Fat Of Mice Research Articles

The effect of omega-3 fatty acids on central nervous system remyelination in fat-1 mice

BackgroundThere is a large body of experimental evidence suggesting that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) are capable of modulating immune function. Some studies have shown that these PUFAs might have a beneficial effect in patients suffering form multiple sclerosis (MS), a chronic inflammatory demyelinating disease of the central nervous system (CNS). This could be due to increased n-3 PUFA-derived anti-inflammatory lipid mediators. In the present study we tested the effect of an endogenously increased n-3 PUFA status on cuprizone-induced CNS demyelination and remyelination in fat-1 mice versus their wild-type (wt) littermates. Fat-1 mice express an n-3 desaturase, which allows them to convert n-6 PUFAs into n-3 PUFAs.ResultsCNS lipid profiles in fat-1 mice showed a significant increase of eicosapentaenoic acid (EPA) levels but similar docosahexaenoic acid levels compared to wt littermates. This was also reflected in significantly higher levels of monohydroxy EPA metabolites such as 18-hydroxyeicosapentaenoic acid (18-HEPE) in fat-1 brain tissue. Feeding fat-1 mice and wt littermates 0.2% cuprizone for 5 weeks caused a similar degree of CNS demyelination in both groups; remyelination was increased in the fat-1 group after a recovery period of 2 weeks. However, at p = 0.07 this difference missed statistical significance.ConclusionsThese results indicate that n-3 PUFAs might have a role in promotion of remyelination after toxic injury to CNS oligodendrocytes. This might occur either via modulation of the immune system or via a direct effect on oligodendrocytes or neurons through EPA-derived lipid metabolites such as 18-HEPE.

Deleterious effect of n-3 polyunsaturated fatty acids in non-alcoholic steatohepatitis in the fat-1 mouse model

Summary Non-alcoholic fatty liver disease (NAFLD) represents a spectrum of pathologies, ranging from hepatocellular steatosis to non-alcoholic steatohepatitis (NASH), fibrosis and cirrhosis. It has been suggested that fish oil containing n-3 polyunsaturated fatty acids (n-3 PUFA) induce beneficial effects in NAFLD. However, n-3 PUFA are sensitive to peroxidation that generate free radicals and reactive aldehydes. We aimed at determining whether changing the tissue ratio of n-3 to n-6 PUFA may be beneficial or alternatively harmful to the etiology of NAFLD. The transgenic Fat-1 mouse model was used to determine whether n-3 PUFA positively or negatively affect the development of NAFLD. fat-1mice express the fat-1 gene of Caenorhabditis elegans, which encodes an n-3 fatty-acid desaturase that converts n-6 to n-3 fatty acids. Wild-type C57BL/6 mice served as the control group. Both groups of mice were fed methionine and choline deficient (MCD) diet, which induces NASH within 4 weeks. The study shows that NASH developed faster and was more severe in mice from the fat-1 group when compared to control C57BL/6 mice. This was due to enhanced lipid peroxidation of PUFA in the liver of the fat-1 mice as compared to the control group. Results of our mice study suggest that supplementing the diet of individuals who develop or have fatty livers with n-3 PUFA should be carefully considered and if recommended adequate antioxidants should be added to the diet in order to reduce such risk.

Fat-1 mice prevent high-fat plus high-sugar diet-induced non-alcoholic fatty liver disease.

High-fat and high-sugar (HFS) diets have been suggested to play a causal role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). This study aimed to investigate whether fat-1 transgenic mice with a higher tissue content of n-3 polyunsaturated fatty acids (PUFAs) could prevent HFS diet-induced NAFLD, compared with wild-type mice. The fat-1 and wild-type littermates had free access to a 15% fructose solution plus high-fat diet, a 15% glucose solution plus high-fat diet, or a 15% sucrose solution plus high-fat diet, respectively. Caloric intake, weight gain, biochemical parameters, histology, and gene and protein expression levels were measured after 8 weeks of intervention. Liquid intake in glucose- or sucrose-fed mice was about 2-fold compared with that in fructose-fed mice. The wild-type mice given glucose showed the highest total caloric intake and weight gain compared to the other groups. The serum concentrations of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and alanine transaminase (ALT) were significantly lowered in fat-1 groups compared with their paired wild-type groups. Histological analysis showed that the wild-type groups fed the HFS diets developed hepatic lipid accumulation and steatosis, compared with the fat-1 groups. The gene and protein expression levels involved in fatty acid synthesis and the toll-like receptor (TLR)-4 signaling pathway were significantly inhibited in the fat-1 groups compared with the wild-type groups. The endogenously synthesized n-3 PUFAs of the three fat-1 groups, which inhibit fatty acid synthesis and the TLR-4 signaling pathway, prevent HFS diet-induced NAFLD.

Endogenously synthesized n-3 polyunsaturated fatty acids in fat-1 transgenic mice suppress B16F10 melanoma lung metastasis by impairing mesenchymal to epithelial transition

Malignant melanoma is an aggressive cancer of neuroectodermal origin. The mechanisms of n-3 polyunsaturated fatty acids (PUFAs) against melanoma metastasis are not clear. Here fat-1 and wild type (WT) mice were injected with B16F10 melanoma cells via the tail vein to establish lung metastasis model. Endogenous n-3 PUFAs were associated with a reduction in grossly visible pulmonary metastases and outgrowth through inhibition of mesenchymal to epithelial transition (MET), which was characterized by decreased expression of epithelial markers E-cadherin and ZO-1, and increased expression of mesenchymal marker vimentin in tumour tissues from fat-1 mice compared with WT controls. In addition, n-3 PUFA-mediated inhibition of MET may have been associated, in part, with the: (i) formation of n-3 PUFA-derived lipid mediators and (ii) decreased expression of mature IL-1β and p-NF-κB, and enhanced expression of superoxide dismutase-1. These results suggest that n-3 PUFAs exert their antitumourigenic activities, in part, via their anti-inflammatory properties.

Brain omega-3 polyunsaturated fatty acids modulate microglia cell number and morphology in response to intracerebroventricular amyloid-β 1-40 in mice.

BackgroundNeuroinflammation is a proposed mechanism by which Alzheimer’s disease (AD) pathology potentiates neuronal death and cognitive decline. Consumption of omega-3 polyunsaturated fatty acids (PUFA) is associated with a decreased risk of AD in human observational studies and exerts protective effects on cognition and pathology in animal models. These fatty acids and molecules derived from them are known to have anti-inflammatory and pro-resolving properties, presenting a potential mechanism for these protective effects.MethodsHere, we explore this mechanism using fat-1 transgenic mice and their wild type littermates weaned onto either a fish oil diet (high in n-3 PUFA) or a safflower oil diet (negligible n-3 PUFA). The fat-1 mouse carries a transgene that enables it to convert omega-6 to omega-3 PUFA. At 12 weeks of age, mice underwent intracerebroventricular (icv) infusion of amyloid-β 1-40. Brains were collected between 1 and 28 days post-icv, and hippocampal microglia, astrocytes, and degenerating neurons were quantified by immunohistochemistry with epifluorescence microscopy, while microglia morphology was assessed with confocal microscopy and skeleton analysis.ResultsFat-1 mice fed with the safflower oil diet and wild type mice fed with the fish oil diet had higher brain DHA in comparison with the wild type mice fed with the safflower oil diet. Relative to the wild type mice fed with the safflower oil diet, fat-1 mice exhibited a lower peak in the number of labelled microglia, wild type mice fed with fish oil had fewer degenerating neurons, and both exhibited alterations in microglia morphology at 10 days post-surgery. There were no differences in astrocyte number at any time point and no differences in the time course of microglia or astrocyte activation following infusion of amyloid-β 1-40.ConclusionsIncreasing brain DHA, through either dietary or transgenic means, decreases some elements of the inflammatory response to amyloid-β in a mouse model of AD. This supports the hypothesis that omega-3 PUFA may be protective against AD by modulating the immune response to amyloid-β.

Enriched endogenous n-3 polyunsaturated fatty acids alleviate cognitive and behavioral deficits in a mice model of Alzheimer’s disease

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder that accompanied by memory deficits and neuropsychiatric dysfunction. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have seemly therapeutic potential in AD, but the benefit of n-3 PUFAs is still in debates. Here, we employed a transgenic mice carry fat-1 gene to encode n-3 desaturase from Caenorhabditis elegans, which increase endogenous n-3 PUFAs by converting n-6 PUFAs to n-3 PUFAs crossed with amyloid precursor protein (APP) Tg mice to evaluate the protective effects of endogenous n-3 PUFAs on cognitive and behavioral deficits of APP Tg mice. We fed APP, APP/fat-1 and fat-1 mice with n-6 PUFAs rich diet. Brain tissues were collected at 3, 9 and 12 months for fatty acid and gene expression analysis, histology and protein assays. Morris Water Maze Test, open field test and elevated plus maze test were performed to measure the behavior capability. From the results, the expression of fat-1 transgene increased cortical n-3: n-6 PUFAs ratio and n-3 PUFAs concentrations, and sensorimotor dysfunction and cognitive deficits in AD were significantly less severe in APP/fat-1 mice with endogenous n-3 PUFAs than in APP mice controls. The protection against disturbance of spontaneous motor activity and cognitive deficits in AD was strongly correlated with increased n-3: n-6 PUFAs ratio and endogenous n-3 PUFAs, reduced APP generation, inhibited amyloid β peptide aggregation, suppressed nuclear factor-kappa B and astroglia activation, and reduced death of neurons in the cortex of APP/fat-1 mice compared with APP mice controls. In conclusion, our study demonstrates that an available medication with the maintenance of enriched n-3 PUFAs in the brain could slow down cognitive decline and prevent neuropsychological disorder in AD.

Abstract LB-299: Enhanced inhibitory effects on mutant KrasG12D-initiated murine pancreatic carcinoma growth in Fat-1 transgenic mice treated with soluble epoxide hydrolase inhibitor t-AUCB

Abstract Anti-carcinogenic effects of ω-3 polyunsaturated fatty acid (PUFAs) are well known; but the mechanism/s remains unclear. Of the three metabolic pathways (COX, LOX, and CYP), ω-3 PUFAs are predominantly metabolized by cyto-p450 epoxygenase/s, leading to an accumulation of ω-3 epoxy fatty acid (ω-3 epoxides), and ω-3 PUFAs are poor substrates of COX and LOX. Functional studies indicate that ω-3 epoxides are highly potential metabolites responsible for anti-inflammatory/carcinogenic actions. However, under physiologic conditions, these ω-3 epoxides are quickly inactivated by soluble epoxide hydrolase (sEH) to the diol products, and a sEH inhibitor appears crucial to stabilizing/enhancing the actions of these ω-3 epoxides. Fat1 transgenic mouse constitutively converts ω-6 to ω-3 PUFAs in all organs and are an efficient model to study ω-3 PUFAs. Herein, we have determined if a potent sEH inhibitor t-AUCB enhanced the inhibitory effect on mutant KrasG12D-initiated pancreatic cancer growth in Fat-1 mice and further determined the metabolic profile of ω-3 PUFAs, particularly on epoxide metabolites. Using an implanted mouse pancreatic carcinoma model (PK03 cell line, obtained from LSL-KrasG12D/Pdx1-Cre mice), a significant reduction of in vivo implanted PK03 pancreatic carcinoma growth was observed in Fat1 mice compared to wild type mice (Tumor volume: 355 ± 50 vs 519 ± 61 mm3, P<0.05), and with t-AUCB treatment the most significant reduction of tumor volume was observed (Tumor volume: 279 ± 35 vs 519 ± 61 mm3, P<0.01), but no difference for tumor volume in wild type mice with or without t-AUCB treatment (522 ± 70 vs 519 ± 61 mm3). Using LC-MS/MS metabolomics approach, modulation of the full oxylipin profile, particularly increased ratio of epoxide metabolites/its corresponded diols for ω-3 PUFAs, was observed in Fat1 mice treated with t-AUCB. Western blot and immunohistochemistry analysis revealed a significant down-regulation of Kras-activated phosphorylated-form C-Raf, MEK and Erk, as well as an up-regulation of E-cadherin; and immunohistochemistry study further demonstrated that ki-67 labeled cell proliferation and myeloperoxidase-labeled inflammatory cells (neutrophils/macrophages) were significantly reduced and Caspase-3 labeled cell apoptosis was significantly increased in pancreatic carcinoma in Fat-1 mice treated with t-AUCB. These results indicate that sEH inhibitor t-AUCB combined with ω-3 PUFAs is a highly potential and efficient approach to treat and prevent pancreatic cancer, particularly via stabilizing ω-3 epoxides. (Supported by NIH R01CA164041 and R01CA172431) Citation Format: Jie Liao, Rong Xia, Jun Yang, Haonan Li, Dandan Xu, Xueyan Wang, Xiaoming You, Sung Hee Hwang, Bruce Hammock, Guang-Yu Yang. Enhanced inhibitory effects on mutant KrasG12D-initiated murine pancreatic carcinoma growth in Fat-1 transgenic mice treated with soluble epoxide hydrolase inhibitor t-AUCB. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-299.

Abstract 834: Constitutive omega-3 fatty acid production in fat-1 transgenic mice protects against UVB-induced skin inflammation and carcinogenesis

Abstract Exposure to solar radiation, especially ultraviolet B (UVB), is the most prevalent cause of skin photocarcinogenesis. Omega-6 (ù-6) and omega-3 (ù-3) polyunsaturated fatty acids (PUFAs) are known to have opposite effects on the inflammatory and carcinogenesis processes. Generally, ù-6 PUFAs promote inflammation and tumor development, whereas ù-3 PUFAs possess anti-inflammatory as well as antioxidative activity and enhance host immune response. In the present study, we investigated the protective effects of ù-3 PUFAs on UVB-induced skin inflammation and carcinogenesis using fat-1 transgenic mice harboring ù-3 desaturase gene capable of converting ù-6 to ù-3 PUFAs. The ù-3/ù-6 PUFA ratio was significantly higher in the dorsal skin of fat-1 mice than that in the wild-type (WT) C57BL/6 mice. In comparison to WT animals, fat-1 mice expressed heme oxygenase-1 and NAD(P)H:quinone oxidoreductase-1 and their mRNA transcripts to a greater extent, which was attributable to the elevated activation of nuclear factor erythroid-related factor-2 (Nrf2) responsible for upregulation of cytoprotective and stress-responsive proteins. Upon single exposure to UVB (500 mJ/cm2) irradiation, fat­1 mice exhibited a significantly lower degree of skin inflammation and phototoxicity and the expression of the pro-inflammatory enzyme, cyclooxygenases-2 (COX-2) as compared to those observed in WT mouse skin. The protection of fat-1 mice from UVB-induced skin inflammation was associated with decreased phosphorylation of signal transducer and activator of transcription 3 (STAT3), one of the major redox-sensitive transcription factors, whose overactivation is implicated in the pathogenesis of inflammation and subsequent development of skin cancer. To determine whether the elevated ù-3 PUFA level also protects against skin papillomagenesis, hairless fat-1−/− albino and fat-1+/− albino mice were generated by cross-breeding of male fat-1+/− transgenic mice with female SKH-1 hairless albino mice. After repeated UVB irradiation (180 mJ/cm2) thrice a week for 23 weeks, the incidence and the multiplicity of papillomas were markedly reduced in the fat-1+/− albino group as compared to the fat-1−/− albino group. Moreover, the expression of COX-2 and activation of STAT3 in papillomas from fat-1+/− albino mice were significantly lower than those found in UVB-irradiated fat-1−/− albino mice. Taken together, our results indicate that functional fat-1 potentiates cellular defense against UVB-induced skin inflammation and tumor development through elevation of Nrf2-mediated upregulation of cytoprotective gene expression. Citation Format: Hye-Won Yum, Joydeb Kumar Kundu, Yong-Yeon Cho, Young-Joon Surh. Constitutive omega-3 fatty acid production in fat-1 transgenic mice protects against UVB-induced skin inflammation and carcinogenesis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 834.

Abstract 4314: Using antioxidant to enhance liver cancer preventive effect of n-3 PUFAs

Abstract In various animal models, n-3 polyunsaturated fatty acids (PUFAs) have demonstrated cancer preventive effects. This protective effect is associated with reduced levels of inflammatory cytokines, such as tumor necrosis factor alpha (TNF-α), cyclooxygenase 2 (COX-2) and prostaglandin E2 (PGE2). On the other hand, an endogenous DNA adduct formed from the peroxidation of ω-3 PUFAs, γ-hydroxy-1, N2-propanodeoxyguanosine (γ-OHPdG), is known to be mutagenic. In light of these observations, we hypothesized that the combination of n-3 PUFAs with an antioxidant to inhibit lipid peroxidation (e.g. α-lipoic acid) will result in an enhanced cancer preventive effect than n-3 PUFAs alone. The chemical carcinogen diethylnitrosamine (DEN) induced HCC model is employed in this study. The DEN-induced HCC model has a histology and genetic signature similar to that of human HCCs, such that it has poor prognosis and recapitulates a dependence on inflammatory signaling. It also reflects the same gender disparity seen in human HCCs. Fat-1 transgenic mice were used because they express a Caenorhabditis elegans desaturase converting n-6 to n-3 PUFAs endogenously without using dietary supplementation. This model underlies the importance of dietary control of PUFAs intake and ratios due to the inability of mammalian cells to generate anti-inflammatory n-3 PUFAs from pro-inflammatory n-6 PUFAs, which are a major component of the standard Western diets. The results showed that antioxidant can efficiently suppress the elevated level of γ-OHPdG in fat-1 mice. The tumor incidence, multiplicity, and size are monitored continuously. This work was supported by the NCI grant: RO1-CA-134892. Y.F. thanks the Prevent Cancer Foundation for his fellowship (Marcia and Frank Carlucci Charitable Foundation Award in Cancer Prevention and Early Detection) Citation Format: Ying Fu, Angela Y. Bai, Marcin Dyba, Jing X. Kang, Fung-Lung Chung. Using antioxidant to enhance liver cancer preventive effect of n-3 PUFAs. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4314.

Abstract 1301: Anti-invasive and antimetastatic effects of ω3-polyunsaturated fatty acids through inhibition of NF-kB/matrix metalloproteinases in ovarian cancer cells

Abstract Ovarian cancer is leading cause of gene cological cancer death in the United States. It is reported that about 14,000 patients will die to ovarian cancer in United States, 2015. ω3- and ω6-PUFAs are considered as essential fatty acids because they cannot be synthesized in mammals. The ω3-desaturase (fat-1) converts ω6-PUFAs to ω3-PUFAs. Cancer cells and transgenic mice stably expressing fat-1 geneare useful models to study the anti-cancer effects of ω3-PUFAs. Here, we show anti-invasive and anti-metastatic action of ω3-PUFA in ovarian cancer.DHA significantly inhibited cell invasion and wound healing activity of human ovarian PA-1 cells. DHA also abolishedthe induction of matrix-metalloproteinases (MMPs) and cyclooxygenase (COX2) as well as the transactivity of NF-κB in PA-1 cells. When ID8 cells were subcutaneously implanted into fat-1 transgenic mice, the tumor size and volume were smallin comparison to wild-type mice. The growth inhibition of tumor was also confirmed with the increase in the level of TUNEL-positive cells. Additionally, when ID8 cells were injected via tail vein of fat1 mice, the lung metastasis was remarkably inhibited in fat-1 transgenic mice. Furthermore, the proliferation of fat-1-stably expressing PA-1 (f-PA-1) cells was more attenuated than that of cells expressing control vectors. The invasion and NF-κB/MMPs promoter activities were also decreased in f-PA-1 cells. These results suggest that ω3-PUFAs inhibit invasion and metastasis of ovarian cancer cells through inhibition of NF-κB/MMPs. Therefore, ω3-PUFAs may contribute an effective and safe therapeutic approach for the chemoprevention and treatment of human ovarian cancer. [This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (2007-0054932)] Citation Format: Soyeon Jeong, Kaipeng Jing, Soyeon Shin, Soyeon Kim, Young-Joo Jeon, Jun-Young Heo, Gi-Ryang Kweon, Seung-Kiel Park, Jong-Il Park, Kyu Lim. Anti-invasive and antimetastatic effects of ω3-polyunsaturated fatty acids through inhibition of NF-kB/matrix metalloproteinases in ovarian cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1301.

Enhanced M2 macrophage polarization in high n-3 polyunsaturated fatty acid transgenic mice fed a high-fat diet.

Diet-induced obesity and consequent insulin resistance are caused, in part, by macrophage polarization and accumulation in peripheral tissues. Here, we examined the effects of endogenously synthesized n-3 PUFAs on macrophage chemotaxis and polarization. Fat-1 mice and wild-type (WT) littermates were fed a 60% calorie high-fat diet (HFD) for 10 weeks. Bone marrow macrophages (BMMs) from fat-1 and WT mice were used in in vitro chemotaxis assays and macrophage polarization studies. WT mice fed a HFD exhibited glucose intolerance, insulin resistance, and lipid accumulation and macrophage infiltration in liver and adipose tissue. However, these metabolic and inflammatory phenotypes were not observed in HFD-fed fat-1 mice. In flow cytometric analysis, M1 macrophage infiltration into adipose tissue was markedly attenuated in fat-1 mice. Consistently, results from in vitro experiments indicated that n-3 PUFAs prevented adipocyte conditioned medium-mediated macrophage chemotaxis, stimulated M2 polarization, and suppressed M1 polarization. The inhibition of macrophage migration by n-3 PUFAs was associated with suppression of multiple kinases, such as IκB kinase, AKT, and focal adhesion kinase. Our results indicate that n-3 PUFAs play a crucial role in macrophage polarization and chemotaxis, and thus regulate the development of HFD-induced tissue inflammation and metabolic derangements.

Enriched Endogenous Omega-3 Fatty Acids in Mice Ameliorate Parenchymal Cell Death After Traumatic Brain Injury.

Currently no effective therapies are available for the treatment of traumatic brain injury (TBI). Early intervention that specifically provides neuroprotection is of most importance which profoundly influences the outcome of TBI. In the present study, we adopted a closed-skull mild TBI model to investigate potential roles of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in protecting against TBI. Using two-photon laser scanning microscopy (2PLSM), parenchymal cell death and reactive oxidative species (ROS) expression were directly observed and recorded after TBI through a thinned skull bone window. Fat-1 mice with high endogenous ω-3 PUFAs significantly inhibited ROS expression and attenuated parenchymal cell death after compression injury during the early injury phase. Elevated generation of glutathione (GSH) and neuroprotectin D1 (NPD1) in the parenchyma of fat-1 mice could be the contributor to the beneficial role of ω-3 PUFAs in TBI. The results of the study suggest that ω-3 PUFAs is an effective neuroprotectant as an early pharmacological intervention for TBI and the information derived from this study may help guide dietary advice for those who are susceptible to repetitive mild TBI.

Free Fatty Acid Receptor 4 (GPR120) Stimulates Bone Formation and Suppresses Bone Resorption in the Presence of Elevated n-3 Fatty Acid Levels.

Free fatty acid receptor 4 (FFA4) has been reported to be a receptor for n-3 fatty acids (FAs). Although n-3 FAs are beneficial for bone health, a role of FFA4 in bone metabolism has been rarely investigated. We noted that FFA4 was more abundantly expressed in both mature osteoclasts and osteoblasts than their respective precursors and that it was activated by docosahexaenoic acid. FFA4 knockout (Ffar4(-/-)) and wild-type mice exhibited similar bone masses when fed a normal diet. Because fat-1 transgenic (fat-1(Tg+)) mice endogenously converting n-6 to n-3 FAs contain high n-3 FA levels, we crossed Ffar4(-/-) and fat-1(Tg+) mice over two generations to generate four genotypes of mice littermates: Ffar4(+/+);fat-1(Tg-), Ffar4(+/+);fat-1(Tg+), Ffar4(-/-);fat-1(Tg-), and Ffar4(-/-);fat-1(Tg+). Female and male littermates were included in ovariectomy- and high-fat diet-induced bone loss models, respectively. Female fat-1(Tg+) mice decreased bone loss after ovariectomy both by promoting osteoblastic bone formation and inhibiting osteoclastic bone resorption than their wild-type littermates, only when they had the Ffar4(+/+) background, but not the Ffar4(-/-) background. In a high-fat diet-fed model, male fat-1(Tg+) mice had higher bone mass resulting from stimulated bone formation and reduced bone resorption than their wild-type littermates, only when they had the Ffar4(+/+) background, but not the Ffar4(-/-) background. In vitro studies supported the role of FFA4 as n-3 FA receptor in bone metabolism. In conclusion, FFA4 is a dual-acting factor that increases osteoblastic bone formation and decreases osteoclastic bone resorption, suggesting that it may be an ideal target for modulating metabolic bone diseases.

Early Low-Fat Diet Enriched With Linolenic Acid Reduces Liver Endocannabinoid Tone and Improves Late Glycemic Control After a High-Fat Diet Challenge in Mice.

Evidence suggests that alterations of glucose and lipid homeostasis induced by obesity are associated with the elevation of endocannabinoid tone. The biosynthesis of the two main endocannabinoids, N-arachidonoylethanolamine and 2-arachidonoyl-glycerol, which derive from arachidonic acid, is influenced by dietary fatty acids (FAs). We investigated whether exposure to n-3 FA at a young age may decrease tissue endocannabinoid levels and prevent metabolic disorders induced by a later high-fat diet (HFD) challenge. Three-week-old mice received a 5% lipid diet containing lard, lard plus safflower oil, or lard plus linseed oil for 10 weeks. Then, mice were challenged with a 30% lard diet for 10 additional weeks. A low n-6/n-3 FA ratio in the early diet induces a marked decrease in liver endocannabinoid levels. A similar reduction was observed in transgenic Fat-1 mice, which exhibit high tissue levels of n-3 FA compared with wild-type mice. Hepatic expression of key enzymes involved in carbohydrate and lipid metabolism was concomitantly changed. Interestingly, some gene modifications persisted after HFD challenge and were associated with improved glycemic control. These findings indicate that early dietary interventions based on n-3 FA may represent an alternative strategy to drugs for reducing endocannabinoid tone and improving metabolic parameters in the metabolic syndrome.

Su2050 ω-3 Polyunsaturated Fatty Acids Synthesized in fat-1 Mice attenuated Intestinal Polyposis and Prevented Colitis-Associated Cancer Through Activation of 15-PGDH/IL-18

Su2050 ω-3 Polyunsaturated Fatty Acids Synthesized in fat-1 Mice attenuated Intestinal Polyposis and Prevented Colitis-Associated Cancer Through Activation of 15-PGDH/IL-18

P556. Endogenous conversion of ω-6 to ω-3 polyunsaturated fatty acids in fat-1 mice attenuated intestinal polyposis by either inhibiting COX-2/β-catenin signalling or activating IL-18

P556. Endogenous conversion of ω-6 to ω-3 polyunsaturated fatty acids in fat-1 mice attenuated intestinal polyposis by either inhibiting COX-2/β-catenin signalling or activating IL-18

Omega-3 fatty acids prevent early-life antibiotic exposure-induced gut microbiota dysbiosis and later-life obesity.

Early-life antibiotic exposure can disrupt the founding intestinal microbial community and lead to obesity later in life. Recent studies show that omega-3 fatty acids can reduce body weight gain and chronic inflammation through modulation of the gut microbiota. We hypothesize that increased tissue levels of omega-3 fatty acids may prevent antibiotic-induced alteration of gut microbiota and obesity later in life. Here, we utilize the fat-1 transgenic mouse model, which can endogenously produce omega-3 fatty acids and thereby eliminates confounding factors of diet, to show that elevated tissue levels of omega-3 fatty acids significantly reduce body weight gain and the severity of insulin resistance, fatty liver and dyslipidemia resulting from early-life exposure to azithromycin. These effects were associated with a reversal of antibiotic-induced dysbiosis of gut microbiota in fat-1 mice. These results demonstrate the beneficial effects of omega-3 fatty acids on antibiotic-induced gut dysbiosis and obesity, and suggest the potential utility of omega-3 supplementation as a safe and effective means for the prevention of obesity in children who are exposed to antibiotics.

Protection against Oxygen-Glucose Deprivation/Reperfusion Injury in Cortical Neurons by Combining Omega-3 Polyunsaturated Acid with Lyciumbarbarum Polysaccharide.

Ischemic stroke, characterized by the disturbance of the blood supply to the brain, is a severe worldwide health threat with high mortality and morbidity. However, there is no effective pharmacotherapy for ischemic injury. Currently, combined treatment is highly recommended for this devastating injury. In the present study, we investigated neuroprotective effects of the combination of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and Lyciumbarbarum polysaccharide (LBP) on cortical neurons using an in vitro ischemic model. Our study demonstrated that treatment with docosahexaenoic acid (DHA), a major component of the ω-3 PUFAs family, significantly inhibited the increase of intracellular Ca2+ in cultured wild type (WT) cortical neurons subjected to oxygen-glucose deprivation/reperfusion (OGD/R) injury and promoted their survival compared with the vehicle-treated control. The protective effects were further confirmed in cultured neurons with high endogenous ω-3 PUFAs that were isolated from fat-1 mice, in that a higher survival rate was found in fat-1 neurons compared with wild-type neurons after OGD/R injury. Our study also found that treatment with LBP (50 mg/L) activated Trk-B signaling in cortical neurons and significantly attenuated OGD/R-induced cell apoptosis compared with the control. Notably, both combining LBP treatment with ω-3 PUFAs administration to WT neurons and adding LBP to fat-1 neurons showed enhanced effects on protecting cortical neurons against OGD/R injury via concurrently regulating the intracellular calcium overload and neurotrophic pathway. The results of the study suggest that ω-3 PUFAs and LBP are promising candidates for combined pharmacotherapy for ischemic stroke.

Endogenous n-3 Fatty Acids Alleviate Carbon-Tetrachloride-Induced Acute Liver Injury in Fat-1 Transgenic Mice.

n-3 polyunsaturated fatty acids (PUFAs) are beneficial for numerous models of liver diseases. The probable protective effects of n-3 PUFA against carbon-tetrachloride- (CCl4-) induced acute liver injury were evaluated in a fat-1 transgenic mouse that synthesizes endogenous n-3 from n-6 PUFA. Fat-1 mice and their WT littermates were fed a modified AIN93 diet containing 10% corn oil and were injected intraperitoneally with a single dose of CCl4 or vehicle. CCl4 challenge caused severe liver injury in WT mice, as indicated by serum parameters and histopathological changes, which were remarkably ameliorated in fat-1 mice. Endogenous n-3 PUFA decreased the elevation of oxidative stress induced by CCl4 challenge, which might be attributed to the activation of Nrf2/keap1 pathway. Additionally, endogenous n-3 PUFA reduces hepatocyte apoptosis via suppressing MAPK pathway. These findings indicate that n-3 PUFA has potent protective effects against acute liver injury induced by CCl4 in mice, suggesting that n-3 PUFA can be used for the prevention and treatment of liver injury.

Fat-1 Transgenic Mice: An Endogenous N-3 Polyunsaturated Fatty Acids Mouse Model is used in AD Research

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have been wildly considered for positive effect of Alzheimer’s disease (AD). However, the intake of n-3 PUFAs is not encouraging to draw firm conclusion through preclinical and clinical research. The contribution of debate is derived from interference of dietary n-3 PUFAs, because of controlling the components and ratio of dietary PUFAs difficultly. In this context, transgenic fat-1 mouse that is capable of converting n-6 to n-3 fatty acids by feeding high n-6 PUFAs diet, leading to balance high n-3/n-6 PUFAs ratio, with increasing endogenous n-3 PUFAs and decreasing n-6 PUFAs in their organs and tissues. Thus, fat-1 mice is an ideal model to study the efficacy and mechanism of n-3 PUFAs in AD research, without the interference of the inevitable factors from dietary n-3 PUFAs. The fat-1 transgenic mice have become a useful tool for studying the potential benefit of endogenous n-3 PUFAs in behavior and neuromechanism of AD.