerated visceromotor response, referred pain to mechanical stimulation, increased spinal Fos expression, and colonic afferent and dorsal horn neuron activity were apparent by 1 week and persisted for at least 4 weeks, indicating chronic dorsal horn hyperexcitability and visceral hyperalgesia. There was no spontaneous pain, based on open field behavior. There was a significant increase in opioid-receptor activity. CONCLUSIONS DCA induces mild, transient colitis, resulting in persistent visceral hyperalgesia and referred pain in rats, modeling some aspects of postinflammatory IBS.
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Affiliation(s)
- Richard J. Traub
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, MD
| | - Bin Tang
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, MD
| | - Yaping Ji
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, MD
| | - Sangeeta Pandya
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, MD
| | - Harris Yfantis
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD,Veterans Administration Maryland Health Care System, Department of Pathology and Laboratory Medicine, Baltimore, MD
| | - Ying Sun
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, MD
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Lynn PA, Chen BN, Zagorodnyuk VP, Costa M, Brookes SJH. TNBS-induced inflammation modulates the function of one class of low-threshold rectal mechanoreceptors in the guinea pig. Am J Physiol Gastrointest Liver Physiol 2008; 295:G862-71. [PMID: 18755810 PMCID: PMC2575914 DOI: 10.1152/ajpgi.00585.2007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The effects of trinitrobenzene sulfonic acid (TNBS)-induced inflammation on specialized, low-threshold, slowly adapting rectal mechanoreceptors were investigated in the guinea pig. Under isoflurane anesthesia, 300 microl saline or TNBS (15 mg/ml) in 30% ethanol was instilled 7 cm from the anal sphincter. Six or 30 days later, single unit extracellular recordings were made from rectal nerve trunks in flat-sheet in vitro preparations attached to a mechanical tissue stretcher. TNBS treatment caused macroscopic ulceration of the rectal mucosa at 6 days, which fully resolved by 30 days. Muscle contractility was unaffected by TNBS treatment. At 6 days posttreatment, responses of low-threshold rectal mechanoreceptors to circumferential stretch were increased, and the proportion of afferents responding with von Frey hair thresholds <or=0.1 mN and mechanoreceptor excitability in response to electrical stimulation were increased in TNBS-treated tissue, suggesting increased sensitivity of the mechanotransducer. Mechanoreceptor function at 30 days posttreatment was in most cases unchanged. The inflammatory mediator prostaglandin E(2) (1 microM) activated mechanoreceptors (6 days) in conjunction with contractile activity, but capsaicin (1 microM) failed to activate mechanoreceptors. Bradykinin (1 microM) activated mechanoreceptors independently of contractile activity and responses to stretch were increased in the presence of bradykinin. Both capsaicin and bradykinin activated unidentified stretch-insensitive afferents independently of contractile activity. Mechanoreceptor function is modulated at 6 days posttreatment but not at 30 days, suggesting a moderate increase in mechanoreceptor sensitivity in inflamed tissue but not after recovery. Other unclassified stretch-insensitive afferents are responsive to inflammatory mediators and capsaicin and may be involved in aspects of visceral sensation.
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Affiliation(s)
- P. A. Lynn
- Department of Human Physiology and Centre for Neuroscience Flinders University, Bedford Park, Australia
| | - B. N. Chen
- Department of Human Physiology and Centre for Neuroscience Flinders University, Bedford Park, Australia
| | - V. P. Zagorodnyuk
- Department of Human Physiology and Centre for Neuroscience Flinders University, Bedford Park, Australia
| | - M. Costa
- Department of Human Physiology and Centre for Neuroscience Flinders University, Bedford Park, Australia
| | - S. J. H. Brookes
- Department of Human Physiology and Centre for Neuroscience Flinders University, Bedford Park, Australia
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Abstract
The investigative evidence and emerging concepts in neurogastroenterology implicate dysfunctions at the levels of the enteric and central nervous systems as underlying causes of the prominent symptoms of many of the functional gastrointestinal disorders. Neurogastroenterological research aims for improved understanding of the physiology and pathophysiology of the digestive subsystems from which the arrays of functional symptoms emerge. The key subsystems for defecation-related symptoms and visceral hyper-sensitivity are the intestinal secretory glands, the musculature and the nervous system that controls and integrates their activity. Abdominal pain and discomfort arising from these systems adds the dimension of sensory neurophysiology. This review details current concepts for the underlying pathophysiology in terms of the physiology of intestinal secretion, motility, nervous control, sensing function, immuno-neural communication and the brain-gut axis.
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Miranda A, Peles S, Shaker R, Rudolph C, Sengupta JN. Neonatal nociceptive somatic stimulation differentially modifies the activity of spinal neurons in rats and results in altered somatic and visceral sensation. J Physiol 2006; 572:775-87. [PMID: 16513666 PMCID: PMC1779998 DOI: 10.1113/jphysiol.2006.108258] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The role ofintramuscular, low pH saline injections during the neonatal period in the development and maintenance of visceral hyperalgesia has not been systematically studied. We aimed to investigate alterations in visceral sensation and neural circuitry that result from noxious stimuli in early life. Neonatal male Sprague-Dawley rats received sterile saline injections of pH 4.0 or 7.4 in the gastrocnemius muscle starting at postnatal day 8. Injections were given unilaterally every other day for 12 days ending on postnatal day 20. A third group received needle prick only on the same shedule as the second group, while a fourth group was left naïve. At 2 months of age, rats underwent assessment of cutaneous and deep somatic sensitivity using von Frey filaments and gastrocnemius muscle pinch, respectively. A visceromotor response (VMR) to graded colorectal distension (CRD; 10-80 mmHg for 30 s with 180 s interstimulus intervals) was recorded. Extracellular single-unit recordings from the thoracolumbar spinal neurons (T13-L1) were performed in adult pH 4.0 injected and naïve controls. There was no difference in the threshold for response to mechanical stimulation of the paw in rats injected with pH 4.0 saline compared to all other groups. Conversely, rats treated with pH 4.0 saline showed a significant bilateral reduction in withdrawal threshold to muscle pinch as adults (P < 0.05). At colorectal distensions > or = 20 mmHg, an increase in the VMR was observed in the pH 4.0 injected group compared to all other groups (P < 0.05). Spinal neurons were classified as short latency abrupt (SL-A) or short latency sustained (SL-S). Spontaneous firing of SL-S (20.6 +/- 2.2 impulses s(-1)), but not SL-A neurons (5.3 +/- 0.9 impulses s(-1)) in the pH 4.0 treated rats was significantly higher than in control rats (SL-S, 2.6 +/- 0.8 impulses s(-1); SL-A, 3.1 +/- 0.7 impulses s(-1)). The response of SL-S neurons to CRD in the pH 4.0 group was significantly higher at distension pressures > or = 20 mmHg. Nociceptive somatic stimulation in neonatal rats results in chronic deep somatic and visceral hyperalgesia in adulthood. Colorectal distension-sensitive SL-S neurons are primarily sensitized to neonatal somatic stimulation.
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Affiliation(s)
- Adrian Miranda
- Division of Gastroenterology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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Larsson MH, Rapp L, Lindström E. Effect of DSS-induced colitis on visceral sensitivity to colorectal distension in mice. Neurogastroenterol Motil 2006; 18:144-52. [PMID: 16420293 DOI: 10.1111/j.1365-2982.2005.00736.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The present study aimed at evaluating the effect of dextran sodium sulphate (DSS)-induced colitis on visceral sensitivity, measured as the visceromotor response (VMR) to colorectal distension (CRD) in BALB/c and C57Bl/6 male mice. Inflammation was induced by the addition of 4% DSS to the drinking water for 5 (C57Bl/6) or 6-7 days (BALB/c). Parallel groups were used to monitor histopathological changes and visceral sensitivity. Pseudo-affective visceral pain responses were evoked using an increasing phasic CRD paradigm (10-60 mmHg) in conscious mice on predetermined days (pretreatment controls, 12, 16, 20, 30, 40 and 51). In both mouse strains, significant histopathological changes developed between days 2 and 5 of DSS treatment, and persisted until day 12 (P < 0.05). On day 15, inflammatory scores were reduced by about 50%. Despite evidence of inflammation in DSS-treated mice, no differences could be shown in the VMR to CRD between DSS-treated mice and controls at any time point tested. In addition, no differences were seen before and after DSS treatment in the same group of mice. In conclusion, these data suggest that DSS-induced colonic inflammation does not affect the visceral sensitivity to CRD, neither at short or long term, in BALB/c or C57Bl/6 male mice.
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Affiliation(s)
- M H Larsson
- Department of Integrative Pharmacology, Gastrointestinal Biology, AstraZeneca R&D Mölndal, Mölndal, Sweden.
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Wang G, Tang B, Traub RJ. Differential processing of noxious colonic input by thoracolumbar and lumbosacral dorsal horn neurons in the rat. J Neurophysiol 2005; 94:3788-94. [PMID: 16093344 DOI: 10.1152/jn.00230.2005] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previous studies suggest the lumbosacral (LS) spinal cord processes acute colorectal stimuli whereas the thoracolumbar (TL) and LS spinal segments process inflammatory stimuli. In this study, the effects of colorectal distention (CRD) on TL and LS dorsal horn neuronal activity were recorded in Nembutal-anesthetized male rats both with and without colonic inflammation. Both single cells (before and after inflammation) and populations (multiple cells from noninflamed or inflamed rats) were studied. CRD-responsive neurons had excitatory Abrupt (on-off with stimulus) or Sustained (prolonged after discharge) responses or were Inhibited by CRD. In noninflamed rats, a significantly greater percentage of LS neurons (63% Abrupt, 27% Sustained) were excited by CRD than TL neurons (61% Abrupt, 3% Sustained). The remaining cells were Inhibited (10% LS, 36% TL). LS Abrupt neurons had lower thresholds and greater response magnitudes to CRD compared with TL Abrupt neurons. After colonic inflammation, TL neurons became more excitable: the percentage of Inhibited neurons decreased, the response magnitude of Abrupt neurons increased, and the threshold decreased. In contrast, in single-cell recordings, the response of LS Sustained neurons increased, whereas LS Abrupt neurons decreased. These data suggest that in noninflamed rats, the net response to CRD of TL visceroceptive spinal sensory neurons is less than that of LS neurons. Colonic inflammation increases the net response of TL neurons and differentially modulates the response of LS neurons. These differences may contribute to the functional dichotomy between the TL and LS spinal segments in processing acute and inflammatory colorectal pain.
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Affiliation(s)
- Gexin Wang
- Department of Biomedical Sciences, Dental School, University of Maryland, Baltimore, 21201, USA
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Peles S, Miranda A, Shaker R, Sengupta JN. Acute nociceptive somatic stimulus sensitizes neurones in the spinal cord to colonic distension in the rat. J Physiol 2004; 560:291-302. [PMID: 15284340 PMCID: PMC1665216 DOI: 10.1113/jphysiol.2004.069070] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2004] [Accepted: 07/26/2004] [Indexed: 12/20/2022] Open
Abstract
The common co-existence of fibromyalgia and chronic abdominal pain could be due to sensitization of spinal neurones (SNs), as a result of viscero-somatic convergence. The objective of this study is to explore the influence of acute nociceptive somatic stimulation in the form of acid injections, into the ipsilateral somatic receptive field of neurones responsive to colorectal distension (CRD), and the potential role of ionotropic glutamate receptors on sensitization. Action potentials of CRD-sensitive SNs were recorded extracellularly from the lumbar (L(2)-L(5)) spinal cord. Stimulus-response functions (SRFs) to graded CRD (10-80 mmHg, 30 s) were constructed before and 30 min after ipsilateral injection of low pH (4.0, 100 microl) saline into the somatic receptive fields. In some experiments, cervical (C(1)-C(2)) spinalization was performed to eliminate supraspinal influence. The selective NMDA receptor antagonist CGS 19755 and AMPA receptor antagonist NBQX were injected (25 micromol kg(-1), i.v.) to examine their influence on sensitization. Three types of neurones were characterized as short-latency abrupt (SLA, n = 24), short latency sustained (SLS, n = 12), and long-latency (LL, n = 6) to CRD. Ipsilateral injection of low pH (4.0) in the somatic receptive field, but not the contralateral gastrocnemius (GN) or front leg muscles, sensitized responses of these neurones to CRD. Spinalization had no influence on the development of low pH-induced sensitization. Both CGS 19755 and NBQX significantly attenuated the sensitized response to CRD in intact and spinalized animals. Acute nociceptive somatic stimulus sensitizes CRD-sensitive SNs receiving viscero-somatic convergence. The sensitization occurs at the spinal level and is independent of supraspinal influence. Ionotropic glutamate receptors in the spinal cord are involved in sensitization.
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Affiliation(s)
- Shachar Peles
- Division of Gastroenterology and Hepatology, MaccFund Research Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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Abstract
Minute-to-minute behavior of the bowel, whether it is normal or disordered, is determined by integrative functions of the enteric nervous system (ENS). Information input processed by the ENS is derived from local sensory receptors, the central nervous system, and immune/inflammatory cells including mast cells. Enteric mast cells use the power of the immune system for detection of antigenic threats and for long-term memory of the identity of the specific antigens. Specific antibodies attach to the mast cells and enable the mast cell to detect sensitizing antigens when they reappear in the gut lumen. Should the sensitizing antigen reappear, mast cells detect it and signal its presence to the ENS. The ENS interprets the mast cell signal as a threat and calls up from its program library secretory and propulsive motor behavior that is organized to eliminate the threat rapidly and effectively. Operation of the alarm program protects the individual, but at the expense of symptoms that include cramping abdominal pain, fecal urgency, and diarrhea. Enteric mast cells use immunologic memory functions to detect foreign antigens as they appear and reappear throughout the life of the individual. Mast cells use paracrine signaling for the transfer of chemical information to the neural networks of the ENS. Integrative circuits in the ENS receive and interpret the chemical signals from the mast cells. Signals from the mast cells are interpreted by the ENS as a labeled code for the presence of a threat in the intestinal lumen.
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Affiliation(s)
- Jackie D Wood
- Department of Physiology and Cell Biology and Internal Medicine, College of Medicine and Public Health, The Ohio State University, Columbus, USA.
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Honoré P, Kamp EH, Rogers SD, Gebhart GF, Mantyh PW. Activation of lamina I spinal cord neurons that express the substance P receptor in visceral nociception and hyperalgesia. THE JOURNAL OF PAIN 2003; 3:3-11. [PMID: 14622848 DOI: 10.1054/jpai.2002.27001] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Spinal lamina I neurons expressing the substance P receptor (SPR) have been shown to play a role in the transmission of somatic inflammatory and neuropathic pain. To evaluate their involvement in visceral nociception in both the noninflamed and inflamed colon, we examined the expression and ligand-induced internalization of the SPR in the rat spinal cord after distention of the noninflamed colon and in rats with inflammation induced by intracolonic instillation of zymosan (3 hours). In the noninflamed animal, acute noxious but not non-noxious colorectal distention induced SPR internalization in lamina I neurons at the thoracolumbar (T13) and lumbosacral (S1) spinal levels, whereas SPR internalization was not detected in lamina I neurons at spinal lumbar segment L4. Although zymosan-induced colorectal inflammation alone did not induce SPR internalization in lamina I neurons, there was an increased number of SPR-expressing lamina I neurons showing SPR internalization in segments T12 through S2 of the spinal cord after colorectal distention. These results show that acute noxious visceral stimuli induce activation of spinal lamina I neurons expressing the SPR and, that after visceral inflammation, there is a marked increase in both the number and rostrocaudal extent of lamina I SPR neurons activated in response to both normally non-noxious and noxious distention of the colon.
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Affiliation(s)
- Prisca Honoré
- Department of Preventive Sciences, Psychiatry and Neuroscience, University of Minnesota, Minneapolis, USA
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21
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22
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Estrogen modulates the visceromotor reflex and responses of spinal dorsal horn neurons to colorectal stimulation in the rat. J Neurosci 2003. [PMID: 12736360 DOI: 10.1523/jneurosci.23-09-03908.2003] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Many gastrointestinal pain syndromes are more prevalent in women than men, suggesting a gonadal steroid influence. We characterized the effects of estrogen on two responses to colorectal distention (CRD) in the rat: the visceromotor reflex (vmr) and L6-S1 dorsal horn neuron activity (ABRUPT and SUSTAINED neurons). Ovariectomized rats were injected with estrogen, and responses to innocuous and noxious intensities of CRD were measured between 4 hr and 14 d after injection and compared with ovariectomized and intact, cycling rats. Plasma estrogen levels were determined at each time point. Ovariectomy significantly decreased the magnitude of the vmr and ABRUPT neuron response to CRD compared with cycling rats. Four and 48 hr after estrogen injection (10 microg), the magnitude of the vmr and ABRUPT neuron response returned to the level or greater than that of cycling rats. All responses were comparable with ovariectomized rats by 7 d. These results paralleled the plasma estrogen concentration. Fifty micrograms of estrogen did not further increase the magnitude of the vmr or neuronal response 48 hr after estrogen but did extend the period of the increased ABRUPT neuron response to 14 d. Estrogen did not affect the response of SUSTAINED neurons. In a separate experiment, the response to innocuous CRD was sensitized in estrogen-treated rats but not ovariectomized or cycling rats. The present data suggest that estrogen modulates the spinal cord processing and reflex responses to innocuous and noxious colorectal stimuli in female rats and may contribute to alterations in sensory processing associated with irritable bowel syndrome.
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Greenwood-Van Meerveld B, Johnson AC, Foreman RD, Linderoth B. Attenuation by spinal cord stimulation of a nociceptive reflex generated by colorectal distention in a rat model. Auton Neurosci 2003; 104:17-24. [PMID: 12559199 DOI: 10.1016/s1566-0702(02)00262-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The mechanisms underlying the cause and treatment of visceral pain of gastrointestinal origin are poorly understood. Previous clinical studies have shown that spinal cord stimulation (SCS) attenuates neuropathic and ischemic pain, and animal experiments have provided knowledge about probable physiological mechanisms. The goal of the present study was to investigate whether SCS influences colonic sensitivity in a conscious rat. A visceromotor behavioral response (VMR), induced by colorectal distention, was used to quantify the level of colonic sensitivity. Under anesthesia, an electrode (cathode) was placed on the dorsal surface of the spinal cord at L1. One week after implantation of the SCS electrode, the effects of stimulation delivered with different intensities (50 Hz, 0.2 ms for 30 min) on colonic sensitivity were determined. Nociceptive levels of colorectal distention (60 mm Hg for 10 min) induced an enhanced VMR quantified as an increased number of abdominal muscle contractions compared to controls in which the balloon catheter was inserted into the colorectal region but not distended. Colonic sensitization with acetic acid increased the VMR to innocuous levels of colorectal distention (30 mm Hg for 10 min). We found that SCS induced a significant depression of the VMR produced by colorectal distention in both normal rats and those with sensitized colons. The suppressive effect of SCS on colonic sensitivity suggests that SCS may have therapeutic potential for the treatment of visceral pain of gastrointestinal origin associated with abdominal cramping and painful abdominal spasms.
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Affiliation(s)
- Beverley Greenwood-Van Meerveld
- Oklahoma Foundation for Digestive Research, Basic Science Laboratories, Veterans Affairs Medical Center, Research Administration Rm. 151, 921 N.E. 13th St., Oklahoma City, OK 73104, USA.
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Ji Y, Traub RJ. Differential effects of spinal CNQX on two populations of dorsal horn neurons responding to colorectal distension in the rat. Pain 2002; 99:217-22. [PMID: 12237199 DOI: 10.1016/s0304-3959(02)00106-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The present study examined the effect of a spinally administered excitatory amino acid antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 1, 2.5, 5 microg) on responses of spinal dorsal horn neurons to graded intensities (20, 40, 60, 80 mmHg) of colorectal distention (CRD). Extracellular single unit recordings were made from 28 dorsal horn neurons in the L6-S2 spinal cord. Neurons excited by CRD were subclassified as short latency abrupt (SLA) neurons and short latency sustained (SLS) neurons. The response to graded intensities of CRD was dose-dependently attenuated in 9/17 SLA neurons (53%). The response to CRD was also dose-dependently attenuated in 8/11 SLS neurons (73%). The response to CRD in the remaining eight SLA neurons and three SLS neurons was not attenuated by CNQX. Comparing only neurons that were significantly attenuated by the CNQX, it was found that the magnitude of attenuation of the response to noxious CRD (80 mmHg) produced by 5 microg CNQX was significantly greater in SLA (63 +/-6%) vs. SLS (40 +/- 6%) neurons. While CNQX produced a significant attenuation of the response to innocuous CRD (20 mmHg), there was no difference between the SLA and SLS neurons. The effects of CNQX on the response to somatic stimulation (touch, pinch) of the cutaneous receptive field of these 28 neurons were qualitatively examined in all neurons and quantitatively examined in nine neurons (five SLA and four SLS neurons). CNQX generally decreased the response to pinch or touch, even if CNQX did not attenuate the response to CRD. These results suggest that subpopulations of SLA and SLS neurons are differentially modulated by non-NMDA ionotropic excitatory amino acid receptors and that these neuronal subtypes contribute differently to visceral sensory processing. Furthermore, the lack of correlation between the effects of CNQX on visceral and somatic sensory processing in the same neuron underscores potential differences in processing of visceral and somatic pain.
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Affiliation(s)
- Yaping Ji
- Department of Oral and Craniofacial Biological Sciences, University of Maryland Dental School, 666 W Baltimore St, Baltimore, MD 21201, USA
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25
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Abstract
Widespread symptoms associated with the irritable bowel syndrome (IBS) are abnormal defecation and abdominal pain, both of which can be exacerbated by psychogenic stress. Disordered defecation may present as diarrhea or constipation. A subgroup of IBS patients alternate from one to the other over time. Urgency to stool often accompanies the diarrheal-state, and patients with the constipation-predominant form of IBS report straining and the feeling of incomplete evacuation. Basic scientific research aims for improved understanding of the physiology and pathophysiology of the digestive systems from which the arrays of IBS symptoms emerge. The key systems for the defecation-related symptoms are the intestinal secretory glands, the musculature, and the nervous system that controls and integrates their activity. Abdominal pain and discomfort arising from these systems adds the dimension of sensory neurophysiology. This review details current concepts of the underlying pathophysiology in terms of the physiology of intestinal secretion, motility, nervous control, sensing function, immuno-neural communication, and the brain-gut axis.
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Affiliation(s)
- Jackie D Wood
- Departments of Physiology and Cell Biology and Internal Medicine, Ohio State University College of Medicine and Public Health, Columbus, Ohio, USA.
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Ji Y, Traub RJ. Spinal NMDA receptors contribute to neuronal processing of acute noxious and nonnoxious colorectal stimulation in the rat. J Neurophysiol 2001; 86:1783-91. [PMID: 11600639 DOI: 10.1152/jn.2001.86.4.1783] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study investigated the role of NMDA receptors in the spinal processing of acute noxious and nonnoxious colorectal stimulation using extracellular single-unit recording in the rat. Fifty-three neurons in the L6-S2 dorsal horn of the spinal cord were studied. Neurons were identified using touch and light pinch of the ipsilateral perianal/scrotal area and colorectal distention (CRD). All neurons had excitatory responses to CRD. Thirty neurons were studied using a search stimulus of 80-mmHg CRD. The effects of a systemically administered N-methyl-D-aspartate (NMDA) receptor channel blocker, dizocilpine maleate (MK-801) (0.1, 0.5, 1.0, and 5.0 mg/kg), were tested on the CRD-evoked responses of 13 neurons. The lowest dose had no effect on the neuronal responses to CRD, while greater doses lowered the CRD-evoked responses at all distention pressures tested (20, 40, 60, and 80 mmHg). Similarly, spinal application of MK-801 (20, 50, 100, and 200 nmol) attenuated CRD-evoked activity (n = 9). In addition, a spinally administered competitive NMDA receptor antagonist, 2-amino-5-phosphonovaleric acid (APV) (30, 60, 120, and 240 nmol), dose-dependently attenuated the CRD-evoked response at all distention pressures (n = 5). Systemically administered APV did not affect neuronal responses to CRD (n = 3). Twenty-three neurons were studied in animals that never received distention pressures exceeding 30 mmHg; the search stimulus ranged between 20- and 30-mmHg CRD. These neurons were tested using 20-mmHg CRD. Systemically administered MK-801 facilitated the response to 20-mmHg CRD in three neurons and inhibited the response in five neurons, and the response of five neurons was not affected. Spinally administered MK-801 had no effect on neuronal responses to 20-mmHg CRD in six neurons. However, spinally administered APV dose-dependently decreased the response to 20-mmHg CRD in four neurons. These results are consistent with our previous observations that used Fos expression as the index, suggesting that spinal NMDA receptors contribute to processing of both noxious and nonnoxious CRD.
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Affiliation(s)
- Y Ji
- Department of Oral and Craniofacial Biological Sciences, Dental School, University of Maryland, Baltimore, Maryland 21201, USA
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27
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Andrew LK, Blackshaw LA. Colonic mechanoreceptor inputs to rat lumbo-sacral dorsal horn neurones: distribution, thresholds and chemosensory modulation. Neurogastroenterol Motil 2001; 13:333-7. [PMID: 11576392 DOI: 10.1046/j.1365-2982.2001.00272.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In order to better understand the central processing of visceral sensory information, we studied the responses of lumbo-sacral dorsal horn (L4-S1) neurones to colonic stimuli in anaesthetized rats. Twenty-four neurones responded to distal colonic distension with a 2.5-cm balloon; six of these were tested with proximal colonic distension, to which none responded. All neurones tested responded to somatic non-noxious inputs (tail movement). Responses to colonic distension were excitatory (n=22) or inhibitory (n=2). Sixteen neurones responded at a threshold of 20 mmHg or less, five at 20-40 mmHg, and three at 40-80 mmHg. Three of 10 neurones tested showed increased responses to colonic distension after intraluminal perfusion with bile. Bile itself did not evoke a response. We conclude that lumbo-sacral spinal neurones selectively receive mechanosensory inputs from the distal colon. Neurones respond at thresholds within and above the physiological range. Dorsal horn neurones receiving colonic mechanosensory inputs are not directly modulated by chemosensory inputs, but their responsiveness to distension may be augmented.
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Affiliation(s)
- L K Andrew
- Nerve-Gut Research Laboratory, Department of Gastroenterology, Hepatology and General Medicine, Royal Adelaide Hospital, Adelaide, SA, Australia
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28
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Ness TJ, Gebhart GF. Inflammation enhances reflex and spinal neuron responses to noxious visceral stimulation in rats. Am J Physiol Gastrointest Liver Physiol 2001; 280:G649-57. [PMID: 11254491 DOI: 10.1152/ajpgi.2001.280.4.g649] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To improve understanding of sensory processes related to visceral inflammation, the effect of turpentine-induced inflammation on reflex (cardiovascular/visceromotor) and extracellularly recorded lumbosacral dorsal horn neuron responses to colorectal distension (CRD) was investigated. A 25% solution of turpentine, applied to the colorectal mucosa, produced inflammation, decreased compliance of the colonic wall, and enhanced reflex responses in unanesthetized rats within 2-6 h. At 24 h posttreatment, pressor responses to CRD (80 mmHg, 20 s) were 20% greater, and intraluminal pressures needed to evoke visceromotor reflexes were 30% lower than controls. Parallel electrophysiological experiments in spinal cord-transected, decerebrate rats demonstrated that two neuronal subgroups excited by CRD were differentially affected by turpentine administered 24 h before testing. During CRD, abrupt neurons were 70% less active and sustained neurons were 25% more active than similar neurons in controls. In summary, reflex and neuronal subgroup (sustained neurons) responses to CRD were both potentiated by chemical inflammation. This suggests that the neurophysiological basis for inflammation-induced increases in reflex responses to CRD is increased activity of this neuronal subgroup.
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Affiliation(s)
- T J Ness
- Department of Anesthesiology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
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29
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Kalmari J, Niissalo S, Konttinen YT, Pertovaara A. Modulation of visceral nociceptive responses of rat spinal dorsal horn neurons by sympathectomy. Neuroreport 2001; 12:797-801. [PMID: 11277586 DOI: 10.1097/00001756-200103260-00036] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We determined whether sympathectomy modulates visceral nociception under physiological or inflammatory conditions. Recordings of sacral spinal dorsal horn neurons with sustained responses were performed in pentobarbitone-anesthetized rats. Graded colorectal distension (CRD, 20-100 mmHg) was used as a visceral nociceptive stimulus. Inflammation was induced by intracolonic instillation of turpentine (25%). Sympathectomy was produced by administering 6-hydroxydopamine. Inflammation produced an increase in the CRD-evoked responses. The CRD-evoked responses were attenuated following sympathectomy both under control and inflammatory conditions. These changes in the CRD-evoked responses were associated with corresponding changes in spontaneous discharge rate. The convergent input evoked by noxious pinch of the skin was not changed by any of the experimental conditions. The results indicate that sympathectomy attenuates visceral nociceptive responses and spontaneous activity of sacral spinal cord neurons, without effect on convergent cutaneous inputs, both under physiological and inflammatory conditions.
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Affiliation(s)
- J Kalmari
- Department of Physiology, Institute of Biomedicine, University of Helsinki, Finland
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Abstract
Visceral pain, although different from somatic pain in several important features, is not as widely researched and consequently our knowledge of neurophysiologic mechanisms as well as clinical management of visceral pain states remains unsatisfactory. Several recent studies have employed different visceral pain animal models to provide insight into the peripheral and central nervous system mechanisms underlying pain originating from the urinary bladder, ureter, and gastrointestinal tract. The effects of opioid and nonopioid drugs in these models have also been evaluated and are reviewed in this article. The importance of anatomic pathways relaying pain sensation in the central nervous system, particularly the newly described dorsal column pathway, is also discussed. In human subjects, new techniques like positron emission tomography are now being used to better understand visceral pain perception. Such findings deriving from basic animal research and human studies summarized in the present overview lead to a better understanding of visceral pain states and may be helpful in developing better treatment strategies to combat visceral pain states in the clinical setting.
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Affiliation(s)
- S K Joshi
- Department of Pharmacology, The University of Iowa College of Medicine, 2-302 Bowen Science Building, Iowa City, IA 52242, USA.
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31
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Abstract
Intestinal motility, secretion, and blood flow are controlled and integrated by the enteric nervous system (ENS). The ENS is like a "brain-in-the-gut," with many of the neurophysiologic properties of the central nervous system. Serotonin is a neurotransmitter at synapses in the microcircuits of the ENS. Serotonin is also released from enterochromaffin cells and inflammatory/immune cells to act at serotonergic receptors on neurons of the ENS. Four important actions are (1) fast and (2) slow excitation of enteric neurons, (3) presynaptic inhibition of neurotransmitter release at synapses in ENS microcircuits, and (4) excitation of intestinal sensory afferent fibers. Fast excitation and stimulation of sensory afferents are mediated by 5-HT(3) serotonergic receptors and slow excitation by 5-HT(1P) receptors. Presynaptic inhibitory receptors are not conclusively defined. The efficacy of a new 5-HT(3) receptor blocking drug in the treatment of the diarrhea-predominant form of the irritable bowel syndrome in women suggests the importance of this receptor subtype in the mediation of neurogenic secretory diarrhea, motility abnormality, and abdominal pain and discomfort.
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Affiliation(s)
- J D Wood
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine and Public Health, Columbus, Ohio 43210, USA.
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32
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Abstract
Visceral pain is of great concern to the medical community because it remains particularly resistant to current clinical treatments. A serendipitous and initially unexplainable clinical finding that a punctate midline dorsal column lesion is effective in eliminating visceral pain, however, has initiated a resurgence of interest in the study of the basic mechanisms of visceral nociception. Clinical and anatomic findings have determined that visceral pain either of thoracic or pelvic origin can be relieved by carefully placed lesions directed at the lateral edge or the medial edge of the gracile fasciculus, respectively. Studies are demonstrating that visceral pain is quite unique from cutaneous pain.
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Affiliation(s)
- K N Westlund
- Department of Anatomy and Neurosciences, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
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