[Abstract Title]. - Society for Neuroscience

Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 238.7/D52
Topic: B.08.f. Long-term depression ( LTD )
Support: FORUN, Univ Rostock Med Faculty
Title: MGluR-dependent LTD at schaffer collateral-CA1 synapses is enhanced by HCN channel
inhibition
Authors: *T. KIRSCHSTEIN, T. TOKAY, M. ROHDE, R. E. KOHLING;
Dept Physiol, Univ. Rostock, Rostock, Germany
Abstract: HCN channels are widely expressed in hippocampal pyramidal cells, and play a
fundamental role in regulating the synaptic function. Here, we studied the involvement of HCN
channels in basal synaptic transmission, short-term plasticity and the induction of metabotropic
glutamate receptor-dependent long-term depression (mGluR-LTD) by bath application of (RS)-
3,5-dihydroxyphenylglycine (DHPG) at Schaffer collateral-CA1 synapses using field excitatory
postsynaptic potential recording techniques. Brief application of DHPG (100 µM, 10 min)
caused a strong depression of CA1 fEPSPs resulting in stable LTD accompanied by an increase
in the paired-pulse ratio (PPR) suggesting a presynaptic mechanism. When the slices were
bathed with the HCN channel blocker ZD7288 (10 µM), a substantial increase in the fEPSP
amplitude and a significant decrease in the PPR were observed. However, pre-treatment of
ZD7288 significantly enhanced the DHPG-induced LTD, and the concomitant increase of the
PPR was significantly higher than the PPR increase following DHPG without ZD7288 pretreatment.
In addition, we observed an intermediate and strong enhancement of DHPG-induced
LTD in heterozygous (HCN1+/-) and homozygous (HCN1-/-) mutants, respectively. In contrast,
NMDA receptor-dependent LTD induced by low-frequency stimulation was not significantly
altered in the HCN1-deficient mice. These results suggest a constraining effect of HCN1
channels on Schaffer collateral-CA1 mGluR-dependent but not NMDA receptor-dependent LTD.
Disclosures: T. Kirschstein , None; T. Tokay, None; M. Rohde, None; R.E. Kohling, None.
Poster
238. LTD: Hippocampus and Cortex
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 238.8/D53
Topic: B.08.f. Long-term depression ( LTD )