Lipid metabolism is improved by L-carnitinein semi-starved rats fed on high fat diet

AIM: To investigate the effects of exogenous L-carnitine on lipid metabolism in semi-starved rats fed on high fat diet. METHODS: The semi-starved rats were restricted half in calorie intake on high fat diet for 2 week. L-carnitine was supplied at dose of 250 mg/kg·bw. The changes of plasma carnitine concentration, urinary excretion of ketone body, serum lipase activity, muscle carnitine palmitoyl transferase activity, triglyceride secretion and clearance rate were measured. RESULTS: The results showed that the concentration of plasma free carnitine increased significantly in carnitine supplemented rats compared to normal and semi-starved rats.The activities of muscle carnitine palmitoyltransferase and serum lipase were significantly enhanced in carnitine supplemented rats. The triglyceride secretion rate (TGSR) was also improved remarkably by carnitine supplementation. Meanwhile, the urinary excretion of ketone body was reduced significantly in carnitine supplemented rats compared to semi-starved rats. CONCLUSION: It is concluded that carnitine supplementation can significantly increase the plasma concentration of free carnitine and accelerate the lipid metabolism in semi-starved rats fed on high fat diet.     

甜菜碱促进肉鸭生长的作用机理

选用1日龄樱桃谷肉用仔雌鸭864只,随机分成6个组（每组设6个重复）,参试各组按两个剂量水平(0、0.05%)的甜菜碱和三个剂量水平(0、0.06%和0.12%)的蛋氨酸分别组合添加进行2×3析因法设计。研究结果表明,在蛋氨酸相对缺乏的饲料中甜菜碱能高效替代蛋氨酸,甜菜碱比蛋氨酸对改善屠体品质更有效,甜菜碱和蛋氨酸在增重、料重比、胸肌率、腹脂率、肝脏中甜菜碱－高半胱氨酸S－甲基转移酶（BHMT）酶活性和胸肌中肉碱含量上无明显互作效应。结果揭示,甜菜碱可能通过增强甲基代谢,加强了肉碱合成,促进了长链脂肪酸的β-氧化从而达到促进生长,改善胴体的组成。     

肉碱对高产期蛋鸡内脏器官的影响

选用 2 4周龄海兰褐壳蛋鸡分别饲喂添加不同肉碱浓度的日粮 ,试验期 7周 ,测定内脏器官重量 ,内脏器官中肉碱沉积量。试验表明随日粮肉碱浓度的增加 ( 0～ 75mg/kg) ,心脏、肝脏的重量显著下降(P <0 .0 5) ,肝脏、心脏和肾脏中肉碱沉积极显著增加 (P <0 .0 1 ) ,肝脏、心脏和肾脏是肉碱的主要沉积器官。     

Betaine suppresses carnitine palmitoyltransferase I in skeletal muscle but not in liver of finishing pigs

An experiment was conducted to investigate the effect of dietary betaine supplementation on the enzyme activity and mRNA abundance for carnitine palmitoyltransferase I (CPT I) in liver and skeletal muscle of finishing pigs. Forty-eight crossbred barrows and gilts [Duroc × (Seghers × Seghers)] weighing about 55 kg were divided into two dietary treatments, each with three replicates of eight pigs (four barrows and four gilts) per replicate. Pigs were fed a corn–soybean meal basal diet supplemented with betaine at 0 or 1250 mg/kg feed for 42 days. At trial termination, two pigs (one barrow and one gilt) weighing about 90 kg were selected from each replicate (six pigs per dietary treatment) and slaughtered for analyses. The results showed that intramuscular fat content in the longissimus muscle of pigs fed betaine was 23.6% higher than that of controls (P < 0.05), whereas hepatic fat content was not affected with dietary betaine treatment. Muscle-type CPT I (M-CPT I) activity, but not liver-type CPT I (L-CPT I) activity was decreased by betaine supplementation. Furthermore, betaine supplementation reduced M-CPT I mRNA abundance by 14.6% (P < 0.05) but did not affect L-CPT I mRNA abundance. There was a positive correlation between enzyme activity and mRNA abundance for both L-CPT I and M-CPT I (r = 0.67 and r = 0.72 for L-CPT I and M-CPT I, respectively; P < 0.05). The study suggests that betaine may be involved in fat partitioning in pigs by reducing the activity and mRNA abundance of M-CPT I, with a resultant increase in intramuscular fat content.     

甜菜碱促进肉鸭生长的作用机理

选用1日龄樱桃谷肉用仔雌鸭864只,随机分成6个组(每组设6个重复),参试各组按两个剂量水平(0、0.05%)的甜菜碱和三个剂量水平(0、0.06%和0.12%)的蛋氨酸分别组合添加进行2×3析因法设计。研究结果表明,在蛋氨酸相对缺乏的饲料中甜菜碱能高效替代蛋氨酸,甜菜碱比蛋氨酸对改善屠体品质更有效,甜菜碱和蛋氨酸在增重、料重比、胸肌率、腹脂率、肝脏中甜菜碱-高半胱氨酸S-甲基转移酶(BHMT)酶活性和胸肌中肉碱含量上无明显互作效应。结果揭示,甜菜碱可能通过增强甲基代谢,加强了肉碱合成,促进了长链脂肪酸的β-氧化从而达到促进生长,改善胴体的组成。     

Ginsenoside Rg1 improves liver function by regulating fat metabolism in rats with non-alcoholic fatty liver disease

AIM: To investigate whether ginsenoside Rg1 attenuates high-fat diet (HFD)-induced non-alcoho-lic fatty liver disease (NAFLD) by improving β-oxidation. METHODS: SD rats (n=60) were randomly divided into control group (CON), HFD group, low-dose, medium-dose and high-dose ginsenoside Rg1 groups (LDG, MDG and HDG) and positive drug (sodium ursodeoxycholate) treatment group (PDT). High-fat diet was given for 8 weeks to successfully establish an NAFLD model. The animals were treated with the appropriate medications for 4 weeks and 8 weeks after modeling, and sacrificed to collect the liver tissues for observing the pathologic changes with HE staining and for detecting liver functions and lipid levels. The expression of hepatic acyl-CoA synthetase 1 (CoASH1), carnitine acyltransferase I (CATI) and acyl-CoA oxidase 1 (ACOX1) at mRNA and protein levels was determined by RT-PCR and Western blotting. RESULTS: After 4-week treatment, the fatty infiltration of the liver tissues in PDT group, LDG group and MDG group was not attenuated except HDG group. After 8 weeks of treatment, a small number of fat particles was observed in PDT group and LDG group, while no infiltration of lipid droplet was found in MDG group and HDG group. Compared with HFD group, the levels of AST, ALT, AKP, TC, TG and LDL-C were significantly decreased after 4-week treatment in PDT group, LDG group, MDG group and HDG group (P<0.05), these indexes were further reduced after 8-week treatment. After 4-week treatment, HDL-C was significantly increased in the 4 treatment groups and almost restored to the level of CON group after 8-week treatment. The levels of CoASH1, CACTI and ACOX1 in the liver tissue of the 4 treatment groups were significantly increased after 4-week treatment (P<0.05) and much improved after 8-week treatment, and those in MDG group and HDG group were better than those in PDT group (P<0.05).CONCLUSION: Ginsenoside Rg1 regulates β-oxidation-related enzymes to improve the fat metabolism, thus playing a therapeutic role in liver injury in the rats with NAFLD.     

The effect of 5-aminoimidazole-4-carboxamide ribonucleoside （AICAR） on fatty acid oxidation in hepatocytes isolated from neonatal p~glets

In the present study, the effect of 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) on long-chain fatty acid oxidation by hepatocytes isolated from suckled neonatal pig liver (a low ketogenic and lipogenic tissue) was tested. Incubation of hepatocytes with AICAR (0.5 mM) in the presence of 1 mM of carnitine and 10 mM of glucose for 1 hour at 37°C had no significant effect on total [1-14C]-palmitate (0.5 mM) oxidation (14CO2 and 14C-Acid soluble products (ASP)). Consistent with the fatty acid oxidation, carnitine palmitoyltransferase I activity and inhibition of its activity by malonyl-CoA (10 μM) assayed in cell homogenate also remained constant. However, addition of AICAR to the hepatocytes decreased 14CO2 production by 18% compared to control (p < 0.06). The reduction of labeled carboxylic carbon accumulated in CO2 caused a significant difference in distribution of oxidative products between 14CO2 and 14C-ASP (p < 0.03) compared with the control. It was also noticed that acetyl-CoA carboxylase (ACC) was increased by AICAR (p < 0.03), indicating that ACC might drive acetyl-CoA toward fatty acid synthesis pathway and induce an increase in distribution of fatty acid carbon to 14C-ASP. Addition of insulin to hepatocyte incubations with AICAR did not change the oxidative product distribution between CO2 and ASP, but further promoted ACC activity. The increased ACC activity was 70% higher than in the control group when citrate was absent in the reaction medium and was 30% higher when citrate was present in the medium. Our results suggest that AICAR may affect the distribution of metabolic products from fatty acid oxidation by changing ACC activity in hepatocyte isolated from suckled neonatal piglets; however, the basis for the increase in ACC activity elicited by AICAR is not apparent.     

Chemical form of dietary l‐Carnitine affects plasma but not tissue Carnitine concentrations in male Sprague–Dawley rats

In Experiment 1, rats (n = 54) were randomly assigned to control or one of the four sources of l ‐Carnitine supplemented at either 100 or 200 μmol/kg/day and were allowed to acclimate for 14 days. Following a 12‐h fast, plasma samples were obtained at 0, 5, 10, 15, 30, 60, 120, 240, 480 and 720 min after l ‐Carnitine feeding and assayed for free l ‐Carnitine concentration. Plasma‐free l ‐Carnitine levels were affected by time after treatment intake (p < 0.0001) and l ‐Carnitine source (p < 0.0001). The time × source interaction was not statistically significant (p = 0.99). In Experiment 2, rats (n = 54) were randomly assigned to control or one of the four sources of l ‐Carnitine at either 100 or 200 μmol/kg/day and were acclimated as in experiment 1. Rats were sacrificed 120 min after feeding. Samples of liver and skeletal muscle were obtained and assayed for free l ‐Carnitine concentration. Neither skeletal muscle (p = 0.44) or liver (p = 0.59) tissue concentrations of l ‐Carnitine were affected by any l ‐Carnitine source as compared with the control. We conclude that some differences exist in plasma concentrations of free l ‐Carnitine following ingestion of different chemical forms of l ‐Carnitine. It is unclear if these differences in the circulating concentration of free l ‐Carnitine translate into any physiological differences for the animal. In this study, chemical form of l ‐Carnitine had no effect on skeletal muscle or liver tissue concentrations of l ‐Carnitine in young male Wistar rats.     

甜菜碱对猪肉品质的影响及机理探讨

 48头60kg杜长大三元杂交猪分成对照和试验2个处理组,每个处理设3个重复栏,每栏8头猪。对照组饲喂不含甜菜碱的饲粮,试验组饲喂含1000mg/kg甜菜碱的饲粮。结果表明,与对照组相比,饲粮中添加1000mg/kg甜菜碱使试验组猪的胴体脂肪率降低了18.27%(P<0.01),胴体瘦肉率提高了5.71%(P<0.05);使试验组猪背最长肌中肌红蛋白、肌内脂肪和肌苷酸含量分别提高了14.88%(P<0.05)、17.66%(P<0.05)和21.79%(P<0.05);使试验组猪肝脏中甜菜碱-高半胱氨酸甲基转移酶的总活力和比活力分别提高了16.33%(P<0.01)和15.63%((P<0.01);使试验组猪肝脏中游离肉碱的含量提高了16.50%(P<0.05);使试验组猪肌肉中酸不溶肉碱的含量以及酸不溶肉碱与游离肉碱比例分别提高了35.21%(P<0.01)和29.41%(P<0.05)。