Amyloid Beta Peptide Induces D-serine Dependent NMDAR Dysfunction in the Mouse Hippocampus

.................................................................................................................................... II TABLE OF CONTENTS .............................................................................................................. III LIST OF FIGURES ........................................................................................................................ V ABBREVIATIONS ........................................................................................................................ VI ACKNOWLEDGEMENTS ........................................................................................................ VIII 1 INTRODUCTION ................................................................................................................... 1 1.1 ALZHEIMER’S DISEASE ..................................................................................................................... 1 1.1.1 Histological hallmarks of AD ............................................................................................. 1 1.1.2 Production of Aβ ...................................................................................................................... 3 1.1.3 Mutations involved in AD ..................................................................................................... 4 1.1.4 Hypotheses of AD .................................................................................................................... 6 1.2 N-­‐METHYL-­‐D-­‐ASPARTATE RECEPTORS (NMDARS) .................................................................. 8 1.2.1 Molecular biology of NMDARs .......................................................................................... 9 1.2.2 Expression of NMDARs ...................................................................................................... 11 1.2.3 NMDARs and D-serine ........................................................................................................ 11 1.2.4 NMDAR-mediated excitotoxicity .................................................................................... 13 1.2.5 Aβ-induced NMDAR-dependent excitotoxicity ......................................................... 14 2 OBJECTIVES AND HYPOTHESIS ....................................................................................... 17 3 MATERIALS AND METHODS ............................................................................................ 18 3.1 ANIMALS ......................................................................................................................................... 18 3.2 SLICE PREPARATION ..................................................................................................................... 18 3.3 WHOLE-­‐CELL ELECTROPHYSIOLOGICAL RECORDINGS ............................................................. 19 3.4 7PA2 CHO CELL CULTURE AND Aβ PRODUCTION ................................................................... 20 3.5 Aβ25–35 PREPARATION ................................................................................................................. 21 3.6 ANALYSIS ........................................................................................................................................ 22 4 RESULTS .............................................................................................................................. 23 4.1 SYNAPTIC NMDAR EPSCS ARE DEPRESSED BY SOLUBLE Aβ OLIGOMERS .......................... 23 4.2 SOLUBLE Aβ OLIGOMERS INDUCE A SHIFT IN HOLDING CURRENT .......................................... 24 4.3 TONIC EXTRASYNAPTIC NMDAR FUNCTION IS IMPAIRED IN SRKO MICE ........................... 26 4.4 EVOKED EXTRASYNAPTIC NMDAR EPSCS ARE DEPRESSED IN SOLUBLE Aβ OLIGOMERS 27 5 DISCUSSION ........................................................................................................................ 28 5.1 NATURALLY SECRETED Aβ CAUSES SYNAPTIC NMDAR DYSFUNCTION ............................... 28 5.2 THE EFFECT OF Aβ IS ENHANCED IN SRKO MICE .................................................................... 29 5.3 Aβ25–35 DOES NOT ACUTELY AFFECT SYNAPTIC NMDAR FUNCTIONS ................................. 30