MicroRNA-Mediated Inhibition of Excitatory Postsynaptic Currents in Mouse Hippocampal Slices

Source: Thalhammer, A., et al. Combining Optogenetics with Artificial microRNAs to Characterize the Effects of Gene Knockdown on Presynaptic Function within Intact Neuronal Circuits. J. Vis. Exp. (2018) This video demonstrates microRNA-mediated inhibition of excitatory synaptic currents in mouse hippocampal brain slices. The CA3 neurons were infected with a recombinant viral vector harboring a construct for expressing a fluorescent reporter, a light-activated membrane channel, and a microRNA that downregulates the expression of voltage-gated calcium channels. Upon placing a slice in a recording chamber and patching a CA1 neuron with a recording pipette, light pulses were used to stimulate the light-activated channel, resulting in an ion influx and generating an action potential. The absence of voltage-gated calcium channels in CA3 neurons inhibits neurotransmitter release, causing inhibition of excitatory postsynaptic currents in the synaptically-connected CA1 neurons.