[Abstract Title]. - Society for Neuroscience

Abstract: Here we describe the discovery of a novel protein, cadeprin, which elicits a reliable
and particularly profound long-term depression (LTD) in the CA1 area of the adult rat
hippocampus. This protein was subsequently purified and identified as a new member of the
chymotrypsin-like S8A serine protease family, several members of which were also tested and
found to induce LTD by virtue of their proteolytic activity.
The LTD induced was not blocked by NMDA antagonists and could not be occluded by the
induction of NMDA receptor-dependent LTP. However, it was prevented and reversed by Group
I mGluR antagonists indicating that this is a mGluR dependent form of LTD. Interestingly,
during the initial perfusion of the protease no changes in baseline synaptic strength were
observed that would be expected with the primary activation of the metabotropic glutamate
receptor (mGluR). Intriguingly, this LTD protocol, whilst it is dependent on mGluRs for its
expression it is not dependent on activating them during its induction. We speculate that this
protease protocol circumvents the initial steps in agonist-induced mGluR LTD and act as a
downstream mediator. Perhaps making specific structural modifications of dendritic spines and
their associated postsynaptic densities (PSDs) leading to decreased synaptic strength. The
emergence of this late stage protocol for inducing LTD without the contaminating influence of
early stage factors may prove a very useful tool in investigating LTD.
Disclosures: A.P. Mallon, None; D.G. MacGregor, None; T.W. Stone, None; H.G. Nimmo,
None.
Poster
238. LTD: Hippocampus and Cortex
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 238.15/D60
Topic: B.08.f. Long-term depression ( LTD )
Support: NIH grant NS048406
Title: Dynamic imaging of cyclic nucleotide concentration changes during long-term activitydependent
synaptic plasticity using fluorescent sensors
Authors: *Z. ZHOU 1 , X. L. ZHANG 1 , C. UPRETI 1 , V. O. NIKOLAEV 2 , P. K. STANTON 1 ;
1 Dept Cell Biol/Anatomy, New York Med. Coll, Valhalla, NY; 2 Inst. of Pharmacol. and
Toxicology, Würzburg, Germany
Abstract: The cyclic nucleotide second messengers cAMP and cGMP play important roles in
both presynaptic and postsynaptic long-term activity-dependent synaptic plasticity at a variety of
synapses. Previously, our lab has shown that pairing elevation of [cGMP] with suppression of the