The Effects of Activity of Astrocytes on Neuron Dendritic Filopodia Motility

The motile behavior of dendritic filopodia is a way by which neurons explore extracellular environment and could serve to connect dendrites with axons forming early synapses. It is unclear whether activity of astrocyte affects the motility of neuronal filopodia. To explore this possibility, astrocytes were transfected with channelrhodopsin-2 in a neuron-astrocyte mix culture model first. Expressing on cytoplasic membrane, channelrhodopsin-2 was activated by pulses of blue light and caused activation of astrocyte, in which different dynamic patterns of Ca(2+) current were shown after the stimulation. Activated astrocytes have an inhibitory effect on filopodia motility similar to extracellularly administrated ATP and glutamate. This indicates that activated astrocytes could probably inhibit dendritic filopodia motility through releasing ATP or glutamate. A method of selectively activating astrocytes in the mix culture of neuron and astrocyte was established, which provides a novel way for studying astrocytic signal regulation of neuronal development.