Muscarinic receptor subtypes and gastrointestinal smooth muscle function

The muscarinic receptor family expressed in smooth muscle throughout the body is thought to be composed of five subtypes coupling to distinct signaling systems, respectively. The population in smooth muscle is composed of mainly M₂ and M₃ subtypes in a 80% to 20% mixture. The muscarinic receptor, mainly M₃ receptor, play an important role in regulating gastrointestinal smooth muscle contraction. Selective muscarinic M3 antagonist should have therapeutic utility in the treatment of gastrointestinal disease.     

Advances in pathophysiology of gut microbiota

Before the technique of advanced high-throughput sequencing comes up, less is known about the human gut microbiota. It has been understood that trillions of microbes, in which 99% are bacteria, inhabit the human gut, forming a complicated ecological community. The gut microbiota has a great impact on human physiology and susceptibility to disease through its integrative metabolic activities and interactions with the host. In physiology, gut microbiota contributes to the host acquisition of nutrition and energy from diets, promoting development and maturation of gastrointestinal tract and immune system, and protecting host from invasion of enteropathogens. In pathology, dysbiosis underlying altered gut microbiota is associated with the susceptibilities to various diseases, including inflammatory bowel disease, type 1 diabetes, asthma, obesity, metabolic syndrome, autism and cancer. Understanding of the factors that underlie alterations in the composition and function of gut microbiota will be helpful in the development of drugs and the design of therapies that target it. This goal is formidable. It is because that the compositions of gut microbiota are immensely diverse, varying between individuals in a population and fluctuating over time in an individual, especially during early development and diseases. Viewing the gut microbiota with an ecological perspective will provide new insights into how to improve our health by targeting this microbial community in clinical treatments.     

Role of cyclooxygenase-2 in injury induced by hypoxia/reoxygenation in cultured rat cortical neurons

AIM: To observe the role of cyclooxygenase-2 (COX-2) in injury induced by hypoxia and reoxygenation in cultured rat cortical neurons and protective effects of COX-2 specific inhibitor NS398.METHODS: Primary rat cortical neuronal cells were cultured. Experiments were divided into control group, hypoxia/reoxygenation group and hypoxia/reoxygenation with COX-2 inhibitor group. Cell viability was measured by MTT assay. COX-2 protein expression was examined by Western blotting. Apoptosis was measured by DNA agarose electrophoresis.RESULTS: The expression levels of COX-2 increased significantly after neurons were treated with hypoxia and reoxygenation, compared with control group and hypoxia/reoxygenation with COX-2 inhibitor group (P＜0.05). COX-2 specific inhibitor NS398 protected neurons from death (P＜0.05 and P＜0.01), DNA fragmentation analysis showed DNA fragmentation was inhibited significantly by NS398.CONCLUSION: COX-2 is involved in the pathogenesis of neuron apoptosis induced by hypoxia/reoxygenation. COX-2 specific inhibitor significantly protects cortical neurons against hypoxia/reoxygenation injury and inhibits apoptosis induced by hypoxia.     

Effect of IL-10 on IL-1β-induced cyclooxygenase-2 expression and prostaglandin E2 release in human mesangial cells

AIM: To investigate the effect of IL-10 on IL-1β-induced prostaglandin E₂(PGE₂) release and cyclooxygenase-2(COX-2) expression in human mesangial cells and to examine whether IL-10 has effect on the biological function of IL-1β.METHODS: The PGE₂ concentration in supernatants of HMC was measured by radioimmunoassay. The COX-2 mRNA and protein were measured by RT-PCR and Western blot, respectively. RESULTS: PGE₂ and COX-2 were significantly increased after treatment with IL-1β(P＜0.01 for both) in cultured human mesangial cells. IL-10 had no effects on basical production of COX-2 and PGE₂(P＞0.05, respectively), while it inhibited IL-1β-elicited PGE₂ production, as well as COX-2 mRNA and protein expression in a concentration-dependent fashion. CONCLUSIONS: These results indicated that IL-10 depressed the IL-1β-induced release of PGE₂ and expression of COX-2. These data suggested that IL-10 could exert anti-inflammatory actions at several levels, not only by inhibiting the production of pro-inflammatory cytokines but also by suppressing their biological function.     

Effects of NS-398 on the proliferation and apoptosis of HepG2 cells

AIM: To evaluate the effects of NS-398, a cyclooxygenase-2(COX-2) inhibitor, on the proliferation and apoptosis in HepG2 cells. METHODS: The effects of NS-398 on the proliferation of HepG2 cells was evaluated by MTT. DNA fragmentation gel analysis was used to analyze the apoptotic cells; DNA ploidy and apoptotic cell percentage were examined by flow cytometry. Furthermore, the expression of COX-2 and Bcl-2 mRNA was identified by competitive RT-PCR. RESULTS: NS-398 inhibited cell proliferation and induced apoptosis in HepG2 in a concentration-dependent manner. DNA ploidy analysis showed that S phase cells were significantly decreased with NS-398 concentration increasing. The quiescent G₀/G₁ phase was accumulated with decreasing of Bcl-2 mRNA. Whereas NS-398 had no effect on the expression of COX-2 mRNA, no correlations were found between COX-2 mRNA and the HepG2 cell proliferation and apoptosis induced by NS-398 (r=0.056 and r=0.119, respectively). CONCLUSION: NS-398 significantly inhibits the proliferation and induces apoptosis in HepG2. Mechanisms may be involved in accumulation of quiescent G₀/G₁ phase and decrease in Bcl-2 mRNA expression, but independent to COX-2 mRNA expression.     

Expression of cyclooxygenase-2 in IL-1β-stimulated mesangial cells is medicated by NF-κB/IκB signal pathway

AIM: To investigate the role of NF-κB/IκB signal pathway in the regulation of cyclooxygenase-2 (COX-2) expression in human mesangial cells (HMC). METHODS: The PGE₂ concentration in supernatants of HMC was measured by radioimmunoassay. COX-2 mRNA and protein expression were determined by RT-PCR and Western blot. Electrophoretic mobility shift assay (EMSA) and Western blot were used to detect the activity of NF-κB and degradation of IκB. RESULTS: IL-1β significantly upregulated COX-2 expression and PGE₂ production in HMC. Significant up-regulation of NF-κB activation, nuclear translocation of p65 subunit, and degradation of IκB α and IκB β were observed in IL-1β-induced HMC. CONCLUSION: Expression of COX-2 in IL-1β-induced HMC is mediated by NF-κB/IκB signal pathway.     

Effects of cyclooxygenase-2 inhibitors on gastric epithelial cell proliferating and gastric healing following hydrochloric acid-induced injury in rats

AIM: To clarify the effects of specific and non-specific cyclooxygenase-2 (COX-2) inhibitors on gastric epithelial cell proliferating and gastric healing following acid-induced damage. METHODS: Male Sprague-Dawley rats were given 1 mL of 0.6 mol/L hydrochloric acid (HCl) into the stomach. Ten minutes after the administration of the acid, the animals were given NS-398 (COX-2 inhibitor) or indomethacin. Levels of COX-1 and COX-2 in the gastric mucosa before and after HCl-administration were analyzed using western blotting and immunohistochemical staining. Proliferating cell nuclear antigen (PCNA) was detected using immunohistochemistry for epithelial cell proliferation. Gastric lesion index (LI) was assessed using planimetry. RESULTS: Expression of COX-2 was enhanced mainly in surface epithelial cells and neck cells following HCl-administration. At 24 h following acid administration, PCNA labeling index (PCNA-LI) was (22.72±4.33) % and (21.98±5.18) % in the groups treated with 40 mg/kg of NS-398 and indomethacin respectively, which was significantly lower than that in the control group [ (34.46±3.61) %, P< 0.05 ]; LI was (1.28±0.58) % and (1.16±0.56) % in the groups treated with 4 mg/kg and 40 mg/kg of NS-398, respectively, which was significantly higher than that in the control group [ (0.58±0.24) %, P< 0.05 ]. CONCLUSIONS: The present study demonstrated that cyclooxygenase-2 inhibitors delayed gastric mucosal healing by suppressing expansion of the mucosal proliferative zone. These results provide evidence that cyclooxygenase-2 plays an important role in gastric mucosal regeneration.     

Advance in function of Eph-ephrin bidirectional signaling

Erythropoietin-producing hepatocyte (Eph) receptor, a membrane-bound protein tyrosine kinase receptor, plays the function of bidirectional signal transduction by binding to the membrane-tethered ephrin ligands on the neighboring cells. New findings reveal that Eph-ephrin bidirectional transduction of signals plays roles in embryonic deve-lopment and the physiological metabolism of adult organs, and its dysfunction is involved in a variety of pathological processes, such as cell adhesion and separation, angiogenesis, nerve growth and remodeling, bone remodeling, tumorigenesis and development, immune and metabolic diseases. Therefore, in-depth study of Eph-ephrin is of great significance for understanding the pathophysiological mechanisms and treatment of diseases. This review discusses the progress in Eph-ephrin bidirectional signal transduction system.     

Association among COX2, iNOS and p38MAPK in late phase of preconditioning in rat cardiomyocytes

AIM:To explore the association among COX₂ , iNOS and p38MAPK in late phase of preconditioning. METHODS: The expression of COX₂ , iNOS and p38MAPK activity were determined by western blotting and the injury of cardiomyocyte was assessed by LDH release and trypan blue exclusion in four groups: control group, group IPC (ischemic preconditioning), group SMT (iNOS inhibitor), group NS₃₉₈ (COX₂ inhibitor) and group SB (p38MAPK inhibitor).RESULTS:The expression of COX₂ in group IPC increased markedly in comparision with group SMT and group SB.The expression of iNOS in group SB was lower than that in group IPC and group NS₃₉₈.The difference of the amount of iNOS was not significant between group IPC and group NS₃₉₈.The difference of the amount of phospho-p38MAPK was not significant among group IPC, group SMT and group NS₃₉₈(P>0.05).The LDH was lower, and cell viability was higher in group IPC than those in control group.The LDH was higher, and cell viability was lower in group SMT, group NS₃₉₈ and group SB than those in group IPC. CONCLUSIONS:In late phase of preconditioning , the p38MAPK activity and expression of iNOS and COX₂ increase significantly in rat cardiomyocytes, activited p38MAPK mediates iNOS, then promotes COX₂ expression.     

Clinical pathophysiology of diabetic microangiopathy

In present review, the history of microangiopathy discovery and it’s modern concept were introduced and the pathophysiological changes of some vital organs in diabetes were analyzed. The roles of oxidation stress, distur bances of microvascular functions, microvascular endothelial cell damage, PKC and PPARγ in pathogenesis of diabetic microangiopathy were also discussed.     

The application of DWI and ADC mapping in acute cerebral infarction and basis of pathophysiology

AIM:To study the roles of isotropic diffusion weighted imaging(DWI)and apparent diffusion coeficient(ADC)mapping in diagnosing early cerebral infarction.METHODS:21 patients with cerebral in farction (8hyperacute,13 acute)were imaged with both convent ional MRI and single-shot echo-planar isotropic diffusion weighted imaging.Among them 12 pat ients had CT scanning simultaneously within 24 hours after onset.The positive rate of early in farction was comparted on CT,T₂WI and DEI.The change of the infarct lesion in DWI and T₂WI was also analysed.The av erage ADC,relat ive ADC(rADC)and the ADC from center to periphery of the lesion were calculated.RESULTS:8 hypera cute cerebral ischemic regions were revealed at DWI and ADC mapping,but CT and conventional MR were not.Hyperacute and acute infarcts appeared as areas of hyperintensity on DWI,and their average ADC was significantly depressed comparted with homologous contralateral tissue(0.698±0.104)×10^-3mm²/s vs(0.990±0.161)×10^-3mm²/s(P<0.01).ADC value in 21 hypera cute had gradient sign.CONCLUSION:Isotropic diffusion weighted imaging and ADC mapping have greater senstitivity for acute and hyperacute cerebral infarction than conventional MRI and CT,and may be used to defined the core and penumbra of ischemic lesion.     

干酪菌发酵液的毒性及促肠动力作用分析

对干酪菌发酵液进行了毒理学及其对动物肠动力的作用方面的研究，急性，恶毒实验表明，该产物对机体无毒性作用，在促肠动力实验中，45mg/mL发酵液对小肠有明显促进作用。     

Studies on the role of ET-1 and CGRP in the pathophysiology of ankylosing spondylitis and rheumatoid arthritis

AIM: To clarify the role of endothelin-1 (ET-1) and calcitonin gene related peptide(CGRP) in the pathophysiology of ankylosing spondylitis and rheumatoid arthritis. METHOD: Plasma/synovial fluid ET-1 and CGRP were measured by radioimmunoassay in patients with ankylosing spondylitis (AS) or rheumatoid arthritis (RA) and healthy control. RESULTS: ET-1 level in plasma of patients with AS and RA were significantly higher than that of healthy controls (P<0.01). No difference was found in plasma CGRP level between AS or RA and healthy control (P>0.05). CGRP level in synovial fluid was significantly higher than that in plasma (P<0.01), but ET-1 level was significantly lower than in plasma (P<0.01). CONCLUSION: These results suggest that ET-1 and CGRP play a pathogenic role in AS and RA.     

Effect of aerobic exercise on myenteric plexus and colonic dysfunction in type 2 diabetic rats

AIM: To observe the effect of aerobic exercise and dietary patterns on the colonic function of type 2 diabetic rats and the enteric nervous mechanism.METHODS: The rat model of type 2 diabetes was induced by high-fat diet (HFD) and streptozotocin (30 mg/kg, ip) injection, and the rats were divided into diabetes control (DC) group, HFD group, exercise (E) group and exercise combined with high fat diet (E+HFD) group. Some other healthy rats were arranged into normal control (NC) group. The rats in E group and E+HFD group received 8-week swimming training (5 d/week, 60 min/d). The colon samples were collected at the end of the 8th week for observation of the pathological changes by HE staining and for detection of colonic tension and expression of protein gene product 9.5(PGP9.5), substance P(SP) and vasoactive intestinal peptide (VIP).RESULTS: Diabetes induced significant myenteric plexus damages and marked reduction of neurons, while exercise protected the enteric nervous system from injuries. The expression of SP significantly increased in the rats with long-term aerobic exercise combined with a reasonable diet. However, high-fat diet combined with exercise did not obviously up-regulate SP. The positive expression of VIP in the colon significantly increased in both E group and E+HFD group. Aerobic exercise attenuated the atrophy and increased the tension in colonic smooth muscles.CONCLUSION: Diabetes induces muscular atrophy and tension attenuation in colonic smooth muscle, which can be reversed in some extent by aerobic exercise through the remolding of enteric nervous system.     

Research progress on pacemaker function of interstitial cells of Cajal in gastrointestinal tract

Interstitial cells of Cajal (ICC) is the pacemaker in the gastrointestinal tract, which is closely associated with the formation of slow wave and the regulation of gastrointestinal motility. As the pacemaker of gastrointestinal tract, the activation of pacing signal is triggered by the local calcium oscillation in the ICC. The change of calcium concentration can activate many relevant ion channels, such as NSCC, ANO1, VGCC, HCN channels and potassium channels, which can generate a large number of pacing current to form the slow wave and then propagated by the gap junction between the ICC networks and smooth muscle cells to make the peristalsis of gastrointestinal tract in autonomic rhythm. However, the mechanism of these ion channels in the pacemaker activity is still unclear, so we refer to make a review about the research progress on these pacemaker channels in this article to illuminate the mechanism of pacemaker activity in ICC.     

Effect of anesthesia depth with Narcotrend monitoring on cognitive function after gastrointestinal tumor surgery in elderly patients

AIM: To determine the correlation of anesthesia depth and the regional cerebral oxygen saturation (rSO₂) under the monitoring of Narcotrend (NT), and its predictive value for post-operative cognitive dysfunction (POCD) in senior patients undergoing gastrointestinal tumor surgery. METHODS: From June 2018 to June 2019, 90 elderly patients who were scheduled for gastrointestinal tumor surgery were enrolled. The depth of anesthesia was monitored with Narcotrend index (NTI), and the rSO₂ was evaluated by the near-infrared spectroscopy throughout the intraoperative periods. Cognitive function of the patients was evaluated by using mini-mental state examination (MMSE) 24 h after surgery. RESULTS: The patients (n=25) were diagnosed with POCD at 24 h after surgery. The patients with POCD had significantly longer duration of NTI<35 than that in non-POCD patients (P<0.05). Moreover, there was significantly longer duration of ΔrSO₂>13% to baseline and rSO₂<55%. The duration of NTI<35 was highly correlated with the duration of ΔrSO₂>13% to baseline (r=0.62, 95% CI=0.35~0.89, P=0.004). The serum S100β level in POCD group was significantly higher than that in non-POCD patients, while there was no statistically difference with respect to the serum level of interleukin-6 (IL-6). CONCLUSION: Deep anesthesia was likely to exacerbate the imbalance of cerebral oxygen supply and consumption in elderly surgical patients, which might further cause the injury of central nervous system. Narcotrend-guided anesthesia might have beneficial effects on the prevention of POCD especially in elderly patients.