Astrocytes in neurodegenerative diseases (I): function and molecular description.

INTRODUCTION Astrocytes have been considered mere supporting cells in the CNS. However, we now know that astrocytes are actively involved in many of the functions of the CNS and may play an important role in neurodegenerative diseases. DEVELOPMENT This article reviews the roles astrocytes play in CNS development and plasticity; control of synaptic transmission; regulation of blood flow, energy, and metabolism; formation of the blood-brain barrier; regulation of the circadian rhythms, lipid metabolism and secretion of lipoproteins; and in neurogenesis. Astrocyte markers and the functions of astrogliosis are also described. CONCLUSION Astrocytes play an active role in the CNS. A good knowledge of astrocytes is essential to understanding the mechanisms of neurodegenerative diseases.