Cross-organ interactions between reproductive, gastrointestinal, and urinary tracts: modulation by estrous stage and involvement of the hypogastric nerve

Antinociceptive Effects of an Anti-CGRP Antibody in Rat Models of Colon-Bladder Cross-Organ Sensitization

Irritable bowel syndrome (IBS) and bladder pain syndrome/interstitial cystitis (BPS/IC) are comorbid visceral pain disorders seen commonly in women with unknown etiology and limited treatment options and can involve visceral organ cross-sensitization. Calcitonin gene-related peptide (CGRP) is a mediator of nociceptive processing and may serve as a target for therapy. In three rodent models, we employed a monoclonal anti-CGRP F(ab')2 to investigate the hypothesis that visceral organ cross-sensitization is mediated by abnormal CGRP signaling. Visceral organ cross-sensitization was induced in adult female rats via transurethral infusion of protamine sulfate (PS) into the urinary bladder or infusion into the colon of trinitrobenzene sulfonic acid (TNBS). Colonic sensitivity was assessed via the visceromotor response to colorectal distension (CRD). Bladder sensitivity was assessed as the frequency of abdominal withdrawal reflexes to von Frey filaments applied to the suprapubic region. PS- or TNBS-induced changes in colonic and bladder permeability were investigated in vitro via quantification of transepithelial electrical resistance (TEER). Peripheral administration of an anti-CGRP F(ab')2 inhibited PS-induced visceral pain behaviors and colon hyperpermeability. Similarly, TNBS-induced pain behaviors and colon and bladder hyperpermeability were attenuated by anti-CGRP F(ab')2 treatment. PS into the bladder or TNBS into the colon significantly increased the visceromotor response to CRD and abdominal withdrawal reflexes to suprapubic stimulation and decreased bladder and colon TEER. These findings suggest an important role of peripheral CGRP in visceral nociception and organ cross-sensitization and support the evaluation of CGRP as a therapeutic target for visceral pain in patients with IBS and/or BPS/IC. SIGNIFICANCE STATEMENT: A monoclonal antibody against calcitonin gene-related peptide (CGRP) was found to reduce concomitant colonic and bladder hypersensitivity and hyperpermeability. The results of this study suggest that CGRP-targeting antibodies, in addition to migraine prevention, may provide a novel treatment strategy for multiorgan abdominopelvic pain following injury or inflammation.

Bladder Pain Sensitivity Is a Potential Risk Factor for Irritable Bowel Syndrome

BACKGROUND

Although dysmenorrhea is a highly prevalent risk factor for irritable bowel syndrome (IBS), the factors underlying this risk are not fully understood. Prior studies support a hypothesis that repeated distressing menstrual pain promotes cross-organ pelvic sensitization with heightened visceral sensitivity.

AIMS

To further explore cross-organ pelvic sensitization we examined the association of dysmenorrhea, provoked bladder pain, and other putative factors with self-reported IBS-domain pain frequency and new onset after 1-year follow up.

METHODS

We measured visceral pain sensitivity with a noninvasive provoked bladder pain test in a cohort of reproductive-aged women, enriched for those reporting moderate-to-severe menstrual pain intensity but without any prior IBS diagnosis (n = 190). We analyzed the relationship between menstrual pain, provoked bladder pain, pain catastrophizing, anxiety, and depression with primary outcomes: (1) frequency of self-reported IBS-domain pain and (2) new onset of IBS-domain pain after 1-year follow up.

RESULTS

All hypothesized factors correlated with the frequency of IBS-domain pain (p's ≤ 0.038). In a cross-sectional model, only menstrual pain (standardized adjusted odds ratio 2.07), provoked bladder pain (1.49), and anxiety (1.90) were independently associated with IBS-domain pain ≥ 2 days/month (C statistic = 0.79). One year later, provoked bladder pain (3.12) was the only significant predictor of new onset IBS-domain pain (C statistic = 0.87).

CONCLUSION

Increased visceral sensitivity among women with dysmenorrhea could lead to IBS. Because provoked bladder pain predicted subsequent IBS, prospective studies should be performed to see if the early treatment of visceral hypersensitivity mitigates IBS.

Secondary Dysfunction of the Intestinal Barrier in the Pathogenesis of Complications of Acute Poisoning

The last decade has been marked by an exponential increase in the number of publications on the physiological role of the normal human gut microbiota. The idea of a symbiotic relationship between the human organism and normal microbiota of its gastrointestinal tract has been firmly established as an integral part of the current biomedical paradigm. However, the type of this symbiosis varies from mutualism to parasitism and depends on the functional state of the host organism. Damage caused to the organism by external agents can lead to the emergence of conditionally pathogenic properties in the normal gut microbiota, mediated by humoral factors and affecting the outcome of exogenous exposure. Among the substances produced by symbiotic microbiota, there are an indefinite number of compounds with systemic toxicity. Some occur in the intestinal chyme in potentially lethal amounts in the case they enter the bloodstream quickly. The quick entry of potential toxicants is prevented by the intestinal barrier (IB), a set of structural elements separating the intestinal chyme from the blood. Hypothetically, severe damage to the IB caused by exogenous toxicants can trigger a leakage and subsequent systemic redistribution of toxic substances of bacterial origin. Until recently, the impact of such a redistribution on the outcome of acute exogenous poisoning remained outside the view of toxicology. The present review addresses causal relationships between the secondary dysfunction of the IB and complications of acute poisoning. We characterize acute systemic toxicity of such waste products of the normal gut microflora as ammonia and endotoxins, and demonstrate their involvement in the formation of such complications of acute poisoning as shock, sepsis, cerebral insufficiency and secondary lung injuries. The principles of assessing the functional state of the IB and the approaches to its protection in acute poisoning are briefly considered.

Intestinal Permeability and Dysbiosis in Female Patients with Recurrent Cystitis: A Pilot Study

Recurrent cystitis (RC) is a common disease, especially in females. Anatomical, behavioral and genetic predisposing factors are associated with the ascending retrograde route, which often causes bladder infections. RC seems to be mainly caused by agents derived from the intestinal microbiota, and most frequently by Escherichia coli. Intestinal contiguity contributes to the etiopathogenesis of RC and an alteration in intestinal permeability could have a major role in RC. The aim of this pilot study is to assess gut microbiome dysbiosis and intestinal permeability in female patients with RC. Patients with RC (n = 16) were enrolled and compared with healthy female subjects (n = 15) and patients with chronic gastrointestinal (GI) disorders (n = 238). We calculated the Acute Cystitis Symptom Score/Urinary Tract Infection Symptom Assessment (ACSS/UTISA) and Gastrointestinal Symptom Rating Scale (GSRS) scores and evaluated intestinal permeability and the fecal microbiome in the first two cohorts. Patients with RC showed an increased prevalence of gastrointestinal symptoms compared with healthy controls. Of the patients with RC, 88% showed an increased intestinal permeability with reduced biodiversity of gut microbiota compared to healthy controls, and 68% of the RC patients had a final diagnosis of gastrointestinal disease. Similarly, GI patients reported a higher incidence of urinary symptoms with a diagnosis of RC in 20%. Gut barrier impairment seems to play a major role in the pathogenesis of RC. Further studies are necessary to elucidate the role of microbiota and intestinal permeability in urinary tract infections.

Identification and characterization of rostral ventromedial medulla neurons synaptically connected to the urinary bladder afferents in female rats with or without neonatal cystitis

The neurons in the rostral ventromedial medulla (RVM) play a major role in pain modulation. We have previously shown that early-life noxious bladder stimuli in rats resulted in an overall spinal GABAergic disinhibition and a long-lasting bladder/colon sensitization when tested in adulthood. However, the neuromolecular alterations within RVM neurons in the pathophysiology of early life bladder inflammation have not been elucidated. In this study, we have identified and characterized RVM neurons that are synaptically linked to the bladder and colon and examined the effect of neonatal bladder inflammation on molecular expressions of these neurons. A transient bladder inflammation was induced by intravesicular instillation of protamine sulfate and zymosan during postnatal days 14 through 16 (P14-16) followed by pseudorabies virus PRV-152 and PRV-614 injections into the bladder and colon, respectively, on postnatal day P60. Tissues were examined 96 h postinoculation for serotonergic, GABAergic, and enkephalinergic expressions using in situ hybridization and/or immunohistochemistry techniques. The results revealed that > 50% of RVM neurons that are synaptically connected to the bladder (i.e., PRV-152+) were GABAergic, 40% enkephalinergic, and about 14% expressing serotonergic marker tryptophan hydroxylase 2 (TpH2). Neonatal cystitis resulted in a significant increase in converging neurons in RVM receiving dual synaptic inputs from the bladder and colon. In addition, neonatal cystitis significantly downregulated vesicular GABA transporter (VGAT) with a concomitant increase in TpH2 expression in bladder-linked RVM neurons, suggesting an alteration in supraspinal signaling. These alterations of synaptic connectivity and GABAergic/serotonergic expressions in RVM neurons may contribute to bladder pain modulation and cross-organ visceral sensitivity.

Pharmacological modulation of voltage-gated sodium (NaV) channels alters nociception arising from the female reproductive tract

Dyspareunia, also known as vaginal hyperalgesia, is a prevalent and debilitating symptom of gynaecological disorders such as endometriosis and vulvodynia. Despite this, the sensory pathways transmitting nociceptive information from female reproductive organs remain poorly characterised. As such, the development of specific treatments for pain associated with dyspareunia is currently lacking. Here, we examined, for the first time, (1) the mechanosensory properties of pelvic afferent nerves innervating the mouse vagina; (2) the expression profile of voltage-gated sodium (NaV) channels within these afferents; and (3) how pharmacological modulation of these channels alters vaginal nociceptive signalling ex vivo, in vitro, and in vivo. We developed a novel afferent recording preparation and characterised responses of pelvic afferents innervating the mouse vagina to different mechanical stimuli. Single-cell reverse transcription-polymerase chain reaction determined mRNA expression of NaV channels within vagina-innervating dorsal root ganglia neurons. Vagina-innervating dorsal root ganglia neuroexcitability was measured using whole-cell patch-clamp electrophysiology. Nociception evoked by vaginal distension was assessed by dorsal horn neuron activation within the spinal cord and quantification of visceromotor responses. We found that pelvic afferents innervating the vagina are tuned to detect various mechanical stimuli, with NaV channels abundantly expressed within these neurons. Pharmacological modulation of NaV channels (with veratridine or tetrodotoxin) correspondingly alters the excitability and mechanosensitivity of vagina-innervating afferents, as well as dorsal horn neuron activation and visceromotor responses evoked by vaginal distension. This study identifies potential molecular targets that can be used to modulate vaginal nociceptive signalling and aid in the development of approaches to manage endometriosis and vulvodynia-related dyspareunia.

Pain in Endometriosis

Endometriosis is a chronic and debilitating condition affecting ∼10% of women. Endometriosis is characterized by infertility and chronic pelvic pain, yet treatment options remain limited. In many respects this is related to an underlying lack of knowledge of the etiology and mechanisms contributing to endometriosis-induced pain. Whilst many studies focus on retrograde menstruation, and the formation and development of lesions in the pathogenesis of endometriosis, the mechanisms underlying the associated pain remain poorly described. Here we review the recent clinical and experimental evidence of the mechanisms contributing to chronic pain in endometriosis. This includes the roles of inflammation, neurogenic inflammation, neuroangiogenesis, peripheral sensitization and central sensitization. As endometriosis patients are also known to have co-morbidities such as irritable bowel syndrome and overactive bladder syndrome, we highlight how common nerve pathways innervating the colon, bladder and female reproductive tract can contribute to co-morbidity via cross-organ sensitization.

Pelvic Floor Nonrelaxation: Approach to Evaluation and Treatment

Dyssynergic defecation can be a complex, burdensome condition. A multidisciplinary approach to these patients is often indicated based on concomitant pathology or symptomatology across the pelvic organs. Escalating treatment options should be based on shared decision making and include medical and lifestyle optimization, pelvic floor physical therapy with biofeedback, Botox injection, sacral neuromodulation, rectal irrigation, and surgical diversion.

Bladder-bowel interactions: Do we understand pelvic organ cross-sensitization? International Consultation on Incontinence Research Society (ICI-RS) 2018

AIMS

Mounting evidence from experimental animal and human studies suggests that cross-sensitization exists between different organs. Lower urinary tract (LUT) and bowel dysfunction commonly overlap, and the role of cross-sensitization between pelvic visceral organs is uncertain.

METHODS

At the International Consultation on Incontinence Research Society (ICI-RS) meeting in 2018, a panel of clinicians participated in a discussion on bladder and bowel interactions in the context of pelvic organ cross-sensitization.

RESULTS

Bladder and bowel problems commonly co-occur in adults and children across different disorders, and the mechanism responsible for overlapping dysfunction is uncertain in most instances. At a neuronal level, cross-sensitization occurs as a result of afferent signaling from the LUT and lower bowel through different central and peripheral mechanisms. Studies in animals and humans have demonstrated evidence for cross-organ sensitization following experimental inflammation or distension of the lower bowel, affecting the LUT. Nerve stimulation is an effective treatment for different functional LUT and bowel disorders, and whether this treatment may influence cross-organ sensitization remains uncertain. The role of physiologically dormant C-fibers, the bladder-gut-brain axis, and gut microbiome in cross-sensitization are speculative.

CONCLUSION

Recommendations for research were made to explore the role of cross-organ sensitization in the pathogenesis of co-occurring LUT and bowel dysfunction in humans.

Influence of Sleeping Patterns in Health and Academic Performance Among University Students

Sleep problems in university students are important and have implications for health, quality of life, and academic performance. Using an ex post facto design, a total sample of 855 students (55.7% women) participated in the study. Sleep assessment was conducted using the Pittsburgh Sleep Quality Index, the Nightmare Frequency Scale, the Nightmare Proneness Scale, and the Composite Morningness Scale. Women show a higher risk [OR = 2.61] of presenting poor sleep quality (> 5 points on the PSQI) compared with men (p < 0.001). Similarly, women reported a greater frequency of nightmares (p < 0.001, d = 0.60), greater propensity for nightmares (p < 0.001, d = 0.70) and a higher score on Item-5h of the PSQI regarding nightmares (p < 0.001, d = 0.59). Women, compared with men, show higher risk [OR = 2.84] for a sleep disorder related to nightmares (p = 0.012). Women need more time to reach a state of alertness after getting up (p = 0.022), and there was an interaction between sex and the alertness factor when evaluating the subjective quality of sleep (p = 0.030). Women show worse sleep quality and a higher frequency and propensity for suffering nightmares. When considering the relationship between sleep quality and academic performance, it is observed that students with poor sleep quality obtain lower academic scores (M = 7.21, SD = 0.805) than those with good sleep quality (M = 7.32, SD = 0.685), an effect that reaches significance (t = 2.116, p = 0.035). Regarding the relationship between the categorized chronotype and academic performance, students with a morning chronotype achieve better academic results (M = 7.41, SD = 0.89) than their evening counterparts (M = 7.15, SD = 0.76), although these differences have a small effect size (d = 0.31).

Animal Models for Functional Gastrointestinal Disorders

Functional gastrointestinal disorders (FGID), such as functional dyspepsia (FD) and irritable bowel syndrome (IBS) are characterized by chronic abdominal symptoms in the absence of an organic, metabolic or systemic cause that readily explains these complaints. Their pathophysiology is still not fully elucidated and animal models have been of great value to improve the understanding of the complex biological mechanisms. Over the last decades, many animal models have been developed to further unravel FGID pathophysiology and test drug efficacy. In the first part of this review, we focus on stress-related models, starting with the different perinatal stress models, including the stress of the dam, followed by a discussion on neonatal stress such as the maternal separation model. We also describe the most commonly used stress models in adult animals which brought valuable insights on the brain-gut axis in stress-related disorders. In the second part, we focus more on models studying peripheral, i.e., gastrointestinal, mechanisms, either induced by an infection or another inflammatory trigger. In this section, we also introduce more recent models developed around food-related metabolic disorders or food hypersensitivity and allergy. Finally, we introduce models mimicking FGID as a secondary effect of medical interventions and spontaneous models sharing characteristics of GI and anxiety-related disorders. The latter are powerful models for brain-gut axis dysfunction and bring new insights about FGID and their comorbidities such as anxiety and depression.

Menstrual Pain: A Review of Foreign Literature

The World Health Organization estimates dysmenorrhea as the most important cause of a chronic pelvic pain. Its prevalence among adolescents and young women ranges from 40 % to 90 %, and varies, depending on age, country of residence and population density of the area. Primary dysmenorrhea is responsible for reducing the quality of life, absenteeism in the workplace or at school, refusing to participate in community and sporting events, changing of pain perception and sleep disturbance. There is evidence of its relationship with an early menarche, a family history, a length of the menstrual cycle, bad habits, poor sleep hygiene, an unbalanced diet, sedentary lifestyle and obesity. Characteristic features of a personality contribute in a certain way, making women prone to neuroticism and pain catastrophizing to be more at risk of developing dysmenorrhea. Irritable bowel syndrome, musculoskeletal pain and interstitial cystitis often accompany dysmenorrhea and respond to its treatment positively. Despite the proven validity of nonsteroidal anti­inflammatory drugs treatment there are resistant forms of menstrual pain, those make a search for alternative therapy relevant.

Persistent autonomic dysfunction and bladder sensitivity in primary dysmenorrhea

Menstrual pain, also known as dysmenorrhea, is a leading risk factor for bladder pain syndrome (BPS). A better understanding of the mechanisms that predispose dysmenorrheic women to BPS is needed to develop prophylactic strategies. Abnormal autonomic regulation, a key factor implicated in BPS and chronic pain, has not been adequately characterized in women with dysmenorrhea. Thus, we examined heart rate variability (HRV) in healthy (n = 34), dysmenorrheic (n = 103), and BPS participants (n = 23) in their luteal phase across a bladder-filling task. Both dysmenorrheic and BPS participants reported increased bladder pain sensitivity when compared to controls (p’s < 0.001). Similarly, dysmenorrheic and BPS participants had increased heart rate (p’s < 0.01), increased diastolic blood pressure (p’s < 0.01), and reduced HRV (p’s < 0.05) when compared to controls. Dysmenorrheic participants also exhibited little change in heart rate between maximum bladder capacity and after micturition when compared to controls (p = 0.013). Our findings demonstrate menstrual pain’s association with abnormal autonomic activity and bladder sensitivity, even two weeks after menses. Our findings of autonomic dysfunction in both early episodic and chronic visceral pain states points to an urgent need to elucidate the development of such imbalance, perhaps beginning in adolescence.

Pelvic organ cross-talk: A new paradigm for endometriosis-related pelvic pain?

Endometriosis patients often complain about pelvic and abdominal pain with varying bowel and bladder symptoms unrelated to the location and extent of the disease. The pathophysiology can be multifactorial, but one possibility is that pelvic organ cross-talk may play a role. The aim of this review was to evaluate the scientific support for this hypothesis. A search was performed in PubMed to identify relevant experimental and clinical studies. Data achieved in animal models and clinical evidence suggest that endometriosis-related pain may implicate interactions between pelvic structures like the urinary tract, the bowel and the vagina, mediated by the autonomous nervous system. Such pelvic organ cross-talk with involvement of nerve fibre outgrowth into endometriosis lesions, peripheral sensitisation and convergence of afferent nerve fibres could be an explanation for the varying pain problems in endometriosis, but the precise mechanisms are still poorly understood. Some patients with chronic pelvic pain, including those with endometriosis, also seem to have a more general somatic, musculoskeletal hyperalgesia, indicating a potential viscero-somatic convergence. This might be due to continuous nociceptive input to the brain, resulting in changes in brain structures and finally leading to central sensitisation. Thus, pelvic organ cross-talk seems to represent a new paradigm for endometriosis-related pain with novel possibilities for the development of therapeutic strategies.

Identification of experimental bladder sensitivity among dysmenorrhea sufferers

BACKGROUND

Dysmenorrhea is a common risk factor for chronic pain conditions including bladder pain syndrome. Few studies have formally evaluated asymptomatic bladder pain sensitivity in dysmenorrhea, and whether this largely reflects excess pelvic symptom reporting due to comorbid psychological dysfunction.

OBJECTIVE

We sought to determine whether bladder hypersensitivity is more common among women reporting moderate or greater dysmenorrhea, without chronic pain elsewhere, after accounting for anxiety and depression. Demonstrating this would suggest that dysmenorrhea might be an early clue for visceral or widespread pain hypersensitivity and improve understanding of potential precursors to bladder pain syndrome.

STUDY DESIGN

We compared cohorts of regularly menstruating women, without symptoms of chronic pain elsewhere, reporting (1) moderate-to-severe dysmenorrhea (n = 98) and (2) low levels or no menstrual pain (n = 35). Participants underwent rapid bladder filling following a standard water ingestion protocol, serially rating bladder pain and relative urgency during subsequent distension. Potential differences in bladder volumes were controlled for by sonographic measurement at standard cystometric thresholds. Bladder sensitivity was also measured with complementary measures at other times separately including a simplified rapid filling test, palpation of the bladder wall, and through ambulatory self-report. Anxiety and depression were evaluated with the National Institutes of Health Patient-Reported Outcomes Measurement Information System measures.

RESULTS

Women with moderate-to-severe dysmenorrhea reported more urinary symptoms than controls and had a lower maximum capacity (498 ± 18 mL vs 619 ± 34 mL, P < .001) and more evoked bladder filling pain (0-100 visual analog scale: 25 ± 3 vs 12 ± 3, P < .001). The dysmenorrhea-bladder capacity relationship remained significant irrespective of menstrual pain severity, anxiety, depression, or bladder pain (R² = 0.13, P = .006). Severity of menstrual pain predicted evoked bladder pain (R² = 0.10, P = .008) independent of anxiety (P = .21) and depression (P = .21). Women with moderate-to-severe dysmenorrhea exhibiting provoked bladder pain (24/98, 24%) also reported higher pain during the screening rapid bladder test (P < .001), in response to transvaginal bladder palpation (P < .015), and on prospective daily diaries (P < .001) than women with dysmenorrhea without provoked bladder pain.

CONCLUSION

Women experiencing moderate-to-severe dysmenorrhea also harbor a higher pain response to naturally evoked bladder distension. Noninvasive bladder provocation needs to be tested further longitudinally in those with dysmenorrhea to characterize the course of visceral sensitivity and determine if it may help predict individuals at risk for developing subsequent pain in the bladder or elsewhere.

Linaclotide Attenuates Visceral Organ Crosstalk: Role of Guanylate Cyclase-C Activation in Reversing Bladder-Colon Cross-Sensitization

Bladder pain syndrome (BPS) is poorly understood; however, there is a female predominance and comorbidity with irritable bowel syndrome (IBS). Here we test the hypothesis that linaclotide, a guanylate cyclase-C (GC-C) agonist approved for the treatment of IBS with constipation (IBS-C), may represent a novel therapeutic for BPS acting through a mechanism involving an inhibition of visceral organ cross-sensitization. We showed previously that infusion of dilute protamine sulfate (PS) into the bladder increased sensitivity and permeability in the bladder and colon. PS was infused into the bladder of female rats; sensitivity was assessed via application of von Frey filaments applied to the suprapubic area and the frequency of withdrawal responses was recorded. Colonic sensitivity was measured via visceromotor behavioral response to graded pressures of colorectal distension (CRD). Permeability was measured in vitro via transepithelial electrical resistance (TEER) and conductance (G). Linaclotide (3 µg/kg, p.o.) or vehicle was administered daily for 7 days prior to experiments. Rats treated with PS bladder infusion exhibited visceral hyperalgesia, as shown by a significantly higher response frequency to individual von Frey filaments and increased behavioral responses to CRD. Linaclotide attenuated bladder and colonic hyperalgesia to control levels. PS infusion into the bladder increased bladder and colon permeability measured as a decrease in TEER and increased G. Linaclotide significantly inhibited PS-induced colonic hyperpermeability while having no effect on bladder hyperpermeability. Our findings suggest a novel treatment paradigm for GC-C agonism in IBS-C and BPS mediated through a mechanism involving visceral organ crosstalk.

Nonsteroidal antiinflammatory drug resistance in dysmenorrhea: epidemiology, causes, and treatment

Although nonsteroidal antiinflammatory drugs can alleviate menstrual pain, about 18% of women with dysmenorrhea are unresponsive, leaving them and their physicians to pursue less well-studied strategies. The goal of this review is to provide a background for treating menstrual pain when first-line options fail. Research on menstrual pain and failure of similar drugs in the antiplatelet category suggested potential mechanisms underlying nonsteroidal antiinflammatory drug resistance. Based on these mechanisms, alternative options may be helpful for refractory cases. This review also identifies key pathways in need of further study to optimize menstrual pain treatment.

Cross-organ sensitization between the colon and bladder: to pee or not to pee?

Chronic abdominal and pelvic pain are common debilitating clinical conditions experienced by millions of patients around the globe. The origin of such pain commonly arises from the intestine and bladder, which share common primary roles (the collection, storage, and expulsion of waste). These visceral organs are located in close proximity to one another and also share common innervation from spinal afferent pathways. Chronic abdominal pain, constipation, or diarrhea are primary symptoms for patients with irritable bowel syndrome or inflammatory bowel disease. Chronic pelvic pain and urinary urgency and frequency are primary symptoms experienced by patients with lower urinary tract disorders such as interstitial cystitis/painful bladder syndrome. It is becoming clear that these symptoms and clinical entities do not occur in isolation, with considerable overlap in symptom profiles across patient cohorts. Here we review recent clinical and experimental evidence documenting the existence of "cross-organ sensitization" between the colon and bladder. In such circumstances, colonic inflammation may result in profound changes to the sensory pathways innervating the bladder, resulting in severe bladder dysfunction.

The Pelvis and Beyond: Musculoskeletal Tender Points in Women With Chronic Pelvic Pain

OBJECTIVE

To determine the feasibility of a detailed pain sensitivity assessment using body-wide musculoskeletal tender points (TPs) in women with different types of chronic pelvic pain (CPP) and compare phenotypic differences.

MATERIALS AND METHODS

Seventy women with CPP and 35 pain-free women underwent musculoskeletal evaluation of TPs in the pelvic floor, abdomen, groin, inner thigh, and all 18 fibromyalgia TPs. Patients scored elicited pain on a numeric rating scale. TP pain scores were used for intergroup comparison and intragroup correlation.

RESULTS

Women with CPP were grouped as having either bladder pain syndrome (BPS, n=24) or myofascial pelvic pain (MPP, n=11) singularly or both concomitantly (BPS+MPP, n=35). TP pain scores for all evaluations were higher in women with CPP compared with healthy women (P<0.001). Women with BPS+MPP had elevated TP pain for each evaluation compared with women with BPS alone. Pelvic floor and fibromyalgia TP scores correlated strongly in the MPP group, moderately in the BPS+MPP group, and weakly in the BPS alone group. Although some moderate and strong correlations between different body locations were present in all 3 groups, only the BPS+MPP group showed moderate to strong correlations between all body TPs.

CONCLUSIONS

Detailed musculoskeletal evaluation of women with CPP is feasible and well tolerated. Careful phenotyping differentiated BPS, MPP, and BPS+MPP groups. Attending to the differences between these groups clinically may lead to more effective treatment strategies and improved outcomes for patients with CPP.

Clinical utility of neurostimulation devices in the treatment of overactive bladder: current perspectives

Objectives

This review describes the evidence from established and experimental therapies that use electrical nerve stimulation to treat lower urinary tract dysfunction.

Methods

Clinical studies on established treatments such as percutaneous posterior tibial nerve stimulation (P-PTNS), transcutaneous electrical nerve stimulation (TENS), sacral nerve stimulation (SNS) and sacral anterior root stimulation (SARS) are evaluated. In addition, clinical evidence from experimental therapies such as dorsal genital nerve (DGN) stimulation, pudendal nerve stimulation, magnetic nerve stimulation and ankle implants for tibial nerve stimulation are evaluated.

Results

SNS and P-PTNS have been investigated with high-quality studies that have shown proven efficacy for the treatment for overactive bladder (OAB). SARS has proven evidence-based efficacy in spinal cord patients and increases the quality of life. TENS seems inferior to other OAB treatments such as SNS and P-PTNS but is noninvasive and applicable for ambulant therapy. Results from studies on experimental therapies such as pudendal nerve stimulation seem promising but need larger study cohorts to prove efficacy.

Conclusion

Neurostimulation therapies have proven efficacy for bladder dysfunction in patients who are refractory to other therapies.

Significance

Refinement of neurostimulation therapies is possible. The aim should be to make the treatments less invasive, more durable and more effective for the treatment of lower urinary tract dysfunction.

Genitourinary and gastrointestinal co-morbidities in children: The role of neural circuits in regulation of visceral function

OBJECTIVE

Pediatric lower urinary tract dysfunction (LUTD) is a common problem in childhood. Lower urinary tract symptoms in children include overactive bladder, voiding postponement, stress incontinence, giggle incontinence, and dysfunctional voiding. Gastrointestinal co-morbidities, including constipation or fecal incontinence, are commonly associated with lower urinary tract (LUT) symptoms in children, often reaching 22-34%. This review summarized the potential mechanisms underlying functional lower urinary and gastrointestinal co-morbidities in children. It also covered the current understanding of clinical pathophysiology in the pediatric population, anatomy and embryological development of the pelvic organs, role of developing neural circuits in regulation of functional co-morbidities, and relevant translational animal models.

MATERIALS AND METHODS

This was a non-systematic review of the published literature, which summarized the available clinical and translational studies on functional urologic and gastrointestinal co-morbidities in children, as well as neural mechanisms underlying pelvic organ 'cross-talk' and 'cross-sensitization'.

RESULTS

Co-morbidity of pediatric lower urinary and gastrointestinal dysfunctions could be explained by multiple factors, including a shared developmental origin, close anatomical proximity, and pelvic organ 'cross-talk'. Daily physiological activity and viscero-visceral reflexes between the lower gastrointestinal and urinary tracts are controlled by both autonomic and central nervous systems, suggesting the dominant modulatory role of the neural pathways. Recent studies have provided evidence that altered sensation in the bladder and dysfunctional voiding can be triggered by pathological changes in neighboring pelvic organs due to a phenomenon known as pelvic organ 'cross-sensitization'. Cross-sensitization between pelvic organs is thought to be mainly coordinated by convergent neurons that receive dual afferent inputs from discrete pelvic organs. Investigation of functional changes in nerve fibers and neurons sets certain limits in conducting appropriate research in humans, making the use of animal models necessary to uncover the underlying mechanisms and for the development of novel therapeutic approaches for long-term symptomatic treatment of LUTD in the pediatric population.

CONCLUSION

Pediatric LUTD is often complicated by gastrointestinal co-morbidities; however, the mechanisms linking bladder and bowel dysfunctions are not well understood. Clinical studies have suggested that therapeutic modulation of one system may improve the other system's function. To better manage children with LUTD, the interplay between the two systems, and how co-morbid GI and voiding dysfunctions can be more specifically targeted in pediatric clinics need to be understood.

Local upregulation of transient receptor potential ankyrin 1 and transient receptor potential vanilloid 1 ion channels in rectosigmoid deep infiltrating endometriosis

Transient Receptor Potential Vanilloid 1 (TRPV1) and Transient Receptor Potential Ankyrin 1 (TRPA1) expressed mainly by primary sensory neurons function as major nociceptive integrators. They are also present on the rat endometrium in an oestrogen-regulated manner. TRPV1 is upregulated in peritoneal and ovarian endometriosis patients, but there is no information about TRPA1 and their pathophysiological significances. In this study, patients undergoing laparoscopic surgery were investigated: severe dysmenorrhoea due to rectosigmoid deep infiltrating endometriosis ( n = 15), uterine fibroid-induced moderate dysmenorrhoea ( n = 7) and tubal infertility with no pain ( n = 6). TRPA1 and TRPV1 mRNA and protein expressions were determined by quantitative polymerase chain reaction and semi-quantitative immunohistochemistry from the endometrium samples taken by curettage. Results were correlated with the clinical characteristics including pain intensity. TRPA1 and TRPV1 receptors were expressed in the healthy human endometrium at mRNA and protein levels. Sparse, scattered cytoplasmic TRPA1 and TRPV1 immunopositivities were found in the stroma and epithelial layers. We detected upregulated mRNA levels in deep infiltrating endometriosis lesions, and TRPV1 gene expression was also elevated in autocontrol endometrium of deep infiltrating endometriosis patients. Histological scoring revealed significant TRPA1 and TRPV1 difference between deep infiltrating endometriosis stroma and epithelium, and in deep infiltrating endometriosis epithelium compared to control samples. Besides, we measured elevated stromal TRPV1 immunopositivity in deep infiltrating endometriosis. Stromal TRPA1 and TRPV1 immunoreactivities strongly correlated with dysmenorrhoea severity, as well TRPV1 expression on ectopic epithelial cells and macrophages with dyspareunia. Epithelial TRPA1 and stromal TRPV1 immunopositivity also positively correlated with dyschezia severity. We provide the first evidence for the presence of non-neuronal TRPA1 receptor in the healthy human endometrium and confirm the expression of TRPV1 channels. Their upregulations in rectosigmoid deep infiltrating endometriosis lesions and correlations with pain intensity suggest potential roles in pathophysiological mechanisms of the disease.

Correlation Between Bladder Pain Syndrome/Interstitial Cystitis and Pelvic Inflammatory Disease

Pelvic inflammatory disease (PID) has been investigated in Western countries and identified to be associated with chronic pelvic pain and inflammation. Bladder pain syndrome/interstitial cystitis (BPS/IC) is a complex syndrome that is significantly more prevalent in women than in men. Chronic pelvic pain is a main symptom of BPS/IC, and chronic inflammation is a major etiology of BPS/IC. This study aimed to investigate the correlation between BPS/IC and PID using a population-based dataset.We constructed a case-control study from the Taiwan National Health Insurance program. The case cohort comprised 449 patients with BPS/IC, and 1796 randomly selected subjects (about 1:4 matching) were used as controls. A Multivariate logistic regression model was constructed to estimate the association between BPS/IC and PID.Of the 2245 sampled subjects, a significant difference was observed in the prevalence of PID between BPS/IC cases and controls (41.7% vs 15.4%, P < 0.001). Multivariate logistic regression analysis revealed that the odds ratio (OR) for PID among cases was 3.69 (95% confidence interval [CI]: 2.89-4.71). Furthermore, the ORs for PID among BPS/IC cases were 4.52 (95% CI: 2.55-8.01), 4.31 (95% CI: 2.91-6.38), 3.00 (95% CI: 1.82-4.94), and 5.35 (95% CI: 1.88-15.20) in the <35, 35-49, 50-64, and >65 years age groups, respectively, after adjusting for geographic region, irritable bowel syndrome, and hypertension. Joint effect was also noted, specifically when patients had both PID and irritable bowel disease with OR of 10.5 (95% CI: 4.88-22.50).This study demonstrated a correlation between PID and BPS/IC. Clinicians treating women with PID should be alert to BPS/IC-related symptoms in the population.

Mechanisms of Visceral Organ Crosstalk: Importance of Alterations in Permeability in Rodent Models

PURPOSE

The pathophysiology of painful bladder syndrome is poorly understood. However, there is evidence of female predominance and comorbidity with irritable bowel syndrome. Our hypothesis is that cross-sensitization between bladder and colon is due to altered permeability in 1 organ, which affects the other organ.

MATERIALS AND METHODS

Experiments were performed in anesthetized, ovariectomized female rats. In separate groups protamine sulfate was infused in the bladder or trinitrobenzene sulfonic acid was infused in the colon. Untreated rats served as controls. Bladder and colonic tissue were harvested from all rats 1, 3 and 5 days after treatment. Permeability was assessed in vitro in Ussing chambers by measuring transepithelial electrical resistance and macromolecular flux of fluorescein isothiocyanate-dextran.

RESULTS

Exposing the bladder to protamine sulfate induced a significant decrease in bladder transepithelial electrical resistance and an increase in the translocation of fluorescein isothiocyanate across the tissue compared to controls at 1 and 3 days (p <0.05). Colonic tissue from rats with enhanced bladder permeability showed a significant decrease in transepithelial electrical resistance and increase in fluorescein isothiocyanate compared to untreated controls at all time points (p <0.05). Conversely when colonic permeability was increased with trinitrobenzene sulfonic acid, we observed an increase in bladder permeability in the absence of any changes to the bladder urothelium.

CONCLUSIONS

Changes in epithelial permeability may represent a novel mechanism for visceral organ crosstalk. It may explain the overlapping symptomology of painful bladder syndrome and irritable bowel syndrome.

Innervation of enteric mast cells by primary spinal afferents in guinea pig and human small intestine

Mast cells express the substance P (SP) neurokinin 1 receptor and the calcitonin gene-related peptide (CGRP) receptor in guinea pig and human small intestine. Enzyme-linked immunoassay showed that activation of intramural afferents by antidromic electrical stimulation or by capsaicin released SP and CGRP from human and guinea pig intestinal segments. Electrical stimulation of the afferents evoked slow excitatory postsynaptic potentials (EPSPs) in the enteric nervous system. The slow EPSPs were mediated by tachykinin neurokinin 1 and CGRP receptors. Capsaicin evoked slow EPSP-like responses that were suppressed by antagonists for protease-activated receptor 2. Afferent stimulation evoked slow EPSP-like excitation that was suppressed by mast cell-stabilizing drugs. Histamine and mast cell protease II were released by 1) exposure to SP or CGRP, 2) capsaicin, 3) compound 48/80, 4) elevation of mast cell Ca²⁺ by ionophore A23187, and 5) antidromic electrical stimulation of afferents. The mast cell stabilizers cromolyn and doxantrazole suppressed release of protease II and histamine when evoked by SP, CGRP, capsaicin, A23187, electrical stimulation of afferents, or compound 48/80. Neural blockade by tetrodotoxin prevented mast cell protease II release in response to antidromic electrical stimulation of mesenteric afferents. The results support a hypothesis that afferent innervation of enteric mast cells releases histamine and mast cell protease II, both of which are known to act in a diffuse paracrine manner to influence the behavior of enteric nervous system neurons and to elevate the sensitivity of spinal afferent terminals.

A noninvasive bladder sensory test supports a role for dysmenorrhea increasing bladder noxious mechanosensitivity

OBJECTIVE

Catheterization to measure bladder sensitivity is aversive and hinders human participation in visceral sensory research. Therefore, we sought to characterize the reliability of sonographically estimated female bladder sensory thresholds. To demonstrate this technique's usefulness, we examined the effects of self-reported dysmenorrhea on bladder pain thresholds.

METHODS

Bladder sensory threshold volumes were determined during provoked natural diuresis in 49 healthy women (mean age, 24±8 y) using 3-dimensional ultrasound. Cystometric thresholds (Vfs, first sensation; Vfu, first urge; Vmt, maximum tolerance) were quantified and related to bladder urgency and pain. We estimated the reliability (1-wk retest and interrater). Self-reported menstrual pain was examined in relationship to bladder pain, urgency, and volume thresholds.

RESULTS

Average bladder sensory thresholds (mL) were Vfs (160±100), Vfu (310±130), and Vmt (500±180). Interrater reliability ranged from 0.97 to 0.99. One-week retest reliability was Vmt=0.76 (95% CI, 0.64-0.88), Vfs=0.62 (95% CI, 0.44-0.80), and Vfu=0.63 (95% CI, 0.47-0.80). Bladder filling rate correlated with all thresholds (r=0.53 to 0.64, P<0.0001). Women with moderate to severe dysmenorrhea pain had increased bladder pain and urgency at Vfs and increased pain at Vfu (P's<0.05). In contrast, dysmenorrhea pain was unrelated to bladder capacity.

DISCUSSION

Sonographic estimates of bladder sensory thresholds were reproducible and reliable. In these healthy volunteers, dysmenorrhea was associated with increased bladder pain and urgency during filling but unrelated to capacity. Plausibly, women with dysmenorrhea may exhibit enhanced visceral mechanosensitivity, increasing their risk to develop chronic bladder pain syndromes.

Neurobiological mechanisms of pelvic pain

Pelvic pain is a common condition which significantly deteriorates health-related quality of life. The most commonly identified causes of pain in the pelvic region are gynaecologic, urologic, gastrointestinal, neurological, and musculoskeletal. However, in up to 33% of patients the source of this symptom is not identified, frustrating both patients and health-care professionals. Pelvic pain may involve both the somatic and visceral systems, making the differential diagnosing challenging. This paper aimed to review the mechanisms involved in pelvic pain perception by analyzing the neural plasticity and molecules which are involved in these complex circuits.

Visceral syndrome in endometriosis patients

OBJECTIVE

Pain related to bowel and bladder function is seen more often in endometriosis. This study explored whether employed endometriosis patients experience multiple visceral symptoms more often than reference women without the disease.

STUDY DESIGN

In a cohort study, 610 patients with diagnosed endometriosis and 751 reference women completed an electronic survey based on the EHP-30 questionnaire. Percentages were reported for all data. Principal component analysis was used to find underlying structures of correlations among variables, and Cronbach's alpha reliability analysis was used to demonstrate internal consistency of each scale. The level of statistical significance was set at p<0.025 in all the analyses.

RESULTS

Principal component analysis pointed at a specific visceral symptom-complex relating to the abdominal organs. This correlation was called "visceral syndrome" and consisted of the seven symptoms; "abdominal pain with no relation to menstruation", "pain during urination", "pain during defecation", "constipation or diarrhea", "irregular bleeding", "nausea or vomiting" and "feeling tired/lack of energy", with a Cronbach's alpha value α=0.85. More women with endometriosis than reference women suffered between five and seven symptoms from the visceral syndrome (22.7% vs. 2.7%) and more women with endometriosis compared to women with pain from other conditions suffered between five and seven symptoms from the visceral syndrome (22.7% vs. 3.2%).

CONCLUSION

These data indicate that a significant number of endometriosis patients suffer from a specific symptom correlation, which is uncommon in women without the disease. These findings and previous data may suggest the occurrence of a visceral syndrome in endometriosis.

Peripheral changes in endometriosis-associated pain

BACKGROUND

Pain remains the cardinal symptom of endometriosis. However, to date, the underlying mechanisms are still only poorly understood. Increasing evidence points towards a close interaction between peripheral nerves, the peritoneal environment and the central nervous system in pain generation and processing. Recently, studies demonstrating nerve fibres and neurotrophic and angiogenic factors in endometriotic lesions and their vicinity have led to increased interest in peripheral changes in endometriosis-associated pain. This review focuses on the origin and function of these nerves and factors as well as possible peripheral mechanisms that may contribute to the generation and modulation of pain in women with endometriosis.

METHODS

We conducted a systematic search using several databases (PubMed, MEDLINE, EMBASE and CINAHL) of publications from January 1977 to October 2013 to evaluate the possible roles of the peripheral nervous system in endometriosis pathophysiology and how it can contribute to endometriosis-associated pain.

RESULTS

Endometriotic lesions and peritoneal fluid from women with endometriosis had pronounced neuroangiogenic properties with increased expression of new nerve fibres, a shift in the distribution of sensory and autonomic fibres in some locations, and up-regulation of several neurotrophins. In women suffering from deep infiltrating endometriosis and bowel endometriosis, in which the anatomical distribution of lesions is generally more closely related to pelvic pain symptoms, endometriotic lesions and surrounding tissues present higher nerve fibre densities compared with peritoneal lesions and endometriomas. More data are needed to fully confirm a direct correlation between fibre density in these locations and the amount of perceived pain. A better correlation between the presence of nerve fibres and pain symptoms seems to exist for eutopic endometrium. However, this appears not to be exclusive to endometriosis. No correlation between elevated neurotrophin levels and pain severity appears to exist, suggesting the involvement of other mediators in the modulation of pain.

CONCLUSIONS

The increased expression of neurotrophic factors and nerve fibres in endometriotic lesions, eutopic endometrium and the peritoneum imply a role of such peripheral changes in the pathogenesis of endometriosis-associated pain. However, a clear link between these findings and pain in patients with endometriosis has so far not been demonstrated.

Cross-sensitization mechanisms between colon and bladder via transient receptor potential A1 stimulation in rats

INTRODUCTION AND HYPOTHESIS

The aim of this study was to analyze the mechanism underlying cross-sensitization between the colon and the bladder via activation of transient receptor potential A1 (TRPA1) channels.

METHODS

Using female Sprague-Dawley rats, polyethylene catheters were inserted into the colon between two ligations at the levels of 40 and 60 mm rostral to the anus and into the bladder. (1) We examined changes in colon and bladder activity after the application of allyl isothiocyanate (AI, 50 mM, 300 μl), a TRPA1 activator, into the colon or the bladder in an awake condition. Inhibitory effects of the pretreatment with HC-030031 (HC, 3 mg/kg), a TRPA1 inhibitor, on colon-to-bladder cross-sensitization induced by AI instilled in the colon were also investigated. (2) We examined Evans blue (EB) dye extravasation after TRPA1 stimulation in the colon or the bladder to evaluate vascular permeability due to tissue inflammation.

RESULTS

(1) Intercontraction intervals during continuous saline infusion into the bladder (0.04 ml/min) were significantly decreased after the intracolonic AI application, which significantly increased mean intracolonic pressure, indicative of colon-to-bladder cross-sensitization. The AI-induced colon-to-bladder cross-sensitization was completely prevented by the pretreatment with intravenous application of HC. On the other hand, mean intracolonic pressure was significantly decreased after the intravesical AI application, which significantly increased mean intravesical pressure. (2) EB dye extravasation was significantly increased in the AI-treated inflamed organs and also in the bladder following intracolonic AI treatment.

CONCLUSIONS

Colon-to-bladder cross-sensitization is mediated via TRPA1 stimulation in the colon, although TRPA1 expressed in the bladder does not seem to participate in bladder-to-colon cross-sensitization.

A new mouse model for female genital schistosomiasis

BACKGROUND

Over 112 million people worldwide are infected with Schistosoma haematobium, one of the most prevalent schistosome species affecting humans. Female genital schistosomiasis (FGS) occurs when S. haematobium eggs are deposited into the female reproductive tract by adult worms, which can lead to pelvic pain, vaginal bleeding, genital disfigurement and infertility. Recent evidence suggests co-infection with S. haematobium increases the risks of contracting sexually transmitted diseases such as HIV. The associated mechanisms remain unclear due to the lack of a tractable animal model. We sought to create a mouse model conducive to the study of immune modulation and genitourinary changes that occur with FGS.

METHODS

To model FGS in mice, we injected S. haematobium eggs into the posterior vaginal walls of 30 female BALB/c mice. A control group of 20 female BALB/c mice were injected with uninfected LVG hamster tissue extract. Histology, flow cytometry and serum cytokine levels were assessed at 2, 4, 6, and 8 weeks post egg injection. Voiding studies were performed at 1 week post egg injection.

RESULTS

Vaginal wall injection with S. haematobium eggs resulted in synchronous vaginal granuloma development within 2 weeks post-egg injection that persisted for at least 6 additional weeks. Flow cytometric analysis of vaginal granulomata revealed infiltration by CD4+ T cells with variable expression of the HIV co-receptors CXCR4 and CCR5. Granulomata also contained CD11b+F4/80+ cells (macrophages and eosinophils) as well as CXCR4+MerTK+ macrophages. Strikingly, vaginal wall-injected mice featured significant urinary frequency despite the posterior vagina being anatomically distant from the bladder. This may represent a previously unrecognized overactive bladder response to deposition of schistosome eggs in the vagina.

CONCLUSION

We have established a new mouse model that could potentially enable novel studies of genital schistosomiasis in females. Ongoing studies will further explore the mechanisms by which HIV target cells may be drawn into FGS-associated vaginal granulomata.

Estrous cycle dependent fluctuations of regulatory neuropeptides in the lower urinary tract of female rats upon colon-bladder cross-sensitization

Co-morbidity of bladder, bowel, and non-specific pelvic pain symptoms is highly prevalent in women. Little evidence is present on modulation of pelvic pain syndromes by sex hormones, therefore, the objective of this study was to clarify the effects of hormonal fluctuations within the estrous cycle on regulatory neuropeptides in female rats using a model of neurogenic bladder dysfunction. The estrous cycle in female rats (Sprague-Dawley, 230-250 g) was assessed by vaginal smears and weight of uterine horns. Neurogenic bladder dysfunction was induced by a single inflammatory insult to the distal colon. Protein expression of calcitonin gene related peptide (CGRP), substance P (SP), nerve growth factor (NGF), and brain derived neurotrophic factor (BDNF) in the pelvic organs, sensory ganglia and lumbosacral spinal cord was compared in rats in proestrus (high estrogen) vs diestrus (low estrogen). Under normal physiological conditions, concentration of SP and CGRP was similar in the distal colon and urinary bladder during all phases of the estrous cycle, however, acute colitis induced a significant up-regulation of CGRP content in the colon (by 63%) and urinary bladder (by 54%, p≤0.05 to control) of rats in proestrus. These changes were accompanied by a significant diminution of CGRP content in L6-S2 DRG after colonic treatment, likely associated with its release in the periphery. In rats with high estrogen at the time of testing (proestrus), experimental colitis caused a significant up-regulation of BDNF colonic content from 26.1±8.5 pg/ml to 83.4±32.5 pg/ml (N = 7, p≤0.05 to control) and also induced similar effects on BDNF in the urinary bladder which was also up-regulated by 5-fold in rats in proestrus (p≤0.05 to respective control). Our results demonstrate estrous cycle dependent fluctuations of regulatory neuropeptides in the lower urinary tract upon colon-bladder cross-sensitization, which may contribute to pain fluctuations in female patients with neurogenic bladder pain.

Female reproductive tract pain: targets, challenges, and outcomes

Pain from the female reproductive tract (FRT) is a significant clinical problem for which there are few effective therapies. The complex neuroanatomy of pelvic organs not only makes diagnosis of pelvic pain disorders difficult but represents a challenge to development of targeted therapies. A number of potential therapeutic targets have been identified on sensory neurons supplying the FRT but our knowledge on the basic neurophysiology of these neurons is limited compared with other viscera. Until this is addressed we can only guess if the new experimental therapies proposed for somatic, gastrointestinal, or bladder pain will translate to the FRT. Once suitable therapeutic targets become clear, the next challenge is drug delivery. The FRT represents a promising system for topical drug delivery that could be tailored to act locally or systemically depending on formulation. Development of these therapies and their delivery systems will need to be done in concert with more robust in vivo and in vitro models of FRT pain.

Acute Uterine Irritation Provokes Colonic Motility via Transient Receptor Potential A1-dependent Spinal NR2B Phosphorylation in Rats

Background:

Patients with inflammatory gynecological/obstetrical problems often complain of irritable bowel syndrome. The authors examined whether acute uterus irritation reflexively provokes colonic motility in rat preparations.

Methods:

A modified colon manometry and striated abdominal muscle electromyogram activity in response to mustard oil (MO) instillation into the uterine horn were continuously recorded in anesthetized rats. The lumbosacral (L6-S1) dorsal horn was dissected to assess the level and the cellular location of phosphorylated NR2B subunit using Western blotting and immunofluorescence analysis, respectively. Finally, the uterine transient receptor potential A1 or spinal NR2B subunit was pharmacologically blocked to elucidate its roles.

Results:

MO (0.1%, 0.2 ml) injected into the lower uterine horn dramatically provoked colonic hypermotility characterized by rhythmic colonic contractions (about 3–4 contractions per 10 min, n = 7) accompanied by synchronized electromyogram firing in the abdominal muscle (about 4–5 folds of control, n = 7). In addition to provoking colonic hypermotility, MO administration also up-regulated phosphorylated (about 2–3 folds of control, n = 7), but not total, NR2B expression in the dorsal horn neurons. Both intrathecal Ro 25–6981 (a selective NR2B subunit antagonist; 10 μM, 10 μl) and intrauterine HC-030031 (a selective transient receptor potential A1 receptor antagonist; 30 mg/kg, 0.2 ml) injected before the MO instillation attenuated the MO-induced colonic hypermotility and spinal NR2B phosphorylation.

Conclusion:

The comorbidity of gynecological/obstetrical and gastrointestinal problems is not coincidental but rather causal in nature, and clinicians should investigate for gynecological/urological diseases in the setting of bowel problems with no known pathological etiology.

A systematic review of the evidence for central nervous system plasticity in animal models of inflammatory-mediated gastrointestinal pain

BACKGROUND

Abdominal pain frequently accompanies inflammatory disorders of the gastrointestinal tract (GIT), and animal models of GIT inflammation have been developed to explore the role of the central nervous system (CNS) in this process. Here, we summarize the evidence from animal studies for CNS plasticity following GIT inflammation.

METHODS

A systematic review was conducted to identify studies that: (1) used inflammation of GIT organs, (2) assessed pain or visceral hypersensitivity, and (3) presented evidence of CNS involvement. Two hundred and eight articles were identified, and 79 were eligible for analysis.

RESULTS

Rats were most widely used (76%). Most studies used adult animals (42%) with a bias toward males (74%). Colitis was the most frequently used model (78%) and 2,4,6-trinitrobenzenesulfonic acid the preferred inflammatory agent (33%). Behavioral (58%), anatomical/molecular (44%), and physiological (24%) approaches were used alone or in combination to assess CNS involvement during or after GIT inflammation. Measurement times varied widely (<1 h-> 2 wk after inflammation). Blinded outcomes were used in 42% studies, randomization in 10%, and evidence of visceral inflammation in 54%. Only 3 studies fulfilled our criteria for high methodological quality, and no study reported sample size calculations.

CONCLUSIONS

The included studies provide strong evidence for CNS plasticity following GIT inflammation, specifically in the spinal cord dorsal horn. This evidence includes altered visceromotor responses and indices of referred pain, elevated neural activation and peptide content, and increased neuronal excitability. This evidence supports continued use of this approach for preclinical studies; however, there is substantial scope to improve study design.

The association of dysmenorrhea with noncyclic pelvic pain accounting for psychological factors

OBJECTIVE

The factors that underlie pelvic pain are poorly understood. Specifically, the relative influence of dysmenorrhea and psychological factors in the etiology of noncyclic pelvic pain conditions, such as interstitial cystitis and irritable bowel syndrome, is unknown. To further characterize pelvic pain, we compared the frequency of menstrual, somatosensory, and psychological risk factors between women with and without severe noncyclic pelvic pain symptoms.

STUDY DESIGN

A total of 1012 reproductive-aged women completed a 112-item questionnaire with domains including mood, fatigue, physical activity, somatic complaint, and pain. Questionnaire items included existing items for menstrual distress and newly written items derived from qualitative interviews. The relationship of dysmenorrhea and noncyclic pelvic pain complaints (dyspareunia, dyschezia, or dysuria) was modeled using quantile regression.

RESULTS

Among women who menstruate regularly, those with dysmenorrhea had disproportionally more severe noncyclic pelvic pain (54/402, 13%) than women without dysmenorrhea (5/432, 1%; odds ratio, 13; 95% confidence interval, 5-33). In a multivariate-adjusted model, dysmenorrhea (β = .17), activity capability (β = .17), somatic complaint (β = .17), and bodily pain (β = .12) were the primary predictors of noncyclic pelvic pain. Depression (β = .03) and anxiety (β = .01) were not significantly predictive. The presence of dysmenorrhea, somatic complaint, and low activity capability predicted 90% of the cases of women with noncyclic pelvic pain.

CONCLUSION

The association between dysmenorrhea and noncyclic pelvic pain suggests that menstrual pain is an etiological factor in noncyclic pelvic pain, whereas depression and anxiety may be secondary effects. Longitudinal studies are needed to determine whether dysmenorrhea causally influences development of noncyclic pelvic pain or shares common underlying neural mechanisms.

Convergence and cross talk in urogenital neural circuitries

Despite common comorbidity of sexual and urinary dysfunctions, the interrelationships between the neural control of these functions are poorly understood. The medullary reticular formation (MRF) contributes to both mating/arousal functions and micturition, making it a good site to test circuitry interactions. Urethane-anesthetized adult Wistar rats were used to examine the impact of electrically stimulating different nerve targets [dorsal nerve of the penis (DNP) or clitoris (DNC); L6/S1 trunk] on responses of individual extracellularly recorded MRF neurons. The effect of bladder filling on MRF neurons was also examined, as was stimulation of DNP on bladder reflexes via cystometry. In total, 236 MRF neurons responded to neurostimulation: 102 to DNP stimulation (12 males), 64 to DNC stimulation (12 females), and 70 to L6/S1 trunk stimulation (12 males). Amplitude thresholds were significantly different at DNP (15.0 ± 0.6 μA), DNC (10.5 ± 0.7 μA), and L6/S1 trunk (54.2 ± 4.6 μA), whereas similar frequency responses were found (max responses near 30–40 Hz). In five males, filling/voiding cycles were lengthened with DNP stimulation (11.0 ± 0.9 μA), with a maximal effective frequency plateau beginning at 30 Hz. Bladder effects lasted ∼2 min after DNP stimulus offset. Many MRF neurons receiving DNP/DNC input responded to bladder filling (35.0% and 68.3%, respectively), either just before (43%) or simultaneously with (57%) the voiding reflex. Taken together, MRF-evoked responses with neurostimulation of multiple nerve targets along with different responses to bladder infusion have implications for the role of MRF in multiple aspects of urogenital functions.

Chiropractic care of interstitial cystitis/painful bladder syndrome associated with pelvic lumbar spine dysfunction: a case series

OBJECTIVE

The purpose of this case series is to describe findings for patients with bladder pain syndrome (BPS) or interstitial cystitis (IC) who responded positively under chiropractic care.

CLINICAL FEATURES

Eight cases were selected retrospectively reviewed from 2 independent chiropractic clinics in Scotland. Cases were selected if patients reported bladder dysfunction problems and responded positively to chiropractic care. The cases in this report describe the range of patients affected by this condition. Each patient was treated using chiropractic methods that were specific to the individual case.

INTERVENTION AND OUTCOMES

The patients selected for this case series showed positive response to chiropractic care over various lengths of time and numbers of treatments. Some of the chiropractic patients who had chronic spinal conditions had reoccurrence of bladder symptoms during an exacerbation of mechanical spinal problems.

CONCLUSION

This case series highlights that bladder and urinary problems may be associated with spinal dysfunction for some patients.

Anatomical and functional characterization of a duodeno-pancreatic neural reflex that can induce acute pancreatitis

Neural cross talk between visceral organs may play a role in mediating inflammation and pain remote from the site of the insult. We hypothesized such a cross talk exists between the duodenum and pancreas, and further it induces pancreatitis in response to intraduodenal toxins. A dichotomous spinal innervation serving both the duodenum and pancreas was examined, and splanchnic nerve responses to mechanical stimulation of these organs were detected. This pathway was then excited on the duodenal side by exposure to ethanol followed by luminal mustard oil to activate transient receptor potential subfamily A, member 1 (TRPA1). Ninety minutes later, pancreatic inflammation was examined. Ablation of duodenal afferents by resiniferatoxin (RTX) or blocking TRPA1 by Chembridge (CHEM)-5861528 was used to further investigate the duodeno-pancreatic neural reflex via TRPA1. ~40% of dorsal root ganglia (DRG) from the spinal cord originated from both duodenum and pancreas via dichotomous peripheral branches; ~50% splanchnic nerve single units responded to mechanical stimulation of both organs. Ethanol sensitized TRPA1 currents in cultured DRG neurons. Pancreatic edema and myeloperoxidase activity significantly increased after intraduodenal ethanol followed by mustard oil (but not capsaicin) but significantly decreased after ablation of duodenal afferents by using RTX or blocking TRPA1 by CHEM-5861528. We found the existence of a neural cross talk between the duodenum and pancreas that can promote acute pancreatitis in response to intraduodenal chemicals. It also proves a previously unexamined mechanism by which alcohol can induce pancreatitis, which is novel both in terms of the site (duodenum), process (neurogenic), and receptor (TRPA1).

Do the urinary bladder and large bowel interact, in sickness or in health? ICI-RS 2011

Normal functioning of the urinary bladder and the distal gut is an essential part of daily physiological activity coordinated by the peripheral and central nervous systems. Pathological changes in one of these organs may induce the development of cross-organ sensitization in the pelvis and underlie clinical co-morbidity of genitourinary and GI dysfunctions. Experimental human and animal data suggest that the bladder and distal colon interact under both normal and pathological conditions, however, the directions of these interactions can change dramatically depending on the nature and duration of the applied stimuli. This review article aimed to summarize the clinical data on colon-bladder cross-reflexes in healthy individuals, as well as in patients with co-morbid disorders. It also discusses currently used animal models, experimental approaches, and suggested mechanisms of colon-bladder cross-talk. Additionally, it provides an overview of the potential pharmacological targets to develop treatment options for patients with co-morbid disorders. Presented work resulted from the discussion of colon/bladder interactions during "Think Tank 9" presentations at the International Consultation on Incontinence Research Society meeting held in Bristol, UK, 2011.

Recognition and management of nonrelaxing pelvic floor dysfunction

Nonrelaxing pelvic floor dysfunction is not widely recognized. Unlike in pelvic floor disorders caused by relaxed muscles (eg, pelvic organ prolapse or urinary incontinence, both of which often are identified readily), women affected by nonrelaxing pelvic floor dysfunction may present with a broad range of nonspecific symptoms. These may include pain and problems with defecation, urination, and sexual function, which require relaxation and coordination of pelvic floor muscles and urinary and anal sphincters. These symptoms may adversely affect quality of life. Focus on the global symptom complex, rather than the individual symptoms, may help the clinician identify the condition. The primary care provider is in a position to intervene early, efficiently, and effectively by (1) recognizing the range of symptoms that might suggest nonrelaxing pelvic floor dysfunction, (2) educating patients, (3) performing selective tests when needed to confirm the diagnosis, and (4) providing early referral for physical therapy.

Gender specific pelvic pain severity in neurogenic cystitis

PURPOSE

Interstitial cystitis/painful bladder syndrome is a chronic bladder inflammatory disease of unknown etiology that is often regarded as neurogenic cystitis. The condition is associated with focal inflammation, urothelial lesions, voiding dysfunction and pain in the pelvic/perineal area. Approximately 90% of patients with the condition are women, suggesting the possibility of hormonal involvement in interstitial cystitis/painful bladder syndrome symptoms. We examined the basis of gender specific pelvic pain in a murine model of neurogenic cystitis that recapitulates features of interstitial cystitis/painful bladder syndrome and in which pelvic pain is mediated by mast cell histamine.

MATERIALS AND METHODS

Murine neurogenic cystitis was induced by tail base inoculation of C57BL/6 or BALB/c mice with the Bartha strain of pseudorabies virus. Pelvic pain behavior was assessed by quantifying tactile allodynia in response to mechanical stimulation with von Frey filaments. Bladder mast cells were quantified by flow cytometry.

RESULTS

Female mice of each genetic background showed significantly greater pelvic pain behavior than males, although responses were greater in BALB/c females. Gender specific pelvic pain behavior did not correspond to increased bladder inflammation or barrier dysfunction. Modulating reproductive hormonal status by ovariectomy and subsequent estrogen replacement had no effect on the magnitude of pseudorabies virus induced pain. The number of mast cells was associated with pelvic pain severity in female mice but it did not correlate with gender specific pelvic pain.

CONCLUSIONS

These data suggest that pelvic pain in mice with murine neurogenic cystitis is mediated by gender specific responsiveness to mast cells while pelvic pain severity is modulated by genetic factors.