Project description:Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. So far, there is no effective treatment for this condition. Tetramethylpyrazine (TMP) is an alkaloid extracted from traditional Chinese medicine chuanxiong, which is mainly used in the treatment of ischemic stroke some related diseases. In this study, we studied the potential effects of TMP on AD progression by using two AD mouse models. 8-month-old 3xTg-AD mice received TMP treatment (10mg/kg/d) for 1 month, and 4-month-old APP/PS1-AD mice received TMP treatment (10mg/kg/d) for 2 months. The behavioral tests by step-down passive avoidance test (SDA), new object recognition (NOR) and Morris water maze (MWM) showed that TMP significantly improved the learning and memory impairment of two AD transgenic mice. In addition, TMP reduced Aß levels and tau phosphorylation. Venny analysis showed that 116 differentially expressed proteins were commonly changed in 3xTg mice vs WT mice and TMP treated mice vs untreated mice. The same, 130 differentially expressed proteins were commonly changed in APP/PS1 mice vs WT mice and TMP treated mice vs untreated mice. The functions of the common proteins modified by TMP in the two models were mainly related to mitochondrial function, synaptic function, cytoskeleton, GTP binding, ATP binding. Mitochondrial omics analysis revealed 21 and 20 differentially expressed mitochondrial proteins modified by TMP in 3xTg-AD mice and APP/PS1 mice, respectively. These differential proteins were located in mitochondrial inner membrane, mitochondrial outer membrane, mitochondrial gap and mitochondrial matrix, and the function of some proteins is closely related to oxidative phosphorylation of (OXPHOS). Western-blot further validated that TMP changed the expression of OXPHOS complex proteins (sdhb, ndufa10, uqcrfs1, cox5b, atp5a) in the hippocampus of the two AD mice. Taken together, our study demonstrated that TMP improved the cognitive impairment and AD-like pathology, and modified hippocampal proteome in the two AD mice models. The improvement of the behavioral and pathology might be associated with modification of mitochondrial protein profile by TMP. Our study suggested that TMP had the potential for the treatment of AD.

Project description:BackgroundCurrently, there is no cure for Alzheimer's disease (AD). Therapeutics that can modify the early stage of AD are urgently needed. Recent studies have shown that the pathogenesis of AD is closely regulated by an endo/lysosomal asparaginyl endopeptidase (AEP). Inhibition of AEP has been reported to prevent neural degeneration in transgenic mouse models of AD. However, more than 90% of AD cases are age-related sporadic AD rather than hereditary AD. The therapeutic efficacy of AEP inhibition in ageing-associated sporadic AD remains unknown.MethodsThe senescence-accelerated mouse prone 8 (SAMP8) was chosen as an approximate model of sporadic AD and treated with a selective AEP inhibitor,: δ-secretase inhibitor 11. Activation of AEP was determined by enzymatic activity assay. Concentration of soluble amyloid β (Aβ) in the brain was determined by ELISA. Morris water maze test was performed to assess the learning and memory-related cognitive ability. Pathological changes in the brain were explored by morphological and western blot analyses.ResultsThe enzymatic activity of AEP in the SAMP8 mouse brain was significantly higher than that in the age-matched SAMR1 mice. The half maximal inhibitory concentration (IC50) for δ-secretase inhibitor 11 to inhibit AEP in vitro is was around 150 nM. Chronic treatment with δ-secretase inhibitor 11 markedly decreased the brain AEP activity, reduced the generation of Aβ1-40/42 and ameliorated memory loss. The inhibition of AEP with this reagent not only reduced the AEP-cleaved tau fragments and tau hyperphosphorylation, but also attenuated neuroinflammation in the form of microglial activation. Moreover, treatment with δ-secretase inhibitor 11 prevented the synaptic loss and alleviated dendritic disruption in SAMP8 mouse brain.ConclusionsPharmacological inhibition of AEP can intervene and prevent AD-like pathological progress in the model of sporadic AD. The up-regulated AEP in the brain could be a promising target for early treatment of AD. The δ-secretase inhibitor 11 can be used as a lead compound for translational development of AD treatment.

Project description:Alzheimer's disease (AD), one of the most common neurodegenerative diseases, has no effective treatment. We studied the potential effects of tetramethylpyrazine (TMP), an alkaloid in the rhizome of Ligusticum chuanxiong Hort. used in Traditional Chinese Medicine (chuānxiong) to treat ischemic stroke, on AD progression in two AD mouse models. Eight-month-old 3xTg-AD mice received TMP treatment (10 mg/kg/d) for 1 month, and 4-month-old APP/PS1-AD mice received TMP treatment (10 mg/kg/d) for 2 months. Behavioral tests, including step-down passive avoidance (SDA), new object recognition (NOR), Morris water maze (MWM), and Contextual fear conditioning test showed that TMP significantly improved the learning and memory of the two AD-transgenic mice. In addition, TMP reduced beta-amyloid (Aß) levels and tau phosphorylation (p-tau). Venny map pointed out that 116 proteins were commonly changed in 3xTg mice vs. wild type (WT) mice and TMP-treated mice vs. -untreated mice. The same 130 proteins were commonly changed in APP/PS1 mice vs. WT mice and TMP-treated mice vs. -untreated mice. The functions of the common proteins modified by TMP in the two models were mainly involved in mitochondrial, synaptic, cytoskeleton, ATP binding, and GTP binding. Mitochondrial omics analysis revealed 21 and 20 differentially expressed mitochondrial proteins modified by TMP in 3xTg-AD mice and APP/PS1 mice, respectively. These differential proteins were located in the mitochondrial inner membrane, mitochondrial outer membrane, mitochondrial gap, and mitochondrial matrix, and the function of some proteins is closely related to oxidative phosphorylation (OXPHOS). Western-blot analysis confirmed that TMP changed the expression of OXPHOS complex proteins (sdhb, ndufa10, uqcrfs1, cox5b, atp5a) in the hippocampus of the two AD mice. Taken together, we demonstrated that TMP treatment changed the hippocampal proteome, reduced AD pathology, and reduced cognitive impairment in the two AD models. The changes might be associated with modification of the mitochondrial protein profile by TMP. The results of the study suggest that TMP can improve the symptoms of AD.

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Inhibition of delta-secretase improves cognitive functions in mouse models of Alzheimer's disease.

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Inhibition of delta-secretase improves cognitive functions in mouse models of Alzheimer's disease.

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