Enrichment of maternal diet with conjugated linoleic acids influences desaturases activity and fatty acids profile in livers and hepatic microsomes of the offspring with 7,12-dimethylbenz[a]anthracene-induced mammary tumors.

The aim of this study was to assess the influence of diet supplementation of pregnant and breast-feeding female Sprague-Dawley rats with conjugated linoleic acids (CLA) on the Δ6- and Δ5-desaturase activity in hepatic microsomes as well as on fatty acids profile and lipids peroxidation in liver and hepatic microsomes of the progeny with chemically induced mammary tumors. Rats were divided into two groups with different diet supplementation (vegetable oil (which did not contain CLA) or CLA). Their female offspring was divided within these groups into two subgroups: (1)--fed the same diet as mothers (K1 - oil, 01 - CLA), and (2)--fed the standard fodder (K2, O2). At 50th day of life, the progeny obtained carcinogenic agent (7,12-dimethylbenz[a]anthracene). Higher supply of CLA in diet of mothers resulted in lower susceptibility to chemically induced mammary tumors in their offspring (p = 0.0322). It also influenced the fatty acids profile in livers and in hepatic microsomes, especially polyunsaturated n3 and n6 fatty acids. CLA inhibited the activity of the desaturases, which confirmed that CLA can reduce the level of arachidonic acid directly, reducing linoleic acid content in membranes, or indirectly, through the regulation of its metabolism. We were unable to confirm or deny the antioxidative properties of CLA. Our results indicate that the higher supply of CLA in mothers' diet during pregnancy and breastfeeding causes their incorporation into tissues of children, changes the efficiency of fatty acids metabolism and exerts health-promoting effect in their adult life reducing the breast cancer risk.

Inhibition of delta-6 desaturase reverses cardiolipin remodeling and prevents contractile dysfunction in the aged mouse heart without altering mitochondrial respiratory function.

Aging results in a redistribution of polyunsaturated fatty acids (PUFAs) in myocardial phospholipids. In particular, a selective loss of linoleic acid (18:2n6) with reciprocal increases of long-chain PUFAs (eg, arachidonic and docosahexaenoic acids) in the mitochondrial phospholipid cardiolipin correlates with cardiac mitochondrial dysfunction and contractile impairment in aging and related pathologies. In this study, we demonstrate a reversal of this aged-related PUFA redistribution pattern in cardiac mitochondria from aged (25 months) C57Bl/6 mice by inhibition of delta-6 desaturase, the rate limiting enzyme in long-chain PUFA biosynthesis. Interestingly, delta-6 desaturase inhibition had no effect on age-related mitochondrial respiratory dysfunction, H2O2 release, or lipid peroxidation but markedly attenuated cardiac dilatation, hypertrophy, and contractile dysfunction in aged mice. Taken together, our studies indicate that PUFA metabolism strongly influences phospholipid remodeling and cardiac function but dissociates these processes from mitochondrial respiratory dysfunction and oxidant production in the aged mouse heart.

Delta-6-desaturase links polyunsaturated fatty acid metabolism with phospholipid remodeling and disease progression in heart failure.

BACKGROUND: Remodeling of myocardial phospholipids has been reported in various forms of heart failure for decades, but the mechanism and pathophysiological relevance of this phenomenon have remained unclear. We examined the hypothesis that δ-6 desaturase (D6D), the rate-limiting enzyme in long-chain polyunsaturated fatty acid biosynthesis, mediates the signature pattern of fatty acid redistribution observed in myocardial phospholipids after chronic pressure overload and explored plausible links between this process and disease pathogenesis. METHODS AND RESULTS: Compositional analysis of phospholipids from hearts explanted from patients with dilated cardiomyopathy revealed elevated polyunsaturated fatty acid product/precursor ratios reflective of D6D hyperactivity, manifesting primarily as lower levels of linoleic acid with reciprocally higher levels of arachidonic and docosahexaenoic acids. This pattern of remodeling was attenuated in failing hearts chronically unloaded with a left ventricular assist device. Chronic inhibition of D6D in vivo reversed similar patterns of myocardial polyunsaturated fatty acid redistribution in rat models of pressure overload and hypertensive heart disease and significantly attenuated cardiac hypertrophy, fibrosis, and contractile dysfunction in both models. D6D inhibition also attenuated myocardial elevations in pathogenic eicosanoid species, lipid peroxidation, and extracellular receptor kinase 1/2 activation; normalized cardiolipin composition in mitochondria; reduced circulating levels of inflammatory cytokines; and elicited model-specific effects on cardiac mitochondrial respiratory efficiency, nuclear factor κ B activation, and caspase activities. CONCLUSIONS: These studies demonstrate a pivotal role of essential fatty acid metabolism in myocardial phospholipid remodeling induced by hemodynamic stress and reveal novel links between this phenomenon and the propagation of multiple pathogenic systems involved in maladaptive cardiac remodeling and contractile dysfunction [corrected].

Inhibiting delta-6 desaturase activity suppresses tumor growth in mice.

Recent studies have shown that a tumor-supportive microenvironment is characterized by high levels of pro-inflammatory and pro-angiogenic eicosanoids derived from omega-6 (n-6) arachidonic acid (AA). Although the metabolic pathways (COX, LOX, and P450) that generate these n-6 AA eicosanoids have been targeted, the role of endogenous AA production in tumorigenesis remains unexplored. Delta-6 desaturase (D6D) is the rate-limiting enzyme responsible for the synthesis of n-6 AA and increased D6D activity can lead to enhanced n-6 AA production. Here, we show that D6D activity is upregulated during melanoma and lung tumor growth and that suppressing D6D activity, either by RNAi knockdown or a specific D6D inhibitor, dramatically reduces tumor growth. Accordingly, the content of AA and AA-derived tumor-promoting metabolites is significantly decreased. Angiogenesis and inflammatory status are also reduced. These results identify D6D as a key factor for tumor growth and as a potential target for cancer therapy and prevention.

A multiplexed cell assay in HepG2 cells for the identification of delta-5, delta-6, and delta-9 desaturase and elongase inhibitors.

A multiplexed cell assay has been optimized to measure the activities of fatty acyl-CoA elongase, delta-5 desaturase (Delta5D), delta-6 desaturase (Delta6D), and delta-9 desaturase (Delta9D) together using (14)C-labeled tracers in HepG2 cells, which express the human stearoyl-CoA desaturase-1 isoform (SCD1) exclusively. The Delta5 and Delta9 desaturase activities are indexed by the efficient conversion of [1-(14)C]-eicosatrienoic acid (C20:3, cis-8,11,14) to (14)C-arachidonic acid (C20:4, cis-5,8,11,14) and the conversion of [1-(14)C]-stearic acid to (14)C-oleic acid (C18:1, cis-9), respectively. CP-74006 potently blocks the Delta5D activity with an IC(50) value of 20 nM and simplifies the metabolism of [1-(14)C]-alpha-linolenate (C18:3, cis-9,12,15) by accumulating (14)C-eicosatetraenoic acid (C20:4, cis-8,11,14,17) as the major (14)C-eicosatrienoic acid (C20:3, cis-11,14,17) and (14)C-docosatetraenoic acid (C22:4, cis-10,13,16,19) as the minor metabolites through Delta6 desaturation and elongation. This simplified metabolite spectrum enables the delineation of the Delta6D activity by comparing the combined Delta6D/elongase activity index of the (14)C-(C20:4/C18:3) ratio with the corresponding elongation index of the (14)C-(C20:3/C18:3) ratio following compound treatment. SC-26196 and sterculic acid specifically inhibit the Delta6D and Delta9D activities with an IC(50) value of 0.1 microM and 0.9 microM, respectively. This medium-throughput cell assay provides an efficient tool in the identification of specific desaturase and elongase inhibitors.

Parenteral lipid emulsions based on olive oil compared with soybean oil in preterm (<28 weeks' gestation) neonates: a randomised controlled trial.

BACKGROUND: : New olive oil-based (OL) lipid emulsions (olive:soy oil = 4:1) have lower polyunsaturated fatty acid (PUFA) (20% vs 60%) and higher vitamin E content (an antioxidant) compared with traditional soybean oil (SO) emulsions. OBJECTIVE: : Compare efficacy and safety of OL with SO emulsions in preterm neonates (<28 weeks) at high risk for oxidative stress. PATIENTS AND METHODS: : Preterm neonates (gestation 23-<28 weeks) were randomised to receive OL or SO emulsion for 5 days using a standard protocol in a tertiary perinatal centre (King Edward Memorial Hospital for Women, Perth, Western Australia). Investigators and outcome assessors were masked to allocation. Plasma F2-isoprostanes (lipid peroxidation marker), plasma, and red blood cell fatty acids were measured before and after the study. Safety was monitored by liver function tests. RESULTS: : Forty-four of 50 participants (OL-23, SO-21) completed the study. Both emulsions were well tolerated with no significant adverse events. F2-isoprostane levels were comparable at baseline and study end. Oleic and linoleic acid levels were significantly high on day 6 in OL and SO groups, respectively. Long-chain PUFA levels were similar between groups despite the lower PUFA content of OL. The olive oil-based group had significantly higher levels of C18:4n-3, suggesting Delta6-desaturase enzyme inhibition in the SO group. CONCLUSIONS: : Olive oil-based emulsion was safe and well tolerated by preterm neonates. Similar long-chain PUFA levels were achieved in the OL group despite significantly lower amount of PUFA content; however, there was no difference in lipid peroxidation (F2-isoprostane levels). Large trials are needed to confirm these benefits.

Conjugated linoleic acid-induced fat loss dependence on Delta6-desaturase or cyclooxygenase.

OBJECTIVE: To determine whether conjugated linoleic acid (CLA)-induced body fat loss is dependent upon metabolism of CLA by Delta6-desaturase, cyclooxygenase, or lipoxygenase. METHODS AND PROCEDURES: Mice were fed diets with or without CLA and inhibitors to either Delta6-desaturase (SC-26196), cyclooxygenase (aspirin), or lipoxygenase (nordihydroguaiaretic acid (NDGA)) for 2 weeks. Body fat percent, lean mass, fat pad weights, liver weight, and fatty acid concentrations were determined. A Delta6-desaturase index was calculated, and adipose tissue prostaglandin E(2) (PGE(2)) and leukotriene B(4) (LTB(4)) concentrations were determined to confirm enzyme inhibition. RESULTS: Inhibition of Delta6-desaturase and cyclooxygenase were confirmed. CLA caused a loss of body fat (P < 0.001). The body fat loss was blocked (P = 0.08) by the Delta6-desaturase inhibitor at a dose that decreased (P < 0.05) the calculated index. Aspirin and NDGA had no effect on body fat and did not interact with CLA. DISCUSSION: Inhibition of Delta6-desaturase prevented CLA from being able to cause a body fat loss. Therefore, a desaturated metabolite of CLA appears to be involved in the CLA antiobesity effect. This effect of CLA does not seem dependent upon cyclooxygenase. Because lipoxygenase activity was not blocked by NDGA, we cannot draw conclusions about its importance in mediating the antiobesity effect of CLA.