Modulation of tissue prostaglandin synthesizing capacity by increased ratios of dietary alpha-linolenic acid to linoleic acid

Lipids. 1982 Dec;17(12):905-13. doi: 10.1007/BF02534586.


Semipurified diets containing ratios of alpha-linolenic acid (18:3 omega 3) to linoleic acid (18:2 omega 6) of 1/32, 1/7, 1/1, and 3.5/1 in the form of corn oil, soybean oil, soybean/linseed oil mix and linseed oil were fed to rats for 2 months. The first 3 diets were fed to another group of rats for 4 months and to a group through the second generation. Fatty acid analysis of liver and spleen ethanolamine glycerophosphatide revealed that, as the level of 18:3 omega 3 in the diet increased, the elongated, desaturated metabolites of the omega 6 series decreased and the omega 3 series increased. Noteworthy was the depression in the amount of the precursor of the 2-series prostaglandins (PG) as the omega 3 levels increased. Synthesis of PG by liver of rats fed 2 or 4 months markedly decreased, but at 2 months in thymus and spleen, it showed a trend toward decreasing only. Brain slices showed no decrease in PGF2 alpha synthesis after 4 months, but did decrease significantly after feeding the diets to the second generation. Synthesis of PGE2 by spleen homogenate from the second generation also significantly decreased. The replacement of omega 6 series fatty acids by omega 3 series is explained by the effective competition of 18:3 omega 3 over 18:2 omega 6 for the delta 6 desaturase. Depressions in PG synthesis by high dietary 18:3 omega 3 is explained by the competitive inhibition of the PG synthetase complex by 20:5 omega 3 as well as by the decreased levels of 20:4 omega 6.

Publication types

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

MeSH terms

  • Animals
  • Brain / metabolism
  • Diet
  • Fatty Acids / analysis
  • Female
  • Linoleic Acid
  • Linoleic Acids / metabolism*
  • Linoleic Acids / pharmacology
  • Linolenic Acids / metabolism*
  • Linolenic Acids / pharmacology
  • Liver / analysis
  • Male
  • Prostaglandins / biosynthesis*
  • Rats
  • Rats, Inbred Lew
  • Spleen / metabolism
  • Thymus Gland / metabolism
  • alpha-Linolenic Acid


  • Fatty Acids
  • Linoleic Acids
  • Linolenic Acids
  • Prostaglandins
  • alpha-Linolenic Acid
  • Linoleic Acid