Cell Journal (Jan 2009)
Calcium Signaling Pathways Involved in Long-Term Potentiation at Excitatory Synapses on Parvalbumin Positive Fast-Spiking GABAergic Neurons in the Mouse Visual Cortex
Abstract
Objective: Recently, we reported the presence of metabotropic glutamate receptor type 5(mGluR-5) dependent long-term potentiation (LTP) at excitatory synapses on fast-spikingGABAergic (FS-GABA) cells in the visual cortex. In this study, we report a Ca2+ signalingpathway involved in this LTP type.Materials and Methods: Brain slices from GAD67-GFP knock-in mice were used. Usingwhole-cell patch-clamp recording followed by immunohistochemical staining on parvalbumin-positive (PV+) FS-GABA cells, we studied the Ca2+ signaling pathway involved inexcitatory LTP of certain visual cortical interneuron subtypes.Results: U-73122- a phospolipas c (PLC) inhibitor (10 μM), inositol triphosphate (IP3) inhibitorssuch as 2-APB (3 μM) and heparin (10 IU/ml), and CPA- the internally stored Ca2+release inhibitor- (5 μM) blocked the mGluR5 signaling pathway to induce LTP at excitatorysynapses on PV+ fast-spiking cells in the visual cortex. However, application of the vehiclesalone had no effect.Conclusion: Our results indicate that mGluR-5 at FS-GABA neurons activate PLC andIP3 production. This leads to Ca2+ release, promotes LTP induction, and its maintenance issupported by internal Ca2+ stores. Considering the key role of PV+ FS inhibitory neurons inthe visual cortex circuits, we suggest that the metabotropic glutamate receptor-dependentLTP of excitatory synapses to FS cells plays a crucial role in the visual cortex plasticity.
