Colonic Irritation Research Articles

T1781 The Role of TRPA1 in Visceral Hypersensitivity Arising from Neonatal Colon Irritation

T1781 The Role of TRPA1 in Visceral Hypersensitivity Arising from Neonatal Colon Irritation

Colon mustard oil instillation induced cross-organ reflex sensitization on the pelvic–urethra reflex activity in rats

We investigated the participation of cyclin-dependent kinase-5 (Cdk5)-mediated N-methyl- d-aspartate receptor (NMDAR) NR2B subunit phosphorylation in cross-organ reflex sensitization caused by colon irritation. The external urethral sphincter electromyogram (EUSE) reflex activity evoked by the pelvic afferent nerve test stimulation (TS, 1 stimulation/30 s) and protein expression in the spinal cord and dorsal root ganglion tissue (T13-L2 and L6-S2 ipsilateral to the stimulation) in response to colon mustard oil (MO) instillation were tested in anesthetized rats. When compared with a baseline reflex activity with a single action potential evoked by the TS before the administration of test agents, MO instillation into the descending colon sensitized the evoked activity characterized by elongated firing in the reflex activity in association with increased protein levels of Cdk5, PSD95, and phosphorylated NR2B (pNR2B) but not of total NR2B (tNR2B) in the spinal cord tissue. Both cross-organ reflex sensitization and increments in protein expression were reversed by intra-colonic pretreatments with ruthenium red (a non-selective transient receptor potential vanilloid, TRPV, antagonist), capsaizepine (a TRPV 1-selective antagonist), lidocaine (a nerve conduction blocker) as well as by the intra-thecal pretreatment with APV (a NRMDR antagonist) Co-101244 (a NR2B-selective antagonist) and roscovitine (a Cdk5 antagonist). Moreover, compared with the control group, both the increase in pNR2B and the cross-organ reflex sensitization were attenuated in the si-RNA of NR2B rats. All these results suggested that Cdk-dependent NMDAR NR2B subunit phosphorylation mediates the development of cross-organ pelvic–urethra reflex sensitization caused by acute colon irritation which could possibly underlie the high concurrence of pelvic pain syndrome with irritable bowel syndrome.

Oral Cyclic Guanosine Monophosphate (cGMP) Desensitizes Colonic Afferents in an Animal Model of Experimental Colitis

Purpose: Irritable bowel syndrome (IBS) is characterized by lower abdominal pain and/or discomfort in association with alterations in intestinal motility. Visceral afferent sensitization is thought to play a key role. Linaclotide, a novel, orally-administered agonist of guanylate cyclase-C receptors (GC-C) markedly increases intracellular and extracellular cGMP levels. Furthermore, linaclotide decreases visceral pain in animal models and reduced pain in an IBS-constipation study. To better understand these analgesic effects, we examined whether cGMP decreases pelvic afferent activity. The aim of this study was to explore the antinociceptive effects of cGMP in an animal model of colonic afferent sensitization. Methods: Colonic sensitization was produced in female Sprague-Dawley rats by intra-rectal administration of trinitrobenzesulfonic acid (TNBS). Responses of colonic afferents to colonic distension (CD), capsaicin (CP, 0.1–5.0 μg), and Substance P (SP, 0.1–10 μg) were tested before and 30 min after intra-duodenal administration of cGMP (30 mg/kg) either 1 hour (N = 8) or 8–10 days post-TNBS (N = 8) and were compared to intra-rectal saline controls (N = 12). Afferent activity was recorded in fibers sensitive to CD and CP from the fine bundles of the right pelvic nerve. Resting activity represented maximal activity recorded 1 min before each intervention. Changes in afferent activity calculated as number of impulses per minute were expressed as percent change from the resting firing rate. Results: In intra-rectal saline controls, cGMP slightly increased baseline afferent firing rates but had no effect on the afferent response to CD or CP. The increase in afferent firing rates produced by SP, however, was significantly attenuated by cGMP (148 ± 34% vs. 989 ± 391%, P < 0.05). One hour after colonic irritation, basal afferent activity was increased and not affected by cGMP; their responses to CD, CP (493 ± 233% vs. 1846 ± 569%, P < 0.05), and SP (267 ± 65% vs. 964 ± 294%, P < 0.05), however, were all significantly attenuated. Afferent responses to CD (>30 mmHg) and cGMP measured 8–10 days after TNBS were similar to those recorded acutely. Afferent responses to SP were significantly reduced by cGMP 8–10 days after TNBS (255 ± 63% vs. 455 ± 58%, P < 0.05), while responses trended towards normalization in response to CP. Conclusion: Oral cGMP reduced the response of sensitized pelvic afferent neurons in rats to different stimuli, particularly those chemically responsive to SP. These findings suggest that the production and secretion of cGMP elicited by oral linaclotide may explain the activity of linaclotide on visceral pain. Additional studies are needed to further characterize the role of cGMP in attenuating afferent responses to noxious stimuli.

RETRACTED: Repeated electro-acupuncture attenuates chronic visceral hypersensitivity and spinal cord NMDA receptor phosphorylation in a rat irritable bowel syndrome model

Acupuncture has been used in clinical trials for the treatment of abdominal pain in patients with irritable bowel syndrome (IBS). However, scientific evidence is still lacking and the underlying mechanism remains largely unexplored. The aim of this study was to examine the effects of repeated administration of electro-acupuncture (EA) on chronic visceral hypersensitivity and on the phosphorylation of spinal cord N-methyl-D-aspartic acid (NMDA) receptors in a rat model of IBS. The results showed that repeated administration of EA at bilateral points of Zu-san-li (ST-36) and Shang-ju-xu (ST-37) significantly attenuated chronic visceral hypersensitivity induced in young adult rats by neonatal colon irritation. Such an effect was not seen in either of the two controls: sham-EA at ST-36 and ST-37 without electrical stimulation and EA at control points (BL-62 and tail). Furthermore, rats with chronic visceral hypersensitivity exhibited high-level expression of phosphorylated NMDA receptor subunit 1 (pNR1) in the spinal cord (L4-L5 segments), which was markedly attenuated by EA treatment. In addition, EA at ST-36 and ST-37 neither altered the pain threshold of normal rats nor affected the expression of pNR1 in the lumbosacral spinal cord. Altogether, these data indicate that the EA-mediated attenuation of chronic visceral hypersensitivity is correlated with the down-regulation of NMDA receptors phosphorylation at the spinal level.

Altered behavior and digestive outcomes in adult male rats primed with minimal colon pain as neonates

BackgroundNeonatal colon irritation (CI; pain or inflammation) given for 2 weeks prior to postnatal day 22 (PND22), causes long-lasting functional disorders in rats that can be seen 6 months after the initial insult. This study looked at the effect of varying the frequency and duration of neonatal CI on the rate of growth, digestive outcomes, exploratory activity, and colon and skin sensitivity in adult rats.MethodsMale Sprague-Dawley rats were given CI using repeated colorectal distension (CRD) at different time intervals and for varying durations starting at PND 8, 10 or 14. Control rats were handled by the investigator without any intracolonic insertion. Further experiments were done on adult rats. Digestive outcomes (food and water consumption, fecal and urinary outputs) were measured using metabolic cages. Exploratory behavior was measured using digital video tracking in an open field. Cutaneous sensitivity was assessed by measuring the responses to mechanical and heat stimuli applied to the shaved abdomen or hind paws. Visceral sensitivity was measured by recording electromyographic responses, under light isoflurane anesthesia, from the external oblique muscles in response to CRD.ResultsNo significant weight differences were observed between CI and control rats. Exploratory behavior was reduced in rats with neonatal CI compared to control. Digestive outputs and somatic and visceral sensitivity changed between different treatment groups with earlier and more frequent insults yielding a higher deviation from normal.ConclusionThe diversity of behavioral and digestive symptoms in these rats parallels the diversity of symptoms in patients with functional gastrointestinal disorders and is consistent with global plastic changes affecting more than one system in the organism.

Assessment of colon sensitivity by luminal distension in mice

Colorectal distension (CRD) is a widely used and reliable method for evaluating colon sensitivity in unanesthetized animals, including humans. Hollow organ distension is a mechanical stimulus that replicates in humans the sensation and pattern of referral of their visceral pain. In animals, CRD has been employed to evaluate drug efficacy, strain, sex or genetic differences and changes in colon sensitivity after inflammation or irritation of the distal colon. Responses to CRD are measured as electromyographic (EMG) recordings of the abdominal musculature, termed the visceromotor response. This protocol will provide sufficient detail to allow an investigator to surgically prepare a mouse for CRD, construct distending balloons, distend the colon, and accumulate and analyze data from EMG recordings; examples are also provided to illustrate typical experimental outcomes. CRD recording sessions are typically 2 h in duration.

New Insights in the Etiology and Pathophysiology of Irritable Bowel Syndrome: Contribution of Neonatal Stress Models

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, characterized by abdominal pain and disturbed defecation that cannot be explained by structural abnormalities. Although IBS symptoms (visceral pain, increased gut permeability, motility alterations) are clearly established, the etiology of this pathology is loosely understood. Nevertheless, clinical studies have reported that some early abuse (physical and psychological) is often associated with IBS development. Thus, loss and separation in the family during childhood may contribute to the IBS development. The recent development of animal models has pointed out the importance of early traumatic experiences in favoring the occurrence of IBS in adult life. Among these different models, neonatal maternal deprivation (NMD), neonatal colonic irritation (inflammatory stimuli), and neonatal colonic pain (rectal distension) have been described to mimic some cardinal features of IBS. The purpose of this review is 3-fold. First, to present the different neonatal stress models. Second, to review the literature on the influence of these early traumatic experiences on the gastrointestinal tract disturbances observed in adult life. Finally, we will also present the mediators and mechanisms involved in gut dysfunction triggered by NMD and probably in IBS.

Enhanced expression of mast cell growth factor and mast cell activation in the bladder following the resolution of trinitrobenzenesulfonic acid (TNBS) colitis in female rats

Chronic pelvic pain disorders often overlap. We have shown that acute colonic irritation can produce acute irritative micturition patterns and acutely sensitize bladder afferent responses to mechanical and chemical stimuli. We hypothesize that with time, colonic irritation can lead to neurogenic changes in the bladder and the development of chronic bladder sensitization. Micturition patterns were measured in rats 60-90 days after the induction of trinitrobenzenesulfonic acid (TNBS) colitis in the resolution phase of this model. Total and activated mast cells (MCs) were quantified in the bladder, while mRNA levels of stem cell factor (SCF; a.k.a. MC growth factor) and nerve growth factor (NGF; a MC and nociceptive C-fiber stimulator) were quantified in the bladder and L6-S1 dorsal root ganglia (DRG). Following intra-rectal TNBS, voiding volume was reduced (P < 0.005), while voiding frequency was increased (P < 0.05), both by approximately 50%. Furthermore, both the percentage and density of activated bladder MCs were significantly elevated (P < 0.05), although total MC counts were not statistically increased. At the molecular level, urinary bladder SCF expression increased twofold (P < 0.005), as did NGF (P < 0.01), while L6-S1 DRG levels were not significantly elevated. Chronic cystitis in the rat as evidenced by changes in micturition patterns and the recruitment of activated MCs can occur during the resolution phase of TNBS colitis. These changes, of which MCs may play an important role, appear to be maintained over time and may occur via stimulation of convergent pelvic afferent input resulting in the upregulation of neurotrophic factors in the target organ.

Colonic irritation

Colonic irritation

The Vanilloid Receptor Initiates and Maintains Colonic Hypersensitivity Induced by Neonatal Colon Irritation in Rats

Robust chemical or mechanical irritation of the colon of neonatal rats leads to chronic visceral hypersensitivity. The clinical and physiologic relevance of such noxious stimulation in the context of human irritable bowel syndrome is questionable. The aims of this study were to determine whether mild chemical irritation of the colon of neonatal rats produced persistent changes in visceral sensitivity and to evaluate the role of transient receptor potential vanilloid 1 (TRPV1) in the initiation and maintenance of visceral hypersensitivity. Ten-day-old rat pups received an intracolonic infusion of 0.5% acetic acid in saline. TRPV1 inhibitors were administered 30 minutes before acetic acid sensitization. Sensitivity of the colon to balloon distention (CRD) in adults was measured by grading their abdominal withdrawal reflex and electromyographic responses. In adult rats, TRPV1 antagonist was injected intraperitoneally 30 minutes before CRD. Neonatal acetic acid treatment resulted in higher sensitivity to CRD in adult rats compared with controls in the absence of histopathologic signs of inflammation. Treatment of colons of adult rats with acetic acid did not produce persistent sensitization. Antagonism of the TRPV1 before neonatal administration of acetic acid and after established visceral hypersensitivity attenuated sensitivity to CRD. TRPV1 expression was increased in dorsal root ganglia-containing colon afferent neurons. We have described a new model for persistent colonic sensory dysfunction following a transient noxious stimulus in the neonatal period and a potentially important role for TRPV1 in initiation and maintenance of persistent visceral hypersensitivity.

Microglia: a newly discovered role in visceral hypersensitivity?

Given the growing body of evidence for a role of glia in pain modulation, it is plausible that the exaggerated visceral pain in chronic conditions might be regulated by glial activation. In this study, we have investigated a possible role for microglia in rats with chronic visceral hypersensitivity and previously documented altered neuronal function. Experiments were performed on adult male Sprague-Dawley rats pre-treated with neonatal colon irritation (CI) and on control rats. Effects of fractalkine (FKN, a chemokine involved in neuron-to-microglia signaling) and of minocycline (an inhibitor of microglia) on visceral sensitivity were examined. Visceral sensitivity was assessed by recording the electromyographic (EMG) responses to graded colorectal distension (CRD) in mildly sedated rats. Responses to CRD were recorded before and after injection of FKN, minocycline or vehicle. Somatic thermal hyperalgesia was measured by latency of paw withdrawal to radiant heat. The pattern and intensity of microglial distribution at L6-S2 in the spinal cord was also compared in rats with CI and controls by fluorescence microscopy using OX-42. Results show that: (1) FKN significantly facilitated EMG responses to noxious CRD by >52% in control rats. FKN also induced thermal hyperalgesia in control rats, consistent with previous reports; (2) minocycline significantly inhibited EMG responses to noxious CRD by >70% in rats with CI compared to controls 60 min after injection. The anti-nociceptive effect of minocycline lasted for 180 min in rats with CI, reaching peak values 60 min after injection. Our results show that FKN enhances visceral and somatic nociception, whereas minocycline inhibits visceral hypersensitivity in chronically sensitized rats, which indicates a role for microglia in visceral hypersensitivity.

Sensitization of pelvic nerve afferents and mast cell infiltration in the urinary bladder following chronic colonic irritation is mediated by neuropeptides

Irritable bowel syndrome and interstitial cystitis frequently overlap. We have shown that acute colitis sensitizes urinary bladder afferents to both mechanical and chemical stimuli and that chronic colitis similarly produces neurogenic cystitis. We hypothesize that chronic irritation of the colon releases neuropeptides from bladder afferents, leading to receptor sensitization and neurogenic inflammation. Female Sprague-Dawley rats received intrarectal trinitrobenzenesulfonic acid (TNBS) or vehicle 3 days following either systemic capsaicin (CP) pretreatment or vehicle. Ten days later, action potentials of single-unit pelvic C-fiber afferents with receptive fields in the bladder were recorded under urethane anesthesia during graded bladder distensions (UBD) or intravesical capsaicin (vCP) administration. In controls, UBD increased bladder afferent firing in proportion to intravesical pressure. At intravesical pressures of 30 mmHg and above, the percent increase in afferent firing was significantly accentuated following TNBS compared with controls (1,222 +/- 176 vs. 624 +/- 54%, P < 0.01). The response to vCP was also enhanced (4,126 +/- 775 vs. 1,979 +/- 438%, P < 0.01). Systemic depletion of neuropeptides from sensory nerves abolished these effects. Histological examination of the bladders revealed an increase in mast cell density in TNBS-treated animals compared with controls (18.02 +/- 1.25 vs. 3.11 +/- 0.27 mast cells/x100 field, P < 0.01). This effect was significantly ameliorated with CP (10.25 +/- 0.95, P < 0.5 vs. TNBS-treated animals). In summary, chronic colonic irritation in the rat sensitizes urinary bladder afferents to noxious stimuli and causes mast cell infiltration in the bladder. Depletion of neuropeptides from sensory afferents diminishes these effects, suggesting they play an important role.

196: Colonic Irritation in the Rat Sensitizes Urinary Bladder Afferents to Mechanical and Chemical Stimuli: A Role of Local Cross-Organ Afferent Reflexes in the Overlap of Chronic Pelvic Pain Disorders

196: Colonic Irritation in the Rat Sensitizes Urinary Bladder Afferents to Mechanical and Chemical Stimuli: A Role of Local Cross-Organ Afferent Reflexes in the Overlap of Chronic Pelvic Pain Disorders

Pharmacological and Pharmacokinetic Aspects of Functional Gastrointestinal Disorders

Medications are commonly used for the treatment of patients with functional gastrointestinal disorders. The general goal of this report is to review the pharmacokinetics and pharmacology of medications used in functional gastrointestinal disorders. Methods included literature review, consensus evaluation of the evidence for each topic assigned originally to 1 or 2 authors, and broader review at a harmonization session as part of the Rome III process. This report reviews the animal models that have been validated for the study of effects of pharmacologic agents on sensation and motility; the preclinical pharmacology, pharmacokinetics, and toxicology usually required for introduction of novel therapeutic agents; the biomarkers validated for studies of sensation and motility end points with experimental medications in humans; the pharmacogenomics applied to these medications and disorders; and the pharmacology of agents that are applied or have potential for treatment of functional gastrointestinal disorders, including psychopharmacologic agents. Clinician and basic investigators involved in the treatment or investigation of functional gastrointestinal disorders or disease models need to have a comprehensive understanding of a vast range of medications. It is anticipated that the interaction between investigators of basic science, basic and applied pharmacology, and clinical trials will lead to better treatment of these disorders.

Fundamentals of Neurogastroenterology: Basic Science

The focus of neurogastroenterology in Rome II was the enteric nervous system (ENS). To avoid duplication with Rome II, only advances in ENS neurobiology after Rome II are reviewed together with stronger emphasis on interactions of the brain, spinal cord, and the gut in terms of relevance for abdominal pain and disordered gastrointestinal function. A committee with expertise in selective aspects of neurogastroenterology was invited to evaluate the literature and provide a consensus overview of the Fundamentals of Neurogastroenterology textbook as they relate to functional gastrointestinal disorders (FGIDs). This review is an abbreviated version of a fuller account that appears in the forthcoming book, Rome III. This report reviews current basic science understanding of visceral sensation and its modulation by inflammation and stress and advances in the neurophysiology of the ENS. Many of the concepts are derived from animal studies in which the physiologic mechanisms underlying visceral sensitivity and neural control of motility, secretion, and blood flow are examined. Impact of inflammation and stress in experimental models relative to FGIDs is reviewed as is human brain imaging, which provides a means for translating basic science to understanding FGID symptoms. Investigative evidence and emerging concepts implicate dysfunction in the nervous system as a significant factor underlying patient symptoms in FGIDs. Continued focus on neurogastroenterologic factors that underlie the development of symptoms will lead to mechanistic understanding that is expected to directly benefit the large contingent of patients and care-givers who deal with FGIDs.

Colonic irritation in the rat sensitizes urinary bladder afferents to mechanical and chemical stimuli: an afferent origin of pelvic organ cross-sensitization

Chronic pelvic pain (CPP) disorders frequently overlap. We have demonstrated that acute and chronic colonic irritation can lead to neurogenic cystitis. We hypothesize that acute colonic irritation can sensitize urinary bladder afferents to mechanical and chemical stimuli. Single-unit afferent activity was recorded from fine filaments of the pelvic nerve in urethane-anesthetized Sprague-Dawley female rats before and 1 h after intracolonic administration of trinitrobenzenesulfonic acid (TNBS). Only spontaneously active afferents with receptive fields in the bladder and conduction velocities <2.5 m/s (unmyelinated C-fibers) were studied. Mechanical sensitivity was tested by bladder distension (BD) during saline infusion, whereas chemical sensitivity was tested with intravesical capsaicin, bradykinin, or substance P. Colonic irritation increased the resting firing rate of bladder afferents twofold (1.0 +/- 0.2 vs. 0.49 +/- 0.2 impulses/s, P < 0.05). Moreover, at low-pressure BDs (10-20 mmHg), a greater percentage of afferents exhibited increased activity following TNBS (73 vs. 27%, P < 0.05). Although the magnitude of the afferent response to BD was unchanged at low pressures, the response was greatly enhanced at pressures 30 mmHg and above (2.36 +/- 0.56 vs. 8.55 +/- 0.73 impulses/s, P < 0.05). Responses to capsaicin, bradykinin, and substance P were also significantly enhanced following TNBS, and all responses were blocked by bladder denervation. In rats, colonic irritation sensitizes urinary bladder afferents to noxious mechanical and chemical stimuli. Interruption of the neural input to the bladder minimized this effect, suggesting a local afferent pathway from the colon. Thus, the overlap of CPP disorders may be a consequence of pelvic afferent cross-sensitization.

A Model of Neural Cross-Talk and Irritation in the Pelvis: Implications for the Overlap of Chronic Pelvic Pain Disorders

Irritable bowel syndrome, interstitial cystitis, and other chronic pelvic pain (CPP) disorders often occur concomitantly. Neural cross-talk may play a role in the overlap of CPP disorders via the convergence of pelvic afferents. We investigated the hypothesis that afferent irritation of one pelvic organ may adversely influence and sensitize another via neural interactions. We measured pelvic organ smooth muscle and striated muscle reflexes during micturition and colorectal distention (CRD) in urethane-anesthetized rats. The effects of acute cystitis on distal colonic sensory thresholds to CRD and the effects of acute colonic irritation on micturition parameters were assessed. External urethral sphincter (EUS) electromyography (EMG) was typical for the rat, with phasic firing during micturition. External anal sphincter EMG also showed phasic firing during micturition in synchrony with EUS activity but, in addition, showed both tonic bursts and phasic firing independent of EUS activity. Before bladder irritation, graded CRDs to 40 cm H2O produced no notable changes in abdominal wall EMG activity. Following acute bladder irritation, dramatic increases in abdominal wall EMG activity in response to CRD were observed at much lower distention pressures, indicating colonic afferent sensitization. Analogously, following acute colonic irritation, bladder contraction frequency increased 66%, suggesting sensitization of lower urinary tract afferents. We report compelling evidence of bidirectional cross-sensitization of the colon and lower urinary tract in a novel experimental model. This cross-sensitization may account for the substantial overlap of CPP disorders; however, further studies are needed to fully characterize these pathways.

Differential effects of glutamate receptor antagonists on dorsal horn neurons responding to colorectal distension in a neonatal colon irritation rat model

To investigate and compare the effects of spinal D-(-)-2-amino-7-phosphonoheptanoic acid (AP-7) and 6-cyano-7-nitroquinoxaline-2,3-dione disodium (CNQX), two glutamate receptor antagonists, on the responses of dorsal horn neurons to colorectal distension (CRD) in adult rats exposed to neonatal colon irritation (CI). Hypersensitive SD rats were generated by CI during postnatal days 8, 10 and 12. Experiments on adult rats were performed using extracellular single-unit recording. The effects of spinal application of AP-7 (0.001, 0.01, 0.1, 1 mmoL) were tested on the CRD-evoked neuronal responses in 16 controls and 17 CI rats. The effects of CNQX (0.2, 2, 5, 10 micromoL) were also tested on the CRD-evoked responses of 17 controls and 18 CI neurons. (1) The average responses of lumbosacral neurons to all intensities of CRD in CI rats were significantly higher than those in control rats; (2) In control rats, AP-7 (0.01 mmoL) had no significant effect on the neuronal response to all intensities of CRD (20, 40, 60, 80 mmHg); while AP-7 (0.1 mmoL) inhibited the neuronal response to 80-mmHg CRD. By contrast, in CI rats, AP-7 (0.01-1 mmoL) attenuated the CRD-evoked neuronal responses to all distention pressures in a dose-dependent manner; (3) In control rats, CNQX (2 micromoL) had no significantly effect on the neuronal response to all intensities of CRD; however, CNQX (5 micromoL) significantly attenuated the responses to CRD in the 40-80 mmHg range. By contrast, CNQX (2-10 micromoL) significantly decreased the neuronal responses in CI rats to non-noxious and noxious CRD in a dose-dependent manner. Our results suggest that spinal N-methyl-D-aspartate (NMDA) and non-NMDA receptors may contribute to the processing of central sensitivity in a neonatal CI rat model, but they may play different roles in it.

Randomized double-blind placebo-controlled trial of balsalazide in the prevention of acute radiation enteritis as a consequence of pelvic radiotherapy

Acute radiation enteritis (ARE) is a common complication in pelvic radiotherapy (RT) patients. Manifested as diarrhea, tenesmus, abdominopelvic pain, and peri-rectal discomfort, ARE results largely from irritation of the sigmoid colon and rectum by RT. Even with highly conformal techniques, sparing these structures may be difficult. Thus, interventions to limit ARE have broad applicability and potential to enhance patients’ quality of life. 5-amino-salicylates (5-ASA) are traditionally used to treat inflammatory bowel disease. All but one prior attempt at using 5-ASA to prevent ARE have failed. We sought to evaluate balsalazide (BSZ), a new 5-ASA agent, for its potential to prevent or limit ARE in patients receiving RT for prostate or cervical cancer. BSZ has unique advantages: its delivery system yields higher concentrations of active 5-ASA in the distal colon and rectum than other agents, and it lacks the antigenic sulfa moiety present in sulfasalazine, the only other 5-ASA with demonstrated benefit in this setting. Thus, we considered it an ideal candidate for preventing or limiting ARE. Informed consent was obtained prior to entry into this IRB-approved study. The accrual goal was 100 patients, 50 in each arm. Eligible patients included those treated for FIGO stage IB2-IVA cervical cancer, AJCC Stage T1-3 M0 prostate cancer, or biochemical failure after prostatectomy. RT was delivered in a 4-field technique to at least 45 Gy, and tumor dose was at least 64 Gy for prostate patients or 75 Gy for cervical patients. Brachytherapy boost was permitted. Other criteria were age 18 years or older and KPS above 70% Patients were given 2250 mg of BSZ or an identical-appearing placebo twice daily beginning 5 days prior to RT, and continuing for 2 weeks after completion. Toxicities were graded weekly according to NCI Common Toxicity Criteria for each of the following: proctitis, diarrhea, dysuria, weight loss, fatigue, nausea, and vomiting. A symptom index was formulated for each toxicity consisting of the toxicity’s numeric grade multiplied by the number of days it was experienced, and summed for each grade. Thus, a patient with 7 days of grade 1 proctitis, 14 days of grade 2 proctitis, and 7 days of grade 3 proctitis [(1*7)+(2*14)+(3*7)] would have a proctitis index of 56. A higher index indicates worse toxicity. Except nausea/vomiting, seen in 2 patients on BSZ and 1 on placebo, all toxicities were appreciably lower in patients taking BSZ. Proctitis was prevented most effectively, with a mean index of 35 in BSZ patients vs. 77 in placebo patients (p = 0.04). No patient on BSZ experienced grade 4 diarrhea, while 2 placebo patients did. Average weight loss in placebo patients was greater than 3 lbs., whereas average BSZ patients gained weight. Fatigue index in BSZ patients was 20, while placebo patients averaged 49. Unexpectedly, dysuria was appreciably lower in BSZ patients as well. BSZ is a new-generation 5-ASA drug with significant potential to prevent or reduce symptoms of ARE in patients undergoing pelvic RT. We feel that our pilot study justifies the formation of a cooperative group trial to assess its efficacy in a multi-institutional setting.

Randomized double-blind placebo-controlled trial of balsalazide in the prevention of acute radiation enteritis as a consequence of pelvic radiotherapy

Acute radiation enteritis (ARE) is a common complication in pelvic radiotherapy (RT) patients. Manifested as diarrhea, tenesmus, abdominopelvic pain, and peri-rectal discomfort, ARE results largely from irritation of the sigmoid colon and rectum by RT. Even with highly conformal techniques, sparing these structures may be difficult. Thus, interventions to limit ARE have broad applicability and potential to enhance patients’ quality of life. 5-amino-salicylates (5-ASA) are traditionally used to treat inflammatory bowel disease.