冷应激条件下猪脂肪组织中脂联素及其受体 mRNA水平的表达变化

为了研究冷应激对脂肪代谢的影响,本试验分别在-15~-10 ℃、-10~-5 ℃、-5~0 ℃、15~18 ℃温度条件下采取猪颈部、背部皮下和内脏系膜脂肪组织,通过荧光定量RT-PCR方法检测脂联素及其受体mRNA的表达水平。结果显示,随着冷应激强度的逐渐加大,在颈部、背部皮下、内脏系膜Adiponectin mRNA的表达量逐渐降低,差异显著(P＜0.05);内脏系膜中AdipoR 1和AdipoR 2 mRNA表达量先逐渐升高后恢复正常,且差异极显著(P＜0.01);背部皮下AdipoR 2 mRNA表达量先逐渐降低后恢复正常,差异极显著(P＜0.01),AdipoR 1 mRNA表达量没有明显变化;颈部皮下AdipoR 2 mRNA的表达量先逐渐升高后恢复正常,差异极显著(P＜0.01),AdipoR 1 mRNA的表达量先升高后恢复正常,而后又升高,差异极显著(P＜0.01)。结果表明,脂联素及其受体参与冷应激过程,它们可能与冷应激条件下脂肪组织的重新分布有重要的关系。     

脂联素与其受体的结构及在脂类代谢中的作用机制

脂联素（AdipoQ）是一种主要由脂肪组织分泌的内源性细胞因子,在调节脂类代谢中发挥重要作用。AdipoQ首先与其受体[脂联素受体1(AdipoRl)和脂联素受体2(AdipoR2)]位于膜外的C端结合,再通过AdipoQ受体N端与信号接头蛋白结合,进而激活下游腺苷酸活化蛋白激酶（AMPK）与过氧化物酶体增殖物激活受体α(PPARα)等多条信号通路,促进脂肪酸氧化,抑制脂质合成,从而调节脂类代谢。本文就AdipoQ及其受体的结构、信号接头蛋白和AdipoQ对动物脂质代谢的调节机制进行综述。     

脂联素受体激动剂(AdipoRon)对鸡成骨细胞增殖和凋亡的影响

脂联素受体激动剂(AdipoRon)是人工合成的与脂联素(ADPN)有相似作用的口服活性小分子,研究显示ADPN可调节成骨细胞生长和分化,但AdipoRon是否具有类似的功能目前鲜见报道。本试验主要研究AdipoRon对鸡成骨细胞的影响。从14日龄鸡胚额骨中分离获得成骨细胞,细胞培养第4日,分别添加100,200 mg/L AdipoRon处理成骨细胞,处理72 h后,MTT法检测细胞增殖活性,并进行碱性磷酸酶(ALP)染色。Real-time PCR检测脂联素受体1(AdipoR1)、脂联素受体2(AdipoR2)、成骨细胞成熟标志基因骨钙素(osteocalcin,OC)、Ⅰ型胶原α2链(alpa2 of type I collegen,COL1A2)、细胞凋亡相关基因Caspase-3、Bcl-2及Bax的基因表达量,计算Bcl-2与Bax基因表达量的比值。结果显示,100,200 mg/L AdipoRon处理后的成骨细胞正常形态消失,细胞数量减少,体积变小,细胞核明显固缩,细胞存活率极显著降低(P<0.01)。AdipoRon可增加成骨细胞中AdipoR1、AdipoR2、OC、Bcl-2、Bax和Caspase-3的表达量(P<0.05),并呈剂量依赖性,但对COL1A2和Bcl-2/Bax的表达无显著性影响。结果表明,100,200 mg/L AdipoRon均可促进鸡成骨细胞AdipoR1/2的表达,且能抑制成骨细胞的增殖,促进成骨细胞的成熟及凋亡。     

脂联素受体表达的调节机制

脂联素是一种脂肪细胞分泌的蛋白因子,在人和动物体内通过其受体的介导来发挥多种生理功能,尤以增敏胰岛素、调节糖代谢和脂代谢、保护内皮细胞和对抗炎症等作用重大.本文就脂联素受体1和2的结构和分布、影响它们表达的因素及其机制的进行了综述.     

脂联素在哺乳动物及家禽中的研究进展

脂联素是一种脂肪细胞分泌的蛋白因子,在动物和人体内通过其受体的介导发挥多种生理功能,尤以调节糖代谢和脂代谢、保护血管内皮及对抗炎症等作用重大。本文就哺乳动物和家禽中脂联素及其受体的结构、分布、单核苷酸多态性、表达调节因素及生理功能等方面的研究进展进行综述。     

脂肪细胞因子——脂联素(adiponectin)的研究进展

脂联素是脂肪组织细胞特异性分泌的一种细胞因子,能够调控生物体的能量稳态、糖类和脂类代谢、肥胖、抵抗炎症反应等,具有多种生物学功能,在人类健康方面发挥着重要作用,同样对脂联素的深入研究也对我们在畜牧业生产中如何降低畜禽脂肪沉积,改善肉品质等方面有重要的指导作用。文中就脂联素的来源、结构,对糖和脂肪代谢调控、表达及其受体的研究进展作一综述。     

脂联素及其受体对脂代谢信号转导通路的调控机制

脂联素(Adipo Q)是一种由脂肪组织分泌的细胞因子,在调节畜禽的脂代谢等方面具有重要作用。Adipo Q主要通过与脂联素受体1(Adipo R1)和脂联素受体2(Adipo R2)2种受体结合来调控腺苷酸活化蛋白激酶α(AMPKα)、p38丝裂原激活蛋白激酶(p38MARK)和过氧化物酶体增殖物激活受体α(PPARα)等信号转导通路,参与机体内的脂代谢途径。目前对Adipo Q介导的脂代谢信号转导通路的研究已有了一定进展。本文就Adipo Q及其受体的结构,以及Adipo Q及其受体对脂代谢的调控机制进行了综述。     

皖西白鹅与朗德鹅脂肪基因表达的比较

选择90日龄的皖西白鹅和朗德鹅各20只,取其腹腔脂肪,用半定量逆转录多聚酶链式反应(RT-PCR)的方法,以β-actin为内标,比较分析腹脂中的脂联素(adiponectin,ADP)、脂联素-2型受体(adiponectin receptor 2,ADPR2)、瘦素(leptin, LEP )mRNA的表达,并与腹脂重进行相关性分析,采用ELISA方法测定两种鹅血液中ADP水平.结果表明:皖西白鹅的腹脂重和腹脂率与朗德鹅无显著差异;皖西白鹅腹脂ADP mRNA的表达显著高于朗德鹅(P<0.05),而ADPR2显著低于朗德鹅(P<0.05),LEP mRNA表达在两品种间无显著差异;腹脂重与ADP、AdipoR2、LEP mRNA的表达无显著的相关性;皖西白鹅血液中脂联素含量显著低于朗德鹅(P<0.05).结果提示:①鹅腹脂中ADP及其受体的基因表达存在品种差异;②鹅腹脂分泌的ADP可能不是血液中ADP的主要来源.     

脂联素及其受体在动物下丘脑-垂体-性腺轴中的表达与作用

下丘脑-垂体-性腺(HPG)轴在动物生殖调控中扮演重要角色,研究HPG轴功能的调控因子及机制已成为生殖内分泌学领域的热点。近年来的研究发现,脂肪组织能合成和分泌多种细胞因子,其中脂联素及其受体在调控动物生殖及胚胎生长发育方面起到重要作用,本文就脂联素及其受体在动物HPG轴的表达与作用进行综述。     

脂联素及其受体激动剂在禽脂肪性肝病中的应用展望

脂联素(adiponectin)是一种能参与调控糖和脂质代谢、能量调节、免疫反应以及抵抗炎症、氧化应激和细胞凋亡等多种生理过程的激素。禽脂肪性肝病是由于禽肝脏中脂肪酸合成与酯化、脂肪酸转运、脂肪酸氧化、脂肪分解和利用等代谢途径发生异常, 导致的脂类代谢紊乱、肝细胞脂肪变性和炎症反应。文章介绍了脂联素及其分子结构, 脂联素受体及其参与的信号通路, 并重点阐述了脂联素对肝脏脂质代谢、炎症、氧化应激、肝细胞凋亡与自噬方面的调节作用及机制, 以及脂联素受体激动剂的生理作用。同时, 结合禽脂肪性肝病的发生发展机制, 对脂联素及其受体激动剂的应用前景进行了展望。文章为预防和治疗禽类乃至其他动物的脂肪性肝病提供了新的思路。     

Research Progress on Adiponectin and its Receptors and their Roles in Reproduction

Adiponectin is a special protein which is secreted by adipose tissue and has many kinds of biological functions that play an important role in enhancing fatty acid oxidation,inflammation reaction and anti diabetes ect.Adiponectin mediated by AdipoR1 and AdipoR2 via AMPK,PPAR,p38MAPK signal pathway plays an important role.Adiponectin and its receptors AdipoR1 and AdipoR2 express in many tissues,AdipoR1 is mainly expressed in muscle tissue,AdipoR2 is highly expressed in liver tissue.In addition,adiponectin and its receptors also expressed in the hypothalamus,pituitary,uterus,embryo and other reproductive glands and tissues,which indicate that adiponectin plays an important role in regulating animal reproduction and embryo growth and development.     

Gene expression and hormonal regulation of adiponectin and its receptors in bovine mammary gland and mammary epithelial cells

Although the functions of adiponectin, a differentiated adipocyte‐derived hormone, in regulating glucose and fatty acid metabolism are regulated by two subtypes of adiponectin receptors (AdipoRs; AdipoR1 and AdipoR2), those in ruminants remain unclear. Therefore we examined the messenger RNA (mRNA) expression levels of adiponectin and its receptors in various bovine tissues and mammary glands among different lactation stages, and the effects of lactogenic hormones (insulin, dexamethasone and prolactin) and growth hormone (GH) on mRNA expression of the AdipoRs in cultured bovine mammary epithelial cells (BMEC). AdipoRs mRNAs were widely expressed in various bovine tissues, but adiponectin mRNA expression was significantly higher in adipose tissue than in other tissues. In the mammary gland, although adiponectin mRNA expression was significantly decreased at lactation, AdipoR1 mRNA expression was significantly higher at peak lactation than at the dry‐off stage. In BMEC, lactogenic hormones and GH upregulated AdipoR2 mRNA expression but did not change that of AdipoR1. In conclusion, adiponectin and its receptor mRNA were expressed in various bovine tissues and the adiponectin mRNA level was decreased during lactation. These results suggest that adiponectin and its receptors ware changed in mammary glands by lactation and that AdipoRs mRNA expression was regulated by different pathways in BMEC.     

Adiponectin enhances in vitro development of swine embryos

Recent studies have shown that factors from adipose tissue influence and regulate the reproductive system. Hormones such as leptin and resistin are now known to regulate several reproductive processes. Adiponectin is the most abundant protein secreted by adipose tissue, and its circulating concentration is inversely related to adiposity and body mass index. Little is known about the involvement of adiponectin in reproduction. In the present study, the effect of recombinant adiponectin on the meiotic maturation and early embryo development in vitro was investigated, using porcine oocytes. Adiponectin receptors, AdipoR1 and AdipoR2, were found to be expressed in porcine oocytes and cumulus cells of both small and large follicles. Both AdipoR1 and AdipoR2 were immunolocalized to cumulus-oocyte complexes (COCs), oocytes, and early developing embryos. When included in oocyte maturation medium for 46 h, adiponectin significantly decreased the frequency of meiotic immature oocytes derived from large follicles (3-6 mm) but not from small follicles (<3mm). From studies of oocytes matured in the presence of adiponectin and mitogen-activated protein kinase (MAPK) pathway inhibitors MEK1 (PD98059), MEK1/2 (U0126), and p38MAPK (SB203580) it was concluded that adiponectin enhances oocyte maturation thought the p38MAPK pathway. Finally, a superior rate of embryo development to the blastocyst stage was achieved by embryos cultured in the presence of adiponectin. These results indicate that adiponectin has a positive effect on the meiotic maturation and in vitro embryo development of porcine oocytes and suggests a physiological role for this adipokine in early development in mammals.     

Characterisation of adiponectin and its receptors in the bovine mammary gland and in milk

Adiponectin is an adipocyte-derived hormone, which circulates in the form of homo-multimers. The individual oligomers have a distinct profile of activity, playing crucial roles in several biological processes, including metabolism and inflammation. Adiponectin exerts many of its effects by interacting with the receptors, AdipoR1 and AdipoR2. In the present study, mRNA expression of adiponectin, AdipoR1 and AdipoR2 was evaluated by quantitative PCR in different areas of the mammary gland in healthy lactating cows. The adiponectin isoforms in milk and blood were investigated by Western blotting and 2D-electrophoresis, and the presence of adiponectin protein was determined by immunohistochemistry.Low level expression of adiponectin mRNA was found in all areas of bovine mammary gland tissues examined. AdipoR1 and AdipoR2 mRNAs were also detected in mammary tissues and their expression was particularly prominent in the parenchyma and cistern. Western blotting revealed a heterogeneous electrophoretic pattern, indicating that different adiponectin isoforms exist in milk, compared with blood. In particular, milk shows a low molecular weight isoform of adiponectin, corresponding to the globular domain. Adiponectin in milk is characterised by a more complex 2D electrophoretic pattern, compared with blood, as illustrated by the presence of proteins of different molecular weights and isoelectric points. Adiponectin protein was detected by immunohistochemistry in epithelial cells lining the secretory alveoli, in secretum within the alveolar lumen and in small peripheral nerves. The study findings support a role for adiponectin in regulating metabolism and immunity of the bovine mammary gland and potentially the calf intestine, following ingestion of milk.     

Expression and localization of adiponectin and its receptors in ovarian follicles during different stages of development and the modulatory effect of adiponectin on steroid production in water buffalo

Adiponectin is an adipocyte‐derived hormone regulating energy metabolism, insulin sensitivity and recently found to regulate reproduction. The current study was carried out to investigate gene and protein expression, immunolocalization of adiponectin and its receptors AdipoR1 and AdipoR2 in ovarian follicles of different developmental stages in water buffalo (Bubalus bubalis) and to investigate the effect of adiponectin on steroid production in cultured bubaline granulosa cells. qPCR, western blotting and immunohistochemistry were applied to demonstrate mRNA expression, protein expression and immunolocalization, respectively. The results indicate that adiponectin, AdipoR1 and AdipoR2 were present in granulosa cells (GC) and theca interna (TI) of ovarian follicles and the expression of adiponectin, AdipoR1, AdipoR2 in GC and AdipoR1 and AdipoR2 in TI increased with increase in follicle size (p < .05). Expression of adiponectin was high in small and medium size follicles in TI. The adiponectin and its receptors were immunolocalized in the cytoplasm of GC and TI cells. Further, in the in‐vitro study, GCs were cultured and treated with recombinant adiponectin each at 0, 1 and 10 µg/ml alone or with follicle stimulating hormone (FSH) at 30 ng/ml) or Insulin‐like growth factor I (IGF‐I) at 10 ng/ml for 48 hr after obtaining 75%–80%s confluency. Adiponectin at 10 µg/ml increased IGF‐I‐induced estradiol (E₂) and progesterone (P₄) secretion and FSH‐induced E₂ secretion from GC and also increased the abundance of factors involved in E₂ and P₄ production (cytochrome P45019A1 [CYP19A1] and 3‐beta‐hydroxysteroid dehydrogenase [3β‐HSD]). In conclusion, this study provides novel evidence for the presence of adiponectin and its receptors in ovarian follicles and modulatory role of adiponectin on steroid production in buffalo.     

Adiponectin‐impaired adipocyte differentiation negatively regulates fat deposition in chicken

Adiponectin is a protein hormone secreted exclusively by adipocytes that plays an important role in the modulation of glucose and lipid metabolism. To investigate the effect of adiponectin on lipid metabolism in chicken, rosiglitazone (agonist of adiponectin) and dexamethasone (inhibitor of adiponectin) were used to treat 23‐day‐old broilers in vivo. To verify the functionality of adiponectin on fat deposition, chicken pre‐adipocytes were cultured in the medium containing 10 μg/ml adiponectin. Serum adiponectin and lipids and fat distribution were analysed. Oil Red O staining was used to determine lipid deposition in adipocytes. The expression levels of adiponectin, adiponectin receptors (AdipoR) and lipid metabolism–related genes in different tissues and pre‐adipocytes were measured using real‐time PCR, and the abundance of lipid metabolism–related proteins was measured by Western blot. Rosiglitazone increased serum adiponectin concentration and the expression levels of adiponectin and adiponectin receptor 1 (AdipoR1) in tissues and significantly decreased levels of serum lipids and fat deposition. Rosiglitazone significantly increased the expression levels of adipose triglyceride lipase (ATGL) and AdipoR1 and decreased the expression levels of fatty acid synthase (FAS). Dexamethasone had the converse effects compared with rosiglitazone. Oil red O staining results showed a marked decrease in fat deposition in cells treated with adiponectin. In adipocytes, adiponectin could decrease the expression levels of CCAAT/enhancer‐binding protein α (C/EBPα) and FAS and increased the expression levels of ATGL and AdipoR1. These results indicate that adiponectin has a remarkable effect on impairment of adipocyte differentiation, which contributes to the negative regulation of fat deposition in chicken.     

脂联素与脂联素受体的研究进展

脂联素是脂肪细胞特异分泌的细胞因子，起调节糖类和脂类代谢的作用。作者就脂联素的来源、结构，对糖和脂代谢的调控、表达及其受体的研究进展作一综述。     

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.