Glial cells undergo rapid changes following acute chemogenetic manipulation of a subpopulation of layer 5 projection neurons

Communication between neurons and glial cells are crucial to establish and maintain brain function. Some of these interactions are activity-dependent, yet it remains unexplored how acute changes in neuronal activity affect neuron-to-glial dynamics.Here, we used excitatory and inhibitory designer receptors exclusively activated by designer drugs (DREADD) based chemogenetic methods to study the effects of acute manipulations of a subpopulation of layer 5 cortical projection and dentate gyrus neurons in adult (Rbp4Cre) mouse brain after 90 minutes. We validated changes in activity with in vitro patch clamp recording and with immediate early gene expression. We demonstrated that acute chemogenetic neuronal activation leads to microglia hyperactivation, reactive astrogliosis, increased parvalbumin expression in interneurons and lower synaptic density. Whereas acute chemogenetic ‘silencing’ of the same neurons reduce microglia activity, inhibit astrocytic reactivity, increase synaptic density, but has no effect on parvalbumin expression. Acute changes in neuronal activity elicit rapid effects on the interactions between glial cells, glutamatergic and GABAergic neuronal networks. Collectively, these findings provide insights into the widespread activity-dependent communication between neuronal networks and glial cells.