Ethanol in Clinically Relevant Concentrations Enhances Expression of Oligodendroglial Differentiation but Has No Effect on Astrocytic Differentiation or DNA Synthesis in Primary Cultures

Abstract

Primary cultures of cerebral glia derived from newborn rat brain were utilized to evaluate the effects of ethanol on DNA synthesis and cellular differentiation. Glutamine synthetase was employed as a marker for astrocytic differentiation and 2′,3′-cyclic nucleotide 3′-phosphohydrolase (CNP), for oligodendroglial differentiation. Concentrations of ethanol of 17–86 mM, i.e., a concentration range comparable to that observed in humans, were utilized. No effect of ethanol on DNA synthesis was observed, despite the use of synchronized cultures. Similarly, no effect of ethanol on the developmental increase of glutamine synthetase activity was seen, despite the use of astrocytes purified by the selective detachment technique and a prolonged duration of exposure to ethanol (17 days). In contrast, however, a striking enhancement of CNP activity was demonstrable in both mixed glial cultures and in oligodendroglia purified by the selective detachment technique. In the latter cells, the stimulatory effect of ethanol was evident within 9 days of exposure, and after 17 days of exposure, ethanol-treated cells exhibited a two-fold higher CNP activity than did control cells. This peak effect was observed at an ethanol concentration of only 17 mM. Thus, these data indicate that (1) clinically relevant concentrations of ethanol have no effect on either DNA synthesis or on at least one expression of astrocytic differentiation in glial primary cultures, but (2) these concentrations exert a striking enhancement of CNP activity, a marker of oligodendroglial differentiation. The findings have implications both for the effects of ethanol on the developing nervous system and the regulation of oligodendroglial differentiation.

Effects of Ethanol Exposure on Myelination and Axon Numbers in the L2 Dorsal Root of the Neonatal Rat

“…In addition, Kennedy and Mukerji [6] reported a decrease in glutamine synthetase (a marker of astrocyte differentiation) in cultures derived from cerebral cortex of newborn mice. However, Bass and Volpe [7], using primary cultures of cerebral glia derived from newborn rat brain, observed an ethanol-in duced increase in 2',3'-cyclic nucleotide 3'-phosphohydrolase (a marker for oligodendroglial differentiation) and no change in glutamine synthetase. Furthermore, some investigators have measured significant reductions in the quantity of brain myelin fractions [8][9][10] while others have reported near-normal to increased myelin protein content in offspring exposed to ethanol during gestation [11][12][13][14], Differences in ethanol exposure peri ods and techniques have been suggested as possible rea sons for these discrepancies [10].…”

Effects of Ethanol on Glial Cell Proliferation: Relevance to the Fetal Alcohol Syndrome

“…These observations w ere con rmed in a subsequent study, w here exposure or rat m ixed glial prim ary cu ltures to ethanol ( 17,43, and 86 mM ) for four days had no eÚ ect on DNA synthesis [ 22] . On the other hand, Kennedy and M ukerji [ 23] reported that astrocytes from newborn mice cultured from postnatal day 6 to 17 in the presence of ethanol ( 11,22, and 45 mM ) displayed a decrease content of DN A com pared to untreated controls ; the eÚ ect w as quit e sm all and w as seen only at the high est alcohol concentration ( 45 m M ) . Yet, in another study, no eÚ ects of ethanol ( 10-60 mM ) w ere observed follow ing a four day exposure of fetal rat astrocytes [ 24] .…”

“…Sim ilarly, 100 or 200 mM ethanol w ere found to in hibit [ 3H ]thym idine in corporation of rat astrocytes follow ing a 18-24 hr exposure [ 28,29] though no eÚ ects were seen in another study [ 30] . The proliferation of astroglia from adult human cerebrum, m easured by 5-bromo-2'deoxyuridine-5'-monophosphate in corporation into DN A, w as also inhibit ed by ethanol ( 22,45, and 109 mM ) [ 31] .…”

“…M ore than a decade ago, Davies and V ernadakis [ 21] exam ined the eÚ ect of exposure of glial cells, prepared from 15-day-old chick embryos, to ethanol ( 22,109,217, and 434 mM ) for four days ( day 6 to 10 in culture) . The tw o higher concentrations of ethanol caused a 20-40% reduction in DNA content, while at the lower concentrations cell grow th did not di Ú er from control.…”

Effects of ethanol on neuroblastoma cells in culture: Role of gangliosides in neuritogenesis and substrate adhesion

“…In adult humans blood ethanol levels of 10 mM (less than 0.1%) are associated with disturbances of mentation and coordination. With blood ethanol levels of 20 mM ataxia is observed, 70 mM with stupor and 90 mM and higher with coma and possibly death (Bass and Volpe, 1988). Of course, habituated, chronic alcoholics exhibit higher thresholds (Urso et al, 1981).…”