Glucagon-like peptide 1 (GLP-1) is an intestinal incretin hormone that regulates blood glucose levels and is produced by enteroendocrine cells.Intestinal Lactobacilli may affect its secretion.In this study, a simple co-culture system consisting of aerobic cells, mucous layer, and bacteria (microaerobic) was used to analyze the effect of three lactobacilli strains (L.rhamnosus, L.plantarum, and L.johnsonii) on GLP-1 secretion by enteroendocrine cells.The dose effect of the strains and the influence of oxygen and mucous layer on the co-culture system were also investigated.Results showed that L.rhamnosus at concentrations of 1×109, 1×108, and 1×107 CFU/1 000 mL could increase the secretion of GLP-1 by cells.Low concentrations of L.plantarum and L.johnsonii (< 1×107 CFU/1 000 mL) did not affect GLP-1 production, but at concentrations higher than 1×108 CFU/1 000 mL, they significantly decreased (P<0.05) the secretion.The mucous layer is an important barrier between intestinal cells and microbes.Its absence significantly reduced (P<0.05) the secretion of GLP-1 in the co-culture system.However, the effects of limited oxygen conditions on co-culture systems with different bacteria strains differed.When co-cultured with L.rhamnosus and L.plantarum, the limited oxygen conditions had no effect on GLP-1 secretion, but when co-cultured with L.johnsonii, it significantly decreased (P<0.05) the secretion.This study utilized a co-culture system with simple operation and low equipment requirements to mimic the in vivo environment.The significance of the mucus layer in this system was demonstrated.Moreover, it was confirmed that L.rhamnosus promotes the secretion of GLP-1 by enteroendocrine cells.The study also revealed that different strains of lactobacilli have distinct effects on GLP-1 and that there is a dose-effect relationship.The research provides a new method reference for explaining the interaction between probiotics and body cells and provides scientific evidence for the regulation of GLP-1 metabolism by lactobacilli.
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