ß-adrenergic signaling promotes morphological maturation of astrocytes in female mice
Astrocytes play essential roles in the developing nervous system, including supporting synapse function. These astrocyte support functions emerge coincident with brain maturation and may be tailored in a region-specific manner. For example, gray matter astrocytes have elaborate synapse-associated processes and are morphologically and molecularly distinct from white-matter astrocytes. This raises the question of whether there are unique environmental cues that promote gray matter astrocyte identity and synaptogenic function. We previously identified adrenergic receptors as preferentially enriched in developing gray versus white matter astrocytes, suggesting that noradrenergic signaling could be a cue that promotes the functional maturation of gray matter astrocytes. We first characterized noradrenergic projections during postnatal brain development in mouse and human, finding that process density was higher in the gray matter and increased concurrently with astrocyte maturation. RNA-sequencing revealed that astrocytes in both species expressed ? and ß adrenergic receptors. We found that stimulation of ß adrenergic receptors increased primary branching of rodent astrocytes in vitro. Conversely, astrocyte-conditional knockout of the ß1 adrenergic receptor reduced the size of gray matter astrocytes, and led to dysregulated sensorimotor integration in female mice. These studies suggest that adrenergic signaling to developing astrocytes impacts their morphology and has implications for adult behavior, particularly in female animals. More broadly, they demonstrate a mechanism through which environmental cues impact astrocyte development. Given the key roles of norepinephrine in brain states such as arousal, stress, and learning, these findings could prompt further inquiry into how developmental stressors impact astrocyte development and adult brain function. Overall design: 8 samples total consisting of 4 biological replicates per group of flow sorted astrocytes from cortical or subcortical tissue at P29