title: Turnover of phosphatidyl choline and changes in enzymatic activity in cell membranes of the CNS during early myelination.
abstract: Subfractions of fraction A, which floats on top on 0.8 M sucrose in the classical density gradient used for the isolation of brain subcellular fractions (A1 corresponding in adult rats to myelin and A2 which corresponds to the myelin-like fraction), were studied in comparison to other brain subcellular fractions in 5 day old rats and at different stages of development, up to 60 days of age. Variations in the enzymatic activity of acetylcholinesterase, non-specific cholinesterase and 2',3'-Cyclic nucleotide phosphohydrolase, changes in lipid and protein composition and turnover of phosphatidyl choline were investigated. Results indicate that fractions A1 and A2 obtained prior to the beginning of myelination could be composed of fragments of the oligodendroglial cell plasma membranes, and that both fractions undergo substantial changes in chemical composition, enzymatic activity and in turnover of phosphatidyl choline during maturation. In vivo experiments at short times, using radioactive choline as a precursor of phosphatidylcholine suggest that membrane fragments isolated in fraction A2 are precursors of those isolated in fraction A1 at all ages.
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000378:metabolism; D000110:Acetylcholinesterase / Q000378:metabolism; D000375:Aging; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology*; D002554:Cerebrosides / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D002802:Cholinesterases / Q000378:metabolism; D005260:Female; D008297:Male; D008861:Microsomes / Q000201:enzymology; D009186:Myelin Sheath / Q000201:enzymology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009836:Oligodendroglia / Q000201:enzymology; D010713:Phosphatidylcholines / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D002554:Cerebrosides; D009419:Nerve Tissue Proteins; D010713:Phosphatidylcholines; D010743:Phospholipids; D002784:Cholesterol; D000110:Acetylcholinesterase; D002802:Cholinesterases; D015106:3',5'-Cyclic-GMP Phosphodiesterases