Carrier-mediated transport and enzymatic hydrolysis of the endogenous cannabinoid 2-arachidonylglycerol

Neuroreport. 2000 Apr 27;11(6):1231-5. doi: 10.1097/00001756-200004270-00018.

Abstract

The human astrocytoma cell line CCF-STTGI accumulates [3H]2-AG through an Na(+)- and energy-independent process, with a Km of 0.7 +/- 0.1 microM. Non-radioactive 2-AG, anandamide or the anandamide transport inhibitor 4-hydroxyphenyl arachidonamide inhibit [3H]2-AG uptake with half-maximal inhibitory concentrations (IC50) of 5.5 +/- 1.0 microM, 4.2 +/- 0.3 microM and 1.8 = 0.1 microM, respectively. A variety of lipid transport substrates and inhibitors interfere with neither [3H]2-AG nor [3H]anandamide uptake. These results suggest that 2-AG and anandamide are internalized in astrocytoma cells through a common carrier-mediated mechanism. After incubation with [3H]2-AG, radioactivity is recovered in phospholipids, monoacylglycerols (unmetabolized [3H]2-AG), free fatty acids ([3H]arachidonate) and, to a minor extent, diacylglycerols and triacylglycerols. Arachidonic acid (100 microM) and triacsin C (10 microM), an acyl-CoA synthetase inhibitor, prevent incorporation of [3H]arachidonic acid in phospholipids and significantly reduce [3H]2-AG transport. Thus, the driving force for 2-AG internalization may derive from the hydrolysis of 2-AG to arachidonate and the subsequent incorporation of this fatty acid into phospholipids.

Publication types

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

MeSH terms

  • Arachidonic Acid / metabolism
  • Arachidonic Acid / pharmacology
  • Arachidonic Acids / metabolism
  • Arachidonic Acids / pharmacology
  • Astrocytoma / enzymology*
  • Astrocytoma / pathology
  • Binding, Competitive / drug effects
  • Biological Transport / drug effects
  • Calcium Channel Blockers / metabolism
  • Carrier Proteins / metabolism*
  • Chromatography, Thin Layer
  • Dose-Response Relationship, Drug
  • Endocannabinoids
  • Enzyme Inhibitors / pharmacology
  • Glycerides / metabolism*
  • Glycerides / pharmacology
  • Glycerol / metabolism
  • Humans
  • Hydrolysis
  • Intracellular Fluid / drug effects
  • Intracellular Fluid / enzymology
  • Lipid Metabolism
  • Lipids / analysis
  • Neurotransmitter Agents / metabolism*
  • Phospholipids / analysis
  • Phospholipids / metabolism
  • Polyunsaturated Alkamides
  • Triazenes / pharmacology
  • Tritium
  • Tumor Cells, Cultured

Substances

  • Arachidonic Acids
  • Calcium Channel Blockers
  • Carrier Proteins
  • Endocannabinoids
  • Enzyme Inhibitors
  • Glycerides
  • Lipids
  • Neurotransmitter Agents
  • Phospholipids
  • Polyunsaturated Alkamides
  • Triazenes
  • Tritium
  • Arachidonic Acid
  • triacsin C
  • glyceryl 2-arachidonate
  • Glycerol
  • anandamide
  • N-(4-hydroxyphenyl)arachidonylamide