Activity-dependent compartmentalized regulation of dendritic Ca2+ signaling in hippocampal interneurons.
Activity-dependent regulation of synaptic inputs in neurons is controlled by highly compartmentalized and dynamic dendritic calcium signaling. Among multiple Ca(2+) mechanisms operating in neuronal dendrites, voltage-sensitive Ca(2+) channels (VSCCs) represent a major source of Ca(2+) influx; however, their use-dependent implication, regulation, and function in different types of central neurons remain widely unknown. Using two-photon microscopy to probe Ca(2+) signaling in dendrites of hippocampal oriens/alveus interneurons, we found that intense synaptic activity or local activation of mGluR5 induced long-lasting potentiation of action potential evoked Ca(2+) transients. This potentiation of dendritic Ca(2+) signaling required mGluR5-induced intracellular Ca(2+) release and PKC activation and was expressed as a selective compartmentalized potentiation of L-type VSCCs. Thus, in addition to mGluR1a-dependent synaptic plasticity, hippocampal interneurons in the feedback inhibitory circuit demonstrate a novel form of mGluR5-induced dendritic plasticity. Given an implication of L-type VSCCs in the induction of Hebbian LTP at interneuron excitatory synapses, their activity-dependent regulation may represent a powerful mechanism for regulating synaptic plasticity.
Département de Biochimie et de Microbiologie, Faculté des Sciences et de Génie, Université Laval, Québec City, Québec, Canada. Lisa.Topolnik@crulrg.ulaval.ca
Lisa
L
Topolnik
Simon
S
Chamberland
Joe-Guillaume
JG
Pelletier
Israeli
I
Ran
Jean-Claude
JC
Lacaille
D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D003712:Dendrites / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology* / Q000502:physiology*; D007395:Interneurons / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D055366:Synaptic Potentials / Q000502:physiology*