Spatio-Temporal Expression Patterns of Connexins 43 and 30 in Hippocampal Astrocytes During Postnatal Development.

Astrocytes are extensively interconnected via gap junction channels formed primarily by connexin 43 (Cx43) and connexin 30 (Cx30), two proteins that play central roles in intercellular signaling and homeostatic regulation in the brain. Although the functional properties of these connexins have been widely investigated, their spatial organization within astrocytes and its evolution during postnatal development remain poorly characterized. Here, we combined confocal and stimulated emission depletion (STED) super-resolution microscopy to examine the expression, distribution and colocalization of Cx43 and Cx30 immunoreactive puncta in hippocampal astrocytes from postnatal day 15 to adulthood. Quantitative analyses revealed a progressive increase in the number of both Cx43 and Cx30 puncta during development, whereas puncta size remained largely unchanged. Although connexin puncta appeared more distally distributed in mature astrocytes, this shift was fully accounted for by the growth of astrocytes during development. In addition, colocalization between Cx43 and Cx30 increased during maturation, reaching a stable level after postnatal day 30. Finally, STED super-resolution imaging revealed a diversity of connexin arrangements, including isolated puncta as well as complex assemblies composed of multiple neighboring connexin clusters. Together, these findings provide a quantitative characterization of the developmental remodeling of astroglial connexins and identify structural features that may contribute to the maturation of astrocytic networks.