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Robbins MT, DeWitte C, Ness TJ. Stress-induced bladder hypersensitivity: Effect of corticotropin releasing factor receptors assessed by spinal neurophysiology and neurochemistry. Neuropharmacology 2023; 224:109369. [PMID: 36493859 PMCID: PMC9790032 DOI: 10.1016/j.neuropharm.2022.109369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 11/09/2022] [Accepted: 12/03/2022] [Indexed: 12/12/2022]
Abstract
Corticotropin releasing factor (CRF) receptors have been implicated in stress-induced hyperalgesia. The present study examined the role of CRF receptors Type 1&2 (CRFR1, CRFR2) in stress-induced bladder hyperalgesia in female rats by quantifying changes in receptor and agonist content following chronic (CFS, 7 daily episodes), acute (AFS, single episode) and control (NFS, no episodes) footshock protocols. ELISAs demonstrated that CFS lead to an increase in spinal thoracolumbar and lumbosacral spinal cord CRFR2 content and a decrease in lumbosacral spinal cord CRFR1 content. Content of the endogenous CRFR2 agonist, urocortin 2, was also increased in lumbosacral spinal cord and bladder tissues of CFS-pretreated rats, but urocortin 3 was decreased. Correlative single unit studies of lumbosacral dorsal horn neurons excited by bladder distension, in anesthetized rats that had undergone CFS, AFS or NFS protocols, used a before-after methodology with administration of a CRFR1 antagonist (antalarmin, 24 μg), CRFR2 antagonist (aSVG30, 12 μg) or normal saline topically to the exposed spinal cord following primary characterization. aSVG30 produced a reduction of neuronal responses evoked by bladder distension in CFS-pretreated rats but no statistically significant effects of aSVG30, antalarmin or vehicle were noted in other groups tested with the exception that antalarmin had an inhibitory effect on spontaneous activity in NFS-pretreated rats. The present findings are consistent with previous experiments using reflex responses to bladder distension as endpoints and further support a role for CRFR2-related mechanisms in stress-induced bladder hypersensitivity. This suggests CRFR2 antagonists may have efficacy in the treatment of bladder pain.
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Affiliation(s)
- Meredith T Robbins
- University of Alabama at Birmingham, Department of Anesthesiolology and Perioperative Medicine, Birmingham, AL, 35205, USA
| | - Cary DeWitte
- University of Alabama at Birmingham, Department of Anesthesiolology and Perioperative Medicine, Birmingham, AL, 35205, USA
| | - Timothy J Ness
- University of Alabama at Birmingham, Department of Anesthesiolology and Perioperative Medicine, Birmingham, AL, 35205, USA.
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Neonatal cystitis alters mechanisms of stress-induced visceral hypersensitivity in rats. Neurosci Lett 2022; 778:136617. [PMID: 35390467 PMCID: PMC9018594 DOI: 10.1016/j.neulet.2022.136617] [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: 02/02/2022] [Revised: 03/15/2022] [Accepted: 04/01/2022] [Indexed: 11/21/2022]
Abstract
In rodent models, conditioning with acute footshock (AFS) has been demonstrated to produce bladder hypersensitivity which is more robust when rats, tested as adults, had also been pretreated with neonatal bladder inflammation (NBI). The spinal neurochemical mechanisms of pro-nociceptive processes in rats pretreated with NBI are not fully known and so the present study administered intrathecal (IT) opioid (naloxone) and NMDA receptor (MK-801) antagonists to determine whether these receptors' actions had been altered by NBI. Female Sprague-Dawley rat pups were intravesically pretreated on postnatal days P14-P16 with a 1% zymosan solution or with control procedures and then raised to adulthood (12-15 weeks of age). Bladder hypersensitivity was induced through use of an AFS paradigm. Visceromotor responses (VMRs; abdominal muscle contractions) to graded, air pressure-controlled urinary bladder distension were used as nociceptive endpoints. Immediately following AFS pretreatments, rats were anesthetized and surgically prepared. Pharmacological antagonists were administered via an IT catheter onto the lumbosacral spinal cord and VMRs determined 15 min later. Administration of IT naloxone hydrochloride (10 μg) to rats which had been pretreated only with AFS resulted in VMRs that were more robust than VMRs in similarly pretreated rats that received IT normal saline. In contrast, IT naloxone had no significant effect on rats that had been pretreated with both NBI&AFS, although MK-801 was inhibitory. These effects of IT naloxone suggest the presence of inhibitory influences in normal rats that are absent in rats pretreated with NBI. Absence of inhibitory influences produced by AFS was also demonstrated in rats pretreated with NBI&AFS using measures of thermal paw withdrawal latency (PWL): rats pretreated with only AFS had longer PWLs than rats pretreated with both NBI&AFS. Together, a reduction in anti-nociceptive mechanisms coupled with pro-nociceptive NMDA-linked mechanisms results in more robust nociceptive responses to distension in rats which had experienced NBI.
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Gao Y, Rodríguez LV. The Effect of Chronic Psychological Stress on Lower Urinary Tract Function: An Animal Model Perspective. Front Physiol 2022; 13:818993. [PMID: 35388285 PMCID: PMC8978557 DOI: 10.3389/fphys.2022.818993] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 02/18/2022] [Indexed: 12/12/2022] Open
Abstract
Chronic psychological stress can affect urinary function and exacerbate lower urinary tract (LUT) dysfunction (LUTD), particularly in patients with overactive bladder (OAB) or interstitial cystitis–bladder pain syndrome (IC/BPS). An increasing amount of evidence has highlighted the close relationship between chronic stress and LUTD, while the exact mechanisms underlying it remain unknown. The application of stress-related animal models has provided powerful tools to explore the effect of chronic stress on LUT function. We systematically reviewed recent findings and identified stress-related animal models. Among them, the most widely used was water avoidance stress (WAS), followed by social stress, early life stress (ELS), repeated variable stress (RVS), chronic variable stress (CVS), intermittent restraint stress (IRS), and others. Different types of chronic stress condition the induction of relatively distinguished changes at multiple levels of the micturition pathway. The voiding phenotypes, underlying mechanisms, and possible treatments of stress-induced LUTD were discussed together. The advantages and disadvantages of each stress-related animal model were also summarized to determine the better choice. Through the present review, we hope to expand the current knowledge of the pathophysiological basis of stress-induced LUTD and inspire robust therapies with better outcomes.
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Affiliation(s)
- Yunliang Gao
- Department of Urology, The Second Xiangya Hospital of Central South University, Changsha, China
| | - Larissa V. Rodríguez
- Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- *Correspondence: Larissa V. Rodríguez,
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Ness TJ, DeWitte C, DeBerry JJ. Spinal neurochemical mechanisms of acute stress-induced visceral hypersensitivity in healthy rats. Neurosci Lett 2022; 770:136401. [PMID: 34929317 PMCID: PMC8810671 DOI: 10.1016/j.neulet.2021.136401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 12/11/2021] [Accepted: 12/13/2021] [Indexed: 01/25/2023]
Abstract
Psychological stress has been demonstrated to increase reports of pain in humans with pelvic pain of urologic origin. In rodent models, conditioning with acute footshock (AFS) has been demonstrated to increase measures of stress/anxiety as well as bladder hypersensitivity. The spinal neurochemical mechanisms of this pro-nociceptive process are unknown and so the present study administered antagonists for multiple receptors that have been associated with facilitatory mechanisms into the spinal intrathecal space. Bladder hypersensitivity was induced through use of an AFS paradigm in which female Sprague-Dawley rats received a 15-min intermittent shock treatment. Visceromotor responses (VMRs; abdominal muscle contractions) to air pressure-controlled urinary bladder distension (UBD) were used as nociceptive endpoints. Immediately following AFS treatments, rats were anesthetized (inhaled isoflurane, IP urethane) and surgically prepared. Pharmacological antagonists were administered via an intrathecal (IT) catheter onto the lumbosacral spinal cord and VMRs to graded UBD determined 15 min later. Administration of IT naloxone hydrochloride (10 μg) and IT phentolamine hydrochloride (10 μg) resulted in VMRs that were more robust than VMRs in rats that received AFS and IT normal saline whereas there was no significant effect of these drugs on VMRs in rats which underwent non-footshock procedures. In contrast, a low dose of the NMDA-receptor antagonist, MK-801 (30 μg), significantly reduced VMRs in rats made hypersensitive to UBD by AFS, but had no significant effect on rats that underwent non-footshock procedures. This study suggests that pro-nociceptive effects of AFS in otherwise healthy rats involve a spinal NMDA-linked mechanism. The effects of IT naloxone and IT phentolamine suggest the presence of inhibitory influences that are opioidergic and/or alpha-adrenergic and that are masked by the pro-nociceptive mechanisms. Other agents with no statistically significant effect on VMRs include methysergide (30 μg), ondansetron (10 μg), mecamylamine (50 μg), antalarmin (24 μg), aSVG30 (12 μg), and SSR149415 (50 μg).
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Affiliation(s)
- Timothy J Ness
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, United States.
| | - Cary DeWitte
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, United States.
| | - Jennifer J DeBerry
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, United States.
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Ness TJ, DeWitte C, DeBerry JJ, Randich A. Neonatal bladder inflammation alters the role of the central amygdala in hypersensitivity produced by Acute Footshock stress in adult female rats. Brain Res 2018; 1698:99-105. [PMID: 29964025 DOI: 10.1016/j.brainres.2018.06.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 05/26/2018] [Accepted: 06/28/2018] [Indexed: 01/11/2023]
Abstract
There is increasing evidence that chronic pain may be associated with events that occur during critical periods of development. Recent studies have identified behavioral, spinal neurophysiological and spinal/peripheral neurochemical differences in rats that have experienced neonatal bladder inflammation (NBI): a putative model of the chronically painful bladder disorder, interstitial cystitis. Stress has been shown to exacerbate symptoms of interstitial cystitis and produces bladder hypersensitivity in animal models. We recently reported that Acute Footshock-induced bladder hypersensitivity was eliminated in otherwise normal rats by prior bilateral lesions of the central nucleus of the amygdala. Since the spinal and peripheral nervous systems of NBI-treated rats are known to differ from normal rats, the present experiments sought to determine whether a supraspinal nervous system structure, the central amygdala, is still necessary for the induction of Acute Footshock-induced hypersensitivity. The effect of bilateral amygdala electrolytic lesions on Acute Footshock-induced bladder hypersensitivity in adult female rats was tested in Control rats which underwent a control protocol as neonates and in experimental rats which experienced NBI. Consistent with our previous report, in Control rats, Acute Footshock-induced bladder hypersensitivity was eliminated by bilateral Amygdala Lesions. In contrast, Acute Footshock-induced bladder hypersensitivity in NBI-treated rats was unaffected by bilateral Amygdala Lesions. These findings provide evidence that NBI results in the recruitment of substrates of bladder hypersensitivity that may differ from those of normal rats. This, in turn, suggests that unique therapeutics may be needed for painful bladder disorders like interstitial cystitis.
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Affiliation(s)
- Timothy J Ness
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
| | - Cary DeWitte
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Jennifer J DeBerry
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Alan Randich
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
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Randich A, DeWitte C, DeBerry JJ, Robbins MT, Ness TJ. Lesions of the central amygdala and ventromedial medulla reduce bladder hypersensitivity produced by acute but not chronic foot shock. Brain Res 2017; 1675:1-7. [PMID: 28867481 DOI: 10.1016/j.brainres.2017.08.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Revised: 08/11/2017] [Accepted: 08/28/2017] [Indexed: 02/07/2023]
Abstract
Both acute and chronic stress has been shown to exacerbate symptoms of chronic visceral pain conditions such as interstitial cystitis. Studies using animal models support these findings in that both acute and chronic exposure to foot shock-induced stress (FS) augment nociceptive reflex responses to urinary bladder distension (UBD). Only a few studies have examined the neural substrates mediating these phenomena and it is not clear whether acute and chronic stress engage the same or different substrates to produce bladder hypersensitivity. The present studies examined the role of two important central nervous system structures - the amygdala (AMG) and the ventromedial medulla (VMM) - in mediating/modulating hypersensitivity evoked by acute versus chronic FS using responses to graded UBD in adult, female Sprague-Dawley rats. Bladder hypersensitivity produced by acute FS was significantly reduced by either bilateral central AMG or VMM lesions using measures generated by graded UBD, but these lesions had no significant effects using the same measures on bladder hyperalgesia produced by chronic FS. Our findings provide evidence that neural substrates underlying bladder hypersensitivity produced by chronic stress differ from those produced by acute stress. These findings suggest that while the AMG and VMM participate in pain processing during periods of limited exposure to stress, prolonged stress may recruit a new set of neural substrates not initially activated by acute exposure to stress.
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Affiliation(s)
- Alan Randich
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Cary DeWitte
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jennifer J DeBerry
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Meredith T Robbins
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Timothy J Ness
- Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States.
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Long CC, Sadler KE, Kolber BJ. Hormonal and molecular effects of restraint stress on formalin-induced pain-like behavior in male and female mice. Physiol Behav 2016; 165:278-85. [PMID: 27520589 PMCID: PMC5028300 DOI: 10.1016/j.physbeh.2016.08.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 07/15/2016] [Accepted: 08/08/2016] [Indexed: 12/27/2022]
Abstract
The evolutionary advantages to the suppression of pain during a stressful event (stress-induced analgesia (SIA)) are obvious, yet the reasoning behind sex-differences in the expression of this pain reduction are not. The different ways in which males and females integrate physiological stress responses and descending pain inhibition are unclear. A potential supraspinal modulator of stress-induced analgesia is the central nucleus of the amygdala (CeA). This limbic brain region is involved in both the processing of stress and pain; the CeA is anatomically and molecularly linked to regions of the hypothalamic pituitary adrenal (HPA) axis and descending pain network. The CeA exhibits sex-based differences in response to stress and pain that may differentially induce SIA in males and females. Here, sex-based differences in behavioral and molecular indices of SIA were examined following noxious stimulation. Acute restraint stress in male and female mice was performed prior to intraplantar injections of formalin, a noxious inflammatory agent. Spontaneous pain-like behaviors were measured for 60min following formalin injection and mechanical hypersensitivity was evaluated 120 and 180min post-injection. Restraint stress altered formalin-induced spontaneous behaviors in male and female mice and formalin-induced mechanical hypersensitivity in male mice. To assess molecular indices of SIA, tissue samples from the CeA and blood samples were collected at the 180min time point. Restraint stress prevented formalin-induced increases in extracellular signal regulated kinase 2 (ERK2) phosphorylation in the male CeA, but no changes associated with pERK2 were seen with formalin or restraint in females. Sex differences were also seen in plasma corticosterone concentrations 180min post injection. These results demonstrate sex-based differences in behavioral, molecular, and hormonal indices of acute stress in mice that extend for 180min after stress and noxious stimulation.
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Affiliation(s)
- Caela C Long
- Biology Department, Swarthmore College, Swarthmore, PA 19081, United States; Department of Biological Sciences and Chronic Pain Research Consortium, Duquesne University, Pittsburgh, PA 15219, United States
| | - Katelyn E Sadler
- Department of Biological Sciences and Chronic Pain Research Consortium, Duquesne University, Pittsburgh, PA 15219, United States
| | - Benedict J Kolber
- Department of Biological Sciences and Chronic Pain Research Consortium, Duquesne University, Pittsburgh, PA 15219, United States.
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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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DeBerry JJ, Robbins MT, Ness TJ. The amygdala central nucleus is required for acute stress-induced bladder hyperalgesia in a rat visceral pain model. Brain Res 2015; 1606:77-85. [PMID: 25698616 DOI: 10.1016/j.brainres.2015.01.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 12/29/2014] [Accepted: 01/07/2015] [Indexed: 11/30/2022]
Abstract
Chronic stress has been implicated in the pathogenesis of chronic visceral pain conditions, such as interstitial cystitis (IC), and bouts of acute stress exacerbate clinical urological pain. Studies using animal models have shown that exposure to chronic footshock stress augments reflex responses to urinary bladder distension (UBD) in animal models, however acute effects in animal models are largely unknown, as are the central nervous system mechanisms of stress-related increases in nociception. The amygdala is a salient structure for integration of sensory and cognitive/emotional factors. The present study determined the role of the central nucleus of the amygdala (CeA) in stress-related bladder hypersensitivity. We examined the effects of CeA manipulations (lesions and chemical stimulation) on visceromotor responses (abdominal muscle contractions) to UBD in adult, female Sprague-Dawley rats. We report that acute footshock stress produces bladder hyperalgesia that can be prevented by bilateral CeA lesions, despite no effect of lesions on baseline somatic sensation, as indicated by flinch/jump thresholds to electrical shock. Further, acute glucocorticoid stimulation of the CeA recapitulated stress-induced hyperalgesia. Of note is that CeA lesions, but not chemical stimulation, significantly affected HPA axis activation, as indicated by measurements of circulating corticosterone. Our findings conclusively show that the CeA is necessary for the generation of bladder hyperalgesia in response to acute stress. The CeA may play multiple stress-related roles in nociceptive modulation, i.e., via direct facilitation of the HPA axis during acute stress, or via modulation of other systems that augment acute stress responsiveness.
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Affiliation(s)
- Jennifer J DeBerry
- Department of Anesthesiology, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, USA.
| | - Meredith T Robbins
- Department of Anesthesiology, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Timothy J Ness
- Department of Anesthesiology, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Psychology, University of Alabama at Birmingham, Birmingham, AL, USA
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Abstract
SUMMARY The treatment of chronic pelvic pain in both females and males is a challenge for pain clinicians. Standard therapies are multimodal in nature with use of behavioral, medical and procedural therapeutics. In recent years, our understanding of the neurobiology of this disorder has improved and novel approaches have focused on neuromodulatory options, novel pharmacology and complementary/alternative medicine options. This review briefly examines newly employed therapeutic options, while restating currently utilized options. The current state-of-the-art treatment includes focal therapies for identified pathologies and empiric trials of other options for care when precise sources of the chronic pelvic pain are ill defined.
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Affiliation(s)
- Mercy A Udoji
- Department of Anesthesiology, University of Alabama at Birmingham, AL, USA
| | - Timothy J Ness
- Department of Anesthesiology, University of Alabama at Birmingham, AL, USA
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He YQ, Chen Q, Ji L, Wang ZG, Bai ZH, Stephens RL, Yang M. PKCγ receptor mediates visceral nociception and hyperalgesia following exposure to PTSD-like stress in the spinal cord of rats. Mol Pain 2013; 9:35. [PMID: 23837410 PMCID: PMC3751645 DOI: 10.1186/1744-8069-9-35] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 07/04/2013] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Clinical studies indicate that patients with post-traumatic stress disorder (PTSD) frequently share comorbidity with numerous chronic pain conditions. However, the sustained effects of PTSD-like stress over time on visceral nociception and hyperalgesia have been rarely studied, and the underlying mechanisms of stress-induced modulation of visceral hyperalgesia remain elusive. The purpose of this study was to investigate the characterization of visceral nociception and hyperalgesia over time in rats exposed to PTSD-like stress, and to explore the potential role of protein kinase C gamma (PKCγ) in mediating visceral hyperalgesia following exposure to PTSD-like stress. RESULTS On day 1, the rats exposed to single-prolonged stress (SPS, an established animal model for PTSD) exhibited an analgesic response and its visceromotor response (VMR) to graded colorectal distention (CRD) at 40 and 60 mmHg was reduced compared with the control group (all P < 0.05). On day 6, the VMR returned to the baseline value. However, as early as 7 days after SPS, VMR dramatically increased compared with its baseline value and that in the controls (all P < 0.001) and this increase persisted for 28 days, with the peak on day 9. Abdominal withdrawal reflex (AWR) scores were higher in SPS rats than in controls on days 7, 9, 14, 21 and 28 (all P < 0.001). Intrathecal administration of GF109203X (an inhibitor of PKC gamma), attenuated the SPS-induced increase in both VMR and AWR scores on days 7, 14, 21 and 28 (all P < 0.05). PKCγ protein expression determined by immunofluorescence was reduced in the spinal cord within 3 days after the exposure to SPS (P < 0.01), which returned to normal levels between days 4 and 6, and significantly increased from day 7, and this increase was maintained on days 14, 21, and 28 (all P < 0.001), with the peak on day 9. In addition, Western blotting showed a consistent trend in the changes of PKCγ protein expression. CONCLUSIONS The modified SPS alters visceral sensitivity to CRD, and contributes to the maintenance of visceral hyperalgesia, which is associated with enhanced PKCγ expression in the spinal cord. Functional blockade of the PKCγ receptors attenuates SPS-induced visceral hyperalgesia. Thus, the present study identifies a specific molecular mechanism for visceral hyperalgesia which may pave the way for novel therapeutic strategies for PTSD-like conditions.
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Shaffer AD, Ball CL, Robbins MT, Ness TJ, Randich A. Effects of acute adult and early-in-life bladder inflammation on bladder neuropeptides in adult female rats. BMC Urol 2011; 11:18. [PMID: 21843346 PMCID: PMC3171712 DOI: 10.1186/1471-2490-11-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Accepted: 08/15/2011] [Indexed: 12/26/2022] Open
Abstract
Background The purpose of the present study was to determine how acute adult and/or prior early-in life (EIL; P14-P16) exposure to bladder inflammation affects bladder content of calcitonin gene related peptide (CGRP) and substance P (SP). Estrous cycle influences were also studied in the adult-treatment conditions. Methods In Experiment 1, intravesical zymosan or isoflurane anesthesia alone was administered to adult female rats. Bladders and serum were collected 24 hours later during each phase of the estrous cycle. In Experiment 2, zymosan or anesthesia alone was administered EIL and as adults, with bladder tissue collection 24 h later. Results In general, Experiment 1 showed that bladder content of both CGRP and SP was increased by inflammation. This effect was significant when data were collapsed across all phases of the estrous cycle, but was only significant during proestrus when individual comparisons were made during each phase of estrous. Also, adult bladder inflammation significantly reduced estradiol levels. In Experiment 2, bladder content of CGRP and SP was significantly increased in rats receiving EIL and/or adult inflammation. Bladder weights were also significantly increased by inflammation. Conclusions These data indicate that bladder CGRP and SP are maximally increased during the proestrus phase of the estrous cycle in inflamed adult female rats. EIL exposure to bladder inflammation alone can also produce an increase in CGRP and SP lasting into adulthood. Therefore, EIL experience with bladder inflammation may predispose an organism to experience a painful bladder disorder as an adult by increasing primary afferent content of CGRP and/or SP.
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Affiliation(s)
- Amber D Shaffer
- Department of Psychology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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