BackgroundObesity is commonly associated with diabetes, cardiovascular diseases and cancer. The purpose of this study was to determinate the effect of a lower dose of fish oil supplementation on insulin sensitivity, lipid profile, and muscle metabolism in obese rats.MethodsMonosodium glutamate (MSG) (4 mg/g body weight) was injected in neonatal Wistar male rats. Three-month-old rats were divided in normal-weight control group (C), coconut fat-treated normal weight group (CO), fish oil-treated normal weight group (FO), obese control group (Ob), coconut fat-treated obese group (ObCO) and fish oil-treated obese group (ObFO). Obese insulin-resistant rats were supplemented with fish oil or coconut fat (1 g/kg/day) for 4 weeks. Insulin sensitivity, fasting blood biochemicals parameters, and skeletal muscle glucose metabolism were analyzed.ResultsObese animals (Ob) presented higher Index Lee and 2.5 fold epididymal and retroperitoneal adipose tissue than C. Insulin sensitivity test (Kitt) showed that fish oil supplementation was able to maintain insulin sensitivity of obese rats (ObFO) similar to C. There were no changes in glucose and HDL-cholesterol levels amongst groups. Yet, ObFO revealed lower levels of total cholesterol (TC; 30%) and triacylglycerol (TG; 33%) compared to Ob. Finally, since exposed to insulin, ObFO skeletal muscle revealed an increase of 10% in lactate production, 38% in glycogen synthesis and 39% in oxidation of glucose compared to Ob.ConclusionsLow dose of fish oil supplementation (1 g/kg/day) was able to reduce TC and TG levels, in addition to improved systemic and muscle insulin sensitivity. These results lend credence to the benefits of n-3 fatty acids upon the deleterious effects of insulin resistance mechanisms.

Background The effects of docosahexaenoic acid (DHA) on cardiovascular disease are controversial and a mechanistic understanding of how this omega‐3 polyunsaturated fatty acid (ω‐3 PUFA) regulates platelet reactivity and the subsequent risk of a thrombotic event is warranted. In platelets, DHA is oxidized by 12‐lipoxygenase (12‐LOX) producing the oxidized lipids (oxylipins) 11‐HDHA and 14‐HDHA. We hypothesized that 12‐LOX DHA‐oxylipins may be involved in the beneficial effects observed in dietary supplemental treatment with ω‐3 PUFAs or DHA itself. Objectives To determine the effects of DHA, 11‐HDHA, and 14‐HDHA on platelet function and thrombus formation, and to elucidate the mechanism by which these ω‐3 PUFAs regulate platelet activation. Methods and results DHA, 11‐HDHA, and 14‐HDHA attenuated collagen‐induced human platelet aggregation, but only the oxylipins inhibited ⍺IIbβ3 activation and decreased ⍺‐granule secretion. Furthermore, treatment of whole blood with DHA and its oxylipins impaired platelet adhesion and accumulation to a collagen‐coated surface. Interestingly, thrombus formation was only diminished in mice treated with 11‐HDHA or 14‐HDHA, and mouse platelet activation was inhibited following acute treatment with these oxylipins or chronic treatment with DHA, suggesting that under physiologic conditions, the effects of DHA are mediated through its oxylipins. Finally, the protective mechanism of DHA oxylipins was shown to be mediated via activation of protein kinase A. Conclusions This study provides the first mechanistic evidence of how DHA and its 12‐LOX oxylipins inhibit platelet activity and thrombus formation. These findings support the beneficial effects of DHA as therapeutic intervention in atherothrombotic diseases.

Polyunsaturated fatty acids (PUFAs) are structural components of membrane phospholipids in cells. PUFAs regulate cellular function through the formation of derived lipid mediators termed eicosanoids. The oxygenation of 20-carbon PUFAs via the oxygenases cyclooxygenases, lipoxygenases, or cytochrome P450, generates a class of classical eicosanoids including prostaglandins, thromboxanes and leukotrienes, and also the more recently identified hydroxy-, hydroperoxy-, epoxy- and oxo-eicosanoids, and the specialized pro-resolving (lipid) mediators. These eicosanoids play a critical role in the regulation of inflammation in the blood and the vessel. While arachidonic acid-derived eicosanoids are extensively studied due to their pro-inflammatory effects and therefore involvement in the pathogenesis of inflammatory diseases such as atherosclerosis, diabetes mellitus, hypertension, and the coronavirus disease 2019; in recent years, several eicosanoids have been reported to attenuate exacerbated inflammatory responses and participate in the resolution of inflammation. This review focused on elucidating the biosynthesis and the mechanistic signaling of eicosanoids in inflammation, as well as the pro-inflammatory and anti-inflammatory effects of these eicosanoids in the blood and the vascular wall.

Arterial thrombosis is the underlying cause for a number of cardiovascular-related events. Although dietary supplementation that includes polyunsaturated fatty acids (PUFAs) has been proposed to elicit cardiovascular protection, a mechanism for antithrombotic protection has not been well established. The current study sought to investigate whether an omega-6 essential fatty acid, docosapentaenoic acid (DPAn-6), and its oxidized lipid metabolites (oxylipins) provide direct cardiovascular protection through inhibition of platelet reactivity. Human and mouse blood and isolated platelets were treated with DPAn-6 and its 12-lipoxygenase (12-LOX)–derived oxylipins, 11-hydroxy-docosapentaenoic acid and 14-hydroxy-docosapentaenoic acid, to assess their ability to inhibit platelet activation. Pharmacological and genetic approaches were used to elucidate a role for DPA and its oxylipins in preventing platelet activation. DPAn-6 was found to be significantly increased in platelets following fatty acid supplementation, and it potently inhibited platelet activation through its 12-LOX–derived oxylipins. The inhibitory effects were selectively reversed through inhibition of the nuclear receptor peroxisome proliferator activator receptor-α (PPARα). PPARα binding was confirmed using a PPARα transcription reporter assay, as well as PPARα−/− mice. These approaches confirmed that selectivity of platelet inhibition was due to effects of DPA oxylipins acting through PPARα. Mice administered DPAn-6 or its oxylipins exhibited reduced thrombus formation following vessel injury, which was prevented in PPARα−/− mice. Hence, the current study demonstrates that DPAn-6 and its oxylipins potently and effectively inhibit platelet activation and thrombosis following a vascular injury. Platelet function is regulated, in part, through an oxylipin-induced PPARα-dependent manner, suggesting that targeting PPARα may represent an alternative strategy to treat thrombotic-related diseases.

Fish oil (FO) has been shown to affect cancer cachexia, tumor mass, and immunity cell. n-3 PUFA, specifically α-linolenic fatty acid (ALA), has controversial effects. We investigated this in nontumor-bearing Wistar rats fed regular chow (C), fed regular chow and supplemented with FO or Oro Inca oil (OI), and Walker 256 tumor-bearing rats fed regular chow (W), fed regular chow and supplemented with FO (WFO) or OI (WOI). Rats were supplemented (1g/kg body weight/day) during 4 wk and then the groups tumor-bearing were inoculated with Walker 256 tumor cells suspension and 14 days later the animals were killed. WFO increased EPA fivefold and DHA 1.5-fold in the tumor tissue compared to W (P < 0.05). OI supplementation increased of threefold of ALA when compared to W (P < 0.05). Tumor mass in WFO and OI was of 2.3-fold lower, as well as tumor cell proliferation of 3.0-fold tumor tissue lipoperoxidation increased of 76.6% and cox-2 expression was 20% lower. Cachexia parameters were attenuate, blood glucose (25% higher), Triacylglycerolemia (50% lower), and plasma TNF-α (65% lower; P < 0.05) and IL-6 (62.5% lower). OI, rich in ALA, caused the same effect on cancer as those seen in FO.

BackgroundSeveral studies have been shown pro-apoptotic effects of fish oil (FO), rich in n-3 polyunsaturated fatty acids (n-3 PUFA) on cancer cells. Nevertheless, few in vivo experiments have provided data of its ability on apoptosis protein expression in tumor tissue. Thus, in this study we investigate the effect of FO supplementation on apoptosis protein expression in Walker 256 tumor bearing rats. Male Wistar rats were randomly assigned to three groups: fed with regular chow (W); fed regular chow supplemented with FO (WFO) or coconut fat (WCO) (1 g/kg body weight/daily). After thirty days, all animals were inoculated subcutaneously with Walker 256 tumor cells.FindingsProtein expression was done by western blotting in Walker 256 tumor tissue samples. FO decreased the Bcl-2/Bax ratio (p < 0.05) and increased the p53 (p < 0.05), cleaved caspase-7 (p < 0.05) and cleaved caspase-3 (p < 0.05) in Walker 256 tumor tissue.ConclusionsOur data suggest that the pro-apoptotic effect of FO in Walker 256 tumor is related with specifics cleaved caspases.

In this paper, human platelet 12-lipoxygenase [h12-LOX (ALOX12)], human reticulocyte 15-lipoxygenase-1 [h15-LOX-1 (ALOX15)], and human epithelial 15-lipoxygenase-2 [h15-LOX-2 (ALOX15B)] were observed to react with docosahexaenoic acid (DHA) and produce 17S-hydroperoxy-4Z,7Z,10Z,13Z,15E,19Z-docosahexaenoic acid (17S-HpDHA). The k cat/K M values with DHA for h12-LOX, h15-LOX-1, and h15-LOX-2 were 12, 0.35, and 0.43 s–1 μM–1, respectively, which demonstrate h12-LOX as the most efficient of the three. These values are comparable to their counterpart k cat/K M values with arachidonic acid (AA), 14, 0.98, and 0.24 s–1 μM–1, respectively. Comparison of their product profiles with DHA demonstrates that the three LOX isozymes produce 11S-HpDHA, 14S-HpDHA, and 17S-HpDHA, to varying degrees, with 17S-HpDHA being the majority product only for the 15-LOX isozymes. The effective k cat/K M values (k cat/K M × percent product formation) for 17S-HpDHA of the three isozymes indicate that the in vitro value of h12-LOX was 2.8-fold greater than that of h15-LOX-1 and 1.3-fold greater than that of h15-LOX-2. 17S-HpDHA was an effective substrate for h12-LOX and h15-LOX-1, with four products being observed under reducing conditions: protectin DX (PDX), 16S,17S-epoxy-4Z,7Z,10Z,12E,14E,19Z-docosahexaenoic acid (16S,17S-epoxyDHA), the key intermediate in neuroprotection D1 biosynthesis [NPD1, also known as protectin D1 (PD1)], 11,17S-diHDHA, and 16,17S-diHDHA. However, h15-LOX-2 did not react with 17-HpDHA. With respect to their effective k cat/K M values, h12-LOX was markedly less effective than h15-LOX-1 in reacting with 17S-HpDHA, with a 55-fold lower effective k cat/K M in producing 16S,17S-epoxyDHA and a 27-fold lower effective k cat/K M in generating PDX. This is the first direct demonstration of h15-LOX-1 catalyzing this reaction and reveals an in vitro pathway for PDX and NPD1 intermediate biosynthesis. In addition, epoxide formation from 17S-HpDHA and h15-LOX-1 was negatively affected via allosteric regulation by 17S-HpDHA (K d = 5.9 μM), 12S-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12S-HETE) (K d = 2.5 μM), and 17S-hydroxy-13Z,15E,19Z-docosatrienoic acid (17S-HDTA) (K d = 1.4 μM), suggesting a possible regulatory pathway in reducing epoxide formation. Finally, 17S-HpDHA and PDX inhibited platelet aggregation, with EC50 values of approximately 1 and 3 μM, respectively. The in vitro results presented here may help advise in vivo PDX and NPD1 intermediate (i.e., 16S,17S-epoxyDHA) biosynthetic investigations and support the benefits of DHA rich diets.

Lipoxin production requires a hydroperoxide precursor that is dehydrated to form an epoxide. Formation of lipoxin A 4 (LXA 4 ) requires a hydroperoxide at C5, while formation of lipoxin B 4 (LXB 4 ) requires a hydroperoxide at C15. 5S,15S-diHpETE can serve as an intermediate in the biosynthesis of both LXA 4 and LXB 4 because it contains hydroperoxides Perry et al.