诱导鲢排卵时性类固醇激素含量的变化

本文报道了人绒毛膜促性腺激素(HCG)和哺乳动物促黄体激素释放激素类似物(LHRH—A)诱导鲢鱼排卵过程中,血清中性类固醇激素的变化规律。实验表明,经注射催产药物后,雌鱼血清中主要出现睾酮和17α20β-双羟孕酮(17α20βρ)浓度的变化,而雌二醇和孕酮浓度始终很低,变化不大。两种催产剂皆先诱导睾酮浓度达到峰值(4．83—16．65ng／ml),睾酮浓度随后下降,而17α20βρ浓度达到峰值(4．35—5．0ng／m1)时出现排卵。HCG和LHRH—A直接和间接地通过诱发17α20βρ的合成,再经其中介作用,最后诱导卵母细胞成熟排卵。雄鲢经人工催产注射后未发现17α20βρ的变化,睾酮反有所下降。本研究为采用17α20βρ作为鲢的催产药物提供了理论依据。     

壳聚糖-HCG缓释制剂对鱼类生殖内分泌机能的影响简

以壳聚糖为原料制备壳聚糖-HCG缓释制剂,进行激素埋植实验,间隔一定时间检测雌和雄鱼性腺发育、血清主要性激素含量和繁殖内分泌相关基因表达特征。结果表明:在埋植壳聚糖-HCG缓释激素后,雌鱼性成熟系数(GSI)、血清睾酮(T)水平、血清雌二醇(E2)水平在6—30d内较对照组效果明显;雄鱼GSI仅在第6天显著高于对照组,血清T水平在第2、第14天高于对照组。血清E2水平在实验期间与对照组无显著差异。RT-PCR结果显示:性腺型P450芳香化酶(CYP19A)在性腺中表达丰富,心脏中最少。雌鱼性腺P450芳香化酶(CYP19A)基因mRNA相对表达量在第2、第6天显著高于对照组,雄鱼在第6天显著高于对照,雌鱼性腺雌激素受体(ERα)基因mRNA相对表达量在14—30d显著高于对照组,雄鱼在第6至第21天显著高于对照组。研究表明,壳聚糖-HCG缓释制剂一次埋植后可在21d内稳定持久地释放激素,对调节鱼类的生殖机能具有良好的促进效果。     

恒河猴(Macaca mulatta)生殖周期内性类固醇激素分泌规律的研究

本文用放射免疫测定法对7只雌性恒河猴(Macaca mulatta)的20个月经周期进行了雌二醇,孕酮和睾酮的动态测定分析,其中15个月经周期的中期都有睾酮和雌二酮峰(其峰值分别为1010.7±0.65ng/ml. 正常黄体期的血清孕酮水平不低于1ng/ml. 20个月经周期的平均天数为28.6±5.4天, 滤泡期和黄体期分别为11.9±2.6和19.2±6.3天. 月经周期可用公式Y=18.92±0.03×X²(Y:月经周期,X: 黄体期. R=0.9444)表示.实验结果表明, 测定周期内三种性类固醇激素可以准确确定排卵.睾酮在生殖受气内的分泌调节机制还待进一步研究.     

壳聚糖-HCG缓释制剂对鱼类生殖内分泌机能的影响

以壳聚糖为原料制备壳聚糖-HCG缓释制剂,进行激素埋植实验,间隔一定时间检测雌和雄鱼性腺发育、血清主要性激素含量和繁殖内分泌相关基因表达特征。结果表明:在埋植壳聚糖-HCG缓释激素后,雌鱼性成熟系数（GSI）、血清睾酮（T）水平、血清雌二醇（E2）水平在630d内较对照组效果明显;雄鱼GSI仅在第6天显著高于对照组,血清T水平在第2、第14天高于对照组。血清E2水平在实验期间与对照组无显著差异。RT-PCR结果显示:性腺型P450芳香化酶（CYP19A）在性腺中表达丰富,心脏中最少。雌鱼性腺P450芳香化酶（CYP19A）基因mRNA相对表达量在第2、第6天显著高于对照组,雄鱼在第6天显著高于对照,雌鱼性腺雌激素受体（ER）基因mRNA相对表达量在1430d显著高于对照组,雄鱼在第6至第21天显著高于对照组。研究表明,壳聚糖-HCG缓释制剂一次埋植后可在21d内稳定持久地释放激素,对调节鱼类的生殖机能具有良好的促进效果。       

大白鼠早孕子宫细胞核雌二醇、孕酮受体水平的变化

本工作应用氚标记配基交换法测定了早孕大鼠子宫细胞核雌二醇与孕酮-受体复合物水平,同时也观察了外周血浆这两种甾体激素浓度的变化。实验结果表明,早孕期间子宫细胞核中雌二醇和孕酮受体水平发生了显著的改变,分别在受孕第3天和第4天出现雌二醇和孕酮受体高峰(均为～20,000结合位点/细胞);同时也分别在这两天观测到血浆雌二醇和孕酮浓度高峰(0.08毫微克/毫升和29毫微克/毫升)。我们得出的结论与其他研究工作者报道的一致,即血循环中卵巢甾体激素水平的升高导致子宫细胞核大量集聚激素-受体复合物,从而加速基因表达,刺激子宫的生长和细胞分化,为胚泡的着床造成适当的子宫环境。     

恒河猴(Macaca mulatta)生殖周期内性类固醇激素分泌规律的研究

本文用放射免疫测定法对7只雌性恒河猴(Macaca mulatta)的20个月经周期进行了雌二醇、孕酮和睾酮的动态测定分析,其中15个月经周期的中期都有睾酮和雌二醇峰(其峰值分别为1010.7±411.3pg/ml和179.1±91.3pg/ml),孕酮在黄体期的峰值为2.54±0.65ng/ml。正常黄体期的血清孕酮水平不低于1ng/ml。20个月经周期的平均天数为28.6±5.4天,滤泡期和黄体期分别为11.9±2,6和19.2±6.3天。月经周期可用公式Y=18.92±0.03×X~2 (Y:月经周期,X:黄体期。R=0.9444)表示。实验结果表明,测定周期内三种性类固醇激素可以准确确定排卵。睾酮在生殖周期内的分泌调节机制还待进一步研究。     

大阪鲫鱼（Carassius Auratus cuvieri Temminck et．Schlegel）雌性特异血清蛋白生化特性及免疫细胞化学定位的研究

雌性特异血清蛋白存在于成熟雌性大阪鲫鱼血清中,雄鱼则无。注射雌二醇可诱导雄鱼及成熟雌鱼合成这种蛋白质并引起鱼肝细胞粗面内质网增加,糖元颗粒减少。从诱导的大阪鲫鱼血清中分离出电泳纯的雌性特异血清蛋白的分子量为４６６０００±４０００（ｎ＝１０）,电泳谱带有３条,用纯的雌性特异血海蛋白制备的兔抗鱼抗血清不与雄鱼血清发生免疫反应,而与正常成熟雌鱼及诱导鱼的血清形成１条免疫沉淀线。免疫细胞化学定位诱导及成熟雌鱼的肝细胞核外细胞质有阳性颗粒,在卵母细胞外围有成团的阳性颗粒分布。     

鳗鲡繁殖生物学研究Ⅴ．性类固醇激素诱导雌鳗促性腺激素(GtH)分泌和卵巢发育的作用

多次注射雌二醇或睾酮对雌鳗促性腺激素(GtH)的合成与分泌活动以及卵巢发育都有明显的促进作用,其中睾酮的作用更较雌二醇显着;多次注射LHRH-A的促进作用则不明显.多次埋植雌二醇或睾酮都能促使脑垂体合成GtH,但所取血清样品中的GtH含量都未见明显增加;多次埋植雌二醇后血清中卵黄蛋白原的含量明显增加,但卵巢GSI增长幅度小,表明埋植雌二醇虽能促使肝细胞合成卵黄蛋白原并释放到血液中,但未能全部渗入卵母细胞内;多次埋植睾酮后血清中的卵黄蛋白原含量虽未见明显增加,但卵巢明显发育长大,这表明埋植睾酮能促使肝细胞合成的卵黄蛋白原迅速地通过血液运送到卵巢,并渗入卵母细胞内.       

催产时黄鳝性类固醇激素含量变化的研究

本文首次报道哺乳动物促黄体生成素释放激素类似物（ＬＨＲＨ－Ａ）诱导黄鳝排卵过程中,血浆雌二醇（Ｅ２）、孕酮（Ｐ）和睾酮（Ｔ）含量变化的规律。根据１７２尾黄鳝血样放射免疫测定结果,试验组雌鱼于排卵前相继出现Ｅ２和Ｐ浓度高峰（Ｐ〈０．０１）;雄鱼于催产后２４ｈ出现Ｔ浓度峰值（Ｐ〈０．０１）;试验组雌鱼的Ｔ含量与对照组无显著差异（Ｐ〉０．０５）。在对照组,雄鱼的Ｅ２和Ｐ浓度及雄鱼的Ｔ含量差异不显著（Ｐ〉     

圈养林麝社会等级与粪样类固醇激素水平的关系

动物社群的社会等级可对个体的资源分配、社群稳定及个体的行为对策产生重要影响,圈养动物的类固醇激素水平与饲养管理有关,可反映动物的社群紧张水平。深入理解圈养动物的社会等级与其类固醇激素水平的关系是进行濒危动物迁地保育和成功驯养的基础。2018年6月15日—8月15日,用焦点取样法对四川马尔康林麝繁育场的25头林麝进行了冲突行为取样及社会等级计算,采用放射免疫分析法检测了同期粪样的类固醇激素水平,分析了林麝社会等级与粪样皮质醇、睾酮及雌二醇水平的关系。结果表明:低等级雌麝的雌二醇水平(289.037±59.710 pg·g^-1,n=11)显著高于高等级雌麝(45.670±27.283pg·g^-1,n=6)(P<0.05),低等级雄麝的睾酮水平(3.863±1.538 ng·g^-1,n=3)和高等级雄麝(8.017±1.295 ng·g^-1,n=5)无显著差异(P>0.05);低等级雄麝(37.891±7.564 ng·g^-1,n=3)和雌麝(37.262±1.544 ng·g^-1,n=11)的皮质醇水平与高等级雄麝(29.947±2.441 ng·g^-1,n=5)及雌麝(37.478±4.628 ng·g^-1,n=6)间的差异不显著(P>0.05)。不区分性别,低等级林麝的皮质醇水平(37.397±1.826 ng·g^-1,n=14)和高等级个体(34.055±2.886ng·g^-1,n=11)间无显著差异(P>0.05)。研究结果表明,圈养林麝雌体的社会等级与其粪样雌二醇水平呈负相关,低等级雌麝的粪样雌二醇水平显著高于高等级雌麝。在麝类驯养实践中,可监测雌麝的社会等级和粪样雌二醇水平变化,预测雌麝的行为健康及繁殖成效。     

Bioactivity of stored luteinizing hormone-releasing hormone analogue (LHRHa) in sea bass, Lates calcarifer Bloch

The spawning induction activity of dissolved and pelleted (D-Ala⁶, Pro⁹ N ethylamide) luteinizing hormone-releasing hormone analogue (LHRHa) stored for various periods was assessed in mature female sea bass. The spawning response of mature fish was reduced significantly after injection of dissolved LHRHa (20 μg kg⁻¹) stored for more than 90 days in a refrigerator (4–10°C) or for more than 30 days at room temperature (28–30°C). Similar to fish administered fresh preparations of LHRHa, fish spawned successfully after injection of a solution of LHRHa previously frozen, subjected to alternate freezing and thawing, exposed to sunlight or implanted pelleted LHRHa (50 ng kg⁻¹) stored at room temperature for 30–120 days. Loss of hormone bioactivity after prolonged storage may have been due to bacterial growth in solubilized preparations. Injection or implantation of stored LHRHa did not influence egg production among treated sea bass. These results demonstrated the relatively prolonged shelf life of stored LHRHa.     

Melanin concentrating hormone (MCH) in the cerebrospinal fluid of ewes during spontaneous oestrous cycles and ram effect induced follicular phases

The melanin-concentrating hormone (MCH) is a neuropeptide synthesized by neurons of the lateral hypothalamus and incerto-hypothalamic area that project throughout the central nervous system. The aims of the present report were: (1) to determine if MCH levels in cerebrospinal fluid (CSF) of ewes vary between the mid-luteal and the oestrous phase of spontaneous oestrous cycles; and (2) to study if MCH levels in CSF of ewes vary acutely during the follicular phase induced with the ram effect in anoestrous ewes. In the first experiment, CSF was collected from 8 adult ewes during spontaneous oestrous and during the mid-luteal phase (8-10 days after natural oestrus). In the second experiment, performed during the mid non-breeding season, a follicular phase was induced with the ram effect. After isolating a group of 16 ewes from rams, CSF was obtained from 5 of such ewes (control group). Three rams were joined with the ewes, and samples were obtained 12h (n=6) and 24h (n=5) later. In Experiment 1, there were no differences in MCH concentrations in CSF measured during the mid-luteal phase and spontaneous oestrus (0.14 ± 0.04 vs. 0.16 ± 0.05 ng/mL respectively). In Experiment 2, MCH concentrations tended to increase 12h after rams introduction (0.15 ± 0.08 vs. 0.35 ± 0.21 ng/mL, P=0.08), and increased significantly 24h after rams introduction (0.37 ± 0.15 ng/mL, P=0.02). We concluded that MCH concentration measured in the CSF from ewes increased markedly during the response to the ram effect but not during the natural oestrous cycle of ewes.     

Spawning response of mature female sea bass,Lates calcarifer (Bloch), to a single injection of luteinizing hormone-releasing hormone analogue: effect of dose and initial oocyte size1

The effect of various doses of luteinizing hormone-releasing hormone analogue (LHRHa) ranging from 1 to 100 μg/kg body weight on the spawning response of mature female sea bass, Lates calcarifer (Bloch) was tested. A single intramuscular injection of LHRHa resulted in a dose-related increase in the spawning rate (number of spawnings of each fish over four consecutive days) of mature fish. An LHRHa dose of 5 μg/kg and less induced low spawning rates of 16.7% to 37.5% or at least one spawning every four days. However, mature sea bass spawned more than once (43.8–58.3%) in four days at dose levels of 10 μg/kg and above. Hormone treatment within the dose range tested did not influence the number, fertilization and hatching rates of spawned eggs. The influence of initial oocyte size on the LHRHa-induced spawning response of mature sea bass was also examined. Sea bass with an initial oocyte diameter of 0.30–0.39 mm did not respond to the single injection of 100 μg LHRHa/kg. In contrast, LHRHa induced spawning among sea bass with an initial egg size of 0.40–0.49 mm, although two of four sea bass of the same stage of ovarian maturity spawned spontaneously. Fish having an initial oocyte size of 0.50–0.55 mm spawned with and without LHRHa treatment. Spontaneous spawning among saline-injected sea bass occurred at a later time (24–58 h post-injection) compared to fish induced to spawn by a single injection of LHRHa (8–36 h post-injection). The initial spawning response time interval for fish with an initial egg size of 0.50 mm or greater was further reduced to 8–9 h by LHRHa. These results indicate that LHRHa can successfully induce spawning in mature female sea bass which have attained a critical oocyte diameter and that the spawning response interval is reduced with a further increase in egg size beyond the critical oocyte diameter limit.     

Serum T(4) and serum T(3) concentrations in immature captive whitetip reef sharks, Triaenodon obesus.

Serum T(3) (3,5,3' triiodothyronine) and serum T(4) (thyroxine) concentrations were repetitively assayed by radioimmunoassay over a three-year period in two male and two female immature captive whitetip reef sharks, Triaenodon obesus. These sharks were maintained at the Waikiki Aquarium, Honolulu, Hawaii, in an open system holding pool receiving 568 liters per minute of water from a saltwater well with an iodide concentration of 0.076 mg/liter. No significant male-female difference was observed for either serum T(3) or serum T(4). No seasonal pattern of serum T(3) was detected (P = 0.07). Serum T(3) concentrations ranged (mean +/- SEM) from 0. 52 to 0.83 ng/mL (0.67 +/- 0.01; n = 64). A significant seasonal difference was observed for serum T(4) (P < 0.001). Serum T(4) concentration was higher in winter (October-January) with a mean (range +/- SEM) of 6.58 ng/mL (1.48-8.77 +/- 0.35; n = 24) and lower in summer (May-August) with a mean of 3.62 ng/mL (1.34-5.71 +/- 0. 22; n = 24). The thyroid hormone T(4) has a seasonal rhythm even in immature sharks and may have an important role in physiology. J. Exp. Zool. 284:500-504, 1999.     

Effect of fasting on nychthemeral concentrations of plasma growth hormone (GH), insulin-like growth factor I (IGF-I), and cortisol in channel catfish (Ictalurus punctatus)

This experiment was conducted to characterize the effect of fasting versus satiety feeding on plasma concentrations of GH, IGF-I, and cortisol over a nychthemeron. Channel catfish fingerlings were acclimated for two weeks under a 12L:12D photoperiod, then fed or fasted for 21 d. On day 21, blood samples were collected every 2 h for 24 h. Weight of fed fish increased an average of 66.2% and fasted fish lost 21.7% of body weight on average. Average nychthemeral concentrations of plasma GH were not significantly different between fed (24.7 ng/mL) and fasted (26.8 ng/mL) fish, but average nychthemeral IGF-I concentrations were higher in fed (23.4 ng/mL) versus fasted (17.8 ng/mL) fish. An increase in plasma IGF-I concentrations was observed in fasted fish 2 h after a peak in plasma GH, but not in fed fish. Average nychthemeral plasma cortisol concentrations were higher in fed (14.5 ng/mL) versus fasted (11.0 ng/mL) fish after 21 d. Significant fluctuations and a postprandial increase in plasma cortisol were observed in fed fish and there was an overall increase in plasma cortisol of both fasted and fed fish during the scotophase. The present experiment indicates little or no effect of 21-d fasting on plasma GH levels but demonstrates fasting-induced suppression of plasma IGF-I and cortisol levels in channel catfish.     

泥鳅雄核发育纯合二倍体的产生

以机械方法挑去泥鳅(Misgurnus anguillicaudatus)×大鳞副泥鳅(Paramisgurnus dabryanus)(♀)属间杂交受精卵的雌核,得到泥鳅雄核发育单倍体胚胎。将这种单倍体胚胎的囊胚细胞核移植到大鳞副泥鳅去核卵中,获得了243个原肠胚胎,其染色体鉴定表明,29.6%的核移植体的染色体发生了加倍。在另一实验组中,从769个核移植卵得到了5尾2cm以上的个体。尾鳍染色体鉴定、肌肉LDH同工酶电泳和形态鉴别表明,这5尾核移植体为泥鳅雄核发育纯合二倍体。     

Estradiol and testosterone concentrations increase with fasting in weaned pups of the northern elephant seal (Mirounga angustirostris)

Although neonatal development is generally associated with increased levels of circulating testosterone (T) and estradiol (E2), food deprivation may inhibit steroidogenesis. Therefore, these potentially conflicting stimuli were examined in fasting weaned northern elephant seal (Mirounga angustirostris) pups by measuring serum concentrations of T, E2, progesterone (P4), and luteinizing hormone (LH) by either radioimmunoassay (P4, LH) or enzymeimmunoassay (T, E2). Blood samples were obtained from 20 male and 20 female pups at both early (<1 wk postweaning) and late (6-8 wk postweaning) periods during their natural postweaning fast. T in males (early: 2.9 +/- 0.4 ng/mL; late: 16 +/- 2 ng/mL; P < 0.0001) and E2 in females (early: 42 +/- 6 pg/mL; late: 67 +/- 5 pg/mL; P < 0.01) increased between the two measurement periods, while P4 (early: 2.5 +/- 0.3 ng/mL; late: 2.1 +/- 0.3 ng/mL; P > 0.05) did not. LH increased (early: 46 +/- 4 pg/mL; late: 65 +/- 6 pg/mL; P < 0.05) in males but not in females (early: 69 +/- 9 pg/mL; late: 65 +/- 6 pg/mL; P > 0.05). Increases in LH and T suggest that LH may stimulate T secretion. Alternatively, relatively low concentrations of LH in both males and females may reflect negative feedback inhibition imposed by elevated T and E2 concentrations. Despite the inherent postweaning fast, concentrations of T and E2 increased, suggesting that they may be critical for the continued development of pups. Therefore, compensatory mechanisms may exist that alleviate the fasting-induced inhibition of gonadal steroidogenesis during neonatal development in elephant seal pups.     

Pattern of sea bass oocyte development after ovarian stimulation by LHRHa

The cyclic pattern of oocyte development in the sea bass, Dicentrarchus labrax L., was studied after induction of spawning by two injections, 24 h apart, of a luteinizing hormone releasing-hormone analog (LHRHa) administered at the end of vitellogenesis. The first difference in the developmental stage of the ovary and in the size-frequency distribution of oocytes between the LHRHa treated group and the control group, was detected 32 h after the first injection, the LHRHa group showing a higher proportion of the 900 μm diameter oocyte class (maturing oocytes) ( P <0.01). At 48 h LHRHa-treated females showed an increase in the 1000 and 1100 μm classes (maturing oocyte and ovulated eggs) ( P <0.01) and at 72 h these females exhibited a bimodal pattern, reaching the highest proportions in the 1100 (27.4%) and the 600 (14.7%) μm classes (ovulated eggs and advanced vitellogenic oocytes, respectively). Bimodal distributions were present in 80% of the LHRHa-treated females. Once oocyte final maturation was triggered by LHRHa the time needed for ovulation was about 48 h and the interval between consecutive ovulations and spawnings seemed to be 48–72 h.     

The response to capture and confinement stress of plasma cortisol, plasma sex steroids and vitellogenic oocytes in the marine teleost, red gurnard

Reproductively active female red gurnard Chelidonichthys kumu were captured on long-lines, and placed in confinement tanks for 24, 48, 72 and 96 h to examine the effect of capture and confinement on reproductive parameters (experiment I). Plasma cortisol at the time of capture was elevated to levels typical of stressed fish in other species (53–125 ng ml⁻¹). Final plasma cortisol levels in red gurnard confined for any length of time were not significantly different from one another (ranging from 17 to 43 ng ml⁻¹), indicating that fish were chronically stressed when held in captivity for up to 96 h after capture. When initial and final plasma cortisol levels were compared within confinement groups, cortisol decreased significantly after 24 and 96 h of confinement indicating that some acclimation to captivity may have occurred. In contrast, plasma 17β-estradiol (E₂) and testosterone (T) levels decreased significantly to levels comparable to those in post-spawned fish, after any period of confinement, and remained low throughout the experiment. Another group of fish was captured and confined in the same manner as experiment I but subjected to repeated blood sampling every 24 h, until 96 h post-capture. In these fish, plasma cortisol levels decreased significantly from 127 ng ml⁻¹ after 24 h confinement and thereafter showed no change (25–45 ng ml⁻¹). Plasma E₂ decreased significantly after 72 h of confinement while plasma T showed no change from levels at capture. Increased amounts of follicular atresia were found in vitellogenic oocytes of fish confined for longer periods of time in experiment I, indicating that capture and confinement stress affect reproduction negatively in captive wild fish.     

Annual sex steroid and other physiological profiles of Pacific lampreys (Entosphenus tridentatus)

We documented changes in plasma levels of estradiol 17-β (E2), progesterone (P), 15α-hydroxytestosterone (15α-T), thyroxine (T4), triiodothyronine (T3), protein, triglycerides (TGs), and glucose in adult Pacific lampreys (Entosphenus tridentatus) held in the laboratory in two different years. Levels of E2 in both sexes ranged from 0.5 to 2 ng/mL from September to March, peaked in late April (2–4 ng/mL), and decreased in May, with levels higher in males than in females. Levels of P were low from September through April, but then increased substantially during May (2–4 ng/mL), with levels again highest in males. Levels of 15α-T in males were around 0.75 ng/mL through the winter before exceeding 1 ng/mL in April and decreasing thereafter, whereas females showed a gradual increase from 0.25 ng/mL in November to 0.5 ng/mL in April before decreasing. Thyroxine concentrations differed between fish in each year, with most having levels ranging from 0.75 to 2.5 ng/mL in the fall and winter, and only fish in 2003 showing distinct peaks (3–4 ng/mL) in early April or May. Plasma T3 was undetectable from November through mid-March before surging dramatically in April (ca. 150 ng/mL) and decreasing thereafter. Levels of protein, TGs, and glucose decreased or were stable during the fall and winter with TGs and glucose surging in late April to early May for some fish. Our study is the first to document long-term physiological changes in Pacific lampreys during overwintering and sexual maturation and increases our understanding of the life history of this unique fish.