Effects Of Triptolide On The Expression Of Collybistin And Gephyrin In Alzheimer’s Disease Synapses And Related Mechanisms

Background: Alzheimer’s disease,which is a common neurodegenerative disease with Aβ amyloid plaque deposition and hyperphosphorylated Tau protein tangle as pathological manifestations,memory loss,intellectual disability,and behavioral abnormalities as clinical manifestations,it has a high pathogenicity rate and a high disability rate,which is a great burden on society,but there is no cure for drugs so far.Triptolide is an epoxide diterpene lactone compound isolated from Tripterygium wilfordii.Studies have shown that it has a neuroprotective effect,but the specific effects and related mechanisms of Alzheimer’s disease are not known at present.Gephyrin（Gep）and Collybistin（Cb）are two important components of the postsynaptic protein skeleton network of inhibitory neural synapse GABAAR,and GABAAR is involved in the pathogenesis of AD and plays an important role in it.However,the changes of Gephyrin and Collybistin expression in AD are not yet clear.Objective: This study explored the effects of Triptolide on the expression of Collybistin and Gephyrin in Alzheimer’s disease synapses and related mechanisms,providing a theoretical basis for finding potential drug targets for the treatment of AD.Methods: Thirty healthy 8-week old male C57BL/6J mice were randomly divided into control group（n = 10）,model group（n = 10）and triptolide group（n = 10）.Amyloid-β（Aβ）42 was injected into the bilateral ventricles of mice in the model group,and the same amount of saline was injected as the control group.Triptolide was injected intraperitoneally daily after Aβ42 was injected（a total of 30 days）in the triptolide group.Their learning and memory were tested by Morris water maze.The deposition of Aβ42in the hippocampus was detected by immunohistochemical staining.Gephyrin,Collybistin and GABAAR,three synaptic associated proteins,in the hippocampus were detected by Western blotting.Furthermore,we used ELISA to detect the proinflammatory cytokines including tumor necrosis factor α and IL-1β in the blood.Moreover,SOD,MDA and GSH were measured by corresponding kits.Results: Water maze test results showed that triptolide improved learning and spatial memory in AD-like mice.Immunoimprinting assay showed that the expression levels of Gephyrin,Collybistin and GABAAR were down-regulated in AD.Triptolide increased the expression levels of Gephyrin（P < 0.01）,Collybistin（P < 0.01）and GABAAR（P < 0.001）.immunohistochemical assay showed that triptolide decreased the expression of Aβ in AD-like mice（P<0.01）.In addition,enzyme-linked immunoassay showed that triptolide decreased the expression of inflammatory cytokines TNF-α（P<0.05）and IL-1β（P < 0.01）in AD mice,suggesting that triptolide may have anti-inflammatory effects in AD.In addition,triptolide significantly up-regulated the expression of SOD（P<0.05）and GSH（P<0.05）,and significantly down-regulated the expression level of MDA（P <0.01）,suggesting that triptolide may reduce oxidative damage in AD.Conclusion: In AD,the expression levels of Gephyrin,Collybistin and GABAAR were all down-regulated.Triptolide can up-regulate the expression levels of GABAAR and its stable postsynaptic structures Gephyrin and Collybistin,and also has the effects of scavenging Aβ,anti-inflammatory and Antioxidant stress damage.Gephyrin and Collybistin may be potential therapeutic targets.