Occurrence and biosynthesis of endogenous cannabinoid precursor, N-arachidonoyl phosphatidylethanolamine, in rat brain

J Neurosci. 1997 Feb 15;17(4):1226-42. doi: 10.1523/JNEUROSCI.17-04-01226.1997.

Abstract

It has been suggested that anandamide (N-arachidonoylethanolamine), an endogenous cannabinoid substance, may be produced through Ca2+-stimulated hydrolysis of the phosphatidylethanolamine (PE) derivative N-arachidonoyl PE. The presence of N-arachidonoyl PE in adult brain tissue and the enzyme pathways that underlie its biosynthesis are, however, still undetermined. We report here that rat brain tissue contains both anandamide (11 +/- 7 pmol/gm wet tissue) and N-arachidonoyl PE (22 +/- 16 pmol/gm), as assessed by gas chromatography/mass spectrometry. We describe a N-acyltransferase activity in brain that catalyzes the biosynthesis of N-arachidonoyl PE by transferring an arachidonate group from the sn-1 carbon of phospholipids to the amino group of PE. We also show that sn-1 arachidonoyl phospholipids are present in brain, where they constitute approximately 0.5% of total phospholipids. N-acyltransferase activity is Ca2+ dependent and is enriched in brain and testis. Within the brain, N-acyltransferase activity is highest in brainstem; intermediate in cortex, striatum, hippocampus, medulla, and cerebellum; and lowest in thalamus, hypothalamus, and olfactory bulb. Pharmacological inhibition of N-acyltransferase activity in primary cultures of cortical neurons prevents Ca2+-stimulated N-arachidonoyl PE biosynthesis. Our results demonstrate, therefore, that rat brain tissue contains the complement of enzymatic activity and lipid substrates necessary for the biosynthesis of the anandamide precursor N-arachidonoyl PE. They also suggest that biosynthesis of N-arachidonoyl PE and formation of anandamide are tightly coupled processes, which may concomitantly be stimulated by elevations in intracellular Ca2+ occurring during neural activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acyltransferases / metabolism
  • Animals
  • Arachidonic Acids / metabolism
  • Brain / metabolism*
  • Cannabinoids / metabolism*
  • Endocannabinoids
  • Enzymes / metabolism
  • Lipid Metabolism
  • Male
  • Phosphatidylethanolamines / metabolism*
  • Phospholipids / metabolism
  • Polyunsaturated Alkamides
  • Prodrugs / metabolism*
  • Rats
  • Rats, Wistar
  • Tissue Distribution

Substances

  • Arachidonic Acids
  • Cannabinoids
  • Endocannabinoids
  • Enzymes
  • N-arachidonylphosphatidylethanolamine
  • Phosphatidylethanolamines
  • Phospholipids
  • Polyunsaturated Alkamides
  • Prodrugs
  • Acyltransferases
  • anandamide