BACKGROUND Impaired hypoglycaemic counterregulation has emerged as a critical concern for diabetic patients who may be hesitant to medically lower their blood glucose levels due to the fear of potential hypoglycaemic ...BACKGROUND Impaired hypoglycaemic counterregulation has emerged as a critical concern for diabetic patients who may be hesitant to medically lower their blood glucose levels due to the fear of potential hypoglycaemic reactions.However,the pathogenesis of hypoglycaemic counterregulation is still unclear.Glucagon-like peptide-1(GLP-1)and its analogues have been used as adjunctive therapies for type 1 diabetes mellitus(T1DM).The role of GLP-1 in counterregulatory dysfunction during hypoglycaemia in patients with T1DM has not been reported.AIM To explore the impact of intestinal GLP-1 on impaired hypoglycaemic counterregulation in type 1 diabetic mice.METHODS T1DM was induced in C57BL/6J mice using streptozotocin,followed by intraperitoneal insulin injections to create T1DM models with either a single episode of hypoglycaemia or recurrent episodes of hypoglycaemia(DH5).Immunofluorescence,Western blot,and enzyme-linked immunosorbent assay were employed to evaluate the influence of intestinal GLP-1 on the sympathetic-adrenal reflex and glucagon(GCG)secretion.The GLP-1 receptor agonist GLP-1(7-36)or the antagonist exendin(9-39)were infused into the terminal ileum or injected intraperitoneally to further investigate the role of intestinal GLP-1 in hypoglycaemic counterregulation in the model mice.RESULTS The expression levels of intestinal GLP-1 and its receptor(GLP-1R)were significantly increased in DH5 mice.Consecutive instances of excess of intestinal GLP-1 weakens the sympathetic-adrenal reflex,leading to dysfunction of adrenal counterregulation during hypoglycaemia.DH5 mice showed increased pancreaticδ-cell mass,cAMP levels inδcells,and plasma somatostatin concentrations,while cAMP levels in pancreaticαcells and plasma GCG levels decreased.Furthermore,GLP-1R expression in islet cells and plasma active GLP-1 levels were significantly increased in the DH5 group.Further experiments involving terminal ileal infusion and intraperitoneal injection in the model mice demonstrated that intestinal GLP-1 during recurrent hypoglycaemia hindered the secretion of the counterregulatory hormone GCG via the endocrine pathway.CONCLUSION Excessive intestinal GLP-1 is strongly associated with impaired counterregulatory responses to hypoglycaemia,leading to reduced appetite and compromised secretion of adrenaline,noradrenaline,and GCG during hypoglycaemia.展开更多
基金Supported by National Natural Science Foundation of China,No.81471048.
文摘BACKGROUND Impaired hypoglycaemic counterregulation has emerged as a critical concern for diabetic patients who may be hesitant to medically lower their blood glucose levels due to the fear of potential hypoglycaemic reactions.However,the pathogenesis of hypoglycaemic counterregulation is still unclear.Glucagon-like peptide-1(GLP-1)and its analogues have been used as adjunctive therapies for type 1 diabetes mellitus(T1DM).The role of GLP-1 in counterregulatory dysfunction during hypoglycaemia in patients with T1DM has not been reported.AIM To explore the impact of intestinal GLP-1 on impaired hypoglycaemic counterregulation in type 1 diabetic mice.METHODS T1DM was induced in C57BL/6J mice using streptozotocin,followed by intraperitoneal insulin injections to create T1DM models with either a single episode of hypoglycaemia or recurrent episodes of hypoglycaemia(DH5).Immunofluorescence,Western blot,and enzyme-linked immunosorbent assay were employed to evaluate the influence of intestinal GLP-1 on the sympathetic-adrenal reflex and glucagon(GCG)secretion.The GLP-1 receptor agonist GLP-1(7-36)or the antagonist exendin(9-39)were infused into the terminal ileum or injected intraperitoneally to further investigate the role of intestinal GLP-1 in hypoglycaemic counterregulation in the model mice.RESULTS The expression levels of intestinal GLP-1 and its receptor(GLP-1R)were significantly increased in DH5 mice.Consecutive instances of excess of intestinal GLP-1 weakens the sympathetic-adrenal reflex,leading to dysfunction of adrenal counterregulation during hypoglycaemia.DH5 mice showed increased pancreaticδ-cell mass,cAMP levels inδcells,and plasma somatostatin concentrations,while cAMP levels in pancreaticαcells and plasma GCG levels decreased.Furthermore,GLP-1R expression in islet cells and plasma active GLP-1 levels were significantly increased in the DH5 group.Further experiments involving terminal ileal infusion and intraperitoneal injection in the model mice demonstrated that intestinal GLP-1 during recurrent hypoglycaemia hindered the secretion of the counterregulatory hormone GCG via the endocrine pathway.CONCLUSION Excessive intestinal GLP-1 is strongly associated with impaired counterregulatory responses to hypoglycaemia,leading to reduced appetite and compromised secretion of adrenaline,noradrenaline,and GCG during hypoglycaemia.
