直肠内温度变化影响肠易激综合征患者内脏感觉阈值

目的 探讨直肠内温度及压力变化对肠易激综合征(IBS)患者内脏感觉阈值的影响，进一步研究IBS的发病机制。方法 通过直肠球囊内注入空气(压力刺激)、38℃温水、4℃冰水(温度刺激)及脐部放置冰袋加直肠球囊内充气，研究直肠温度和压力变化刺激对初始感觉阈值和排便阈值的影响。结果 (1)直肠球囊内注气后，IBS组患者的初始感觉阈值明显低于对照组，排便阈值差异不明显。IBS组中腹泻型与交替型患者的初始感觉阈值及排便阈值均明显降低；便秘型患者的初始感觉阈值稍低于对照组，排便阈值明显增高。(2)直肠球囊内注入4℃冰水后，除便秘型IBS的排便阈值稍有所增加外，其余患者初始感觉阈值及排便阈值均显著降低，以腹泻型变化最明显。(3)脐部放置冰袋可诱发部分患者产生症状，但对初始感觉阈值和排便阈值无明显影响。结论 直肠温度和压力刺激可明显降低IBS患者的初始感觉阈值和排便阈值，以腹泻型患者最显著。内脏对压力和温度的敏感性增高可能是IBS发病的重要机制之一。     

腹部冷刺激对肠易激综合征患者内脏感觉阈值的影响

目的 探讨腹部冷刺激对肠易激综合征（IBS）患者内脏褡珠影响。方法 通过脐部放置冰袋加直肠球囊内充气（时相性）和直肠球囊内注入冰水，观察46例IBS患者症状变化及直肠初始感觉阈值和排便阈值，并与13例健康人对照。结果 （1）脐部放置冰袋加直肠球囊内充气可诱发部分患者症状的产生，如腹痛、腹部不适等，但对初始感觉阈值和排便阈值无明显影响。（2）直肠球囊内注入冰水后，除便秘型IBS的排便阈值稍有所增加但差异不显著外，其余患者初始感觉阈值及排便阈值均明显低于对照组，以腹泻型变化最明显。结论 腹部冷刺激对IBS患者内脏感觉阈值无明显影响，而直肠内冷刺激可明显降低初始感觉阈值，说明IBS患者感觉过敏并非整体痛阈降低所致，而仅指内脏感觉过敏。     

Visceral hypersensitivity following cold water intake in subjects with irritable bowel syndrome

Background Visceral hypersensitivity has been shown to be present in irritable bowel syndrome (IBS). This study sought to investigate rectal sensitivity and abdominal symptoms in IBS patients before and after 220 ml cold water intake. Methods A total of 60 IBS patients and 18 healthy controls participated in this study. Both the perception thresholds and defecation thresholds to rectal balloon distension were measured. Then, all subjects were asked to drink 220 ml 37°C warm water or 4°C cold water, and these steps were repeated 20 min later. Symptoms including abdominal pain/discomfort, bloating, and diarrhea were recorded during the study. Results Compared with the controls, the thresholds of initial sensation to rectal balloon distention in IBS patients were significantly lower while the defecation thresholds were higher in constipation-predominant IBS patients. After drinking cold water, the perception thresholds in IBS patients and the defecation thresholds in diarrhea-predominant IBS patients were further decreased. However, warm water intake did not change the perception thresholds significantly in either IBS patients or controls. A negative linear correlation was found between the symptoms and the visceral perception thresholds in diarrhea-predominant IBS patients who showed significant symptoms after cold water intake. Conclusion The results indicated that cold water intake leads to lowered visceral perception thresholds in IBS patients that were inversely relevant to the abdominal symptoms in symptomatic diarrhea-predominant IBS patients. The alteration of rectal sensitivity and abdominal symptoms following cold water stimulation provided further objective evidence for visceral hypersensitivity in IBS patients.     

Alterations in cerebral potentials evoked by rectal distention and drinking ice water in patients with irritable bowel syndrome

AIM: Visceral hypersensitivity has been found to be present in irritable bowel syndrome (IBS). The current study sought to study visceral afferent hypersensitivity in IBS patients and obtain further objective evidence of alterations in intestinal afferent pathways in IBS patients by cerebral evoked potentials (CEP). METHOD: We studied 30 female IBS patients and 12 female healthy subjects. Rectal perception thresholds to balloon distention were measured and CEP was recorded in response to rhythmic rectal distention (two distention series, each of 100 repetitions at a frequency of 1 Hz) at the volume of perception thresholds. All subjects were then asked to drink 220 mL 4 degrees C ice water and the above steps were repeated 20 min later. RESULTS: Rectal distention led to recognizable and reproducible CEP. Compared to healthy subjects, IBS patients demonstrated significantly shorter N1, P1 and N2 latencies (P < 0.05). After drinking ice water, IBS patients exhibited further shortened N1, P1 and N2 latencies (P < 0.05), but drinking did not alter the latencies of healthy controls and the amplitudes of both IBS patients and healthy controls. CONCLUSION: The shorter latency of cerebral potentials evoked by rectal distention and ice water stimulation in IBS patients provided further objective evidence for defective visceral afferent transmission in IBS patients.     

Stimulation of the nitric oxide-guanosine 3', 5'-cyclic monophosphate pathway by sildenafil: effect on rectal muscle tone, distensibility, and perception in health and in irritable bowel syndrome

OBJECTIVES: Nitric oxide, a neurotransmitter in the noncholinergic, nonadrenergic nervous system, is a mediator of relaxation of GI smooth muscle and of visceral nociception mainly studied in vitro. Sildenafil stimulates the nitric oxide guanosine 3', 5'-cyclic monophosphate (NO-cGMP) pathway through inhibition of phosphodiesterase 5. The aims of this study were to evaluate in vivo the effect of stimulation of the NO-cGMP pathway on rectal tone, distensibility, and perception in healthy individuals and in patients with irritable bowel syndrome (IBS). METHODS: In eight healthy subjects and four patients with IBS rectal tone, distensibility and perception thresholds were measured with an electronic barostat both before and 60 min after administration of sildenafil (50 mg p.o.). Perception was scored on a graded scale of 0-6. At the end of a distension series an anatomic questionnaire was filled out by the subjects. RESULTS: Sildenafil significantly reduced rectal tone in healthy subjects (intrabag volume predrug: 145.5 +/- 18.7 ml vs postdrug: 164.4 +/- 16.9 ml, p = 0.01) and IBS (111.3 +/- 25.2 ml vs 136.5 +/- 33.3 ml; p = 0.01) but did not alter rectal compliance (healthy subjects: 5.8 +/- 0.4 vs 6.3 +/- 0.6 ml/mm Hg, p > 0.05; IBS subjects: 6.1 +/- 0.6 vs 7.1 +/- 1.0 ml/mm Hg, p > 0.05). Intrabag pressure and rectal wall tension to reach perception thresholds for initial sensation, sensation of stool, and urgency were not altered by sildenafil. However, intrabag volumes to reach these thresholds were significantly increased by sildenafil both in healthy subjects and in patients with IBS. Viscerosomatic referral was unchanged. CONCLUSIONS: Stimulation of the NO-cGMP pathway decreases rectal tone but does not influence rectal distensibility. Relaxation of the rectum is accompanied by an increase in rectal volumes to reach perception thresholds in healthy subjects and in patients with IBS, but no direct effect on rectal perception can be demonstrated.     

Visceral sensitivity and symptoms in patients with constipation- or diarrhea-predominant irritable bowel syndrome (IBS): effect of a low-fat intraduodenal infusion

BACKGROUND: Visceral hypersensitivity is common in Irritable Bowel Syndrome (IBS) patients, and symptoms exacerbate postprandially. Yet the effects of nutrients on visceral sensitivity and symptoms in these patients have not been fully explored. AIMS: To evaluate the differences of visceral sensitivity and symptoms in healthy subjects and IBS patients during fasting and intraduodenal lipids infusion. METHODS: Graded rectal distensions at fixed tension levels were performed in 16 IBS patients (8 IBS-C and 8 IBS-D) and 6 healthy subjects before and during intraduodenal lipids infusion at 0.5 kcal/min. Tension levels were increased in 4 gr increments up to 64 gr or discomfort during both conditions. At each step, perception and symptoms were measured by means of a validated questionnaire. RESULTS: In basal conditions, perception thresholds in IBS patients and health were, respectively, 8 +/- 2 gr versus 32 +/- 9 gr (p < 0.001) with no changes during lipids. Intraduodenal lipids infusion significantly lowered threshold of discomfort in IBS patients in comparison to fasting (24 +/- 6 gr vs 34 +/- 4 gr; p < 0.05), while health tolerated all distension without discomfort. No differences of compliance, perception, or discomfort were observed between the two subgroups of patients at each tension step. The predominant symptom elicited in patients with IBS-C was abdominal pain (54%), while patients with IBS-D exhibited urgency (63%, p < 0.005); this pattern was maintained during lipids. CONCLUSIONS: Intraduodenal lipids increase visceral sensitivity in both IBS-C and IBS-D; symptoms specificity in response to rectal distension is maintained in the postprandial period. Lipids may be responsible for the postprandial symptoms exacerbation in IBS.     

肠易激综合征患者直肠扩张后脑诱发电位的研究

目的 通过比较直肠扩张后脑诱发电位(CEP)的改变,探讨肠易激综合征(IBS)患者内脏高敏感性的发生机制,旨在进一步获得IBS感觉传入通路异常的客观依据。方法 根据罗马Ⅱ标准选择女性IBS患者10例,其中腹泻型6例,便秘型2例,腹泻-便秘交替型2例,另设7例女性健康志愿者为对照组,对其进行直肠气囊扩张,首先测出每例受试者感觉阈值,用1.5倍该阈值空气体积作为刺激(频率1Hz,连续100次,休息10分钟,重复一次),启动并记录两组受试者CEP的变化。结果 直肠节律性机械扩张引出可识别、可复制的CEP。与健康对照者相比,IBS患者N_1,P_1,N_2潜伏期明显缩短(P<0.05),同时,峰间波幅有增大趋势,但无统计学意义(P>0.05)。结论 IBS患者经直肠扩张后产生的CEP的改变证实了其内脏高敏感性及内脏传入通路的异常。     

Effect of a corticotropin releasing hormone receptor antagonist on colonic sensory and motor function in patients with irritable bowel syndrome

BACKGROUND AND AIMS: Corticotropin releasing hormone (CRH) is a major mediator of the stress response in the brain-gut axis. Irritable bowel syndrome (IBS) is presumed to be a disorder of the brain-gut link associated with an exaggerated response to stress. We hypothesised that peripheral administration of alpha-helical CRH (alphahCRH), a non-selective CRH receptor antagonist, would improve gastrointestinal motility, visceral perception, and negative mood in response to gut stimulation in IBS patients. METHODS: Ten normal healthy subjects and 10 IBS patients, diagnosed according to the Rome II criteria, were studied. The tone of the descending colon and intraluminal pressure of the sigmoid colon were measured at baseline, during rectal electrical stimulation (ES), and at recovery after administration of saline. Visceral perception after colonic distension or rectal ES was evaluated as threshold values on an ordinate scale. The same measurements were repeated after administration of alphahCRH (10 micro g/kg). RESULTS: ES induced significantly higher motility indices of the colon in IBS patients compared with controls. This response was significantly suppressed in IBS patients but not in controls after administration of alphahCRH. Administration of alphahCRH induced a significant increase in the barostat bag volume of controls but not in that of IBS patients. alphahCRH significantly reduced the ordinate scale of abdominal pain and anxiety evoked by ES in IBS patients. Plasma adrenocorticotropic hormone and serum cortisol levels were generally not suppressed by alphahCRH. CONCLUSION: Peripheral administration of alphahCRH improves gastrointestinal motility, visceral perception, and negative mood in response to gut stimulation, without affecting the hypothalamo-pituitary-adrenal axis in IBS patients.     

Repetitive rectal painful distention induces rectal hypersensitivity in patients with irritable bowel syndrome

Background A reduced rectal perceptual threshold has been reported in patients with irritable bowel syndrome (IBS), but this phenomenon may be induced by a comorbid psychological state. We evaluated the rectal pain threshold at baseline and after conditioning (repetitive rectal painful distention: RRD) in patients with IBS or functional abdominal pain syndrome (FAPS), which is an abdominal pain disorder, and in healthy controls, and determined whether rectal hypersensitivity is a reliable marker for IBS. Methods The rectal sensory threshold was assessed by a barostat. First, a ramp distention of 40 ml/min was induced, and the threshold of pain and the maximum tolerable pressure (mmHg) were measured. Next, RRD (phasic distentions of 60-s duration separated by 30-s intervals) was given with a tracking method until the subjects had complained of pain six times. Finally, ramp distention was induced again, and the same parameters were measured. The normal value was defined by calculating the 95% confidence intervals of controls. Results Five or six of the seven IBS patients showed a reduced rectal pain threshold or maximum tolerable pressure, respectively, at baseline. In all patients with IBS, both thresholds were reduced after RRD load, but they were reduced in none of the patients with FAPS. RRD significantly reduced both thresholds in the IBS group (P < 0.05), but it had no effect in the control or FAPS groups. Conclusions Rectal hypersensitivity induced by RRD may be a reliable marker for IBS. Conditioning-induced visceral hypersensitivity may play a pathophysiologic role in IBS.     

Effect of a second-generation alpha2delta ligand (pregabalin) on visceral sensation in hypersensitive patients with irritable bowel syndrome

BACKGROUND: Visceral hypersensitivity is an important pathophysiological factor in irritable bowel syndrome (IBS). Pre-clinical studies suggest that the alpha(2)delta ligand pregabalin reduces both visceral allodynia and hyperalgesia, but is inactive on basal sensitivity. AIM: To assess the effect of pregabalin on the perception of rectal distension in hypersensitive IBS patients. METHODS: Twenty-six patients with Rome-II-defined IBS (aged 18-46 years, 7 male) were included in a randomized, double-blind, placebo-controlled, parallel-group study in which they received either 3 weeks oral pregabalin (titrated: 50 mg tid days 1-3, 100 mg tid days 4-7, 150 mg tid days 8-11; fixed 200 mg tid days 12-21 +/-4) or placebo control. Rectal sensitivity was assessed using a barostat technique, in which sensory thresholds were determined using the ascending method of limits, followed by tracking both before and after treatment. Only patients with a pain threshold of 相似文献   

Intrarectal injection of glycerol induces hypersensitivity to rectal distension in healthy subjects without modifying rectal compliance

BACKGROUND: Rectal sensory thresholds are lowered in patients with irritable bowel syndrome (IBS), reflecting visceral hyperlagesia, which might be related to subclinical inflammation. AIM: To evaluate the effects of an intraluminal injection of glycerol, a mucosal irritant, on rectal tone and perception of distension in 12 healthy subjects. METHODS: Rectal tone was evaluated with a barostat. First sensation, need to defecate and pain thresholds were evaluated during isobaric phasic distensions, before and 20 and 120 min after injection of 10 ml glycerol in the rectum. RESULTS: Baseline bag volume (97.9 +/- 56.2 ml) significantly decreased 20 min (49.7 +/- 42.2 ml; P= 0.026) and 120 min (66.5 +/- 38.3 ml; P= 0.050) after injection of glycerol, indicating its hypertonic effect. The pressure defining sensory thresholds was decreased significantly 20 min after glycerol injection: first sensation, 14.6 +/- 2.9 versus 18.3 +/- 7.2 mm Hg (P = 0.01); need to defecate, 19.6 +/- 3.7 versus 26.0 +/- 6.9 mm Hg; pain, 23.8 +/- 4.5 versus 35.6 +/- 9.5 mm Hg (P = 0.001). This effect was maintained for 120 min after injection of glycerol. Slopes of the compliance curves did not differ before and after injection of glycerol. CONCLUSIONS: Intraluminal injection of glycerol significantly increases rectal tone and sensitizes healthy volunteers to rectal distension, since they show significantly lower thresholds after glycerol. This could constitute a model of visceral hypersensitivity in healthy volunteers.     

Novel techniques to study visceral hypersensitivity in irritable bowel syndrome

Visceral hypersensitivity has emerged as a key hypothesis in explaining the painful symptoms of irritable bowel syndrome (IBS), and it has been proposed as a “biologic marker” for the condition. Visceral hypersensitivity can be influenced by peripheral and central mechanisms affecting pain perception. The optimal method for its assessment in humans has not been determined. Current techniques include stimulation via the computerized barostat and electrical stimulation, response measures including the lower limb reflex, and brain imaging modalities such as functional MRI and positron emission tomography. It has been shown that IBS patients have decreased sensory thresholds to colonic and rectal balloon distention by barostat. Studies using electrical stimulation and the RIII lower limb reflex have further confirmed enhanced visceral perception in IBS. Evidence from more recent neuroimaging studies suggests that IBS patients have abnormal activation of brain circuits involved in emotional and cognitive modulation of sensory information, resulting in ineffective pain modulation; these circuits may have a pathophysiologic role in enhancing visceral perception. There are few effective pharmacologic treatments that relieve IBS symptoms, and improved understanding of brain-gut interactions and factors relating to enhanced visceral perception may guide us in developing more efficacious treatments.     

Visceral hypersensitivity in irritable bowel syndrome

Altered central processing, abnormal gastrointestinal motility and visceral hypersensitivity may be possible major pathophysiology of irritable bowel syndrome (IBS). These factors affect each other and are probably associated with development of IBS symptoms. It has been confirmed that lower pain threshold to colonic distention was observed in most of patients with IBS than healthy subjects. We have investigated pain perception of the descending colon among different subtypes of IBS. There was no difference in pain threshold to colonic distention between IBS with diarrhea and constipation. Some brain regions such as the anterior cingulate cortex (ACC) may play a major role for generating pain and/or pain-related emotion in humans. IBS patients showed greater activation in the perigenual ACC during painful rectal distention compared with healthy subjects. Inflammation, stress and the combination of both stimuli can induce significant increase in visceral sensitivity in animal models. Serotonin (5-HT) can modulate visceral perception. It has been thought that 5-HT(3) receptors may play an important role for conveying visceral sensation from the gut. Corticotropin-releasing hormone (CRH) may also modulate visceral pain hypersensitivity in IBS. CRH receptor-1 antagonist significantly prevented an increase in gut sensitivity in rats. It has been demonstrated that non-specific CRH receptor antagonist α-helical CRH significantly reduced abdominal pain score during gut stimulus in patients with IBS. In conclusion, visceral hypersensitivity is common in IBS patients and probably plays a major role in development of the symptoms and both central and peripheral factors may enhance the pain sensitivity.     

Differences in gastric mechanosensory function after repeated ramp distensions in non-consulters with dyspepsia and healthy controls

BACKGROUND: Abnormal visceral mechano-sensory function has been reported in 50% of non-ulcer (functional) dyspepsia patients. However, only a minority of subjects with functional dyspepsia ever seek medical attention. Whether factors promoting health care seeking behaviour explain visceral hypersensitivity is unknown. Decreased rectal thresholds following sigmoid mechanical stimulation have been observed in irritable bowel but this mechanism has not been evaluated in functional dyspepsia. AIMS: To compare visceral mechanosensory function in healthy asymptomatic subjects and non-consulters with chronic unexplained dyspepsia. METHODS: Forty two volunteers were recruited: 10 had a history of chronic or recurrent upper abdominal pain or discomfort as assessed by a standardised questionnaire, and Helicobacter pylori status was determined (ELISA and (13)C urea breath test). Eight H pylori negative, currently asymptomatic dyspeptic subjects who were non-consulters and eight asymptomatic age and sex matched H pylori negative controls were enrolled. With a barostat bag in the proximal part of the stomach, visceral perception thresholds were determined by random tracking. Thereafter, standardised ramp distensions were performed (2 mm Hg increments, duration of each pressure step 30 seconds, maximum pressure 35 mm Hg (or occurrence of pain)) and tracking of sensory thresholds and ramp distension repeated every 30 minutes for a total of two hours. RESULTS: Overall, thresholds for first perception were significantly lower in dyspeptic subjects compared with asymptomatic controls (12.5 (0.6) mm Hg v 17.5 (1.0) mm Hg; p<0.02). After repeated ramp distensions, thresholds for first perception significantly increased by 3.6 (0.7) mm Hg in healthy subjects compared with 0.1 (1.4) mm Hg in subjects with dyspepsia (p<0.05 dyspeptics v controls). CONCLUSIONS: (1) Repeated mechanical stimulation increases visceral sensory thresholds in asymptomatic subjects while thresholds remain unchanged in dyspeptics. (2) Visceral hyperalgesia occurs in dyspeptic subjects who are not health care seekers.     

Pain produced by electric stimulation of the rectum in patients with irritable bowel syndrome: further evidence of visceral hyperalgesia

BACKGROUND: Visceral hyperalgesia is most likely a phenomenon of substantial clinical importance and may also play a role in the pathophysiology of the irritable bowel syndrome (IBS). We investigated the manifestation of visceral hyperalgesia in IBS patients by nociceptive electric stimulation of the rectosigmoid junction and rectum. METHODS: Twelve IBS patients fulfilling the Rome criteria and 9 healthy controls were studied. Visceral single and repeated electric burst stimuli were applied with a bipolar electric stimulator inserted through the sigmoidoscope. The sensation (ST) and pain detection (PDT) thresholds were determined in response to single and repeated stimuli at the rectosigmoid junction, and PDT to repeated stimuli at four different positions in the rectum. Cutaneous single and repeated electric stimuli were applied to the lateral aspect of the foot, determining ST and PDT. RESULTS: Cutaneous stimulation showed no significant differences for ST and PDT between patients and controls. The rectosigmoid junction showed significantly lower ST for single stimuli (P<0.01) and a significantly lower PDT for single and for repeated stimuli (P<0.05 and P<0.02) in IBS patients. In the rectum the IBS patients had a significantly lower PDT than controls (P<0.001). CONCLUSIONS: For cutaneous electric stimulation no differences in the pain thresholds between the two groups were found, showing that there is no generalized hyperalgesia in IBS patients. The IBS patients had a specific decrease of the pain thresholds in the rectum and rectosigmoid junction, indicating visceral hyperalgesia. These results point to central visceral hyperexcitability as an important factor in the pathophysiology of IBS.     

Functional brain imaging in irritable bowel syndrome with rectal balloon－distention by using fMRI

AIM: Irritable bowel syndrome (IBS) is characterized by abdominal pain and changes in stool habits. Visceral hypersensitivity is a key factor in the pathophysiology of IBS. The aim of this study was to examine the effect of rectal balloon-distention stimulus by blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) in visceral pain center and to compare the distribution, extent, and intensity of activated areas between IBS patients and normal controls. METHODS: Twenty-six patients with IBS and eleven normal controls were tested for rectal sensation, and the subjective pain intensity at 90 ml and 120 ml rectal balloon-distention was reported by using Visual Analogue Scale. Then, BOLD-fMRI was performed at 30 ml, 60 ml, 90 ml, and 120 ml rectal balloon-distention in all subjects. RESULTS: Rectal distention stimulation increased the activity of anterior cingulate cortex (35/37), insular cortex (37/37), prefrontal cortex (37/37), and thalamus (35/37) in most cases. At 120 ml of rectal balloon-distention, the activation area and percentage change in MR signal intensity of the regions of interest (ROI) at IC, PFC, and THAL were significantly greater in patients with IBS than that in controls. Score of pain sensation at 90 ml and 120 ml rectal balloon-distention was significantly higher in patients with IBS than that in controls. CONCLUSION: Using fMRI, some patients with IBS can be detected having visceral hypersensitivity in response to painful rectal balloon-distention. fMRI is an objective brain imaging technique to measure the change in regional cerebral activation more precisely. In this study, IC and PFC of the IBS patients were the major loci of the CNS processing of visceral perception.     

Sensitivity disturbances in patients with irritable bowel syndrome and fibromyalgia

BACKGROUND: Although visceral hypersensitivity is a common feature among patients with irritable bowel syndrome (IBS), studies on somatic sensitivity have given controversial results. AIM: To assess visceral sensitivity in response to isotonic rectal distensions and somatic sensitivity at different layers of the body wall (skin, subcutis, and muscle) in patients with IBS and fibromyalgia (FM), within and outside the area of abdominal pain referral. MATERIALS AND METHODS: We studied 10 patients with IBS, 5 patients with FM, 9 patients with IBS+FM, and 9 healthy controls. Rectal distensions were performed by increasing tension at 4 g steps up to 64 g or discomfort. Pain thresholds to electrical stimulation were measured within and outside the areas of abdominal pain referral. RESULTS: Patients with IBS and IBS+FM demonstrated rectal hypersensitivity in comparison to controls. The threshold of discomfort was 44 +/- 5 g in IBS and 36 +/- 5 in IBS+FM patients, while patients with FM and healthy controls tolerated all distensions without discomfort. In the areas of pain referral, pain thresholds of all three tissues of the body wall were lower than normal in all patients groups (p < 0.001). In control areas, the pain thresholds were normal in skin, and lower than normal in subcutis and muscle in IBS (p < 0.001). FM and IBS+FM demonstrated somatic hypersensitivity at all sites (p < 0.001 vs healthy). CONCLUSION: Our observations seem to indicate that, although sharing a common hypersensitivity background, multiple mechanisms may modulate perceptual somatic and visceral responses in patients with IBS and FM.     

Pain Produced by Electric Stimulation of the Rectum in Patients with Irritable Bowel Syndrome: Further Evidence of Visceral Hyperalgesia

Background: Visceral hyperalgesia is most likely a phenomenon of substantial clinical importance and may also play a role in the pathophysiology of the irritable bowel syndrome (IBS). We investigated the manifestation of visceral hyperalgesia in IBS patients by nociceptive electric stimulation of the rectosigmoid junction and rectum. Methods: Twelve IBS patients fulfilling the Rome criteria and 9 healthy controls were studied. Visceral single and repeated electric burst stimuli were applied with a bipolar electric stimulator inserted through the sigmoidoscope. The sensation (ST) and pain detection (PDT) thresholds were determined in response to single and repeated stimuli at the rectosigmoid junction, and PDT to repeated stimuli at four different positions in the rectum. Cutaneous single and repeated electric stimuli were applied to the lateral aspect of the foot, determining ST and PDT. Results: Cutaneous stimulation showed no significant differences for ST and PDT between patients and controls. The rectosigmoid junction showed significantly lower ST for single stimuli (P &lt; 0.01) and a significantly lower PDT for single and for repeated stimuli (P &lt; 0.05 and P &lt; 0.02) in IBS patients. In the rectum the IBS patients had a significantly lower PDT than controls (P &lt; 0.001). Conclusions: For cutaneous electric stimulation no differences in the pain thresholds between the two groups were found, showing that there is no generalized hyperalgesia in IBS patients. The IBS patients had a specific decrease of the pain thresholds in the rectum and rectosigmoid junction, indicating visceral hyperalgesia. These results point to central visceral hyperexcitability as an important factor in the pathophysiology of IBS.     

Gender-related differences in visceral perception in health and irritable bowel syndrome

BACKGROUND: Irritable bowel syndrome (IBS) is more common in female subjects, and IBS patients generally exhibit reduced pain thresholds to rectal distension. The aim of the present paper was to determine gender-related differences in rectal perception in both healthy controls and IBS patients. METHODS: Fifty-nine IBS patients (age 20-65 years; mean, 39.2 years; 31 women, 28 men) with symptoms that fulfilled Rome-II criteria and 21 healthy controls (age 25-58 years; mean, 37.8 years; 11 women, 10 men) were recruited. Participants completed a questionnaire regarding bowel symptoms and psychological distress, and maximal tolerable pressures were evaluated via barostat tests. RESULTS: Although healthy women appear to have lower perception thresholds than men, significant gender differences in pain sensitivity were not detected (P > 0.05). In addition, female patients with IBS also exhibited no enhanced colorectal perception, as compared with male IBS patients (P > 0.05). CONCLUSIONS: No gender differences in visceral perception were determined to exist between the healthy controls and the IBS patients. Therefore, the increased prevalence of IBS in women may be related to another set of pathophysiological factors, and not to gender-related differences in visceroperception.     

一氧化氮能神经调节异常在腹泻型肠易激综合征患者中的作用

目的　探讨一氧化氮 (NO)在肠易激综合征 (IBS)发病机制中的作用 ,并从基因水平揭示NO含量改变的原因。方法　 (1)应用电子气压泵及灌注导管测压仪研究 2 5例腹泻型IBS患者及 15例正常志愿者的肛门、直肠压力、直肠顺应性、乙状结肠和直肠运动指数以及直肠对容量刺激的感觉阈值 ;(2 )应用硝酸还原酶法测定两组肠黏膜NO的含量 ;(3)NADPH黄递酶组化法和计算机图像分析系统对两组肠黏膜肌层一氧化氮合酶 (NOS)阳性神经纤维作定量分析 ;(4)采用荧光定量PCR(FQ PCR)方法对神经型一氧化氮合酶 (nNOS)的基因表达进行定量分析。结果　 (1)肠道测压 :IBS患者的直肠静息压、肛管上部静息压、收缩压、松弛压、肛管下部静息压、收缩压、松弛压和直肠顺应性与正常人比较 ,差异无显著性 (P >0 .0 5 ) ;患者乙状结肠和直肠运动指数明显高于正常人 (P <0 .0 5 ) ;(2 )直肠内脏感觉阈值 :最低感觉阈值、排便阈值和疼痛阈值明显低于正常人 (P <0 .0 5 ) ;(3)肠黏膜NO含量 :患者结肠黏膜NO含量显著低于正常人 ,并且患者的NO含量与运动指数成负相关 ,与感觉阈值、排便阈值、疼痛阈值呈正相关 (P <0 .0 5 ) ;(4)NADPH组化染色 :IBS患者黏膜肌层NOS阳性神经纤维的面积和平均吸光度较正常人显著减少 (P <0 .0 5 ) ;(5 )NOS mRNA