Synaptotagmin and synaptic transmission alterations in apolipoprotein E-deficient mice

1. Aged apoE-deficient mice and age-matched controls were tested for cognit ive alterations in the Morris water maze. 2. Water maze results were correlated with in vivo electrophysiology and ex pression of the synaptic protein synaptotagmin (p65). 3. Compared to age-matched controls, apolipoprotein E-deficient mice displa yed significant performance impairment accompanied by in vivo electrophysio logical alterations in the dentate gyrus. 4. Apolipoprotein B-deficient mice also showed a significant increase in th e synaptic protein, synaptotagmin, a synaptic calcium sensor involved in ne urotransmitter release. 5. Cognitive impairments in these animals may be associated with decreased synaptic excitability in hippocampal neurons and the regulatory role of apo lipoprotein E in synaptic function might be mediated by modulation of the e xpression of calcium sensor proteins.