Trophins as Mediators of Astrocyte Effects in the Aging and Regenerating Brain

Abstract

In their role as cells that provide multiple forms of support to the central nervous system (CNS), astrocytes are beginning to be appreciated as suppliers of critical survival and differentiation factors to neurons and other glia. Current work suggests that astrocytes may express these trophic factors throughout life, not only in the developing fetus, but also in the adult and aged individual. Moreover, studies on brain injury suggest that expression of astrocyte-derived factors is plastic and may be regulated by molecules elicited by injury, such as cytokines, hormones, and growth factors, as well as neurotransmitters. The hope is that as a result of these studies these regulatory molecules may be utilized to enhance astrocyte trophin function and thereby support the aging and injured brain. To examine these contentions, this chapter 1. Defines expression of growth factors by adult astrocytes 2. Considers the regulation of this expression by injury 3. Details effects of injury-induced molecules on growth factor expression and 4. Discusses the possible implications of alterations in astrocyte-derived trophic support on learning, memory, and the vulnerability of the CNS to aging and injury.