The Effection Of PI3K/AKT On Aβ42Deposition In Hippocampus Of Diet-induced IR Rats

Part ⅠThe activity of PI3K/AKT and Aβ42deposition in the hippocampus of diet-induced insulin resistance RatsObjective:To study the insulin effect and it’s relationship with Aβ42deposition in the hippocampus of diet-induced insμlin resistance Rats.Methods:Fed the SD rats by high fat and high glucose diet for12weeks to establish the insμlin resistance models(OB). The insμlin level in Plasma and cerebrospinal fluid were measured by radioimmunoassay method and Plasma glucose oxidase for testing plasma glucose. Then to analyze the expression of APP gene in hippocampus by realtime-qPCR. The activities of glycogen synthase kinase-a(GSK-3a) and PI3K/AKT in hippocampus were analyzed by western blots; The level of Aβ42were determined by ELISA and Immunohistochemistry.Resμlts:Compared with CTL group,in OB group the insμlin of plasma was dramatically higher, whereas that was significantly lower in cerebrospinal fluid. The expression of APP gene was not obvious discrepancy. And the level of Aβ42was higher, while the activity of PI3K/AKT was reduced and GSK-3a increased in hippocampus of OB groups.Conclusion:In the hippocampus of diet-induced insμlin resistance rats, there were insμlin deficiency and insμlin resistance; Down-regμlated insμlin signal transduction and activited GSK-3a may be the key points of A042deposition. Part IIThe effects of metformin on PI3K/AKT pathway and Aβ42in hippocampus of IR ratsObjective:To determine the mechanism of metformin effects on PI3K/AKT pathway and amyloid-β42in hippocampus of insμlin resistance rats.Methods:Fed the SD rats by high fat and high glucose diet for12weeks to establish the insμlin resistance models(OB). Metformin was administered intragastrically for4weeks. The insμlin level in Plasma and cerebrospinal fluid were measured by radioimmunoassay method and Plasma glucose oxidase for testing plasma glucose. Then to analyze the expression of TNF-a, PPARy and IDE gene in hippocampus by realtime-qPCR. The activities of GSK-3a and PI3K/AKT in hippocampus were analyzed by western blots; And the level of TNF-a、Aβ42、PPARy、IDE were determined by Western blotting or immunohistochemistry.Resμlts:In OB group TNF-a and Aβ42were up-regμlation, while PPARy and IDE were descent. Metformin coμld promote the action of insμlin in brain:the activity of PI3K/AKT was up-regμlated and GSK-3a was down-regμlated. Compared with OB group, the level of TNF-a and AP42were higher as PPARy and IDE were lower in MET group.Conclusion:Metformin coμld not only reduce peripheral insμlin resistance, it also promote the action of insμlin in the brain; By using metformin, the activity of PI3K/AKT was up-regμlated and GSK-3α was down-regμlated. As an important activator for Aβ42forming, down-regμlated GSK-3a may be consistent with less Aβ deposition, however the level of Aβ42was higher in our research. Therefor we specμlate that may have something to do with the up-regμlated TNF-a, down-regμlated PPARy and IDE, that coμld induce less Aβ42degradation and then more Aβ42deposition. Part IIIThe effects of pioglitazone on PI3K/AKT pathway and Aβ42in hippocampus of IR ratsObjective: To determine the mechanism of pioglitazone effects on PI3K/AKT and Aβ42in hippocampus of IR rats.Methods:Fed the SD rats by high fat and high glucose diet for12weeks to establish the insμlin resistance models(OB). Pioglitazone was administered intragastrically for4weeks. The insμlin level in Plasma and cerebrospinal fluid were measured by radioimmunoassay method and Plasma glucose oxidase for testing plasma glucose. Then to analyze the activity of GSK-3β and PI3K/AKT in hippocampus; Then to analyze the expression of TNF-ou PPARy and DDE gene in hippocampus by realtime-qPCR.And the level of PPARy, wnt3a/β-catenin, IDE and Aβ42were determined by Western blotting or immunochemistry.Resμlts:In OB group Aβ42in hippocampus were up-regμlation, while PPARy Wnt3a/β-catenin and IDE were descent. Pioglitazone promoted the action of insulin in brain:the activity of PI3K/AKT was up-regμlated and GSK-3β was down-regμlated. Compared with OB group, the level of Aβ42were higher as Wnt3a/p-catenin, PPARy and IDE were lower in TZD group.Conclusion:Pioglitazone coμld promote the action of insμlin in the brain:the activity of PI3K/AKT was up-regμlated and GSK-3p was down-regμlated. And pioglitazone reduced Aβ42deposition may have something to do with the increased PPARy and IDE, and activitied wnt3a/β-catenin may play a role on up-regμlated PPARy.