The overall aim of the proposed research is to understand central nervous system (CNS) survival and regeneration. Reactive astrocytes characteristic of CNS injury or disease are postulated through poorly understood mechanisms to limit neuron regeneration in the adult mammalian CNS. By contrast, evidence accumulated in the last decade strongly supports the notion that astrocytes, the major non-neuronal CNS cell, may help promote neuron survival, the growth of neuron processes: axons and dendrites, and formation of neuron connections during development. Therefore by understanding astrocyte mediated process growth or neuron survival it may be possible to design therapeutic strategies that can promote regeneration and recovery in the diseased or damaged CNS and spinal cord. Three hypotheses will be examined: I: Astrocytes exposed to pathological insults support primary dendrite but limited axon growth. II: Astrocytes can support regeneration, but the extent varies with astrocyte subtype. III: Astrocytes can modulate neuron survival and apoptosis. These experiments will be performed in dissociated tissue culture and an organotypic culture system, that retains many in vivo characteristics absent in primary culture, using morphometry, immunohistochemical techniques, TUNEL labeling, computer assisted quantitative analysis, ELISA, quantitative Western blot analysis, DNA laddering, and antisense oligonucleotide strategies. In addition to the fundamental importance of the processes that result in neuron survival, axon and dendrite growth, an understanding of astrocyte mediated regeneration is important and may lead to novel strategies for intervention in acute neurological disorders including stroke, traumatic brain injury, and spinal cord injury and is essential for devising rational treatment to repair the damaged CNS.
