Laboratory of Neuronal Network and Systems Biology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.
Hubei Key Laboratory of Cardiovascular, Cerebrovascular, and Metabolic Disorders, Hubei University of Science and Technology, Xianning, China.
Neurogastroenterol Motil. 2019 May;31(5):e13556. doi: 10.1111/nmo.13556. Epub 2019 Feb 10.
Intestinal barrier dysfunction is a key etiologic factor of irritable bowel syndrome (IBS). Metformin improves intestinal barrier function, although the underlying mechanism has yet to be fully explained. This study evaluates the protective effect of metformin on colonic barrier integrity and explores the underlying cellular mechanisms.
IBS-like rats were induced by maternal separation. Metformin was administered daily by gavage at 08:30, and rat pups were then separated from their mother. Visceral hyperalgesia and depression-like behaviors were evaluated by colorectal distension, sucrose preference tests, and forced swimming tests. Intestinal integrity was analyzed using sugar probes and transmission electron microscopy. Inflammatory factors and the levels of corticotropin-releasing factor were assessed by PCR and ELISA. The number of mast cells was evaluated by toluidine blue staining. Protein expression and localization were determined using Western blot and immunochemistry.
Metformin pretreatment (a) reduced visceral hypersensitivity to colorectal distension, immobility time and enhanced sucrose consumption; (b) decreased urine lactulose/mannitol ratio and sucralose output; (c) inhibited the dilation of tight junction and prevented claudin-4 translocation; (d) inhibited mast cell activation and downregulated the expression of IL-6, IL-18, tryptase, PAR-2, and ERK activation; (e) inhibited claudin-4 phosphorylation at serine sites and interactions between clau-4 and ZO-1.
CONCLUSIONS & INFERENCES: Metformin may block mast cell activation to reduce PAR-2 expression and subsequently inhibit ERK activation and clau-4 phosphorylation at serine sites to normalize the interaction of clau-4 and ZO-1 and clau-4 distribution. Metformin may be clinically beneficial for patients with IBS or IBS-like symptoms.
肠屏障功能障碍是肠易激综合征（IBS）的一个关键病因。二甲双胍可改善肠屏障功能，但具体机制尚未完全阐明。本研究评估了二甲双胍对结肠屏障完整性的保护作用，并探讨了其潜在的细胞机制。
通过母婴分离诱导 IBS 样大鼠。二甲双胍于 08:30 时经灌胃给药，然后将大鼠幼崽与其母亲分离。通过结肠扩张、蔗糖偏好试验和强迫游泳试验评估内脏痛觉过敏和抑郁样行为。使用糖探针和透射电子显微镜分析肠道完整性。通过 PCR 和 ELISA 评估炎性因子和促肾上腺皮质释放因子的水平。通过甲苯胺蓝染色评估肥大细胞数量。使用 Western blot 和免疫组织化学测定蛋白表达和定位。
二甲双胍预处理（a）降低了对结肠扩张的内脏高敏感性、不动时间和增加了蔗糖消耗；（b）降低了尿乳果糖/甘露醇比和蔗糖输出；（c）抑制了紧密连接的扩张并防止了 Claudin-4 易位；（d）抑制了肥大细胞激活并下调了 IL-6、IL-18、胰蛋白酶、PAR-2 和 ERK 激活的表达；（e）抑制 Claudin-4 丝氨酸位点磷酸化和 Claudin-4 与 ZO-1 的相互作用。
二甲双胍可能通过阻断肥大细胞激活来减少 PAR-2 的表达，从而抑制 ERK 激活和 Claudin-4 丝氨酸位点的磷酸化，以恢复 Claudin-4 和 ZO-1 的相互作用和 Claudin-4 的分布。二甲双胍可能对 IBS 或 IBS 样症状患者具有临床益处。
