Transgenic n-3 PUFAs enrichment leads to weight loss via modulating neuropeptides in hypothalamus

Triacylglycerol rich in docosahexaenoic acid regulated appetite via the mediation of leptin and intestinal epithelial functions in high-fat, high-sugar diet-fed mice

High-fat, high-sugar diet (HFHS) induced leptin resistance and intestinal epithelial dysfunction is implicated in hyperphagia and metabolic disorders. Numerous studies have demonstrated the efficacy of dietary interventions for reducing appetite. This study aims to investigate whether triacylglycerol rich in DHA (DHA-TG) could regulate appetite in mice fed with a HFHS diet and the mechanism by which it achieves that. DHA-TG could reduce food intake and regulate neuropeptides (POMC, AgRP, and NPY) expression in HFHS diet-fed mice. Hypothalamic transcriptome analysis reveals that these effects might be attributed to the role of DHA-TG in modulating hormone secretion and digestive system process. According to ELISA and RT-qPCR analysis, DHA-TG ameliorated leptin secretion and attenuated central leptin resistance induced by HFHS diet feeding. Besides, DHA-TG prevented the damage of intestinal epithelial barrier in nutritive obese mice by improving leptin sensitivity. Based on jejunal transcriptome analysis, DHA-TG also protected intestinal endocrine function, especially the secretion of another anorectic hormone, cholecystokinin (CCK), in HFHS diet-fed mice. Furthermore, DHA-TG was ineffective in repressing appetite, and improving gut leakage in leptin-deficient mice (ob/ob mice). In conclusion, DHA-TG has a potential to regulate appetite with the action of leptin, and intestinal epithelial functions in HFHS diet-fed mice.

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.

Therapeutic effects of different doses of prebiotic (isolated from Saccharomyces cerevisiae) in comparison to n-3 supplement on glycemic control, lipid profiles and immunological response in diabetic rats

BACKGROUND

The regular intake of fiber generates numerous health benefits. However, the efficacy depends on the duration of consumption and the ingested dose. Studies investigating the optimal dose are of interest to enable the inclusion of fiber in the routine treatment of diabetic patients.

OBJECTIVE

We aimed to evaluate the effects of different doses of β-glucan (BG-isolated from Saccharomyces cerevisiae), in comparison to n-3 supplement, on the inflammatory and metabolic parameters of Wistar rats induced to diabetes by streptozotocin.

METHODS

Forty animals were randomly divided into six groups receiving 0 mg/kg, 10 mg/kg, 20 mg/kg, or 40 mg/kg BG daily for 4 weeks or fish oil derivative [1000 mg/kg of omega-3 fatty acids (n-3)] for the same period. One additional group was composed of healthy controls. Serum metabolic and immunological parameters were evaluated by colorimetric and ELISA assays respectively. Histopathological analysis of the liver, small intestine and pancreas were also conducted. Significant changes due to BG intake were set into regression models with second-degree fit in order to estimate the optimal BG dose to achieve health benefits.

RESULTS

The animals that ingested BG had lower food and water intake (p < 0.05) than the negative control group (0 mg/kg). However, consumption was still elevated in comparison to healthy controls. Blood glucose and serum levels of total cholesterol, LDL-c, and TG (p < 0.05) reduced in comparison to diabetic animals without treatment (better or similar to n-3 group depending on dose), but did not reach normal levels (in comparison to healthy controls). HDL-c was not different (p > 0.05) among all groups. These reductions were already seen with the lowest dose of 10 mg/kg. On average, the serum levels of the hepatic enzymes ALT and AST were 40% and 60% lower in the BG groups in comparison to diabetic animals without treatment (better results than n-3 group). The group receiving 40 mg/kg reached similar values of healthy controls for ALT; whereas the same result occurred from the dose of 10 mg/kg for AST. The ideal dose, estimated from the mean of all metabolic parameters was approximately 30 mg/kg/day. Regarding the immunological profile, TNF-α significantly decreased in the BG groups compared to controls (p < 0.05), reaching better values than n-3 group and similar to healthy controls. No significant differences were found between the groups in IL-1β or IL-10 (p > 0.05). No histological changes were found in the pancreas, liver, or intestine due to treatment among diabetic animals.

CONCLUSIONS

BG significantly reduced blood glucose as well as serum total cholesterol, LDL-c and TG. There was a hepatoprotective effect due to the reduction in ALT and AST and a reduction in TNF-α, indicating a modulation of the immune response. In general, BG effects were better than n-3 supplement (or at least comparable) depending on the dose.

Metabolomics study of the anti-inflammatory effects of endogenous omega-3 polyunsaturated fatty acids

Low-grade inflammation is usually defined as the chronic production and a low-grade state of inflammatory factors, it often does not have symptoms, and has been associated with neurodegenerative disease, obesity, and diabetes. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) are the precursors of many anti-inflammatory metabolites, such as resolvins and neuroprotectins. It is of interest to study the metabolic profile of endogenous n-3 PUFAs in low-grade inflammatory conditions. To evaluate the protective effects of endogenous n-3 PUFAs on low-grade inflammation with the metabolomics approach, we fed fat-1 mice with an n-6 PUFAs rich diet for a long time to induce a low-grade inflammatory condition. Multi-analysis techniques, including structural analysis using quadrupole time-of-flight mass spectrometry with MS^E mode, were applied in untargeted metabolomics to search for meaningful metabolites with significant variance in fat-1 mice under low-grade inflammation. Following the untargeted metabolomics screening, several meaningful metabolites were selected which were associated with anti-inflammatory effects generated from endogenous n-3 PUFAs for further analysis. The results revealed that the purine metabolism, fatty acid metabolism and oxidative stress response pathways through insulin resistance were involved in anti-inflammatory mechanisms of n-3 PUFA in low-grade inflammatory conditions. For the first time, this study explored the highlighted pathways as contributors to the anti-inflammatory effects of endogenous n-3 PUFAs in low-grade inflammatory conditions.

Low-grade inflammation is usually defined as the chronic production and a low-grade state of inflammatory factors, it often does not have symptoms, and has been associated with neurodegenerative disease, obesity, and diabetes.

Effects of n-3PUFAs on autophagy and inflammation of hypothalamus and body weight in mice

OBJECTIVE

Fat-1 transgenic mice were used as a model to study the effect of endogenous n-3 polyunsaturated fatty acids (n-3PUFAs) on the body weight, inflammatory factors and autophagy proteins in hypothalamus to explore the mechanism of n-3PUFAs inhibiting obesity.

METHOD

The mice were divided into two groups after genotype identification: fat-1 transgenic mice and wild-type mice. The body weight and body length of mice were measured at 14th week, and calculated the Lee 's index. The autophagosome in arcuate nucleus neurons was observed through electron microscopy; the expression of autophagy protein P62, LC3 and ATG7 in hypothalamus were detected and analyzed quantitatively by immunofluorescence and Western blot techniques. The mRNAs of inflammatory factor TNF-α, IL-6, IL-1β, NF-kB, chemokine MCP-1, CCL5, CXCL12, CX3CL1, microglia markers TMEM119, GFAP were detected by real-time fluorescence quantitative PCR.

RESULT

The Lee's index of fat-1 transgenic mice was lower than that of wild-type mice(P < 0.05). The autophagosome of the arcuate nucleus in fat-1 transgenic mice were more than those in wild-type mice, and the expression of autophagy-related protein P62 was significantly decreased (P < 0.05) in hypothalamus of fat-1 transgenic mice, while the expression of autophagy related protein ATG7 was significantly up-regulated (P < 0.05), and the ratio of LC3 II/I was significantly increased (P < 0.05), The results of qPCR showed that the mRNAs of TNF-α, IL-6, IL-1β, NF-kB, MCP-1, CCL5, CXCL12, and GFAP was significantly down regulated (P < 0.05), but CX3CL1 was significantly up-regulated (P < 0.05) in hypothalamus of fat-1 transgenic mice.

CONCLUSION

Fat-1 gene or n-3 PUFAs possesses the function of reducing body weight, which involves the enhancement of autophagy and reduction of inflammatory factor in hypothalamus.

Arachidonic acid in health and disease with focus on hypertension and diabetes mellitus: A review

Arachidonic acid (AA 20:4n-6) is an essential component of cell membranes and modulates cell membrane fluidity. AA is metabolized by cyclo-oxygenase (COX), lipoxygenase (LOX) and cytochrome P450 enzymes to form several metabolites that have important biological actions. Of all the actions, role of AA in the regulation of blood pressure and its ability to prevent both type 1 and type 2 diabetes mellitus seems to be interesting. Studies showed that AA and its metabolites especially, lipoxin A4 (LXA4) and epoxyeicosatrienoic acids (EETs), potent anti-inflammatory metabolites, have a crucial role in the pathobiology of hypertension and diabetes mellitus. AA, LXA4 and EETs regulate smooth muscle function and proliferation, voltage gated ion channels, cell membrane fluidity, membrane receptors, G-coupled receptors, PPARs, free radical generation, nitric oxide formation, inflammation, and immune responses that, in turn, participate in the regulation blood pressure and pathogenesis of diabetes mellitus. In this review, role of AA and its metabolites LXA4 and EETs in the pathobiology of hypertension, pre-eclampsia and diabetes mellitus are discussed. Based on several lines of evidences, it is proposed that a combination of aspirin and AA could be of benefit in the prevention and management of hypertension, pre-eclampsia and diabetes mellitus.

Is There a Role for Bioactive Lipids in the Pathobiology of Diabetes Mellitus?

Inflammation, decreased levels of circulating endothelial nitric oxide (eNO) and brain-derived neurotrophic factor (BDNF), altered activity of hypothalamic neurotransmitters (including serotonin and vagal tone) and gut hormones, increased concentrations of free radicals, and imbalance in the levels of bioactive lipids and their pro- and anti-inflammatory metabolites have been suggested to play a role in diabetes mellitus (DM). Type 1 diabetes mellitus (type 1 DM) is due to autoimmune destruction of pancreatic β cells because of enhanced production of IL-6 and tumor necrosis factor-α (TNF-α) and other pro-inflammatory cytokines released by immunocytes infiltrating the pancreas in response to unknown exogenous and endogenous toxin(s). On the other hand, type 2 DM is due to increased peripheral insulin resistance secondary to enhanced production of IL-6 and TNF-α in response to high-fat and/or calorie-rich diet (rich in saturated and trans fats). Type 2 DM is also associated with significant alterations in the production and action of hypothalamic neurotransmitters, eNO, BDNF, free radicals, gut hormones, and vagus nerve activity. Thus, type 1 DM is because of excess production of pro-inflammatory cytokines close to β cells, whereas type 2 DM is due to excess of pro-inflammatory cytokines in the systemic circulation. Hence, methods designed to suppress excess production of pro-inflammatory cytokines may form a new approach to prevent both type 1 and type 2 DM. Roux-en-Y gastric bypass and similar surgeries ameliorate type 2 DM, partly by restoring to normal: gut hormones, hypothalamic neurotransmitters, eNO, vagal activity, gut microbiota, bioactive lipids, BDNF production in the gut and hypothalamus, concentrations of cytokines and free radicals that results in resetting glucose-stimulated insulin production by pancreatic β cells. Our recent studies suggested that bioactive lipids, such as arachidonic acid, eicosapentaneoic acid, and docosahexaenoic acid (which are unsaturated fatty acids) and their anti-inflammatory metabolites: lipoxin A4, resolvins, protectins, and maresins, may have antidiabetic actions. These bioactive lipids have anti-inflammatory actions, enhance eNO, BDNF production, restore hypothalamic dysfunction, enhance vagal tone, modulate production and action of ghrelin, leptin and adiponectin, and influence gut microbiota that may explain their antidiabetic action. These pieces of evidence suggest that methods designed to selectively deliver bioactive lipids to pancreatic β cells, gut, liver, and muscle may prevent type 1 and type 2 DM.

N-3 polyunsaturated fatty acids attenuates triglyceride and inflammatory factors level in hfat-1 transgenic pigs

BACKGROUND

The consumption of n-3 polyunsaturated fatty acids (PUFAs) is important to human health, especially in cases of cardiovascular disease. Although beneficial effects of n-3 PUFAs have been observed in a number of studies, the mechanisms involved in these effects have yet to be discovered.

METHODS

We generated hfat-1 transgenic pigs with traditional somatic cell nuclear transfer (SCNT) technology. The fatty acid composition in ear tissue of pigs were detected with gas chromatography. The cholesterol, triglycerides (TAG) and inflammation mediators in circulation were investigated.

RESULTS

The hfat-1 transgenic pigs were developed which accumulate high levels of n-3 PUFAs than wild-types pigs. Gas chromatography results demonstrated that the total n-3 PUFAs in the ear tissues of the transgenic founders were 2-fold higher than the wild-type pigs. A lipid analysis demonstrated that the levels of TAG in the transgenic pigs were decreased significantly. The basal levels of the inflammation mediators tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6) in transgenic pigs were inhibited markedly compared with the wild-type pigs.

CONCLUSIONS

These results suggest that n-3 PUFAs accumulation in vivo may have beneficial effects on vascular and hfat-1 transgenic pigs may be a useful tool for investigating the involved mechanisms.