The retina is more susceptible than the brain and the liver to the incorporation oftransisomers of DHA in rats consumingtransisomers of alpha-linolenic acid

Abstract

-Trans polyunsaturated fatty acids are formed during heat treatments of vegetable oils from polyunsaturated fatty acids containing cis double bonds. After dietary intake, they are distributed in the body and are incorporated into nervous tissues including the retina. Since nervous tissues are known to be rich in n-3 fatty acids such as docosahexaenoic acid (DHA), we studied the ability of the retina and the brain to incorporate trans isomers of DHA formed in vivo from the dietary precursor trans α-linolenic acid. Wistar rats were fed with trans isomers of α-linolenic acid for 21 months. A linear incorporation of trans DHA and a decrease in cis DHA was observed in the retina, whereas no major changes were observed in the brain. In parallel to the modifications in retinal cis and trans DHA levels, the retinal functionality evaluated by the electroretinogram showed defects in animals that consumed trans α-linolenic acid. These results suggest that the mechanisms leading to the incorporation of cis and trans fatty acids are quite different in the retina when compared to the brain and the liver, the retina being more susceptible to changes in the dietary lipid contribution.dietary trans polyunsaturated fatty acids / rat / retina / cerebral cortex / electroretinography

Severity of middle cerebral artery occlusion determines retinal deficits in rats

“…The endothelial cells of the retina have been shown to be more susceptible than brain-derived endothelial cells to oxidative stress and increased vascular permeability, as measured by glutathione peroxidase activity, superoxide production and superoxide dismutase levels, and junctional protein levels in bovine endothelial cell cultures (Grammas and Riden, 2003). The retina is also more sensitive than either the brain or the liver to dietary changes in lipid levels, with the retina but not the brain showing an incorporation of trans DHA (Docosahexaenoic acid) and a reduction in cis DHA as well as ERG defects following a diet high in trans fatty acids (Acar et al, 2006). In the event of ischemia, however, the retina is less susceptible than the brain, showing a much greater tolerance time to ischemic injury.…”

Metabolism of trans fatty acid isomers

“…When comparing incorporation of trans PUFA isomers in rat retina and brain during a 21 months feeding study with trans 18:3, Acar et al (2006) showed that, after 6 months, the incorporation of trans DHA was higher in retinal phospholipids since trans DHA represented 0.5% of total fatty acids whereas it was only 0.2% in cerebral cortex. After 21 months of feeding, the level of trans DHA in retina was 1.2% of the total fatty acids while that in the cerebral cortex increased to 0.3% (Figure 1).…”

A 24‐year prospective study of dietary α‐linolenic acid and lethal prostate cancer

“…Trans ALA can be incorporated into plasma lipids and converted to trans long‐chain polyunsaturated fatty acids in humans . Similarly, long‐term feeding rats of a diet high in trans ALA resulted in a significant increase in trans Docosahexaenoic acid (DHA) and a decrease in cis DHA . Therefore, it is possible that high ALA intake in the pre‐PSA era is a marker for trans ALA that promotes prostatic carcinogenesis by interfering with normal DHA function.…”

“…44,47 Similarly, long-term feeding rats of a diet high in trans ALA resulted in a significant increase in trans Docosahexaenoic acid (DHA) and a decrease in cis DHA. 48,49 Therefore, it is possible that high ALA intake in the pre-PSA era is a marker for trans ALA that promotes prostatic carcinogenesis by interfering with normal DHA function. The possibility related to trans ALA, coupled with bias related to PSA screening, may explain why the positive association was mainly evident in the pre-PSA era.…”