Synapse-specific mGluR1-dependent long-term potentiation in interneurones regulates mouse hippocampal inhibition.
Hippocampal CA1 inhibitory interneurones control the excitability and synchronization of pyramidal cells, and participate in hippocampal synaptic plasticity. Pairing theta-burst stimulation (TBS) with postsynaptic depolarization, we induced long-term potentiation (LTP) of putative single-fibre excitatory postsynaptic currents (EPSCs) in stratum oriens/alveus (O/A) interneurones of mouse hippocampal slices. LTP induction was absent in metabotropic glutamate receptor 1 (mGluR1) knockout mice, was correlated with the postsynaptic presence of mGluR1a, and required a postsynaptic Ca2+ rise. Changes in paired-pulse facilitation and coefficient of variation indicated that LTP expression involved presynaptic mechanisms. LTP was synapse specific, occurring selectively at synapses modulated by presynaptic group II, but not group III, mGluRs. Furthermore, the TBS protocol applied in O/A induced a long-term increase of polysynaptic inhibitory responses in CA1 pyramidal cells, that was absent in mGluR1 knockout mice. These results uncover the mechanisms of a novel form of interneurone synaptic plasticity that can adaptively regulate inhibition of hippocampal pyramidal cells.
Lapointe
Valérie
V
Département de physiologie, Centre de recherche en sciences neurologiques, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Qc, Canada H3C 3J7.
Morin
France
F
Ratté
Stéphanie
S
Croce
Ariane
A
Conquet
François
F
Lacaille
Jean-Claude
JC
D000818:Animals; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D007395:Interneurons / Q000187:drug effects / Q000502:physiology*; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000172:deficiency / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid