Sphingomyelin metabolism in rat liver after chronic dietary replacement of choline by N-aminodeanol

Mariana N. Nikolova-Karakashian, Roger W. Russell, Ruth A. Booth, Donald J. Jenden, Alfred H. Merrill

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Sphingomyelin (SM) is a structural element of cell membranes and lipoproteins, and participates in signal transduction. To determine whether a choline analog (N-amino-N,N-dimethylaminoethanol, N-aminodeanol, NADe) can be substituted for choline in the SM of liver, rats (male, Sprague-Dawley- derived) were fed a diet that was low in choline and methionine, and contained 35.5 mmol of NADe/kg. After 18 months, liver plasma membranes and microsomes contained 48.9 ± 3.6 and 93.6 ± 6.9 nmol/mg protein of phosphatidyl-NADe, respectively, and 3.2 ± 0.2 and 3.5 ± 0.1 nmol/mg protein of ceramide phospho-NADe. The SM content of microsomes from NADe-fed rats was about one-third lower than for the control, and phosphatidylcholine (PC) was reduced by <10%; there was also a small decrease in PC, but not SM, in plasma membranes. In vitro assays of enzymes involved in SM metabolism found no change in PC:ceramide choline-phosphotransferase, but the NADe-fed animals had higher phosphatidylethanolamine: ceramide ethanolaminephosphotransferase activity, greater incorporation of methyl groups from [methyl-3H]-S-adenosyl methionine into SM, and a lower neutral sphingomyelinase activity. These results show that NADe-fed rats form considerable amounts of ceramide phospho- and phosphatidyl-NADe; however, liver plasma membranes retain relatively normal levels of PC and SM, perhaps due to increases in the de novo pathway for SM synthesis and decreases in SM turnover.

Original languageEnglish
Pages (from-to)1764-1770
Number of pages7
JournalJournal of Lipid Research
Volume38
Issue number9
DOIs
StatePublished - Sep 1997

Keywords

  • Ceramide
  • Methylation
  • Sphingomyelin synthase
  • Sphingomyelinase

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology
  • Cell Biology

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