Chronic ethanol promotes the neuronal differentiation of NG108-15 cells independently of toxin-sensitive G-proteins

The ability of ethanol to promote neuronal differentiation of NG108-15 mouse neuroblastoma x rat glioma hybrid cells was investigated using morphological, biochemical and electrophysiological techniques. Ethanol concentration-(10-200 mM) and time - (1 h-3 days) dependently reduced cell proliferation, but increased acetylcholinesterase (AChE) activity and cell protein content. Chronic ethanol (200 mM) also time-dependently increased voltage-sensitive Ca²⁺ currents in the cells. Similar effects were obtained with chronic treatment of the cells with the standard differentiating agents sodium butyrate or forskolin. Chronic treatment of NG108-15 cells with primary alcohols (0.1-200 mM) of varying chain length all reduced cell proliferation and increased cell protein content and AChE activity with the potency order butanol > propanol > ethanol > methanol. Chronic treatment of NG108-15 cells with cholera toxin (50 ng ml^-1) or pertussis toxin (50 ng ml^-1) did not induce differentiation of the cells, nor did it modify the effects of 50 or 200 mM ethanol on cell proliferation, AChE activity or cellular protein content. Chronic cholera toxin did however abolish agonist-stimulated adenylyl cyclase activity in the cells, whereas pertussis toxin abolished receptor-mediated inhibition of adenylyl cyclase activity. Furthermore, inhibitors of protein kinase C (GF 109203X, 5 μM), protein kinase A (11-89, 10 μM) or Ca²⁺/calmodulin-dependent protein kinase II (KN-62,3 μM) all failed to modify the effects of 200 mM ethanol on cell proliferation, AChE activity and cellular protein content. These experiments indicate that chronic ethanol is able to promote neuronal differentiation of NG108-15 cells independently of toxin-sensitive G-proteins and some protein kinases.