? Neuronal?Ca2+?signaling?through?endoplasmic?reticulum?(ER)?localized?inositol?trisphosphate?(IP3R)?and? ryanodine?receptors?(RyR)?must?be?tightly?regulated?to?maintain?cell?viability,?both?acutely?and?over?the? lifetime?of?an?organism.??Exaggerated?ER?Ca2+?release?(up?to?4?fold)?has?been?associated?with?Alzheimer?disease? (AD)?mutations?expressed?in?cell?cultures?and?young?mice,?but?little?is?known?of?Ca2+?dysregulations?during? the?normal?and?pathological?aging?processes?using?adult?and?aged?models.?The?hypothesis?is?that?early? intracellular?Ca2+?dysregulation?represents?a?unique??calcium?opathy??that?contributes?to?later?progression?of? AD,?and?is?not?an?acclerated?component?of?normal?aging.??Aim?I?of?this?study?will?determine?and?differentiate? the?distinct?roles?of?neuronal?IP3?and?Ry?Ca2+?channels?in?a?non?transgenic?control?mouse?and?the?3xTg?AD? mouse?model?of?AD.??Aim?II?will?analyze?the?effects?of?age?and?AD?mutations?on?the?magnitude?of?the? exaggerated?ER?Ca2+?signals,?determine?downstream?effects?on?electrophsyiological?membrane?properties?and? synaptic?activity,?and?parse?the?contributions?of?PS1,?APP,?and?tau?mutations?by?comparing?3xTg?AD,? APP/Tau,?PS1KI?and?NonTg?control?mice.??Aim?III?will?seek?to?pharmacologically?reverse?the?exaggerated?ER? Ca2+?release?in?the?3xTg?AD?neurons?and?measure?effects?on?amyloid?plaque?deposition.??Likewise,?amyloid? plaques?will?be?cleared?in?older?3xTg?AD?mice?using?immunotherapy?techniques,?and?establish?if?there?is?a? functional?relationship?between?the?early?Ca2+?dysregulation?and?AD?histopathology.?These?studies?combine? electrophysiological?recording?in?brain?slices,?2?photon?Ca2+?imaging,?and?flash?photolysis?of?caged?compounds? from?control?(non?transgenic),?3xTg?AD,?APP/Tau?and?PS1KI??mice?at?young,?adult,?and?old?ages.? Immunohistochemical?techniques?will?be?used?to?map?and?quantify?changes?in?the?expression?of?IP3R?and?RyR? subtypes,?and?extent?of?AD?histopathology.??These?findings?will?elucidate?intracellular?signaling?changes?and? downstream?effects?on?neuronal?physiology?that?occur?both?in?normal?aging,?and?in?neurodegenerative? disorders?such?as?AD.??? Narrative: The objective of this study is to determine the functional relationship between early changes in neuronal Ca2+ signaling, and later pathophysiology associated with aging and Alzheimer's disease (AD). The results of this study will have scientific and clinical relevance by differentiating between neuronal signaling changes associated with normal aging and those associated with AD pathogenesis. Benefits to public health include the prospect for earlier AD diagnosis and novel therapeutic intervention, long before the onset of cognitive decline and irreversible histopathology.
