Effect of L-glutamine on obesity and insulin resistance in high-fat diet-induced C57BL/6J mice

AIM:To explore the effect of L-glutamine (Gln) on obesity and insulin resistance in high-fat diet(HFD)-induced C57BL/6J mice. METHODS:Male C57BL/6J mice (n=60) were randomly divided into normal control (NC) group, HFD group, HFD+L-alanine (Ala) group and HFD+Gln group. Each group had 15 mice. The body weight of the mice was recorded weekly. Fasting blood glucose (FBG) of the mice was tested after 12-h fasting only with water-drinking at the end of the 16th week. The mice were sacrificed and epididymal fat pad was measured. The levels of insulin (INS), leptin (LEP), adiponectin (APN) and glucagon-like peptide-1 (GLP-1) were measured by ELISA. The insulin resistance index (IRI) and insulin sensitivity index (ISI) were calculated. RESULTS:Compared with NC group, the body weight, epididymal fat pad weight, and the levels of FBG, INS, IRI and LEP increased significantly in HFD group (P<0.05), while the levels of ISI and APN decreased significantly (P<0.05). Compared with HFD group, the body weight, and the levels of FBG, IRI and LEP decreased significantly in HFD+Gln group (P<0.05), while the levels of ISI and APN increased significantly (P<0.05). No significant difference of serum GLP-1 levels the four groups was observed. CONCLUSION:L-glutamine reduces the body weight and attenuates the insulin resistance of HFD-induced mice.     

Replacing dietary antibiotics with 0.20% l-glutamine in swine nursery diets: impact on intestinal physiology and the microbiome following weaning and transport

Previous research demonstrates that supplementing 0.20% l-glutamine (GLN) in the diets of newly weaned and transported pigs improves growth rate to a similar extent as providing dietary antibiotics (AB). However, research comparing the effects of GLN vs. AB on intestinal physiology and the microbiome is limited. Therefore, the study objective was to compare the effects of supplementing nursery diets with GLN, AB, or no dietary antibiotics (NA) on intestinal physiology and the microbiome of pigs in a production environment following weaning and transport. Mixed-sex piglets (N = 480; 5.62 ± 0.06 kg body weight [BW]) were weaned (18.4 ± 0.2 d of age) and transported for 12 h in central Indiana, for two replicates, during the summer of 2016 and the spring of 2017. Pens were blocked by BW and allotted to one of the three dietary treatments (n = 10 pens/dietary treatment/replicate [8 pigs/pen]): AB (chlortetracycline [441 ppm] + tiamulin [38.6 ppm]), GLN (0.20% as-fed), or NA fed for 14 d. From day 14 to 34, pigs were fed common AB-free diets in two phases. On day 33, villus height:crypt depth tended to be increased (P = 0.07; 7.0%) in GLN and AB pigs vs. NA pigs. On day 33, glucagon-like peptide 2 (GLP-2) mRNA abundance was decreased (P = 0.01; 50.3%) in GLN and NA pigs vs. AB pigs. Crypt depth was increased overall on day 33 (P = 0.01; 16.2%) during the spring replicate compared with the summer replicate. Villus height:crypt depth was reduced (P = 0.01; 9.6%) during the spring replicate compared with the summer replicate on day 33. On day 13, tumor necrosis factor-alpha and occludin mRNA abundance was increased (P ≤ 0.04; 45.9% and 106.5%, respectively) and zonula occludens-1 mRNA abundance tended to be greater (P = 0.10; 19.2%) in the spring replicate compared with the summer replicate. In addition, AB pigs had increased (P = 0.01; 101.3%) GLP-2 mRNA abundance compared with GLN and NA pigs. Microbiome analysis indicated that on day 13, dietary treatment altered the microbiota community structure (P = 0.03). Specifically, the AB pigs tended to be distinct from both the NA and GLN pigs (P = 0.08), and Lactobacillus was increased nearly 2-fold in AB compared with NA pigs (q = 0.04) and GLN pigs (q = 0.22). In conclusion, GLN supplementation tended to improve some morphological markers of intestinal health similarly to AB pigs, while the microbiome composition in GLN pigs was more similar to NA pigs than AB pigs.     

RESEARCH ARTICLE Effects of Central Administration of Glutamine and Alanine on Feed Intake and Hypothalamic Expression of Orexigenic and Anorexigenic Neuropetides in Broiler Chicks

Different amino acids have been shown to affect feed intake when injected directly into the central nervous system of birds. In the present study, we investigated the effects of L-glutamine and L-alanine on feed intake and the mRNA expression levels of hypothalamic neuropeptides involved in feed intake regulation in broiler chicks. L-Glutamine or Lalanine was intra-cerebroventricularly (ICV) administered to 4-d-old broiler chicks and the feed intake were recorded at various time points. Quantitative PCR was performed to determine the hypothalamic mRNA expression levels of neuropeptide Y (NPY), agouti related protein (AgRP), pro-opiomelanocortin (POMC), melanocortin receptor 4 (MC4R) and corticotropin releasing factor (CRF). Our results showed that ICV administration of L-glutamine (0.55 or 5.5 μmol) significantly increased feed intake up to 2 h post-administration period and the hypothalamic NPY mRNA expression levels, while it markedly decreased hypothalamic POMC and CRF mRNA expression levels. In contrast, ICV administration of L-alanine (4 μmol) significantly decreased feed intake for the first 0.5 h post-administration period, and reduced the hypothalamic AgRP mRNA expression levels, while it remarkablely enhanced the mRNA expression levels of MC4R and CRF. These findings suggested that L-glutamine and L-alanine could act within the hypothalamus to influence feed intake in broiler chicks, and that both orexigenic and anorexigenic neuropeptide genes might contribute directly to these effects.     

单根阴离子交换柱法提取L-谷氨酰胺工艺研究

[目的]研究不同影响因素及工艺条件对提取L-谷氨酰胺的影响,为谷氨酰胺的工业化生产提供一种新型分离工艺。[方法]利用单根阴离子交换柱,采用静态吸附试验和动态分离试验研究从酶法合成液中提取谷氨酰胺的各种条件。[结果]模拟液离交分析的最适条件为：树脂201x4,进样流速为3．0BV／h,进样pH值6．5,谷氨酸浓度1．O％。酶反应液处理的工艺条件为：脱色温度40℃,pH值6．5,10．0g/L粉末状活性炭进行二次脱色,15．0mmol／L的Ca2＋添加量来去除样液中PO4^3＋,离交分离条件同模拟液。Gin收率为66．6％、Glu去除率为95．O％。[结论]该研究得到的处理方法简单易行,Gin收率和Glu去除率高,在工业生产中有较好的应用前景。     

谷氨酰胺高效酶法转化条件研究

[目的]研究不同影响因素及工艺条件对酶法生产L-谷氨酰胺的影响。[方法]以安琪酵母为试验菌种,在YEPD培养基中28℃培养24h后进行气流干燥处理,然后进行谷氨酰胺的合成反应,之后测定与计算葡萄糖（谷氨酸）的量、谷氨酸的消耗量以及谷氨酰胺的生成量。[结果]在磷酸盐浓度为0.15mol／L,酶液浓度在80U／ml时,谷氨酸加入量为25g／L,谷氨酰胺的产量最大,提高葡萄糖加入量会增加谷氨酰胺的转化,但利用率明显降低。通过正交试验发现,优化条件与单因素试验结果一致,谷氨酸添加量是最显著的因素,在优化条件下,谷氨酰胺产量达26.8g/L,转化率为91.2％。采用葡萄糖、谷氨酸的分批补料工艺,得到谷氨酰胺的最高产量为33.8g/L。[结论]优化酶法合成谷氨酰胺的工艺条件能够有效降低生产成本。     

L-谷氨酰胺对麻疯树再生不定芽生根效果的影响

[目的]建立促进麻疯树再生不定芽生根的组培体系。[方法]通过在诱导麻疯树再生不定芽分化生根的培养基(MS+0.3 mg/L IBA)中添加一定浓度的L-谷氨酰胺(Gln)来达到促进芽条生根的效果。[结果]在诱导麻疯树再生不定芽分化生根的培养基中添加20 mg/L Gln,可以显著提高芽条的生根率,生根率可达40%~50%。同时,可以在短时间内就获得较高的生根率,显著缩短了获得完整植株的周期。此外,还减少了生根过程中常见的再生植株叶片发黄、容易脱落现象的发生,显著提高了所获得的再生完整植株的质量。[结论]麻疯树生根培养基的最优组合为添加0.3 mg/L IBA和20 mg/L Gln的MS培养基,应用该研究建立的组培体系可显著改善麻疯树再生不定芽的生根效果。     

絮凝、吸附和超滤预处理谷氨酰胺发酵液研究

为进一步纯化和精制谷氨酰胺,采用絮凝、离心、活性炭吸附和超滤等方法对发酵液进行了预处理。实验优化了絮凝的最佳条件,研究了活性炭对色素的吸附能力,尝试了3种超滤膜的去蛋白和脱色效果。结果表明,壳聚糖浓度为250mg/L,壳聚糖和海藻酸钠浓度比为1∶3,p H控制在5左右,温度在25℃左右,搅拌强度为80r/min,絮凝时间为15min,絮凝效果最好,菌体去除率超过97%。用GH-15活性炭对絮凝后的发酵液脱色,脱色率达75%。使用截留分子量为6 000的超滤膜,脱色率进一步提高了43.82%,蛋白去除率为75.33%。