| Objects: Irritable bowel syndrome(IBS) is a frequent disorder of the lower gastrointestinal tract with characteristic abdominal pain or discomfort accompanied by altered bowel habits, including alterations in stool frequency and/or form or appearance, especially disordered defecation, which is one of the most common Functional Gastrointestinal Disorders. The population incidence rate is very high and it seriously affectes the quality of life and physical and mental health of patients because of recurrent disease. Serotonin transporter(SERT) is a universally existing cross-membrane transport protein that plays a key role in 5-hydroxytryptamine(5-HT)reuptake, thereby terminating the role of 5-HT in effect site, which is located in the enterochromaffin(EC) cells of the bowel and presynaptic membrane. SERT plays an important role in the pathogenesis of IBS. SERT gene polymorphism could influence the promoter efficiency, SERT mRNA and protein expression and therefore plays a key role in the development of IBS subtye. However, in addition to the gene itself, the intestinal microenvironment altering may also have an effect on the expression of the SERT. In clinical, treating IBS with diarrhea(D-IBS) and post-infection IBS(PI-IBS)patients using probiotics have achieved significant effects. LGG is one of Lactobacillus, which is researched most frequently in clinical. In the present study,we treated HT-29 cells,Caco-2cells and C57 BL / 6 mice with different concentration of LGG-s, then dectected the SERT mRNA and SERT protein in HT-29 cells,Caco-2cells and mice intestine by RT-PCR and westernblot.The aim is to investigate whether Lactobacillus rhamnosus supernatant will affect SERT expression, providing a new perspective on mechanism of probiotics theraping IBS.Methods:(1) HT-29 cells and Caco-2cells were treated with three different concentrations of LGG-s(ATCC53103) and LGG-s(CGMCC1.3724) for 12 h and 24 h.(2)We used four groups of mice [one group designated as the control group(n=12)and another three as the experimental groups; total =48 mice]. The mice of control group were free to water, the mice of another three groups were given double, three dilution and undiluted LGG-s in replace of tap water. Mice were given LGG-s for a total of 1week, 2weeks, 3weeks and 4 weeks during the experiment, respectively. 3mice of each group were killed and then removed the colons for later use every week, we detected SERT mRNA and SERT protein levels using RT-PCR and western-blot. Statistical analysis was carried out using SPSS 21.0 for Windows(SPSS,Chicago, IL, USA). One-way analysis of variance(ANOVA) and a post hoc(Dunnett’s T3 and Dunnett’sC) were used. For all analyses, a P-value of 0.05 was defined statistical significance.Results: The SERT mRNA and SERT protein in HT-29 cells and Caco-2cells were higher than control when treated with LGG-s(ATCC53103) for24h(p<0.05). In the animal study, the undiluted LGG-s(ATCC53103) can up-regulate SERT mRNA level for 9.4 folds in the first week(P=0.000, P < 0.05) and dropped rapidly in the second week. The double diluted LGG-s(ATCC53103)up-regulate SERT mRNA for2.07 folds at the first week, which slowly dropped to 1.75 folds within the second week and dropped under the base expression level at the third week(P=0.000,P=0.006, P=0.008).While, it climbed to 1.56 folds in the fourth week(P=0.007). The triple dilution LGG-s(ATCC53103) can’t up-regulate SERT mRNA expression until the end of the fourth week(P=0.004,P < 0.05). The SERT protein levels of double diluted LGG-s(ATCC53103) group were higher than that of control, but fluctuated with time. The SERT protein levels of the triple dilution LGG-s(ATCC53103) were higher than that of control in the last two weeks and increased with time.Conclusions:(1) LGG-s(ATCC53103)can increase SERT mRNA and SERT protein in intestinal epithelium and mice intestinal tissues;(2) It is time dependent that LGG-s(ATCC53103) upregulate SERT expression. |
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