哺乳动物下丘脑-垂体-卵巢轴的研究进展

哺乳动物的下丘脑、垂体和卵巢分泌的激素在功能上相互作用,构成一个完整的神经内分泌生殖调节体系,即下丘脑垂体卵巢轴,它在生殖活动中起着主要的调节作用。下丘脑中分布的GnRH神经元可以分泌GnRH,GnRH调节垂体中促性腺激素细胞分泌促性腺激素FSH和LH,促性腺激素作用于卵巢受体,引起雌激素和孕酮分泌并影响生殖活动。从组织学角度上研究,下丘脑垂体卵巢轴中的结构,如GnRH神经元、促性腺激素细胞、卵泡随周期性变化而呈现出不同的形态结构和分泌特点。因此,对以上各种细胞的研究是探讨其所分泌激素的基础,而下丘脑垂体卵巢轴中的各种激素的研究则是了解和控制动物繁殖机能的关键。     

GnIH和Inhibin A对鸡胚垂体细胞生殖因子表达与分泌的影响

促性腺激素抑制激素(GnIH)和抑制素(Inhibin)均能通过负调控垂体促性腺激素的分泌来调控禽类繁殖性能,但其中的具体机制及两者在垂体中作用关系仍不清楚。本文以原代培养的鸡胚垂体细胞为研究对象,研究添加GnIH和Inhibin A对垂体细胞生殖相关因子的表达与分泌的影响,以揭示GnIH和Inhibin A分别调控垂体促性腺激素的机制及相关关系。结果显示,0.1 ng/mL GnIH处理能显著抑制垂体细胞分泌FSH和LH,但10 ng/mL GnIH处理时FSH、LH和PRL均无显著变化;GnIH处理对催乳素受体(PRLR)的mRNA表达具有显著的促进作用,对促卵泡素β亚基(FSHβ)、促黄体素β亚期(LHβ)、促性腺激素抑制激素受体(GnIHR)和促性腺激素释放激素受体(Gn RHR)mRNA水平则无影响。80 pg/mL Inhibin A处理垂体细胞12 h后能显著提高FSH的分泌水平,对PRL的分泌水平无显著差异(P0.05);能显著抑制LHβ表达(P0.05);对催乳素(PRL)、GnIHR、催乳素受体(PRLR)、抑制素受体(TGFBR3)的表达则无显著差异(P0.05)。研究结果表明,GnIH能抑制垂体细胞促性腺激素的分泌,Inhibin A能抑制垂体细胞LHβ基因表达,两者均通过垂体促性腺激素发挥生殖调控作用,但两者间无直接关系。     

哺乳动物促性腺激素细胞研究进展

哺乳动物促性腺激素细胞的增殖分化受多种因子影响,它分泌的促性腺激素在生殖调控中占有中心地位。文章系统地介绍了促性腺激素细胞的组织胚胎学研究、促性腺激素细胞分泌的促卵泡素和促黄体素的基因表达调控、分泌调节和合成代谢的研究情况,为研究生殖内分泌提供系统的资料。     

外源性生殖激素在狐繁殖上的应用

动物体内的生殖激素有10余种,由脑垂体、性腺等分泌。外源生殖激素是指人们根据生殖激素的化学结构人工合成或从动物的组织器官中分离提取后,注入狐体内,而非狐体自身合成的生殖激素。目前,在狐的繁殖方面主要应用以下4种外源性生殖激素。1孕马血清促性腺激素(PMSG)它是一种比较特殊的促性腺激素,由糖蛋白组成,其同一分子具有促卵泡素(FSH)和促黄体素(LH)两种活性。因此,具有促滤泡成熟和促排卵的作用。近年来,在大家畜人工授精和胚胎移植技术方面,常用PMSG促同步发情和超数排卵。对狐主要用在促进发情、排卵及人工授精时的同步发情技…     

褪黑素调控动物生殖内分泌的研究进展

褪黑素(MLT)是松果体分泌的一种神经内分泌激素,具有参与免疫反应、调节生命活动的节律性等多种生物学功能,并与生殖内分泌息息相关。目前对于褪黑素的研究主要集中在人类的癌症和植物等方面,而关于动物生殖内分泌的研究较少,深度较浅。研究表明,褪黑素可以调控动物下丘脑-垂体-性腺轴生殖相关激素的内分泌作用,抑制或促进促性腺激素释放激素(GnRH)、促卵泡素(FSH)、促黄体素(LH)、性腺激素的分泌。而在不同物种间,褪黑素作用效果却不同。论文综述了褪黑素对促性腺激素释放激素、促卵泡素、促黄体素、性腺激素以及其他与生殖相关激素的调控,为褪黑素调控动物生殖内分泌的的研究提供参考,以期对褪黑素在动物生殖调控中的作用更深入了解。     

抑制素及其对动物繁殖的影响

抑制素是二聚体糖蛋白激素,是机体分泌的一种能够调节促性腺激素分泌的活性物质,能够提高家畜的排卵率和繁殖力。抑制素抗原免疫可以提前动物发情,有效提高雌性动物的排卵率,对雄性动物生殖功能也起到重要的作用,因而研究抑制素对动物繁殖的影响,对于提高动物的生殖潜力有着很好的应用前景。     

母牛常用生殖激素的临床应用

近年随着产奶水平的不断提高,在一些高产奶牛群中,因生殖激素失调而引起的繁殖障碍亦有所增多。在临床治疗内分泌紊乱的不孕母牛过程中,由于缺乏对生殖激素的全面了解,而使用不当,不能取得预期效果,甚至出现一些不良反应。现将本场近年来母牛常用生殖激素的临床使用方法简介如下。1母牛常用的生殖激素种类1.1来自下丘脑的促性腺激素释放激素(GnRH)其主要功能为:促进和调节脑垂体前叶的分泌和释放促黄体素(LH)、促卵泡素(FSH)。临床用药以LRH-A3(促排Ⅲ)为多。1.2来自垂体前叶的促性腺激素主要有两种:一是促进卵泡发育和成熟的促卵泡素(…     

促性腺激素抑制激素的研究进展

促性腺激素抑制激素(GnIH)是近年在鸟类首先发现的一种神经肽,C端具有精氨酰-苯丙酰胺(RF酰胺),GnIH及其受体在脑和多种器官分布,具有抑制促性腺激素合成和分泌、刺激摄食等作用。在哺乳动物发现C端具有RF酰胺的多肽,为鸟类GnIH类似物,具有相似的作用和组织分布。本文对GnIH的发现、结构、受体、分布定位、生理功能和作用机制进行了综述。     

动物促性腺激素的介绍

1垂体促性腺激素垂体是重要的神经内分泌器官,可以分泌多种蛋白质激素来调节动物的生长、发育、代谢,以及生殖活动。现已发现腺垂体至少分泌7种激素,即生长激素、促肾上腺皮质素、促甲状腺素、促乳素、促卵泡素、促黄体素、粗黑色细胞素。     

促性腺激素细胞的研究进展

哺乳类和鱼类的促性腺激素(GTH)细胞都是位于腺垂体,所分泌的激素有促卵泡激素(FSH)和促黄体素(LH),促卵泡激素可以促成卵细胞和精子的生成,而促黄体素可以促进孕酮和睾酮的产生,关于促性腺激素细胞的来源有三种假说,在所有的对促性腺激素细胞调节控制的因素中,最重要的是促性腺激素释放激素(GnRH)。文章从促性腺激素细胞的定位、功能、源泉细胞,以及对其调节控制等方面的研究进展作一综述,以期为在实践中加强对动物生殖规律的人工调控提供参考。     

Swainsonine Affects the Secretion of Reproductive Hormones by Inhibiting N-glycan Processing

Swainsonine (SW) can cause disorders of reproductive hormones. Gonadotropins are glycoprotein hormones, so they are regulated by N-glycosylation modifications. ɑ-mannosidase, a key enzyme that accelerates the processing of N-glycosylation modifications, can be inhibited by SW. So how does SW affect the structure of N-glycan and the secretion performance of reproductive hormone is unclear. Thus, this test was conducted by intraperitoneal injection of SW exposed mice to establish models of poisoning. The changes of N-glycan structure in their pituitary tissues were detected by MALDI-TOF-MS mass spectrometry; the activity of glycosylase, the level of reproductive hormone, the quantity of reproductive hormone receptors were analyzed. With the extension of injection time, the five composite glycosides of the pituitary glycoprotein in the poisoned group disappeared, and three hybrid glycosides were added. The activities of glycosyltransferase and glycosidase in the poisoned group were significantly decreased. There were further found that the expression levels of gonadotropin receptor, estradiol and progesterone receptor proteins in the poisoned group were significantly lower than those in the control group, and the secretion levels of reproductive hormones were also significantly decreased. SW can significantly inhibit the activity of N-glycan glycosylase and cause changes of normal N-glycan structure; it has a negative influence on the activities of gonadotropins and their receptors, causing the regulation of downstream steroid hormone secretion out of balance, and eventually, reproductive hormone regulation can be disrupted.     

Avian reproductive endocrinology.

Hypothalamic-releasing factors regulate the secretion of anterior pituitary hormones. The anterior pituitary gland secretes the same six hormones as found in mammals: FSH, LH, prolactin, GH (somatotropic hormone), ACTH, and TSH, plus the melanotropic hormone. The endocrine hormones of the avian posterior pituitary gland concerned with reproduction are mesotocin and AVT. The pineal gland, through the secretion of the hormone melatonin, modulates the periodic autonomic functions of the central nervous system. The ovary produces estrogens, progestogens, and androgenic compounds. The testes produce testosterones and progesterone. The thyroid glands produce two hormones, T4 and T3. The avian adrenal glands produce corticosterone and aldosterone. The bursa of Fabricius is considered an endocrine organ since it is involved in the production of humoral factors. The male reproductive system undergoes hormonal changes associated with puberty, the breeding season, and molt. Some avian species undergo a type of disintegration and seasonal reconstruction of the testis and epididymis. The relationship of the ovarian follicular hormones and the plasma hormones varies depending on the stage of the reproductive cycle and the seasonal photostimulation. Female birds may conceive in the absence of a mate as a result of the fertile period phenomena. The blood chemistry of laying birds is different from that seen in nonlaying hens. Domestication has had a definite influence on the hormone cycles of some avian species. This may lead to certain reproductive problems.     

抑制素免疫在动物繁殖中应用的研究进展

抑制素是性腺分泌的一种糖蛋白激素，它具有抑制垂体促卵泡素合成和分泌的作用。抑制素具有免疫反应性，抑制素免疫在提高动物繁殖性能方面有良好的应用前景。作者阐述了抑制素的结构和特性以及抑制素免疫的机理、类型、方法和影响因素及其在畜牧业中的应用。     

抑制素、活化素和卵泡抑素研究进展

抑制素、卵泡抑素和活化素是3种参与垂体促卵泡素调控过程的糖蛋白激素,随着对促卵泡素调控过程的深入了解,发现这3种蛋白在动物生殖周期中发挥着重要的作用。文章主要就抑制素、卵泡抑素和活化素的结构特征、生理功能以及抑制素和卵泡抑素对活化素生物学活性的抑制机理进行了综述。     

The anterior pituitary gland: lessons from livestock

There has been extensive research of the anterior pituitary gland of livestock and poultry due to the economic (agricultural) importance of physiological processes controlled by it including reproduction, growth, lactation and stress. Moreover, farm animals can be biomedical models or useful in evolutionary/ecological research. There are for multiple sites of control of the secretion of anterior pituitary hormones. These include the potential for independent control of proliferation, differentiation, de-differentiation and/or inter-conversion cell death, expression and translation, post-translational modification (potentially generating multiple isoforms with potentially different biological activities), release with or without a specific binding protein and intra-cellular catabolism (proteolysis) of pituitary hormones. Multiple hypothalamic hypophysiotropic peptides (which may also be produced peripherally, e.g. ghrelin) influence the secretion of the anterior pituitary hormones. There is also feedback for hormones from the target endocrine glands. These control mechanisms show broadly a consistency across species and life stages; however, there are some marked differences. Examples from growth hormone, prolactin, follicle stimulating hormone and luteinizing hormone will be considered. In addition, attention will be focused on areas that have been neglected including the role of stellate cells, multiple sub-types of the major adenohypophyseal cells, functional zonation within the anterior pituitary and the role of multiple secretagogues for single hormones.     

Sexual Activity Influences the Secretion of Reproductive Hormones in the Stallion

Contents The aim of this study was to investigate the effect of sexual activity on concentrations of reproductive hormones in plasma of stallions. In the first experiment, two groups of stallions were monitored for secretion of luteinizing hormone (LH), testosterone and oestradiol from the beginning until shortly after the end of the breeding season. One group of animals were reserve stallions not used for breeding (group 1, n = 10), the other group consisted of active breeding sires (group 2, n = 8). Blood samples were withdrawn from March to August at 14-day intervals. In sexually nonactive stallions (group 1), seasonal variations in LH, testosterone and oestradiol occurred and concentrations of these hormones reached a maximum in May (p < 0.05). In the breeding stallions (group 2), no significant changes in the concentrations of these hormones were found between March and August. Concentrations of LH and testosterone were significantly lower in breeding stallions than in reserve stallions at most blood sampling times (p < 0.05). In the reserve stallions, oestradiol concentrations were significantly higher than in the breeding stallions in April and in June (p < 0.05). In a second experiment, the effect of regular sexual activity (semen collection three times per week) on the concentration of LH, testosterone and oestradiol was tested in a group of breeding stallions after a period of sexual rest for several weeks. Blood samples were taken once daily starting the day before the first semen collection was performed. Testosterone concentration significantly decreased in the first days after semen collection started (p < 0.05), while LH secretion was only transiently decreased and no effects on oestradiol concentration were found. In both experiments, semen parameters were within the normal range of fertile stallions. No correlations between the sexual drive of the stallions and concentration of reproductive hormones occurred. It can be concluded that in the stallion the secretion of reproductive hormones is influenced by sexual activity. Regular semen collection seems to inhibit testosterone release by unknown mechanisms while the effects on LH and oestradiol secretion are less pronounced.     

Clinical use of GnRH agonists in canine and feline species

GnRH (gonadotrophin releasing hormone) is a key hormone of reproductive function in mammals; agonist forms have been largely developed, and data concerning their use in small animal reproduction are now abundant. GnRH agonists act by a two-step mechanism. First, their agonist properties on the pituitary will cause marked LH (luteinizing hormone) and FSH (follicle-stimulating hormone) secretion into the bloodstream, accompanied by an increase in the concentrations of sex steroid hormones. Then, in case of constant administration, GnRH agonists will lead to pituitary desensitization, and FSH and LH levels will collapse. These two effects have been widely documented, and these compounds have many potential benefits in a clinical context, capitalizing both on their stimulating and sterilizing effects.     

miR-93对延边黄牛垂体细胞GH分泌的影响

为了分析血液外泌体miRNA对延边黄牛垂体细胞生长激素（GH）分泌的影响,试验选择在延边黄牛和韩延牛血液外泌体中存在显著差异表达的miR-93,分析其对延边黄牛垂体细胞GH分泌的影响机制。试验首先进行延边黄牛垂体细胞的原代培养,之后将miR-93的mimics（miR-93-mi组）、mimics对照品（NC对照组）、inhibitor（miR-93-in组）、inhibitor对照品（iNC组）转染给已建立的垂体原代细胞,48 h后收集细胞,提取总mRNA和总蛋白。试验利用targetscan和RNAhybrid分析软件对miR-93的靶基因进行预测,并利用双荧光素酶报告基因系统对miR-93的靶关系进行验证;利用实时荧光定量PCR和Western blotting技术分别检测靶基因mRNA转录和蛋白的表达情况,结果表明,miR-93靶向了生长激素释放激素受体（GHRHR）的3'UTR;与NC对照组比较,miR-93-mi组的延边黄牛垂体细胞中GH mRNA转录和蛋白表达均极显著低于NC对照组（P<0.01）;miR-93-mi组的GHRH mRNA转录和蛋白表达均极显著低于NC对照组（P<0.01）,而miR-93-in组的GHRHR蛋白表达显著高于iNC对照组（P<0.05）。说明miR-93可通过调节GHRHR的表达而调控延边黄牛垂体细胞GH的分泌,进而调控延边黄牛的生长发育。     

日粮能量对育成柴鸡外周血浆促性腺激素与垂体分泌促性腺激素的影响

采用单因素方差随机试验,选用14周龄育成柴鸡36只,随机的分成3个处理,每个处理3个重复,每个重复4只鸡,分别饲喂低能、对照、高能的日粮,试验期为28d。结果显示,育成柴鸡外周血浆FSH浓度,低能、对照与高能差异极限著（P〈0.01）,并且随着日龄增加FSH浓度逐渐增加。育成柴鸡外周血浆LH浓度第1周时低能组与对照、高能组差异极显著（P〈0.01）,对照与高能组差异不显著;第2、3周处理低能组、对照、高能组差异极显著（P〈0.01）,并且随着日龄增加浓度增加。育成柴鸡体外培养垂体细胞分泌FSH、LH高能组与低能、对照组差异极显著（P〈0.01）,而低能组与对照组差异不显著。结果表明,日粮能量通过下丘脑-垂体-性腺轴影响育成柴鸡生殖机能。     

家养动物FSHR基因的结构功能与表达调控研究进展

促卵泡激素FSH及其受体在卵巢的卵泡发育和激素生成以及睾丸的精子生成中起关键的调节作用。促卵泡激素受体FSHR与家养动物的繁殖能力有密切关系。提高家畜产仔率是确保我国动物养殖业持续健康发展的主要方向。已有研究表明,FSHR基因对动物的卵巢卵泡生长发育和精子发生具有巨大的调控作用,并且该基因与家养动物的繁殖性状,繁殖能力存在一定的关联性。本文章旨在介绍FSHR的结构,表达和生物学功能,以及在家养动物(牛,绵羊,山羊,猪和鸡)方面的研究展开综述,并且对其存在的问题及发展方向提出展望。