Astrocytic functions and physiological reactions to injury: the potential to induce and/or exacerbate neuronal dysfunction--a forum position paper.

This forum highlights the wide diversity of astrocytic functions which maintain CNS homeostasis, well beyond the originally proposed passive cytoskeletal support role for these cells. Astrocytic potential in modulating damage and repair is also reflected in this forum. While astrocytes may potentially play a primary role in epilepsy, and in neurodegenerative disorders such as Huntington's diseases, HIV, and demyelination, one needs to keep in mind that to a large extent evidence supporting involvement of astrocytes in these diseases is derived from in vitro studies. Observations on regional heterogeneity and functional specialization of astrocytes also suggest that astrocytes have adapted to perform functions specific to their respective residence site. Therefore, it is necessary to identify potentially damaging consequences of astrocytic functions in vivo, although these analyses will be undoubtedly extremely complex. Expanded investigations on astrocytic involvement in neurotoxicity and neurodegeneration is clearly warranted, and as new experimental tools are developed it is likely that further strides will be made in our understanding of astrocyte functions, both in health and disease.