【作者】 江敏；

【导师】 阮征；

【作者基本信息】 南昌大学 ， 营养与食品卫生学， 2015， 硕士

【摘要】 婴幼儿时期小孩由于自身消化生理功能尚未发育成熟,当断奶或食物等因素变化时就会导致机体肠道产生应激、破坏肠道功能,致使机体对外源养分和能量摄入不足,严重制约着机体的健康发育。由于仔猪断奶时的生理学特征和营养代谢特点与婴幼儿非常接近,因此本研究选用断奶仔猪作为试验动物模型。通过添加不同剂量色氨酸到断奶仔猪低蛋白日粮中,分析了添加色氨酸后不同时间段断奶仔猪生长性能、血生化指标、抗氧化酶活性及基因水平、游离氨基酸含量、色氨酸分解代谢相关酶含量和氨基酸转运载体表达等变化,探讨色氨酸对断奶仔猪肠道损伤的保护作用。该研究结果不仅对促进仔猪健康生长获取更好的优质肉品质有非常重要的意义,而且对改善婴幼儿的营养供给也具有一定的参考价值。方法:选用体重相近的6.88±0.205 kg的三元杂交(杜洛克×长白×大约克)生长猪42头,随机分成6组,单栏饲养。对照组饲喂基础日粮,试验组分别为添加0.1%和0.2%色氨酸的基础日粮,自由采食和饮水,每天记录采食量和体重。预实验3d后进行正试试验,试验期共14d,分别在第8d和15d早上宰杀取样,宰杀前禁食12个小时。实验结果:(1)给断奶仔猪添加适量色氨酸7天后能提高(P<0.05)采食量和体重,降低(P<0.05)血清胆固醇(cholesterol,CHO)、低密度脂蛋白胆固醇(low density lipoprotein,LDL)、甘油三脂(triglyceride,TG)和尿素氮(Urea N)浓度,增加(P<0.05)白蛋白(albumin,ALB)和葡萄糖(glucose,GLU)浓度。添加适量色氨酸14天后能提高(P<0.05)采食量、体重和料肉比,增加(P<0.05)血清碱性磷酸酶(alkaline phosphatase,ALP)活性和ALB浓度,减少(P<0.05)血清中丙氨酸氨基转换酶(alanine aminotransferase,ALT)活性和CHO、Urea N、TG、总胆红素(total bilirubin,TBIL)、LDL和HDL浓度。(2)给断奶仔猪添加适量色氨酸7天后能提高(P<0.05)血清总抗氧化能力和氧化物歧化酶(Superoxidedismutas,SOD)活性,降低(P<0.05)丙二醛(Malondialdehyde,MDA)浓度以及增加(P<0.05)空肠铜锌超氧化物歧化酶(copper-and zinc-containing superoxide dismutase,CuZnSOD)、锰超氧化物歧化酶(manganese-containing superoxide dismutase,MnSOD)和谷胱甘肽过氧化物酶4(glutathione peroxidase 4,GPx4)及回肠CuZnSOD、MnSOD、谷胱甘肽过氧化物酶1(glutathione peroxidase 1,GPx1)和GPx4表达。添加适量色氨酸14天后能提高(P<0.05)血清谷胱甘肽过氧化物酶(GlutathionePeroxidase,GSH-Px)活性,降低(P<0.05)MDA浓度,以及增加(P<0.05)空肠MnSOD和回肠GPx4表达。说明给断奶仔猪添加色氨酸可以提高其血清抗氧化能力和增加肠道抗氧化酶基因的表达。(3)给断奶仔猪添加适量色氨酸7天后能增加(P<0.05)血清游离氨基酸的含量,提高(P<0.05)肝色氨酸2,3-双加氧酶(Tryptophan 2,3-dioxygenase,TDO)和空肠吲哚胺2,3-双加氧酶(Indoleamine 2,3-dioxygenase,IDO)活性以及上调(P<0.05)空肠ATB0,+、4F2hc、ASCT2和B0AT1表达。添加适量色氨酸14天后能增加(P<0.05)血清游离氨基酸含量和空肠ATB0,+和4F2hc表达。说明添加色氨酸能增加断奶仔猪蛋白质沉积,为机体的快速生长发育提供必要的物质来源。结论:低蛋白日粮中添加适当水平的色氨酸能够提高断奶仔猪生长性能,增强抗氧化能力,促进机体蛋白质沉积。色氨酸的抗氧化作用可以通过上调肠道抗氧化酶基因mRNA水平来实现。色氨酸可以通过上调氨基酸转运载体表达来增加蛋白沉积,但对于氨基酸转运载体的影响机制更为复杂,有待于进一步的探讨。更多还原

【Abstract】 Since digestive physiology has not yet mature in infant, infants often show a series of negative phenomena after weaning or food changes that can lead to intestinal stress and damage intestinal function. These changes will result in body with lacking adequate intake of nutrients and energy and seriously restricts the healthy development of the body. In post-weaning pigs, an experimental model is considered as more relevant for human physiological characteristics and nutritional metabolism characteristics. Thus we select the weaned piglets as experimental animal models in this study. The present study was conducted to analyze the changes of weaned piglets’ some indexes at different stages with tryptophan supplementation,including the growth performance, the serum biochemical indexes, the activity of antioxidative enzymes, the levels of mRNA and protein, the content of free amino acids and catabolic enzymes of tryptophan, the expression of amino acid transporter.It aimed to explore the protective effect of tryptophan on intestinal injury of weaned piglets. The results of ths study not only has very important significance to promote healthy piglets growth and obtain better quality of meat quality, but also have certain reference value to improve infant nutrition.Methods: A total of 42 piglets(offspring of Duroc × Landrace ×Yorkshire) with body weight(BW) of 6.88±0.205 kg were weaned in 21 days from birth and were assigned randomly to three treatment groups(n = 7 per group). In control group, the piglets were fed on a corn and soybean meal-based diet(containing 0.1 % Trp),whereas Trp groups(0.1 or 0.2 % Trp) were fed with the basal diet plus 0.1 or 0.2 %Trp, respectively. At the end of the experiment, we obtained the blood samples of the weaned piglets at 8:00 a.m on the 8th and 15 th days after 12 h lasting.(1) The results showed that a moderate amount supplementation of Trp in diet significantly increased(P < 0.05) the ADG and ADFI of the weaned piglets in 7d.Trp supplementation increased(P < 0.05) the contents of glucose and albumin while decreased the content of cholesterol. Supplying Trp decreased(P < 0.05) the contents of urea N and triglyceride. In addition, a moderate amount supplementation of Trpin diery significantly increased(P < 0.05) the ADG, ADFI and F:G of piglets in 14 d.Trp supplementation increased(P < 0.05) the activity of ALP and the content of ALB.Trp decreased the activity of ALT and the contents of CHO, Urea N, TG, TBIL, LDL and HDL.(2)The results showed that supplying a moderate amount of Trp in diet significantly increased(P < 0.05) the T-AOC and superoxide dismutase(SOD)activity, and reduced(P < 0.05) Malondialdehyde(MDA) level in 7d. Trp increased total antioxidant capacity(P < 0.05). Furthermore, dietary Trp up-regulated(P < 0.05)the mRNA levels of Copper- and zinc-containing superoxide dismutase(CuZnSOD),Manganese-containing superoxide dismutase(MnSOD) and glutathione peroxidase 1(GPx1) in jejunum and CuZnSOD, MnSOD, GPx1, and Glutathione peroxidase 4(GPx4) in ileum. In addition, supplying a moderate amount of Trp in diet resulted in increased glutathione peroxidase(GSH-Px) activity and reduced malondialdehyde(MDA) content in 14d(P < 0.05). In addition, dietary Trp not only up-regulated the mRNA levels(P < 0.05), but also increased the protein expression level of manganese-containing superoxide dismutase(MnSOD) and glutathione peroxidase 4(GPx4) in the jejunum and ileum of weaned piglets(P < 0.05), respectively.Collectively, the results indicated that Trp supplementation could improve the serum antioxidant capacity and increase intestinal antioxidant enzyme gene expression in weaned piglets.(3) The results showed that supplying a moderate amount of Trp in diet significantly increased(P < 0.05) the content of free amino acids, TDO and IDO activity in liver and jejunum in 7d, respectively. What’s more, Trp supplementation could increased(P < 0.05) ATB0, +, 4F2 hc, ASCT2 and B0AT1 expression in jejunum.a moderate amount supplementation of Trp in diet could significantly increase(P < 0.05) the content of free amino acids and ATB0,+, 4F2 hc expression in jejunum. Above all, the results indicated that Trp supplementation could increase weaned piglets’ protein deposition and provide the necessary material of the body source to rapid growth and development.Conclusion: Supplying a moderate amount of Trp in the low protein diet canimprove the growth performance, antioxidant capacity and body protein deposition of the weaned piglets. The antioxidant effect of tryptophan can be realized by increasing the expression levels of the antioxidant enzyme gene mRNA in intestine.Tryptophan can increase protein deposition through expressing the amino acid transport carrier. However, the mechanism of the amino acid transport carrier is much more complicated and needs to be further discussed.更多还原