The Distribution And Expression Of ZnTs And Zinc Ions In The Cerebellum Of APP/PS1 Transgenic Mouse

The major pathological hallmarks of Alzheimer's disease(AD) are the presence of senile plaques containing abundant amyloid beta peptide(AP),neurofibrillary tangles(NFT) and cerebral amyloid angiopathy(CAA).Aβis the key factor in the pathologic process of AD and generated from the amyloid precursor protein(APP) by proteolytic processes ofβ- andγ-secretase.Recent experimental studies have supported the notion that increased zinc intake increases the amount of Aβaggregations in APP transgenic mouse brains.Metal chelating agents have been shown to inhibit the formation of amyloid plaques in APP transgenic mouse brains. Zinc is essential for development,growth,DNA synthesis,immunity,and a wide array of other cellular processes.Zinc cannot travel across biological membranes by passive diffusion.Specific membrane transporters and channels are believed to be involved in its transfer and metabolism.Zinc transporter(ZnTs) is one of the important protein family involved in zinc metabolism in the brain.Recently,it has been reported that there are significant alterations in the expression of ZnT1,ZnT3-7 in AD patient and APP/PS1 transgenic mouse brains.Genetic ablation of ZnT3 in the Tg2576 Alzheimer mouse model inhibits the formation of amyloid plaques and CAA,indicating the roles of ZnT and zinc ions in the pathologic process of AD.Recently,a clinical study has shown that the cerebellar amyloid plaques were found in 31 of the 57 cases(52%). However,the expression of ZnTs in the cerebellum of AD brain has not been investigated.Therefore,in the present study,we invistigated the distribution and expression of ZnT proteins and zinc ions in the cerebellum of APP/PS1 transgenic mouse,to further understand the zinc metabolism and its correlation to the pathophysiological mechanism of AD. MethodsThe level and distribution of free/loosely bound zinc ions were evaluated by in vivo selenium autometallography.The distribution patterns of ZnTs in the cerebellums and the positional relation between ZnTs and Aβwere detected by double immunofluorescence and confocal laser scanning microscopy.The changes of ZnTs expression levels in the APP/PS1 transgenic mouse cerebellum were studied by Western blot analyses.Results1,Distribution of zinc ions in the cerebellar cortex of APP/PS1 transgenic mouseAMG results showed that AMG-positive plaques were widely distributed in the cerebellar cortex of APP/PS1 transgenic mouse.It is more widely present in the molecular layers than any other cortex.Brown black AMG positive reaction products could be seen clearly in the vascular wall and its surrounding.2,ZnTs were expressed in most of the Aβcontaining plaquesImmunohistochemimistry results revealed that an abundant distribution of senile plaques with varying density and intensity in the different layers of the cerebellar cortex was seen.The most intensive fluorescence was found in the molecular layers. ZnTs were expressed in most of the Ap containing plaques.Aβand ZnTs protein were co-expressed in the senile plaques.3,Altered expression of ZnTs in the cerebellar of APP/PS1 transgenic miceWestern blot results indicated that the expression of ZnTs proteins was increased significantly in the cerebellar cortex of APP/PS1 transgenic mice.Conclusion1,In APP/PS1 mouse cerebellum,the rosette-formed AMG-positive plaques can be seen in the cerebellar cortex,the plaques were found to be more widely present in the molecular layers.2,Zinc ions are abundantly distributed in the cerebellum of APP/PS1 transgenic mice. 3,Aβand ZnTs protein were co-expressed in the senile plaques in the cerebellum of APP/PS1 transgenic mice.4,The expression of ZnTs proteins was increased in the cerebellar cortex of APP/PS1 transgenic mice.5,Zinc ions and ZnTs are involved in the formation of senile plaques in the cerebellar cortex of APP/PS1 transgenic mice.