Suppression of ovulation in the rat by an orally active antagonist of luteinizing hormone-releasing hormone

A synthetic antagonist of luteinizing hormone-releasing hormone blocked ovulation in rats in a dose-dependent manner when given by gavage on the afternoon of proestrus. Ovulation was delayed for at least 1 day in all animals given 2 milligrams of antogonist and in some of the animals treated with 1 or 0.5 milligram. Oral administration of 2 milligrams also blocked the preovulatory surge of luteinizing hormone. This demonstration that antagonists of luteinizing hormone-releasing hormone can have oral antiovulatory activity clearly enhances their therapeutic potential.     

Follicle-stimulating hormone secretion in the female rat: cyclic release is dependent on circulating androgen

In adult cyclic female rats, intravenous injections of an antiserum to testosterone prevented the continued increase in serum follicle-stimulating hormone (FSH) which normally occurs during the early morning hours of estrus. This treatment did not prevent the initial increases in serum FSH (and luteinizing hormone) which occur during the critical period (1400 to 2000 of proestrus), nor did it interfere with subsequent ovulation. These observations indicate the existence of two separate mechanisms for preovulatory FSH release in the rat and implicate circulating testosterone as the stimulus for continued secretion of FSH during estrus.     

成年雌性比格犬发情期中生殖激素变化规律

研究成年雌性比格犬体内促黄体生成激素（LH）、雌二醇（E2）及孕酮（P）的分泌规律。采用放射免疫法测定母犬发情期内血清中LH、E2及P的含量。所有10只成年雌性比格犬LH浓度在发情前期开始后8～11d达到最高浓度7.41±0.48mU/mL。E2浓度在发情前期开始后的7～11d达到最高值80.64±5.73pg/mL,有8只成年雌性比格犬E2的峰值出现在LH峰值前24h,之后迅速下降,同时P浓度开始初次升高,并维持在这一浓度（14.16±2.52ng/mL）3～5d之后继续升高,P在LH峰值后的10～14d达到最高值36.19±2.04ng/mL。实验表明E2对LH峰值的出现具有负反馈调节作用,E2∶P浓度比的下降促使LH峰值出现。     

Polyamine metabolism: a potential therapeutic target in trypanosomes

alpha-Difluoromethylornithine (RMI 71,782), a specific irreversible inhibitor of the first step in polyamine biosynthesis, that is, the formation of putrescine from ornithine by ornithine decarboxylase, cures mice infected with a virulent, rodent-passaged strain of Trypanosoma brucei brucei. This parasite is closely related to the trypanosomes that cause human sleeping sickness. The drug, which is remarkably nontoxic, was effective when administered in drinking water or by intubation. The ability of the compound to inhibit ornithine decarboxylase in vitro was demonstrated by the reduced amounts of putrescine synthesized from tritiated ornithine in Trypanosoma brucei suspensions. These observations direct attention to polyamine metabolism as a target for chemotherapy of parasitic diseases.     

鸟氨酸脱羧酶抗酶基因功能的研究进展

鸟氨酸脱羧酶抗酶(OAZ)具有调控细胞多胺代谢、诱导细胞凋亡、抑制肿瘤细胞增殖的功能。近年来研究发现,鸟氨酸脱羧酶抗酶在动物繁殖过程中也具有重要调控作用。就鸟氨酸脱羧酶抗酶基因功能的研究现状做一综述,为进一步深入研究OAZ功能提供帮助。     

Growth factors modulate gonadotropin receptor induction in granulosa cell cultures

Epidermal growth factor and fibroblast growth factor inhibited follicle-stimulating hormone-dependent induction of luteinizing hormone receptor in cultured ovarian granulosa cells of the rat. In contrast, platelet-derived growth factor potentiated the induction of luteinizing hormone receptor by follicle-stimulating hormone. These results indicate that growth factors, well known for their effects on mitosis and DNA synthesis in cultured mammalian cells, are also able to modulate hormone-dependent differentiation in an endocrine target cell.     

Ornithine decarboxylase is important in intestinal mucosal maturation and recovery from injury in rats

A transient increase in ornithine decarboxylase activity and polyamine biosynthesis occurs in the intestinal mucosa of the newborn rat in the third week after birth. During this period, there is a rapid conversion of the mucosa from a fetal to a mature adult status. A similar increase in ornithine decarboxylase activity also accompanies the rapid recovery of the mucosa 1 week after an injury is induced by chemotherapy in adult rats. In vivo, alpha-difluoromethyl ornithine, a highly selective, enzyme-activated, irreversible inhibitor, suppresses these increases in mucosal ornithine decarboxylase and delays both intestinal mucosal maturation and recovery from injury. Thus increased ornithine decarboxylase activity, with the resultant increase in polyamine content, may play an essential role in intestinal mucosal maturation and regeneration in the rat.     

精准定时输精对后备母猪早期胚胎发育与繁殖性能的影响

为探讨精准定时输精(fixed-time artificial insemination,FTAI)对后备母猪早期胚胎发育和繁殖性能的影响,试验1选取自主培育的金乌猪后备母猪43头,随机分为2组,其中,对照组24头,为自然发情,观察后人工配种(artificial insemination,AI);试验组19头,为精准...     

Arginine decarboxylase and polyamines required for embryogenesis in the wild carrot

Embryogenic cultures of Daucus carota treated with 1 millimolar alpha-difluoromethylarginine, a specific inhibitor of arginine decarboxylase, exhibited nearly a 50 percent reduction in embryo formation compared with controls. Putrescine and spermidine concentrations in the treated cells were greatly reduced. Addition of putrescine, spermidine, or spermine to the culture medium restored embryogenesis in the treated cultures. Embryogenesis was not significantly affected by alpha-difluoromethylornithine, an inhibitor of ornithine decarboxylase. These results suggest that polyamines have a major function in plant embryo development and that the wild carrot synthesizes polyamines through the biosynthetic pathway involving arginine decarboxylase rather than ornithine decarboxylase.     

Ovulation in hamster: induction by subunit of ovine interstitial cell stimulating hormone

As little as 5 micrograms of interstitial cell stimulating hormone (ICSH) or 20 micrograms of ICSH-beta is effective for the induction of ovulation in 100 percent of hamsters treated at 0500 hours on day 4 after lordosis, whereas as much as 800 micrograms of ICSH-alpha is ineffective. Both ICSH and ICSH-beta are also effective for induction of ovulation in hypophysectomized animals. Thus, the ovulation-inducing activity of the ICSH molecule resides in its beta subunit.     

广西沼泽型母水牛发情淡季生殖激素的变化规律研究

[目的]研究发情淡季母水牛生殖激素的变化规律及各激素之间的相互关系。[方法]采用酶联免疫分析方法(ELISA)测定了发情淡季广西沼泽母水牛血样中促卵泡素(FSH)、促黄体素(LH)、抑制素(INH)、雌二醇(E2)和孕酮(P4)的浓度变化,并结合B超技术检测了母水牛卵泡在发情周期中的变化。[结果]广西沼泽型母水牛血样中E2和P4浓度呈波动式变化。其中,E2分别在排卵后第13天d下降到基础水平。FSH在排卵后的第10天出现峰值;LH在排卵前2天出现峰值;INH在排卵后第4天出现峰值。各种激素之间存在相关性。FSH、LH和INH三者两两之间存在极显著相关性,INH与E2、P4存在显著相关性,E2与P4存在极显著相关性。[结论]该研究可为指导适时配种、提高广西本地沼泽型母水牛的繁殖力提供理论参考。     

Progesterone administration in vivo stimulates release of luteinizing hormone-releasing hormone in vitro

The release of luteinizing hormone-releasing hormone (LHRH) from tissue from the mediobasal hypothalamic-anterior hypothalamic-preoptic area of prepuberal female rats was measured in a perfusion system. Measurements were also made of the concentrations of LHRH in these tissue fragments and of luteinizing hormone in serum obtained when the rats were killed. Four groups of immature rats were studied: intact, ovariectomized, ovariectomized and implanted with estradiol-containing capsules, and ovariectomized rats primed with estradiol and injected with progesterone. The release of LHRH from the tissue of ovariectomized animals was significantly less than that of intact females and was not modified when the ovariectomized rats received estradiol. However, there was a four- to fivefold increase in LHRH release from tissue of ovariectomized rats primed with estradiol when they were killed 6 hours after they received an injection of progesterone. The concentrations of LHRH in tissue and of luteinizing hormone in serum varied among groups and with the time of day that the animals were killed. The interactions among luteinizing hormone, gonadal steroids, and the photoperiod seem to set the appropriate conditions for neural processes triggering a complete and normal release of luteinizing hormone.     

多胺代谢相关基因在小鼠子宫内膜细胞中的调节

利用鸟氨酸脱羧酶(ODC)siRNA干涉、ODC过表达、添加特异性ODC抑制剂二氟甲基鸟氨酸(DFMO)处理小鼠子宫内膜上皮细胞和基质细胞,采用实时定量PCR对多胺代谢相关酶类mRNA水平进行检测。结果显示:在子宫内膜上皮和基质细胞中,ODC siRNA转染后可导致SSAT mRNA水平下降为对照组的71.78%和54.36%(P<0.01),SAMDC mRNA水平上升为对照组的1.666 6倍和3.036 6倍(P<0.01);ODC过表达造成SSAT水平为对照组的1.921 4和2.852 7倍(P<0.01),AZⅠmRNA水平为对照组的1.962 1和3.073 8倍(P<0.01);利用DFMO处理体外分离的上皮细胞和基质细胞,SSAT mRNA水平为对照组的1.626 7和1.773 3倍(P<0.01),SAMDC mRNA水平为对照组的1.630 0和1.730 0倍(P<0.01),AZⅠmRNA水平为对照组的71.00%和76.67%(P<0.01);DFMO处理后上皮细胞和基质细胞数目(31.00±3.00和43.67±7.51)和活力(0.26±0.03和0.36±0.05)都显著下...     

Synthetic polypeptide antagonists of the hypothalamic luteinizing hormone releasing factor

Two analogs of the hypothalamic luteinizing hormone releasing factor modified at the histidine-2 position were tested for biological activity (secretion of luteinizing hormone) in cultures of dispersed rat anterior pituitary cells. The analog in which glycine was substituted for histidine at position 2, [Gly(2)]LRF, behaves as a partial agonist releasing less than 50 percent of the luteinizing hormone secreted at maximum concentrations of the releasing factor, while the analog in which histidine at position 2 is deleted has no significant agonist activity at any of the doses tested. When added to the cultured cells at molar ratios 10(3) to 10(4) times that of the luteinizing hormone releasing factor, both analogs decrease the amount of luteinizing hormone secreted in response to the releasing factor.     

国庆1号温州蜜柑和沙田柚叶片的多胺代谢酶活性

为调控柑橘内源多胺提供参考依据,以国庆1号温州蜜柑(Citrus unshiu cv.Guoqing No.1)和沙田柚(C.grandis var.Shatinyu Hort.)的叶片为试材,研究其多胺合成酶精氨酸脱羧酶(ADC)、鸟氨酸脱羧酶(ODC)以及多胺分解酶二胺氧化酶(DAO)、多胺氧化酶(PAO)的活性....     

家兔的超数排卵

应用国产激素制剂对大耳白、青紫兰和比利时３种家兔进行了超数排卵处理，系统研究了品种、激素剂量、发情周期、重复超排间隔时间以及体重、季节等因素对超排效果的影响。实验结果表明，１）ＰＭＳＧ和ｈＣＧ对３种家兔超排处理的最适剂量有差异，大耳白兔为１３０ＩＵ剂量组最好（平均获卵２４．３８±５．５７个），青紫兰兔为１１０ＩＵ剂量组最佳（平均获卵２６．００±４．３１个），而比利时兔的剂量效应不明显（１３０ＩＵ剂量组好于其他各组，平均获卵１６．００±２．３５个）；２）同种家兔间隔１～２个情期与间隔３～４个情期重复超排效果差异不显著（Ｐ＞０．０５），且分别与各自初次超排效果相比也相差不显著（Ｐ＞０．０５）；３）发情周期不同阶段开始超排效果不同，大耳白兔和青紫兰兔发情早期至发情晚期的超排效果显著（Ｐ＜０．０５）或极显著（Ｐ＜０．０１）好于间情期；４）以１２０ＩＵ～１３０ＩＵ剂量进行超排处理，体重在２．００～２．９９ｋｇ的青紫兰兔的超排回收卵数为２６．３８±７．４７个，极显著多于体重在４．００～４．９９ｋｇ的青紫兰兔（获卵１３．７５±４．８５个）（Ｐ＜０．０１）；５）大耳白兔在１０～１２月份的超排回收卵数为２５．７３±６．２８个?     

Inhibin-mediated feedback control of follicle-stimulating hormone secretion in the female rat

The secretion of follicle-stimulating hormone (FSH) by the anterior pituitary gland is regulated by the interaction of hypothalamic and gonadal hormones. Recently, proteins termed inhibins that selectively suppress FSH secretion have been purified and characterized from the gonadal fluids of several species. Antibodies to a synthetic peptide encompassing the amino terminal 25 residues of the recently characterized porcine inhibin were used to develop a specific radioimmunoassay (RIA) for inhibin and to neutralize endogenous inhibin during the estrous cycle of the rat. The administration of 20 international units of pregnant mare serum gonadotropin (PMSG) stimulated the secretion of inhibin in intact immature female rats, whereas ovariectomy caused an abrupt decrease in plasma inhibin concentrations that were not prevented by the injection of PMSG. The infusion of a polyclonal antiserum to inhibin, from 12 noon on proestrus to 1 a.m. on the morning of estrus, as well as its acute intravenous injection during diestrus I or II, caused an increase in plasma FSH (but not luteinizing hormone) concentrations. These results support the hypothesis of a feedback loop between the release of ovarian inhibin and FSH in the female rat.     

Induction of mating behavior in rats by luteinizing hormone-releasing factor

Ovariectomized female rats treated with estrogen, in dosages too low to provoke mating, displayed this behavior when given subcutaneous injections of synthetic luteinizing hormone-releasing factor (LRF) 48 hours later. Two hours after the injection of LRF, components of female sexual behavior appeared. The lordosis reflex followed mounting by the male, and darting and hopping behavior was quite prevalent. On the other hand, treatment with estrogen followed by luteinizing hormone, follicle-stimulating hormone, or thyrotropin-releasing factor did not induce copulatory behavior. The results suggest that LRF may play a role in induction of mating behavior.     

Brain receptors sensitive to indole compounds: function in control of luteinizing hormone secretion

The placement of melatonin and of 5-hydroxytryptophol in the median eminence of castrated male rats is followed 5 days later by a significant decrease in pituitary stores of luteinizing hormone. Pituitary reserve of this hormone is also depleted after the implantation of melatonin, 5-hydroxytryptophol, and 5-methoxytryptophol in the reticular formation of the midbrain. It is suggested that these indole compounds, which are normally synthesized in the pineal gland, may intervene in the control of the secretion of luteinizing hormone, possibly by acting on specific receptors localized in the median eminence and in the midbrain.