The influence of astrocytes on the development,regeneration and reconstruction of the nigrostriatal dopamine system

Abstract

Over the past few decades astrocytes have emerged from being considered simple packing tissue in the brain to become major players in the development, survival and functioning of central nervous system (CNS) neurons. As the influence that astrocytes (and the various molecules they produce) have on the development of CNS neurons becomes more evident, it will be important to consider how this information can be exploited to bring about better protection, recovery and/or regeneration of circuits which are destroyed in the adult CNS due to trauma or com-mon neurodegenerative episodes. Although the characterisation of astrocytic responses to brain injuries, neurodegenerative disease, and cell transplantation are becoming more common, we still known little about how astrocytes influence the (re)growth or reconstruction of neural cir-cuitry after the development period is ended, or indeed what is the overall impact of an astrocytic presence on the growth of neurons in the adult CNS. With the major hurdle of recognition of the importance astrocytes in the function and recovery of the adult CNS now cleared, a new chapter in the development of powerful new treatments for CNS disorders and injuries is now open. The following is a brief review of what we know about how astrocytes influence the growth and connectivity of the nigrostriatal circuit during development, and how these cells may affect efforts to reform this circuit after its destruction/degeneration in the adult CNS (as commonly happens in Parkinsons disease). As we obtain more information on the specific influence of these cells in various developmental, traumatic and disease events we can expect to find better ways toward combating major disorders of the human CNS.