Synapses, spines, zinc and pathology of Alzheimer's disease.

Visual system;Microglia;Senile plaques;Tree shrew;Zincergic;Transgenic model of Alzheimer's

Dmitry Familtsev, 1985-

University:University of Louisville

Department:Anatomical Sciences and Neurobiology

关键词: Visual system;    Microglia;    Senile plaques;    Tree shrew;    Zincergic;    Transgenic model of Alzheimer's;   

Others  :  https://ir.library.louisville.edu/cgi/viewcontent.cgi?article=1419&context=etd

美国|英语

来源: The Universite of Louisville's Institutional Repository

【 摘 要 】

Alzheimer's disease (AD) is a multifactorial illness manifesting as gradual progressive memory loss, culminating in an end-stage of profound cognitive deterioration. While AD pathology is characterized by the presence of beta amyloid (Aß) plaques, clearing Aß deposits from the brain has not proved sufficient to improve cognition. It is thought that the gradual loss of synaptic connections in the telencephalon leads to cognitive impairment. Thus, understanding synaptic function and testing methods to prevent the loss of synapses are the primary directions of current AD research. AD pathology in the primary sensory areas of the cortex (the granular or koniocortex) is typically found only in the most advanced cases. To gain insight into the differences in the synaptic organization of the koniocortex and the eulaminate cortex, we compared the distribution and morphology of geniculocortical and pulvinocortical terminals in tree shrews. Synaptic terminals were labeled using the stereotaxic injection of neuroanatomical tracers or viral vectors, and/or immunohistochemical labeling of the type 2 vesicular glutamate transporter (vGLUT2) and gamma aminobutyric acid (GABA). Transmitted light, confocal and electron microscopy revealed that geniculocortical terminals in layers IVa and IVb of the striate cortex are significantly larger than pulvinocortical terminals in the temporal cortex. Geniculocortical terminals contact nonGABAergic dendritic spines (91%) and the GABAergic dendrites of cortical interneurons (9%), while pulvinocortical terminals only contact nonGABAergic dendritic spines. Geniculocortical terminals often contain small extensions of postsynaptic spines, termed “spinules”, while pulvinocortical terminals do not. Analysis of the postsynaptic targets of geniculocortical terminals revealed that 14% contained a spine apparatus, an organelle related to dendritic spine stability and memory. Our results indicate that the organization of thalamocortical synaptic connections is quite different in the konicortex and eulaminate cortex. Further comparisons of the synaptic organization of the koniocortex and eulaminate cortex may reveal characteristics related to the progression of AD pathology. The brain areas primarily affected by AD are mirrored by the distribution of dendritic spines that contain spine apparati (uniquely identified by the actin-bindng protein synaptopodin) and by glutamatergic terminals that contain zinc ions sequestered by the type 3 zinc transporter (ZnT3). Because zinc assists in the rapid aggregation of Aß, and zinc levels increase and decrease with brain activity, we examined levels of ZnT3 and synaptopodin in the cortex and hippocampus of a transgenic mouse model of AD (TgSwDI; this model expresses neuronally derived human amyloid ß-precursor protein, APP gene, 770 isoform, containing the Swedish K670N/M671L, Dutch