[Abstract Title]. - Society for Neuroscience

of synaptic plasticity in the lateral pathway. Our results show that in young animals, both lateral
and medial afferents show paired-pulse facilitation and therefore appear to have a lower release
probability than was initially suspected. In addition, we found that 1 Hz stimuli effectively
induced large LTD in this pathway, while stimuli at 3-5Hz were less efficacious. LTP could be
reliably induced with high-frequency stimulation (100 Hz). These findings help to further define
the basic electrophysiological characteristics of this hippocampal afferent, and help to lay the
groundwork for future studies on how drugs of addiction might alter its function.
Disclosures: R. Petersen , None; B. Christie, None.
Poster
238. LTD: Hippocampus and Cortex
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 238.17/D62
Topic: B.08.f. Long-term depression ( LTD )
Support: NIH Grant AA014691
NIH Grant AA09675
Title: Long-term synaptic depression that is associated with GluR1-S845 dephosphorylation but
not AMPA receptor internalization
Authors: *K. D. DAVIES 1 , S. M. GOEBEL-GOODY 2 , S. J. COULTRAP 1 , M. D.
BROWNING 1 ;
1 Pharmacol., 2 Neurosci., Univ. of Colorado HSC, Aurora, CO
Abstract: Long lasting changes in the strength of synaptic transmission in the hippocampus are
thought to underlie certain forms of learning and memory. Accordingly, the molecular
mechanisms that account for these changes are heavily studied. Post-synaptically, changes in
synaptic strength can occur by altering the amount of neurotransmitter receptors at the synapse or
by altering the functional properties of synaptic receptors. In this study, we examined the
biochemical changes produced following chemically induced long-term depression in acute
hippocampal CA1 minislices. Using three independent methods, we found that this treatment did
not lead to an internalization of AMPA receptors. Furthermore, when the plasma membrane was
separated into synaptic membrane-enriched and extra-synaptic membrane-enriched fractions, we
actually observed a significant increase in the concentration of AMPA receptors at the synapse.
However, phosphorylation of S845 on the AMPA receptor subunit GluR1 was significantly
decreased throughout the neuron, including in the synaptic membrane-enriched fraction.