Dioctanoylglycerol stimulates accumulation of [methyl-14C]choline and its incorporation into acetylcholine and phosphatidylcholine in a human cholinergic neuroblastoma cell line

Brain Res. 1992 Jul 10;585(1-2):169-76. doi: 10.1016/0006-8993(92)91203-q.

Abstract

Dioctanoylglycerol, a synthetic diacylglycerol, stimulated [14C]choline uptake in cultured human neuroblastoma (LA-N-2) cells. As this effect has not, to our knowledge, been reported before, it was of interest to characterize it in more detail. In the presence of 500 microM dioctanoylglycerol the levels of [14C]choline attained during a 2 hour labeling period were elevated by 78 +/- 12%, while [14C]acetylcholine and long fatty acyl chain [14C]phosphatidylcholine levels increased by 26 +/- 2% and 19 +/- 5%, respectively (mean +/- S.E.M.). Total (long chain plus dioctanoyl-) [14C]phosphatidylcholine was increased by 198 +/- 33%. Kinetic analysis showed that dioctanoylglycerol reduced the apparent Km for choline uptake to 56 +/- 9% of control (n = 4). The Vmax was not significantly altered. The stimulation of [14C]choline accumulation by dioctanoylglycerol was not dependent on protein kinase C activation; the effect was not mimicked by phorbol ester or by 1-oleoyl-2-acetylglycerol, and was not inhibited by the protein kinase C inhibitors H-7 or staurosporine, or by prolonged pretreatment with phorbol 12-myristate 13-acetate. The effect of dioctanoylglycerol was slightly (but not significantly) reduced by EGTA and strongly inhibited by the cell-permeant calcium chelator bis(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)ester. Although these results implicate elevated intracellular calcium in the response, dioctanoylglycerol did not increase phosphatidylinositol hydrolysis in LA-N-2 cells, and its effect was not inhibited by the diacylglycerol kinase inhibitor R 59 022 (which blocks the conversion of diacylglycerol to phosphatidic acid, a known stimulator of phosphatidylinositol hydrolysis).(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylcholine / biosynthesis*
  • Choline / metabolism*
  • Diglycerides / pharmacology*
  • Humans
  • Nervous System Neoplasms / metabolism*
  • Nervous System Neoplasms / pathology
  • Neuroblastoma / metabolism*
  • Neuroblastoma / pathology
  • Osmolar Concentration
  • Parasympathetic Nervous System*
  • Phosphatidylcholines / metabolism*
  • Protein Kinase C / metabolism
  • Tetradecanoylphorbol Acetate / pharmacology
  • Tumor Cells, Cultured

Substances

  • Diglycerides
  • Phosphatidylcholines
  • 1,2-dioctanoylglycerol
  • Protein Kinase C
  • Choline
  • Acetylcholine
  • Tetradecanoylphorbol Acetate