The long-term goal of this proposal is to identify molecular biological (gene) products that are associated with neuronal degeneration, and to discover new neuro-protective agents that can be used to prevent neuronal degeneration. This study is essential because neuronal losses are known to occur during aging; and sometimes they can lead to neurological disorders such as Alzheimer's disease. Mechanistic studies are difficult to perform in central nervous system in vivo, because it contains hetero- geneous cell populations. Differentiated murine neuroblastoma (NB) cells (adrenergic and cholinergic) spontaneously degenerate, and this process can be accelerated by neurotoxins such as glutamate and 6-hydroxydopamine (6-OHDA). Therefore, they can be useful models to study differentiation and degeneration of specific types of neurons.
The Specific Aims of this proposal are the following: a) to investigate the involvement of cell signaling pathways during differentiation of NB cells; b) to investigate the changes in cell signaling pathways during spontaneous and chemically-induced degeneration of differentiated adrenergic and cholinergic NB cells; c) to investigate the effect of vitamin E and ganglioside GM1 in prevention of spontaneous and chemically-induced degeneration of differentiated NB cells. Adrenergic clone NBA2(l), and cholinergic clone NBE-, will be used. Adenosine 3', 5'-cyclic monophosphate (cAMP) stimulating agents will be used to induce differentiation in the presence and absence of serum. 6-hydroxydopamine and glutamate will be used to induce rapid degeneration in differentiated NB cells. Alterations in signal transduction mechanisms represented by cAMP and diacylglycerol pathways will be determined. The parameters to be assayed include adenylate response to neurotransmitters, cAMP level, levels of protein kinase A (PKA) and PKC, and PKA- and PKC-dependent phosphorylation of proteins. The effects of vitamin E and ganglioside GM1 in preventing spontaneous and 6-OHDA- and glutamate-induced degeneration of differentiated adrenergic and cholinergic NB cells will be evaluated,using the same parameters. Future studies will focus on identification and characterization of gene products which are associated with neuronal degeneration and discovery of new neuroprotective agents.
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