Effects Of Transient Receptor Potential Channel7(TRPM7) On The Learning And Memory Deficits Induced By Amyioidbeta-peptide(25-35) In Rats And Its Preliminary Mechanism Research

Alzheimer’s disease (AD) is a degenerative disease, insidious, ultimately fatalneurodegenerative disease of the brain and the most common type of progressivecognitive impairment and memory loss that occurs predominantly in the elderlypopulation. It has four major defining indicators: neurofibrillary tangles (NFTs) in thecortex and hippocampus made of hyperphosphorylated tau proteins together withactivation of local inflammatory responses, extracellular amyloid plaque formation,reactive gliosis. Neurofibrillary tangles. The pathogenesis of AD is unclear and short ofefficient cure measures. Looking for the pathophysiological process and newtherapeutic strategies of AD is one of the focal points of prevention and cure thedisease.Inflammatory response is a critical cause in the pathogenesis of Alzheimers’sdisease (AD). Inflammatory mediators promote the occurrence and development of AD.In the progression of AD,it has been demonstrated that accumulation and aggregation ofAβ peptide in the hippocampus of the brain usually results in the activation of glial cellswhich,in turn,and initiates a neuroinflammatory response, involving reactive oxygenintermediates and inflammatory cytokines,including interleukin(IL)-1β,IL-6,and tumornecrosis factor(TNF-α). It may attenuate the damage of nerve cells and improvelearning and memory ability by inhibiting inflammatory response in the progression ofAD. risk rate for the incidence of AD.Studies have shown that ion channel protein can regulate the inflammatory response and influence the secretion of inflammatory cytokines.The transient receptor potential melastatin7channel(TRPM7) is a Mg2+-and Ca2+-permeable ion channel covalently coupled to analpha-type Ser/Thr protein kinase domain. TRPM7is expressed in brain,kidney,smooth,liver and so on. TRPM7has been found to play a key role in the death ofanoxic neurons,cerebral ischemia/reperfusion, hepatic fibrosis(HF), familialAlzheimer’s disease（FAD）.The relationship between TRPM7and inflammatory factorin disease is not clear. And the role of TRPM7in AD has not yet been reported. Thisexperiment investigates the relationship between transient receptor potential channel7(TRPM7) and inflammatory factor in Alzheimer’s disease.Main content is as follows:Aggregated Aβ25-35peptide was injected stereotactically into the hippocampal CA1region of both hemisphere to construct Alzheimer’s disease.Through the Behaviorexamination(MWM) and Histological examination including HE staining andimmunohistochemical to determine whether the model is set up successfully.Expressions of TRPM7、TNF-α mRNA in hippocampus were analyzed by RT-PCR.Expressions of TNF-α protein in hippocampus were analyzed by Western blot. Andfurther stimulate SH-SY5Y cells with Aβ25-35to constructe Alzheimer’s disease in vitro.Then MTT method was used for determination the best effective concentration and timepoint of Aβ25-35-stimulated SH-SY5Y cells. And the sequence of TRPM7siRNA waschemically synthesized. The siRNA was transfected into SH-SY5Y cells usingLipofectamineTM2000to down-regulate TRPM7gene. Expressions of TRPM7、NF-κB、IL-6、TNF-α mRNA were analyzed by RT-PCR. Lactic acid dehydrogenase (LDH) kitwas used to determine the lactate dehydrogenase (LDH) content of cell supernatant.Theconcentration of TNF-α and IL-6in Cell supernatant was assayed by ELISA. Theresults showed as follows: TRPM7、TNF-α mRNA expression increased significantly inthe hippocampus of model group rats comparing with the control group and NS group.SH-SY5Y cell transfected with siRNA, TRPM7、 NF-κB、 IL-6、 TNF-α mRNA expression decreased significantly comparing with the model group.And expressions ofcell supernatant of TNF-α and IL-6content were also decreased significantly. Theseresults show that, TRPM7、TNF-α mRNA expression increased significantly in thehippocampus of model group rats; Targeted inhibition of TRPM7gene by siRNAinterference,which can down-regulate the expression of inflammatory factors,such asTNF-α、IL-6. This process may be accomplished by inhibiting the activation of NF-κBsignal pathway,and the the expression of inflammatory factors weredown-regulated.And then reduced the cytotoxicity on SH-SY5Y cells induced byβ-amyloid peptide.