Activation of mGlu receptors induces LTD without affecting postsynaptic sensitivity of CA1 neurons in rat hippocampal slices.
Two forms of long-term depression (LTD) of excitatory synaptic transmission have been identified in the mammalian CNS, which are induced by the synaptic activation of N-methyl-D-aspartate (NMDA) and metabotropic glutamate (mGlu) receptors, respectively. The mGlu receptor-dependent form of LTD can be activated by application of 3,5-dihydroxyphenylglycine (DHPG), a group I selective mGlu receptor agonist. DHPG-induced LTD is increasingly being used to investigate the mechanisms of mGlu receptor-dependent LTD. However, recent experiments have argued for both a pre- and postsynaptic locus of expression of DHPG-induced LTD. In the present study we report that DHPG-induced LTD is not associated with changes in the sensitivity of CA1 neurons to bath applied AMPA. Furthermore, in contrast to homosynaptic LTD, DHPG-induced LTD is also not associated with changes in sensitivity to focally uncaged L-glutamate. These data do not support the notion that DHPG-induced LTD requires a modification of AMPA receptors, such as their internalisation, but are compatible with a presynaptic mechanism of expression.
Rammes
Gerhard
G
Max-Planck-Institute of Psychiatry, Kraepelinstrasse 2, 80804 Munich, Germany.
Palmer
Mary
M
Eder
Matthias
M
Dodt
Hans-Ulrich
HU
Zieglgänsberger
Walter
W
Collingridge
Graham L
GL
D000818:Animals; D004594:Electrophysiology; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D036881:Long-Term Synaptic Depression / Q000502:physiology*; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives* / Q000494:pharmacology; D009474:Neurons / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000502:physiology*; D013569:Synapses / Q000502:physiology*
D018094:Receptors, Metabotropic Glutamate; D018698:Glutamic Acid; D008734:Methoxyhydroxyphenylglycol; C010117:3,4-dihydroxyphenylglycol