Urinary amino acid excretion and plasma amino acid concentration in dogs fed crystalline amino acid diets

Plasma amino acid concentrations and urinary amino acid excretion were exanined in Pointer puppies fed a crystalline amino acid diet. Amino acids accounted for only a small percentage (1.7%) of total urinary nitrogen (N). In addition, amino acid excretion accounted for a low percentage (<1%) of amino acid intake. A complete urinary amino acid profile is presented. Free amino acid concentrations in plasma were examined at 0, 45, 90, 150, 210 and 300 minutes after feeding. Both the amount of time required for an ingested amino acid to reach its highest plasma concentration and the length of time plasma amino acid concentration remained elevated depended upon the amino acid in question. These data provide useful information for determining the optimal postprandial time for bleeding dogs fed a purified diet.     

The design and validation of a diet for studies of amino acid metabolism in adult humans

A dietary protocol developed for use in studies of amino acid and protein metabolism is reported in detail. The diet consisted of a mixture of free amino acids, an amino nitrogen-free liquid formula and protein-free cookies. Energy requirement for a group of adult men (n=10) was determined by multiplying each individual's resting metabolic rate, measured by indirect calorimetry, by a factor of 1.7. Subjects maintained a constant weight while consuming the experimental diet and had few complaints regarding palatability during a nine day study period. No significant variation (P=0.69) was evident over a six hour period in measurements of ¹³CO₂ enrichment in the breath of subjects (n=4) consuming small hourly meals of the diet. Dietary adaptation to a constant level of ¹³C enrichment in breath CO₂ with this dietary protocol was accomplished in a short period of time as shown by the lack of change in the mean (±SD) ¹³C enrichments of 0.02764±0.00084, 0.02818±0.00067 and 0.02812 ±0.00062 atoms percent enrichment in subjects (n=7) on days 3, 6 and 9 of the dietary period, respectively. The small within subject variation in repeated ¹³CO₂ enrichment measurements indicates the reliability of the dietary protocol in studies where a steady isotope background is essential. This dietary protocol provides a constant and stable metabolic milieu for studies of amino acid metabolism, especially, for those involving the use of stable isotopes.     

氨基酸复合制剂改善生长发育的动物实验研究

目的:研究氨基酸复合制剂对仔鼠生长发育的影响。方法:采用雄性SD仔鼠每天经口给予氨基酸复合制剂,剂量分别为0、250、5001、000 mg/kg体重,并于第1天、第14天、第28天、第42天测量大鼠的体重、身长,计算每周食物利用率和总食物利用率,结果:与对照组相比,氨基酸复合制剂各剂量组大鼠在体重、身长和食物利用率等生长发育指标差异有显著性,结论:氨基酸复合制剂具有促进仔鼠生长发育作用。     

Growth and composition of brain myelin lipid in rats raised on restricted casein and soy protein diets

Studies were made in weanling and post-weanling rats to compare the effects of restricted dietary levels (8%) of casein (CS) and soy protein (SP) on the lipid composition of brain myelin, isolated by discontinuous sucrose density gradient ultracentrifugation. Diets containing normal levels (25%) of SP and CS (control), were also investigated. With the restricted protein diets, but not the 25% SP diet, there were significant reductions in the quantities of myelin, and of myelin lipid classes, relative to control. These deficits, including those of growth and body weight (but not brain weight), were greater at weaning than at 6 weeks of age. The severity of the deficits at each age, differed very significantly, depending on the type of dietary protein fed. Concerning the individual phospholipids at weaning, the restricted protein diets resulted in significantly lower values relative to control; these values were more depressed with the 8% SP than with 8% CS diet. The results were explained on the basis of a possible greater amino acid imbalance in the low protein SP diet than the corresponding CS diet.     

挥发性有机物对小鼠脑组织形态学和氨基酸类递质的影响

目的通过挥发性有机物(VOCs)对小鼠脑组织中递质类氨基酸含量的影响,探讨VOCs对小鼠神经系统的毒性。方法采用静式吸入染毒,小鼠亚急性暴露于挥发性有机物,设置对照、低(甲醛1.5mg/m3;VOCs20mg/m3)、中(甲醛4.5mg/m3;VOCs60mg/m3)、高浓度暴露组(甲醛13.5mg/m3;VOCs180mg/m3),染毒结束后,做脑组织常规病理,采用高效液相色谱法测定小鼠脑组织(皮质和海马)氨基酸类递质[包括兴奋性氨基酸类递质谷氨酸(Glu)、门冬氨酸(ASP);抑制性氨基酸类递质氨基丁酸(GABA)、甘氨酸(Gly)]含量。结果暴露组小鼠脑组织皮质和海马兴奋性氨基酸类递质含量随染毒浓度增加而降低,而抑制性氨基酸类递质含量随染毒浓度增加而增加。脑组织病理表现为VOCs暴露组神经元变性坏死。结论挥发性有机物引起小鼠学习记忆能力下降和麻醉作用。     

高脂、高蛋白饮食对幼年大鼠氧化应激的影响

目的:探讨高脂、高蛋白饮食对幼年大鼠氧化应激的影响。方法:5~6周龄雄性Wistar大鼠随机分为对照组、高脂组和高蛋白组,分别用基础饲料、高脂饲料和高蛋白饲料喂养12周。于第6周和第12周测定血清总超氧化物歧化酶(T-SOD)、过氧化氢酶(CAT)、丙二醛(MDA)和谷胱甘肽(GSH)水平。结果:与对照组比较,第6周和第12周时,高脂组和高蛋白组大鼠体脂含量明显增加(P<0.05),血清CAT活性明显下降(P<0.01)。结论:短期和长期高脂或高蛋白饮食能增加幼年大鼠体脂含量,并增加机体氧化应激水平。     

高脂饲料诱导对大鼠血脂的影响

目的比较分析两种不同高脂饲料对大鼠血脂的影响,为建立合理而实用的高脂血症动物模型提供依据。方法 Wistar大鼠30只,按体重随机分为对照组(喂饲基础饲料),高脂配方1组和高脂配方2组,每组各10只,实验期间每周记录一次大鼠体重,每两周检测一次血脂,实验周期为6周。结果高脂饲料诱导6周后,高脂配方1组大鼠的血清总胆固醇(TC)和低密度脂蛋白胆固醇(LDL-C)分别比对照组升高了1.4倍和2.2倍(P<0.01),血清高密度脂蛋白胆固醇(HDL-C)水平比对照组降低了22.2%(P<0.01),血清甘油三酯(TG)水平与对照组无显著差异(P>0.05);高脂配方2组大鼠的血清TC和LDL-C分别比对照组升高了11.5倍和5.7倍(P<0.01),血清TG和HDL-C水平分别比对照组降低了39.7%和34.6%(P<0.01)。结论两种高脂饲料诱导均可建立大鼠高胆固醇血症模型,但均不能显著升高大鼠血清TG水平。     

复合氨基酸片对四氯化碳肝损伤保护作用的实验研究

目的：探讨复合氨基酸片（谷氨酰胺、精氨酸、甘氨酸和L-半胱氨酸）对四氯化碳（CCl4）肝损伤的保护作用。方法：将40只ICR小鼠随机分成阴性对照组、CCh模型组及490mg、980nag／（kgb．w）两个剂量组,剂量组每天灌胃给予复合氨基酸片,阴性对照组和CCIn模型组给予双蒸水。30d后,CCl4模型组及剂量组以5ml／（kgb．w）的剂量一次性经口给予色拉油配置的0．5％CCl4,24h后处死所有小鼠,测定血清丙氨酸转氨酶（ALT）、天冬氨酸转氨酶（AST）水平,取肝脏左叶进行组织病理学检查。结果：980mg／（kgb．w）剂量组的ALT、AST水平降低,与cch模型组比较,有极显著性差异（P〈0．01）;980mg／（kgb．w）剂量组发生肝细胞坏死的病变程度减轻,肝细胞坏死评分降低,与CCl4模型组比较,有极显著性差异（P〈0．01）。结论：复合氨基酸片对CCl4肝损伤具有辅助保护作用。     

全氟辛烷磺酸对大鼠脑组织氨基酸类神经递质和谷氨酰胺合成酶的影响

目的探讨全氟辛烷磺酸(PFOS)与大鼠中枢神经系统兴奋性氨基酸和谷氨酰胺合成酶(GS酶)的剂量反应关系。方法将20只成年雄性Wister大鼠随机分为4组(对照组、4个染毒组)每组5只。大鼠染毒PFOS(12.5、25、50mg/kg)5天后,对照组给予等体积的2%吐温-80溶液,应用高效液相色谱法测定脑组织氨基酸类神经递质及谷氨酰胺合成酶的改变。结果与对照组比较,大鼠自发活动能力下降;50mg/kg体重组海马谷氨酸含量显著降低,25和50mg/kg体重组皮质谷氨酸含量显著降低;随着染毒剂量的增加海马GS酶活性增加,其中12.5mg/kg剂量组和25mg/kg剂量组明显高于对照组(P<0.05)。结论氨基酸类神经递质含量的改变是PFOS神经毒性的机制之一。     

Lipoic acid increases the expression of genes involved in bone formation in mice fed a high-fat diet

Antioxidant lipoic acid (LA) has been reported to have a potential prophylactic effect on bone loss induced by high-fat diet (HFD). The aim of this work was to examine the hypothesis that LA decreases bone resorption-related gene expression and increases bone formation-related gene expression in HFD-fed mice, preventing a shift in the bone metabolism balance toward resorption. Male C57BL/6 mice were fed a normal diet, HFD, or HFD plus 0.1% LA for 12 weeks. The bone metabolism-related genes differentially expressed between mice fed HFD and those fed HFD supplemented with LA were identified through complementary DNA microarray. The supplemental LA significantly increased bone mineral density and bone antioxidant capacity in mice fed HFD (P < .05). Compared with the HFD-fed mice, LA induced the decreased expression of genes associated with bone resorption, such as Mmp9 (1.9-fold) and Ctsk (2.3-fold), and increased those genes associated with bone formation, such as Col1a1 (1.3-fold) and Alp1 (1.5-fold). Furthermore, LA upregulated many genes involved in the Igf signaling pathway, such as Igf-1 (increased 1.7-fold), and downregulated genes involved in the p53 apoptotic pathway, such as p53 (decreased 2.3-fold), thus attenuating the HFD-induced inhibition of bone formation. Lipoic acid induced upregulation of Il12a (2.1-fold) and downregulation of Tgfbr1 (4.3-fold) and Il17a (11.3-fold), which may reduce bone resorption. In summary, LA supplementation during HFD could affect bone density, altering gene expression.     

休克大鼠血管外膜阳离子氨基酸运体表达

目的观察败血症休克大鼠主动脉外膜阳离子氨基酸转运体(CAT-1、CAT-2B)和诱导型一氧化氮合酶(iNOS)基因表达。方法雄性Wistar大鼠盲肠结扎并穿孔复制败血症休克模型。逆转录-聚合酶链(RT-PCR)方法测定诱导型一氧化氮合酶(iNOS)、CAT-1、CAT-2B mRNA表达水平。结果败血症休克大鼠表现为严重的心功能降低、低血糖和高乳酸血症。血管外膜CAT-1、CAT2B、和iNOS的mRNA水平均比假手术组明显上调(均P<0.01)。结论败血症休克时血管外膜阳离子氨基酸转运体和诱导型一氧化氮合酶基因表达上调。     

Effect of long-term sucrose diet on the reproduction and survival of spiny mice (Acomys cahirinus)

Pairs of spiny mice (Acomys cahirinus), maintained on a 50% sucrose diet in two experiments lasting 18 or 8 months, gained less weight and exhibited a greater mortality rate of both parents, and pups, than mice kept on regular or fat-rich diets. According to the number of pups born and number of productive pairs, the sucrose-fed mice were also less fertile. The litter size and the number of pups born per productive pair, were slightly but not significantly lower. These findings are discussed against the background of metabolic and pathologic changes induced in rodents maintained on sucrose-rich diets.     

Absorptive behavior of oligo-L-methionine and dietary proteins in a casein or soybean protein diet: porto-venous differences in amino acid concentrations in unrestrained rats

In a low casein methionine-deficient diet, supplementation with oligo-L-methionine (OM) has a similar improvement on rat growth to supplementation of free L-methionine. Rat growth is little improved, however, when OM is added to a low soybean protein isolate (SPI) diet. To evaluate the mechanisms of the different effects of OM supplementation, we observed intestinal absorption of OM added to either an 8 g/100 g casein diet or an 8 g/100 g SPI diet. Using portal and venous cannulated rats under unrestrained conditions, we evaluated OM absorption by subtracting methionine porto-venous differences after feeding the diets without OM from the values after feeding the diets with 3% added OM. OM absorption was faster after feeding the casein-based diet than after the SPI-based diet during the initial stages of the experiment only, but throughout the experiment there were greater increments of methionine concentrations in both portal and venous blood after the casein-based diet than after the SPI-based diet. We also discovered that amino acids from the dietary casein were absorbed faster than those from SPI, using the porto-venous difference of isoleucine as an indication. The larger increment of methionine concentrations in the blood after feeding of OM with a casein diet and the rapid absorption of amino acids from casein may result in much growth improvement in rats.     

The effect of ketogenic diet in an animal model of autism induced by prenatal exposure to valproic acid

Objectives: Autism spectrum disorder (ASD) is characterized by impairments in social interaction and communication, and by restricted repetitive behaviors and interests. Its etiology is still unknown, but different environmental factors during pregnancy, such as exposure to valproic acid (VPA), are associated with high incidence of ASD in children. In this context, prenatal exposure to VPA in rodents has been used as a reliable model of ASD. Ketogenic diet (KD) is an alternative therapeutic option for refractory epilepsy; however, the effects of this approach in ASD-like behavior need to be evaluated. We conducted a behavioral assessment of the effects of KD in the VPA model of autism.

Methods: Pregnant animals received a single-intraperitoneal injection of 600 mg/kg VPA, and their offspring were separated into four groups: (1) control group with standard diet (C-SD), (2) control group with ketogenic diet (C-KD), (3) VPA group with standard diet (VPA-SD), and (4) VPA group with ketogenic diet (VPA-KD).

Results: When compared with the control group, VPA animals presented increased social impairment, repetitive behavior and higher nociceptive threshold. Interestingly, the VPA group fed with KD presented improvements in social behavior. These mice displayed higher scores in sociability index and social novelty index when compared with the SD-fed VPA mice.

Discussion: VPA mice chronically exposed to a KD presented behavioral improvements; however, the mechanism by which KD improves ASD-like features needs to be further investigated. In conclusion, the present study reinforces the potential use of KD as a treatment for the core deficits of ASD.     

高蛋氨酸饲料对大鼠氨基酸代谢的影响

目的：研究高蛋氨酸饲料对大鼠生长及体内蛋白质、氨基酸代谢的影响。方法：SD大鼠20只，随机分为两组，即高蛋氨酸组（M组）和对照组（C组）各10只。M组每天给予含3％蛋氨酸的饲料，动态测量体重，分别在0、4、8、12周眼眶取血测血清氨基酸，并在12周处死动物，测肝的游离氨基酸含量。结果：高蛋氨酸在4周时，即出现高同型半胱氨酸血症、高蛋氨酸血症；12周时血清苏氨酸、缬氨酸、亮氨酸、苯丙氨酸含量明显下降，脯氨酸、 精氨酸和丙氨酸血清含量均有显著增高。肝内七种必需氨基酸含量实验组均显著高于对照组，而非必需氨基酸则实验组含量明显低于对照组。同时，实验组大鼠体重增长缓慢。结论：高蛋氨酸饲料能影响血清、肝的游离氨基酸含量，抑制大鼠生长。