Zingiberene exerts chemopreventive activity against 7,12-dimethylbenz(a)anthracene-induced breast cancer in Sprague-Dawley rats.

Breast cancer is the primary cause of cancer-related death in females, wherein increased mortality of breast cancer patients is recorded worldwide. Zingiberene is a monocyclic sesquiterpene from the ginger plant and has many pharmacological benefits. In this exploration, we assessed the anticancer actions of Zingiberene against the 7,12-dimethylbenz(a)anthracene (DMBA)-stimulated mammary carcinogenesis in rats and MDA-MB-231 cells. Breast cancer was induced in the Female Sprague-Dawley rats through the 25 mg/kg of DMBA in 0.5 ml of corn oil and then treated with 20 and 40 mg/kg of Zingiberene, respectively. The body weight of animals and tumor volume was measured. Hematological parameters, transaminases, lipid profile, lipid peroxidation, and antioxidants status were scrutinized using standard techniques. The estrogen receptor-α and inflammatory markers were inspected by using respective assay kits. Histological damage scores were determined. In vitro experiments were conducted to scrutinize Zingiberene's effect on cell viability and apoptotic cell death in MDA-MB-231 cells. Zingiberene substantially modulated the DMBA-stimulated physiological and hematological changes and decreased the transaminases, and lipid peroxidation in the DMBA-stimulated animals. Zingiberene also elevated the antioxidant level and suppressed the inflammatory markers. Histological study revealed the protective effects of Zingiberene. The viability of MDA-MB-231 cells was noticeably diminished by the Zingiberene, thus inducing apoptotic cell death. Overall, our findings reliably proved the anticancer potential of Zingiberene against the DMBA-stimulated mammary tumorigenesis, and it could be a promising chemotherapeutic agent.

Intraperitoneal Oil Application Causes Local Inflammation with Depletion of Resident Peritoneal Macrophages.

Oil is frequently used as a solvent to inject lipophilic substances into the peritoneum of laboratory animals. Although mineral oil causes chronic peritoneal inflammation, little is known whether other oils are better suited. We show that olive, peanut, corn, or mineral oil causes xanthogranulomatous inflammation with depletion of resident peritoneal macrophages. However, there were striking differences in the severity of the inflammatory response. Peanut and mineral oil caused severe chronic inflammation with persistent neutrophil and monocyte recruitment, expansion of the vasculature, and fibrosis. Corn and olive oil provoked no or only mild signs of chronic inflammation. Mechanistically, the vegetal oils were taken up by macrophages leading to foam cell formation and induction of cell death. Olive oil triggered caspase-3 cleavage and apoptosis, which facilitate the resolution of inflammation. Peanut oil and, to a lesser degree, corn oil, triggered caspase-1 activation and macrophage pyroptosis, which impair the resolution of inflammation. As such, intraperitoneal oil administration can interfere with the outcome of subsequent experiments. As a proof of principle, intraperitoneal peanut oil injection was compared with its oral delivery in a thioglycolate-induced peritonitis model. The chronic peritoneal inflammation due to peanut oil injection impeded the proper recruitment of macrophages and the resolution of inflammation in this peritonitis model. In summary, the data indicate that it is advisable to deliver lipophilic substances, like tamoxifen, by oral gavage instead of intraperitoneal injection. IMPLICATIONS: This work contributes to the reproducibility of animal research by helping to understand some of the undesired effects observed in animal experiments.

A high-fat diet rich in corn oil exaggerates the infarct size and memory impairment in rats with cerebral ischemia and is associated with suppressing osteopontin and Akt, and activating GS3Kß, iNOS, and NF-κB.

The increase in osteopontin (OPN) levels after stroke induces neural protection by activating Akt signaling and inhibiting GS3Kß, iNOS, and NF-κB. This study investigated the effect of a high-fat diet rich in corn oil (CO-HFD) on infarct size and memory function in rats after induction of cerebral ischemia in rats and investigated its effect on the expression of OPN/Akt/iNOS/NF-κB signaling pathways. Rats were initially fed a standard diet (STD, 3.82 kcal/g; 9.4%, from fat) or a CO-HFD (5.4 kcal/g, 40% from fat) for 12 weeks. Then, both groups were further subdivided into either sham group or group exposed to cerebral ischemia by the middle cerebral artery occlusion (MCAO) protocol. Compared with sham-operated rats fed STD diet, neurological scores and both short- and long-term memory functions were significantly impaired in sham-operated CO-HFD-fed rats. In addition, brains collected from CO-HFD-fed rats showed lower protein levels of OPN, p-Akt (Thr308), p-GS3Kß (Ser9), and Bcl-2 and had higher protein levels of iNOS, cleaved caspase-3, nuclear NF-κB p65, and cytoplasmic cytochrome C. However, once exposed to MCAO surgery, similar but more profound alterations of all these biochemical parameters with more severe impairment in short- and long-term memory functions and larger infarct size were noticed in the brains of CO-HFD-fed rats as compared with STD-fed rats exposed to MCAO. In conclusion, chronic consumption of CO-HFD induces memory impairments and worsens memory function recovery and infarct size after cerebral ischemia in rats by reducing levels of OPN, inhibiting the activation of Akt and activating iNOS and NF-κB.

Resolvin D1 Prevents the Impairment in the Retention Memory and Hippocampal Damage in Rats Fed a Corn Oil-Based High Fat Diet by Upregulation of Nrf2 and Downregulation and Inactivation of p66Shc.

This study investigated the effect of a high-fat diet rich in corn oil (CO-HFD) on the memory retention and hippocampal oxidative stress, inflammation, and apoptosis in rats, and examined if the underlying mechanisms involve modulating Resolvin D1 (RvD1) levels and activation of p66Shc. Also, we tested if co-administration of RvD1 could prevent these neural adverse effects induced by CO-HFD. Adult male Wistar rats were divided into 4 groups (n = 18/each) as control fed standard diet (STD) (3.82 kcal/g), STD + RvD1 (0.2 µg/Kg, i.p/twice/week), CO-HFD (5.4 kcal/g), and CO-HFD + RvD1. All treatments were conducted for 8 weeks. With normal fasting glucose levels, CO-HFD induced hyperlipidemia, hyperinsulinemia, increased HOMA-IRI and reduced the rats' memory retention. In parallel, CO-HFD increased levels of reactive oxygen species (ROS), malondialdehyde (MDA), cytoplasmic cytochrome-c, and cleaved caspase-3 and significantly decreased levels of glutathione (GSH), Bcl-2, and manganese superoxide dismutase (MnSOD) in rats' hippocampi. Besides, CO-HFD significantly reduced hippocampal levels of docosahexaenoic acid (DHA) and RvD1, as well as total protein levels of Nrf2 and significantly increased nuclear protein levels of p-NF-κB. Concomitantly, CO-HFD increased hippocampal protein levels of p-JNK, p53, p66Shc, p-p66Shc, and NADPH oxidase. However, without altering plasma and serum levels of glucose, insulin, and lipids, co-administration of RvD1 to CO-HFD completely reversed all these events. It also resulted in similar effects in the STD fed-rats. In conclusion, CO-HFD impairs memory function and induces hippocampal damage by reducing levels of RvD1 and activation of JNK/p53/p66Shc/NADPH oxidase, effects that are prevented by co-administration of RvD1.

Chronic consumption of a high-fat diet rich in corn oil activates intrinsic cell death pathway and induces several ultrastructural changes in the atria of healthy and type 1 diabetic rat.

This study investigates the effect of chronic consumption of a high-fat diet rich in corn oil (CO-HFD) on atrial cells ultrastructure, antioxidant levels and markers of intrinsic cell death of both control and type 1 diabetes mellitus (T1DM)-induced rats. Adult male rats (10 rats/group) were divided into four groups: control fed standard diet (STD) (3.82 kcal/g, 9.4% fat), CO-HFD (5.4 kcal/g, 40% fat), T1DM fed STD, and T1DM + CO-HFD. CO-HFD and T1DM alone or in combination impaired systolic and diastolic functions of rats and significantly reduced levels of GSH and the activity of SOD, enhanced lipid peroxidation, increased protein levels of P53, Bax, cleaved caspase-3, and ANF and decreased levels of Bcl-2 in their atria. Concomitantly, atrial cells exhibited fragmentation of the myofibrils, disorganized mitochondria, decreased number of atrionatriuretic factor (ANF) granules, and loss of gap junctions accompanied by changes in capillary walls. Among all treatments, the severity of all these findings was more severe in T1DM and most profound in the atria of T1DM + CO-HFD. In conclusion, chronic consumption of CO-HFD by T1DM-induced rats elicits significant biochemical and ultrastructural damage to rat atrial cells accompanied by elevated oxidative stress and mitochondria-mediated cell death.

A high-fat diet rich in corn oil induces cardiac fibrosis in rats by activating JAK2/STAT3 and subsequent activation of ANG II/TGF-1ß/Smad3 pathway: The role of ROS and IL-6 trans-signaling.

This study compared the effect of low-fat diet (LFD) and high-fat diet rich in corn oil (HFD-CO) on left ventricular (LV) fibrosis in rats and examined their effect of angiotensin II (ANG II), JAK/STAT, and TGF-1ß/smad3 pathways. As compared to LFD which didn't affect any of the measured parameters, HFD-CO-induced type 2 diabetes phenotype and increased LV collagen synthesis. Mechanistically, it increased LV levels of ROS, ANG II, ACE, IL-6, s-IL-6Rα, TGF-ß1, Smad-3, and activities of JAK1/2 and STAT1/3. AG490, a JAK2 inhibitor, partially ameliorated these effect while Losartan, an AT1 inhibitor completely abolished collagen synthesis. However, with both treatments, levels of ANG II, IL-6, and s-IL-6Rα, and activity of JAK1/STAT3 remained high, all of which were normalized by co-administration of NAC or IL-6 neutralizing antibody. In conclusion: HFD-CO enhances LV collage synthesis by activation of JAK1/STAT3/ANG II/TGF-1ß/smad3 pathway. PRACTICAL APPLICATIONS: We report that chronic consumption of a high-fat diet rich in corn oil (HFD-CO) induces diabetes mellitus phenotype 2 associated with left ventricular (LV) cardiac fibrosis in rats. The findings of this study show that HFD-CO, and through the increasing generation of ROS and IL-6 levels and shedding, could activate LV JAK1/2-STAT1/3  and  renin-angiotensin system (RAS) signaling pathways, thus creating a positive feedback between the two which ultimately leads to activation of TGF-1ß/Smad3 fibrotic pathway. Herein, we also report a beneficial effect of the antioxidant, NAC, or IL-6 neutralizing antibody in preventing such adverse effects of such HFD-CO. However, this presents a warning message to the current sudden increase in idiopathic cardiac disorders, especially with the big shift in our diets toward n-6 PUFA.

Fas/FasL-mediated cell death in rat's diabetic hearts involves activation of calcineurin/NFAT4 and is potentiated by a high-fat diet rich in corn oil.

This study investigated if calcineurin/nuclear factor of activated T cells (NFAT) axis mediates the cardiac apoptosis in rats with type 1 diabetes mellitus (T1DM)-induced rats or administered chronically high-fat diet rich in corn oil (CO-HFD). Also, it investigated the impact of chronic administration of CO-HFD on Fas/Fas ligand (Fas/FasL)-induced apoptosis in the hearts of T1DM-induced rats. Adult male Wistar rats (140-160 g) were classified as control: (10% fat) CO-HFD: (40% fat), T1DM, and T1DM + CO-HFD (n=20/each). In vitro, cardiomyocytes were cultured in either low glucose (LG) or high glucose (HG) media in the presence or absence of linoleic acid (LA) and other inhibitors. Compared to the control, increased reactive oxygen species (ROS), protein levels of cytochrome C, cleaved caspase-8 and caspase-3, myocardial damage and impeded left ventricular (LV) function were observed in the hearts of all treated groups and maximally in T1DM + CO-HFD-treated rats. mRNA of all NFAT members (NFAT1-4) were not affected by any treatment. CO-HFD or LA significantly up-regulated Fas levels in both LVs and cultured cardiomyocytes in a ROS dependent mechanism and independent of modulating intracellular Ca2+ levels or calcineurin activity. T1DM or hyperglycemia significant up-regulated mRNA and protein levels of Fas and FasL by activating Ca2+/calcineurin/NFAT-4 axis. Furthermore, Fas/FasL cell death induced by recombinant FasL (rFasL) or HG media was enhanced by pre-incubating the cells with LA. In conclusion, activation of the Ca2+/calcineurin/NFAT4 axis is indispensable for hyperglycemia-induced Fas/FasL cell death in the cardiomyocytes and CO-HFD sensitizes this by up-regulation of Fas.

A high-corn-oil diet strongly stimulates mammary carcinogenesis, while a high-extra-virgin-olive-oil diet has a weak effect, through changes in metabolism, immune system function and proliferation/apoptosis pathways.

Breast cancer is the most common malignancy in women worldwide, and dietary lipids are important environmental factors influencing its etiology. We have investigated the effects, and the mechanisms associated, of high-fat diets on 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors. Animals were fed a low-fat, a high-corn-oil (HCO) or a high-extra-virgin-olive-oil (HOO) diet from weaning or after induction. The HCO diet had a clear stimulating effect on mammary carcinogenesis, especially when dietary intervention started after induction, whereas the tumors from HOO diet groups exhibited clinical and morphological characteristics similar to those from low-fat controls. Transcriptomic and further protein and immunohistochemical analyses of tumors also indicated different modulatory effects of high-fat diets affecting relevant biological functions: metabolism, immunosurveillance and proliferation/apoptosis pathways. Thus, the results suggested different metabolic adaptations with increased glycolysis by effect of HOO diet. Moreover, leukocyte tumor infiltration and inflammation mediators showed increased cytotoxic T cells and decreased TGFß1 expression by the HOO diet, while the HCO one increased arginase expression and IL-1α plasma levels. Furthermore, the study of proteins controlling proliferation/apoptosis pathways (Sema3A, Stat5, Smad1, Casp3) suggested an increase in proliferation by the HCO diet and an increase of apoptosis by the diet rich in olive oil. In conclusion, the HCO diet clearly stimulated mammary carcinogenesis, especially in the promotion phase, and induced molecular changes suggesting increased tumor proliferation/apoptosis balance and a proinflammatory microenvironment. The HOO diet, despite being high fat, had a weaker effect on tumorigenesis probably related to metabolic adaptations, enhanced immunosurveillance and increased apoptosis.

Potential Interference of Oil Vehicles on Genital Tubercle Development during the Fetal Period in ICR Mice.

Corn oil, sesame oil, and 10% ethanol in corn oil are commonly used as dosing vehicles in toxicology studies. Since these vegetable oils contain bioactive compounds, it is important for toxicology studies to characterize the toxicities of the dosing vehicles themselves. It has been recently proposed that the width of the genital tubercle (GT), the dorsal-ventral length (D-V length) of the GT, and urethral tube closure in mouse fetuses can be used as novel markers for monitoring sexual development in mice. However, how these parameters are influenced by the dosing vehicles themselves remains unclear. Therefore, we evaluated the effects of corn oil, sesame oil, and 10% ethanol in corn oil on GT width, D-V length, and GT morphology in ICR mice. Our results showed that all three vehicles influenced GT width and D-V length, but not GT morphology, suggesting that the effects of dosing vehicles themselves might need to be considered when GT width or D-V length is used as a parameter to evaluate the effects of chemicals on GT development.

Effects of Repeated Intraperitoneal Injection of Pharmaceutical-grade and Nonpharmaceutical-grade Corn Oil in Female C57BL/6J Mice.

Due to potential adverse effects on animal wellbeing, the use of nonpharmaceutical-grade substances in animal research must be scientifically justified in cases where a pharmaceutical-grade version of the substance exists. This requirement applies to all substances, including vehicles used to solubilize experimental drugs. To date, no studies have evaluated the direct effect of the pharmaceutical classification of a compound on animal wellbeing. In this study, we evaluated intraperitoneal administration of pharmaceutical-grade corn oil, nonpharmaceutical-grade corn oil, and saline in female C57BL/6J mice. Compounds were administered every 48 h for a total of 4 injections. Mice were evaluated clinically by using body weight, body condition score, visual assessment score, CBC, and serum chemistries. Animals were euthanized at 24 h and 14 d after the final injection. Inflammation of the peritoneal wall and mesenteric fat was assessed microscopically by using a semiquantitative scoring system. Saline-dosed groups had lower pathology scores at both time points. At day 21, pharmaceutical-grade corn oil had a significantly higher pathology score compared with nonpharmaceutical-grade corn oil. No other significant differences between the corn oil groups were observed. The use of nonpharmaceutical grade corn oil did not result in adverse clinical consequences and is presumed safe to use for intraperitoneal injection in mice. Differences in inflammation between the 2 groups suggest that the use of either pharmaceutical-grade or nonpharmaceutical-grade corn oil should be consistent within a study.

Lipidomic and Antioxidant Response to Grape Seed, Corn and Coconut Oils in Healthy Wistar Rats.

Specialty oils differ in fatty acid, phytosterol and antioxidant content, impacting their benefits for cardiovascular health. The lipid (fatty acid, phytosterol) and antioxidant (total phenolics, radical scavenging capacity) profiles of grapeseed (GSO), corn (CO) and coconut (CNO) oils and their physiological (triacylglycerides, total and HDL-cholesterol and antioxidant capacity (FRAP) in serum and fatty acid and phytosterol hepatic deposition) and genomic (HL, LCAT, ApoA-1 and SR-BP1 mRNA hepatic levels) responses after their sub-chronic intake (10% diet for 28 days) was examined in healthy albino rats. Fatty acid, phytosterol and antioxidant profiles differed between oils (p ≤ 0.01). Serum and hepatic triacylglycerides and total cholesterol increased (p ≤ 0.01); serum HDL-Cholesterol decreased (p < 0.05); but serum FRAP did not differ (p > 0.05) in CNO-fed rats as compared to CO or GSO groups. Hepatic phytosterol deposition was higher (+2.2 mg/g; p ≤ 0.001) in CO- than GSO-fed rats, but their fatty acid deposition was similar. All but ApoA-1 mRNA level increased in GSO-fed rats as compared to other groups (p ≤ 0.01). Hepatic fatty acid handling, but not antioxidant response, nor hepatic phytosterol deposition, could be related to a more efficient reverse-cholesterol transport in GSO-fed rats as compared to CO or CNO.

Diets high in corn oil or extra-virgin olive oil differentially modify the gene expression profile of the mammary gland and influence experimental breast cancer susceptibility.

PURPOSE: Nutritional factors, especially dietary lipids, may have a role in the etiology of breast cancer. We aimed to analyze the effects of high-fat diets on the susceptibility of the mammary gland to experimental malignant transformation. METHODS: Female Sprague-Dawley rats were fed a low-fat, high-corn-oil, or high-extra-virgin olive oil (EVOO) diet from weaning or from induction. Animals were induced with 7,12-dimethylbenz[a]anthracene at 53 days and euthanized at 36, 51, 100 and 246 days. Gene expression profiles of mammary glands were determined by microarrays. Further molecular analyses were performed by real-time PCR, TUNEL and immunohistochemistry. Carcinogenesis parameters were determined at 105 and 246 days. RESULTS: High-corn-oil diet increased body weight and mass when administered from weaning. The EVOO diet did not modify these parameters and increased the hepatic expression of UCP2, suggesting a decrease in intake/expenditure balance. Both diets differentially modified the gene expression profile of the mammary gland, especially after short dietary intervention. Corn oil down-regulated the expression of genes related to immune system and apoptosis, whereas EVOO modified the expression of metabolism genes. Further analysis suggested an increase in proliferation and lower apoptosis in the mammary glands by effect of the high-corn-oil diet, which may be one of the mechanisms of its clear stimulating effect on carcinogenesis. CONCLUSIONS: The high-corn-oil diet strongly stimulates mammary tumorigenesis in association with modifications in the expression profile and an increased proliferation/apoptosis balance of the mammary gland.

Migrated phthalate levels into edible oils.

The determination of phthalates in edible oils (virgin olive oil, olive oil, canola oil, hazelnut oil, sunflower oil, corn oil) sold in Turkish markets was carried out using gas chromatography-mass spectrometry. Mean phthalate concentrations were between 0.102 and 3.863 mg L(-1) in virgin olive oil; 0.172 and 6.486 mg L(-1) in olive oil; 0.501 and 3.651 mg L(-1) in hazelnut oil; 0.457 and 3.415 mg L(-1) in canola oil; 2.227 and 6.673 mg L(-1) in sunflower oil; and 1.585 and 6.248 mg L(-1) in corn oil. Furthermore, the influence of the types of oil and container to the phthalate migration was investigated. The highest phthalate levels were measured in sunflower oil. The lowest phthalate levels were determined in virgin olive oil and hazelnut oil. The highest phthalate levels were determined in oil samples contained in polyethylene terephthalate.

A high-fat diet rich in corn oil reduces spontaneous locomotor activity and induces insulin resistance in mice.

Over the last few decades, polyunsaturated fatty acid (PUFA), especially n-6 PUFA, and monounsaturated fatty acid content in 'Western diets' has increased manyfold. Such a dietary shift also parallels rising sedentary behavior and diabetes in the Western world. We queried if a shift in dietary fats could be linked to physical inactivity and insulin insensitivity in mice. Eight-week old female C57/Bl6 mice were fed either high-fat (HF) diets [40% energy corn oil (CO) or isocaloric olive oil (OO) diets] or chow (n=10/group) for 6 weeks, followed by estimation of spontaneous locomotor activity, body composition and in vivo metabolic outcomes. Although lean mass and resting energy expenditure stayed similar in both OO- and CO-fed mice, only CO-fed mice demonstrated reduced spontaneous locomotor activity. Such depressed activity in CO-fed mice was accompanied by a lower respiratory ratio, hyperinsulinemia and impaired glucose disposal following intraperitoneal glucose tolerance and insulin tolerance tests compared to OO-fed mice. Unlike the liver, where both HF diets increased expression of fat oxidation genes like PPARs, the skeletal muscle of CO-fed mice failed to up-regulate such genes, thereby supporting the metabolic insufficiencies observed in these mice. In summary, this study demonstrates a specific contribution of n-6 PUFA-rich oils like CO to the loss of spontaneous physical activity and insulin sensitivity in mice. If these data hold true for humans, this study could provide a novel link between recent increases in dietary n-6 PUFA to sedentary behavior and the development of insulin resistance in the Western world.

Dietary extra-virgin olive oil and corn oil differentially modulate the mRNA expression of xenobiotic-metabolizing enzymes in the liver and in the mammary gland in a rat chemically induced breast cancer model.

High extra-virgin olive oil (EVOO) and corn oil diets differentially modulate experimental mammary carcinogenesis. We have investigated their influence on the initiation stage through the modulation of the expression of xenobiotic-metabolizing enzymes (XMEs) in the liver and the mammary gland. Female Sprague-Dawley rats were fed a low-fat (LF), high corn oil (HCO), or high EVOO (HOO) diet from weaning and gavaged with 7,12-dimethylbenz(a)anthracene (DMBA). The HCO diet increased the mRNA levels of the phase I enzymes CYP1A1, CYP1A2 and, to a lesser extent, CYP1B1, in the liver. The Aryl hydrocarbon receptor (AhR) seemed to be involved in this upregulated CYP1 expression. However, a slight trend toward an increase in the mRNA levels of the phase II enzymes GSTP1 and NQO1 was observed with the HOO diet. At least in the case of GSTP1, this effect was linked to an increased Nrf2 transactivation activity. This different regulation of the XMEs expression led, in the case of the HCO diet, to a balance between the production of active carcinogenic compounds and their inactivation tilted toward phase I, which would stimulate DMBA-induced cancer initiation, whereas the HOO diet was associated with a slower phase I metabolism accompanied by a faster phase II detoxification, thus reducing the output of the active compounds to the target tissues. In the mammary gland, the differential effects of diets may be conditioned by the state of cell differentiation, sexual maturity, and hormone metabolism.

Food-derived peroxidized fatty acids may trigger hepatic inflammation: a novel hypothesis to explain steatohepatitis.

BACKGROUND & AIMS: Obesity and hepatic steatosis are frequently associated with the development of a non-alcoholic steatohepatitis (NASH). The mechanisms driving progression of a non-inflamed steatosis to NASH are largely unknown. Here, we investigated whether ingestion of peroxidized lipids, as being present in Western style diet, triggers the development of hepatic inflammation. METHODS: Corn oil containing peroxidized fatty acids was administered to rats by gavage for 6 days. In a separate approach, hepatocytes (HC), endothelial (EC) and Kupffer cells (KC) were isolated from untreated livers, cultured, and incubated with peroxidized linoleic acid (LOOH; linoleic acid (LH) being the main fatty acid in corn oil). Samples obtained from in vivo and in vitro studies were mainly investigated by qRT-PCR and biochemical determinations of lipid peroxidation products. RESULTS: Rat treatment with peroxidized corn oil resulted in increased hepatic lipid peroxidation, upregulation of nitric oxide synthetase-2 (NOS-2), cyclooxygenase-2 (COX-2), interleukin-1ß (IL-1ß), and tumor necrosis factor-α (TNFα), elevation of total nitric oxides, and increase in cd68-, cd163-, TNFα-, and/or COX-2 positive immune cells in the liver. When investigating liver cell types, LOOH elevated the secretion of TNFα, p38MAPK phosphorylation, and mRNA levels of NOS-2, COX-2, and TNFα, mainly in KC. The elevation of gene expression could be abrogated by inhibiting p38MAPK, which indicates that p38MAPK activation is involved in the pro-inflammatory effects of LOOH. CONCLUSIONS: These data show for the first time that ingestion of peroxidized fatty acids carries a considerable pro-inflammatory stimulus into the body which reaches the liver and may trigger the development of hepatic inflammation.

Effects of trans-fatty acids on liver lipid metabolism in mice fed on diets showing different fatty acid composition.

AIM: Our aim was to investigate the effects of trans-fatty acids (TFA) on liver lipid metabolism in mice fed on experimental diets rich in either oleic or linoleic acid. METHODS: Twenty-two male CF1 mice (22.0 ± 0.1 g) were fed with diets rich in corn oil or olive oil, supplemented or not with TFA (0.75 g TFA/100 g diet), for 4 weeks. Changes in triacylglycerol content, the activity and expression of enzymes involved in lipogenesis and fatty acid oxidation were measured. RESULTS: Supplementation of an olive oil-rich diet with TFA increased liver triacylglycerols, the activity and expression of lipogenic enzymes and sterol regulatory element-binding protein SREBP-1a expression. By contrast, when TFA were added to a corn oil-rich diet, they did not modify these parameters. No significant differences were observed among the experimental groups in the activity and expression of carnitine palmitoyltransferase-Ia, body and liver weights or serum triacylglycerol concentrations. CONCLUSIONS: The effect of TFA on liver fat accumulation depends on the dietary fatty acid composition. Steatosis induced by TFA when included in an olive oil diet (but not in a corn oil diet) was associated with an increased lipogenesis but not with a decreased fatty acid oxidation in animals fed on the olive oil diet. This metabolic change is mediated by SREBP-1a but not by SREBP-1c, and seems to be independent of insulin.

Corn oil as a vehicle in drug development exerts a dose-dependent effect on gene expression profiles in rat thymus.

The purpose of this study was to investigate the effects of corn oil (CO), which is widely used as a vehicle for water-insoluble agents in drug development, on the gene expression profiles in rat thymus with microarray technique. Female Wistar rats were administered daily with normal saline (NS) and CO 2, 5 and 10 ml kg⁻¹ per day for 14 days, respectively. Then, the thymus samples of rats were collected for microarray test and histopathology examination. CD4⁺ and CD8⁺ lymphocytes in peripheral blood were also numerated to assess the effects on lymphocyte subpopulations. The microarray data showed that the numbers of differentially expressed genes in the 2, 5 and 10 ml kg⁻¹ CO groups were 0, 40 and 458, respectively, compared with the NS control group. The altered genes were mainly associated with immune response, cellular response to organic cyclic substance and regulation of fatty acid ß-oxidation. However, no abnormal changes in thymus weight, CD4⁺ and CD8⁺ lymphocytes counts and histopathological examination were observed in the three CO groups. These data showed that 10 ml kg⁻¹ CO, the usually recommended dosing volume as a vehicle in drug safety assessment, caused obvious dysregulated genes in rat thymus. Our study suggests that the appropriate dosing volume of CO gavage as a vehicle for water-insoluble agents in drug development should be 2 ml kg⁻¹ per day, if agent effects on thymus will be assessed in gene levels.

High-fat diets affect energy and bone metabolism in growing rats.

BACKGROUND: High-fat diets are usually associated with greater weight (W) gain and body fat (BF). However, it is still unclear whether the type and amount of fat consumed influence BF. Additionally, dietary fat intake may also have consequences on skeletal health. OBJECTIVE: To evaluate in healthy growing rats the effects of high-fat diets and type of dietary fat intake (saturated or vegetable oils) on energy and bone metabolism. METHODS: At weaning, male Wistar rats (n = 50) were fed either a control diet (C; fat = 7% w/w) or a high-fat diet (20% w/w) containing either: soybean oil, corn oil (CO), linseed oil (LO), or beef tallow (BT) for 8 weeks. Zoometric parameters, BF, food intake and digestibility, and total and bone alkaline phosphatase (b-AP) were assessed. Total skeleton bone mineral density (BMD) and content (BMC), BMC/W, spine BMD, and bone volume (static-histomorphometry) were measured. RESULTS: Animals fed BT diet achieved lower W versus C. Rats fed high-fat vegetable oil diets showed similar effects on the zoometric parameters but differed in BF. BT showed the lowest lipid digestibility and BMC. In contrast, high vegetable oil diets produced no significant differences in BMC, BMC/W, BMD, spine BMD, and bone volume. Marked differences were observed for LO and BT groups in b-AP and CO and BT groups in bone volume. CONCLUSION: BT diet rich in saturated fatty acids had decreased digestibility and adversely affected energy and bone metabolisms, in growing healthy male rats. There were no changes in zoometric and bone parameters among rats fed high vegetable oil diets.

The inhibition of fat cell proliferation by n-3 fatty acids in dietary obese mice.

BACKGROUND: Long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) of marine origin exert multiple beneficial effects on health. Our previous study in mice showed that reduction of adiposity by LC n-3 PUFA was associated with both, a shift in adipose tissue metabolism and a decrease in tissue cellularity. The aim of this study was to further characterize the effects of LC n-3 PUFA on fat cell proliferation and differentiation in obese mice. METHODS: A model of inducible and reversible lipoatrophy (aP2-Cre-ERT2 PPARγL2/L2 mice) was used, in which the death of mature adipocytes could be achieved by a selective ablation of peroxisome proliferator-activated receptor γ in response to i.p. injection of tamoxifen. Before the injection, obesity was induced in male mice by 8-week-feeding a corn oil-based high-fat diet (cHF) and, subsequently, mice were randomly assigned (day 0) to one of the following groups: (i) mice injected by corn-oil-vehicle only, i.e."control" mice, and fed cHF; (ii) mice injected by tamoxifen in corn oil, i.e. "mutant" mice, fed cHF; (iii) control mice fed cHF diet with15% of dietary lipids replaced by LC n-3 PUFA concentrate (cHF+F); and (iv) mutant mice fed cHF+F. Blood and tissue samples were collected at days 14 and 42. RESULTS: Mutant mice achieved a maximum weight loss within 10 days post-injection, followed by a compensatory body weight gain, which was significantly faster in the cHF as compared with the cHF+F mutant mice. Also in control mice, body weight gain was depressed in response to dietary LC n-3 PUFA. At day 42, body weights in all groups stabilized, with no significant differences in adipocyte size between the groups, although body weight and adiposity was lower in the cHF+F as compared with the cHF mice, with a stronger effect in the mutant than in control mice. Gene expression analysis documented depression of adipocyte maturation during the reconstitution of adipose tissue in the cHF+F mutant mice. CONCLUSION: Dietary LC n-3 PUFA could reduce both hypertrophy and hyperplasia of fat cells in vivo. Results are in agreement with the involvement of fat cell turnover in control of adiposity.