Аннотация:Orchestrated activity of different cell types and their interactions within the brain active milieu provide the cellular basis for brain functions. Locomotion triggers a coordinated response of both neurons and astrocytes in various brain regions. Here we performed calcium (Ca2+) imaging of these two cell types in the somatosensory cortex in head-fixed mice moving on the airlifted platform. Ca2+ activity in astrocytes significantly increased during locomotion from a low baseline level during animal quiescence. Ca2+ signals first appeared in the distal processes and then propagated to astrocytic somata. In somata, Ca2+ concentration ([Ca2+]i) elevations became significantly larger and exhibited oscillatory behaviour. Hence, astrocytic soma operates as both integrator and amplifier of Ca2+ signal. In contrast to astrocytes, pronounced Ca2+ activity was detected in neurons in quiescent periods, and it further increased during locomotion. Neuronal [Ca2+]i rose almost immediately following the onset of locomotion, whereas astrocytic Ca2+ signals lagged by several seconds. Such a long lag suggests that astrocytic [Ca2+]i elevations are unlikely to be triggered by the activity of synapses among local neurons. Next, we compared Ca2+ responses to pairs of consecutive episodes of locomotion (paired-run ratio). Neurons reliably responded to each episode, whereas [Ca2+]i elevations in astrocytes were significantly diminished in response to the second locomotion. This refractory period in astrocytes may arise from distinct mechanisms underlying Ca2+ signal generation. In neurons, the bulk of Ca2+ enters through the Ca2+ channels in the plasma membrane allowing for steady-level Ca2+ elevations in repetitive runs. Astrocytic Ca2+ responses originate from the intracellular stores, the depletion of which affects subsequent Ca2+ signals. Functionally, neuronal Ca2+ response is primary and reflects sensory input processed by neurons. Astrocytic Ca2+ dynamics is secondary and likely to participate in regulation of metabolic and homeostatic support of intercellular communication and plasticity within the brain active milieu.