Astrocytogenic bidirectional plasticity at spinal nociceptive synapses regulates acute nociceptive processing.

Astrocytes are key players in chronic pain, driving maladaptive changes in neuronal circuits. Yet, their influence on acute nociception-the body's first line of defense against harmful stimuli-remains poorly understood. Using chemogenetic tools to mimic endogenous astrocytic G-protein-coupled receptor-mediated signaling, we reveal that astrocytes induce bidirectional plasticity at nociceptive synapses in the dorsal horn. Depending on the state of these synapses and on concurrent afferent input, astrocytes can either suppress nociceptive transmission by enhancing glycinergic tone, or amplify synaptic strength at C-fiber synapses through interactions with microglia. This dynamic regulation expands the acute computational capacity of spinal nociceptive networks, enabling precise and adaptive responses to noxious stimuli on a short time scale. Our findings challenge the traditional view of astrocytes as passive supporters of neuronal activity and establish them as active regulators of spinal plasticity, integrating sensory information and network states to shape pain perception in real time.