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1.
脂肪酸的从头合成发生在肝脏,脂肪组织的生长以及后来的肥胖依赖于以脂蛋白形式转运的血浆甘油三酯。在生长禽VLDL(极低密度脂蛋白)是甘油三酯的主要运输形式,要降低肥胖程度就要通过调节VLDL代谢。现在以腹部脂肪含量和血浆VLDL浓度为标准对脂肪品系和瘦肉品系家禽进行选择,而肝脏的生脂作用和脂肪组织中LPL活性在这两个品系中的差异不显著。当肝脏脂肪合成量大于V.LDL的分泌,甘油三酯就会在肝脏中积聚,导致脂肪肝。尽管脂肪肝能降低产蛋量,使母鸡的死淘率升高,但对填鸭和鹅脂肪肝的生产是有利的。VLDL合成和分泌的平衡是调节家禽肝脏和肝外组织肥胖的关键因素。 相似文献
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鸡蛋胆固醇的沉积机制 总被引：12，自引：0，他引：12
本文综述了鸡蛋胆固醇的沉积机制。蛋黄胆固醇主要来源于肝脏合成的蛋黄前体—极低密度脂蛋白(VLDL)和卵黄蛋白原(VTG) ,蛋黄胆固醇含量主要取决于VLDL进入卵母细胞的数量。载脂蛋白 -B、载脂蛋白 -Ⅱ(apo -B、apo -II)和卵母细胞原生质膜的受体在VLDL代谢中起着重要作用。通过降低胆固醇合成或替代蛋黄胆固醇来降低蛋黄胆固醇含量作用有限 ,并可能影响卵巢的正常功能和产蛋率等。可望通过调控apo -II和VTG的基因表达来降低蛋黄胆固醇含量。 相似文献
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填饲对朗德鹅与四川白鹅体组成及部分血浆参数的影响 总被引：1，自引：0，他引：1
本试验通过对朗德鹅和四川白鹅单位体重填饲等量饲料,研究了填饲对两品种鹅体重、肝重率、腹脂率、胸肌率、腿肌率等体组成指标以及血浆极低密度脂蛋白(VLDL)、甘油三酯(TAG)、葡萄糖、胰岛素浓度等血浆参数指标的影响。结果表明,填饲后朗德鹅肝增重显著高于四川白鹅,但填饲所导致的四川白鹅皮脂率及腹脂率增长显著高于朗德鹅。填饲后四川白鹅与朗德鹅血浆中VLDL、TAG浓度极显著高于对照组,且四川白鹅血浆中VLDL、TAG浓度显著高于朗德鹅。结果表明,朗德鹅肝脏能更好利用食物中的碳水化合物合成脂类,且合成的脂类优先贮存在肝脏。四川白鹅肝脏合成的脂类贮存在脂肪组织的效率更高。 相似文献
4.
脂肪酸的从头合成发生在肝脏,脂肪组织的生长以及后来的肥胖依赖于以脂蛋白形式转运的血浆甘油三酯。在生长禽VLDL（极低密度脂蛋白）是甘油三酯的主要运输形式,要降低肥胖程度就要通过调节VLDL代谢。现在以腹部脂肪含量和血浆VLDL浓度为标准对脂肪品系和瘦肉品系家禽进行选择．而肝脏的生脂作用和脂肪组织中LPL活性在这两个品系中的差异不显著。当肝脏脂肪合成量大于V．LDL的分泌,甘油三酯就会在肝脏中积聚,导致脂肪肝。尽管脂肪肝能降低产蛋量．使母鸡的死淘率升高,但对填鸭和鹅脂肪肝的生产是有利的。VLDL合成和分泌的平衡是调节家禽肝脏和肝外组织肥胖的关键因素。 相似文献
5.
蛋鸡开产以后,在雌激素作用下,肝脏将由合成普通型极低密度脂蛋白(VLDL)转向大量合成极低密度脂蛋白Y(VLDLy),VLDLy颗粒小,富含甘油三酯、磷脂和胆固醇酯。载脂蛋白VLDL-Ⅱ(apoVLDL-Ⅱ)和载脂蛋白B100(apo-B100)是VLDLy主要的两种载脂蛋白,也受雌激素调控,是VLDLy正确组装所必需的。apoVLDL-Ⅱ是脂蛋白脂酶(LPL)的抑制剂,可以防止VLDLy被降解。这样,VLDLy就可以顺利地通过由卵黄生成素受体(OVR)介导的内吞作用完整地转运进入生长中的卵母细胞。在与受体结合的过程中,OVR的配体结合域LBR1～LBR3起到了关键的作用。可望通过调控apoVLDL-Ⅱ、apo-B100和OVR的基因表达来调控VLDLy的代谢。 相似文献
6.
家禽脂肪酸代谢及其在禽蛋中的沉积和营养调控 总被引：1，自引：0，他引：1
在肝脏中载脂蛋白作用下,内源合成或外源获取的脂肪酸以甘油三酯的形式同胆固醇及其他脂类组装形成极低密度脂蛋白(VLDL)。VLDL经血液循环到达卵巢,穿过卵母细胞外层屏障后,经卵母细胞受体介导的内吞作用进入卵母细胞发生沉积。而机体的营养状况或饲粮中营养成分的改变可通过影响脂肪酸的从头合成或VLDL结构直接或间接影响禽蛋中脂肪酸的最终沉积。本文阐述了家禽体内脂肪酸的来源、转运与沉积过程,并探讨了脂肪酸代谢及其在禽蛋中沉积的营养调控。 相似文献
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犬的高脂血症是指犬血液中的脂质浓度升高,一般指甘油三酯或胆固醇浓度升高.甘油三酯和胆固醇在血液中的运输是由脂蛋白来完成的,犬有4种类型脂蛋白,分别是乳糜微粒、极低密度脂蛋白(very-low density lipoprotein,VLDL)、低密度脂蛋白(low-density lipoprotein,LDL)和高密度脂蛋白(high-density lipoprotein,HDL),HDL可进一步分为HDL1、HDL2和HDL3,其中HDL1是犬所特有的,且不同品种犬的脂蛋白谱具有显著差异.犬血液中的乳糜微粒的主要作用是运输来源于日粮的甘油三酯,VLDL的主要作用是运输肝脏合成的甘油三酯和胆固醇至脂肪组织和横纹肌,LDL的主要作用是运输胆固醇至外周组织,而HDL的主要作用是运输胆固醇至肝脏[1].当犬血液中的甘油三酯浓度升高时,一般为乳糜微粒和/或VLDL升高[2]. 相似文献
9.
影响蛋鸡血浆极低密度脂蛋白（VLDL）含量的环境因素 总被引：7，自引：0，他引：7
生长阶段的蛋鸡血浆极低密度脂蛋白(VLDL)含量很少。开产后血中VLDL浓度与日粮蛋白质水平呈强正相关,并与产蛋率的高低相适应。日粮粗蛋白质为18％时,血中VLDL含量平均在4000～7100mg/100ml,可视为产蛋鸡正常高产水平。环境温度对血中VLDL浓度有影响,但不显著。蛋鸡在17～25℃下血中VLDL含量提高,温度升高(达29～33℃),VLDL含量与蛋白质食入量的相关程度降低。 相似文献
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Effects of β‐hydroxybutyricacid on the synthesis and assembly of very low‐density lipoprotein in bovine hepatocytes in vitro 
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下载免费PDF全文 Q. Deng D. Ma Z. Shi W. Huang X. Du W. Gao X. Zhu L. Lei M. Zhang G. Sun X. Yuan X. Li Z. Wang G. Liu X. Li 《Journal of animal physiology and animal nutrition》2016,100(2):331-336
β‐Hydroxybutyricacid (BHBA) is an important metabolite that involved in the development of ketosis and fatty liver in dairy cows. Dairy cows with fatty liver displayed high blood concentration of BHBA and very low‐density lipoprotein (VLDL) assembly. The effects of BHBA on VLDL synthesis and assembly in hepatocytes of cows were unclear. In this study, bovine hepatocytes were cultured and treated with different concentrations of BHBA. We found that BHBA treatment upregulated the mRNA and protein levels of apolipoprotein B100 (ApoB 100), apolipoprotein E (ApoE) and microsomal triglyceride transfer protein (MTTP) and showed in a firstly increased and then decreased trend. Meanwhile, the mRNA and protein levels of LDLR showed in a reverse trend. Consequently, VLDL content was significantly increased in medium‐dose BHBA treatment group, while decreased in high‐dose group. These results indicate that the effects of BHBA on the VLDL synthesis showed in a dose‐dependent manner that low levels of BHBA increase VLDL synthesis and high levels of BHBA decrease VLDL synthesis. 相似文献
12.
The metabolic origins of equine hyperlipaemia were investigated by analysing the concentration and composition of plasma lipoproteins in 18 ponies with the condition. The mean concentrations of cholesterol, triglyceride and very low density lipoproteins (VLDL) were increased by 4-, 52- and 19-fold, respectively, compared with a control group of 18 healthy ponies. These increases were due to the appearance of a buoyant VLDL fraction (VLDL1) not present in healthy ponies. The mean diameter of VLDL1 particles was 44% greater than control VLDL, and the particles were enriched in triglyceride and free cholesterol and depleted of cholesteryl esters, phospholipid and protein. The apolipoprotein (apo) B-100 content of VLDL1 was reduced and the ratio of apoB-100 to apoB-48 particles was 1:1, compared with 2:1 in control VLDL. The VLDL1 was also enriched in apoE, but had normal complements of apoC-II and apoC-III. The conventional VLDL (called VLDL2), LDL and HDL fractions were moderately enriched with triglyceride, and HDL contained increased amounts of apoE, apoC-II and apoC-III. The activities of lipoprotein lipase and hepatic lipase, the enzymes responsible for the catabolism of VLDL and their remnants, were increased by 2- and 3-fold, respectively, in response to the increased concentrations of their substrates. The composition of VLDL1 suggested that the liver was maximising the secretion of triglyceride by producing larger number of VLDL particles that accommodated a greater mass of triglyceride by having apoB-48 rather than apoB-100 as their structural protein. Plasma free fatty acid (FFA) concentrations were elevated in 17 of the 18 ponies, suggesting that increased FFA flux might be the stimulus for hepatic triglyceride synthesis and VLDL secretion. We conclude that overproduction, rather than defective catabolism, of VLDL was the cause of the hyperlipidaemia and that lipid lowering agents which reduce VLDL synthesis, by decreasing adipose lipolysis and FFA flux, are candidates for the management of hyperlipaemia. 相似文献
13.
Nutritional and management strategies for the prevention of fatty liver in dairy cattle 总被引：2，自引：0，他引：2
Grummer RR 《Veterinary journal (London, England : 1997)》2008,176(1):10-20
Fatty liver occurs in dairy cattle during periods of elevated blood non-esterified fatty acids (NEFAs). Elevated blood NEFAs are associated with hormonal changes at parturition and negative energy balance. Approaches for preventing fatty liver include inhibition of fatty acid mobilization from adipose tissues and altering hepatic metabolism to enhance fatty acid oxidation or export as a constituent of very low-density lipoproteins (VLDL). Nutritional and management strategies to implement these approaches have been examined. Increasing energy density of diet, either by increasing non-fiber carbohydrate or fat, has failed to prevent fatty liver. Two nutritional supplements, ruminally-protected choline and propylene glycol, have proven effective at preventing fatty liver. Choline probably enhances hepatic VLDL secretion. Propylene glycol most likely reduces fatty acid mobilization from adipose tissue. Shortening or eliminating the dry period is a management strategy that reduces the magnitude of negative energy balance after calving and triglyceride accumulation in the liver. 相似文献
14.
产蛋鸡肝脏合成的极低密度脂蛋白对鸡蛋胆固醇和各类营养成分含量都有重要影响，与蛋鸡的胆固醇代谢和脂肪肝综合症之间关系密切。作者综述了产蛋鸡极低密度脂蛋白的组装及影响因素，为深入认识蛋鸡的胆固醇代谢特点和高产蛋鸡的脂肪肝综合症的成因及开发各类功能性鸡蛋有一定的指导作用。 相似文献
15.
Basoglu A Sevinc M Birdane FM Boydak M 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2002,16(6):732-735
The effects of sodium borate (100 mg/kg body weight, p.o., 15 days) from a month before expected calving until a month after calving were evaluated in dairy cows susceptible to fatty liver. Cows received either sodium borate (n = 13) or no treatment (n = 10). All cows had mild fatty livers and increased plasma triglycerides and very low density lipoprotein (VLDL) concentrations at the beginning of the experiment. The control group of cows developed significant fatty liver after calving, and 2 of them had severe fatty liver associated with clinical and biochemical abnormalities. There were no clinicopathological signs related to sodium borate administration. Serum triglycerides and VLDL concentrations before calving decreased significantly at calving and after calving in controls, and they were within the normal range only after calving. There were significant alterations during the experiment in some hematological and chemical variables between groups, within period, but they were within the normal range. Unlike treated cows, serum triglycerides and VLDL concentrations correlated with liver fat content after calving in untreated cows. Our results document that sodium borate decreases the degree of fatty liver in dairy cows during early lactation. 相似文献
16.
Frank N Sojka JE Patterson BW Wood KV Bonham CC Latour MA 《American journal of veterinary research》2003,64(8):1052-1058
OBJECTIVE: To compare kinetics of the metabolism of very-low-density lipoprotein (VLDL) apolipoprotein B (apoB) before and after thyroidectomy in mares. ANIMALS: 5 healthy adult mares. PROCEDURE: Thyroidectomy was performed in euthyroid mares. Kinetics of VLDL apoB metabolism were measured before and after thyroidectomy by use of a bolus IV injection of 5,5,5-2H3 (98%) leucine (5 mg/kg) and subsequent isolation of labeled amino acid from plasma and VLDL. Labeled leucine was quantified by use of gas chromatography-mass spectrometry. Production rate (PR), delay time, and fractional catabolic rate (FCR) were calculated for the 2 forms of equine VLDL, apoB-48 VLDL, and apoB-100 VLDL. Plasma lipid concentrations were measured, and VLDL composition was determined. RESULTS: Physical appearance of horses was not altered by thyroidectomy. Significantly lower mean blood concentrations of thyroid hormones and non-esterified fatty acids were detected following thyroidectomy. Mean percentage of free cholesterol in VLDL was significantly higher after thyroidectomy. Mean plasma VLDL concentration or kinetics of apoB-48 or apoB-100 were not significantly altered by thyroidectomy. Mean +/- SEM PR was significantly lower (8.70 +/- 1.61 mg/kg/d) and mean delay time significantly longer (1.58 +/- 0.12 hours) for apoB-48 VLDL in euthyroid mares, compared with values for thyroidectomized mares (16.15 +/- 2.24 mg/kg/d and 0.93 +/- 0.10 hours, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Hypothyroidism did not significantly alter plasma VLDL concentrations or kinetics of VLDL apoB metabolism. Metabolism of apoB-48 VLDL differed significantly from that of apoB-100 VLDL in euthyroid mares. 相似文献
17.
The hypothesis tested was that the feeding of medium chain triacylglycerols (MCT) to horses would raise the level of plasma triacylglycerols by increasing the availability of glucose as lipogenic substrate, implying that the MCT effect would be greater with glucose in the diet instead of cellulose. A Latin square experiment was carried out with 4 horses and 4 dietary treatments. The experimental periods lasted 21 d. Blood samples were taken 16 h after feeding. The diets consisted of hay and experimental concentrates, differing in fat source (MCT or soybean oil) and carbohydrate source (corn starch plus glucose or cellulose). The dietary variables, MCT or soybean oil, provided on average 27% of total dietary net energy, while glucose plus constarch or cellulose provided 33%. The feeding of MCT versus soybean oil raised the level of plasma triacylglycerols significantly from 196.7 +/- 30.2 to 427.3 +/- 85.7 mmol/l and that of VLDL cholesterol from 0.028 +/- 0.01 to 0.069 +/- 0.01 mmol/ml. As based on analysis of variance, for the four experimental diets there was no significant effect of carbohydrate source and no fat-carbohydrate interaction. Thus, the hypothesis was rejected. When the diets contained soybean oil, cellulose versus starch plus glucose produced significantly greater increase plasma triacylglycerols. This carbohydrate effect was not seen when horses were fed the MCT diets. The experimental concentrates did not differently influence the concentrations of plasma glucose, total serum cholesterol, phospholipids, insulin, free fatty acids and the activity of post-heparin lipoprotein lipase. We suggest that the MCT-induced increase in plasma triacylglycerols is related to an increase in hepatic VLDL secretion, with the extra substrate for increased synthesis of triacylglycerols being the acetyl-CoA derived from the hepatic oxidation of medium chain fatty acids. 相似文献
18.
The purpose of this study was to evaluate changes of very low-density lipoprotein (VLDL) components in hepatic blood (HB) from 5 nonlactating nonpregnant cows fasted from days 0 to 3 and subsequently refed to day 10 and, in addition, to assess those of other lipoproteins. Increased phospholipid concentrations in each lipoprotein after the start of fasting suggested their availability for the surface lipids of lipoproteins. Although the VLDL-triglyceride (TG) concentration in HB from all cows increased on day 1, the value on day 4 became similar to that on day 0. However, the concentration on day 10 was significantly increased. In all cows, the decreased ratio of the VLDL-TG concentration in HB to the non-esterified fatty acids (NEFA) concentration in portal blood (PB) on day 4 appeared to reflect relatively decreased secretion of TG as VLDL by NEFA excessively mobilized to the liver via PB. The markedly increased ratio on day 10 was considered to contribute to the improvement of hepatic lipidosis. 相似文献
19.
OBJECTIVE: To evaluate selected concentrations of blood lipids and lipase activities in euthyroid and hypothyroid horses deprived of feed for 96 hours. ANIMALS: 4 healthy adult mares and 4 thyroidectomized adult mares. PROCEDURE: Horses were deprived of feed for 96 hours. Blood samples were collected at 24-hour intervals and analyzed to determine concentrations of non-esterified fatty acid (NEFA), triglyceride (TG), total cholesterol (TC), and very-low-density lipoprotein (VLDL) as well as composition of VLDL. Plasma lipase activities were measured after feed was withheld for 96 hours and 12 days after resumption of feeding. RESULTS: Time significantly affected plasma NEFA, VLDL, TG, and TC concentrations in both groups of horses. During the 96-hour period, mean plasma concentrations of NEFA and VLDL increased 10-fold in euthyroid horses and increased 5-fold and 9-fold, respectively, in hypothyroid horses. Mean plasma TG concentrations increased 8-fold in both groups, and plasma TC concentrations significantly increased by 33 and 30%, respectively. Composition of VLDL was significantly affected by feed deprivation in euthyroid horses. Activities of lipoprotein lipase and hepatic lipase were significantly higher in feed-deprived horses. Activity of hepatic lipase was significantly lower in hypothyroid horses than in euthyroid horses. CONCLUSIONS AND CLINICAL RELEVANCE: Hypothyroidism did not significantly alter the magnitude of the response of blood lipids to feed deprivation. Thyroid hormones may reduce variability in blood lipid concentrations but do not determine susceptibility to hyperlipemia. Hypothyroidism does not appear to be a factor in the pathogenesis of hyperlipemia in horses. 相似文献