Motor learning and dopamine-dependent striatal synaptic plasticity are controlled by astrocytic MEGF10.

Dopamine regulates motor learning by modulating striatal synaptic plasticity in medium spiny neurons (MSNs). Despite its well-established role in synaptic plasticity, dopamine's involvement in glia-mediated synapse remodeling remains unclear. Here, we demonstrate that the astrocytic phagocytic receptor MEGF10 (Multiple Epidermal Growth Factor-like Domains Protein 10), but not MERTK (MER Proto-Oncogene, Tyrosine Kinase), is required for the elimination of corticostriatal excitatory synapses on MSNs during motor learning. Deletion of astrocytic Megf10 impaired long-term potentiation and depression (LTP and LTD), and reduced learning-induced increases in synaptic strength. Notably, chemogenetic activation of corticostriatal transmission or dopamine release from the substantia nigra pars compacta (SNc) selectively enhanced astrocytic synapse elimination. Furthermore, elevated dopamine and motor learning differentially regulated postsynaptic elimination in MSNs depending on dopamine receptor subtype, leading to MEGF10-dependent changes in synaptic remodeling and quantal properties. These findings identify astrocytic MEGF10 as a key mediator of dopamine- and activity-dependent synapse remodeling in the striatum.