Although it is generally conceded that ethanol can be toxic to neurons, it is not known by what mechanisms this toxicity is mediated. The sensitive, reciprocal interactions between calcium and neurotrophic factors, and the importance of each of these with respect to neuronal survival, led the applicants to investigate whether ethanol might produce toxicity through effects on these molecules. Based on a wealth of biochemical studies of ethanol effects on calcium, on preliminary results that ethanol can alter both resting and potassium depolarization-stimulated intracellular calcium, and on more established effects on brain neurotrophic activity, a more detailed investigation is proposed of ethanol effects on intracellular calcium regulation. It is hypothesized that: (1) ethanol may act to disrupt normal calcium homeostasis (resting and/or stimulated); (2) this disruption may (like other treatments that alter [Ca+2]i) affect the expression of neurotrophic factor or receptor genes; (3) ethanol may interfere with the ability of neurotrophic factors to modulate Ca+2i regulation; and (4) neurotrophic factors may be able to offset the effects of ethanol on Ca+2i regulation. These ideas will be tested by measuring Ca+2i in living alcohol- treated neurons, and in situ hybridized neurotrophic factor and receptor mRNAs. Assessment will follow both acute and chronic ethanol treatments, before and after depolarization challenge, in the presence or absence of neurotrophic factors, with a range of ethanol doses, in 3 distinct in vitro systems. The use of 3 culture models offers comparison of different neuronal types which demonstrate different neurotrophic response characteristics, as well as a sequential approximation of in vivo organization. If ethanol is found to disrupt normal Ca+2i metabolism in a manner that is ameliorated by neurotrophic factors, the investigators will test the ability of prolonged neurotrophic factor treatment to reduce the neuropathological consequences of chronic ethanol treatment.
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