雌激素对青春期前雌性大鼠下丘脑促性腺激素释放激素表达和分泌的影响

目的观察外源性雌激素[17β-雌二醇(E2)]对大鼠青春期发育和下丘脑促性腺激素释放激素(GnRH)合成和分泌的影响。方法将50只SD大鼠分为短期对照组、短期E2组、长期对照组、长期E2组和自然发育组。除自然发育组大鼠外,其余各组大鼠均于15日龄皮下注射药物,短期E2组和长期E2组大鼠注射雌激素,相应对照组大鼠注射溶媒麻油,均1次.d-1。其中短期E2组、短期对照组连续注射5d,长期E2组、长期对照组连续注射13d。检查阴道开口(VO)情况,酶联免疫吸附法(ELISA)检测氯化钾(KCl)刺激前后下丘脑培养液中GnRH水平的变化,荧光实时定量PCR分析下丘脑GnRHmRNA的表达。结果各E2注射组大鼠VO时间较自然发育组提前(P<0.05);下丘脑组织培养液KCl刺激前,自然发育组GnRH分泌量较其余各组分泌量多(P<0.05);刺激后,各组GnRH分泌量升高,短期对照组GnRH分泌量显著少于短期E2组和自然发育组(P<0.05);自然发育组下丘脑GnRHmRNA的表达显著升高(P<0.05)。结论雌激素可通过刺激雌性大鼠下丘脑GnRH分泌,提前启动下丘脑-垂体-性腺轴功能,从而影响青春期发育。     

促性腺激素释放激素受体的研究进展

促性腺激素释放激素（GnRH）受体是G蛋白偶联受体家族中的一员,是介导GnRH生理功能所必需的。该受体在体内分布广泛,除位于下丘脑－垂体－性腺轴外,在胃肠道、某些肿瘤细胞及外周血单核细胞中也有表达,其表达水平可受GnRH自身、性甾体激素及激活素等神经内分泌激素的调控。     

兴奋性氨基酸受体激动剂诱导雌性大鼠青春期发生的实验研究

目的　研究兴奋性氨基酸受体激动剂对雌性大鼠青春期启动的影响。方法　 2 6日龄雌性大鼠 36只随机分为 3组 ,实验组每日皮下注射N 甲基 DL 天冬氨酸 (NMA) ,同龄青春前期大鼠 (对照 1组 )和正常青春发育大鼠 (对照 2组 ) :皮下注射生理盐水。于第一个发情前期日将大鼠处死 ,并检测其下丘脑 垂体 性腺轴启动指标。结果　实验组大鼠阴道口开放和首次发情间期较对照 2组明显提前 (33.18± 3.31dvs 39.4 7± 5 .2 4d ;36 .0 5± 3.4 3dvs 4 1.6 7± 4 .96d ,P均 <0 .0 5 ) ;两组阴道口开放后均出现规则性周期 ;对照 1组大鼠处死时阴道口尚未开放。实验组卵巢、子宫指数、卵巢黄体出现率、子宫壁厚度、血黄体生成素 (LH)和下丘脑促性腺激素释放激素 (GnRH)mRNA表达水平与对照 2组均无明显差异 (P均 >0 .0 5 ) ,与对照 1组均有明显差异 (P均 <0 .0 5 )。结论　NMA可作用于下丘脑 ,使雌性大鼠提前进入青春期 ,并表现出与正常进入青春期大鼠相同的性发育特征     

促性腺激素释放激素受体的研究进展

促性腺激素释放激素（ＧｎＲＨ）受体是Ｇ蛋白偶联受体家族中的一员,是介导ＧｎＲＨ生理功能所必需的。该受体在体内分布广泛,除位于下丘脑－垂体－性腺轴外,在胃肠道、某些肿瘤细胞及外周血单核细胞中也有表达,其表达水平可受ＧｎＲＨ自身、性甾体激素及激活素等神经内分泌激素的调控。     

GnIH/GPR147和Kisspeptin/GPR54与青春发育启动

小儿青春发育启动与下丘脑-垂体-性腺轴的发动有关,而下丘脑促性腺激素释放激素（ gonadotropin-releasing hormone,GnRH）神经元的激活是青春期启动的关键。青春期启动过程是一个复杂的过程,GnRH又受到许多相关神经肽调节的影响。近来研究发现促性腺激素抑制激素（ gonadotropin-inhibitory hormone,GnIH）和 Kisspeptin 分别能够抑制和促进哺乳类动物的下丘脑 GnRH 的分泌,提示 GnIH 和Kisspeptin对生殖内分泌轴起着非常重要的调节作用。因此,GnIH/GPR147和Kisspeptin/GPR54两条通路可能与小儿青春发育启动密切相关。     

转化生长因子和性早熟

转化生长因子（ＴＧＦ）是一种具有广泛生物效应的多肽类物质,按分子组成、膜受体结构及生物学效应的不同,分为ＴＧＦ－α、ＴＧＦ－β二类。正常的青春发育受下丘脑－垂体－性腺轴的控制。此轴功能的提前发动、亢进导致真性性早熟。下丘脑的神经分泌受多种因素的调节,目前认为ＴＧＦ也参与中枢神经内分泌的调节,它的分泌异常可能与性早熟发病机制有关。     

性早熟雌性大鼠下丘脑促性腺激素释放激素分泌及KiSS-1基因、雌激素受体α基因的表达

目的 观察外源性雌激素(苯甲酸雌二醇,EB)、特异性雌激素α受体(ERα)激动剂(PPT)、特异性雌激素β受体激动剂(DPN)对青春期发育大鼠下丘脑KiSS-1、ERα基因表达的影响.方法 将40只SD大鼠随机分为4组:EB组、PPT组、DPN组、自然发育组,于日龄16 ～20 d连续5d,EB组、PPT组、DPN组分别注射对应的药物,自然发育组只观察不干预,检查大鼠阴道开口(VO)情况,于VO2 d后处死,实时荧光定量PCR检测其下丘脑KiSS-1及ERαmRNA的表达,ELISA检测氯化钾(KCI)刺激前后下丘脑培养液促性腺激素释放激素(GnRH)的分泌量.结果 各干预组大鼠VO时间均较自然发育组提前[(22.4±1.2)d、(22.8±1.1)d、(27.5±2.3) dvs(31.8±0.8)d,P＜0.01];自然发育组KiSS-1 mRNA及ERα mRNA的表达较各干预组均显著增高[KiSS-1 mRNA:(3.95±1.84) vs (0.66±0.39)、(2.08±0.37)、(1.43±0.33),P＜0.01;ERα mRNA:(5.51±1.86) vs (0.74±0.46)、(3.85±1.67)、(2.98±1.43),P＜0.01];KCI刺激前DPN组较EB组、PPT组及自然发育组下丘脑培养液GnRH分泌量明显减少[(39.91±4.83) ng·L-1vs(45.11±7.01)ng·L-1、(49.17±5.01) ng·L-1、(47.82±7.51) ng·L-1,P＜0.05],KC1刺激后各组下丘脑培养液GnRH分泌量均明显增加,各组间无明显差异[(239.47±55.87) ng·L-1、(211.24±38.54) ng·L-1、(208.17 ±55.33) ng·L-1、(226.58±49.73)ng·L-1,P＞0.05].结论 EB、PPT及DPN均可以促进大鼠下丘脑GnRH分泌,进而启动下丘脑-垂体-性腺轴,使性发育提前.雌激素诱导的大鼠性早熟机制可能与雌激素的非经典非基因作用机制相关.     

下丘脑Kisspeptin表达与青春期发育的关系

青春期启动始于下丘脑促性腺激素释放激素(GnRH)分泌的提高.Kisspeptin/G蛋白耦联受体(GPR 54或KISSIR)信号通路是最近发现能促进GnRH分泌和正常青春期启动的关键因素.KISS1表达定位于下丘脑的特定区域,在动情周期中受性激素调节,Kisspeptin传递性激素的反馈信号至GnRH细胞,特别是正反馈信号可以引起排卵前的GnRH/黄体生成素分泌.Kisspetin与位于下丘脑GnRH神经元上的受体KISS1R相互作用,导致GnRH脉冲性释放和青春期启动.     

Kiss-1在雌性性早熟大鼠下丘脑中mRNA的表达

目的：探讨Kiss-1在雌性性早熟大鼠不同时期下丘脑中mRNA的表达。方法：正常5日龄清洁级Sprague-Dawley雌性大鼠40只,随机分为4组,对照1组 （正常青春前期）,对照2组（正常青春期早期）,模型1组（青春期早期）,模型2组（青春期中期）,每组10只,达那唑300 μg皮下注射以诱导真性性早熟。半定量RT PCR法检测对照1组,对照2组,模型1组,模型2组的Kiss-1 mRNA的表达。结果：与对照1组相比,模型1组和模型2组下丘脑Kiss-1 mRNA水平分别增加了1.4和2.8倍,差异具有显著性（P<0.05）。模型2组大鼠下丘脑Kiss-1 mRNA表达水平高于模型1组,差异有显著性（P<0.05）。 对照2组与模型1组的Kiss-1 mRNA的表达差异无显著性（P>0.05）。结论：Kiss-1 mRNA的表达与生长发育的时期密切相关,提示Kiss-1 可能与真性性早熟的发生有关。［中国当代儿科杂志,2007,9（1）：59-62］     

神经介素U及其受体2在正常发育与性早熟雌性大鼠中枢神经系统中表达的变化及意义

目的研究神经介素U(NMU)及其受体2(NMUR2)在正常发育与性早熟雌性SD大鼠中枢神经系统中的表达,分析其在真性性早熟发生中可能的作用。方法正常5日龄SD雌性大鼠60只,随机分成6组:实验1组(性早熟青春期前组)、实验2组(性早熟青春期组)、实验3组(性早熟成年期组)和对照1组(正常青春期前组)、对照2组(正常青春期组)、对照3组(正常成年期组),每组10只。实验组一次性皮下注射达那唑300μg,建立性早熟模型。利用RT-PCR方法检测各组下丘脑NMUR2 mRNA及垂体NMU mRNA的表达水平。结果1.对照与实验1组NMU mRNA表达均显著高于实验2、3组和对照2、3组(Pa<0.01),而实验2与3组、对照2与3组表达均无显著性差异(Pa>0.05)。2.实验2组NMU mRNA表达明显低于对照1组(相同日龄)(P<0.01)。3.对照与实验2组NMU mRNA的表达无显著性差异(P>0.05)。4.NMUR2 mRNA的表达与NMU mRNA的表达呈现相同的变化趋势。结论NMU及其受体NMUR2可能在真性性早熟的发生中起重要作用。     

GnRHa激发试验对性早熟的诊断价值探讨

目的　探讨GnRH类似物 (GnRHa)曲普瑞林 (triptorelin)激发试验对于性早熟的诊断价值。方法　将因乳房发育提前而就诊的 95例女孩 (均于就诊时行 0、30和 6 0minGnRHa激发试验 )分为 3组 :真性性早熟(CPP)组 5 0例、单纯性乳房早发育 (PT)组 32例、外周性性早熟 (PPP)组 13例。以 33例健康的青春前期女孩作为对照。比较各组血清促卵泡激素 (FSH)、促黄体生成激素 (LH)激发值和基值、FSH和LH的最大反应 (ΔFSH和ΔLH)及峰值之比 (峰LH/FSH ,免疫化学发光法测定 )。绘制诊断CPP的受试者工作特性曲线 ,确定具有较高诊断灵敏度和特异度的峰LH和峰LH/FSH的截断值。结果　PPP、PT、CPP和对照组的FSH基值以及LH基值均有明显的重迭。PPP组 3个时相的血清FSH及LH浓度无差异。PT、CPP组 3个时相的血清FSH及LH浓度均有显著差异 (P =0 0 0 )。PT组ΔFSH (8 76± 3 74 )IU/L显著高于ΔLH(2 5 7± 1 5 6 )IU/L(P =0 0 0 )。CPP组ΔLH(2 3 2 3± 19 16 )IU/L显著高于ΔFSH(10 6 0± 4 79)IU/L(P =0 0 0 )。PT组和CPP组的ΔFSH无差异 ,CPP组ΔLH和峰LH/FSH(1 6 6± 1 2 6 )显著高于PT组 (0 2 8± 0 11) (P =0 0 0 )。以LH峰值≥5 0 5IU/L为前提 ,诊断CPP的灵敏度和特异度分别为 98 0 %和 90 6 %。结论　PPP组     

促性腺激素释放激素激动剂治疗女童性早熟的不良反应探析

促性腺激素释放激素激动剂(gonadotropin releasing hormone agonist,GnRHa)是目前临床广泛应用的相对安全的性早熟治疗药物.患儿在停药后可以正常月经来潮、怀孕、生育.GnRHa不会降低青春期后的子宫体积,停药后的黄体生成素、卵泡刺激素及性激素水平可恢复至接近或超过停药前水平.研究提示促性腺激素释放激素拟似物可能会增加罹患雄激素过多症及多囊卵巢综合征的风险,但尚缺乏较高等级的证据.现有的研究不能提供充分证据表明GnRHa对骨矿物质密度有显著和不可逆的负面影响.GnRHa可能具有增加体质量指数(BMI)的不良反应,亦有研究表明GnRHa有助于降低BMI,或不会增加BMI.     

Oral administration of arginine enhances the growth hormone response to growth hormone releasing hormone in short children

We have evaluated the effect of oral administration of arginine chlorhydrate on the growth hormone response to growth hormone releasing hormone in a group of nine short prepubertal children (six boys and four girls). Arginine chlorhydrate 10 g, administered orally 60 min before an iv bolus injection of growth hormone releasing hormone 1–29, 1 μg/kg, significantly enhanced the growth hormone response to the neuropeptidc, confirming the results of previous studies which used the iv route. Furthermore, our data strengthen the view that the effects of arginine chlorhydrate on growth hormone secretion are mediated by inhibition of endogenous somatostatin release.     

Oral administration of arginine enhances the growth hormone response to growth hormone releasing hormone in short children

We have evaluated the effect of oral administration of arginine chlorhydrate on the growth hormone response to growth hormone releasing hormone in a group of nine short prepubertal children (six boys and four girls). Arginine chlorhydrate 10 g, administered orally 60 min before an iv bolus injection of growth hormone releasing hormone 1–29, 1 μg/kg, significantly enhanced the growth hormone response to the neuropeptidc, confirming the results of previous studies which used the iv route. Furthermore, our data strengthen the view that the effects of arginine chlorhydrate on growth hormone secretion are mediated by inhibition of endogenous somatostatin release.     

Diagnostic value of growth hormone-releasing hormone test in children and adolescents with idiopathic growth hormone deficiency

Average growth hormone (GH) peaks following an i.v. growth hormone releasing hormone (GHRH) 1–29 stimulation test were significantly lower in 48 children and adolescents with GH deficiency (GHD) than in 20 age-matched controls (15.2+12.7 vs 37.5+28.1 ng/ml, 2P<0.001). Twelve patients exhibited a low GH peak (<5 ng/ml), 27 demonstrated a normal response (>10 ng/ml) and 9 showed an intermediate rise in plasma GH (5–10 ng/ml). Six of the 12 patients with low GH response to the first GHRH stimulation failed to respond to two other tests immediately before and after a 1 week priming with s.c. GHRH. These subjects with subnormal GH increase at repeat testing had total GHD (TGHD) and multiple pituitary hormone deficiency (MPHD) and had suffered from perinatal distress. On the contrary, 26 of 27 patients with normal GH response to the first test had isolated GHD and only a minority (8/27) had signs of perinatal distress. It is concluded that perinatal injuries primarily damage pituitary structures and that a pituitary defect more probably underlies more severe forms (TGHD and MPHD) of GHD.Presented in part at the 7th Meeting of the Italian Society for Paediatric Endocrinology (Milan, 20–21 October 1989)     

Effects of long-term growth hormone releasing hormone 1 -29 in significantly short children

Seven children with significant idiopathic short stature (SISS) whose heights were significantly below the third percentile (SD score for height —2.5 to —3.5) and who had normal levels of growth hormone (GH) were treated with growth hormone releasing hormone (GH-RH) in a dose of 30 /μg/kg/day. Therapy was discontinued if patients failed to increase their rates of growth by more than 2.0 cm/year over their pre-therapy growth rate. Treatment was discontinued in two of the patients after 12 months but was continued in the other five for 24 months. These data demonstrate that some patients with SISS grow well during the first 2 years of treatment with GH-RH.     

Effect of two consecutive administrations of GHRH in children with constitutional growth delay

It has been suggested that children with constitutional growth delay might have a transient immaturity of the neurotransmitter pathways necessary for the control of growth hormone releasing hormone (GHRH) secretion. In this study we evaluated the effects of two consecutive GHRH boluses (1 g/kg, i.v.) in nine prepubertal boys with constitutional growth delay. Growth hormone (GH) responses to GHRH administration were similar to that observed in normal children (first GHRH bolus, GH net incremental area under the curve (nAUC) ±SE: 788±244 vs 984±242 ng/ml per hour; second bolus, GHnAUC: 657±122 vs 541±129 ng/ml per hour, respectively). These data suggest that no relevant abnormalities in the mechanisms determining the somatotroph sensitivity to GHRH are present in children with constitutional growth delay.     

Comparison of growth hormone releasing hormone therapy and growth hormone therapy in growth hormone deficiency

Seven children with growth hormone deficiency of hypothalamic origin responded to an i.v. bolus of growth hormone releasing hormone (GHRH) (1–29)-NH2 with a mean serum increase of 10.7 ng/ml growth hormone (GH) (range 2.5–29.3 ng/ml). Continuous s.c. administration of GHRH of 4–6 g/kg twice daily for at least 6 months did not improve the growth rate in five of the patients. One patient increased his growth rate from 1.9 to 3.8 cm/year and another from 3.5 to 8.2 cm/year; however, the growth rate of the latter patient then decreased to 5.4 cm/year. When treatment was changed to recombinant human growth hormone (rhGH) in a dose of 2 U/m² daily, given s.c. at bedtime, the growth rate improved in all patients to a mean of 8.5 cm/year (range: 6.2 to 14.6). Presently GHRH cannot be recommended for the routine therapy of children with growth hormone deficiency since a single daily dose of rhGH produced catch-up growth which GHRH therapy did not.Abbreviations GH growth hormone - GHD growth hormone deficiency - GHRH growth hormone releasing hormone - hGH human growth hormone - rhGH recombinant human growth hormone - SM C/IGF I somatomedin C/insulin-like growth factor I On the occasion of the 85th birthday of Prof. Dr.Dr.h.c. mult. Adolf Butenandt     

Circulating immunoreactive growth hormone releasing hormone concentrations and growth hormone response to growth hormone releasing hormone in short children

To study the role of peripheral immunoreactive growth hormone releasing hormone (ir-GHRH) concentrations and the GHRH test in the evaluation of growth hormone (GH) secretion in short stature, 46 children with a mean age of 9.4 years (range 1.6–16.3 years) and a mean relative height score of –3.2 SD (range –5.0–2.1 SD) were investigated. The children were divided into prepubertal (n=35) and pubertal (n=11) and the prepubertal children further into three groups based on their maximal GH responses to insulin-induced hypoglycaemia (IIH) and clonidine: (1) GH deficient subjects (maximal GH<10 g/l in both test); (2) discordant responders (maximal GH<10 g/l in one test and 10 g/l in the other); and (3) normal responders (maximal GH10 g/l in both test). Peripheral ir-GHRH concentrations were measured during the IIH test by radioimmunoassay after purification of plasma samples on Sep-pak cartridges. Among the prepubertal children 10 fell into group 1, 16 into group 2 and 9 into group 3. Children in group 1 were older, than those in group 3. There were no significant differences in relative heights and weights or absolute and relative growth velocities between the groups. Subjects in groups 1 and 2 had lower maximal GH responses to GHRH than those in group 3. There were no significant differences in the basal plasma ir-GHRH concentrations between the groups. Nine children (19.6%) had somatotrophs with a poor response to a single dose of exogenous GHRH (maximal GH<10 g/l). These subjects had increased basal plasma ir-GHRH concentrations. All of them had a decreased GH response to IIH and/or clonidine. Pubertal children had higher circulating ir-GHRH levels than the prepubertal subjects. There was an inverse correlation (r=–0.46;P<0.001) between the maximal GH response to GHRH and calendar age in the whole series. These observations suggest that: (1) a substantial proportion of short children have a heterogenous GH response to pharmacological stimuli necessitating complementary evaluation of their spontaneous GH secretion; (2) a poor response to exogenous GHRH is associated with increased ir-GHRH levels in the peripheral circulation; (3) all children with normal GH responses in pharmacological tests respond normally to GHRH and (4) the pituitary sensitivity to GHRH decreases with increasing age. Peripheral ir-GHRH concentrations do not differentiate between short children with growth hormone deficiency (GHD) and those with undefined short stature. The GHRH test is of limited value in the diagnosis of GHD, since a normal GH response does not exclude GHD, although a subnormal response appears to reflect dysfunctional GH secretion.     

Early medical and surgical treatment of cryptorchidism: clinical,anatomic, and histologic findings

In 56 boys more than 6 month of age with cryptorchidism, luteinizing hormone releasing hormone (LHRH) was administered as a nasal spray 1.2 mg/day for 4 weeks. The nonresponders received human chorionic gonadotropin (HCG) 500 IU i.m. three times a week for 3 weeks. With the combined treatment, 46.5% of testes descended into the scrotum. Testicular descent occured more often in patients whose testes were located in a lower position. The initial position of the testes at clinical examination correlated significantly with the position at surgical inspection and the extent of epididymal malformation: the higher the clinical position of the testes, the more pronounced the maldescent and epididymal malformation. Histological findings indicated a paucity of germinal epithelium and atrophy of the Leydig cells. A significant inverse correlation existed between age at surgery and number of spermatogonia. Therefore, we advocate the earliest feasible treatment for cryptorchidism with a combination of LHRH and HCG, and for non-responders a surgical corrective procedure.