[Abstract Title]. - Society for Neuroscience

in either dentate gyrus or CA fields. In contrast, at 6 months of age, there was a strong trend
towards a decrease (-35%) of the GAD-IR neurons in the CA fields of transgenic mice compared
to their wild-type counterparts. No such trend was observed in the dentate gyrus. Given that a
three-fold increase in hippocampal Aβ burden (reflecting extracellular Aβ accumulation) was
observed in 6 months old compared to 4 monts old transgenic animals, these results suggest an in
vivo relationship between Aβ levels and hippocampal interneuron vulnerability.
Disclosures: S.M. Krantic , None; N. Mechawar, None; M. Davoli, None; O. Gubkina,
None; J. Brouillette, None; J. Chabot, None; R. Quirion, None.
Poster
244. Abeta Toxicity I
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 244.12/M5
Topic: C.01.c. Abeta toxicity
Support: American Health Assistance Foundation
University of Arizona
Title: Aβ1-42 and the endocytosis of AMPA-type glutamate receptors in cultured hippocampal
neurons
Authors: *P. A. ST JOHN;
Dept Cell Biol & Anat., Univ. Arizona Col. Med., Tucson, AZ
Abstract: Amyloid-beta (Aβ) peptides are the primary constituents of amyloid plaques in the
brain in Alzheimer's disease (AD). A great deal of evidence supports the conclusion that Aβ
peptides cause AD, but how they do so is not clear. Aβ peptides spontaneously aggregate, or
self-assemble, to generate distinct macromolecular forms. In considering the range of molecular,
cellular, and cognitive abnormalities observed in AD, in AD-model animals, and in neurons
exposed to Aβ, it appears that different deficits may be caused by different assembly forms of
Aβ, rather than all stemming from a single proximate cause. For example, recent evidence from
our lab and others indicates that fibrillar forms of Aβ1-42 (Aβ42) selectively activate apoptotic
pathways in CNS neurons, that is, they may be considered "neurotoxic," while several groups
have provided evidence that less aggregated, soluble forms of Aβ are more "synaptoxic," that is,
they more potently interfere with synaptic function, including synaptic plasticity, and even
synaptic survival. This dichotomy of functional effects of different Aβ assembly forms is
consistent with the suggestion that fibrillar and soluble forms of Aβ42 bind to different