Fish oil supplementation attenuates changes in plasma lipids caused by dexamethasone treatment in rats

A Preliminary Study on Hepatoprotective, Hypolipidemic and Aortic Morphometric Effects of Omega-3-Rich Fish Oil in Hypercholesterolemic Mice

This study aims to evaluate the hepatoprotective, hypolipidemic and aortic morphometric effects of fish oil rich in omega-3 in hypercholesterolemic BALB/c mice. This is an experimental model that included 16 male BALB/c mice (Mus musculus) divided into three groups (G1 (standard commercial chow and 0.9% saline solution), G2 (hypercholesterolemic diet and 0.9% saline solution) and G3 (hypercholesterolemic diet and fish oil)) for 8 weeks. There was no significant difference in the treatment with omega-3-rich fish oil in the lipid profile (p > 0.05). In the histological analysis, group G2 detected the presence of hepatitis and liver tissue necrosis, but this was not observed in group G3. As for the morphometry in the light area of the vessel, the G1 group had a higher score (2.62 ± 0.36 mm2) when compared to G2 (2.10 ± 0.16 mm2) and G3 (2.26 ± 0.25 mm2) (p < 0.05). The vessel wall thickness did not differ between the groups (p > 0.05). It is concluded that supplementation with fish oil rich in omega-3 carried out in this study may have a protective effect on liver tissue, but it has not yet improved the lipid and morphometric profile. Despite this research being preliminary, it is a relevant study with future prospects for improving the doses of EPA and DHA in order to better elucidate the benefits of fish oil in models of dyslipidemia.

Oral cortisol and dexamethasone intake: Differential physiology and transcriptional responses in the marine juvenile Sparus aurata

This study approached the long-term oral administration of cortisol (F) and dexamethasone (DEX), two synthetic glucocorticoids, compared to a control group (CT) in the juveniles of a marine teleost, the gilthead seabream (Sparus aurata). Physiologically, DEX treatment impaired growth, which appears to be linked to carbohydrate allocation in muscle and liver, hepatic triglycerides depletion, and reduced hematocrit. Hypophyseal gh mRNA expression was 2-fold higher in DEX than in CT or F groups. Similarly, hypothalamic trh and hypophyseal pomcb followed this pattern. Plasma cortisol levels were significantly lower in DEX than in CT, while F presented intermediate levels. In the posterior intestine, measured short circuit-current (Isc) was more anion absorptive in CT and F compared to the DEX group, whereas Isc remained unaffected in the anterior intestine. The derived transepithelial electric resistance (TEER) significantly differed between intestinal regions in the DEX group. These results provide new insights to understand better potential targeted biomarkers indicative of the differential glucocorticoid or mineralocorticoid-receptors activation in fish.

Fish Oil Supplementation Improves the Repeated-Bout Effect and Redox Balance in 20-30-Year-Old Men Submitted to Strength Training

Herein, we investigated the effect of fish oil supplementation combined with a strength-training protocol, for 6 weeks, on muscle damage induced by a single bout of strength exercise in untrained young men. Sixteen men were divided into two groups, supplemented or not with fish oil, and they were evaluated at the pre-training period and post-training period. We investigated changes before and 0, 24, and 48 h after a single hypertrophic exercise session. Creatine kinase (CK) and lactate dehydrogenase (LDH) activities, plasma interleukin-6 (IL-6) and C-reactive protein (CRP) levels, and the redox imbalance were increased in response to the single-bout session of hypertrophic exercises at baseline (pre-training period) and decreased during the post-training period in the control group due to the repeated-bout effect (RBE). The fish oil supplementation exacerbated this reduction and improved the redox state. In summary, our findings demonstrate that, in untrained young men submitted to a strength-training protocol, fish oil supplementation is ideal for alleviating the muscle injury, inflammation, and redox imbalance induced by a single session of intense strength exercises, highlighting this supplementation as a beneficial strategy for young men that intend to engage in strength-training programs.

Effects of Fish Oil Supplementation on Oxidative Stress Biomarkers and Liver Damage in Hypercholesterolemic Rats

Metabolic syndrome, especially its component related to dyslipidemia, is related to the development of nonalcoholic fatty liver disease (NAFLD), which is a disease with a significant global prevalence. Supplementation with omega-3 polyunsaturated fatty acids emerged as a complementary therapeutic possibility for dyslipidemia, but its benefits are questioned. This paper aims at evaluating the effects of fish oil supplementation in rats with hypercholesterolemia induced by hypercholesterolemic diet (HD). The study design is based on an experimental model in which the animals were randomly divided into 3 groups: G1 (standard commercial feed + saline solution); G2 (hypercholesterolemic diet + saline solution) and G3 (hypercholesterolemic diet + fish oil) over a period of 16 weeks. Metabolic control parameters and oxidative stress biomarkers were evaluated according to standardized methodologies. The G3 group showed significantly lower values of plasma concentrations of TG, and hepatic myeloperoxidase as well as higher erythrocyte superoxide dismutase activity (p < 0.05). Regarding histopathological analysis, there was lipid accumulation in the liver of animals from group G2; meanwhile, hepatocytes reorganization and expressive reduction of lipid vacuoles and hepatic TG content was observed in group G3. This study demonstrated how fish oil supplementation reduced the plasma concentration and hepatic content of triglycerides, as well as liver tissue damage in histopathological analysis.

Improvement in serum lipids and liver morphology after supplementation of the diet with fish oil is more evident under regular feeding conditions than under high-fat or mixed diets in rats

BACKGROUND

Dietary n- 3 polyunsaturated fatty acids (PUFAs) have a role in preventing cardiovascular and hepatic diseases. However, their effects might differ significantly depending on individual dietary patterns. The aim of the present study was to evaluate the effects of dietary supplementation with ω-3 fatty acids (FA), administered in different schedules, on hepatic and aortic histological structure, lipid profile, and body weight (BW) in male Wistar rats under standard (SD), high-fat diet (HFD) and mixed feeding conditions.

METHODS

PUFA treatment consisted of the administration of 50 mg/kg fish oil (FO) daily by oral gavage. HFD was obtained by adding a suspension of 4% cholesterol, thiouracil and cholic acid to the animals' drinking water. The rats were maintained on the diets for 6 weeks, and different schedules of PUFA administration were used. At 14, 28, and 42 days, the morphology of liver and aortic samples and the levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), and triglycerides (TG) were assessed.

RESULTS

The HFD groups exhibited significant hyperlipidemia and aortic inflammation, with progression to atherogenesis after 6 weeks. Administration of PUFAs slightly attenuated the aortic changes in these groups and reduced the liver's tendency to steatosis. FO-induced metabolic improvement was more evident in SD than in HFD rats. For instance, after the first 2 weeks, SD animals that received PUFAs had significantly increased HDL levels vs. controls (62.375 ± 4.10 vs. 52.625 ± 8.38 mg/dL, P < 0.05), but HFD rats did not, and decreased TG levels were observed exclusively in the SD rats (57.6 ± 4.09 vs. 66 ± 4.69 mg/dL, P < 0.05). After 6 weeks of n- 3 PUFA administration, LDL was significantly lower in the SD rats than in controls (13.67 ± 4.13 vs. 30.83 ± 2.86 mg/dL, P < 0.001), but the decrease in the HFD rats, although significant (49.17 ± 5.85 mg/dL vs. 57.17 ± 4.96 g/dL, P < 0.05), was not as marked. In the mixed-diet groups, administration of 50 mg/kg/day FO for 14 days under SD conditions following 4 weeks of HFD slightly decreased TG (86.625 ± 11.67 vs. 73 ± 4.52 mg/dL, P < 0.05) and increased HDL (45.875 ± 5.28 vs. 56 ± 3.16 mg/dL). However, in these animals, n-3 PUFA administration had no effect on LDL or TC. Administration of half of the above dose failed to improve any biochemical parameters. FO protected against excessive weight gain mainly under SD conditions.

CONCLUSIONS

The results show that FO confers more protection against cardiovascular risk factors (increased LDL and TG, decreased HDL) and liver lipid accumulation when given to rats consuming regular diets than when given to rats consuming a high-fat diet. This argues that priority should be given to consumption of a healthy diet rather than to the use of supplements. The effectiveness of n-3 PUFAs might be reduced in the case of hyperlipidic intake or after consumption of a high-fat diet.

Enriched environment ameliorates dexamethasone effects on emotional reactivity and metabolic parameters in mice

Convincing evidence shows that stress is associated with the development and course of psychiatric and metabolic disorders. The hypothalamic-pituitary-adrenal (HPA) axis mediates the stress response, a cascade of events that culminate in the release of glucocorticoids from the adrenal cortex. Chronic hypercortisolism typically characterizes stress-related illnesses, such as depression, anxiety, and metabolic syndrome. Considering previous studies pointing that environmental enrichment (EE) mitigates the deleterious effects of stress on neurobiological systems, we hypothesized that EE can confer resiliency against prolonged glucocorticoid administration-induced behavioral and metabolic alterations in mice. In this regard, three-month-old male Swiss mice were exposed to a four-week period of standard environment (SE) or EE. After this period, still in the respective environments, dexamethasone was administered intraperitoneally (i.p.) at a dose of 4 mg/kg, for 21 consecutive days, in order to generate the emotional-related behavioral outcomes, as previously described. It is demonstrated herein that EE prevents the dexamethasone-induced anxiety-like and passive stress-coping behaviors, as observed in the open field and tail suspension tests. Moreover, EE mitigated the hyperproteinemia and body weight loss induced by excess dexamethasone and decreased basal glucose levels. Taken together, these results support the hypothesis that EE attenuates the effects of chronic administration of synthetic glucocorticoids in mice, a strategy that may be translated to the clinical perspective.

Effects of Dietary Fat Sources during Late Gestation on Colostrum Quality and Mammary Gland Inflammation in Lipopolysaccharide-Challenged Sows

Simple Summary

In the present study, late gestating sows were challenged with lipopolysaccharide (LPS) endotoxin, which can impair the immune system of mammary gland cells and result in an inflammatory response. Additionally, the LPS-treated sows were fed 3% soybean oil (SO), 3% coconut oil (CO) or 3% fish oil (FO) diets and were used to study the effect of fat sources on the colostrum quality and mammary gland inflammation of sows exposed to immune challenge. The results show that FO inclusion exerted anti-inflammatory effects in mammary glands and counteracted the LPS-induced damaged colostrum synthesis and pro-inflammatory response when compared to CO diets. These findings suggest that fatty acid profiles of different oil types in late gestation differentially affect metabolic health in sows, but a longer period of FO supplementation to sows is needed to determine a positive effect on piglets.

Abstract

This study aimed to investigate the effects of maternal lipopolysaccharide (LPS) challenge and dietary fat sources on colostrum quality and inflammatory response in sows. Sixty Landrace × Yorkshire sows were randomly assigned to three dietary treatments supplemented with 3% soybean oil (SO), 3% coconut oil (CO) or 3% fish oil (FO), respectively, from Day 90 of gestation until parturition. On Day 112 of gestation, half the sows from each dietary treatment were challenged with LPS (10 μg/kg BW) or saline. The results showed that maternal LPS challenge decreased colostrum yield and dry matter content. A similar pattern of changes was observed for body weight gain and colostrum intake in piglets from LPS-challenged sows. Maternal LPS challenge increased the levels of tumor necrosis factor α (TNFα), interleukin 1β (IL1β) and IL6 in colostum, and the mRNA abundance of IL6, IL1β and TNFα and the phosphorylation level of p65 in mammary glands. However, the responses of these variables to LPS treatment were lower in sows fed a FO diet. In conclusion, maternal immune challenge reduced the growth performance of piglets by decreasing colostrum yield and intake by piglets, and dietary supplementation with FO in sows attenuates the LPS-induced inflammatory response in mammary glands.

Protocatechuic acid exhibits hepatoprotective, vasculoprotective, antioxidant and insulin-like effects in dexamethasone-induced insulin-resistant rats

Protocatechuic acid (PCA), the natural phenolic antioxidant, reportedly exhibited hypoglycemic and insulin-like effects. Recent studies have reported its cardioprotective effect in glucocorticoid (GC)-induced hypertensive rats. Nevertheless, its beneficial role has not been investigated in the setting of GCs excess-induced insulin resistance. This study aimed to investigate the possible protective potential and the plausible mechanisms of pretreatment with PCA against GCs-induced insulin resistance, liver steatosis and vascular dysfunction. Insulin resistance was induced in male Wistar rats by a 7-day treatment with dexamethasone (DEX) (1 mg/kg/day, i.p.). PCA (50, 100 mg/kg/day, orally) was started 7 days before DEX administration and continued during the test period. PCA significantly and dose-dependently attenuated DEX-induced a) glucose intolerance (↓ AUC_OGTT), b) hyperglycemia (↓ fasting blood glucose), c) impaired insulin sensitivity [↓fasting plasma insulin and homeostasis model assessment of insulin resistance (HOMA-IR) index)] and d) dyslipidemia (↓total cholesterol, triglycerides, low-density lipoprotein-cholesterol and very low-density lipoprotein-cholesterol). PCA mitigated DEX-induced liver steatosis with associated reduction in serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Moreover, PCA ameliorated DEX-induced vascular dysfunction and enhanced ACh-induced relaxation in aortic rings. The metabolic ameliorating effects of PCA might be attributed to the enhanced insulin signaling in soleus muscles (↑AKT phosphorylation) and mitigating gluconeogenesis (↓ hepatic mRNA expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). The vasculoprotective effect of PCA might be related to its ability to restore normal mRNA expression of [endothelial nitric oxide synthase (eNOS) and NADPH Oxidase 4 (NOX4)]. PCA restored normal oxidative balance [↓ oxidant species, malondialdehyde (MDA) and (↑ antioxidant superoxide dismutase (SOD)]. The findings herein reveal for the first time that PCA may be taken as a supplement with GCs to limit their metabolic and vascular side effects through its hypoglycemic, insulin-sensitizing, hypolipidemic and antioxidant effects.

Ozone-Induced Vascular Contractility and Pulmonary Injury Are Differentially Impacted by Diets Enriched With Coconut Oil, Fish Oil, and Olive Oil

Fish, olive, and coconut oil dietary supplementation have several cardioprotective benefits, but it is not established if they protect against air pollution-induced adverse effects. We hypothesized that these dietary supplements would attenuate ozone-induced systemic and pulmonary effects. Male Wistar Kyoto rats were fed either a normal diet, or a diet supplemented with fish, olive, or coconut oil for 8 weeks. Animals were then exposed to air or ozone (0.8 ppm), 4 h/day for 2 days. Ozone exposure increased phenylephrine-induced aortic vasocontraction, which was completely abolished in rats fed the fish oil diet. Despite this cardioprotective effect, the fish oil diet increased baseline levels of bronchoalveolar lavage fluid (BALF) markers of lung injury and inflammation. Ozone-induced pulmonary injury/inflammation were comparable in rats on normal, coconut oil, and olive oil diets with altered expression of markers in animals fed the fish oil diet. Fish oil, regardless of exposure, led to enlarged, foamy macrophages in the BALF that coincided with decreased pulmonary mRNA expression of cholesterol transporters, cholesterol receptors, and nuclear receptors. Serum microRNA profile was assessed and demonstrated marked depletion of a variety of microRNAs in animals fed the fish oil diet, several of which were of splenic origin. No ozone-specific changes were noted. Collectively, these data indicate that although fish oil offered vascular protection from ozone exposure, it increased pulmonary injury/inflammation and impaired lipid transport mechanisms resulting in foamy macrophage accumulation, demonstrating the need to be cognizant of potential off-target pulmonary effects that might offset the overall benefit of this vasoprotective supplement.

Neuroprotective Effects of dl-3-n-Butylphthalide against Doxorubicin-Induced Neuroinflammation, Oxidative Stress, Endoplasmic Reticulum Stress, and Behavioral Changes

Doxorubicin (DOX) is a broad-spectrum antitumor drug while its use is limited due to its neurobiological side effects associated with depression. We investigated the neuroprotective efficacy of dl-3-n-butylphthalide (dl-NBP) against DOX-induced anxiety- and depression-like behaviors in rats. dl-NBP was given (30 mg/kg) daily by gavage over three weeks starting seven days before DOX administration. Elevated plus maze (EPM) test, forced swimming test (FST), and sucrose preference test (SPT) were performed to assess anxiety- and depression-like behaviors. Our study showed that the supplementation of dl-NBP significantly mitigated the behavioral changes induced by DOX. To further explore the mechanism of neuroprotection induced by dl-NBP, several biomarkers including oxidative stress markers, endoplasmic reticulum (ER) stress markers, and neuroinflammatory cytokines in the hippocampus were quantified. The results showed that dl-NBP treatment alleviated DOX-induced neural apoptosis. Meanwhile, DOX-induced oxidative stress and ER stress in the hippocampus were significantly ameliorated in dl-NBP pretreatment group. Our study found that dl-NBP alleviated the upregulation of malondialdehyde (MDA), nitric oxide (NO), CHOP, glucose-regulated protein 78 kD (GRP-78), and caspase-12 and increased the levels of reduced glutathione (GSH) and activities of catalase (CAT), glutathione reductase (GR), and glutathione peroxidase (GPx) in the hippocampus of rats exposed to DOX. Additionally, the gene expression of interleukin-6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-alpha (TNF-α) and protein levels of inducible nitric oxide synthase (iNOS) were significantly increased in DOX-treated group, whereas DOX-induced neuroinflammation was significantly attenuated in dl-NBP supplementation group. In conclusion, dl-NBP could alleviate DOX-induced anxiety- and depression-like behaviors via attenuating oxidative stress, ER stress, inflammatory reaction, and neural apoptosis, providing a basis as a therapeutic potential against DOX-induced neurotoxicity.

Effects of adipokine zinc-α2-glycoprotein on adipose tissue metabolism after dexamethasone treatment

Zinc-α2-glycoprotein (ZAG) has been demonstrated to play a role in stimulating lipid mobilization under normal conditions. However, further studies are required to determine whether ZAG overexpression can alleviate the reduction in plasma lipid levels under stress conditions. In the present study, we investigated the effects of ZAG on lipometabolism in white adipose tissue (WAT) after dexamethasone (DEX) stimulation using C57BL/6 male mice as the experimental models. Transcript and protein levels of genes associated with the β-adrenoreceptor (β-AR)/cyclic adenosine monophosphate/protein kinase a (PKA) pathway, lipid mobilization, and energy metabolism were determined by quantitative real-time polymerase chain reaction and Western blotting. Plasma levels of nonesterified fatty acid (NEFA) were measured using an automatic biochemical analyzer. Results indicated that plasma NEFA levels were decreased in the DEX group, but NEFA levels were rescued by ZAG overexpression. ZAG overexpression resulted in the upregulation of β3-AR and phosphorylated PKA protein relative to those of the DEX group. Analysis of lipometabolism showed that protein levels of phosphorylated hormone-sensitive lipase was reduced upon DEX treatment but were restored by ZAG overexpression. For energy metabolism, ZAG significantly upregulated the protein expression of carnitine palmitoyltransferase1a and cytochrome c oxidase subunit 1 relative to those of the DEX group. In conclusion, ZAG could alleviate DEX-induced decrease in plasma NEFA levels and this could be associated with the promoting lipid mobilization in WAT.

Impact of Fish Oil Supplementation and Interruption of Fructose Ingestion on Glucose and Lipid Homeostasis of Rats Drinking Different Concentrations of Fructose

Background. Continuous fructose consumption may cause elevation of circulating triacylglycerol. However, how much of this alteration is reverted after the removal of fructose intake is not known. We explored this question and compared the efficacy of this approach with fish oil supplementation. Methods. Male Wistar rats were divided into the following groups: control (C), fructose (F) (water intake with 10% or 30% fructose for 9 weeks), fish oil (FO), and fructose/fish oil (FFO). Fish oil was supplemented only for the last 33 days of fructose ingestion. Half of the F group remained for additional 8 weeks without fructose ingestion (FR). Results. Fructose ingestion reduced food intake to compensate for the increased energy obtained through water ingestion, independent of fructose concentration. Fish oil supplementation exerted no impact on these parameters, but the removal of fructose from water recovered both ingestion behaviors. Plasma triacylglycerol augmented significantly during the second and third weeks (both fructose groups). Fish oil supplementation did not attenuate the elevation in triacylglycerol caused by fructose intake, but the interruption of sugar consumption normalized this parameter. Conclusion. Elevation in triacylglyceridemia may be recovered by removing fructose from diet, suggesting that it is never too late to repair improper dietary habits.

Glucose homeostasis in rats treated with 4-vinylcyclohexene diepoxide is not worsened by dexamethasone treatment

4-vinilcyclohexene diepoxide (4-VCD) causes premature ovarian failure and may result in estrogen deficiency, characterizing the transition to estropause in rodents (equivalent to menopause in women). Estropause/menopause is associated with metabolic derangements such as glucose intolerance and insulin resistance. Glucocorticoids (GCs) are known to exert diabetogenic effects. Thus, we aimed to investigate whether rats with premature ovarian failure are more prone to the diabetogenic effects of GC. For this, immature female rats received daily injections of 4-VCD [160mg/kg body weight (b.w.), intraperitoneally (i.p.)] for 15 consecutive days, whereas control rats received vehicle. After 168days of the completion of 4-VCD administration, rats were divided into 4 groups: CTL-received daily injections of saline (1mL/kg, b.w., i.p.) for 5days; DEX-received daily injections of dexamethasone (1mg/kg, b.w., i.p.) for 5days; VCD-treated as CTL group; VCD+DEX-treated as DEX group. Experiments and euthanasia occurred one day after the last dexamethasone injection. 4-VCD-treated rats exhibited ovary hypotrophy and reduced number of preantral follicles (p<0.05). Premature ovarian failure had no impact on the body weight gain or food intake, but both were reduced by the effects of dexamethasone. The increase in blood glucose, plasma insulin and triacylglycerol levels as well as the reduction in insulin sensitivity caused by dexamethasone treatment was not exacerbated in the VCD+DEX group of rats. Premature ovarian failure did change neither the hepatic content of glycogen and triacylglycerol nor the glycerol release from perigonadal adipose tissue. Glucose intolerance was observed in the VCD group after an ipGTT (p<0.05), but not after an oral glucose challenge. Glucose intolerance and compensatory pancreatic β-cell mass caused by GC were not modified by ovarian failure in the VCD+DEX group. We conclude that reduced ovarian function has no major implications on the diabetogenic effects promoted by GC treatment, indicating that other factors related to aging may make rats more vulnerable to GC side effects on glucose metabolism.

Long Chain Omega-3 Polyunsaturated Fatty Acid Supplementation Alleviates Doxorubicin-Induced Depressive-Like Behaviors and Neurotoxicity in Rats: Involvement of Oxidative Stress and Neuroinflammation

Doxorubicin (DOX) is a chemotherapeutic agent widely used in human malignancies. Its long-term use can cause neurobiological side-effects associated with depression. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs), the essential fatty acids found in fish oil, possess neuroprotecitve and antidepressant activities. Thus, the aim of this study was to explore the potential protective effects of ω-3 PUFAs against DOX-induced behavioral changes and neurotoxicity. ω-3 PUFAs were given daily by gavage (1.5 g/kg) over three weeks starting seven days before DOX administration (2.5 mg/kg). Open-field test (OFT) and forced swimming test (FST) were conducted to assess exploratory activity and despair behavior, respectively. Our data showed that ω-3 PUFAs supplementation significantly mitigated the behavioral changes induced by DOX. ω-3 PUFAs pretreatment also alleviated the DOX-induced neural apoptosis. Meanwhile, ω-3 PUFAs treatment ameliorated DOX-induced oxidative stress in the prefrontal cortex and hippocampus. Additionally, gene expression of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α, and the protein levels of NF-κB and iNOS were significantly increased in brain tissues of DOX-treated group, whereas ω-3 PUFAs supplementation significantly attenuated DOX-induced neuroinflammation. In conclusion, ω-3 PUFAs can effectively protect against DOX-induced depressive-like behaviors, and the mechanisms underlying the neuroprotective effect are potentially associated with its anti-oxidant, anti-inflammatory, and anti-apoptotic properties.