CONTROL OF GAP-JUNCTIONAL COMMUNICATION IN ASTROCYTIC NETWORKS

Astrocytes, which constitute the most abundant cell type in mammalian brain, are extensively coupled to one another through gap junctions co mposed mainly of connexin43. In regions exhibiting high levels of conn exin43 expression,tens of astrocytes are labeled following single-cell intracellular injection. Importantly, both the expression and the per meability of gap junctions are tightly regulated. Such long- and short -term regulations indicate that astrocytic networks might be subject t o remodeling and to some plasticity. Since evidence for neuro-glial in teraction exists, the degree of coupling between astrocytes could part icipate to set the tone of neuronal activity and to determine the sphe re of influenced neurons. Research in this area is still at its early stages and significant progress requires a transition from the underst anding of basic properties to the study of function.