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Objective: To explore the effect of herb-partitioned moxibustion (HPM) on tight junctions (TJs) of intestinal epithelial cells in Crohn disease (CD) mediated by tumor necrosis factor-α (TNF-α)-nuclear factor kappa B (NF-κB)-myosin-light- chain kinase (MLCK) pathway. Methods: Forty-eight male Sprague-Dawley rats were randomly divided into a normal control (NC) group, a model control (MC) group, an HPM group and a mesalazine (MESA) group, with 12 rats in each group. Trinitrobenzene sulfonic acid (TNBS) was administered to establish CD models. When the model was confirmed a success, the HPM group rats were treated with HPM at Tianshu (ST 25) and Qihai (CV 6), while the MESA group rats were given MESA solution by lavage. When the intervention finished, the colonic epithelial tissues were separated, purified and cultured in each group to establish the intestinal epithelial barrier model in vitro, and TNF-α was added (100 ng/mL) in the culture medium and maintained for 24 h to establish an increased epithelial permeability model. Transepithelial electrical resistance (TEER) was used to examine the permeability of the barrier; Western blot was used to observe the expressions of the proteins related to TJs of intestinal epithelial cells mediated by TNF-α-NF-κB-MLCK pathway; immunofluorescence staining was used to observe the expressions and distributions of tight junction proteins in the intestinal epithelium. Results: After TNF-α induction, compared with the MC+TNF-α group, the TEER value increased significantly in the HPM+TNF-α and MESA+TNF-α groups (both P<0.001); the expressions of nuclear factor kappa B (NF-κB) p65, MLCK, myosin light chain (MLC), tumor necrosis factor receptor-associated factor 6 (TRAF6) and receptor interaction protein-1 (RIP1) decreased significantly (P<0.01 or P<0.05), and the expression of zinc finger protein A20 (A20) increased significantly (P<0.01); the expressions of occludin, claudin-1, zonula occludens protein 1 (ZO-1) and F-actin also increased significantly (all P<0.01). Compared with the MESA+TNF-α group, the expressions of MLC, occludin, claudin-1, ZO-1 and F-actin increased significantly in the HPM+TNF-α group (P<0.01 or P<0.05). Conclusion: HPM can protect or repair the damage of intestinal epithelial barrier in CD rats, which may be achieved through modulating the abnormal TJs in intestinal epithelium mediated by TNF-α-NF-κB-MLCK pathway.
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Objective:To explore the possible mechanism of electroacupuncture to improve detrusor hyperreflex after suprasacral spinal cord injury. Methods:A total of 60 female Sprague-Dawley rats were included. According to the random number table, twelve were selected as the blank group, twelve as the sham operation group, and the remaining 36 were made neurogenic bladder models using modified T10 spinal cord transection. After that, twelve of them were randomly selected as the model group and twelve were as the electroacupuncture group from the model rats that met the requirements. On the 19th day after modelling, Ciliao (BL32), Zhongji (RN3) and Sanyinjiao (SP6) were taken for electroacupuncture. After seven days of continuous treatment, urodynamic testing was performed, content of cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) in detrusor was determined by ELISA, and the level of phosphorylation of myosin light chain kinase (p-MLCK) of detrusor was determined by Western blotting. Results:Compared with the blank group and the sham operation group, the maximum bladder capacity and bladder compliance significantly reduced (P < 0.01), and the base pressure and leakage point pressure of bladder significantly increased (P < 0.01); the content of cAMP and PKA in detrusor reduced (P < 0.01), p-MLCK in detrusor reduced (P < 0.05) in the model group. Compared with the model group, the maximum bladder capacity and bladder compliance increased (P < 0.01), the base pressure of the bladder and the pressure at the leak point decreased (P < 0.05); the contents of cAMP and PKA protein in detrusor increased (P < 0.05), the p-MLCK in detrusor increased (P < 0.05) in the electroacupuncture group. Conclusion:Electroacupuncture at Ciliao, Zhongji and Sanyinjiao points could improve the bladder function of rats with detrusor hyperreflex after complete spinal cord injury, and its mechanism may be related to up-regulating the expression of cAMP and PKA, phosphorylating and inactivating p-MLCK, which promote relaxation of detrusor.
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OBJECTIVE@#To observe the effect of acupoint thread-embedding on tight junction of intestinal mucosal epithelial barrier in rats with ulcerative colitis (UC) under the state of "deficiency and stasis", and to explore its mechanism.@*METHODS@#Sixty male SD rats were randomly divided into a control group (@*RESULTS@#Compared with the control group, in the model group the body weight was decreased (@*CONCLUSION@#The thread-embedding could repair the tight junction of intestinal mucosa epithelium and reduce the permeability of intestinal mucosa epithelium, which may be related to the decrease of the expression of CaMKⅡ, MLCK and other protein kinases.
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Animals , Male , Rats , Acupuncture Points , Colitis, Ulcerative/therapy , Epithelium , Intestinal Mucosa , Rats, Sprague-Dawley , Tight JunctionsABSTRACT
OBJECTIVE@#To investigate the effect of Chang'an II Decoction ( II ))-containing serum on intestinal epithelial barrier dysfunction in rats.@*METHODS@#Tumor necrosis factor (TNF)-α-induced injury of Caco-2 monolayers were established as an inflammatory model of human intestinal epithelium. Caco-2 monolayers were treated with blank serum and Chang'an II Decoction-containing serum that obtained from the rats which were treated with distilled water and Chang'an II Decoction intragastrically at doses of 0.49, 0.98, 1.96 g/(kg·d) for 1 week, respectively. After preparation of containing serum, cells were divided into the normal group, the model group, the Chang'an II-H, M, and L groups (treated with 30 ng/mL TNF-α and medium plus 10% high, middle-, and low-doses Chang'an II serum, respectively). Epithelial barrier function was assessed by transepithelial electrical resistance (TER) and permeability of fluorescein isothiocyanate (FITC)-labeled dextran. Transmission electron microscopy was used to observe the ultrastructure of tight junctions (TJs). Immunofluorescence of zonula occludens-1 (ZO-1), claudin-1 and nuclear transcription factor-kappa p65 (NF-κ Bp65) were measured to determine the protein distribution. The mRNA expression of myosin light chain kinase (MLCK) was measured by real-time polymerase chain reaction. The expression levels of MLCK, myosin light chain (MLC) and p-MLC were determined by Western blot.@*RESULTS@#Chang'an II Decoction-containing serum significantly attenuated the TER and paracellular permeability induced by TNF-α. It alleviated TNF-α-induced morphological alterations in TJ proteins. The increases in MLCK mRNA and MLCK, MLC and p-MLC protein expressions induced by TNF-α were significantly inhibited in the Chang'an II-H group. Additionally, Chang'an II Decoction significantly attenuated translocation of NF-κ Bp65 into the nucleus.@*CONCLUSION@#High-dose Chang'an II-containing serum attenuates TNF-α-induced intestinal barrier dysfunction. The underlying mechanism may be involved in inhibiting the MLCK-MLC phosphorylation signaling pathway mediated by NF-κ Bp65.
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Objective@#To investigate the regulation of hypoxia-inducible factor-1α (HIF-1α) on permeability of rat vascular endothelial cells and the mechanism.@*Methods@#Twelve male Sprague-Dawley rats aged 35 to 38 days were collected and vascular endothelial cells were separated and cultured. The morphology of cells was observed after 4 days of culture, and the following experiments were performed on the 2nd or 3rd passage of cells. (1) Rat vascular endothelial cells were collected and divided into blank control group, negative control group, HIF-1α interference sequence 1 group, HIF-1α interference sequence 2 group, and HIF-1α interference sequence 3 group according to the random number table (the same grouping method below), with 3 wells in each group. Cells in negative control group, HIF-1α interference sequence 1 group, HIF-1α interference sequence 2 group, and HIF-1α interference sequence 3 group were transfected with GV248 empty plasmid, recombinant plasmid respectively containing HIF-1α interference sequence 1, interference sequence 2, and interference sequence 3 with liposome 2000. Cells in blank control group were only transfected with liposome 2000. After transfection of 24 h, expression levels of HIF-1α mRNA and protein of cells in each group were respectively detected by reverse transcription real-time fluorescent quantitative polymerase chain reaction and Western blotting (the same detecting methods below) . The sequence with the highest interference efficiency was selected. (2) Another batch of rat vascular endothelial cells were collected and divided into blank control group, negative control group, and HIF-1α low expression group, with 3 wells in each group. Cells in blank control group were only transfected with liposome 2000, and cells in negative control group and HIF-1α low expression group were respectively transfected with GV248 empty plasmid and low expression HIF-1α recombinant plasmid selected in experiment (1) with liposome 2000. After 14 days of culture, the mRNA and protein expressions of HIF-1α in each group were detected. (3) Another batch of rat vascular endothelial cells were collected and divided into blank control group, negative control group, and HIF-1α high expression group, with 3 wells in each group. Cells in blank control group were transfected with liposome 2000, and cells in negative control group and HIF-1α high expression group were respectively transfected with GV230 empty plasmid and HIF-1α high expression recombinant plasmid with liposome 2000. After 14 days of culture, the mRNA and protein expressions of HIF-1α of cells in each group were detected. (4) After transfection of 24 h, cells of three groups in experiment (1) and three groups in experiment (2) were collected, and mRNA and protein expressions of myosin light chain kinase (MLCK), phosphorylated myosin light chain (p-MLC), and zonula occludens 1 (ZO-1) of cells were detected. Data were processed with one-way analysis of variance and t test.@*Results@#After 4 days of culture, the cells were spindle-shaped, and rat vascular endothelial cells were successfully cultured. (1) The interference efficiencies of HIF-1α of cells in HIF-1α interference sequence 1 group, HIF-1α interference sequence 2 group, and HIF-1α interference sequence 3 group were 47.66%, 45.79%, and 62.62%, respectively, and the interference sequence 3 group had the highest interference efficiency. After transfection of 24 h, the mRNA and protein expression levels of HIF-1α of cells in interference sequence 3 group were significantly lower than those in blank control group (t=18.404, 9.140, P<0.01) and negative control group (t=15.099, 7.096, P<0.01). (2) After cultured for 14 days, the mRNA and protein expression levels of HIF-1α of cells in HIF-1α low expression group were significantly lower than those in blank control group (t=21.140, 5.440, P<0.01) and negative control group (t= 14.310, 5.210, P<0.01). (3) After cultured for 14 days, the mRNA and protein expression levels of HIF-1α of cells in HIF-1α high expression group were significantly higher than those in blank control group (t=19.160, 7.710, P<0.01) and negative control group (t= 19.890, 7.500, P<0.01). (4) After transfection of 24 h, the mRNA expression levels of MLCK and p-MLC of cells in HIF-1α low expression group were significantly lower than those in blank control group (t=2.709, 4.011, P<0.05 or P<0.01) and negative control group (t=2.373, 3.744, P<0.05 or P<0.01). The mRNA expression level of ZO-1 of cells in HIF-1α low expression group was significantly higher than that in blank control group and negative control group (t=4.285, 5.050, P<0.01). The mRNA expression levels of MLCK and p-MLC of cells in HIF-1α high expression group were significantly higher than those in blank control group (t=9.118, 11.313, P<0.01) and negative control group (t=9.073, 11.280, P<0.01). The mRNA expression level of ZO-1 of cells in HIF-1α high expression group was significantly lower than that in blank control group and negative control group (t=2.889, 2.640, P<0.05). (5) After transfection of 24 h, the protein expression levels of MLCK and p-MLC of cells in HIF-1α low expression group were significantly lower than those in blank control group (t=2.652, 3.983, P<0.05 or P<0.01) and negative control group (t=2.792, 4.065, P<0.05 or P<0.01). The protein expression of ZO-1 of cells in HIF-1α low expression group was significantly higher than that in blank control group and negative control group (t=3.881, 3.570, P<0.01). The protein expression levels of MLCK and p-MLC of cells in HIF-1α high expression group were 1.18±0.24 and 0.68±0.22, which were significantly higher than 0.41±0.21 and 0.35±0.14 in blank control group (t=5.011, 3.982, P<0.05 or P<0.01) and 0.43±0.20 and 0.36±0.12 in negative control group (t= 4.880, 3.862, P<0.05 or P<0.01). The protein expression level of ZO-1 of cells in HIF-1α high expression group was 0.08±0.06, which was significantly lower than 0.20±0.09 in blank control group and 0.19±0.09 in negative control group (t=4.178, 3.830, P<0.05 or P<0.01).@*Conclusions@#HIF-1α up-regulates expressions of MLCK and p-MLC and down-regulates expression of ZO-1, thereby increasing the permeability of rat vascular endothelial cells.
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Aim To investigate the protective effect of paeoniflorin on TNF-α induced intestinal epithelial barrier dysfunction and its mechanisms.Methods The Caco-2 cells were cultured and the MTF assay was used to determine the effects of the paeoniflorin on Caco-2 cell activity.The Caco-2 cell intestinal epithelial barrier dysfunciton model was established through incubation of cells with TNF-α.The effects of paeoniflorin on intestinal epithelial barrier dysfunciton were studied.Results The transmembrane resistance in Caco-2 epithelial barrier was significantly reduced by TNF-α incubation;MLCK significantly increased,while tight junction protein occludin and ZO-1 significantly decreased by TNF-α.These changes were significantly reversed by paeoniflorin,which reduced MLCK expression and enhanced expression of occludin and ZO-1.The protective effects against epithelial barrier dysfunction could be abrogated by small interfering RNA(siRNA) of MLCK.Conclusions Paeoniflorin alleviates the epithelial barrier dysfunction induced by TNF-αthrough down-regulation of MLCK and enhancement of tight junction protein occludin and ZO-1.This study supplies a potential candidate drug for the clinical treatment of inflammatory bowel diseases.
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Objective To investigate the effects of curcumin on myosin light chain kinase(MLCK)in the intestinal mucosa of rats with nonalcoholic fatty liver disease(NAFLD). Methods 35 SD rats were randomly di-vided into the normal control group ,the high fat group and the curcumin group. The high fat group ,curcumin group were given high fat diet for 16 weeks. After 8 weeks of high fat feeding in the curcumin group ,the rats were gavaged with 200 mg/(kg·d)curcumin for 8 weeks. The levels of ALT,AST,LPS and DAO in blood and expres-sion of MLCK in the intestinal mucosa were detected. The changes of liver pathology and tight junction(TJ)of the intestinal mucosa were observed. Results Compared with the control group,the blood levels of ALT,AST,LPS and DAO in the high fat group were obviously increased(P<0.05);Compared with the high fat group,the blood levels of ALT、AST、LPS and DAO in the curcumin group were obviously decreased (P < 0.05). In the high fat group ,hepatocellular steatosis was obvious ,while in the curcumin group hepatocellular steatosis was decreased. TJ was disrupted in the high fat group ,and the intercellular space was larger in the TJ group than the control group (P<0.05). The intercellular space was narrower in the curcumin group than the high fat group(P<0.05). The expression of MLCK in the high fat group was significant higher than that in the control group(P<0.05). The pos-itive staining in the curcumin group was significant lower than that in the high fat group (P < 0.05). Conclusion Curcumin can ameliorate hepatic steatosis by downregulating expression of MLCK in the intestinal mucosa of rats with NAFLD,improving TJ structure of the intestinal mucosa.
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Objective To investigate the effects of curcumin on myosin light chain kinase(MLCK)in the intestinal mucosa of rats with nonalcoholic fatty liver disease(NAFLD). Methods 35 SD rats were randomly di-vided into the normal control group ,the high fat group and the curcumin group. The high fat group ,curcumin group were given high fat diet for 16 weeks. After 8 weeks of high fat feeding in the curcumin group ,the rats were gavaged with 200 mg/(kg·d)curcumin for 8 weeks. The levels of ALT,AST,LPS and DAO in blood and expres-sion of MLCK in the intestinal mucosa were detected. The changes of liver pathology and tight junction(TJ)of the intestinal mucosa were observed. Results Compared with the control group,the blood levels of ALT,AST,LPS and DAO in the high fat group were obviously increased(P<0.05);Compared with the high fat group,the blood levels of ALT、AST、LPS and DAO in the curcumin group were obviously decreased (P < 0.05). In the high fat group ,hepatocellular steatosis was obvious ,while in the curcumin group hepatocellular steatosis was decreased. TJ was disrupted in the high fat group ,and the intercellular space was larger in the TJ group than the control group (P<0.05). The intercellular space was narrower in the curcumin group than the high fat group(P<0.05). The expression of MLCK in the high fat group was significant higher than that in the control group(P<0.05). The pos-itive staining in the curcumin group was significant lower than that in the high fat group (P < 0.05). Conclusion Curcumin can ameliorate hepatic steatosis by downregulating expression of MLCK in the intestinal mucosa of rats with NAFLD,improving TJ structure of the intestinal mucosa.
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Ardipusilloside-I is a natural triterpenoid saponin, which was isolated from Ardisia pusilla A. DC. The aim of the study was to evaluate the stimulation of ardipusilloside-I on gastrointestinal motility in vitro and in vivo. The experiment of smooth muscle contraction directly monitored the contractions of the isolated jejunal segment (IJS) in different contractile states, and the effects of ardipusilloside-I on myosin were measured in the presence of Ca²⁺-calmodulin using the activities of 20 kDa myosin light chain (MLC₂₀) phosphorylation and myosin Mg²⁺-ATPase. The effects of ardipusilloside-I on gastro emptying and intestinal transit in constipation-predominant rats were observed, and the MLCK expression in jejuna of constipated rats was determined by western blot. The results showed that, ardipusilloside-I increased the contractility of IJS in a dose-dependent manner and reversed the low contractile state (LCS) of IJS induced by low Ca²⁺, adrenaline, and atropine respectively. There were synergistic effects on contractivity of IJS between ardipusilloside-I and ACh, high Ca²⁺, and histamine, respectively. Ardipusilloside-I could stimulate the phosphorylation of MLC₂₀ and Mg²⁺-ATPase activities of Ca²⁺- dependent phosphorylated myosin. Ardipusilloside-I also stimulated the gastric emptying and intestinal transit in normal and constipated rats in vivo, respectively, and increased the MLCK expression in the jejuna of constipation-predominant rats. Briefly, the findings demonstrated that ardipusilloside-I could effectively excite gastrointestinal motility in vitro and in vivo.
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Animals , Rats , Ardisia , Atropine , Blotting, Western , Epinephrine , Gastric Emptying , Gastrointestinal Motility , Histamine , In Vitro Techniques , Muscle, Smooth , Myosin Light Chains , Myosin-Light-Chain Kinase , Myosins , Phosphorylation , SaponinsABSTRACT
Objective To study the impact of tumor necrosis factor-α (TNF-α) and its antagonist on the expressions of intestinal mucosa claudin-1,Zonula Occludens-1 (ZO-1) and myosin light chain kinase (MLCK) in rat models of acute liver failure.Methods Fifty four healthy male SpragueDawley (SD) rats were randomly divided into normal control group,model group and intervention group according to a random number table.Rats in normal control (n=6) group were intraperitoneally injected with 0.9％ saline (12 mL/kg).Rats in model group (n=24) and intervention group (n=24) were intraperitoneally injected with a full dose of D-galactosamine (D-GalN) at a dose of 1 200 mg/kg to establish model of acute liver failure,while rats in intervention group were intraperitoneally injected with TNF-α antagonists (rhTNFR∶Fc) at a dose of 12.5 mg/kg before 24 hours given D-GalN.At each time point of hour 8,24,48 and 72,six rats in both model group and the intervention group were sacrificed,respectively,while the normal control group were all anesthetized and sacrificed at 72 h.Models were repeated five times.Serum liver function was detected by biochemical method,and serum TNF-α level was detected by enzyme-linked immunosorbent assay (ELISA).Hematoxylin-eosin (HE) stained sections of liver and terminal ileum were examined under an optical microscope for pathological changes;and protein expression of the terminal ileum Claudin-1,ZO-1 protein and MLCK were determined by immunohistochemistry and Western blot.Means among groups were compared with t test.Results Acute liver failure was successfully induced in the D-GalN injected rats.In the model group,alanine aminotransferase (ALT) began to decline,total bilirubin continued to rise,and enzyme-jaundice separation developed at hour 72.But total bilirubin in intervention group at hour 72 was decreased.Light microscope showed that at hour 72,villus lodged at terminal ileum in the model group with part of villus tip failing off in the model group.Villus mucosa and submucosa interstitial were edema and infiltrated with numerous neutrophils.The terminal ileum kept integrate in the intervention group,and villus mucosa and submucosa were mild edema and only infiltrated with a small amount of neutrophil.Expressions of tumor necrosis necrosis factor (TNF)-α in rats of model group and intervention group were gradually increased and peaked at hour 24 ([239.83 ± 15.81] and [182.71± 17.08] ng/L,respectively),which were significantly higher than that of the control group ([24.19±3.57] ng/L,t=22.68and 15.73,respectively;both P＜0.01).Expression of serumTNF-α in the intervention group was significantly lower than that of model group (t=4.58,P＜0.01).Expressions of Claudin-1 and ZO-1 in model group decreased gradually at an early stage and reached the lowest level at hour 24 (0.355 ± 0.068 and 0.387 ± 0.091,respectively),which were both significantly lower than that of control group (1.640±0.188 and 1.015±0.150,respectively;t=12.87 and 7.14,respectively;both P＜0.01).In the intervention group,expressions of Claudin-1 and ZO-1 also decreased to the lowest level at hour 24 (1.051 ± 0.370 and 0.642 ± 0.082,respectivley),which were both significantly lower than that of control group (t =2.84 and 4.36,respectively;both P＜0.05),but significantly higher than model group with stastically difference (t =3.70 and 4.15,respectively;both P＜0.01).MLCK protein levels in the model and intervention group were gradually increased,which peaked at hour 24 (1.298±0.194 and 1.033 ± 0.073,respectively),significantly higher than the control group (0.460±0.069,t=8.16 and 11.44,both P＜0.01);and MLCK in the intervention group was lower than that in the model group with statistically difference (t=2.56,P＜0.05).Conclusions Expression of serum TNF-α in rat model of acute liver failure increases,which leads to decreased expression of Claudin-1 and ZO-1,and increased expression of MLCK,makes cell shrunk and cell gap increased.TNF-α antagonist could significantly reduce the inflammation and liver cell apoptosis,improve liver function by inhibiting MLCK expression and preventing decrease of Claudin-1 and ZO-1 proteins.
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Aim To investigate whether Hcy influenced the intestinal mucosal permeability by regulating MEK-ERK-MLCK pathway. Methods SD rats were divided into 4 groups:normal group, normal+Hcy group, TN-BS/ethanol group, TNBS/ethanol+Hcy group. Experi-mental colitis model with hyperhomocystinemia was es-tablished in rats with intracolonic administration of TN-BS and subcutaneous injection of Hcy. The colonic mucosal tissue was collected for histopathological exam-ination and activity of myeloperoxidase ( MPO ) . The protein expression of MLCK, p-MLCK, MEK, ERK and p-ERK in intestinal mucosal tissues was examined by Western blot method. The mRNA expression of ML-CK was examined by RT-qPCR method. Result Com-pared with the normal group and TNBS group, the DAI and HI scores and the MPO activity were increased in TNBS/ethanol+Hcy group ( P <0. 01 ) . Western blot and RT-qPCR showed that expression of MLCK, p-ML-CK, MEK, ERK and p-ERK increased in small intes-tine in TNBS/ethanol+Hcy group. Conclusion Hcy can increase intestinal permeability in TNBS-induced colitis rats by regulating the expression of MEK-ERK-MLCK signal pathway.
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Objective To explore the impact and mechanism of miR-200 b on intestinal epithelial tight junction. Methods The negative-lentivirus and human-miR-200 b-lentivirus were employed to infect the Caco-2 cell thus establishing two stable cell lines which were then stimulated by 10 ng/mL human tumor necrosis factor-α(TNF-α) to establish the model of the intestinal epithelial injury. Those Caco-2 cells were divided into NC, NC+TNF-α, 200b, and 200b+TNF-αgroups.The tight junction permeability was detected by transepithelial electrical resistance (TEER) and Fluorescein isothiocyanate-labeled dextran (FITC-dextran). The protein alterations myosin light chain kinase (MLCK)/phosphorylated myosin light chain (P-MLC) pathways were measured by Western blot analysis. Results Compared to NC group, NC+TNF-αgroup had lower TEER, higher FITC-dextran, and up-regulated expressions of MLCK and P-MLC proteins (P
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OBJECTIVE: To study whether the effects of olanzapine on gastrointestinal motility is related to the serotonin antagonism and myosin light chain kinase. METHODS: Male Sprague-Dawley rats were randomly divided into four groups. Olanzapine gavage was performed for each treatment group during the course of 30 continuous days, while the same volume of saline was given to the rats in the control group. Defecation of the rats was observed on days 7 and 30 after olanzapine gavage. The effects of olanzapine on contraction of colonic smooth muscles were observed in ex vivo experiments. A Western blot was used to evaluate expression levels of the serotonin transporter (SERT) and MLCK in colon segments of the rats. RESULTS: ResultsaaCompared to the control group, 5-160 µM of olanzapine could inhibit dose-dependently the contraction of colonic smooth muscle ex vivo experiments. The maximum smooth muscle contraction effects of 5-HT and acetylcholine significantly decreased after treatment with 40-160 µM of olanzapine. Constipation was found in the olanzapine-treated rats on day 7 and have sustained day 30 after gavage. Expression of MLCK in olanzapine-treated rats was significantly decreased, whereas the expression of SERT significantly increased on the day 7, then significantly decreased on the day 30 after olanzapine gavage. CONCLUSION: SERT and MLCK may involve in the inhibition of colonic contraction induced by olanzapine.
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Animals , Humans , Male , Rats , Acetylcholine , Antipsychotic Agents , Blotting, Western , Colon , Constipation , Defecation , Gastrointestinal Motility , Muscle, Smooth , Myosin Light Chains , Myosin-Light-Chain Kinase , Myosins , Rats, Sprague-Dawley , Serotonin Plasma Membrane Transport Proteins , SerotoninABSTRACT
Myosin light chain kinase (MLCK) is a key enzyme involved in intestinal mucosal mechanical barrier and plays an important role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). This article describes the "two-hit theory" for NAFLD and gut-derived endotoxin which plays a major role in the pathogenesis of NAFLD, the relationship between endotoxin, MLCK, and NAFLD, and the impact of MLCK inhibitor ML-7 on the intestinal barrier. MLCK inhibitor ML-7 may hinder and delay the development and progression of NAFLD, providing a novel clinical idea for the early prevention of NAFLD.
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[ ABSTRACT] Myosin light chain kinase ( MLCK) activates the regulatory light chain of myosin II, and the phos-phorylated myosin light chain leads to actomyosin contractile activity, as well as the cell contraction and increasing intercel-lular gap, which finally results in endothelial barrier dysfunction.MLCK-dependent hyperpermeability occurs in response to multiple cell signaling molecules and signaling pathways, including Ca2+, Src, PKC, NO, cGMP and mitogen activated protein kinases ( MAPK) .In this review, different mechanisms of endothelial hyperpermeability mediated by MLCK are discussed.
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Objective To explore the expression and function of myosin light streptokinase (MLCK) in small intestine mucosa of acute necrotizing pancreatitis (ANP) rats.Methods Fifty-six male SD rats were randomly assigned to control group and ANP group.A rat model of ANP was reproduced by retrograde injection of 4％ sodium taurocholate into the biliopancreatic duct,while the control group underwent a sham operation.The rats were sacrificed at 6th,12th,24th,48th hour after ANP induction.Serum amylase、TNF α,IL 1β,diamine oxidase (DAO) were measured.The pathological scores in the pancreas and small intestine were observed.The ultrastructure and tight junction (TJ) changes in the small intestine mucosa were observed with an electron microscope.The localization and expression of MLCK in small intestine mucosa was determined by immunohistochemistry method.Results Compared to the control group,the serum amylase,TNF-α,IL-1 β,DAO level,in the ANP group were all significantly increased;[(4 978 ± 1 574) U/L vs (1 176 ± 124))U/L,(47.88 ± 15.85) μg/L vs (17.24 ± 1.99) μg/L,(132.48 ± 68.54) μg/L vs (23.51 ± 6.44) μg/L,(95.96 ± 30.84)μg/L vs (38.06 ± 17.73)U/L at 12 h],and the pathology scores of pancreas and small intestine were both significantly elevated [12 h:(12.2 ± 1.80) vs (4.68 ± 0.35),(2.58 ± 0.52) vs (0.58 ±0.26)] (P ＜0.05);the MLCK protein expression in small intestine mucosa was significantly increased in ANP group (12 h:0.1863 ± 0.0230 vs 0.1636 ± 0.0049),and the difference was statistically significant (P ＜0.05).The small intestine ultrastructure was seriously damaged and TJ was widened significantly in ANP Group.Conclusions The increased serum TNF alpha and IL-1β concentration and DAO activity and up-regulated MLCK protein expression in small intestine mucosa may damage the integrity of tight junction of intestinal epithelial cell and cause intestine mucosa barrier dysfunction.
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AIM: To investigate the effect of inhibiting myosin light chain kinase ( MLCK) on endothelin-1 (ET-1) induced proliferation and apoptosis of rat pulmonary artery smooth muscle cells (PASMCs).METHODS: Rat PASMCs were cultured and stimulated with ET-1.The cells were randomly divided into control group , ET-1 group and ET-1+MLCK inhibitor group (ET-1+M).Western blotting, MTT assay, [3H]-TdR incorporation and flow cytometry were employed to test the expression of myosin light chain (MLC) and MLCK, cell proliferation, cell cycle and apoptotic rate of PASMCs ,respectively .The phosphorylation of MLC was determined by glycerol-PAGE coupled with Western blotting .RE-SULTS:Compared with control group , the protein expression of MLCK and MLC phosphorylation significantly enhanced af -ter ET-1 stimulation.ET-1 markedly induced the proliferation and decreased the percentage of apoptotic rate in the PASMCs.However, pretreatment with ML-7, a MLCK inhibitor, significantly reversed the above effects induced by ET-1. CONCLUSION:MLCK inhibitor effectively inhibits the ET-1-induced proliferation and the cell cycle progression .
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Vascular hyporeactivity is an important factor in irreversible shock, and post-shock mesenteric lymph (PSML) blockade improves vascular reactivity after hemorrhagic shock. This study explored the possible involvement of myosin light chain kinase (MLCK) in PSML-mediated vascular hyporeactivity and calcium desensitization. Rats were divided into sham (n=12), shock (n=18), and shock+drainage (n=18) groups. A hemorrhagic shock model (40±2 mmHg, 3 h) was established in the shock and shock+drainage groups. PSML drainage was performed from 1 to 3 h from start of hypotension in shock+drainage rats. Levels of phospho-MLCK (p-MLCK) were determined in superior mesenteric artery (SMA) tissue, and the vascular reactivity to norepinephrine (NE) and sensitivity to Ca2+ were observed in SMA rings in an isolated organ perfusion system. p-MLCK was significantly decreased in the shock group compared with the sham group, but increased in the shock+drainage group compared with the shock group. Substance P (1 nM), an agonist of MLCK, significantly elevated the decreased contractile response of SMA rings to both NE and Ca2+ at various concentrations. Maximum contractility (Emax) in the shock group increased with NE (from 0.179±0.038 to 0.440±0.177 g/mg, P<0.05) and Ca2+ (from 0.515±0.043 to 0.646±0.096 g/mg, P<0.05). ML-7 (0.1 nM), an inhibitor of MLCK, reduced the increased vascular response to NE and Ca2+ at various concentrations in the shock+drainage group (from 0.744±0.187 to 0.570±0.143 g/mg in Emax for NE and from 0.729±0.037 to 0.645±0.056 g/mg in Emax for Ca2+, P<0.05). We conclude that MLCK is an important contributor to PSML drainage, enhancing vascular reactivity and calcium sensitivity in rats with hemorrhagic shock.
Subject(s)
Animals , Male , Calcium/metabolism , Lymph/physiology , Mesenteric Artery, Superior/physiopathology , Muscle, Smooth, Vascular/physiopathology , Myosin-Light-Chain Kinase/physiology , Shock, Hemorrhagic/physiopathology , Muscle Contraction , Mesenteric Artery, Superior/metabolism , Muscle, Smooth, Vascular/metabolism , Myosin Light Chains/metabolism , Myosin-Light-Chain Kinase/analysis , Random Allocation , Rats, Wistar , Shock, Hemorrhagic/enzymologyABSTRACT
Objective To investigate the effect and mechanism of anti-tumor necrosis factor (TNF)-α on the intestinal mucosal permeability in dextran sulfate sodium (DSS) induced colitis mice.Methods Eighteen C57BL/6J mice were evenly divided into healthy control group,model group and anti-TNF-α treated group.The mice of model group and anti-TNF-α treated group were fed with 5％DSS solution for 7 days.The mice of anti-TNF-α treated group were injected anti-TNF-α (5 mg/kg)intraperitoneally on the first and fourth day; control group and model group were substituted with equal volume saline injection.The mice were sacrificed at 7 days after modeling.The disease activity index (DAI) score was evaluated everyday.The intestinal permeability was examined by Evan′s blue (EB) method and FITC-dextran (FITC-D) method.The colon tissue was collected for observation under microscope and histological index (HI).The small intestinal tissues were examined under electron microscope.The 10％ homogenate of colon and intestinal mucosa was prepared,the activity of myeloperoxidase (MPO),the content of TNF-α and epithelial myosin light chain kinase (MLCK) concentration were determined with kits respectively.The expression of MLCK in intestinal mucosa was tested by Western blot assay.Single factor of variance between groups were analyzed.Results Compared with control group,the DAI of model group increased daily.Compared with model group,the DAI of anti-TNF-α treated group improved.In model group,mice intestinal epithelial cells junctional complex shortened and widened and the cell gap expanded.In anti-TNF-α treated group,the connection structure of mice intestinal epithelial cells was tighter.The activity of HI and MPO and the content of TNF-α of model group were higher than those of control group (P ＝ 0.008,0.006 and 0.001,respectively),all of those of anti-TNF-α treated group were lower than those of model group (P=0.004,0.008 and 0.005,respectively).The F value of three groups was 131.98,218.28 and 58.93,respectively.The contents of EB in mice intestinal wall and serum FITC-D of model group were higher than those of control group (P=0.003 and 0.010),and those of anti-TNF-α treated group were lower model group (P＝0.001 and 0.009).The F value of three groups was 69.36 and 17.96.The MLCK concentration in mice intestinal mucosa of model group [(71.10± 7.52) ng/g] was higher than that of control group [(18.56±9.92) ng/g,P＜0.01],that of anti-TNF-α treated group [(37.56±15.84) ng/g] was lower than model group (P=0.008),and the difference among these three groups was statistically significant (F＝ 17.23).The Western blot results indicated the expression of MLCK in intestinal mucosa of model group was higher than that of control group,and that of anti-TNF-α treated group was lower than model group.Conclusions Anti-TNF-α play an important role in improving colitis,and the intestinal mucosal permeability.The mechanism may be related with the regulation of MLCK expression.
ABSTRACT
Objective To evaluate the role of myosin light chain kinase(MLCK)in the increase in the permeability of human pulmonary microvascular endothelial cells(HPMVECs)induced by mechanical stretch.Methods HPMVECs were cultured in vitro and then randomly divided into 3 groups(n = 4 each): mechanical stretch group(group S),ML9 treatment group(group M)and control group(group C).In group S,the monolayer cells and magnetic beads coated with an RGD peptide were incubated in serum-free MCDB131 medium for 2 h,the unbound beads were washed out,and then the cells were exposed to magnetic twisting stimulation(MTS)for 2 h(frequency 3 Hz,intensity 4.2 mT).In group M,the monolayer cells and magnetic beads coated with an RGD peptide were incubated for 2 h in serum-free MCDB131 medium in which MLCK inhibitor ML9(50μmol/L)was added,and the other procedures were the same as in group S.In group C,the cells after washing as in group S were incubated for 2 h without exposing to MTS.Monolayer permeability was detected with FITC-dextran flux in transwell model.The distribution of integrin αVβ3 and actin was detected using the immunofluorescence assay.Results Compared with group C,the permeability of HPMVECs was significantly increased in group S,while no significant change was found in group M.Compared with group S,the permeability of HPMVECs was significantly decreased in group M.In addition,actin polymerized to form stress fiber,and integrin αVβ3 clustered at the end of stress fiber in group S,while actin mainly distributed in the surrounding area of the cell membrane and integrin αVβ3 evenly distributed on the cell surface in group C and M.Conclusion The mechanism by which mechanical stretch induces the increase in the permeability of HPMVECs is related to MLCK activation-mediated stress fiber formation and integrin αVβ3 clustering.