Sensitive smell discrimination is based on structural plasticity of the olfactory bulb,which depends on migration and integration of newborn neurons from the subventricular zone.In this study,we examined the relations...Sensitive smell discrimination is based on structural plasticity of the olfactory bulb,which depends on migration and integration of newborn neurons from the subventricular zone.In this study,we examined the relationship between neural stem cell status in the subventricular zone and olfactory function in rats with diabetes mellitus.Streptozotocin was injected through the femoral vein to induce type 1 diabetes mellitus in Sprague-Dawley rats.Two months after injection,olfactory sensitivity was decreased in diabetic rats.Meanwhile,the number of Brd U-positive and Brd U＋/DCX＋double-labeled cells was lower in the subventricular zone of diabetic rats compared with agematched normal rats.Western blot results revealed downregulated expression of insulin receptorβ,phosphorylated glycogen synthase kinase 3β,and β-catenin in the subventricular zone of diabetic rats.Altogether,these results indicate that diabetes mellitus causes insulin deficiency,which negatively regulates glycogen synthase kinase 3β and enhances β-catenin degradation,with these changes inhibiting neural stem cell proliferation.Further,these signaling pathways affect proliferation and differentiation of neural stem cells in the subventricular zone.Dysfunction of subventricular zone neural stem cells causes a decline in olfactory bulb structural plasticity and impairs olfactory sensitivity in diabetic rats.展开更多
BACKGROUND Apolipoprotein E epsilon 4(APOE4)is recognized as a genetic risk factor for cognitive decline and neurodegeneration in both type 2 diabetes mellitus(T2DM)and Alzheimer’s disease,while glycated hemoglobin(H...BACKGROUND Apolipoprotein E epsilon 4(APOE4)is recognized as a genetic risk factor for cognitive decline and neurodegeneration in both type 2 diabetes mellitus(T2DM)and Alzheimer’s disease,while glycated hemoglobin(HbA1c)reflects persistent hyperglycemia and serves as a key indicator of long-term glycemic control in T2DM.Although both factors have been individually linked to neurobehavioral deficits,it remains uncertain whether HbA1c contributes to APOE4-related cognitive and olfactory impairment in individuals with T2DM.AIM To investigate the role of HbA1c in APOE4-associated cognitive and olfactory dysfunction in patients with T2DM.METHODS Of 636 T2DM patients were recruited from five medical centers in Wuhan,Hubei Province,China.APOE genotyping was evaluated by polymerase chain reaction using Gerard’s method.Cognitive and olfactory functions were assessed by mini-mental state examination and Connecticut chemosensory clinical research center test,respectively.Regression analysis was employed to assess the independent and interactive effects of HbA1c on APOE4-associated cognitive and olfactory function.RESULTS APOE4 was associated with increased risks of cognitive impairment[odds ratios(OR)=1.815,P=0.021]and olfactory dysfunction(OR=2.588,P<0.001).Higher HbA1c levels were also related to worse cognitive(OR=1.189,P<0.001)and olfactory performance(OR=1.149,P=0.011).HbA1c exerted a moderating effect,yet not a mediating effect,between APOE4 and its impacts on cognition and olfaction.Specifically,a higher level of HbA1c exacerbated the damaging effect of APOE4,as shown by significant interaction effects on both cognitive impairment(OR=2.687,P<0.001)and olfactory dysfunction(OR=1.440,P=0.027).CONCLUSION Elevated HbA1c levels are associated with increased risks of cognitive and olfactory impairments in patients with T2DM and may exacerbate the detrimental effects of APOE4.These findings underscore the need for early preventive strategies targeting individuals with both poor glycemic control and APOE4 carriage to mitigate neurodegenerative risk.展开更多
基金partly supported by the National Natural Science Foundation of China,No.81370448,81570725
文摘Sensitive smell discrimination is based on structural plasticity of the olfactory bulb,which depends on migration and integration of newborn neurons from the subventricular zone.In this study,we examined the relationship between neural stem cell status in the subventricular zone and olfactory function in rats with diabetes mellitus.Streptozotocin was injected through the femoral vein to induce type 1 diabetes mellitus in Sprague-Dawley rats.Two months after injection,olfactory sensitivity was decreased in diabetic rats.Meanwhile,the number of Brd U-positive and Brd U＋/DCX＋double-labeled cells was lower in the subventricular zone of diabetic rats compared with agematched normal rats.Western blot results revealed downregulated expression of insulin receptorβ,phosphorylated glycogen synthase kinase 3β,and β-catenin in the subventricular zone of diabetic rats.Altogether,these results indicate that diabetes mellitus causes insulin deficiency,which negatively regulates glycogen synthase kinase 3β and enhances β-catenin degradation,with these changes inhibiting neural stem cell proliferation.Further,these signaling pathways affect proliferation and differentiation of neural stem cells in the subventricular zone.Dysfunction of subventricular zone neural stem cells causes a decline in olfactory bulb structural plasticity and impairs olfactory sensitivity in diabetic rats.
基金Supported by the China Postdoctoral Science Foundation General Program,No.2024M762504the Intramural Research Program of Liyuan Hospital,Tongji Medical College,Huazhong University of Science and Technology,No.2023 LYYYGZRP0004.
文摘BACKGROUND Apolipoprotein E epsilon 4(APOE4)is recognized as a genetic risk factor for cognitive decline and neurodegeneration in both type 2 diabetes mellitus(T2DM)and Alzheimer’s disease,while glycated hemoglobin(HbA1c)reflects persistent hyperglycemia and serves as a key indicator of long-term glycemic control in T2DM.Although both factors have been individually linked to neurobehavioral deficits,it remains uncertain whether HbA1c contributes to APOE4-related cognitive and olfactory impairment in individuals with T2DM.AIM To investigate the role of HbA1c in APOE4-associated cognitive and olfactory dysfunction in patients with T2DM.METHODS Of 636 T2DM patients were recruited from five medical centers in Wuhan,Hubei Province,China.APOE genotyping was evaluated by polymerase chain reaction using Gerard’s method.Cognitive and olfactory functions were assessed by mini-mental state examination and Connecticut chemosensory clinical research center test,respectively.Regression analysis was employed to assess the independent and interactive effects of HbA1c on APOE4-associated cognitive and olfactory function.RESULTS APOE4 was associated with increased risks of cognitive impairment[odds ratios(OR)=1.815,P=0.021]and olfactory dysfunction(OR=2.588,P<0.001).Higher HbA1c levels were also related to worse cognitive(OR=1.189,P<0.001)and olfactory performance(OR=1.149,P=0.011).HbA1c exerted a moderating effect,yet not a mediating effect,between APOE4 and its impacts on cognition and olfaction.Specifically,a higher level of HbA1c exacerbated the damaging effect of APOE4,as shown by significant interaction effects on both cognitive impairment(OR=2.687,P<0.001)and olfactory dysfunction(OR=1.440,P=0.027).CONCLUSION Elevated HbA1c levels are associated with increased risks of cognitive and olfactory impairments in patients with T2DM and may exacerbate the detrimental effects of APOE4.These findings underscore the need for early preventive strategies targeting individuals with both poor glycemic control and APOE4 carriage to mitigate neurodegenerative risk.
