营养水平对DLY杂交猪肉质性状及H-FABP基因表达的影响

将24头起始重为(64.24±2.66)kg的健康DLY杂交猪随机分为2个处理,分别饲喂高、低营养水平的日粮,研究高、低营养水平对育肥猪肉质性状及H-FABP基因表达的影响。结果表明:与低营养水平相比,高营养水平提高了日增重(P=0.273)和饲料报酬(P=0.001);降低营养水平可提高H-FABP基因表达量(P=0.288)和IMF含量(P=0.09),增加肉的嫩度(P=0.026);降低营养水平,还提高了肌肉组织中苹果酸脱氢酶和脂蛋白脂酶的活性(P>0.05)。因此,营养水平可以影响肌肉组织脂肪代谢和H-FABP基因的表达。     

Fasting regulates the expression of adiponectin receptors in young growing pigs

Adiponectin is an adipocyte-derived hormone that can improve insulin sensitivity. Its functions in regulating glucose utilization and fatty acid metabolism in mammals are mediated by 2 subtypes of adiponectin receptors (AdipoR1 and AdipoR2). This study was conducted to determine the effect of fasting on the expression of adiponectin and its receptors. The expression of adiponectin was not affected in s.c. adipose tissue, but adiponectin expression increased in visceral adipose tissue after fasting. In contrast, expression of both AdipoR mRNA was increased in the liver and s.c. adipose tissue of 24-h-fasted pigs compared with fed pigs, but the mRNA in muscle and visceral adipose tissue was not affected by fasting. A third putative adiponectin receptor, T-cadherin, was cloned and the mRNA expression was determined. T-Cadherin has been recognized to act as a vascular adiponectin receptor in vascular endothelial and smooth muscle cells. Our data showed that the expression of T-cadherin was decreased in the muscle of fasted pigs, suggesting that the expression of T-cadherin can be regulated by feeding status. In summary, in young pigs, adiponectin mRNA was up-regulated by fasting in visceral, but not s.c., adipose tissue, whereas AdipoR1 and AdipoR2 mRNA were increased in s.c., but not visceral, adipose tissue. The adiponectin receptor, T-cadherin, was expressed in s.c. and visceral adipose tissue and in muscle, but only muscle mRNA expression was decreased by fasting.     

The effect of porcine somatotropin supplementation in pigs on the lipid profile of subcutaneous and intermuscular adipose tissue and longissimus muscle.

The effect of porcine somatotropin (pST) on the lipid profiles of adipose tissue and muscle was investigated. Sixteen crossbred barrows were injected daily with either 3 mg of pST or a placebo. After slaughter, total lipid and fatty acid composition of raw subcutaneous (SC) adipose and intermuscular (IM) adipose tissue and longissimus muscle were determined. The SC adipose tissue from pST-treated pigs had a 7.5% decrease in total lipid content; specific fatty acids 16:0, 18:0, and 18:1(n-9)c decreased most. The IM fat from pST-treated pigs had lower levels of 16:0 and 20:0. There was no effect of pST treatment on the lipid profile of the longissimus muscle. The data suggest that pST treatment produces small but significant changes in the saturated fatty acid content of adipose tissue in pigs.     

巨型玫瑰冠鸡H-FABP、A-FABP基因表达的发育性变化及其肌内脂肪含量研究

为探讨心脏型脂肪酸结合蛋白（heart-type fatty acid-binding protein，H-FABP）和脂肪型脂肪酸结合蛋白（adipocyte fatty acid-binding protein，A-FABP）基因与巨型玫瑰冠鸡生长发育及肌内脂肪含量（IMF）的关系，研究H-FABP、A-FABP基因对巨型玫瑰冠鸡IMF含量和腹脂沉积的作用机制，本试验采集了巨型玫瑰冠鸡与良凤花鸡在不同周龄（2、4、6、8、10、12周龄）的腹脂、心肌、胸肌、腿肌组织样品共480份，采用实时荧光定量PCR对巨型玫瑰冠鸡与良凤花鸡不同生长阶段组织中H-FABP、A-FABP基因mRNA表达量进行了检测，并采用索氏浸提法测定了两种鸡12周龄的胸肌与腿肌的IMF含量。结果表明，巨型玫瑰冠鸡与良凤花鸡的H-FABP、A-FABP基因mRNA在腹脂、心肌、胸肌和腿肌组织中均有不同程度的表达，且两种鸡H-FABP基因mRNA在心肌组织中高度表达，在脂肪组织中表达量较低，在胸肌、腿肌组织中中度表达，而A-FABP基因相反，推测H-FABP基因主要在肌肉组织中表达，而A-FABP基因主要在脂肪组织中表达。良凤花鸡生长速度高于巨型玫瑰冠鸡；巨型玫瑰冠鸡的腹脂率均低于同性别的良凤花鸡，但胸肌、腿肌的IMF均高于同性别的良凤花鸡，表明巨型玫瑰冠鸡的肉品质优于良凤花鸡。本试验结果为巨型玫瑰冠鸡H-FABP、A-FABP基因分子选育奠定了基础。     

Acute changes in blood flow in pigs infused with beta-adrenergic agonists

Previous results indicate that clenbuterol decreases carcass adipose tissue accretion when administered to pigs but does not appear to stimulate the adipose tissue beta-adrenergic receptor. Clenbuterol increases plasma free fatty acid concentration when acutely infused in vivo, suggesting an indirect affect. One possible indirect effect is that clenbuterol could change blood flow to adipose tissue. Blood flow was measured with radiolabeled microspheres in tissues from pigs before and after infusion of a beta-adrenergic agonist for 30 min. High probability levels (up to P less than .2) were used to indicate trends due to extreme variability. Infusion of isoproterenol increased heart rate, plasma free fatty acid concentration and blood flow at many adipose tissue sites and at a few skeletal muscle sites. Infusion of isoproterenol decreased blood pressure. Infusion of clenbuterol increased heart rate and tended to increase blood flow to several skin and adipose tissue sites slightly. The results suggest that increased adipose tissue blood flow may contribute to the accelerated release of free fatty acids when clenbuterol is infused acutely in vivo.     

Beta 3-adrenergic agonist up-regulates uncoupling proteins 2 and 3 in skeletal muscle of the mouse

Chronic stimulation of the beta3-adrenergic receptor (AR) in obese animals resulted in a reduced adiposity associated with an increased expression of thermogenic uncoupling protein (UCP)1 in adipose tissues. In this study, the mRNA expression of newly cloned UCP isoforms (UCP2 and UCP3) were examined in obese yellow KK and C57BL control mice. UCP2 mRNA was found in all tissues examined, with higher levels in adipose tissues and skeletal muscle of the obese mice. UCP3 mRNA was expressed in skeletal muscle, heart and brown adipose tissue similarly in the two mouse strains. Daily injection of a selective beta3-adrenergic agonist, CL316,243 (0.1 mg/kg), for 10 days resulted in a marked reduction of white fat pad weight and 1.8-4.8-fold increase in the mRNA levels of UCP2 and UCP3 in skeletal muscle of obese mice. No noticeable change in the UCP2 and 3 mRNA levels was found in brown and white adipose tissues. It was also found that CL316,243 injection produced a marked and sustained elevation of the plasma free fatty acid level. These results, together with our previous findings of the fatty acid-induced UCP expression in a myocyte cell line in vitro, suggest that the beta3-AR agonist-induced UCP expression in skeletal muscle may be mediated through the elevated plasma free fatty acids. It was also suggested that anti-obesity effect of beta3-AR agonists is attributable to increased thermogenesis not only by UCP1 but also by UCP2 and UCP3.     

猪CRTC3基因表达的品种差异及forskolin对其表达的影响

本试验旨在探究糖脂代谢通路关键基因CRTC3在不同品种猪肌肉和脂肪组织中的表达情况,并通过forskolin处理猪皮下脂肪前体细胞,研究forskolin对脂肪前体细胞分化聚酯和CRTC3基因表达的影响,阐明猪CRTC3基因表达与脂肪沉积的关系。试验选取杜长大猪和莱芜猪各5头,检测肌肉、脂肪组织中CRTC3的mRNA和蛋白表达水平以及脂肪代谢相关基因的mRNA表达水平;选取2头3日龄的杜长大仔猪,分离猪皮下脂肪前体细胞,待完全融合后用MDI诱导培养基诱导4 d,然后用分化培养基继续诱导4 d,完成诱导分化。Forskolin组在诱导分化的第1天即加入forskolin,使其终浓度为10μmol/L,对照组则加入同浓度的二甲基亚砜(DMSO)进行诱导分化。结果表明:在莱芜猪的背最长肌和腰大肌中,CRTC3的蛋白表达水平高于杜长大猪;在莱芜猪的皮下和内脏脂肪组织中,CRTC3及脂肪沉积相关基因过氧化物酶体增殖剂激活受体γ(PPARγ)、脂肪酸结合蛋白4(FABP4)、CCAAT/增强子结合蛋白α(C/EBPα)、围脂滴蛋白(PLIN)和瘦素(LEP)的mRNA表达水平显著或极显著高于杜长大猪(P<0.05或P<0.01),而脂肪棕色化相关基因NF-E2相关因子1(NRF1)、过氧化物酶体增殖物激活受体-γ共激活因子-1α(PGC⁃1α)、PRDM16、解偶联蛋白2(UCP2)、解偶联蛋白3(UCP3)的mRNA表达水平则显著或极显著低于杜长大猪(P<0.05或P<0.01)。进一步的研究发现,猪皮下脂肪前体细胞分化后CRTC3和脂肪沉积相关基因的mRNA表达水平极显著提高(P<0.01),脂肪棕色化相关基因的mRNA表达水平也均极显著升高(P<0.01)。10μmol/L forsko⁃lin处理能抑制猪皮下脂肪前体细胞分化,极显著升高环磷腺苷效应元件结合蛋白(CREB)和脂肪棕色化相关基因的mRNA表达水平(P<0.01),促进CRTC3的进核,极显著降低CRTC3和脂肪沉积相关基因的mRNA表达水平(P<0.01)。上述研究结果表明,CRTC3基因与猪脂肪沉积密切相关,forskolin处理可以调控猪CRTC3及脂质代谢相关基因表达,调控猪皮下脂肪前体细胞分化聚酯。     

Effects of in vitro ronnel on metabolic activity in subcutaneous adipose tissue and skeletal muscle from steers

Ronnel [0,0-dimethyl 0-(2,4,5-trichlorophenyl) phosphorothioate] is an organophosphate pesticide with growth-promoting properties. Experiments were conducted to determine effects of ronnel on oxidation of and fatty acid synthesis from acetate and glucose as indices of metabolic activity in subcutaneous adipose tissue and skeletal muscle from 6-, 12- and 18-mo-old steers. Ronnel depressed metabolic activity in adipose tissue from 6- and 12-mo-old steers without concomitantly decreasing metabolic activity in skeletal muscle. Production of CO2 and fatty acids from acetate and glucose in tissues from 18-mo-old steers was influenced less by ronnel than in tissues from younger steers. Interactions of ronnel with thyroxine or growth hormone on acetate oxidation and conversion to fatty acids in adipose tissue also were investigated. Thyroxine increased acetate oxidation and decreased fatty acid synthesis. Ronnel interfered with the metabolic effects of thyroxine. Growth hormone, with or without ronnel, did not affect metabolic activity of adipose tissue. Ronnel seemingly alters the partitioning of acetate and glucose between major metabolic processes in adipose tissue and skeletal muscle.     

Porcine somatotropin decreases acetyl-CoA carboxylase gene expression in porcine adipose tissue

Crossbred barrows were treated daily with porcine somatotropin (pST; 4 mg/d) from 79 to 127 kg BW to determine whether pST regulates the activity and gene expression of adipose tissue acetyl-CoA carboxylase (ACC), the rate limiting enzyme in de novo fatty acid synthesis. Administration of pST reduced ACC enzyme activity, protein content, and mRNA abundance in adipose tissue by 40 to 50%. When comparisons were made among all pigs, ACC enzyme activity and mRNA abundance were closely associated (r² = .94). In summary, our results indicate that pST decreases ACC enzyme activity and that this is associated with a significant reduction in ACC mRNA abundance. We speculate that decreased ACC enzyme activity results from a reduction in ACC protein and that this occurs because pST reduces the abundance of mRNA available for translation.     

Dietary conjugated linoleic acid alters fatty acid composition of pig skeletal muscle and fat

The dietary dose responsiveness of conjugated linoleic acid (CLA) addition relative to the fatty acid profile of edible lean tissue was examined in grower pigs treated with or without porcine somatotropin (pST). Gilts and barrows were fed CLA at 0, 0.25, 0.5, 1.0, or 2.0% of diet by weight from 20 to 55 kg BW. Additional pigs were administered (pST) at 0 or 100 microg x kg BW x d(-1) and fed either 0.5 or 2.0% CLA. Animals were fed diets containing 18% CP, 1.2% lysine, and 3.5 Mcal of DE/kg at 110% of ad libitum intake. The fatty acid profile in latissimus dorsi and dorsal s.c. adipose tissue samples was determined by gas chromatography. Dietary CLA replacement of corn oil increased the percentage of total fatty acids as stearic acid, whereas the percentages as oleic and linolenic acids were reduced in lattisimus muscle. Treatment with CLA + pST increased the percentages of linoleic and arachidonic acids while reducing the percentages of palmitic and oleic acids in lattisimus muscle. Dietary CLA increased the percentages of palmitic and stearic acids in s.c. adipose tissue while reducing the percentages of oleic, linoleic, linolenic, and arachidonic acids. The percentage of palmitic acid was reduced in s.c. adipose tissue, whereas linoleic acid was increased with CLA + pST. No synergistic effect was detected between CLA and pST for reducing carcass lipid content in grower pigs. However, pST increased the percentage of polyunsaturated fatty acids in lattisimus muscle and s.c. adipose tissue while reducing the percentages of saturated fatty acids in swine fed CLA.     

Analysis of myostatin and its related factors in various porcine tissues

Myostatin is expressed in skeletal muscle tissue where it functions to suppress myoblast proliferation and myofiber hypertrophy. Recently, myostatin was detected in the tendon, mammary gland, and adipose tissue of mice. We sought to determine whether myostatin is expressed in the liver, spleen, lung, and kidney of pigs. Real-time PCR and Western blots demonstrated that myostatin, follistatin, decorin, and activin receptor IIB (ActRIIB) mRNA and proteins were expressed in skeletal muscle, heart muscle, and adipose tissue, and also in liver, spleen, lung, kidney, and cultured fibroblasts. The relative abundance of myostatin was closely related to follistatin and decorin in porcine tissues. Immunohistochemical analysis further demonstrated the presence of myostatin, follistatin, and decorin in the skeletal muscle, adipose tissue, heart muscle, liver, spleen, lung, and kidney of pigs. These results suggest that myostatin could be associated with certain functions of the internal organs, such as energy metabolism or fibrosis. We conclude that myostatin is a factor broadly expressed in the internal organs and muscle tissues of pigs.     

兰州大尾羊H-FABP基因荧光定量PCR检测方法的研究

通过对兰州大尾羊尾部、大网膜、肝脏、肾周脂肪组织中的总RNA提取,反转录获得总cDNA样品,结合PCR技术,建立了SYBR荧光定量PCR法检测兰州大尾羊心脏型脂肪酸结合蛋白（H-FABP）基因mRNA在不同组织中相对表达量的试验方法,并进行批内、批间重复性检验。结果表明,H-FABP和18S基因标准曲线回归方程分别为CtH-FABP =-3.24375x+38.34230和Ct18S=-3.33137x+33.4573,相关系数（r2）分别为0.9964和0.9992,扩增效率分别为103%和99%;批内、批间重复性测定的变异系数分别为小于1.8%和10%;说明该方法灵敏度高、特异性强、准确可靠、重复性好,是实时荧光定量PCR检测兰州大尾羊心脏型脂肪酸结合蛋白基因mRNA表达量的有效方法。     

Regulation of hepatic peroxisome proliferator‐activated receptor α expression but not adiponectin by dietary protein in finishing pigs

Soy protein regulates adiponectin and peroxisome proliferator‐activated receptor α (PPARα) in some species, but the effect of dietary soy protein on adiponectin and PPARα in the pig has not been studied. Therefore, the objective of this study was to determine whether soya bean meal reduction or replacement influences serum adiponectin, adiponectin mRNA, serum metabolites and the expression of PPARα and other genes involved in lipid deposition. Thirty‐three pigs (11 pigs per treatment) were subjected to one of three dietary treatments: (i) reduced crude protein (CP) diet containing soya bean meal (RCP‐Soy), (ii) high CP diet containing soya bean meal (HCP‐Soy) or (iii) high CP diet with corn gluten meal replacing soya bean meal (HCP‐CGM) for 35 days. Dietary treatment had no effect on overall growth performance, feed intake or measures of body composition. There was no effect of dietary treatment on serum adiponectin or leptin. Dietary treatment did not affect the abundance of the mRNAs for adiponectin, PPARα, PPARγ2, lipoprotein lipase or fatty acid synthase in adipose tissue. The mRNA expression of PPARα, PPARγ2, lipoprotein lipase or fatty acid synthetase in loin muscle was not affected by dietary treatment. In liver tissue, the relative abundance of PPARα mRNA was greater (p < 0.05) in pigs fed the HCP‐Soy diets when compared to pigs fed RCP‐Soy or HCP‐CGM diets. Hepatic mRNA expression of acyl‐CoA oxidase or fatty acid synthase was not affected by dietary treatment. Western blot analysis indicated that hepatic PPARα protein levels were decreased (p < 0.05) in pigs fed the RCP‐Soy diets when compared to pigs fed the HCP‐Soy diets. These data suggest that increasing the soy protein content of swine diets increases hepatic expression of PPARα without associated changes in body composition.