GAP-JUNCTIONS IN BRAIN GLIAL-CELLS

In the brain, in vivo as in vitro, glial cells represent the main cell population which communicates through intercellular channels forming gap junctions. These cells, and specially the astrocytes, also express a large variety of ionic channels and membrane receptors. The combina tion of biochemical, immunological and electrophysiological techniques has allowed to determine that connexin 32 is present in oligodendrocy tes while connexin 43 is the major junctional protein in astrocytes. T he conductance and permeability of gap junctions in astrocytes are con trolled by endogenous compounds released from izeurorzs or endothelial cells. This suggests that gap junctional communication in astrocyte n etworks exhibits some degree of plasticity and are under the control o f other brain cell populations. The expression of connexins and the re gulation of junctional permeability in astrocytes may contribute to se veral glial functions such as intercellular calcium signalling and met abolic trafficking within the brain.