6533b852fe1ef96bd12ab40b

RESEARCH PRODUCT

Long term effect of dietary alpha-linolenic (ALA) or docosahexaenoic acid (DHA) on the incorporation of of DHA and its influence in vivo on the rat heart

subject

description

National audience; The present study was designed to evaluate if a high (20% of the fatty acids) and long term supply of dietary ALA as supplied in the diet by whole grain extruded linseed (Valorex) can increase the endogenous pro- duction of the long-chain n-3 PUFAs in healthy adult rats, and influence heart rate and adrenergic response like a DHA-rich diet. The enrichment in DHA was evaluated using fatty acid analysis by GC in various membranes (heart, brain, .. .) after 2, 4, 6 and 8 months of feeding (n = 7) from male Wistar rats randomly assigned to three groups (n = 36) and fed a normal fat diet (NFD), a ALA-rich diet (ALA) or a DHA-rich diet (DHA). In parallel three groups (n = 8) were used to determine the heart rate (HR) from ECG record- ings in anaesthetized rats still after the same feeding periods (adrenergic stimulation challenge). Our results showed that dietary ALA allowed a significant increase of DHA (and DPA) in cerebral and cardiac membranes, and in a lesser extent in other tissues, as compared to NFD fed rats. The ALA-rich diet allowed an enrich- ment of DHA in heart about 10%, while with DHA- rich diet it reached 20% as compared to NFD (4%). Whatever the diet, DHA decrease with age. Neverthe- less a supply of pure DHA maintained this amount over 15%, limit to get its anti-arrythmic effects. The fatty acid-induced print was established after the 2- month feeding period in animals and continued in the course of the experiment, heart from old ALA-fed rats remained richer in DHA than those from young NFD rats. Moreover our results showed a decrease in basal heart rate with ALA (395 ± 24.9 bpm) even if it was not as wide as those of DHA (375 ± 26.4 versus 407 ± 36.7 bpm for NFD). Our results suggested that the regulation of heart rate by nuro-humoral mediators may be controlled by lower content of DHA, such as those brought by a dietary supply of extruded linseed (ALA).