Endogenous biosynthesis of docosahexaenoic acid(DHA)regulates fish oocyte maturation by promoting pregnenolone production

Omega-3 polyunsaturated fatty acids(n-3 PUFAs),particularly docosahexaenoic acid(22:6n-3,DHA),play crucial roles in the reproductive health of vertebrates,including humans.Nevertheless,the underlying mechanism related to this phenomenon remains largely unknown.In this study,we employed two zebrafish genetic models,i.e.,elovl2^(-/-)mutant as an endogenous DHAdeficient model and fat1(omega-3 desaturase encoding gene)transgenic zebrafish as an endogenous DHA-rich model,to investigate the effects of DHA on oocyte maturation and quality.Results show that the elovl2^(-/-)mutants had much lower fecundity and poorer oocyte quality than the wild-type controls,while the fat1 zebrafish had higher fecundity and better oocyte quality than wildtype controls.DHA deficiency in elovl2^(-/-)embryos led to defects in egg activation,poor microtubule stability,and reduced pregnenolone levels.Further study revealed that DHA promoted pregnenolone synthesis by enhancing transcription of cyp11a1,which encodes the cholesterol side-chain cleavage enzyme,thereby stabilizing microtubule assembly during oogenesis.In turn,the hypothalamic-pituitary-gonadal axis was enhanced by DHA.In conclusion,using two unique genetic models,our findings demonstrate that endogenously synthesized DHA promotes oocyte maturation and quality by promoting pregnenolone production via transcriptional regulation of cyp11a1.

Encapsulation of docosahexaenoic acid (DHA) using self-assembling food-derived proteins for efficient biological functions

Docosahexaenoic acid(DHA;22n-6)possesses multiple biological functions, including antioxidant activity and ameliorating hypertriglyceridemia. However, the application of DHA has been limited due to poor aqueous solubility and susceptible to oxidation. Here, ovalbumin(O), myosin(M), 7S soy globulin(S), and β-lactoglobulin(β), hydrolyzed by chymotrypsin, self-assembled into micelles, respectively. Adding incremental DHA to micelles caused endogenous fluorescence quenching of O, M, S, and β micelles, implying successful incorporation of DHA into hydrophobic cores of micelles(O(DHA), M(DHA), S(DHA), and β(DHA)). The results showed that micelles provided spatial stability and improved solubility, and stability against thermal and ultraviolet(UV)light for DHA. The uptake of DHA from M(DHA), β(DHA), O(DHA), and S(DHA)was 3.27-, 3.91-, 2.7-, and 3.95-fold higher, respectively, than that of DHA by Caco-2 cells. Encapsulation in micelles increased DHA aqueous solubility and uptake, which enhanced cellular endogenous antioxidant defense. Meanwhile, increased uptake of DHA was verified by HepG2 cells, and O, M, S, and β micelles were proven to increase DHA uptake to reduce lipid deposition. Our findings strongly support the possibility that O, M, S, and β micelles can be regarded as a carrier for loading DHA.

Fortification of pork loins with docosahexaenoic acid(DHA) and its effect on flavour

Pork is traditionally low in docosahexanoic acid （DHA, C22：6n-3） and deficient in omega-3 fats for a balanced human diet. DHA as triglycerides was commercially prepared from the microalgae Schizochytfium and injected into fresh pork loins. Treatments of a mixed brine control （CON）, 3.1% sunflower oil in mixed brine （SF） and a 3.1% DHA oil in mixed brine （DHA） were injected into pork loins at 10 mL/100 g and grilled at 205℃. After cooking, the CON and SF pork loins contained 0.03 to 0.05 mg DHA/g of pork and the DHA injected loins contained approximately 1.46 mg DHA/g. This also changed the fatty acid profile of omega-6：omega-3 from, 5 to 1 in the CON pork, to a ratio of 1.7 to 1 in DHA pork. The appearance, odor, oxidation rates and sensory taste, as judged by a trained panel, determined the DHA injected meat to be, ＇slightly desirable＇ and gave lower ＇off flavour＇ scores, relative to the CON and SF injected pork. Pork can be fortified with DHA oil to 146 mg/100 g serving, which would meet half the recommended daily omega 3 fatty acid requirements for adult humans and would be desirable in taste.

Fatty Acid Composition and Digestive Enzyme Activities of Rainbow Trout in Response to Dietary Docosahexaenoic Acid(DHA)and Eicosapentaenoic Acid(EPA)During Salinity Acclimation

This physiological study aimed to evaluate the effects of dietary docosahexaenoic acid(DHA)and eicosapentaenoic acid(EPA)on the fatty acid composition and digestive enzyme activities of rainbow trout(Oncorhynchus mykiss)during salinity acclimation.Rainbow trout with an average initial weight of 90.61 g±9.25 g were fed diets with the quantities of DHA and EPA equaling to 0.54%,0.95%,1.40%and 1.79%(abbreviated as DE-0.54,DE-0.95,DE-1.40,and DE-1.79,respectively)for eight weeks,after which the gastric and intestinal fatty acids composition were analyzed.Subsequently,the fish underwent salinity acclimation.On days 1,4,7,and 14 after the freshwater was replaced by seawater and at the end of the 8-week period,gastric and intestinal digestive enzyme activities were determined.The results showed that the gastric and intestinal DHA and EPA contents of the fish were positively correlated to their dietary DHA and EPA levels.Low dietary DHA and EPA levels inhibited the protease activity of rainbow trout.Fish in the DE-0.54 group increased the lipase activity to enhance the utilization of lipids maybe due to the inadequate essential fatty acids for fish in this group.Hence,rainbow trout in the DE-0.54 group failed to maintain suitable activities of digestive enzymes after salinity acclimation.Therefore,a diet with minimum 0.95%DHA and EPA levels is necessary for rainbow trout during salinity acclimation.

Computational Analyses of Docosahexaenoic Acid (DHA, C22:6, n-3) with Alzheimer’s Disease-Causing Amyloid Peptide Aβ1-42 Reassures Its Therapeutic Utility

The accumulation of amyloid β peptide1-42 (Aβ1-42) masses in the brains of Alzheimer’s Disease (AD) patients is associated with neuronal loss and memory deficits. We have previously reported that oral administration of docosahexaenoic acid (DHA, C22:6, n-3) significantly decreases Aβ burden in the brains of AD model rats and that direct in vitro incubation of DHA with Aβ1-42 curbs the progression of amyloid fibrillation. In the present in silico study, we investigated whether DHA computationally binds with amyloid peptides. The NMR solution structures of Aβ1-42 were downloaded from the Protein Data Bank (PDB IDs: 1Z0Q and 2BEG). The binding of DHA to Aβ peptides was assessed by molecular docking using both a flexible and rigid docking system. Thioflavin T (ThT) was used as positive control. The chemical structures of ThT and DHA were modeled and converted to the PDB format using PRODRUG. Drug-like properties of DHA were evaluated by ADME (Absorption, Distribution, Metabolism, and Excretion). DHA was found to successfully dock with Aβ1-42. Computational analyses of the binding of DHA to Aβ1-42, as evaluated by docking studies, further corroborated the inhibitory effect of DHA on in vitro Aβ1-42 fibrillogenesis and might explain the in vivo reduction of amyloid burden observed in the brains of DHA-administered AD model rats demonstrated in our previous study. These computational data suggest the potential utility of DHA as a preventive medication in Aβ-induced neurodegenerative diseases, including AD.

Effect of docosahexaenoic acid on the recovery of motor function in rats with spinal cord injury: a meta-analysis

Objective:Studies have shown that docosahexaenoic acid(DHA)has a beneficial effect in the treatment of spinal cord injury.A meta-analysis was used to study the effect of DHA on the neurological recovery in the rat spinal cord injury model,and the relationship between the recovery of motor function after spinal cord injury and the time and method of administration and the dose of DHA.Data source:Published studies on the effect of DHA on spinal cord injury animal models from seven databases were searched from their inception to January 2019,including PubMed,MEDLINE,EMBASE,the China National Knowledge Infrastructure,Wanfang,VIP,and SinoMed databases.The search terms included“spinal cord injury”“docosahexaenoic acid”,and“rats”.Data selection:Studies that evaluated the influence of DHA in rat models of spinal cord injury for locomotor functional recovery were included.The intervention group included any form of DHA treatment and the control group included treatment with normal saline,vehicle solution or no treatment.The Systematic Review Centre for Laboratory animal Experimentation’s risk of bias assessment tool was used for the quality assessment of the included studies.Literature inclusion,quality evaluation and data extraction were performed by two researchers.Meta-analysis was then conducted on all studies that met the inclusion criteria.Statistical analysis was performed on the data using RevMan 5.1.2.software.Outcome measures:The primary outcome measure was the score on the Basso,Beattie,and Bresnahan scale.Secondary outcome measures were the sloping plate test,balance beam test,stair test and grid exploration test.Results:A total of 12 related studies were included,3 of which were of higher quality and the remaining 9 were of lower quality.The highest mean Basso,Beattie,and Bresnahan scale score occurred at 42 days after DHA treatment in spinal cord injury rats.At 21 days after treatment,the mean difference in Basso,Beattie,Bresnahan scores between the DHA group and the control group was the most significant(pooled MD=4.14;95%CI=3.58–4.70;P<0.00001).In the subgroup analysis,improvement in the Basso,Beattie,and Bresnahan scale score was more significant in rats administered DHA intravenously(pooled MD=2.74;95%CI=1.41–4.07;P<0.0001)and subcutaneously(pooled MD=2.99;95%CI=2.29–3.69;P<0.00001)than in the groups administered DHA orally(pooled MD=3.04;95%CI=–1.01 to 7.09;P=0.14).Intravenous injection of DHA at 250 nmol/kg(pooled MD=2.94;95%CI=2.47–3.41;P<0.00001]and 1000 nmol/kg[pooled MD=3.60;95%CI=2.66–4.54;P<0.00001)significantly improved the Basso,Beattie,and Bresnahan scale score in rats and promoted the recovery of motor function.Conclusion:DHA can promote motor functional recovery after spinal cord injury in rats.The administration of DHA by intravenous or subcutaneous injection is more effective than oral administration of DHA.Intravenous injection of DHA at doses of 250 nmol/kg or 1000 nmol/kg is beneficial.Because of the small number and the low quality of the included studies,more high-quality research is needed in future to substantiate the results.

Synergistic anticancer properties of docosahexaenoic acid and 5-fluorouracil through interference with energy metabolism and cell cycle arrest in human gastric cancer cell line AGS cells

AIM: To explore the synergistic effect of docosahexaenoic acid(DHA)/5-fluorouracil(5-FU) on the human gastric cancer cell line AGS and examine the underlying mechanism.METHODS: AGS cells were cultured and treated with a series of concentrations of DHA and 5-FU alone or in combination for 24 and 48 h. To investigate the synergistic effect of DHA and 5-FU on AGS cells, the inhibition of cell proliferation was determined by MTT assay and cell morphology. Flow cytometric analysis was also used to assess cell cycle distribution, and the expression of mitochondrial electron transfer chain complexes(METCs)?Ⅰ, Ⅱ and Ⅴ in AGS cells was further determined by Western blot analysis. RESULTS: DHA and 5-FU alone or in combination could markedly suppress the proliferation of AGS cells in a significant time and dose-dependent manner. DHA markedly strengthened the antiproliferative effect of 5-FU, decreasing the IC50 by 3.56-2.15-fold in an apparent synergy. The morphological changes of the cells were characterized by shrinkage, cell membrane blebbing and decreased adherence. Cell cycle analysis showed a shift of cells into the G0/G1 phase from the S phase following treatment with DHA or 5-FU(G0/G1 phase: 30.04% ± 1.54% vs 49.05% ± 6.41% and 63.39% ± 6.83%, respectively, P < 0.05; S phase: 56.76% ± 3.14% vs 34.75% ± 2.35% and 25.63% ± 2.21%, respectively, P < 0.05). Combination treatment of DHA and 5-FU resulted in a significantly larger shift toward the G0/G1 phase and subsequent reduction in S phase(G0/G1 phase: 69.06% ± 2.63% vs 49.05% ± 6.41% and 63.39% ± 6.83%, respectively, P < 0.05; S phase: 19.80% ± 4.30% vs 34.75% ± 2.35% and 25.63% ± 2.21%, respectively, P < 0.05). This synergy was also reflected in the significant downregulation of the expression of METCs in AGS cells.CONCLUSION: Synergistic anticancer properties of DHA and 5-FU may involve interference with energy production of AGS cells via downregulation of METCs and cell cycle arrest.

Long-Term Effects of Docosahexaenoic Acid-Bound Phospholipids and the Combination of Docosahexaenoic Acid-Bound Triglyceride and Egg Yolk Phospholipid on Lipid Metabolism in Mice

The bioavailability of docosahexaenoic acid(DHA) and eicosapentaenoic acid(EPA) depends on their chemical forms. This study investigated the long-term effects of DHA-bound triglyceride(TG-DHA), DHA-bound phospholipid(PL-DHA), and the combination of TG-DHA and egg yolk phospholipid(Egg-PL) on lipid metabolism in mice fed with a high-fat diet(fat levels of 22.5%). Male C57BL/6J mice were fed with different formulations containing 0.5% DHA, including TG-DHA, PL-DHA, and the combination of TG-DHA and Egg-PL, for 6 weeks. Serum, hepatic, and cerebral lipid concentrations and the fatty acid compositions of the liver and brain were determined. The concentrations of serum total triglyceride(TG), total cholesterol(TC), high-density lipoprotein cholesterol(HDL-c), and hepatic TG in the PL-DHA group and the combination group were significantly lower than those in the high-fat(HF) group(P < 0.05). Atherogenic index(AI) of the PL-DHA group was significantly lower than that of the combination group(P < 0.05). Hepatic TC level in the combination group was significantly lower than that in the HF group(P < 0.05), but no significant difference was observed between the combination group and the PL-DHA group. Both the PL-DHA and the combination groups showed significantly increased DHA levels in the liver compared with the HF group(P < 0.05). However, there were no obvious increases in the cerebral DHA levels in all DHA diet groups. These results suggest that PL-DHA was superior to the combination of TG-DHA and Egg-PL in decreasing the AI. Long-term dietary supplementation with low amount of DHA(0.5%) may improve hepatic DHA levels, although cerebral DHA levels may not be enhanced.

High Sn-2 Docosahexaenoic Acid Lipids for Brain Benefits, and Their Enzymatic Syntheses: A Review

The normal development and maintenance of central neural functions are highly correlated with the amount of docosahexaenoic acid(DHA;ω-3 fatty acid)accumulated in the brain.DHA incorporated at the sn-2 position of lipids is well absorbed by intestinal mucosa and utilized efficiently in vivo.However,modern consumers have a reduced direct intake of DHA and increased intake of saturated fats or ω-6 fatty acid oils,resulting in behavioral and neurophysiological deficits.To provide an understanding of the integrated beneficial effects of DHA on the human brain,this review introduces the positional difference(sn-2 and sn-1,3 positions)of DHA on a glycerol skeleton in natural fats and oils,and further discusses the possible functional mechanism regarding DHA supplementation and the gut-brain axis.The multiple bidirectional routes in this axis offer a novel insight into the interaction between DHA supplementation,the gut microbiota,and brain health.To achieve high sn-2 DHA in diets,it is suggested that sn-2 DHA lipids be enzymatically produced in more efficient and economical ways by improving the specific activities of lipases and optimizing the purification procedures.These types of diets will benefit individuals with strong needs for sn-2 ω-3 lipids such as infants,children,and pregnant and lactating women.

Moderating effect of synthesized docosahexaenoic acid-enriched phosphatidylcholine on production of Th1 and Th2 cytokine in lipopolysaccharide-induced inflammation

Objective: To evaluate effects of docosahexaenoic acid-enriched phosphatidylcholine(DHAPC) on cytokine production induced by lipopolysaccharide(LPS). Methods: The culture supernatants of splenocytes exposed to DHA-PC along with LPS were harvested to determine the production of Th 1(IFN-kines. Cytokines were m毭 and IL-2) and Th2 [IL-4, IL-5, IL-6 and IL-12/IL-23(p40)] cytoeasured using ELISA. Results: Co-administration of DHAPC with LPS resulted in significantly lower IL-2 expression compared to that observed with administration of only LPS(P<0.01). Treatment with DHA-PC and LPS significantly increased IL-5 expression(P<0.01). Moreover, co-administration of DHA-PC with LPS significantly decreased IL-6 and IL-12/IL-23(p40) expressions compared to that observed with administration of only LPS(P<0.01). Conclusions: Our results suggest that DHA-PC inhibits pro-inflammatory cytokines [IL-2, IL-6 and IL-12/IL-23(p40)] expression on induction of inflammation.

藻油DHA微胶囊制备及稳态化递送技术研究进展

藻油DHA为多不饱和脂肪酸,具有促进大脑生长发育,预防心血管疾病,参与免疫调节等多种生理功能,然而其极不稳定,易受到光、热、水及CO_(2)等因素的影响,导致其氧化、变质。目前,国内外对藻油DHA稳态化递送技术的研究颇多,微胶囊技术是其中一种较为成熟的方法,且应用最为广泛,能够有效增强藻油DHA的递送能力、贮藏稳定性及生物利用度。本文概述藻油DHA的来源、理化性质、生物活性及其递送体系等,重点探讨藻油DHA微胶囊稳态化靶向递送技术,包括藻油DHA微胶囊的制备方法、递送体系、递送机制、影响因素等,旨在为拓宽藻油DHA在食品领域的应用范围,提供一定的理论依据。

微藻破囊壶菌产功能性脂肪酸DHA研究进展

二十二碳六烯酸(DHA)作为人体必需的多不饱和脂肪酸,在维护心血管健康、抗癌、支持视觉和脑功能等方面至关重要。传统的深海鱼油提取DHA方法存在鱼腥味重、工艺繁琐等问题,迫使研究者寻求更为高效、环保的替代方案。破囊壶菌(Thraustochytrids)凭借其生长迅速、低重金属污染以及高DHA含量的特性,成为工业化生产DHA的潜力微生物之一。当前在破囊壶菌发酵生产DHA的过程中,依然需要解决一系列关键问题,包括提高发酵产量、降低成本等。本文旨在全面阐述破囊壶菌发酵生产DHA的研究现状,包括菌株筛选与改良、DHA生物合成途径、遗传转化及代谢工程、发酵控制策略等方面。首先,总结归纳了对野生型菌株的自然筛选和诱变改良等方法,不断提高破囊壶菌中DHA产油量。其次,详细介绍了破囊壶菌DHA合成途径的研究进展,着重分析了生物合成途径中关键辅助因子在DHA生产中的作用。此外,概述了外源DNA传递到破囊壶菌细胞的遗传转化技术的应用现状,为提高其遗传转化效率和稳定性提供重要参考。在DHA代谢调控方面,探讨了氮限制对DHA合成的促进作用以及温度和氧气供应对生产效率的影响。最后,对利用破囊壶菌生产DHA存在的主要瓶颈问题和未来发展趋势进行了总结,以推动其在医药、保健品和食品等领域的广泛应用,实现工业规模下的高效生产。

Docosahexaenoic Acid in Breast Milk Reflects Maternal Fish Intake in Iranian Mothers

To estimate essential fatty acid (FA) and long-chain polyunsaturated fatty acid (LCPUFA) concentrations in early breast milk (BM) in relation to habitual fish intake. BM was collected within 72-hours after delivery from consecutively included mothers, 60 in Guilan (coastal) and 60 in Kermanshah (inland) provinces. Mothers were interviewed to com-plete a food frequency questionnaire. The FA composition was measured with gas chromatography. Mothers in the coastal area had higher intake of fish/seafood. Consumption of saturated fat was higher in Kermanshah and olive intake was higher in Guilan. High fish/seafood intake was associated with higher docosahexaenoic acid (DHA) and lower arachidonic acid (AA)/DHA ratio in BM. There were no differences in linoleic and α-linolenic acid concentrations in BM between the provinces. N-3 FA and DHA concentration were significantly higher in Guilan than Kermanshah, but total n-6 FAs and AA did not differ and were high in both provinces. The ratios of total n-6/n-3 and AA/DHA in BM of mothers from Guilan were significantly lower than those in Kermanshah. The LCPUFA status in BM in two Iranian provinces was generally good and DHA was higher and the AA/DHA was significantly lower in mothers with high fish intake.

Evaluation of the inhibitory effect of docosahexaenoic acid and arachidonic acid on the initial stage of amyloid β1-42 polymerization by fluorescence correlation spectroscopy

Amyloid β(Aβ)1-42 fibrillation is a crucial step in the development of pathological hallmarks, such as neuritic plaques and neurofibrillary tangles, of Alzheimer’s disease (AD). In this study, we evaluated the effects of free docosahexaenoic acid (DHA), an essential brain polyunsaturated fatty acid (PUFA), on the inhibition of Aβ1-42 fibrillation by fluorescence correlation spectroscopy (FCS), a technique capable of detecting molecular movements and interactions in solution. We also examined whether free arachidonic acid (AA), eicosapentaenoic acid (EPA), and metabolites of DHA, including neuroprotectin D1 (NPD1, 10S, 17S-dihydroxy-DHA), resolvin D1 (RvD1, 7S, 8R, 17S-trihydroxy-DHA), and didocosahexaenoyl glycerol (diDHA), affect Aβ1-42 polymerization. The results of the FCS study reveal that DHA and AA significantly reduced the diffusion time of TAMRA (5-carboxytetramethylrhoda-mine)-Aβ1-42 by 28% and 31%, respectively, while EPA, NPD1, RvD1, and diDHA had no effects on diffusion time. These results indicate that DHA and AA inhibited Aβ1-42 polymerization and that their inhibitory effects occurred at the initial stage of Aβ1-42 polymerization. This study will advance the research on PUFAs in preventing AD progression.

Large-Scale Production of Microalgal Lipids Containing High Levels of Docosahexaenoic Acid upon Fermentation of <i>Aurantiochytrium</i>sp. KRS101

In this study, large-scale production of microalgal lipid containing high levels of docosahexaenoic acid (DHA) by fermentation of Aurantiochytrium sp. KRS101 was performed. The microalgal strain yielded productivity of docosahex-aenoic acid (DHA) productivity of 1.08 and 1.6 g/L/d by fermentation at 300-L and 5000-L scale stirrer-type bioreactor. The productivity was significantly enhanced upto 5.6 g/L/d by fermentation at 6000-L scale airlift-type bioreactor, probably due to the reduced shearing force. The microalgal lipid could be efficiently recovered by safe extraction methods such as ethanol extraction, hot water extraction or supercritical fluid extraction, promising commercial potential of the microalgal DHA-rich lipid in the food and feed industry.

巨噬细胞DHA代谢表型在非酒精性脂肪性肝炎发病过程中的作用

非酒精性脂肪性肝炎(NASH)是一种以肝细胞脂肪变、气球样变和小叶内炎症为病理学特征的慢性代谢应激性肝病。本文综述了肠道菌群来源性丁酸通过组蛋白去乙酰化酶(HDAC)/12/15-脂氧合酶(12/15-LOX)/maresin信号途径,对肝脏单核巨噬细胞系统二十二碳六烯酸(DHA)代谢表型的调控作用,以及由此恢复促炎症介质/maresin平衡并促进炎症“程序性消退”,在诱导NASH缓解中的意义。

玉米醇溶蛋白糖基化产物对DHA微胶囊氧化稳定性的影响

为探究糖基化改性玉米醇溶蛋白作为壁材的抗氧化能力,提高藻油在贮藏期间的抗氧化性,利用改性玉米醇溶蛋白作为壁材包埋藻油,对包埋后藻油的储藏稳定性进行分析,并对其货架期进行预测。结果表明,改性玉米醇溶蛋白的最佳工艺条件为糖/蛋白质量比1∶12、反应时间30 min、超声功率400 W,在此条件下glu-zein的抗脂质过氧化能力达到最高,为72.31%。改性后的玉米醇溶蛋白抗脂质过氧化能力、1,1-二苯基-2-三硝基苯肼自由基清除能力、还原能力、羟自由基清除能力、超氧阴离子自由基清除能力等均有显著提高(P<0.05)。将藻油包埋在改性玉米醇溶蛋白中考察藻油的储藏稳定性,在加速氧化期间,其过氧化值、硫代巴比妥酸反应物值均低于裸藻油及未改性玉米醇溶蛋白包埋的藻油。60℃条件下储藏18 d后,glu-zein包埋的藻油POV较未改性玉米醇溶蛋白低3.68 mmol/kg,较裸藻油低39.14 mmol/kg;室温条件下与未包埋藻油货架期相比延长240 d;同时,改性后的玉米醇溶蛋白包埋的藻油二十二碳六烯酸保留率为96.95%。研究结果可为扩大改性玉米醇溶蛋白作为壁材的抗氧化性及递送易受氧气影响的生物活性物质应用提供理论依据。

提高日粮中藻粉添加量对新产牛乳中DHA含量和转化效率的影响

本试验旨在通过提高日粮中包被藻粉添加量,探究头胎新产和经产新产奶牛的牛奶中二十二碳六烯酸(DHA)含量和转化效率随时间变化的规律。试验结果表明,当藻粉添加量从165g/(头·d)提高到400g/(头·d)时,经产新产牛的牛奶DHA含量由5.15mg/100mL升高至10mg/100mL,DHA转化效率则基本保持不变,稳定在9.5%左右;头胎新产牛的牛奶DHA含量由7.76mg/100mL升高至9mg/100mL,而DHA转化效率随藻粉饲喂量增加下降明显,从15.9%降低至9.0%。由此可知,在产犊高峰期间增加经产新产牛藻粉饲喂量可作为一种避免全群牛奶DHA含量降低的手段。而对于头胎新产牛来说,增加藻粉饲喂量对牛奶DHA含量的提升作用有限,且严重降低DHA转化效率,造成原料浪费。因此,建议将头胎新产和经产新产奶牛分开管理,采用不同的藻粉饲喂量,以降低成本。

Protective effects of docosahexaenoic acid against non-alcoholic hepatic steatosis through activating of JAK2/STAT3 signaling pathway

Non-alcoholic fatty liver disease is the most common cause of hepatic dysfunction.In the present study,human normal hepatocyte L02 cells were treated with 50%fetal bovine serum to induce the formation of hepatic steatosis in vitro,and then the cells were treated with docosahexaenoic acid to investigate its protective effect on Non-alcoholic fatty liver disease.Our results showed that 50%of fetal bovine serum significantly induced intracellular lipid accumulation and hepatocyte fatty degeneration within 48 h.The expression level of adipose formation-related genes was significantly up-regulated,such as PPARγ,C/EBPαand SREBP-1;meanwhile,the content of cellular total lipid,total cholesterol and triglycerides were significantly increased after 50%fetal bovine serum treatment.Interestingly,docosahexaenoic acid treatment could inhibit FBS-induced intracellular lipid accumulation in L02 cells and the expression of lipogenic genes.Moreover,docosahexaenoic acid treatment could reduce hepatic steatosis-induced oxidative stress and endoplasmic reticulum stress response,and these responses were shown by the modification of antioxidant enzyme activities and GRP78,CHOP expression.In addition,the results showed that docosahexaenoic acid can activate the JAK2/STAT3 signaling pathway in fatty liver L02 cell;inhibition of JAK2/STAT3 signaling pathway by WP1066 abolished the beneficial effects of docosahexaenoic acid on hepatic steatosis accompanied with the increased expression of lipogenic genes and endoplasmic reticulum stress response.Above all,the present study showed that docosahexaenoic acid can alleviate non-alcoholic hepatic steatosis by activating JAK2/STAT3 signaling pathway.

米糠清蛋白刺槐豆胶多重乳液制备及包埋DHA藻油的研究

以米糠清蛋白和刺槐豆胶为壁材,以二十二碳六烯酸(Docosahexaenoic Acid简称DHA)藻油为芯材制备多重乳液,通过喷雾干燥法制备DHA藻油微胶囊。通过单因素实验确定DHA藻油多重乳液最佳的制备工艺为高速分散机转速12000 r/min、高压均质机压强40 MPa、一级乳液和水相之比为3∶7;DHA藻油微胶囊最佳的成分配比为蛋白质含量0.6%、刺槐豆胶含量0.4%、DHA藻油含量1.5%,pH值为7.0,并对DHA藻油多重乳液的热稳定性和流变学以及DHA藻油微胶囊的贮藏稳定性、微观结构和生物利用率进行研究。试验结果表明:DHA藻油经米糠清蛋白和刺槐豆胶组成的复合壁材包埋后稳定性显著增强;采用复合壁材的DHA藻油微胶囊极大的提高了DHA的生物利用率并且具有良好的热稳定性。