Antinociceptive effect of berberine on visceral hypersensitivity in rats

AIM: To assess the protective effect of berberine administration and the role of nitric oxide (NO) in visceral hypersensitivity. METHODS: Fifty male Sprague-Dawley rats were randomly assigned to five groups. An inflammatory bowel disease model was induced in rats by intracolonic instillation of 1 mL 4% acetic acid at 8 cm proximal to the anus for 30 s and restraint stress. After subsidence of inflammation on day 7 of the experiment, the rats were subjected to rectal distension, performed by a balloon (6-Fr, 2 mm external diameter, disposable silicon balloon-urethral catheter for pediatric use) which was rapidly inflated with increasing volumes of prewarmed (37 ℃) water (0.1, 0.2, 0.3, 0.4, 0.6, 0.8 and 1 mL) for 30 s at four-minute intervals, and then the abdominal withdrawal reflex (AWR) and the level of fecal output were measured, respectively. AWR scores either 0, 1, 2, 3 or 4 were obtained by blinded observers. Rats had been pretreated with berberine or aminoguanidine (NO synthetase inhibitor) or berberine + aminoguanidine before measurement. RESULTS: The rats in the placebo group showed a hypersensitive response to rectal distension (2.69 ± 0.08 vs 1.52 ± 0.08, P = 0.000) and defecated more frequently than those in the control group (5.0 ± 0.16 vs 0.44 ± 0.16, P = 0.000). Comparing the berberine with placebo group, the AWR scores were reduced for all distension volumes and were significant at 0.2-1 mL (1.90 ± 0.08 vs 2.69 ± 0.08, P = 0.000), while the numbers of hard pellets, soft pellets, formless stools, and total fecal output in the placebo group were significantly larger than in the berberine group (5.0 ± 0.16 vs 2.56 ± 0.16, P = 0.000). Administration of aminoguanidine or berberine + aminoguanidine before VH score measurement reversed the antinociceptive effect of berberine (2.52 ± 0.08 vs 1.90 ± 0.08, P = 0.000; 2.50 ± 0.08 vs 1.90 ± 0.08, P = 0.000). The numbers of hard pellets, soft pellets, formless stool, and total of fecal output in aminoguanidine group were significantly larger tha     

Increased expression of brain-derived neurotrophic factor is correlated with visceral hypersensitivity in patients with diarrheapredominant irritable bowel syndrome

BACKGROUND Visceral hypersensitivity is considered to play a vital role in the pathogenesis of irritable bowel syndrome(IBS). Neurotrophins have drawn much attention in IBS recently. Brain-derived neurotrophic factor(BDNF) was found to mediate visceral hypersensitivity via facilitating sensory nerve growth in pre-clinical studies. We hypothesized that BDNF might play a role in the pathogenesis of diarrhea-predominant IBS(IBS-D).AIM To investigate BDNF levels in IBS-D patients and its role in IBS-D pathophysiology.METHODS Thirty-one IBS-D patients meeting the Rome IV diagnostic criteria and 20 ageand sex-matched healthy controls were recruited. Clinical and psychological assessments were first conducted using standardized questionnaires. Visceral sensitivity to rectal distension was tested using a high-resolution manometry system. Colonoscopic examination was performed and four mucosal pinch biopsies were taken from the rectosigmoid junction. Mucosal BDNF expression and nerve fiber density were analyzed using immunohistochemistry. Mucosal BDNF mRNA levels were quantified by quantitative real-time polymerase chain reaction. Correlations between these parameters were examined.RESULTS The patients had a higher anxiety score [median(interquartile range), 6.0(2.0-10.0) vs 3.0(1.0-4.0), P = 0.003] and visceral sensitivity index score [54.0(44.0-61.0)vs 21.0(17.3-30.0), P < 0.001] than controls. The defecating sensation threshold[60.0(44.0-80.0) vs 80.0(61.0-100.0), P = 0.009], maximum tolerable threshold[103.0(90.0-128.0) vs 182.0(142.5-209.3), P < 0.001] and rectoanal inhibitory reflex threshold [30.0(20.0-30.0) vs 30.0(30.0-47.5), P = 0.032] were significantly lower in IBS-D patients. Intestinal mucosal BDNF protein [3.46 E-2(3.06 E-2-4.44 E-2) vs3.07 E-2(2.91 E-2-3.48 E-2), P = 0.031] and mRNA [1.57(1.31-2.61) vs 1.09(0.74-1.42), P = 0.001] expression and nerve fiber density [4.12 E-2(3.07 E-2-7.46 E-2) vs1.98 E-2(1.21 E-2-4.25 E-2), P = 0.002] were significantly elevated in the patients.Increased BDNF expression was positively correlated with abdominal pain and disease severity and negatively correlated with visceral sensitivity parameters.CONCLUSION Elevated mucosal BDNF may participate in the pathogenesis of IBS-D via facilitating mucosal nerve growth and increasing visceral sensitivity.     

Electroacupuncture alleviates stress-induced visceral hypersensitivity through an opioid system in rats

AIM:To investigate whether stress-induced visceral hypersensitivity could be alleviated by electroacupuncture(EA) and whether EA effect was mediated by endogenous opiates.METHODS:Six to nine week-old male SpragueDawley rats were used in this study.Visceral hypersensitivity was induced by a 9-d heterotypic intermittent stress(HIS) protocol composed of 3 randomly stressors,which included cold restraint stress at 4?℃ for 45 min,water avoidance stress for 60 min,and forced swimming stress for 20 min,in adult male rats.The extent of visceral hypersensitivity was quantified by electromyography or by abdominal withdrawal reflex(AWR) scores of colorectal distension at different distention pressures(20 mmHg,40 mmHg,60 mmHg and 80 mmHg).AWR scores either 0,1,2,3 or 4 were obtained by a blinded observer.EA or sham EA was performed at classical acupoint ST-36(Zu-San-Li) or BL-43(Gao-Huang) in both hindlimbs of rats for 30 min.Naloxone(NLX) or NLX methiodide(m-NLX) was administered intraperitoneally to HIS rats in some experiments.RESULTS:HIS rats displayed an increased sensitivity to colorectal distention,which started from 6 h(the first measurement),maintained for 24 h,and AWR scores returned to basal levels at 48 h and 7 d after HIS compared to pre-HIS baseline at different distention pressures.The AWR scores before HIS were 0.6 ± 0.2,1.3 ± 0.2,1.9 ± 0.2 and 2.3 ± 0.2 for 20 mmHg,40 mmHg,60 mmHg and 80 mmHg distention pressures,respectively.Six hours after termination of the last stressor,the AWR scores were 2.0 ± 0.1,2.5 ± 0.1,2.8 ± 0.2 and 3.5 ± 0.2 for 20 mmHg,40 mmHg,60 mmHg and 80 mmHg distention pressures,respectively.EA given at classical acupoint ST-36 in both hindlimbs for 30 min significantly attenuated the hypersensitive responses to colorectal distention in HIS rats compared with sham EA treatment [AWRs at 20 mmHg:2.0 ± 0.2 vs 0.7 ± 0.1,P = 4.23 711 E-4;AWRs at 40 mmHg:2.6 ± 0.2 vs 1.5 ± 0.2,P = 0.00 163;AWRs at 60 mmHg:3.1 ± 0.2 vs 1.9 ± 0.1,P = 0.003;AWRs at 80 mmHg:3.6 ± 0.1 vs 2.4 ± 0.2,P = 0.0023;electromyographic(EMG) at 20 mmHg:24 ± 4.7 vs 13.8 ± 3.5;EMG at 40 mmHg:60.2 ± 6.6 vs 30 ± 4.9,P = 0.00 523;EMG at 60 mmHg:83 ± 10 vs 39.8 ± 5.9,P = 0.00 029;EMG at 80 mmHg:94.3 ± 10.8 vs 49.6 ± 5.9,P = 0.00 021].In addition,EA at the acupuncture point BL-43 with same parameters did not alleviate visceral hypersensitivity in HIS rats.EA in healthy rats also did not have any effect on AWR scores to colorectal distention at distention pressuresof 20 and 40 mmHg.The EA-mediated analgesic effect was blocked by pretreatment with NLX in HIS rats [AWR scores pretreated with NLX vs normal saline(NS) were 2.0 vs 0.70 ± 0.20,2.80 ± 0.12 vs 1.50 ± 0.27,3 vs 2.00 ± 0.15 and 3.60 ± 0.18 vs 2.60 ± 0.18 for 20 mmHg,40 mmHg,60 mmHg and 80 mmHg;P = 0.0087,0.0104,0.0117 and 0.0188 for 20,40,60 and 80 mmHg,respectively].Furthermore,EA-mediated analgesic effect was completely reversed by administration of m-NLX,a peripherally restricted opioid antagonist(EMG pretreated with m-NLX vs NS were 30.84 ± 4.39 vs 13.33 ± 3.88,74.16 ± 9.04 vs 36.28 ± 8.01,96.45 ± 11.80 vs 50.19 ± 8.28,and 111.59 ± 13.79 vs 56.42 ± 8.43 for 20 mmHg,40 mmHg,60 mmHg and 80 mmHg;P = 0.05 026,0.00 034,0.00 005,0.000 007 for 20 mmHg,40 mmHg,60 mmHg and 80 mmHg,respectively).CONCLUSION:EA given at classical acupoint ST-36 alleviates stress-induced visceral pain,which is most likely mediated by opioid pathways in the periphery.     

肠易激综合征内脏感觉过敏动物模型的建立

目的 内脏感觉过敏是肠易激综合征(IBS)的主要发病机制之一，本文利用大鼠建立一种内脏感觉过敏的动物模型。方法8～21天雌雄Wistar大鼠每天接受不同压力的结肠机械刺激，成年后直肠扩张时记录大鼠腹肌收缩反应(AWR)评分，并进行降结肠的组织学检查。结果 ①新生儿时期接受不同压力结肠机械刺激的大鼠成年后直肠扩张时AWR评分明显高于对照组，不同压力机械刺激组间AWR评分无明显差异，雌性大鼠AWR评分明显高于雄性大鼠。②各组大鼠降结肠常规病理切片未见明显异常。结论 Wistar大鼠在新生儿时期接受的结肠刺激可造成无明显病理改变的慢性内脏感觉过敏模型，雌性大鼠更具有易感性。     

大鼠肠道高敏性模型的建立及其内脏敏感性评估

目的　内脏高敏感性是肠易激综合征 (IBS)的重要病理生理特征之一 ,该文旨在建立内脏高敏性动物模型 ,并用两种方法验证该模型的有效性。方法　取出生后 8～ 2 1d的大鼠 ,每天给予直肠内醋酸刺激 ,分别在出生后 6、8及 10周 ,对这些成年后的大鼠进行直肠扩张 ,评估其腹部收缩反射(AWR)阈值 ;并在出生 12周后测定大鼠腹壁肌电活动 ,验证敏感性有无异常改变。结果　与新生期生理盐水刺激组 (NS组 )和成年醋酸刺激组 (AA组 )相比 ,直肠扩张时 ,新生期醋酸刺激组大鼠 (NA组 )腹部抬高和背部拱起的容量阈值显著降低 (P值均 <0 .0 1) ;0 .5、0 .8、1.2ml扩张容量下腹壁肌电活动明显增强 (P分别 <0 .0 1,<0 .0 5和 0 .0 5 )。结论　新生期肠道内的慢性刺激 ,可以在成年后引起慢性内脏敏感性增高 ,而肠黏膜未见异常病理改变 ,符合IBS的基本特征。     

Role of nesfatin-1 in a rat model of visceral hypersensitivity

AIM: To explore the role of nesfatin-1 on irritable bowel syndrome (IBS)-like visceral hypersensitivity. METHODS: The animal model of IBS-like visceral hypersensitivity was induced by intracolonic infusion of 0.5% acetic acid (AA) in saline once daily from postnatal days 8-21. Experiments were performed when rats became adults. The visceral sensitivity of rats was evaluated by abdominal withdrawal reflex (AWR) and electromyographic (EMG) activity of the external oblique muscle to graded colorectal distension. The content of nesfatin-1 in serum was determined using enzyme-linked immunosorbent assay. After implantation of an intracerebroventricular (ICV) cannula and two electrodes into the external oblique muscle, model rats were randomly divided into four groups. Animals then received ICV injection of 8 μg of anti-nesfatin-1/ nucleobindin-2 (NUCB2), 50 μg of α-helical cortico-tropin releasing factor (CRF) 9-41 (non-selective CRF receptor antagonist), 50 μg of NBI-27914 (selective CRF1 receptor antagonist) or 5 μL of vehicle. After 1 h of ICV administration, visceral sensitivity of each group was measured again, and comparisons between groups were made. RESULTS: Rats treated with AA showed higher mean AWR scores and EMG activity at all distension pressures compared with controls (P < 0.05). On histopathologic examination, no evidence of inflammation or abnormalities in structure were noted in the colon of either control or AA-treated groups. Myeloperoxidase values were not significantly different between the two groups. The level of nesfatin-1 in serum was significantly higher in the AA-treated group than in the control group (5.34 ± 0.37 ng/mL vs 4.81 ± 0.42 ng/mL, P < 0.01). Compared with rats injected with vehicle, rats which received ICV anti-nesfatin-1/NUCB2, α-helical CRF9-41 or NBI-27914 showed decreased mean AWR scores and EMG activity at all distension pressures (P < 0.05). CONCLUSION: Nesfatin-1 may be associated with IBS-like visceral hypersensitivity, which may be implicated in brain C     

肥大细胞在应激所致大鼠直肠高敏感性中的作用

目的　内脏高敏感性是肠易激综合征 (IBS)最重要的特征之一 ,精神因素可能与IBS发生有关。本研究旨在探讨急性精神应激对大鼠直肠敏感性的效应以及肥大细胞的可能作用。方法　通过对大鼠施加 2h的轻度束缚建立应激模型 ,以腹壁肌电活动评估它对直肠内气囊扩张的反应性 ,并取结肠标本进行肥大细胞计数 ,通过P物质刺激结肠体外释放组胺 ,研究肥大细胞的活化情况。此外 ,还进行了急性应激对躯体感觉和结肠转运效应的研究。结果　与假应激组相比 ,在 0 .5、0 .8及 1.2ml扩张容量下 ,轻度束缚应激使大鼠对直肠扩张的敏感性显著增强 (P <0 .0 1)。与假应激组相比 ,应激组大鼠P物质体外诱导的组胺释放明显增加 [分别为 (6 .4 5± 2 .6 9)和 (10 .71± 3.91)nmol/g组织 ,P <0 .0 5 ],而结肠肥大细胞计数无明显差异 [分别为 (2 .6 8± 0 .90 )和 (2 .79± 0 .75 ) /高倍视野 ,P >0 .0 5 ]。急性应激也加速结肠转运 ,并引起躯体痛觉缺失。结论　应激可显著增强大鼠直肠敏感性 ,肥大细胞活化可能在外周参与了这一致敏过程     

卵巢激素对慢性内脏高敏感大鼠结肠组织5-HT3受体的影响

目的 在慢性高敏感大鼠模型上构建去卵巢模型，观察大鼠结肠组织5-HT3受体在雌激素不同水平的变化，探讨卵巢激素对IBS发病的影响。方法 选取新生SD雌鼠，在其发育的8．21天给予结直肠球囊扩张刺激，建立慢性内脏高敏感雌鼠模型，待其发育至2月大小将雌鼠随机分为3组：假手术(sham)组、去卵巢(ovx)组、去卵巢加雌激素和孕激素(ovx E2 P)组，每组16只，处理4周后对其内脏敏感性进行行为学评估(AWR评估)，观察各组大鼠玻璃小球排出情况；并采用RT-PCR及免疫组织化学SP法检测大鼠肠道5-HL受体的变化。结果 ovx E2 P组大鼠腹部抬起及拱背抬高压力值明显低于sham组和ovx组；ovx E2 P组大鼠排便量增多，玻璃小球排出时间短于sham组和ovx组；ovx E， P组5-HB受体水平最高，ovx组受体水平最低。结论 卵巢激素促进结肠组织5-HT3受体的表达，加重内脏高敏感性。     

Effects of electroacupuncture on corticotropin-releasing hormone in rats with chronic visceral hypersensitivity

AIM: To investigate the effect of electroacupuncture on corticotropin-releasing hormone (CRH) in the colon, spinal cord, and hypothalamus of rats with chronic visceral hypersensitivity.METHODS: A rat model of chronic visceral hypersensitivity was generated according to the internationally accepted method of colorectal balloon dilatation. In the 7^th week after the procedure, rats were randomly divided into a model group (MG), electroacupuncture group (EA), and sham electroacupuncture group (S-EA). After treatment, the abdominal withdrawal reflex (AWR) score was used to assess the behavioral response of visceral hyperalgesia. Immunohistochemistry (EnVision method), ELISA, and fluorescence quantitative PCR methods were applied to detect the expression of CRH protein and mRNA in the colon, spinal cord, and hypothalamus.RESULTS: The sensitivity of the rats to the colorectal distension stimulus applied at different strengths (20-80 mmHg) increased with increasing stimulus strength, resulting in increasing AWR scores in each group. Compared with NG, the AWR score of MG was significantly increased (P < 0.01). After conducting EA, the AWR scores of the rats were decreased compared with MG rats. The relative expression of CRH mRNA in the colon, spinal cord, and hypothalamus of MG rats was significantly increased compared with NG rats (P < 0.01). CRH mRNA in the colon and spinal cord of EA and S-EA rats was decreased to varying degrees (P > 0.05) compared with normal rats (NG). However, the decrease in EA compared with MG rats was statistically significant (P < 0.01). The average optical density of CRH expression in the colon of the MG rats was significantly enhanced compared with NG (P < 0.05), while the average optical density of CRH expression in the EA and S-EA rats was significantly decreased compared with MG rats (P < 0.01, P < 0.05, respectively). Compared with MG rats, the CRH concentration in the spinal cord of EA rats was significantly reduced (P < 0.01), but there was no significant change in S-EA rats (P > 0.05).CONCLUSION: Electroacupuncture at the Shangjuxu acupoint was able to significantly reduce the visceral hypersensitivity in rats, and regulated the expression of CRH protein and mRNA in the colon, spinal cord and hypothalamus at different levels, playing a therapeutic role in this model of irritable bowel syndrome.     

Epidermal growth factor upregulates serotonin transporter and its association with visceral hypersensitivity in irritable bowel syndrome

AIM: To investigate the role of epidermal growth factor (EGF) in visceral hypersensitivity and its effect on the serotonin transporter (SERT).METHODS: A rat model for visceral hypersensitivity was established by intra-colonic infusion of 0.5% acetic acid in 10-d-old Sprague-Dawley rats. The visceral sensitivity was assessed by observing the abdominal withdrawal reflex and recording electromyographic activity of the external oblique muscle in response to colorectal distension. An enzyme-linked immunosorbent assay was used to measure the EGF levels in plasma and colonic tissues. SERT mRNA expression was detected by real-time PCR while protein level was determined by Western blot. The correlation between EGF and SERT levels in colon tissues was analyzed by Pearson’s correlation analysis. SERT function was examined by tritiated serotonin (5-HT) uptake experiments. Rat intestinal epithelial cells (IEC-6) were used to examine the EGF regulatory effect on SERT expression and function via the EGF receptor (EGFR).RESULTS: EGF levels were significantly lower in the rats with visceral hypersensitivity as measured in plasma (2.639 ± 0.107 ng/mL vs 4.066 ± 0.573 ng/mL, P < 0.01) and in colonic tissue (3.244 ± 0.135 ng/100 mg vs 3.582 ± 0.197 ng/100 mg colon tissue, P < 0.01) compared with controls. Moreover, the EGF levels were positively correlated with SERT levels (r = 0.820, P < 0.01). EGF displayed dose- and time-dependent increased SERT gene expressions in IEC-6 cells. An EGFR kinase inhibitor inhibited the effect of EGF on SERT gene upregulation. SERT activity was enhanced following treatment with EGF (592.908 ± 31.515 fmol/min per milligram vs 316.789 ± 85.652 fmol/min per milligram protein, P < 0.05) and blocked by the EGFR kinase inhibitor in IEC-6 cells (590.274 ± 25.954 fmol/min per milligram vs 367.834 ± 120.307 fmol/min per milligram protein, P < 0.05).CONCLUSION: A decrease in EGF levels may contribute to the formation of visceral hypersensitivity through downregulation of SERT-mediated 5-HT uptake into enterocytes.     

焦虑大鼠内脏敏感性增高以及行直结肠扩张后血清皮质酮的变化及意义

目的内脏高敏感性是肠易激综合征( 1BS)症状最重要的病理生理机制之一,焦虑可能与内脏高敏的发生密切相关。本研究旨在探讨焦虑对大鼠直结肠敏感性的作用以及血清皮质酮与内脏高敏的关系。方法Wistar大鼠随机分为对照组和焦虑组两组,通过对大鼠行空瓶刺激2周建立以焦虑为主要表现的慢性情绪应激模型。造模期间,观察大鼠的攻击、探究和修饰三种行为,对其进行情绪性行为学分析。造模结束后,以腹部回缩反射(AWR)评分为指标观察大鼠对直结肠气囊扩张(CRD)的反应性,评估内脏敏感性。然后将两组各随机分为扩张组和非扩张组,对扩张组行CRD ,并取血清,对血清皮质酮定量测定。结果空瓶刺激期间,同对照组相比,焦虑组探究、攻击行为明显增多,修饰行为减少(P <0 0 1)。焦虑组在2 0mmHg、40mmHg、60mmHg和80mmHg的扩张压力下的AWR评分均显著高于对照组(P <0 0 1)。焦虑组与对照组相比血清皮质酮水平明显升高(P <0 0 1) ,但各组扩张后皮质酮水平较扩张前仅有轻微升高,无显著差异(P >0 0 5 )。结论焦虑对IBS内脏高敏起一定作用,其发挥作用的机制可能并非单一通过下丘脑_垂体_肾上腺皮质系统(HPA轴)来实现,推测还可能与脑内单胺类神经递质NE浓度的改变有关。     

TLR4 upregulates CBS expression through NF-κB activation in a rat model of irritable bowel syndrome with chronic visceral hypersensitivity

AIM: To investigate the roles of toll-like receptor 4 (TLR4) and nuclear factor (NF)-κB on cystathionine β synthetase (CBS) expression and visceral hypersensitivity in rats.METHODS: This study used 1-7-wk-old male Sprague-Dawley rats. Western blot analysis was employed to measure the expression of TLR4, NF-κB and the endogenous hydrogen sulfide-producing enzyme CBS in colon dorsal root ganglia (DRG) from control and “irritable bowel syndrome” rats induced by neonatal colonic inflammation (NCI). Colon-specific DRG neurons were labeled with Dil and acutely dissociated to measure excitability with patch-clamp techniques. Immunofluorescence was employed to determine the co-expression of TLR4, NF-κB and CBS in DiI-labeled DRG neurons.RESULTS: NCI significantly upregulated the expression of TLR4 in colon-related DRGs (0.34 ± 0.12 vs 0.72 ± 0.02 for the control and NCI groups, respectively, P < 0.05). Intrathecal administration of the TLR4-selective inhibitor CLI-095 significantly enhanced the colorectal distention threshold of NCI rats. CLI-095 treatment also markedly reversed the hyperexcitability of colon-specific DRG neurons and reduced the expression of CBS (1.7 ± 0.1 vs 1.1 ± 0.04, P < 0.05) and of the NF-κB subunit p65 (0.8 ± 0.1 vs 0.5 ± 0.1, P < 0.05). Furthermore, the NF-κB-selective inhibitor pyrrolidine dithiocarbamate (PDTC) significantly reduced the upregulation of CBS (1.0 ± 0.1 vs 0.6 ± 0.1, P < 0.05) and attenuated visceral hypersensitivity in the NCI rats. In vitro, incubation of cultured DRG neurons with the TLR4 agonist lipopolysaccharide significantly enhanced the expression of p65 (control vs 8 h: 0.9 ± 0.1 vs 1.3 ± 0.1; control vs 12 h: 0.9 ± 0.1 vs 1.3 ± 0.1, P < 0.05; control vs 24 h: 0.9 ± 0.1 vs 1.6 ± 0.1, P < 0.01) and CBS (control vs 12 h: 1.0 ± 0.1 vs 2.2 ± 0.4; control vs 24 h: 1.0 ± 0.1 vs 2.6 ± 0.1, P < 0.05), whereas the inhibition of p65 via pre-incubation with PDTC significantly reversed the upregulation of CBS expression (1.2 ± 0.1 vs 0.6 ± 0.0, P < 0.01).CONCLUSION: Our results suggest that the activation of TLR4 by NCI upregulates CBS expression, which is mediated by the NF-κB signaling pathway, thus contributing to visceral hypersensitivity.     

直肠内不同温度刺激对肠易激综合征患者内脏敏感性的影响

目的研究肠易激综合征（IBS）患者对直肠内冷、温两种不同温度扩张试验的反应，以探讨IBS的可能发病机制。方法门诊随机选择腹泻型IBS（D—IBS）21例，便秘型IBS（C—IBS）15例，对照者33例，随机应用冷刺激（3℃水）或温刺激（35℃水）进行球囊灌注扩张，记录诱发受试对象产生便意和腹痛时的球囊内容量及压力。结果①无论予以冷、温何种刺激，D—IBS患者及C—IBS患者便意容量阈值（DSVT）及腹痛容量阈值（APVT）较对照者均明显降低，其中在D—IBS患者又稍低于C—IBS患者，但两者之间无显著性差异；而两种刺激下虽然在D—IBS患者及C—IBS患者中便意压力阈值（DSPT）及腹痛压力阈值（APPT）均较对照者稍低，但三者之间无显著性差异。②在D—IBS患者中，予以冷刺激后患者便意容量阈值（DSVT）及便意压力阈值（DSPT）均较温刺激时明显升高，而对于腹痛容量阈值（APVT）及腹痛压力阈值（APPT）影响不明显；在C—IBS患者中，予以冷刺激后，患者便意容量阈值（DSVT）明显升高，但便意压力阈值（DSPT）无明显变化，而对于腹痛容量阈值（APVT）及腹痛压力阈值（APPT）影响不明显；在对照者中，虽然予以冷刺激后便意及腹痛容量及压力阈值均较温刺激时稍高，但均无统计学差异。③IBS患者较对照者的容量／压力比值普遍降低，但D-IBS组与C—IBS组两者之间无显著性差异；在IBS患者中，无论D—IBS还是C—IBS，予以冷刺激后。诱发患者产生便意所需的球囊内容量／压力比值明显升高，而对于腹痛的产生影响不明显；在对照者两种温度刺激诱发出受试对象产生便意及腹痛的球囊内容量／压力比值均无统计学差异。结论①IBS患者较对照者的内脏敏感性明显增高。②直肠内温度变化对IBS患者的非伤害性内脏感觉的产生有显著的影响，而对伤害性内脏感觉的产生影响不明显。③IBS患者的直肠顺应性减低。     

神经生长因子在大鼠结直肠内脏高敏感形成中的作用

目的 探讨在大鼠结直肠内脏高敏感形成中,神经生长因子所起的作用.方法 以注射神经生长因子+假避水应激(N组,8只)和注射神经生长因子+慢性避水应激(NW组,8只)方法处理大鼠,建立内脏高敏感动物模型,以腹腔注射0.9%氯化钠溶液+假避水应激处理大鼠作为正常对照(C组,8只).造模前后检测结直肠扩张(CRD)后大鼠内脏运动反射变化程度并进行统计学分析.结果 大鼠分组处理前,CRD后内脏运动反射值(WMR值)均差异无统计学意义(P＞0.05).分组处理后,N组和NW组大鼠在CRD压力为20、40和60 mmHg(1 mmHg=0.133 kPa)时,VMR值与C组比较差异均无统计学意义(P＞0.05);而在CRD压力为80 mmHg时,NW组大鼠VMR值(3.54)与C组(2.12)比较差异有统计学意义(P=0.016);而N组大鼠在此压力下VMR值(2.62)虽较C有所升高,但差异无统计学意义(P＞0.05).结论 在应激状态下,应用神经生长因子可明显促进大鼠结直肠内脏高敏感形成.     

Visceral hypersensitivity in inflammatory bowel diseases and irritable bowel syndrome: The role of proteases

Proteases, enzymes catalyzing the hydrolysis of peptide bonds, are present at high concentrations in the gastrointestinal tract. Besides their well-known role in the digestive process, they also function as signaling molecules through the activation of protease-activated receptors(PARs). Based on their chemical mechanism for catalysis, proteases can be classified into several classes: serine, cysteine, aspartic, metallo- and threonine proteases represent the mammalian protease families. In particular, the class of serine proteases will play a significant role in this review. In the last decades, proteases have been suggested to play a key role in the pathogenesis of visceral hypersensitivity, which is a major factor contributing to abdominal pain in patients with inflammatory bowel diseases and/or irritable bowel syndrome. So far, only a few preclinical animal studies have investigated the effect of protease inhibitors specifically on visceral sensitivity while their effect on inflammation is described in more detail. In our accompanying review we describe their effect on gastrointestinal permeability. On account of their promising results in the field of visceral hypersensitivity, further research is warranted. The aim of this review is to give an overview on the concept of visceral hypersensitivity as well as on the physiological and pathophysiological functions of proteases herein.     

Altered profiles of fecal metabolites correlate with visceral hypersensitivity and may contribute to symptom severity of diarrhea-predominant irritable bowel syndrome

BACKGROUND Fecal metabolites are associated with gut visceral sensitivity, mucosal immune function and intestinal barrier function, all of which have critical roles in the pathogenesis of irritable bowel syndrome(IBS). However, the metabolic profile and pathophysiology of IBS are still unclear. We hypothesized that altered profiles of fecal metabolites might be involved in the pathogenesis of IBS with predominant diarrhea(IBS-D).AIM To investigate the fecal metabolite composition and the role of metabolites in IBSD pathophysiology.METHODS Thirty IBS-D patients and 15 age-and sex-matched healthy controls(HCs)underwent clinical and psychological assessments, including the IBS Symptom Severity System(IBS-SSS), an Italian modified version of the Bowel Disease Questionnaire, the Bristol Stool Form Scale(BSFS), the Hospital Anxiety and Depression Scale, and the Visceral Sensitivity Index. Visceral sensitivity to rectal distension was tested using high-resolution manometry system by the same investigator. Fecal metabolites, including amino acids and organic acids, weremeasured by targeted metabolomics approaches. Correlation analyses between these parameters were performed.RESULTS The patients presented with increased stool water content, more psychological symptoms and increased visceral hypersensitivity compared with the controls. In fecal metabolites, His [IBS-D: 0.0642(0.0388, 0.1484), HC: 0.2636(0.0780, 0.3966), P= 0.012], Ala [IBS-D: 0.5095(0.2826, 0.9183), HC: 1.0118(0.6135, 1.4335), P = 0.041],Tyr [IBS-D: 0.1024(0.0173, 0.4527), HC: 0.5665(0.2436, 1.3447), P = 0.018], Phe[IBS-D: 0.1511(0.0775, 0.3248), HC: 0.3967(0.1388, 0.7550), P = 0.028], and Trp[IBS-D: 0.0323(0.0001, 0.0826), HC: 0.0834(0.0170, 0.1759), P = 0.046] were decreased in IBS-D patients, but isohexanoate [IBS-D: 0.0127(0.0060, 0.0246), HC:0.0070(0.0023, 0.0106), P = 0.028] was significantly increased. Only Tyr was mildly correlated with BSFS scores in all subjects(r =-0.347, P = 0.019). A possible potential biomarker panel was identified to correlate with IBS-SSS score(R2 Adjusted= 0.693, P 0.001). In this regression model, the levels of Tyr, Val, hexanoate,fumarate, and pyruvate were significantly associated with the symptom severity of IBS-D. Furthermore, visceral sensation, including abdominal pain and visceral hypersensitivity, was correlated with isovalerate, valerate and isohexanoate.CONCLUSION Altered profiles of fecal metabolites may be one of the origins or exacerbating factors of symptoms in IBS-D via increasing visceral sensitivity.     

ZD 7288,an HCN channel blocker,attenuates chronic visceral pain in irritable bowel syndrome-like rats

AIM:To investigate the effects of ZD 7288,a hyperpolarization-activated cyclic nucleotide-gated(HCN)channel blocker,on rats with chronic visceral pain.METHODS:Rats with visceral hypersensitivity were generated using neonatal colon irritation during postnatal days 8-15 as described previously.Visceral hypersensitivity was evaluated using electromyographic(EMG)responses of abdominal external oblique muscles to 20-80 mmHg colorectal distentions(CRD).Abdominal withdrawal reflex(AWR)scores and pain thresholds were also detected in adult rats.Different doses of ZD7288(25,50,and 100 nmol/L)were intrathecally administered in rats to study the role of spinal HCN channel in chronic visceral hypersensitivity.RESULTS:EMG responses to 20-80 mmHg CRD and AWR scores under 20-60 mmHg CRD significantly increased in rats with visceral hypersensitivity compared to control rats(P<0.05).The pain threshold in rats with visceral hypersensitivity significantly decreased compared to control rats(P<0.05).Treatment with50-100 nmol/L ZD 7288 significantly inhibited EMG responses(16%-62%,80-20 mmHg CRD,P<0.05)and AWR scores(24%-37%,40-20 mmHg CRD,P<0.05;12%-61%,80-20 mmHg CRD,P<0.05,respectively),and significantly increased pain thresholds(32%-77%,P<0.05).CONCLUSION:Spinal HCN channels may play an important role in chronic visceral hypersensitivity.     

大鼠结肠慢性炎性刺激诱导腰骶髓和延髓Fos的表达及其意义

目的　探讨实验性大鼠结肠慢性炎性刺激诱导腰骶髓和延髓中Fos的表达及其意义。方法　成年雄性SD大鼠 ,实验组 (n =1 6 )予三硝基苯磺酸 (TNBS)灌肠诱导结肠炎 ,实验对照组 (n =8)予生理盐水灌肠 ,空白对照组 (n =2 )不予任何刺激 ;分别在灌肠后 3、7、1 4和 2 8d ,采用免疫组化法观察实验组大鼠腰骶髓和延髓中Fos阳性神经元的数量和分布 ,并与对照组进行比较。结果　TNBS灌肠诱导Fos表达多数分布在脊髓背角深层 (Ⅲ～Ⅳ和Ⅴ～Ⅵ层 )和由孤束核、腹外侧区及网状结构形成的延髓内脏带中。TNBS灌肠后 3d ,脊髓和延髓中Fos表达无明显增多。灌肠后 7和 1 4d ,脊髓和延髓中Fos表达明显多于实验对照组 (P <0 .0 5 )。灌肠后 2 8d ,延髓中Fos表达下降 ,与对照组无明显差异 ,部分大鼠脊髓中Fos阳性神经元数 (5 4 .1± 1 6 .3)仍明显多于对照组 (1 2 .2± 2 .6 ,P <0 .0 5 )。结论　脊髓Fos阳性神经元可能在结肠慢性炎性刺激引起的内脏高敏感性中起作用 ,而延髓可能不是内脏高敏感性形成的主要部位。     

Thermal hypersensitivity in a subset of irritable bowel syndrome patients

AIM： To characterize thermal hypersensitivity in patients with constipation- and diarrhea-predominant irritable bowel syndrome （IBS）.
METHODS： Thermal pain sensitivity was tested among patients with diarrhea-predominant IBS （D-IBS） and constipation-predominant IBS （C-IBS） compared to healthy subjects. A total of 42 patients （29 female and 13 male; mean age 27.0 ＋ 6.4 years） with D-IBS; 24 patients （16 female and eight male; mean age 32.5 ：1：8.8 years） with C-IBS; and 52 control subjects （34 female and 18 male; mean age 27.3 ± 8.0 years） participated in the study. Thermal stimuli were delivered using a Medoc Thermal Sensory Analyzer with a 3 cm × 3 cm surface area. Heat pain threshold （HPTh） and heat pain tolerance （HPTo） were assessed on the left ventral forearm and left calf using an ascending method of limits. The Functional Bowel Disease Severity Index （FBDSI） was also obtained for all subjects.
RESULTS： Controls were less sensitive than C-IBS and D-IBS （both at P 〈 0.001） with no differences between C-IBS and D-IBS for HPTh and HPTo. Thermal hyperalgesia was present in both groups of IBS patients relative to controls, with IBS patients reporting significantly lower pain threshold and pain tolerance at both test sites. Cluster analysis revealed the presence of subgroups of IBS patients based on thermal hyperalgesia. One cluster （17% of the sample） showed a profile of heat pain sensitivity very similar to that of healthy controls; a second cluster （47% of the sample） showed moderate heat pain sensitivity; and a third cluster （36% of the sample） showed a very high degree of thermal hyperalgesia.
CONCLUSION： A subset of IBS patients had thermal hypersensitivity compared to controls, who reported significantly lower HPTh and HPTo. All IBS patients had a higher score on the FBDSI than controls. Interestingly, the subset of IBS patients with high thermal sensitivity （36%） had the highest FBDSI score compared to the other two groups of IBS patients.