RESUMO
The authors studied hippocampal microscopic sections taken from transgenic mice expressing non-mutated human amyloid precursor protein (APP695), and age-matched non-transgenic control mice. The aim of the study was to reveal individual effects of plaque-like amyloid of aged (25.5 months) transgenic mice and diffuse amyloid of non-transgenic mice (verified by immunohistochemistry and Congo Red fluorescence) on synaptic plasticity. In vitro extracellular recording of excitatory postsynaptic potentials from hyppocampal CA1 area revealed impairment of input/output characteristics and long-term potentiation, and a several-millisecond delay of initial post-tetanic traces in aged transgenic vs. control mice. The results show that amyloid plaques (not diffuse amyloid) may be one of the causes of synaptic dysfunction in Alzheimer disease.