The Role And Mechanism Of Toll-like Receptor 4 In Diabetic Gastric Hypersensitivity

Background:Gastrointestinal dysfunction is a commom chronic complication of diabetes mellitus(DM),one of the most frequently complained GI symptoms is abdominal pain or discomfort in DM patients.The etiology of the gastrointestinal complications of DM remain eclusive.The aim of this study is to investigate the role and mechanism of toll-like 4(TLR4)in gastric hypersensitivity of diabetic rat.Methods:1.Diabetic model was induced by a single intraperitoneal injection of streptozotocin(STZ;65mg/kg)in adult female SD rats.2.Behavioral response to graded gastric balloon distention(GD)was used to examine normal and diabetic rats,and visceral motor responses to GD were calculated by electromyographic(EMG)recordings.3.Grastic-specific DRG neurons were labeled with DiI and acutely dissociated for measuring exctability under whole-cell patch clamp configurations.4.Western blot analysis was employed to measure the expression of TLR4,NF-κB and TRAF6 in gastric-specific DRGs.Results:1.Compared with the control group,diabetic rats were more sensitive to graded gastic balloon distention.2.The expression of TLR4 in diabetic gastric specific DRGs was greatly enhanced.Intrathecal administration of TLR4 inhibitor,CLI-095,could attenuate diabetic gastric hyperalgesia and reversed hypersensitivity of gastric-specific DRG neurons.3.The expression of NF-κB from gastric specific DRGs in diabetic rats was greatly enhanced.Intrathecal injection with NF-κB siRNA lentiviral vector(p65 siRNA),it remarkably attenuated gastric hypersensitivity and suppressed neuronal excitability in diabetic rats.4.Furthermore,TRAF6 expression of gastric DRGs in diabetic rats was greatly enhanced.CLI-095 treatment could reversed the upregulation of p65 and TRAF6 in diabetic gastric specific DRGs.Conclusion:Our results suggest that expression of TLR4 increased in T7–10DRGs after STZ injection,which induced activation of NF-κB by myeloid differentiation factor 88(MyD88)dependent signaling pathway,thus ultimately contributing to gastric hypersensitivity.The present and future research would reveal the molecular mechanism of diabetic chronic visceral hypersentivity,and provides a potential target for clinical treatment of diabetic visceral pain.