*G. LAZARO-MUNOZ, V. MAHADOMRONGKUL, C. K. CAIN, C. J. AOKI;
Ctr Neural Science, New York Univ, New York City, NY.

The trafficking of GluR1 subunit-containing AMPA receptors to the synapse is thought to underlie the enhanced synaptic efficacy observed after long-term potentiation and associative learning (Rumpel et al., 2005). Fear conditioning, where an animal learns that a conditioned stimulus (CS, tone) is a predictor of an upcoming unconditioned stimulus (US, footshock), was used to examine the ultrastructural localization of AMPA receptor subunit GluR1 in the lateral amygdala (LA) shortly after learning. LA is a critical site for the acquisition and storage of this type of CS-US association (LeDoux, 2000). Three groups of animals were compared: paired group (P) which received three presentations of the CS co-terminated with the US, an unpaired group (UP) which received the same amount of CS and US in a temporally unpaired fashion, and a naive group (N) that was placed in the conditioning chamber but did not receive any CS or US presentation. Animals were sacrificed and perfused 40 minutes after the last stimulus presentation. The ultrastructural localization of GluR1 was examined using electron microscopy. Our results show higher GluR1 subunit immunoreactivity at the postsynaptic density (PSD) of LA spines in the P (mean = .75) compared to both UP (mean = .50) and N (mean = .51), F(2, 379) = 3.18, p < .05. Furthermore, no differences were observed in the level of immunoreactivity near or away from the PSDs in the spines, nor did we observe differences in the level of immunoreactivity for the GluR1 antibody on presynaptic terminals. These in vivo data support the idea that GluR1 trafficking to the synapse underlies the early phase of learning.
Support Contributed By: P30EY13079, P30EY13079, RO1 NS41091, RO1 NS41091, R01 13145, R01 13145


Program No. 431.7/D50
Poster presentation:Monday, Oct 16, 2006, 3:00 PM - 4:00 PM
Location: Georgia World Congress Center: Halls B3-B5