Differential utilization of long chain fatty acids during triacylglycerol depletion. I. Rat heart after ischemic perfusion

Differential utilization of hepatic and myocardial fatty acids during forced molt of laying hens

Feed was totally withdrawn from laying hens (n = 30, Hy-Line Brown, 608 d of age, 2.04 +/- 0.07 kg of mean BW) to induce molting. Ten birds were slaughtered on d 0 and 12, and the hepatic and myocardial triacylglycerol (TAG) and phospholipid (PL) fatty acid composition, as well as the tissue malondialdehyde (MDA) and reduced glutathione (GSH) concentrations were determined. The liver TAG and PL contents decreased by 24.3 and 16.1%, respectively, whereas the myocardial TAG content increased by 12%, and the PL decreased by 22%. Liver TAG fraction has been found to selectively retain arachidonic and docosahexanoic acids. Hepatic PL fatty acids were markedly affected by fasting; these changes reflected an altered PL metabolism, primarily degradation. Liver TAG compensated for the absence of dietary fatty acids, because we found practically no qualitative alteration in myocardial TAG. The lipid peroxide status, as measured with MDA content was, accordingly, increased in the liver tissue only. In the myocardial PL fatty acids, preferred conservation of arachidonic acid was shown, and it was hypothesized that energy deprivation of cardiomyocytes strongly improved PL degradation in fasting laying hens and influenced PL homeostasis. Generally the physiological recovery from forced molting associated with fasting is complete; however, the use of total feed withdrawal methods should be reevaluated.

Differential utilization of long chain fatty acids during fasting-induced triacylglycerol depletion. III. Comparison of n-3 and n-6 fatty acids in rat plasma and liver

Previous research has shown that arachidonic acid (20:4(n-6)) is preferentially retained in liver triacylglycerol in fasted compared to fed rats consuming a diet containing n-6 fatty acids. It was hypothesized that eicosapentaenoic (20:5(n-3)) and docosahexaneoic acids (22:6(n-3)) would be similarly retained in liver and plasma triacylglycerol of fasted rats consuming a diet containing n-3 fatty acids. In comparison with fed rats, it was observed that in partially fasted rats consuming diets which contained 5% sunflower oil (78% 18:2(n-6)) or 5% marine fish oil (30% 20:5(n-3) and 22:6(n-3)), both liver and plasma had significantly depleted triacylglycerol levels containing higher proportions of both arachidonic and docosahexaneoic acids but a lower proportion of eicosapentaenoic acid (marine fish oil group only). Separation of liver and plasma triacylglycerol by silicic acid column chromatography and silver nitrate TLC showed that the majority of long chain fatty acids utilized during fasting were derived from the triacylglycerol subclasses containing palmitic acid (16:0), palmitoleic acid (16:1(n-7)) and oleic acid (18:1(n-9)) with retention o both highly saturated and polyunsaturated subclasses. Greater utilization of eicosapentaenoic acid than either arachidonic acid or docosahexaenoic acid during fasting may be due to triacylglycerol speciation of the former with readily oxidized monounsaturated fatty acids.

Age-related changes of lipid fractions and total fatty acids in liver lipids and heart lipids of female and male rats aged 37-1200 days (liver) and 331-1200 days (heart)

1. Total lipids and the lipid fractions cholesterol ester, triacylglycerol, free cholesterol, free fatty acids and phospholipids, as well as the fatty acid patterns of total lipids, were measured in liver homogenates of female and male rats (Wistar SPF, strain Hannover) aged 37-1213 days. 2. The same parameters were measured in the apex of the heart in female and male rats aged 331-1213 days. 3. All parameters were monitored every 49th day. Five female and five male animals were used in each experiment. 4. The lipid fractions in liver showed a positive linear regression vs age, whereas all lipids in rat heart showed a negative regression vs age in both sexes. 5. The significance of regression vs age of fatty acids was much less than that in the lipid fractions of liver and heart of these animals.