瘦素的生物学功能及其应用前景

瘦素可以降低脂肪含量、改变体组成、维持能量平衡，提高机体抗应激能力和免疫机能，促进动物新陈代谢。从而提高畜禽生产性能和经济效益。本文从调控机制、抗性、能量平衡及其在动物体内的作用等方面综述了瘦素生物学功能的研究进展，并从神经内分泌和分子生物学水平探讨瘦素的作用机理，指出其在畜牧业上的应用前景；     

代谢信号对能量影响猪卵泡发育的作用

动物体内的许多激素和因子通过内分泌活动把能量摄入和繁殖系统联系起来。卵巢上卵泡的发育是雌性动物繁殖系统中的重要因素,是繁殖性能的基础。猪的生产是人们生活中主要的肉类来源之一,能量对猪卵泡发育的影响日益受到关注。日粮能量水平的变化会影响到体内循环与营养代谢相关的激素和因子,而这些激素和因子的变化可能会作为代谢信号对卵泡的发育产生影响。这些代谢信号包括胰岛素、瘦素和胰岛素样生长因子-Ⅰ等。研究表明,代谢信号对下丘脑、垂体和卵巢均有影响。在胰岛素、瘦素和胰岛素样生长因子-Ⅰ等代谢信号的介导下,日粮能量营养因素通过改变下丘脑-垂体-卵巢轴的活性,对雌性动物的卵泡发育产生影响。     

动物肥胖基因（ob）的研究进展

肥胖基因（ob）调节动物生长和维持能量平衡的生物学功能都是通过其产物——瘦素蛋白（Leptin）来实现的.因此,控制Leptin在动物体内的表达水平可有效降低脂肪含量,提高瘦肉率,从而为畜牧产业带来可观的经济效益.就ob基因的研究进展进行了系统性的综述.     

瘦素减少体脂沉积调节生殖的作用机理

1 瘦素的生理特性 瘦素主要由白色脂肪产生，棕色脂肪、骨髂肌、胃黏膜、胎盘及胎儿的心脏、骨软骨组织也可分泌．由肾脏排出。瘦素除了刺激下丘脑饱食中枢调控动物的摄食行为和脂肪代谢外，还能通过神经一体液机制间接或直接作用于体内大多数器官和组织．发挥复杂的生理调控作用。     

瘦素对哺乳动物初情启动的影响及其可能机制

脂肪细胞分泌的瘦素作为新陈代谢的信号因子在动物繁殖过程中扮演着重要的角色。由能量负平衡造成的血液中瘦素浓度降低或因缺少功能性的瘦素及其受体时会导致动物初情期启动发生紊乱。近年来研究表明,瘦素能调节下丘脑Kiss-1神经元Kisspeptin蛋白分泌来影响下丘脑-垂体-性腺轴功能,进而引起动物一系列生理活动的变化。因此,本文结合近年来的新发现总结了瘦素对哺乳动物初情启动的影响及其可能的作用机制。     

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...     

瘦素对动物生殖调控的研究进展

瘦素是由白色脂肪细胞分泌的一种蛋白类激素,对动物的采食量及能量平衡调控具有明显的作用。除此之外,瘦素对生殖系统也有着重要的调节作用。瘦素通过JAK-STAT途径及与KiSS-1/GPR54系统的相互作用,对动物初情期的启动,下丘脑—垂体—性腺(HPG)轴及胎盘与子宫等产生广泛的影响。     

瘦素调节动物采食量及能量代谢的研究进展

下丘脑是动物机体能量代谢的调节中枢,其神经内分泌调节网络的中心环节是感受外周脂肪细胞分泌的瘦素所提供的能量贮存信号,调控下丘脑弓状核内相关蛋白和激素的表达水平,从而调节能量的摄入和消耗,维持机体能量代谢的稳态,能量的摄入离不开采食而通过能量代谢的途径来控制采食量,尤其对于控制繁殖母猪体重显的尤为重要。文章就对瘦素调节动物采食量以及能量代谢的最新研究机制作一综述。     

猪瘦素的研究进展

瘦素的发现促进了我们对脂肪组织和体内能量平衡关系的理解。脂肪细胞产生的瘦索，可能作为代谢的入口。促进生殖轴的功能。在下丘脑的关键区域存在与食欲控制，生殖和生长有关的瘦素受体（OBR）。Prunier和Quesnc的综述可以看出。营养混乱会延迟初情划的发动，影响正常的发情周期，改变LH的分泌。假设调节能量平衡的机制对产生氧化物的代谢信号敏感，并且可能在体脂、繁殖性能和内分泌功能间呈正相关，     

瘦素及其生理功能概述

瘦素是脂肪细胞分泌的一种细胞因子,其分布广泛,在调节机体能量平衡、维持动物正常的发情周期、促进免疫、提高乳蛋白含量和防治人类的心血管疾病等生理、病理多方面发挥着重要的作用.本文综述了瘦素及其受体的结构和特征、瘦素的主要生理功能及其在细胞中的信号转导途径.     

Research Advance on the Relationship between Leptin and Reproduction Activities of Mammal

Studies in the last two decades found that Leptin not only involves in the regulation of mammalian ingestion and energy homeostasis,but also serves as a metabolic signal regulating the mammalian reproduction by acting on the hypothalamic-pituitary-gonadal (HPG) axis,the placenta and the uterus.Leptin gene is one of the most important candidate genes for research on livestock's growth,development and meat quality,and also for research on prolificacy of livestock due to its key role in regulating the mammalian embryo implantation.Therefore,it is of important scientific significance and potential application value in studying functions and mechanisms of Leptin and its receptor gene.This paper is to dwell on how Leptin regulates mammalian breeding activities including the onset of puberty,development of reproductive organs and gonads,secretion of reproductive hormones,and embryo implantation,and also on how some reproduction activities influence the Leptin secretion in the body.     

瘦素与哺乳动物繁殖活动关系的研究进展

近二十年来的研究发现,瘦素除了参与哺乳动物摄食及能量代谢平衡过程的调节外,还作为一种代谢信号,通过作用于下丘脑—垂体—性腺轴、胎盘和子宫等来调控哺乳动物的繁殖过程。瘦素基因不仅是研究家畜生长发育、肉质等性状的重要候选基因,而且由于瘦素在调控哺乳动物胚胎附植过程中扮演的重要角色,它也是研究家畜多胎性状的重要候选基因之一。研究瘦素及其受体基因的功能及作用机制具有重要的科学意义和潜在的应用价值。文章主要就瘦素对哺乳动物初情期的启动、生殖器官及性腺的发育、生殖激素的分泌、胚胎附植等繁殖活动的调控,以及性别与年龄、妊娠与哺乳、繁殖节律等对瘦素分泌的影响等方面进行综述。     

日粮能量水平对五指山猪生长性能、初情期启动及血清激素含量的影响

试验旨在研究不同日粮能量水平对五指山猪生长性能、初情期启动及血清激素含量的影响。选择20头日龄(30±2)d、体重(2.5±0.6)kg、健康的断奶五指山母猪,随机分为2个处理,分别为NRC组(标准组:饲喂基础日粮,按正常的后备母猪饲喂标准量投放饲料)和0.7 NRC组(限饲组:按NRC组70%的投饲量投喂),每个处理10个重复,每个重复1头猪,试验期10周。结果表明,断奶后6~10周时NRC组体重显著高于0.7 NRC组(P<0.05);NRC组平均日增重显著高于0.7 NRC组(P<0.05);日粮能量水平对五指山猪初情期日龄有显著影响(P<0.05),限饲(0.7 NRC)可延缓五指山母猪发情期启动;0.7 NRC组母猪初情期时背膘厚度显著低于NRC组(P<0.05),初情期时0.7 NRC组母猪背膘厚度降低39.7%左右;初情期时,NRC组血清中卵泡刺激素(FSH)、黄体生成素(LH)、雌二酮(E₂)和瘦素(Leptin)含量均显著高于0.7 NRC组(P<0.05)。由此可知,提高日粮能量水平有利于母猪初情期的启动和发情表现。     

Energy intake, body composition and reproductive performance of the gilt

The relationship between age, live weight, body composition and energy status on the onset and maintenance of reproductive activity in females is reviewed. When possible, swine studies have been employed, although, of necessity, much data are drawn from other species. The relationship between age, weight and puberty is controversial. However, from the available data we conclude that neither age nor weight are reliable indices of reproductive development, but that minimum threshold values for these characteristics must be achieved before puberty can occur. Human data provides a strong indication that a minimum adipose to lean tissue ratio is a prerequisite for puberty onset. Limited data from swine support this contention and indeed it may be a superior measure of reproductive development than either age or weight. However, the value of this ratio remains to be defined in pigs, and again it is minimum threshold level, the attainment of which is necessary, but not in itself sufficient, for puberty onset. A positive energy balance seems to be necessary for puberty onset and the maintenance of estrous cycles in some species, but this has not been investigated in swine. The mechanisms whereby adiposity and energy status influences reproduction are discussed. Human studies demonstrate a negative correlation between energy status, body fatness and plasma gonadotrophin levels. Also, adipose tissue has the ability to metabolize sex steroids, aromatizing androgens to estrogens and changing the direction of estrogen metabolism to produce more or less biologically potent estrogens.     

瘦素在动物初情期启动过程中的调节作用

瘦素(Leptin)主要是由脂肪组织分泌的一种蛋白质产物,对动物初次发情有重要的调节作用。作者就Leptin对动物初情期启动的调控,特别是对下丘脑－垂体－卵巢轴及其相关激素的调控作用进行了综述。     

动物性成熟启动的调控机理

 人类的性早熟表现为病理状态,而在动物上,性早熟则是一个在生产上具有重要价值的经济性状。动物性成熟启动是一个复杂的生物学过程,受下丘脑-垂体-性腺轴调控。"允许信号"和"发育时钟"传达了机体生长发育、能量平衡和环境变化信息,决定了性成熟启动前期处于休眠状态的GnRH神经元激活;GnRH神经元抑制性输入减少和兴奋性输入增加引发了高频GnRH脉冲分泌,促进配子形成和性类固醇激素分泌;类固醇激素又通过负反馈通路影响GnRH分泌并促进性行为。神经胶质细胞也参与了性成熟的启动,主要涉及生长因子家族、神经细胞粘合分子和神经接触蛋白。GnRH基因的表观遗传修饰变化可能在动物性成熟启动过程中发挥了重要作用。     

Leptin对动物繁殖机能的影响及其应用前景

Leptin是由脂肪组织分泌的一种“厌食”激素。自1995年发现以来，就成为最活跃的研究领域。它可通过下丘脑或直接作用于卵巢，对动物青春期的发育、生殖器官的发育以及性激素的分泌都有重要的调节作用。本文综述了Leptin的生物学特性、作用机理及其在繁殖方面的作用，井指出了它在畜牧生产中应用前景。     

饲粮能量对后备母猪初情期启动的调控作用

母猪营养状况对生殖机能有着重要影响,初情期启动与饲粮能量状况、后备母猪的最低体脂储备是其进入初情期的前提条件.通过科学的营养调控措施,有效满足母猪对饲粮能量的需求,是确保母猪发情正常启动及其后的繁殖周期正常的基本条件.本文主要对母猪发情机制进行阐述,立足调控饲粮中的能量水平和来源2个方面,综述了饲粮能量状况对母猪发情的...     

Effects of nutrition and season on the onset of puberty in the beef heifer.

Age at puberty is a major determinant of lifetime reproductive efficiency of beef cows. Research conducted during the past 20 yr has documented the major endocrine events leading to first ovulation in heifers. The critical event seems to be a prepubertal increase in pulsatile LH secretion. Environment influences timing of puberty onset in beef heifers. Nutrition and season are two of the better-defined variables that have been studied. Age at puberty is related inversely to plane of nutrition. The effect of nutrition on sexual maturation involves effects on timing of the prepubertal increase in LH secretion and seems to involve the LH pulse generating system located in the hypothalamus. The precise mechanism by which nutrition influences pulsatile LH secretion has not been elucidated, but signals reflecting metabolic status seem to be involved. Seasonal conditions of the early (birth to 6 mo of age) and late (6 to 12 mo of age) postnatal periods also influence timing of puberty onset in the heifer. Autumn-born heifers attain puberty at younger ages than do spring-born heifers, and exposure to spring-summer temperatures and photoperiods during the second 6 mo of life reduces age at puberty regardless of season of birth. Photoperiod may be the major seasonal cue that influences puberty onset in cattle. Limited evidence suggests that melatonin, a pineal hormone, is involved with transducing photic stimuli into neuroendocrine signals that influence LH secretion. If the physiological mechanisms mediating the effects of nutrition and season on timing of puberty onset are determined, then management strategies for reducing age at puberty can be enhanced.