Impact of single-site axonal GABAergic synaptic events on cerebellar interneuron activity.

摘要: Axonal ionotropic receptors are present in a variety of neuronal types, and their function has largely been associated with the modulation axonal activity synaptic release. It is usually assumed that activation GABAARs comes from spillover, but cerebellar molecular layer interneurons (MLIs) GABA source different: these cells, release activates presynaptic GABAA autoreceptors (autoRs) together postsynaptic targets, producing an autoR-mediated event. The frequency presynaptic, miniature currents twice somatodendritic counterparts, suggesting responses have important effect on interneuron activity. Here, we used local Ca2+ photolysis MLI axons juvenile rats to evoke individual varicosities study autoRs single sites. Our data show single-site autoR conductances similar dendritic conductances. In conditions high [Cl−]i, range 1 5 nS; this corresponds ∼30–150 channels per varicosity, value close number densities. Voltage produced by amplified Nav-dependent mechanism propagate along axon length constant 91 µm. Immunolabeling determination synapse location shows average, one third synapses produce signals large enough reach initial segment. Finally, leads increase excitability thus conveys strong feedback signal contributes spiking