促性腺激素抑制激素对动物繁殖的影响

促性腺激素抑制激素(Gn IH)是首次发现于日本鹌鹑下丘脑的神经肽,通过一种G蛋白偶联受体(GPR147)作用于垂体及Gn RH神经元,从而降低促性腺激素合成和释放、抑制性腺发育和维持。本文结合Gn IH的分布特点以及在性腺细胞中的作用方式,阐述了影响动物Gn IH合成与表达的影响因素以及其对不同种类动物的生殖的调控作用,表明Gn IH在动物的繁殖活动中扮演重要的角色,为临床上对动物的生殖调控提供理论基础。     

促性腺激素释放激素的研究进展

促性腺激素释放激素(Gn—RH)自1971年Shally和Guillenmin从猪下丘脑首先分离、提纯、并鉴定为促性腺激素释放激素，随着不断地深入研究，人们发现Gn—RH分布很广，除下丘脑外，还分布在胎盘绒毛、胰腺癌和乳腺癌组织、消化道、胸腺等多种组织中，而且对其结构、功能、合成、分泌等有了更深的认识，在生产中的运用也越来越广泛。     

牦牛卵巢囊肿的诊治

牦牛排卵失败最重要的原因是卵巢囊肿病,该病主要与牦牛产奶量高、年龄、外源性雌激素有关,通常采用全身检查、直检诊断和阴道检查进行诊断。人绒毛膜促性腺激素(HCG)、促性腺激素(Gn RH)或Gn RH类似物这3种药物可对该病进行防治。     

卵泡闭锁的研究新进展

卵泡闭锁是雌性动物重要的生理过程 ,通过内分泌、自分泌和旁分泌等途径 ,受激素 ( Gn RH、FSH、LH、GH、雌激素和雄激素等 )和细胞因子 ( IGFs、TGFs、EGF和 IL-1等 )等多种因素的综合调节。     

同期发情处理在安化本地水牛繁殖的应用

为研究同期发情处理对安化本地水牛繁殖性能的影响,试验分别采用定时输精法、不同激素处理进行同期同期发情处理,并对比青年牛与经产牛对同期发情效果的差异。结果表明:注射Gn RH后18h~20h定时输精和注射Gn RH后观察发情症状适时输精的受胎率为分别为23.53%和37.04%;在同期发情处理后,在第一次配种后注射h CG、LRH-A3或Gn RH,受胎率分别为32.43%、29.17%和38.46%,对照组受胎率为21.05%;青年母牛的同期发情率为51.52%,显著低于经产牛的73.58%,青年母牛和经产牛配种受胎率和总体受胎率分别为47.06%、24.24%和46.15%、33.96%。因此,在安化水牛上适时输精要优于定时输精,第一次配种后注射一定剂量h CG和Gn RH能够提高受胎率,同期发情处理应尽量选择经产牛。     

拉萨市奶牛性控冻精的试验效果

在拉萨市达孜区、曲水县、林周县开展性控冻精试验,采用"Gn RH类似物+促性腺激素"两次注入法进行奶牛的同期发情处理后用性控精液进行人工授精,同期发情率平均为95. 45%,受胎率平均为32. 95%,母犊出生比率最高为100%,平均可达89. 66%。采用Ⅰ组的处理方案较好(即:两次臀部肌注600单位Gn RH,7d后臀部肌注PG,再隔48h肌注Gn RH,发情后早晚间隔12h进行定时人工授精2次),可获得97. 14%的发情率、42. 86%的受胎率和93. 33%的母犊出生率,值得在拉萨推广和实用。     

同期排卵-定时输精对产后难配泌乳奶牛繁殖效率的影响

本试验旨在研究同期排卵-定时输精技术对产后难配泌乳奶牛繁殖效率的影响。选择88头健康、膘情适中、产后不发情或久配不孕(难配)的荷斯坦泌乳奶牛,随机分为3组,分别按照Ovsynch、CIDR+Ovsynch或CIDR+PG+Gn RH程序进行激素处理和定时人工授精,CIDR+Ovsynch或CIDR+PG+Gn RH试验组分别在埋栓、撤栓、第二次注射Gn RH和定时输精时采集10头奶牛血样,测定血清中孕酮(P4)和雌激素(E2)含量。结果表明:3种同期排卵-定时输精程序处理后都可以使一定数量的难配泌乳奶牛配种妊娠,且3种程序对产后难配泌乳奶牛人工授精后的不返情率无显著影响(P0.05);CIDR+Ovsynch试验组泌乳奶牛人工授精后的情期受胎率(46.7%)高于Ovsynch组(28.6%)和CIDR+PG+Gn RH组(26.7%),但差异不显著(P=0.08,P=0.06);CIDR+Ovsynch或CIDR+PG+Gn RH程序处理过程中,泌乳奶牛血清中P4含量的变化趋势一致,E2含量的变化趋势因程序开始处理时奶牛所处的发情周期阶段不同而不同,但两种程序配种妊娠奶牛定时输精时血清中E2含量均极显著高于配种未妊娠奶牛(P0.01)。因此,同期排卵-定时输精技术可用于产后难配泌乳奶牛的配种处理。     

繁殖季节和非繁殖季节生殖激素处理空怀母马效果观察

研究旨在通过多种激素处理确定生殖激素对繁殖母马的处理效果。用不同激素分别对非繁殖季节(8—10月)的11匹空怀伊犁母马和繁殖季节(5—7月)的53匹空怀伊犁母马进行处理。在非繁殖季节,处理前后,用B-型超声波诊断仪每日扫描马两侧卵巢一次,记录卵泡数量,测量卵泡直径;在繁殖季节,通过直肠触摸判定马卵巢的卵泡发育状态。结果表明:母马对促卵泡素(FSH)、孕马血清(e CG)的处理不敏感,并且卵泡35 mm的马对人绒毛膜促性腺激素(h CG)的处理不敏感;氯前列烯醇(PG-cl)对马黄体有溶解功能,马垂体提取物(extracts of equine pituitary glands)可以显著增加大卵泡直径;对于排卵延迟马的治疗效果,人绒毛膜促性腺激素(h CG)作用促黄体素(LH)作用促排-3(Gn RH analogy)号作用。结论:氯前列烯醇(PG-cl)、马垂体提取物、人绒毛膜促性腺激素(h CG)、促黄体素(LH)和促排-3(Gn RH analogy)可以用于空怀母马,调控卵巢功能。     

GnIH/GnRH对鸟类排卵的调控作用

鸟类卵泡的发育受下丘脑-垂体-性腺(Hypothalamic-pituitary-gonadal,HPG)轴调控,其中,下丘脑是调控各器官活动的中枢,促性腺激素抑制激素(Gonadotropin-inhibitoryhoromne,Gn IH)和促性腺激素释放激素(Gonadotropin-releasing hormone,GnRH)是下丘脑中分泌的两种神经肽,GnRH可以促进垂体中促性腺激素的释放,而Gn IH则起着与其相反的作用,GnIH/GnRH激素在鸟类的排卵调控中起着重要作用。文章对GnIH/GnRH激素的发现、分布、结构、受体以及调控等方面进行了初步探讨。     

两种同期发情处理方法对奶水牛繁殖率的影响

为提高奶水牛繁殖率,通过应用CIDR+PG法和Gn RH+PG法对德宏州奶水牛实施了同期发情定时输精试验。结果表明:两种方法的同期发情率和受胎率分别为87.7%和69.4%、41.8%和30.6%,CIDR+PG法效果显著优于Gn RH+PG(P0.05)。该技术的示范应用将奶水牛年平均受胎率提高到65%,比前期提高14.5个百分点,产犊间隔也缩短180d。CIDR+PG处理方法更为理想,适于推广。     

GnRH受体在山羊结状神经节的分布

取山羊结状神经节5对,采用免疫组织化学SP法观察促性腺激素释放激素（Gonadotropin releasing hormon,GnRH）受体在结状神经节的分布特点。结果显示,GnRH受体在结状神经节上广泛分布,神经元、卫星细胞、神经纤维、血管肉皮细胞均有不同程度的免疫阳性染色。在神经元胞体中,细胞膜和细胞质有GnRH受体强阳性产物分布,核不着色;卫星细胞、血管内皮细胞也有强阳性产物分布;神经纤维存在弱阳性产物分布。图像分析结果表明,神经元中GnRH受体的相对表达量与其他非神经结构相比差异性显著（P〈0．05）。结果表明,山羊结状神经节中的GnRH受体主要存在于神经元中,山羊结状神经节中的内脏感觉传入神经元对GnRH具有反应性,提示GnRH结状神经节内脏感觉传入神经元的GnRH受体可能作为GnRH对内脏器官的内分泌调节和自主神经对内脏器官的神经调节这2种途径协调作用的节点。     

促性腺激素释放激素受体及其基因表达调控

促性腺激素释放激素（ＧｎＲＨ）在体内的重要功能是由促性腺激素释放激素受体（ＧｎＲＨ－Ｒ）介导的,ＧｎＲＨ及其受体相互作用的调控在繁殖性能调控中是一个关键性位点。本文从ＧｎＲＨ－Ｒ结构与功能,ＧｎＲＨ－Ｒ基因表达调控、ＧｎＲＨ－Ｒ介导的细胞信号转导机制等三个方面对ＧｎＲＨ－Ｒ近年来的研究进展进行了综述了,并展望了ＧｎＲＨ－Ｒ研究的发展趋势和前景。     

The Effects of GABA on embryonic gonadotropin-releasing hormone neurons in rat hypothalamic primary culture

Gonadotropin-releasing hormone (GnRH) neurons arise in the olfactory placode, migrate into the preoptic area (POA), and then extend axons to the median eminence during embryogenesis. Little information is available concerning the properties of GnRH neurons during the late gestational period when GnRH neurons reach the POA and form neuronal networks, although many studies have examined such properties during earlier developmental stages or the postnatal period. The present study was performed to elucidate the involvement of gamma-aminobutyric acid (GABA), one of the major neurotransmitters modifying GnRH neural activity, in regulation of GnRH gene expression on embryonic day 18.5 (E18.5) using transgenic rats expressing enhanced green fluorescence protein (EGFP) under the control of GnRH promoter. First, using RT-PCR, the mRNA of two isoforms of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD), GAD65 and GAD67 was detected in E18.5 embryonic POA-containing tissues. GAD67-positive cells were also demonstrated in close vicinity to GnRH-positive cells by immunohistochemistry, and immunoreactivity for both the GABA-A and GABA-B receptor subunits was detected in GnRH neurons. Next, primary cultures derived from anterior hypothalamic tissue of E18.5 embryos were prepared, and the effects of GABA and its agonists on GnRH promoter activity were evaluated using EGFP expression as a marker. GABA and the GABA-A receptor agonist muscimol, but not the GABA-B receptor agonist baclofen, significantly increased the EGFP-positive/GnRH-positive cell ratio. These results suggest that GABA plays a role in stimulating GnRH gene expression through GABA-A receptors in embryonic GnRH neurons in late gestational stages.     

Neuroendocrine control of reproductive function in ruminants

Gonadotropin‐releasing hormone (GnRH) is a key molecule in the control of reproduction in mammals. It is generally thought that the secretion of GnRH into the pituitary portal vessels is governed by two distinct neural mechanisms: the pulsatile and surge mode centers. The former is called the GnRH pulse generator, and this neural substrate plays a role as the master regulator of the reproductive function. An electrophysiological technique for monitoring the neural activity of the GnRH pulse generator has been established in the Shiba goat. The central actions of several neuropeptides have been assessed using this system. Results suggest that several neuropeptides including neuropeptide Y, cholecystokinin‐octapeptide and melanocortins are involved in the regulation of the GnRH pulse generator activity in the goat. Each input of those neuropeptides likely represents a unique mechanism conveying specific information about changes in the internal and external environments such as olfactory signals, nutrition, stress, and steroidal milieu, to the GnRH pulse generator. Further elucidations of actions of neurotransmitters on the GnRH pulse generator may serve for better understanding of the neuroendocrine control of reproduction in the ruminant.     

Use of GnRH in livestock production--current position and new research data

The hypothalamic gonadotropin-releasing hormone (GnRH) is seen as the key hormone of neuroendocrine regulation of reproduction. The ability of GnRH and its analogues to stimulate the release of the gonadotropins FSH and LH is world-wide utilized for various veterinary purposes, including treatment of certain hormone-dependent disturbances and stimulation of ovulation in controlled breeding programmes. A large difference is striking, however, when comparing the efficiencies reported. This may underline the importance of accurate treatment and reflect the manifold influences by animals and their environment on reproductive performance. During the last years, novel analytical methods have been established enabling a significant progress in reproductive research. The discovery and characterization of natural GnRH variants and their receptors in several vertebrate species may become more important.The reason is, that these GnRHs affect the release of the gonadotropins FSH and LH, but they may transmit, moreover, seasonal and nutritive signals to reproductive organs. It might be expected that the further exploration of these functions may serve as basis for the development of new and effective biotechnical methods in farm animal treatment.     

GnRH依赖型性早熟遗传调控系统研究进展

性早熟在人类上表现为病理状态,而在家禽生产上则是一个具有重要经济价值的性状。人类性早熟调控机理的研究较为透彻,尤其是近年来全基因关联分析方法的应用,使得研究者对于性成熟启动相关新基因发掘及其调控网络的认识更加深入。论文综述了人类Gn-RH依赖型性早熟(GDPP)的5个基因调控系统,包括kisspeptin系统、γ-GABA系统、NPY和leptin系统、LIN28B系统和NKB系统的研究进展,为禽类早熟性状研究提供依据。     

Hypoxia-inducible factor-1alpha and nitric oxide synthases in bovine follicles close to ovulation and early luteal angiogenesis

The objective of the study was to characterize expression patterns of hypoxia-inducible factor-1alpha (HIF1A), inducible nitric oxide synthase (iNOS) and endothelial (eNOS) isoforms in time-defined follicle classes before and after GnRH application in the cow. Ovaries containing pre-ovulatory follicles or corpora lutea were collected by transvaginal ovariectomy (n = 5 cows/group) as follow: (I) before GnRH administration; (II) 4h after GnRH; (III) 10h after GnRH; (IV) 20h after GnRH; (V) 25h after GnRH; and (VI) 60h after GnRH (early corpus luteum). The mRNA abundance of HIF1A in the follicle group before GnRH was high, followed by a significant down regulation afterwards with a minimum level 25h after GnRH (close to ovulation) and significant increase only after ovulation. The mRNA abundance of iNOS before GnRH was high, decreased significantly during LH surge, with minimum levels afterwards. In contrast, the mRNA of eNOS decreased in the follicle group 20h after GnRH, followed by a rapid and significant upregulation just after ovulation. Immunohistochemically, the granulosa cells of antral follicles and the eosinophils of the theca tissue as well of the early corpus luteum showed a strong staining for HIF1A. The location of the eosinophils could be clearly demonstrated by immunostaining with an eosinophil-specific antibody (EMBP) and transmission electron microscopy. In conclusion, the parallel and acute regulated expression patterns of HIF1A and NOS isoforms, specifically during the interval between the LH surge and ovulation, indicate that these paracrine factors are involved in the local mechanisms, regulating final follicle maturation, ovulation and early luteal angiogenesis.     

Integration Between Different Hypothalamic Nuclei Involved in Stress and GnRH Secretion in the Ewe

This study investigated possible integrated links in the neuroanatomical pathways through which the activity of neurones in the paraventricular nucleus and arcuate nucleus may modulate suppression of gonadotrophin‐releasing hormone (GnRH) secretion during stressful situations. Double‐label immunofluorescence and laser scanning confocal microscopy were used to examine the hypothalamic sections from the follicular phase ewes. Noradrenergic terminals were in close contact with 65.7 ± 6.1% corticotrophin‐releasing hormone (CRH) and 84.6 ± 3.2% arginine vasopressin (AVP) cell bodies in the paraventricular nucleus but not with β‐endorphin cell bodies in the arcuate nucleus. Furthermore, γ‐amino butyric acid (GABA) terminals were close to 80.9 ± 3.5% CRH but no AVP cell bodies in the paraventricular nucleus, as well as 60.8 ± 4.1%β‐endorphin cell bodies in the arcuate nucleus. Although CRH, AVP and β‐endorphin cell terminals were identified in the medial pre‐optic area, no direct contacts with GnRH cell bodies were observed. Within the median eminence, abundant CRH but not AVP terminals were close to GnRH cell terminals in the external zone; whereas, β‐endorphin cells and terminals were in the internal zone. In conclusion, neuroanatomical evidence is provided for the ewe supporting the hypothesis that brainstem noradrenergic and hypothalamic GABA neurones are important in modulating the activity of CRH and AVP neurones in the paraventricular nucleus, as well as β‐endorphin neurones in the arcuate nucleus. These paraventricular and arcuate neurones may also involve interneurones to influence GnRH cell bodies in medial pre‐optic area, whereas the median eminence may provide a major site for direct modulation of GnRH release by CRH terminals.