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Delta 6-desaturase activity in liver microsomes of rats fed diets enriched with cholesterol and/or omega 3 fatty acids.
Biochem J. 1988 Jan 15; 249(2):351-6.BJ

Abstract

The effect of feeding semipurified diets enriched in linseed (rich in C18:3, omega 3 fatty acid) or fish (rich in C20:5, omega 3 and C22:6, omega 3 fatty acid) oil with and without cholesterol supplementation on the desaturation of linoleic acid (C18:2, omega 6) by rat liver microsomal fractions was investigated. Animals fed diets supplemented with beef tallow were used as equal-energy controls. Both linseed-oil and fish-oil diets, without added cholesterol, decrease conversion of C18:2, omega 6 fatty acid to gamma-linolenic acid (C18:3, omega 6). Reduction in delta 6-desaturation was significantly greater for animals fed the diet containing fish oil than with animals fed the linseed-oil diet. The major effect of cholesterol supplementation was to decrease the rate of desaturation of C18:2, omega 6, when fed in combination with the beef-tallow diet, whereas delta 6-desaturation was unaffected when cholesterol was fed along with diets high in omega 3 fatty acids (linseed oil or fish oil). The activity of the delta 6-desaturase in vitro is consistent with the fatty acid composition observed for the microsomal membranes on which this enzyme is localized. Dietary linseed oil and fish oil lowered the arachidonic (C20:4, omega 6) acid content of rat liver microsomes, with an accompanying increase in membrane eicosapentaenoic (C20:5, omega 3) and docosahexaenoic (C22:6, omega 3) acid content, in comparison with the group fed beef tallow. Inclusion of cholesterol into the beef-tallow or linseed-oil diets resulted in decreased membrane C20:4, omega 6-fatty-acid content, with concomitant increase in C18:2, omega 6-fatty-acid content. However, addition of cholesterol to the fish-oil diet did not alter the microsomal membrane content of C20:4, omega 6 fatty acid. Thus it is suggested that (1) the decrease in prostaglandin E2, thromboxane and prostacyclin levels generally observed after fish-oil consumption may be at least partly due to inhibition of C20:4, omega 6-fatty-acid synthesis from C18:2, omega 6 fatty acid; and (2) consumption of fish oil prevents the further decrease in C20:4, omega 6-fatty-acid levels by dietary cholesterol that is apparent when cholesterol is fed in combination with diets high in saturated fat or C18:3, omega 3 fatty acid.

Authors+Show Affiliations

Nutrition and Metabolism Research Group, University of Alberta, Edmonton, Canada.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

3342019

Citation

Garg, M L., et al. "Delta 6-desaturase Activity in Liver Microsomes of Rats Fed Diets Enriched With Cholesterol And/or Omega 3 Fatty Acids." The Biochemical Journal, vol. 249, no. 2, 1988, pp. 351-6.
Garg ML, Sebokova E, Thomson AB, et al. Delta 6-desaturase activity in liver microsomes of rats fed diets enriched with cholesterol and/or omega 3 fatty acids. Biochem J. 1988;249(2):351-6.
Garg, M. L., Sebokova, E., Thomson, A. B., & Clandinin, M. T. (1988). Delta 6-desaturase activity in liver microsomes of rats fed diets enriched with cholesterol and/or omega 3 fatty acids. The Biochemical Journal, 249(2), 351-6.
Garg ML, et al. Delta 6-desaturase Activity in Liver Microsomes of Rats Fed Diets Enriched With Cholesterol And/or Omega 3 Fatty Acids. Biochem J. 1988 Jan 15;249(2):351-6. PubMed PMID: 3342019.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Delta 6-desaturase activity in liver microsomes of rats fed diets enriched with cholesterol and/or omega 3 fatty acids. AU - Garg,M L, AU - Sebokova,E, AU - Thomson,A B, AU - Clandinin,M T, PY - 1988/1/15/pubmed PY - 1988/1/15/medline PY - 1988/1/15/entrez SP - 351 EP - 6 JF - The Biochemical journal JO - Biochem J VL - 249 IS - 2 N2 - The effect of feeding semipurified diets enriched in linseed (rich in C18:3, omega 3 fatty acid) or fish (rich in C20:5, omega 3 and C22:6, omega 3 fatty acid) oil with and without cholesterol supplementation on the desaturation of linoleic acid (C18:2, omega 6) by rat liver microsomal fractions was investigated. Animals fed diets supplemented with beef tallow were used as equal-energy controls. Both linseed-oil and fish-oil diets, without added cholesterol, decrease conversion of C18:2, omega 6 fatty acid to gamma-linolenic acid (C18:3, omega 6). Reduction in delta 6-desaturation was significantly greater for animals fed the diet containing fish oil than with animals fed the linseed-oil diet. The major effect of cholesterol supplementation was to decrease the rate of desaturation of C18:2, omega 6, when fed in combination with the beef-tallow diet, whereas delta 6-desaturation was unaffected when cholesterol was fed along with diets high in omega 3 fatty acids (linseed oil or fish oil). The activity of the delta 6-desaturase in vitro is consistent with the fatty acid composition observed for the microsomal membranes on which this enzyme is localized. Dietary linseed oil and fish oil lowered the arachidonic (C20:4, omega 6) acid content of rat liver microsomes, with an accompanying increase in membrane eicosapentaenoic (C20:5, omega 3) and docosahexaenoic (C22:6, omega 3) acid content, in comparison with the group fed beef tallow. Inclusion of cholesterol into the beef-tallow or linseed-oil diets resulted in decreased membrane C20:4, omega 6-fatty-acid content, with concomitant increase in C18:2, omega 6-fatty-acid content. However, addition of cholesterol to the fish-oil diet did not alter the microsomal membrane content of C20:4, omega 6 fatty acid. Thus it is suggested that (1) the decrease in prostaglandin E2, thromboxane and prostacyclin levels generally observed after fish-oil consumption may be at least partly due to inhibition of C20:4, omega 6-fatty-acid synthesis from C18:2, omega 6 fatty acid; and (2) consumption of fish oil prevents the further decrease in C20:4, omega 6-fatty-acid levels by dietary cholesterol that is apparent when cholesterol is fed in combination with diets high in saturated fat or C18:3, omega 3 fatty acid. SN - 0264-6021 UR - https://www.unboundmedicine.com/medline/citation/3342019/Delta_6_desaturase_activity_in_liver_microsomes_of_rats_fed_diets_enriched_with_cholesterol_and/or_omega_3_fatty_acids_ L2 - https://portlandpress.com/biochemj/article-lookup/doi/10.1042/bj2490351 DB - PRIME DP - Unbound Medicine ER -