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mGluR1/5 subtype‐specific calcium signalling and induction of long‐term potentiation in rat hippocampal oriens/alveus interneurones
Author(s) -
Topolnik Lisa,
Azzi Mounia,
Morin France,
Kougioumoutzakis André,
Lacaille JeanClaude
Publication year - 2006
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2006.112896
Subject(s) - long term potentiation , neuroscience , metabotropic glutamate receptor , synaptic plasticity , interneuron , hippocampal formation , excitatory postsynaptic potential , neurotransmission , synapse , postsynaptic potential , ltp induction , biology , inhibitory postsynaptic potential , glutamate receptor , chemistry , receptor , biochemistry
Hippocampal inhibitory interneurones demonstrate pathway‐ and synapse‐specific rules of transmission and plasticity, which are key determinants of their role in controlling pyramidal cell excitability. Mechanisms underlying long‐term changes at interneurone excitatory synapses, despite their importance, remain largely unknown. We use two‐photon calcium imaging and whole‐cell recordings to determine the Ca 2+ signalling mechanisms linked specifically to group I metabotropic glutamate receptors (mGluR1α and mGluR5) and their role in hebbian long‐term potentiation (LTP) in oriens/alveus (O/A) interneurones. We demonstrate that mGluR1α activation elicits dendritic Ca 2+ signals resulting from Ca 2+ influx via transient receptor potential (TRP) channels and Ca 2+ release from intracellular stores. By contrast, mGluR5 activation produces dendritic Ca 2+ transients mediated exclusively by intracellular Ca 2+ release. Using Western blot analysis and immunocytochemistry, we show mGluR1α‐specific extracellular signal‐regulated kinase (ERK1/2) activation via Src in CA1 hippocampus and, in particular, in O/A interneurones. Moreover, we find that mGluR1α/TRP Ca 2+ signals in interneurone dendrites are dependent on activation of the Src/ERK cascade. Finally, this mGluR1α‐specific Ca 2+ signalling controls LTP at interneurone synapses since blocking either TRP channels or Src/ERK and intracellular Ca 2+ release prevents LTP induction. Thus, our findings uncover a novel molecular mechanism of interneurone‐specific Ca 2+ signalling, critical in regulating synaptic excitability in hippocampal networks.