Dietary supplementation with conjugated linoleic acid plus n-3 polyunsaturated fatty acid increases food intake and brown adipose tissue in rats

Conjugated linoleic acid (CLA) reduces HFD-induced obesity by enhancing BAT thermogenesis and iWAT browning via the CD36-AMPK pathway

The antiobesity effect of conjugated linoleic acid (CLA) has been reported. However, the underlying mechanisms have not been fully clarified. Thus, this study aimed to investigate the effects of CLA on thermogenesis of interscapular brown adipose tissue (iBAT) and browning of inguinal subcutaneous white adipose tissue (iWAT) and explore the possible signaling pathway. The in vivo results showed that CLA enhanced the O2 consumption and heat production in HFD (high-fat diet)-fed female mice by roughly 38%. Meanwhile, CLA increased the average iBAT temperature by 2°C at the room temperature and cold exposure, respectively. Correspondingly, CLA caused 1.6- and 2.4-fold increases in the expression of UCP1 (uncoupling protein 1) of BAT and iWAT, respectively, suggesting the activated iBAT thermogenesis and iWAT browning in HFD-fed female mice. Meanwhile, CLA could promote the formation of brown and beige adipocytes in differentiated stromal vascular cells (SVCs) isolated from iBAT and iWAT (the expressions of UCP1 were promoted by about twofold changes). In possible mechanisms, CLA stimulated the expression of CD36 and the activation of the AMPK pathway in mice iBAT and iWAT as well as the differentiated SVCs. However, inhibition of CD36 and AMPK (adenosine 5'-monophosphate-activated protein kinase) abolished the promotive effects of CLA on brown and beige adipocytes formation. Hence, we showed that CLA reduced HFD-induced obesity through enhancing iBAT thermogenesis and iWAT browning via the  CD36-AMPK pathway.

Maternal L-carnitine supplementation promotes brown adipose tissue thermogenesis of newborn goats after cold exposure

Brown adipose tissue (BAT) is an important component of energy expenditure and necessary to maintain body temperature for newborn mammals. In the previous study, we found that L-carnitine was enriched in BAT and promoted BAT adipogenesis and thermogenesis in goat brown adipocytes. However, whether dietary L-carnitine regulates BAT heat production and energy expenditure in lambs remains unclear. In this study, maternal L-carnitine supplementation elevated the rectal temperature, as well as the expression of UCP1 and mitochondrial DNA content to promote BAT thermogenesis in newborn goats. Moreover, maternal L-carnitine supplementation increased the levels of triglycerides (TG), non-esterified fatty acids (NEFA), and lactate in plasma, as well as the content of lipid droplet and glycogen in BAT of newborn goats. Lipidomic analysis showed that maternal L-carnitine supplementation remodeled the lipid composition of BAT in newborn goats. L-carnitine significantly increased the levels of TG and diglyceride (DG) and decreased the levels of glycerophospholipids and sphingolipids in BAT. Further studies showed that L-carnitine promoted TG and glycogen deposition in brown adipocytes through AMPKα. Our results indicate that maternal L-carnitine supplementation promotes BAT development and thermogenesis in newborn goats and provides new evidence for newborn goats to maintain body temperature in response to cold exposure.

Omega-3 offers better hypothalamus protection by decreasing POMC expression and elevating ghrelin hormone: a prospective trial to overcome methotrexate-induced anorexia

PURPOSE

Methotrexate (MTX) therapy is widely used in treatment of different types of diseases including inflammatory diseases, autoimmune disorders, and cancer. However, most of patients respond well to MTX, they suffer from multiple side effects including severe anorexia. Omega-3 fatty acid possesses many beneficial biological activities. Therefore, the objective of our study is to explore the effect of the combined modality of omega-3 (400 mg/kg/day) in MTX-induced anorexia in rats.

METHODS

The effect of MTX alone and in combination with omega-3 on the body weight, ghrelin hormone level, histopathological findings of taste buds and hypothalamus and POMC gene expression were investigated.

RESULTS

Interestingly, the capability of omega-3 to overcome the anorexic effect of MTX could be manifested by controlling weight loss, increasing serum HDL, elevating the ghrelin level as well as reducing both lesions within taste buds and hypothalamus and hypothalamic POMC gene expression.

CONCLUSIONS

our findings revealed that the omega-3 might be used as a complementary supplement during the MTX therapy to ameliorate its anorexic effect.

The status of ω-3 PUFAs influence chronic unpredicted mild stress-induced metabolic side effects in rats through INSIG/SREBP pathway

Metabolic disturbances, including lipid metabolism, bone metabolism, and glycometabolism, are common in depression. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs), which are reported to possess antidepressant effect, have also been shown to regulate metabolism. To further clarify the potential link between ω-3 PUFAs and stress-induced metabolic disturbances, metabolic-related parameters including body weight, visceral fat, fatty acid composition and serum parameters, such as serum lipids, free fatty acid (FFA), glucose (GLU), calcium and phosphorus in rats were measured. Moreover, hepatic insulin induced gene (INSIG)/sterol regulatory element binding protein (SREBP) pathway was also investigated. After 5 weeks of chronic unpredicted mild stress (CUMS) administration, rats were induced to a depressive-like state and exhibited decreased serum high-density lipoprotein (HDL-c), body weight and visceral fat, accompanied by altered C18:2n6c and ω-3/ω-6 PUFAs. Supplement of ω-3 PUFAs showed robust antidepressant effects and has beneficial effects on lipid profile. On the contrary, ω-3 PUFAs deficiency induced the visceral fat accumulation and decreased the serum calcium and phosphorus in stressed rats. Additionally, CUMS significantly increased hepatic expressions of SREBP-cleavage activating protein (SCAP)/SREBP-1 and decreased the expression of INSIG-1. This disturbance of SREBPs system is aggravated by ω-3 PUFAs deficiency and alleviated by ω-3 PUFAs supplementation. This study discloses the novel findings that ω-3 PUFAs deficiency will exacerbate the metabolic disturbances in stressed rats. Furthermore, supplementation of ω-3 PUFAs on individuals with a high risk of depression might be an effective way to prevent metabolic disorders accompanied by depression with the involvement of INSIG/SREBP pathway.

Effects of intermittent dietary supplementation with conjugated linoleic acid and fish oil (EPA/DHA) on body metabolism and mitochondrial energetics in mice

Understanding the mitochondrial processes that contribute to body energy metabolism may provide an attractive therapeutic target for obesity and co-morbidities. Here we investigated whether intermittent dietary supplementation with conjugated linoleic (CLA, 18:2n-6), docosahexaenoic (22:6n-3, DHA) and eicosapentaenoic (20:5n-3, EPA) acids, either alone or in combination, changes body metabolism associated with mitochondrial functions in the brain, liver, skeletal muscle and brown adipose tissue (BAT). Male C57Bl/6 mice were divided into groups: CLA (50% cis-9, trans-11; 50% trans-10, cis-12), EPA/DHA (64% EPA; 28% DHA), CLA plus EPA/DHA or control (linoleic acid). Each mouse received 3 g/kg b.w. of the stated oil by gavage on alternating days for 60 days. Dietary supplementation with CLA or EPA/DHA increased body VO₂ consumption, VCO₂ production and energy expenditure, being fish oil (FO) the most potent even in combination with CLA. Individually, both oils reduced mitochondrial density in BAT. CLA supplementation alone also a) elevated the expression of uncoupling proteins in soleus, liver and hippocampus and the uncoupling activity in the last two, ad this effect was associated with reduced hydrogen peroxide production in hippocampus; b) increased proteins related to mitochondrial fission in liver. EPA/DHA supplementation alone also a) induced mitochondrial biogenesis in liver, soleus and hippocampus associated with increased expression of PGC1-α; b) induced proteins related to mitochondrial fusion in the liver, and fission and fusion in the hippocampus. Therefore, this study shows changes on mitochondrial mechanisms induced by CLA and/or EPA/DHA that can be associated with elevated body energy expenditure.

Fish oil as a potential activator of brown and beige fat thermogenesis

Numerous studies have shown that feeding rodents n-3 polyunsaturated fatty acids attenuates adiposity. Moreover, meta-analyses of human dietary intervention studies indicate that fish oil (eicosapentaenoic and docosahexaenoic acid) supplementation might reduce waist circumference. A recent line of research suggests that browning of white adipose depots and activation of uncoupled respiration in brown fat contributes to these effects. This mini-review summarizes the observations in rodents, highlights several mechanisms that might explain these observations and discusses the translational potential. Given the available in vivo evidence and the ability of human adipocytes to aquire a beige phenotype in response to eicosapentaenoic acid incubation, future studies should test the hypothesis that fish oil activates thermogenic brown and beige adipose tissue in humans.

Eicosapentaenoic acid regulates brown adipose tissue metabolism in high-fat-fed mice and in clonal brown adipocytes

Brown adipose tissue (BAT) plays a key role in energy expenditure through its specialized thermogenic function. Therefore, BAT activation may help prevent and/or treat obesity. Interestingly, subcutaneous white adipose tissue (WAT) also has the ability to differentiate into brown-like adipocytes and may potentially contribute to increased thermogenesis. We have previously reported that eicosapentaenoic acid (EPA) reduces high-fat (HF)-diet-induced obesity and insulin resistance in mice. Whether BAT mediates some of these beneficial effects of EPA has not been determined. We hypothesized that EPA activates BAT thermogenic program, contributing to its antiobesity effects. BAT and WAT were harvested from B6 male mice fed HF diets supplemented with or without EPA. HIB 1B clonal brown adipocytes treated with or without EPA were also used. Gene and protein expressions were measured in adipose tissues and H1B 1B cells by quantitative polymerase chain reaction and immunoblotting, respectively. Our results show that BAT from EPA-supplemented mice expressed significantly higher levels of thermogenic genes such as PRDM16 and PGC1α and higher levels of uncoupling protein 1 compared to HF-fed mice. By contrast, both WATs (subcutaneous and visceral) had undetectable levels of these markers with no up regulation by EPA. HIB 1B cells treated with EPA showed significantly higher mRNA expression of PGC1α and SIRT2. EPA treatment significantly increased maximum oxidative and peak glycolytic metabolism in H1B 1B cells. Our results demonstrate a novel and promising role for EPA in preventing obesity via activation of BAT, adding to its known beneficial anti-inflammatory effects.

Fish oil supplementation alleviates depressant-like behaviors and modulates lipid profiles in rats exposed to chronic unpredictable mild stress

Background

Patients with major depressive disorder have a higher prevalence and incidence of dyslipidemia. However, clinical studies concerning the association between lipid levels and depression are inconsistent. Adipokines (like leptin and adiponectin) and ghrelin are strongly associated with lipid metabolism. Fish oil, which is reported to possess antidepressant effect, also have beneficial effects on lipid metabolism and the cardiovascular system. In the present study, we investigated lipid metabolism in rats exposed to chronic unpredictable mild stress (CUMS) and the effect of fish oil on lipid profiles, aforementioned adipokines and ghrelin.

Methods

Sucrose preference test (SPT), open field test (OFT) and forced swimming test (FST) were used to evaluate the antidepressant-like effects of fish oil. After the behavior tests, peripheral blood were collected. Serum parameters, including fasting triglyceride (TG), total cholesterol (TCH), high density lipoprotein-cholesterol (HDL-c), low density lipoprotein-cholesterol (LDL-c), free fatty acid (FFA), glucose (GLU), adipokines (leptin, adiponectin) and ghrelin were assayed.

Results

After 5 weeks of CUMS procedures, rats were induced to depressive-like state, and exhibited increased serum levels of TCH, HDL-c, FFA and decreased serum levels of leptin and ghrelin, whereas the serum status of adiponectin, GLU, TG and LDL-c remained stable. Fish oil treatment showed robust antidepressant effect and reversed the stress-induced lipid disturbance and decrease in serum concentration of ghrelin.

Conclusions

Our results suggested that CUMS altered the serum levels of lipid profiles, leptin and ghrelin in rats. Fish oil supplementation not only provided antidepressant-like effects, but also reversed the altered lipid profiles and ghrelin level in serum. Our data indicated that fish oil treatment exerts anti-depressant effect and regulates lipid disturbance simultaneously.

Nutritional ingredients modulate adipokine secretion and inflammation in human primary adipocytes

Nutritional factors such as casein hydrolysates and long chain polyunsaturated fatty acids have been proposed to exert beneficial metabolic effects. We aimed to investigate how a casein hydrolysate (eCH) and long chain polyunsaturated fatty acids could affect human primary adipocyte function in vitro. Incubation conditions with the different nutritional factors were validated by assessing cell vitality with lactate dehydrogenase (LDH) release and neutral red incorporation. Intracellular triglyceride content was assessed with Oil Red O staining. The effect of eCH, a non-peptidic amino acid mixture (AA), and long-chain polyunsaturated fatty acids (LC-PUFAs) on adiponectin and leptin secretion was determined by enzyme-linked immunosorbent assay (ELISA). Intracellular adiponectin expression and nuclear factor-κB (NF-κB) activation were analyzed by Western blot, while monocyte chemoattractant protein-1 (MCP-1) release was explored by ELISA. The eCH concentration dependently increased adiponectin secretion in human primary adipocytes through its intrinsic peptide bioactivity, since the non-peptidic mixture, AA, could not mimic eCH’s effects on adiponectin secretion. Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and DHA combined with arachidonic acid (ARA) upregulated adiponectin secretion. However, only DHA and DHA/ARA exerted a potentanti-inflammatory effect reflected by prevention of tumor necrosis factor-α (TNF-α) induced NF-κB activation and MCP-1 secretion in human adipocytes. eCH and DHA alone or in combination with ARA, may hold the key for nutritional programming through their anti-inflammatory action to prevent diseases with low-grade chronic inflammation such as obesity or diabetes.

Effects of dietary conjugated linoleic acid and biopolymer encapsulation on lipid metabolism in mice

Forty mice were randomly divided into four groups on the basis of the diet to be fed as follows: 5% (low) fat diet (T1: LF); 20% (high) fat diet (T2: HF); 20% fat containing 1% conjugated linoleic acid (CLA) (T3: HFC); and 20% fat containing 1% CLA with 0.5% biopolymers (T4: HFCB). The high-fat with CLA diet groups (HFC and HFCB) and the low-fat diet group (LF) tended to have lower body weights and total adipose tissue weights than those of the high-fat diet group (HF). Serum leptin and triglyceride were significantly lower in the high fat with CLA-fed groups (HFC and HFCB) and the low-fat diet group (LF) than those in the high-fat diet group (HF). It is noteworthy that the high-fat with CLA and biopolymers group (HFCB) showed the lowest serum triglyceride and cholesterol concentrations. In the high-fat-fed group (HF), voluntary travel distance as a measure of physical activity decreased after three weeks of feeding. However, the CLA-fed groups showed increased physical activity. The groups fed high-fat diets supplemented with CLA alone and with CLA and biopolymers had higher viscosity of small intestinal contents than that in the low- and high-fat dietary groups.

Incorporation of conjugated linoleic acid into brain lipids is not necessary for conjugated linoleic acid-induced reductions in feed intake or body fat in mice

Dietary conjugated linoleic acid (CLA) causes reduced feed intake (FI) and body fat (BF). It is unknown, though, if CLA incorporation into tissues, alterations in serum hormones, and/or appetite-regulating neuropeptides are involved. We hypothesized that CLA incorporation into brain lipids would be correlated with changes in appetite-regulating neuropeptide expression and reductions in FI and BF. Male mice (n = 150; 9 weeks old, ICR) received the control diet ad libitum (CON), 2% CLA diet ad libitum (CLA), or control diet pair-fed to the intake of CLA-fed mice for 1, 2, 3, 5, or 7 days. Both FI and body weight were measured daily, and a BF index was calculated. Liver, adipose, and brain fatty acids; serum insulin, leptin, and peptide YY; and arcuate nucleus neuropeptide Y, agouti-related protein, and α-melanocyte-stimulating hormone protein were determined. Mice fed CLA ate less (P < .05) than did the CON on days 1, 2, 3, and 7 but were leaner (P < .05) only on day 7. Mice that received the control diet pair-fed to the intake of CLA-fed mice did not differ in BF from the CON. By days 1 and 2, CLA isomers were incorporated into the liver and adipose but not in the brain. Insulin was increased in CLA-fed mice on days 5 and 7, and leptin was decreased on day 7. Peptide YY and the neuropeptides did not differ. Tissue CLA was not correlated with FI, body weight, or BF but was positively correlated with insulin and negatively correlated with leptin. The reduction in FI is not sufficient to cause the reduction in BF, and tissue CLA accumulation does not appear to be required.