瘦素受体表达量在苏钟猪脂肪沉积调控中的作用

瘦素受体（leptin receptor,LEPR）在机体的体质量平衡、造血、生殖、血管生成和免疫过程中发挥着重要作用。为进一步了解LEPR基因在苏钟猪脂肪沉积调控中的作用机制,本研究利用Real-time PCR方法和Western-blot方法分析该基因在12头苏钟猪中5个脂肪易沉积组织（心脏、肝脏、肾脏、背膘和眼肌）RNA和蛋白水平的表达谱信息。结果表明：LEPR的mRNA在这5种组织中均有表达,其在各组织中的mRNA表达丰度表现为：背膘〉眼肌〉心脏〉肝脏〉肾脏,其中在背膘的表达量极显著高于其他几种组织（P〈0.01）;LEPR蛋白在这5种组织中也均有表达,其中在心脏中的表达量最高,显著高于其他组织（P〈0.01）,且在公猪组织的表达量显著高于母猪组织（P〈0.05）;另外,LEPR第18外显子在苏钟猪群中检测到3个高突变率的SNPs。LEPR对苏钟猪的背膘、肌肉、心脏、肾脏、肝脏等组织的脂肪沉积有重要影响,是苏钟猪肉质改良育种中潜在的重要候选基因。     

瘦素及其受体对肌肉组织蛋白质代谢的调节

近年来,体内外试验研究表明,瘦素的短期或长期处理能够调节哺乳动物骨骼肌和肌细胞内蛋白质的代谢,而这主要是由于瘦素可以调节肌细胞内与蛋白质代谢相关的信号通路(如胰岛素相关信号通路和丝裂原活化蛋白激酶信号通路)的活性.因此,本文综述了瘦素及其受体在动物体内肌肉组织蛋白质代谢过程中的调节作用,并分析讨论了这一过程中瘦素的可能...     

鸡胚胎期及新生期肝脏中瘦素受体的表达

本研究通过实时荧光定量PCR的方法检测了14、18日胚龄鸡胚以及2日龄雏鸡肝脏中瘦素受体的表达情况.结果表明:瘦素受体在14、18日胚龄鸡胚以及2日龄雏鸡肝脏中均有表达;随着胚胎及个体的发育,瘦素受体的表达水平降低.     

雌激素受体α,β在雌性山羊肠系膜后神经节的表达

为探究雌激素是否通过交感神经调节雌性生殖系统的生理状态,试验选取雌山羊肠系膜后神经节,采用免疫组织化学SP法,检测雌激素受体α,β在肠系膜后神经节中的表达及分布。结果显示,雌激素受体α,β阳性产物在雌性山羊肠系膜后神经节广泛存在,强阳性产物存在于神经元胞膜和核中,阳性产物存在于整个神经元胞体以及核仁中。在神经节其他组成结构中也出现了阳性产物。表明在雌山羊肠系膜后神经元中存在雌激素受体,说明神经元对雌激素具有反应性;在神经节其他组成结构中出现阳性产物,说明雌激素可以经交感神经通路影响雌性生殖系统的生理机能,为研究雌性生殖系统的免疫神经调节提供了形态学证据。     

牛瘦素受体基因表达及其结合瘦素特性研究

[目的]以秦川牛为研究对象,克隆、原核表达秦川牛瘦素受体(Lepr)基因的蛋白功能区,分析表达蛋白对瘦素结合特性,为研究瘦素受体与瘦素结合的调节机制提供理论基础.[方法]本研究通过RT-PCR法从秦川牛肉mRNA扩增获得Lepr IG基因的cDNA序列,克隆至pMD18-T载体获得重组质粒,并进行序列测定.将测序正确的...     

瘦素（leptin）与雌性哺乳动物的繁殖活动关系的研究进展

随着对瘦素研究的不断深入,发现其不仅参与食物摄入和能量平衡,而且对雌性哺乳动物的繁殖活动也发挥着重要的调节作用。本文主要就瘦素对母畜初情期的启动、发情、早期胚胎发育、受精卵的着床、妊娠的维持、胎儿的生长发育、乳腺发育和乳汁分泌等繁殖活动的影响进行综述。     

褪黑素受体在牦牛子宫中的表达分析

为探究褪黑素受体（MTNR）在牦牛子宫中的定位及表达与妊娠的关系,本研究利用免疫组织化学技术（S-P法）分别检测未妊娠、妊娠25~45 d、妊娠50~85 d、妊娠90~110 d牦牛子宫中MTNR的表达情况。结果表明：MTNR免疫阳性产物在牦牛子宫腺上皮细胞、腔上皮细胞、基质细胞、血管平滑肌细胞、血管内皮细胞、肌层平滑肌细胞均有表达;不同妊娠阶段牦牛子宫中的基质细胞和肌层平滑肌细胞中均有MTNR的表达,但其差异性不显著（P〉0.05）;血管内皮细胞和血管平滑肌细胞中的MTNR表达强度随着妊娠阶段时间的增加且差异性显著（P〈0.05）;腺上皮细胞中的MTNR在妊娠后期表达强度增加且差异极显著（P〈0.01）;腔上皮细胞的MTNR在妊娠后期表达强度降低（P〈0.01）。     

猕猴脾脏中雌激素受体的表达及其性别差异

选取健康成年雌雄猕猴各3只,采用免疫组织化学SP法研究了雌激素受体(ER)在脾脏中的分布,观察猕猴脾脏中ER的表达及性别差异.结果显示,ER免疫阳性反应物主要分布于脾脏红髓区,脾小结相对较少,而动脉周围淋巴鞘、血管内皮、脾小粱等组织结构内仅有少量分布.ER阳性产物主要定位于细胞核中.部分存在于胞浆和胞膜上.雌性猕猴脾脏中的阳性细胞数量显著高于雄性,表达强度也较雄性强.这表明,ER参与雌激素对脾脏的免疫功能调控.ER阳性产物分布特点表明雌激素发挥作用主要是通过经典基因组机制,同时也通过非基因组机制途径.而ER表达的明显性别差异提示体内雌激素水平可能对脾脏中B淋巴细胞的功能有正调节作用.     

雌激素受体α在雌性大鼠脑中的表达

本试验利用免疫组织化学SP法,研究了雌激素受体α在大鼠脑中的表达.结果表明,ER_α免疫反应产物主要定位于神经元细胞核,部分区域出现阳性神经元和阳性突起,在海马CA1、CA2辐射层、齿状回、下托的分子层等出现阳性星形胶质细胞;ER_α在脑中表达广泛,免疫反应产物在端脑的隔外侧核、海马锥体细胞层、大脑皮质等,间脑的缰内侧核、下丘脑室旁核、弓状核、视上核等,中脑的动眼神经核,脑桥的脑桥核外侧部等为高密度;在端脑的尾壳核、杏仁中央核、海马CA4区,间脑的下丘脑室周核、缰外侧核等,中脑的黑质致密带,脑桥的脑桥被盖核等为较高密度;在问脑的视前室周核、丘脑后核、中脑的红核、脑桥的脑桥被盖网状核等为中等密度;在端脑的苍白球,间脑的无名质,无免疫反应产物出现.结果显示,雌激素在调节脑的认知和生殖内分泌过程中,ER_α可能起主要作用;雌激素可通过ER_α调节星形胶质细胞功能.     

猪Toll样受体5基因cDNA克隆、蛋白质序列分析及其意义

为了解猪Toll样受体5(TLR5)蛋白的结构特征和进化关系,本研究从肠系膜淋巴结组织总RNA中克隆出猪Toll样受体5基因的cDNA序列。序列全长2641bp,其中2571bp的开放阅读框编码856个氨基酸残基的猪TLR5,含17.4%的亮氨酸,并有一段19个氨基酸的信号肽序列;同源性分析结果显示,TLR5在进化过程中具有高度保守性,与人、牛、山羊、绵羊、小鼠和大鼠的氨基酸序列同源性分别为77.5%、79.6%、78.3%、81.0%、69.2%和68.9%。蛋白分子结构预测结果表明,该分子由胞外区(642个氨基酸)、跨膜区(23个氨基酸)和胞内区(191个氨基酸)组成,胞外区具有LRR结构域,胞内区具有TIR结构域,表现出典型的TLR家族结构特征。表明猪TLR5分子具有病原分子模式识别和信号传导的作用,这为其结构与功能的进一步研究奠定了基础。     

Plasma leptin levels in pigs with different leptin and leptin receptor genotypes

A C3469T mutation at exon 3 of the pig leptin (Lep) gene has been genotyped in diverse pig breeds yielding controversial results with regard to its association with growth, fatness and carcass traits. A similar situation has been reported for a HpaII restriction fragment length polymorphism (RFLP) in the pig leptin receptor (Lepr) gene, where associations were found depending on the statistical model employed. The main objective of our work was to investigate if leptin plasma concentrations differ in pigs with different C3469T and Lepr HpaII RFLP genotypes. With this aim, we have measured plasma leptin levels at 160 days in 68 Landrace pigs with different Lep C3469T and Lepr HpaII RFLP genotypes. Neither Lep (TT: 11.68 ng/ml, TC: 10.71 ng/ml) nor Lepr (AA: 12.6 ng/ml, AB: 10.93 ng/ml, BB: 11.74 ng/ml) genotypes influenced significantly plasma Lep concentration. Moreover, we did not find any association between Lep and Lepr genotypes and phenotypic variation at growth and fatness traits in a commercial population of 320 Landrace pigs.     

Localization of leptin and leptin receptor in the bovine adenohypophysis

The present study was carried out to detail the cellular localization of leptin (Lep) and the leptin receptor (LepR) in the bovine adenohypophysis. Lep immunoreactivity (Lep-ir) was found in about 30% of adenohypophysial cells in the gland. Immunochemistry of Lep and specific hormones using serial sections revealed that Lep-ir was present in 60.4% of somatotrophs, 15.9% of gonadotrophs, 6.5% of mammotrophs, 6.5% of thyrotrophs and 2.4% of corticotrophs. Both the common short isoform (OBRa) and the long isoform (OBRb) of LepR mRNA were expressed in the bovine adenohypophysis. LepR immunoreactivity (LepR-ir) was found in only 2.8% of the adenohypophysial cells and over 50% of LepR-ir cells were gonadotrophs, in which most of the cells were distributed in the zona tuberalis. The findings on Lep and LepR in the adenohypophysial cells indicate that Lep may regulate gonadotroph function through autocrine/paracrine pathway in the bovine adenohypophysis.     

Investigation of the leptin levels in the blood serum of Cyprinus carpio (Linnaeus, 1758) and Capoeta trutta (Heckel, 1843)

Leptin is a peptide hormone secreted by adipose tissues in the various teleost fish and vertebrates. Leptin has been suggested to have an important role in a range physiological function, including regulation of food intake, reproduction, immune function, energy expenditure, lipid and carbohydrate metabolism. In this study, leptin levels in the blood serum of Cyprinus carpio and Capoeta trutta were determined. Then the results were compared between two species and between sexes of each species. In addition, leptin levels were also compared with the body weight and length of both C. carpio and C. trutta. Leptin level was analysed using available enzyme‐linked immunoassay (ELISA) kit (Rat leptin ELISA kit, catalog no: SK00050‐08). Leptin levels showed no significant difference (p > 0.05) that in relation to between two species and between sexes of each species. It has been shown that not significantly correlated when examined correlations between the leptin level in blood serum and body weight (r = 0.192, p = 0.380) or length (r = 0.102, p = 0.644) of C. carpio. Similarly, the correlations between leptin level in blood serum and body weight (r = 0.021, p = 0.959) or length (r = 0.123, p = 0.595) of C. trutta were also not significant.     

Presence and distribution of leptin and its receptor in the gut of adult zebrafish in response to feeding and fasting

Leptin is an anorectic hormone secreted mainly by peripheral adipocytes but also by other central and peripheral tissues. It acts by means of a receptor called OB‐R, influencing not only appetite and body mass but being also involved in many fields like endocrinology, metabolism and reproduction. Immunohistochemistry and qRT‐PCR techniques were, respectively, used to demonstrate the presence of leptin and its receptor in the gut of adult zebrafish and to evaluate the leptin gene expression response to feeding and fasting. Immunoreactivity for the antibodies utilized was demonstrated in feeding but not in fasting fish, and the gene expression analysis corroborates the data obtained by immunohistochemistry. Therefore, all the obtained results support the hypothesis of the role of this hormone in food regulation in zebrafish.     

Effects of porcine leptin receptor gene polymorphisms on backfat thickness,fat area ratios by image analysis,and serum leptin concentrations in a Duroc purebred population

The leptin receptor (LEPR) gene is considered a candidate gene for fatness traits. It is located on SSC 6 in a region in which quantitative trait loci (QTLs) for backfat thickness (BF), fat area ratios, and serum leptin concentration (LEPC) have previously been detected in a Duroc purebred population. The objectives of the present study were to identify porcine LEPR polymorphisms and examine the effects of LEPR polymorphisms on fatness traits in this same population. The Duroc pigs (226 to 953 pigs) were evaluated for BF, fat area ratios using image analysis, and LEPC. A total of seven single nucleotide polymorphisms (SNPs) in the full‐length LEPR coding region were identified in pigs from the base population. Four non‐synonymous SNPs of the LEPR gene and 15 microsatellite markers on SSC 6 were then genotyped in all pigs. During candidate gene analysis, we detected significant effects of the non‐synonymous SNP c.2002C>T in exon 14 on all traits. In fine mapping analysis, significant QTLs for BF, fat area ratios, and LEPC were detected near the LEPR gene in the same region. These results indicated that the c.2002C>T SNP of LEPR has a strong effect on BF, fat area ratios and LEPC.     

猪颈前神经节脊髓颈部和胃内Leptin长形受体mRNA的分布定位

用原位杂交法研究了10头长白猪(n=5)和梅山猪(n=5)颈前神经节、脊髓颈部和胃内Ob—Rb mRNA的分布定位。实验结果表明，Ob—Rb mRNA标记神经元位于长白猪和梅山猪颈前神经节、脊髓颈部和胃内。在颈前神经节，Ob—Rb mRNA标记神经元散在分布，胞体呈圆形或卵圆形。在脊髓颈部，Ob—Rb mRNA标记神经元分布于背侧角和腹侧角，以背侧角分布密集。在胃内，Ob—Rb mRNA标记细胞分布于黏膜层和黏膜下层。长白猪和梅山猪上述结构内Ob—Rb mRNA的分布定位无明显差异。     

Plasma leptin, feed intake and body fat accumulation in fattening castrated male and female lambs

The main objective of this study was to investigate the relationships between changes in plasma leptin concentration and feed intake or bodyweight in female and castrated male lambs with fattening. Four female and four castrated male lambs were used and were fed roughage and concentrate supplemented with beef tallow ad libitum for 28 weeks. Although the feed intake and bodyweight increased with fattening in both the castrated male and female lambs, they decreased at 24–28 weeks in the female lambs. At the end of fattening, the crude fat content in the muscle (loin) of the female lambs was significantly higher than in the castrated male lambs (P < 0.05), while the crude protein content in the loin and fillet meat was higher in the castrated male than in the female lambs (P < 0.05). The plasma leptin concentration showed high values at a later stage of fattening (P < 0.05). In the female lambs the plasma insulin concentration increased at a later stage of fattening (P < 0.05) and was positively correlated (P < 0.0001, r = 0.78) with plasma leptin. Plasma metabolites (glucose, nonesterified fatty acid, total cholesterol and triglyceride) concentrations were also changed with fattening. Plasma total cholesterol was positively related to plasma leptin, more closely in the female than in the castrated male lambs (in females, r = 0.63, P < 0.001; in males, r = 0.38, P < 0.01). The accumulation of body fat was probably accelerated by the consumption of a lot of concentrate feed supplemented with treated beef tallow and by the stimulation of insulin with fattening. Consequently, the plasma leptin concentration increased, especially toward the end of the fattening period. The decrease in feed intake and bodyweight after the 24th week of fattening was possibly caused by an increase in leptin that is involved in the homeostatic regulation of body energy by regulating appetite.