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1.
动物性成熟启动是一个复杂的生物学过程,其决定性事件是下丘脑GnRH脉冲式释放增加。GnRH脉冲式释放增加是由跨突触改变和神经胶质输入两个方面共同引起的,其中,跨突触改变由谷氨酸能神经元、Kisspeptin神经元、γ 氨基丁酸能神经元、阿片能神经元及RFRP神经元提供,而神经胶质输入主要由生长因子家族提供。诸多功能基因参与了性成熟启动过程,组成了复杂的基因调控网络,这些基因并不是按照严格的等级顺序排列,而是在功能上有所重叠。转录调节因子的抑制性作用使得性成熟启动不会提早发生。论文还介绍了表观机制在性成熟启动调控中的重要作用。 相似文献
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哺乳动物下丘脑-垂体-卵巢轴的研究进展 总被引：3，自引：1，他引：3
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。 相似文献
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促性腺激素释放激素(gonadotropin-releasing hormone,GnRH)神经元是控制生殖的主要神经元。下丘脑GnRH神经元的适时激活,兴奋性和抑制性信号跨突触传递的严格控制,决定了性腺发育和成年个体的繁殖能力。研究表明,神经胶质细胞是调控GnRH神经元的主要细胞,神经胶质细胞利用胞体和突起,通过多种细胞和分子机制调控GnRH神经元,包括分泌旁分泌因子调控GnRH神经元,通过黏合分子和具有重塑性的神经胶质细胞覆盖GnRH神经元来完成神经胶质细胞和GnRH神经元之间的接触依赖性通讯。论文对神经胶质细胞调控GnRH神经元活性和分泌的机制进行了综述,以期对神经胶质细胞在生殖调控中的作用有更深入的了解。 相似文献
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Kisspeptin是由KISS1基因编码的一种神经肽。Kisspeptin与其受体是GnRH神经元上游的关键调节因子,通过调控GnRH释放刺激垂体促性腺激素的分泌。Kisspeptin在哺乳动物下丘脑、垂体和性腺等器官组织中表达,参与下丘脑-垂体-性腺(HPG)轴功能调控,在哺乳动物生殖过程中发挥重要作用。文章主要从下丘脑、垂体和性腺三个方面阐述Kisspeptin对哺乳动物生殖功能的调控作用,并就Kisspeptin在动物初情期启动、季节性繁殖和繁殖性能上的研究进行分析总结,以期为Kisspeptin在动物繁殖领域的研究和应用提供参考依据。 相似文献
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繁殖率低是制约马属动物产业发展的瓶颈,繁殖调控技术不完善也是导致该产业发展缓慢的主要因素。促性腺激素释放激素（gonadotropin-releasing hormone,GnRH）是下丘脑分泌产生的神经激素,在下丘脑-垂体-性腺轴通路中起关键作用。GnRH可以有效促进马属动物卵泡发育及排卵。GnRH是具有十肽结构的化合物,通过改变十肽结构中不同位置的氨基酸合成不同的GnRH类似物。GnRH及其类似物可通过刺激卵泡刺激素（follicle-stimulating hormone,FSH）和黄体生成素（luteinizing hormone,LH）的分泌、抑制雌激素受体的合成影响动物繁殖性能。GnRH及其类似物已被证明可提高马属动物的繁殖性能。对GnRH和促性腺激素释放激素受体（gonadotropin-releasing hormone receptor,GnRHR）的结构特点、生物学功能以及GnRH类似物在马属动物繁殖方面的应用研究进展进行综述,以期为探究GnRH生物学作用的分子机制以及GnRH类似物在马属动物繁殖调控中的科学应用提供参考。 相似文献
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性成熟启动是一个复杂的生理过程,受"下丘脑-垂体-性腺"轴控制。决定性成熟启动的关键性事件是下丘脑促性腺激素释放激素(GnRH)脉冲式释放增加,KISS-1基因编码产物Kisspeptin通过其受体GPR54能够直接刺激GnRH释放,进而启动性成熟进程,KISS-1/GPR54系统被认为是性成熟启动的关键看门基因。禽类的KISS-1基因在GenBank中尚未被清晰注释。本文以文昌鸡为素材,采用比较基因组学方法分析了不同物种KISS-1及其上、下游基因在染色体上的分布,确定了鸡chr26:1522493-1532710区域为候选片段,通过PCR扩增和克隆测序获得了该候选片段完整序列(命名为类KISS-1序列);同时,采用BLAST程序搜索出9个同源性在50%~85%的EST序列,通过拼接得到3个延伸EST序列。表达验证分析表明,3个延伸EST序列在文昌鸡下丘脑组织cDNA文库中均有表达。 相似文献
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雌性动物第一次出现发情表现并排卵的时期,称为初情期.当动物到达初情期年龄时,GnRH脉冲释放增加,GnRH能够刺激垂体释放LH和FSH,这两种激素是产生成熟配子和性腺类固醇激素分泌所必需的物质.下面就动物的初情期发生机制及调控初情期的途径和方法做以下介绍. 相似文献
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初情期时,激素脉冲式分泌促使性腺的发育成熟.GPR54(G蛋白偶联受体)与它的配体一起在初情期启动时起着决定性的作用,缺失GPR54的小鼠不能达到初情期,生殖器官发育不成熟,性激素类固醇和促性腺激素水平低,但GnRH的水平正常.在人类,由于GPR54基因突变导致性腺机能衰退.在更小程度上来说,Metastin(肿瘤迁移抑制因子)和GPR54的产量是通过睾酮和雌激素来负调节的.在啮齿目动物上,注射GPR54配体能够增加激素的分泌.因此,可能在GnRH分泌水平上,下丘脑-垂体-性腺轴的正常功能需要GPR54. 相似文献
11.
Tatsuo NAKAHARA Yoshihisa UENOYAMA Akira IWASE Shinya OISHI Sho NAKAMURA Shiori MINABE Youki WATANABE Chikaya DEURA Taro NOGUCHI Nobutaka FUJII Fumitaka KIKKAWA Kei-ichiro MAEDA Hiroko TSUKAMURA 《The Journal of reproduction and development》2013,59(5):479-484
Puberty in mammals is timed by an increase in gonadotropin-releasing hormone (GnRH)
secretion. Previous studies have shown involvement of the two neuropeptides,
kisspeptin and neurokinin B (NKB), in controlling puberty onset. Little is known
about the role of the other key neuropeptide, dynorphin, in controlling puberty
onset, although these three neuropeptides colocalize in the arcuate kisspeptin
neurons. The arcuate kisspeptin neuron, which is also referred to as the KNDy neuron,
has recently been considered to play a role as an intrinsic source of the GnRH pulse
generator. The present study aimed to determine if attenuation of inhibitory
dynorphin-kappa-opioid receptor (KOR) signaling triggers the initiation of puberty in
normal developing female rats. The present study also determined if stimulatory
NKB-neurokinin 3 receptor (NK3R) signaling advances puberty onset. Female
Wistar-Imamichi rats were weaned and intraperitoneally implanted with osmotic
minipumps filled with nor-binaltorphimine (nor-BNI), a KOR antagonist, or senktide, a
NK3R agonist, at 20 days of age. Fourteen days of intraperitoneal infusion of nor-BNI
or senktide advanced puberty onset, manifested as vaginal opening and the first
vaginal estrus in female rats. Frequent blood sampling showed that nor-BNI
significantly increased luteinizing hormone (LH) pulse frequency at 29 days of age
compared with vehicle-treated controls. Senktide tended to increase this frequency,
but its effect was not statistically significant. The present results suggest that
the inhibitory input of dynorphin-KOR signaling plays a role in the prepubertal
restraint of GnRH/LH secretion in normal developing female rats and that attenuation
of dynorphin-KOR signaling and increase in NKB-NK3R signaling trigger the onset of
puberty in female rats. 相似文献
12.
Smith JT 《Domestic animal endocrinology》2012,43(2):75-84
Sheep are seasonal breeders, experiencing an annual period of reproductive quiescence in response to increased photoperiod during the late-winter into spring and renaissance during the late summer. The nonbreeding (anestrous) season is characterized by a reduction in the pulsatile secretion of GnRH from the brain, in part because of an increase in negative feedback activity of estrogen. Neuronal populations in the hypothalamus that produce kisspeptin and gonadotropin-inhibitory hormone (GnIH) appear to be important for the seasonal shift in reproductive activity, and the former are also mandatory for puberty onset. Kisspeptin cells in the arcuate nucleus (ARC) and preoptic area appear to regulate GnRH neurons and transmit sex-steroid feedback signals to these neurons. Moreover, kisspeptin expression in the ARC is markedly up-regulated at the onset of the breeding season, as too are the number of kisspeptin fibers in close apposition to GnRH neurons. The lower levels of kisspeptin seen during the nonbreeding season can be "corrected" by infusion of kisspeptin, which causes ovulation in seasonally acyclic females. The role of GnIH is less clear, but mounting evidence supports a role for this neuropeptide in the inhibitory regulation of both GnRH secretion and gonadotropin release from the pituitary gland. Contrary to kisspeptin, GnIH expression is markedly reduced at the onset of the breeding season. In addition, the number of GnIH fibers in close apposition to GnRH neurons also decreases during this time. Importantly, exogenous GnIH treatment can block both the pulsatile release of LH and the preovulatory LH surge during the breeding season. In summary, it is most likely the integrated function of both these neuropeptide systems that modulate the annual shift in photoperiod to a physiological change in fertility. 相似文献
13.
哺乳动物性晚熟相关基因的研究进展 总被引：1，自引：0，他引：1
人和哺乳动物性的发育和成熟源于下丘脑性腺激素释放激素（gonadotropin releasing hormone,GnRH）脉冲式释放。GnRH释放受到抑制或破坏,就会导致性腺机能减退,人在发育前和发育期就会出现发育迟缓和性发育不良,表现为无精症或闭经;动物则表现为初情期延迟、生殖能力下降等表型。编码促性腺激素及其受体基因的突变可能引起哺乳动物性晚熟。笔者简要介绍了GPR54、GnRH/GnRHR、FSH/FSHR、LH/LHR基因与哺乳动物性晚熟的关系。 相似文献
14.
初情期启动过程中小尾寒羊下丘脑GnRH基因甲基化状态及表达量关系研究 总被引：1，自引：0，他引：1
初情期启动的早晚关系到雌性动物的繁殖性能,GnRH是动物初情期启动过程中的关键基因,其启动子区甲基化状态与GnRH mRNA表达量之间的关系尚不清楚。本研究选择初情期前、临近初情期和初情期雌性小尾寒羊的下丘脑作为样本,利用亚硫酸氢盐测序(BSP)技术和实时荧光定量PCR(qRT-PCR)技术检测了初情期不同阶段小尾寒羊GnRH启动子区的甲基化状态和GnRH mRNA的表达量,并分析二者之间的关系。结果表明:小尾寒羊到达初情期时,GnRH基因启动子区甲基化水平显著降低(P0.05),尤其是在启动子区-570位点降低最明显,而随着初情期的启动GnRH mRNA表达量呈上升趋势。结果提示,初情期启动过程中,GnRH mRNA表达量升高可能与下丘脑GnRH基因启动子区特定位点甲基化水平降低存在一定的关系。 相似文献
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The discovery of the obesity gene and its product, leptin, it is now possible to examine the relationship between body fat and the neuroendocrine axis. A minimum percentage of body fat may be linked to onset of puberty and weaning-to-estrus interval in the pig. Adipose tissue is no longer considered as only a depot to store excess energy in the form of fat. Recent findings demonstrate that numerous genes, i.e., relaxin, interleukins and other cytokines and biologically active substances such as leptin, insulin-like growth factor-I (IGF-I), IGF-II and Agouti protein are produced by porcine adipose tissue, which could have a profound effect on appetite and the reproductive axis. Hypothalamic neurons are transsynaptically connected to porcine adipose tissue and may regulate adipose tissue function. In the pig nutritional signals such as leptin are detected by the central nervous system (CNS) and translated by the neuroendocrine system into signals, which regulate appetite, hypothalamic gonadotropin-releasing hormone (GnRH) release and subsequent luteinizing hormone (LH) secretion. Furthermore, leptin directly affects LH secretion from the pituitary gland independent of CNS input. Changes in body weight or nutritional status are characterized by altered adipocyte function a reduction in adipose tissue leptin expression, serum leptin concentrations and a concurrent decrease in LH secretion. During pubertal development serum leptin levels, hypothalamic leptin receptor mRNA and estrogen-induced leptin gene expression in fat increased with age and adiposity in the pig and this occurred at the time of expected puberty. In the lactating sow serum and milk leptin concentrations were positively correlated with backfat thickness and level of dietary energy fed during gestation as well as feed consumption. Although, these results identify leptin as a putative signal that links metabolic status and neuroendocrine control of reproduction, other adipocyte protein products may play an important role in regulating the reproductive axis in the pig. 相似文献
16.
The neuronal control of fertility and sterility has been a subject of research for years. However, nowadays, in spite of considerable literature about GnRH during the last few decades, the precise cellular and molecular mechanisms whereby gonadal steroids and other peripheral signals converge in the brain to achieve the fine regulation of GnRH secretion remains partially unknown. In this scenario, a major breakthrough in our understanding of the neuronal signals governing reproduction took place in 2003 with the discovery of metastin/kisspeptin as a major player in the control of GnRH secretion. This molecule, first described as having a crucial role in triggering the onset of puberty, is involved in all phases of reproductive life and hence has attracted the interest of many reproductive neuroendocrinologists. Administered either centrally or peripherally, kisspeptin strongly induces the secretion of gonadotropin in many species, mainly through stimulation of GnRH secretion. Kisspeptin cells involved in the control of GnRH secretion are located in two regions of the brain: the preoptic area and the arcuate nucleus. Carrying oestradiol receptor alpha, kisspeptin cells of these regions appear to be the main integration centres for the expression of both the positive and negative feedback of steroid on GnRH secretion. More recently, this molecule has been shown to be able to synchronize preovulatory surges in cyclic ewes and cause ovulation in seasonally acyclic ewes. This review summarizes the most relevant aspects of the role of kisspeptin in GnRH/LH release and the potential application of this molecule in new strategies for controlling female fertility. 相似文献
17.
Leptin plays an important role in signaling nutritional status to the central reproductive axis of mammals and appears to be at least a permissive factor in the initiation of puberty. The expression and secretion of leptin are correlated with body fat mass and are acutely affected by changes in feed intake. Moreover, circulating leptin increases during pubertal development in rodents, human females and heifers. Effects of leptin are mediated mainly via receptor activation of the JAK-STAT pathway; however, activation of alternative pathways, such as MAP kinase, has also been reported. Although the leptin receptor (LR) has not been found on GnRH neurons, leptin stimulates the release of GnRH from rat and porcine hypothalamic explants. Moreover, leptin increases the release of LH in rats and from adenohypophyseal explants and/or cells from full-fed rats and pigs. In contrast, stimulation of the hypothalamic-gonadotropic axis by leptin in cattle and sheep is observed predominantly in animals and tissues pre-exposed to profound negative energy balance. For example, leptin prevents fasting-mediated reductions in the frequency of LH pulses in peripubertal heifers, augments the magnitude of LH and GnRH pulses in fasted cows, and enhances basal secretion of LH in vivo and from adenohypophyseal explants of fasted cows. However, leptin is incapable of accelerating the frequency of LH pulses in prepubertal heifers, regardless of nutrient status, and has no effect on the secretion of GnRH and LH in full-fed cattle or hypothalamic/hypophyseal explants derived thereof. Similar to results obtained with LH, basal secretion of GH from anterior pituitary explants of fasted, but not normal-fed cows, was potentiated acutely by low, but not high, doses of leptin. Mechanisms through which undernutrition hypersensitize the hypothalamic-gonadotropic axis to leptin may involve up-regulation of the LR. However, an increase in LR mRNA expression is not a requisite feature of heightened adenohypophyseal responses in fasted cattle. To date, leptin has not been successful for inducing puberty in ruminants. Future therapeutic uses for recombinant leptin that exploit states of nutritional hypersensitization, and identification of genetic markers for genotypic variation in leptin resistance, are currently under investigation. 相似文献
18.
为研究济宁青山羊生后发育阶段GnRH及GnRHR在下丘脑内的形态学分布和变化规律,采用链霉亲和素-生物素-过氧化物酶复合物(Strept Avidin Biotin-Peroxidase Complex,SABC)免疫组织化学方法,对0、2、4和6月龄雌性济宁青山羊下丘脑中GnRH及GnRHR的分布进行了同步研究。结果显示,GnRH和GnRHR免疫阳性细胞在下丘脑内广泛存在,主要分布于视前内侧区、乳头体、视上核和视交叉上核。随月龄增长,GnRH和GnRHR阳性细胞不断增大,数量不断增多,其中0～2月龄是最快的时期。结果提示,下丘脑分泌的GnRH及GnRHR对生后发育阶段青山羊性成熟的启动及维持有重要作用。 相似文献
19.
To determine whether pituitary concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH) or hypothalamic content of gonadotropin releasing hormone (GnRH) change before puberty, 40 prepubertal gilts averaging 7 mo of age were slaughtered before or on the second, third or fourth day after relocation and boar exposure. Some gilts responded to relocation and boar exposure as indicated by swollen vulvae, turgid uteri and enlarged ovarian follicles at the time of slaughter. Pituitary concentrations of LH and FSH and hypothalamic content of GnRH were similar between gilts that responded to relocation and boar exposure and gilts that did not respond. In addition, boar exposure and relocation had no effect on pituitary concentrations of LH and FSH or on hypothalamic content of GnRH. To determine whether pituitary responsiveness to GnRH changes before puberty, a third experiment was conducted in which 72 gilts were injected with 400 micrograms of GnRH either before or on the second, third or fourth day after relocation and boar exposure. In gilts that subsequently responded (i.e., ovulated) as a result of relocation and boar exposure, pituitary responsiveness to GnRH was reduced as compared with gilts that failed to ovulate after relocation and boar exposure. Peak concentrations of serum LH after GnRH injection were 4.6 +/- 1.3 vs 9.8 +/- .8 ng/ml for responders vs nonresponders. Peak serum FSH after GnRH injection was also lower for responders than for nonresponders (29.5 +/- 4.2 vs 41.2 +/- 2.4 ng/ml). When compared with controls, relocation and boar exposure did not significantly affect GnRH-induced release of LH and FSH.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献