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Incorporation of trans long‐chain n−3 polyunsaturated fatty acids in rat brain structures and retina
Author(s) -
Grandgirard A.,
Bourre J. M.,
Julliard F.,
Homayoun P.,
Dumont O.,
Piciotti M.,
Sebedio J. L.
Publication year - 1994
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02536329
Subject(s) - polyunsaturated fatty acid , docosahexaenoic acid , fatty acid , alpha linolenic acid , cis–trans isomerism , chemistry , isomerization , eicosapentaenoic acid , lactation , biochemistry , stereochemistry , biology , pregnancy , genetics , catalysis
During heat treatment, polyunsaturated fatty acids and specifically 18∶3n−3 can undergo geometrical isomerization. In rat tissues, 18∶3 Δ9 c , 12 c , 15 t , one of the trans isomers of linolenic acid, can be desaturated and elongated to give trans isomers of eicosapentaenoic and docosahexaenoic acids. The present study was undertaken to determine whether such compounds are incorporated into brain structures that are rich in n−3 long‐chain polyunsaturated fatty acids. Two fractions enriched in trans isomers of α‐linolenic acid were prepared and fed to female adult rats during gestation and lactation. The pups were killed at weaning. Synaptosomes, brain microvessees and retina were shown to contain the highest levels (about 0.5% of total fatty acids) of the trans isomer of docosahexaenoic acid (22∶6 Δ4 c , 7 c , 10 c , 13 c , 16 c , 19 t ). This compound was also observed in myelin and sciatic nerve, but to a lesser extent (0.1% of total fatty acids). However, the ratios of 22∶6 trans to 22∶6 cis were similar in all the tissues studied. When the diet was deficient in α‐linolenic acid, the incorporation of trans isomers was apparently doubled. However, comparison of the ratios of trans 18∶3n−3 to cis 18∶3n−3 in the diet revealed that the cis n−3 fatty acids were more easily desaturated and elongated to 22∶6n−3 than the corresponding trans n−3 fatty acids. An increase in 22∶5n−6 was thus observed, as has previously been described in n−3 fatty acid deficiency. These results encourage further studies to determine whether or not incorporations of such trans isomers into tissues may have physiological implications.