Prolonged alcohol abuse causes brain damage, but the mechanisms remain uncertain. From studies with adult rats in vivo and rat brain slice cultures, we know that chronic binge alcohol (ethanol) exposure and withdrawal (""""""""alcoholic"""""""" levels, 70-120 mM) cause hippocampal/cortical neurodegeneration that (a) is not typically excitotoxic;(b) entails brain edema (diuretics prevent the edema and neurodamage);(c) involves oxidative stress (antioxidants neuroprotect);and (d) requires phospholipase A2 (PLA2) activation, which mobilizes (JO-6 arachidonic acid (AA), a free radical source (PLA2 inhibitors reduce neurodamage). Notably, u)-3 fatty acid docosahexaenoic acid (DHA) suppresses AA release and provides neuroprotection. Meanwhile, research by H.Y. Kim, NIAAA intramural investigator and DHA/alcohol research pioneer, indicates a related """"""""lipid-based"""""""" mechanism of alcohol-induced apoptotic neurodamage involving depletion of DHA-containing phosphatidylserine (PS) and reduced pro-survival signaling that are also prevented by DHA supplementation. With Dr. Kim's collaboration, this U01 application explores functional connections between these two neurodegenerative mechanisms, and how DHA protection is realized. We propose to research three aims, posed here as questions, using adult-age (as opposed to usual adolescent) rat organotypic hippocampal/ entorhinal cortical slice cultures chronically exposed to binge alcohol/ withdrawal;techniques include biolistic transfection, antisense oligos and HPLC/MS analysis.
Aim I : Are alcohol-induced reductions of membrane PS, DHA content and downstream pro-survival kinase (Akt, raf-1) activities causative events in subsequent neurodegeneration/apoptosis? Aim 2: Are alcohol-induced edema, PLA2 activation, AA mobilization and oxidative stress leading to neurodegeneration coupled to alcohol-induced changes in membrane aminophospholipids and survival kinase activities? and Aim 3: Does DHA-supplemented neuroprotection during binge alcohol entail DHA incorporation into/ potentiation of membrane PS, increased pro-survival signaling, reduced PLA2 activity and diminished AA release/oxidative stress? The lipid analyses in Aims 1 &3 are accomplished in Dr. Kim's NIAAA laboratory;all other research is at Loyola University.
This U01 collaborative study of chronic binge alcohol's potential neuroinflammatory, lipid-based mechanisms of brain toxicity and DHA neuroprotection holds the promise of yielding nutritional and other insights that can be therapeutically valuable in reducing neurodegeneration and brain dysfunction in alcohol abuse and withdrawal.
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