The Metabolism and Distribution of Docosapentaenoic Acid (n-6) in the Liver and Testis of Growing Rats

Abstract

To investigate the metabolism and distribution of docosapentaenoic acid (22:5n-6, DPA) in the liver and testis of growing rats, 22:5n-6 was administered to their dams. Newborn rats with a low hepatic arachidonic acid (20:4n-6, AA) level were generated by administrating a diet rich in docosahexaenoic acid (22:6n-3, DHA) but n-6 fatty acid (FA) free to pregnant dams. After parturition, 22:5n-6 or linoleic acid (18:2n-6, LA) was administered with a high level of 22:6n-3 to the dams until weaning. At weaning, the hepatic 20:4n-6 level was significantly highest in the DPA-DHA but not LA-DHA diet-fed animals. The hepatic delta-6 desaturase (D6D) mRNA abundance was significantly lower in both the LA-DHA and DPA-DHA diet-fed animals, connoted with the 20:4n-6 content recovered by 22:5n-6 that did not involve D6D and supporting the occurrence of retroconversion in the liver of the growing rats. The low D6D level in the 3-week-old testis was not in proportion to the elevated 22:5n-6 level, implying that early testicular 22:5n-6 accumulation might require supply from the circulation system.

Metabolic fate of docosahexaenoic acid (DHA; 22:6n‐3) in human cells: direct retroconversion of DHA to eicosapentaenoic acid (20:5n‐3) dominates over elongation to tetracosahexaenoic acid (24:6n‐3)

“…Figure 1 shows chromatogram results comparing MCF7 and Y79 cells incubated for 24 h with 20 lM 13 C-22:6n-3. The labeled fatty acids found in these cells were 13 C-20:5n-3, 13 C-22:6n-3, and 13 C-24:6n-3 (tetracosahexaenoic acid). The fatty acid 13 Figure S1 shows chromatograms for one replicate of each treatment in all four cells lines and with 24 h incubations with 20 or 100 lM 13 C-22:6n-3.…”

“…The labeled fatty acids found in these cells were 13 C-20:5n-3, 13 C-22:6n-3, and 13 C-24:6n-3 (tetracosahexaenoic acid). The fatty acid 13 Figure S1 shows chromatograms for one replicate of each treatment in all four cells lines and with 24 h incubations with 20 or 100 lM 13 C-22:6n-3. In nonneuronal cells MCF7 and HepG2, the chain-shortened product 13 C-20:5n-3 predominates over 13 C-24:6n-3 at both concentrations.…”

“…-20:5n-3 and 13 C-24:6n-3. All four cell lines dosed with 20 or 100 lM 13 C-22:6n-3 and incubated for 24 h show significantly more of the retroconverted product13 C-20:5n-3 compared to the elongation 13 C-24:6n-3 product, with the exception of the Y79 cells dosed at 20 lM. The relative abundance of 13 C-20:5n-3 vs 13 C-24:6n-3 was 5-6-fold in MCF7 cells and ≥ 2-fold in HepG2 cells.…”

Effects of graded levels of arachidonic acid on the reproductive physiology of Senegalese sole (Solea senegalensis): Fatty acid composition, prostaglandins and steroid levels in the blood of broodstock bred in captivity

“…Increasing ARA levels in blood had as a consequence an increase in the levels of 22:4n-6 and 22:5n-6 in males, a consequence of the elongation of ARA to 22:4n-6 and desaturation of this fatty acid to 22:5n-6 [31]. Long chain PUFAs (n-3 and n-6) have been detected in the spermatozoa of mammals [7,13,29,30,60] and in the gonads of male marine fish (i.e., wild Senegalese sole) being these fatty acids, 22:4n-6 and 22:5n-6 closely related to the sperm membrane fluidity needed to participate in the membrane fusion events associated with fertilization [30]. The diets used in the experiment were formulated using high quality northern fish oil (G. Rosenlund, pers.…”

Docosapentaenoic acid (22:5n-3): A review of its biological effects

“…There is another isomer of DPA which is an n-6 fatty acid. The n-6 DPA content is low in most mammalian tissues, except testes tissue (32,33). In fish & fish oils, the n-3 isomer of DPA is substantially higher than the n-6 isomer (34).…”