Ethanol exerts different effects on myelin basic protein and 2',3'-cyclic nucleotide 3'-phosphodiesterase expression in differentiating CG-4 oligodendrocytes.

Evidence suggests that abnormal myelination is one factor contributing to the neuoropathology associated with fetal alcohol syndrome. We investigated the potential teratogenic effects of ethanol (EtOH) on myelin formation by determining its effects on the developmentally regulated increased expression of myelin basic protein (MBP) and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) in differentiating CG-4 oligodendrocytes (OLGs). By using CG-4 OLGs in vitro we identified processes altered by ethanol actions exerted directly on OLGs. During the first 8 days of development, EtOH decreased the expression of the major structural 18.5 and 14 kDa MBP isoforms by at least 40% at 4 days of development. EtOH concentrations between 25 and 75 mM inhibited MBP expression in a dose-dependent manner. Adding or withdrawing EtOH on specific days of differentiation reversibly modulated the expression of MBP, and the degree of inhibition was directly related to the length of ethanol exposure. As little as two consecutive days of EtOH exposure either early or late during development caused at least a 20% inhibition, however, no short critical time window of EtOH vulnerability for the inhibition was observed. The ethanol effect was selective for MBP expression, as EtOH did not alter the developmentally-regulated increased expression of CNP isozymes or enzyme activity. The results indicate that one factor contributing to the development of fetal alcohol syndrome may be defective myelination resulting from delayed and decreased MBP expression.

Effects of transient ethanol exposure on the incorporation of [(3)H]ethanolamine into plasmalogen in the differentiating CG-4 oligodendrocyte cell line.

We investigated the potential teratogenic effects of ethanol (EtOH) on myelination by monitoring its effects on the labeling of the myelin-typical lipid, ethanolamine plasmalogen (EPl), in the CG-4 cell line of differentiating oligodendrocytes (OLGs). On 5 different days during the first 8 days of OLG development, cells were labeled for 24 hr with [(3)H]ethanolamine to label EPl and diacyl-ethanolamine phosphoglycerols (diacyl-EPG), and the amount of labeled lipid expressed on each day was determined in the presence and absence of 25-120 mM EtOH. At early stages of development, a lower amount of [(3)H]EPl per cell was found in cells exposed to EtOH. The ratio of [(3)H]EPl to [(3)H]diacyl-EPG in cells exposed to 25, 50, or 120 mM EtOH was decreased by 50% after 4 days of differentiation compared with that in control cells. By adding or withdrawing EtOH at specific days of differentiation, we showed that EtOH inhibited the increased labeling of EPl if it was present for the first 48 hr of differentiation, and subsequent withdrawal failed to relieve the inhibition. Addition of EtOH anytime after the first day of differentiation did not inhibit the increased labeling of EPl. The results show that the increased labeling of EPl in differentiating OLGs resulted from an EtOH-sensitive, developmentally programmed, transient process active only during the first 2 days of differentiation.

Temporal and quantitative expression of the myelin-associated lipids, ethanolamine plasmalogen, galactocerebroside, and sulfatide, in the differentiating CG-4 glial cell line.

We determined the expression of three myelin-typical lipids in the continuous CG-4 glial cell line of oligodendrocyte progenitor cells, as the cells differentiated into oligodendrocytes. On 6 different days during the first 9 days of oligodendrocyte development, cells were labeled for 24 h with [3H]ethanolamine to label ethanolamine plasmalogens or with [3H]galactose to label the galactocerebroside and sulfogalactocerebroside; and the amount of labeled lipid expressed on each day was determined. Each labeled lipid was expressed with its own specific time course and in a defined amount on each day of differentiation. Increased labeling of plasmalogens and sulfogalactocerebroside started at early developmental stages, and increased labeling of galactocerebroside started at later stages. The results indicate that the differentiating CG-4 cell line provides a valuable system to investigate factors affecting the early time course of myelin-lipid expression and the amounts expressed.

The effects of chronic ethanol consumption on the formation of phosphatidylethanolamine molecular species and their appearance at the plasma membrane.

The purpose of our study was to determine whether chronic ethanol consumption affected membrane assembly by altering the formation of specific molecular species of phosphatidylethanolamine (PE) and their subsequent incorporation into the plasma membrane (PM). We investigated the effects on the PE species made by the two major pathways in hepatocytes: (1) from CDP-ethanolamine in the endoplasmic reticulum, and (2) by the decarboxylation of phosphatidylserine (PS) in the mitochondria. Ethanol consumption exerted significant effects on the formation of ethanolamine-derived PE species and affected mainly two species, the 16:0/22:6 and 18:0/20:4 species. In cultured hepatocytes from ethanol-fed rats labeled with [3H]ethanolamine for 0.25 to 4 hr, the amount of the [3H]16:0/22:6 PE species was decreased compared with that in control cells, whereas the amount of [3H]18:0/20:4 species was increased. The amount of the [3H]16:0/22:6 PE species on the cell surface was also decreased in hepatocytes from ethanol-fed rats, whereas the amount of [3H]18:0/20:4 species was increased. In contrast, the profile of [3H]PE species formed in cells treated with [3H]serine exhibited minor alterations, and the profile of the serine-derived [3H]PE species on the cells surface was not altered after 4 hr of labeling. The changes in ethanolamine-derived species were apparently caused by time-dependent alterations in the metabolic processes, because the presence of 110 mM ethanol in the culture media did not affect the profiles of [3H]PE species in cells from control or ethanol-fed rats and was not required to sustain the altered profiles. The results indicate that the synthesis of specific PE molecular species and their appearance on the PM may occur by compartmentalized processes which are distinguishable by different sensitivities to ethanol consumption. The results indicate that ethanol consumption may contribute alcoholic hepatic injury by interfering with the metabolism of specific PE molecular species and their assembly into the PM.

[Effect of polynucleotide adsorption on characteristics of a planar phosphatidylcholine bilayer membrane]. / Vliianie adsorbtsii polinukleotidov na kharakteristiki ploskoi bisloinoi fosfatidilkholinovoi membrany.

Interaction of DNA with planar bilayer phosphatidylcholine membrane in the presence of CaCl2 increases electric conductance of the membrane several times as a result of the formation of DNA-membrane complex. The same effect was observed in the cases of ribosomal RNA and synthetic homopolymers polyA, polyU and polyA X polyU double helix.

[Interaction of poly A with phospholipid membranes using IR-spectroscopy]. / Izuchenie vzaimodeistviia poliA s fosfolipidnymi membranami metodom IK-spektroskopii.

IR-spectra of poly-A phosphatidylcholine complexes in D2O were studied. It has been shown that in the absence of Mg2+ the spectrum was a superposition of spectra of poly-A and phosphatidylcholine. Introduction of MgCl2 to the concentration of 0.03 M led to the dramatic decrease of absorbance at 1629 cm-1 characteristic of backbone vibration of adenine. Further increase of the concentration of MgCl2 up to 0.08 M resulted in the additional absorbance maximum at 1627 cm-1. Under a variety of temperatures the position of the maximum did not change. It was assumed that on adding magnesium ions to the "poly-A-lipid" mixture in D2O the components formed a stable complex. At high Mg2+ concentration a partial disarrangement of stacking interactions in poly-A occurred that might be a consequence of the incorporation of nucleic bases into hydrophobic membrane phase.