The effect of ethanol on cell fate determination of neural stem cells

Background: Recent studies have described the possible relevance of impaired neural stem cell (NSC) functions to the pathophysiology of psychiatric disorders, including alcoholism. However, relatively little is known about ethanol's effects on the determination of cell fate in NSCs. In this study, we investigated the effect of ethanol on neuronal and glial differentiation of NSCs. Methods: Under neuron-inductive culture conditions, NSCs were induced to differentiate and exposed to ethanol for 96 hr. Immunocytochemistry with cell- type-specific markers was performed (microtubule-associated protein 2 (MAP2) for neurons, glial fibrillary acidic protein (GFAP) for astrocytes and O4 for oligodendrocytes). The cells positive to MAP2, GFAP or O4 were counted, and the number of MAP2-positive cells was quantified by enzyme-linked immunosorbent assay (ELISA) following immuncistaining with anti-MAP2 (MAP2-ELISA). The alteration of MAP2, GFAP or myelin basic protein (MBP, a marker for oligodendrocytes) expression was evaluated by Western blot analysis. Results: Ethanol exposure increased astrocytic and oligodendrocytic differentiation with a statistically significant difference at 100mM, while 25 to 100 mM ethanol reduced neuronal differentiation without affecting the viability of NSCs. The enhanced expression of glial markers was revealed by Western blot analvsis for GFAP or MBP. Conclusions: Glial cells are known to increase in response to various kinds of insults to the central nervous system. It is possible that the increase of astrocytes and oligodendrocytes after ethanol exposure is a compensatory mechanism to repair the impaired neural network by promoting neurite outgrowth and increasing newly generated neurons.