体外无血清培养牛垂体细胞分泌催乳素的调节—性腺激素的作用

本实验对牛垂体混合细胞进行24小时体外无血清培养,对其分泌催乳素的功能进行了观察,并分别在培养介质中加入0、1、10、100ng/ml的孕酮、脱氢表雄酮、雄烯二酮、雌二醇和睾酮,用放射免疫测定法测定培养液介质中催乳素含量,以研究这些性腺激素和中间产物对垂体细胞分泌催乳素的影响。结果表明:孕酮对离体牛垂体细胞无血清培养条件下分泌催乳素的功能没有影响。而脱氢表雄酮、雄烯二酮、睾酮和雌激素均引起催乳素分泌量显著升高,说明这些性腺类固醇激素对牛垂体细胞离体培养分泌催乳素具有促进作用,可能是垂体前叶催乳素分泌调节的重要组成部分。     

GnRH脉冲对体外原代培养大鼠GTH细胞中 LHβ mRNA表达水平的影响

研究不同脉冲频率GnRH对GTH细胞分泌LH的影响。利用细胞体外培养技术结合荧光定量PCR技术,对体外培养的大鼠原代垂体细胞在不同脉冲频率GnRH刺激下,细胞LHβ mRNA的变化进行了研究。在相同振幅条件下,高频刺激(30 min间隔)时,LHβ mRNA表达水平达到高峰。结果表明,高频脉冲主要引起LH的表达,支持了GnRH脉冲频率本身就是一个调控信号的假说。     

LRH—A3,hCG和PMSG对体外培养条件下牦牛垂体组织LH和FSH分泌的调节

促卵泡素３号（ＬＲＨ－Ａ３）、人绒毛膜促性腺激素（ｈＣＧ）和孕马血清促性腺激素（ＰＭＳＧ）等３种外源性激素均可增加体外培养条件下牦牛垂体组织分泌ＬＨ和ＦＳＨ的能力。培养液中ＬＨ和ＦＳＨ含量与加入的ＬＲＨ－Ａ３量呈正相关，与加入的ＰＭＳＧ和ｈＣ的量无显著关系。     

初情期前母猪垂体细胞LH和FSH的释放及其对GnRH类似物的反应

利用垂体细胞单层培养模型研究了30,60,90,120和150日龄北京黑猪母猪垂体细胞LH和FSH的释放及其对LRH－A3反应能力。结果表明,猪垂体细胞LH和FSH释放对LRH－A3的反应呈S形剂量依赖型同线。LH基础释放量和LRH－A3刺激的最大释放量在不同日龄间没有显著差异,说明初情期前母猪垂体细胞已达最大LH释放和对GnRH反应的能力。FSH的基础释放量和LRH－A3刺激的最在释放量在30日龄与60日龄之间无差异,但90日龄以后垂体细胞FSH的释施量随日龄增大而降低,提出可能由于垂体在体内时受过抑制素的作用。     

褪黑素对体外培养绵羊垂体细胞分泌FSH和LH的影响

本文采用体外细胞培养和放射免疫测定法(RIA)的方法,研究了褪黑素(MLT)对季节性繁殖的蒙古母羊垂体细胞分泌促卵泡素(FSH)和促黄体素(LH)的作用。结果表明:当单独用递增的MLT(10、100、1000、2000pg/mL)处理原代垂体细胞时,随时间的延长FSH的分泌量极显著下降(P<0.01),但对LH的基础分泌没有影响;无论用10IU/mLhCG单独刺激,还是用不同剂量MLT与10IU/mLhCG共同刺激垂体细胞,FSH和LH的分泌都极显著高于对照组(P<0.01),但与MLT的剂量没有关系。     

褪黑素对体外培养绵羊垂体细胞分泌FSH和LH的影响

本文采用体外细胞培养和放射免疫测定法(RIA)的方法,研究了褪黑素(MLT)对季节性繁殖的蒙古母羊垂体细胞分泌促卵泡素(FSH)和促黄体素(LH)的作用.结果表明当单独用递增的MLT(10、100、1000、2000 pg/mL)处理原代垂体细胞时,随时间的延长FSH的分泌量极显著下降(P<0.01),但对LH的基础分泌没有影响;无论用10IU/mLhCG单独刺激,还是用不同剂量MLT与10IU/mLhCG共同刺激垂体细胞,FSH和LH的分泌都极显著高于对照组(P<0.01),但与MLT的剂量没有关系.     

五龙鹅GnRH、PRL和FSHβ因多态性与产蛋性状相关研究

本试验对五龙鹅促性腺激素释放激素(GnRH)、催乳素(PRL)和促卵泡激素β亚基(FSHβ)基因进行多态性检测,并分析其与产蛋性状的关系.选产蛋高峰期五龙鹅100只,采取个体圈养方式饲养,记录个体产蛋量.结果显示,FSHβ外显子3存在1个SNP位点产生3种基因型AA、AB、BB,产蛋量呈现AA型＞AB型＞BB型趋势;PRL内含子2上存在1个SNP位点产生3种基因型CC、CD、DD.CC型、CD型、DD型的开产日龄、开产蛋重、平均蛋重之间差异不显著(P＞0.05),CD型、DD型的产蛋总量显著高于CC型(P＜0.05);GnRH基因5′端调控区存在1个SNP位点产生2种基因型EE、EF型,EF型的开产日龄、开产蛋重、平均蛋重都要高于EE型,但是二者之间差异不显著(P＞0.05),EE型的产蛋总量显著高于EF型(P＜0.05).     

五龙鹅GnRH、PRL和FSHβ基因多态性与产蛋性状相关研究

本试验对五龙鹅促性腺激素释放激素(GnRH)、催乳素(PRL)和促卵泡激素β亚基(FSHβ)基因进行多态性检测,并分析其与产蛋性状的关系。选产蛋高峰期五龙鹅100只,采取个体圈养方式饲养,记录个体产蛋量。结果显示,FSHβ外显子3存在1个SNP位点产生3种基因型AA、AB、BB,产蛋量呈现AA型>AB型>BB型趋势;PRL内含子2上存在1个SNP位点产生3种基因型CC、CD、DD。CC型、CD型、DD型的开产日龄、开产蛋重、平均蛋重之间差异不显著(P>0.05),CD型、DD型的产蛋总量显著高于CC型(P<0.05);GnRH基因5′端调控区存在1个SNP位点产生2种基因型EE、EF型,EF型的开产日龄、开产蛋重、平均蛋重都要高于EE型,但是二者之间差异不显著(P>0.05),EE型的产蛋总量显著高于EF型(P<0.05)。     

LRH─A3、hCG和PMSG对体外培养条件下牦牛垂体组织LH和FSH分泌的调节

促卵泡素３号（ＬＲＨ－Ａ３）、人绒毛膜促性腺激素（ｈＣＧ）和孕马血清促性腺激素（ＰＭＳＧ）等３种外源性激素均可增加体外培养条件下牦牛垂体组织分泌ＬＨ和ＦＳＨ的能力。培养液中ＬＨ和ＦＳＨ含量与加入的ＬＲＨ－Ａ３量呈正相关，与加入的ＰＭＳＧ和ｈＣＧ的量无显著关系     

妊娠期山羊腺垂体中催乳素促卵泡素和促黄体素的分布特点

为了阐明妊娠期垂体中催乳素(PRL)、促卵泡素(FSH),促黄体素(LH)的分布和三者之间协调关系.本试验采用免疫组化SP法检测了PRL、FSH,LH三种激素在妊娠各期山羊的腺垂体细胞中免疫反应产物的分布特点.结果显示,在山羊妊娠过程中,腺垂体中PRL阳性细胞多存在于远侧部,数量逐渐增多,胞质呈强阳性;FSH和LH阳性细胞分布在远侧部和结节部,FSH胞质内颗粒着色深浅不一,LH多核膜着色;相对表达量都逐渐升高,而升高程度不同,表现为妊娠后期LH表达量急剧升高,FSH则变化较小,除了FSH的相对表达量在妊娠前期和中期之间无显著差异(P>0.05)外,3种激素的相对表达量在妊娠前期、中期和后期3个时期之间都存在显著差异(P<0.05),妊娠前、中期FSH的相对表达量均高于PRL和LH,妊娠后期LH的表达量最高.FSH次之,PRL最低.提示PRL,FSH和LH三种激素相互协同以促进胚胎着床并维持妊娠,而且在妊娠早期PRL起主要作用,之后协同FSH和LH维持妊娠.     

山羊GnRH和促性腺激素的释放特点

通过外科手术分别连续收集活体山羊中黄体期及早卵泡期的垂体门脉血样和外周血样,经放射免疫测定,山羊中黄体期和早卵泡期的促性腺激素释放激素（ＧｎＲＨ）、促黄体生成素（ＬＨ）和促卵泡素（ＦＳＨ）均呈波动式释放。在早卵泡期,ＦＳＨ单位时间内波动次数和血浆平均水平显著高于中黄体期;ＧｎＲＨ与ＬＨ的波动型基本一致,ＦＳＨ的变化不太规则。表明山羊垂体促性腺激素的释放受丘脑下部ＧｎＲＨ的调节,但ＦＳＨ似乎还存在其他调节机理。     

Use of a GnRH antagonist,antarelix, associated or not with hCG,to control ovulation in cyclic pony mares

The GnRH antagonist antarelix (Teverelix™) was administered to mares (0.01 mg/kg, i.v., twice a day) during the periovulatory period. In Experiment 1, 20 mares were divided into a treated (A3d−) and a control (Control−) group. A3d− mares received antarelix for 3 days from the day when the dominant follicle (F1) reached 32 mm (D0). In Experiment 2, 10 mares were divided into a treated (A6d+) and a control (Control+) group. A6d+ mares received antarelix for 6 days from D0 and hCG was injected in all animals (1600 IU, i.v.) on D1. Pregnancies were determined 13 days after ovulation. In both experiments, antarelix interrupted or totally abolished the LH surge. In Experiment 1, 5/10 of the A3d− mares (with maximum LH concentrations of 11.6 ng/ml at the beginning of treatment) ovulated at the same time as the Control− mares; the other five mares (with LH concentrations under 5.4 ng/ml) ovulated 13.4±0.6 days later. In Experiment 2, all the A6d+ mares ovulated at the same time as the Control+ mares. In treated mares which ovulated during the treatment, progesterone concentrations and fertility did not differ from control mares. These results demonstrate that in mares: (1) a small elevation of endogenous LH can induce ovulation, (2) ovulation can be postponed approximately 13 days after a 3-day antarelix treatment if initiated just before the preovulatory LH surge, (3) ovulation can be induced by hCG on depressed levels of endogenous LH, (4) the inhibition of the post ovulatory LH surge has no effect either on the corpus luteum or on fertility.     

Progesterone concentration,estradiol pretreatment,and dose of gonadotropin-releasing hormone affect gonadotropin-releasing hormone-mediated luteinizing hormone release in beef heifers

We examined whether progesterone (P₄)-induced suppression of LH release in cattle can be overcome by an increased dose of exogenous gonadotropin-releasing hormone (GnRH) or pretreatment with estradiol (E₂). In Experiment 1, postpubertal Angus-cross heifers (N = 32) had their 2 largest ovarian follicles ablated 5 d after ovulation. Concurrently, these heifers were all given a once-used, intravaginal P₄-releasing insert (CIDR), and they were randomly assigned to be given either prostaglandin F_2α (Low-P₄) or no treatment (High-P₄) at follicle ablation, and 12 h later. Six days after emergence of a new follicular wave, half of the heifers in each group (n = 8) were given either 100 or 200 μg of GnRH i.m. Plasma luteinizing hormone (LH) concentrations were higher in the Low- vs High-P₄ groups, and in heifers given 200 vs 100 μg of GnRH (mean ± SEM 15.4 ± 2.2 vs 9.1 ± 1.2, and 14.8 ± 2.1 vs 9.8 ± 1.4 ng/mL, respectively; P ≤ 0.01). Ovulation rate was higher (P = 0.002) in the Low-P₄ group (15/16) than in the High-P₄ group (6/16), but it was not affected by GnRH dose (P = 0.4). In Experiment 2, heifers (n = 22) were treated similarly, except that 5.5 d after wave emergence, half of the heifers in each group were further allocated to be given either 0.25 mg estradiol benzoate i.m. or no treatment, and 8 h later, all heifers were given 100 μg GnRH i.m. Both groups treated with E₂ (Low- and High-P₄) and the Low-P₄ group without E₂ had higher peak plasma LH concentrations compared to the group with high P₄ without E₂ (12.6 ± 1.8, 10.4 ± 1.8, 8.7 ± 1.3, and 3.9 ± 1.2 ng/mL, respectively; (P < 0.04)). However, E₂ pretreatment did not increase ovulation rates in response to GnRH (P = 0.6). In summary, the hypotheses that higher doses of GnRH will be more efficacious in inducing LH release and that exogenous E₂ will increase LH release following treatment with GnRH were supported, but neither significantly increased ovulation rate.     

Effects of GnRH treatment on initiation of pulses of LH,LH release,and subsequent concentrations of progesterone

Progesterone is essential for establishment and maintenance of pregnancy. One proposed method to increase progesterone is administering GnRH at insemination. However, this method has resulted in conflicting results. Therefore, 2 experiments were conducted to evaluate how administering GnRH at insemination affected pulses of luteinizing hormone (LH) and subsequent progesterone. In Experiment 1, cows were allotted to 2 treatments: (1) GnRH (100 μg) given approximately 12 h after initiation of estrus (n = 5); and (2) Control (n = 5). Blood samples were collected at 15-min intervals for 6 h at 12 (blood sampling period 1), 26 (blood sampling period 2), 40 (blood sampling period 3), 54 (blood sampling period 4), and 68 (blood sampling period 5) h after onset of estrus. Daily blood samples were collected for 17 d. In Experiment 2, cows were allotted into 2 treatments: GnRH administered 10 to 11 h (n = 10) or 14 to 15 h (n = 10) after onset of estrus. Daily blood samples were collected for 17 d. Cows treated with GnRH tended (P ≤ 0.075) to have greater LH release during blood sampling period 1, tended (P = 0.095) to have fewer pulses during blood sampling period 2, tended (P = 0.067) to have greater concentrations of progesterone, and had an earlier (P = 0.05) increase in progesterone than control cows. Cows treated with GnRH 10 to 11 h after onset of estrus had greater (P = 0.01) progesterone and an earlier (P = 0.04) increase in progesterone than cows treated 14 to 15 h. In conclusion, timing of GnRH treatment following onset of estrus influenced pulses of LH and subsequent progesterone.     

Effect of suppression of plasma prolactin on luteinizing hormone concentration, intersequence pause days and egg production in domestic hen

The aim of this study was to investigate the effects of suppression of plasma prolactin (PRL) concentration on circulating concentrations of luteinizing hormone (LH), progesterone (P(4)), estradiol (E(2)beta), pause days and egg production in birds later in the reproductive period. Twenty-four White Leghorn birds of same age group were divided into two groups of 12 in each. Birds of each group were administered s/c either with placebo (control group) or equal volumes of anti PRL agent (2-bromo-alpha-ergocriptine) solution containing at 100 microg/kg body weight/hen/week (treated group) from 72 to 82 weeks of age. Egg production and inter sequence pauses were recorded daily from both the groups. Plasma PRL, LH, E(2)beta and P(4) concentrations were estimated in blood samples collected at weekly intervals. At 77th weeks of age, blood samples from treated and control birds were obtained every 3h for 36h to study the surges of LH. It was found that plasma PRL concentration was lower (p<0.01) in bromocriptine treated birds with high concentrations of LH, its 3h LH surges, E(2)beta and P(4) in plasma. Higher egg production, less pause days in treated birds may be the result of low PRL concentration, associated with positively correlated responses of high concentrations of LH (with regular interval and duration of LH surges), E(2)beta and P(4) concentration required for completion of egg formation and oviposition. In conclusion, bromocriptine administration decreased (p<0.01) PRL concentration increased (p<0.01) steroid hormones and LH surges, for egg formation and oviposition and enabled the birds to lay more eggs even later in the productive period with the available resources under normal husbandry practices.