饲喂外源性褪黑素对蛋鸭产蛋性能及生殖激素的影响

为研究通过饲喂方式给予外源性褪黑素对蛋鸭产蛋性能的影响,选取３４只体况及产蛋性能一致的产蛋期山麻鸭,随机分为两组,试验组给予褪黑素每只每天３ｍｇ,对照组不添加;两组均维持２４ｈ的光照,试验期为７周,期间统计蛋鸭采食量、产蛋量及检测相关生殖血清激素水平．结果表明,２４ｈ光照条件下,给予蛋鸭褪黑素在一定程度上降低蛋鸭产蛋性能,同时使蛋鸭血液褪黑素水平上升,雌二醇、促黄体素、孕酮水平下降,但差异均不显著（Ｐ＞０.０５）,表明通过饲喂外源性褪黑素的方式对蛋鸭生殖激素水平影响不大．．     

光照控制对蒙古羊发情排卵及相关生殖激素分泌的影响

通过模拟绵羊繁殖季节前后的光照条件,研究光照控制对蒙古绵羊血液褪黑激素(MLT)、促卵泡素(FSH)、促黄体素(LH)浓度分泌的影响,探讨光照条件在控制绵羊繁殖季节中的作用.结果表明:光照控制可诱导蒙古羊在非繁殖季节发情并排卵,对蒙古羊血液MLT分泌影响显著,而对血液FSH和LH分泌没有显著影响.     

生殖激素对龟类生殖调控的研究进展

迄今为止,已发现有11种生殖激素参与龟类生殖调控。雌二醇和睾酮在促性腺激素释放激素、卵泡刺激素和黄体生成素的调控下主导调控龟类性腺发育、配子生成、交配、产卵及子代性别决定等重要生殖环节。孕酮、前列腺素、精氨酸催产素、皮质酮、甲状腺素和褪黑激素协同调节龟类生殖活动。在人工繁殖方面,使用GnRH等有助于克服龟类繁殖障碍,提高繁殖效率。对生殖激素对龟类生殖活动的调控作用与机理及其应用的研究进展进行了综述。     

Immunohistochemical localization in the rat brain of the precursor for thyrotropin-releasing hormone

A rabbit antiserum to a peptide sequence present in the precursor for thyrotropin-releasing hormone (proTRH), deduced from cloned amphibian-skin complementary DNA, was raised by immunization with the synthetic decapeptide Cys-Lys-Arg-Gln-His-Pro-Gly-Lys-Arg-Cys (proTRH-SH). Immunohistochemical studies on rat brain tissue showed staining of neuronal perikarya in the parvicellular division of the paraventricular nucleus of the hypothalamus and the raphe complex of the medulla, identical to that already described for thyrotropin-releasing hormone (TRH). Immunostaining was abolished by preincubation with proTRH-SH (10(-6)M) but not TRH (10(-5)M). Both TRH precursor and TRH were located in neurons of the paraventricular nucleus. However, in contrast to the findings for TRH, no staining was observed in axon terminals of the median eminence. These results suggest that a TRH precursor analogous to that reported in frog skin is present in the rat brain and that TRH in the mammalian central nervous system is a product of ribosomal biosynthesis.     

Thyrotropin-releasing hormone in specific nuclei of rat brain

The regional distribution of thyrotropin-releasing hormone (TRH) in rat brain was studied. The greatest concentration of TRH was found in the median eminence. High concentrations were also found in several hypothalamic nuclei. Outside the hypothalamus, relatively large amounts of TRH were found in the septal and preoptic areas.     

不同光照时间对蛋鸭产蛋及生殖激素的影响

为研究不同光照时间对蛋鸭产蛋及生殖内分泌的影响,随机选取１２０只３３周龄健康蛋鸭,平均分成Ａ、Ｂ、Ｃ和Ｄ组,第１～４２天,光照程序分别为１１.５Ｌ∶１３.５Ｄ、１４Ｌ∶１０Ｄ、１６Ｌ∶８Ｄ和１８Ｌ∶６Ｄ（Ｌ：光照ｌｉｇｈｔ,Ｄ：黑暗ｄａｒｋ）;第４３～７０天,光照程序均为１８Ｌ∶６Ｄ,试验过程中统计产蛋量、蛋质量、耗料量,在第４２、７０天采血测定促黄体素、雌二醇、孕酮、褪黑素等血清生殖激素水平．结果表明,第１～４２天试验期间,Ｄ组产蛋率明显高于其它３组,平均日产蛋数极显著高于其它３组（Ｐ＜０.０１）,平均日产蛋数Ａ、Ｂ、Ｃ各组间差异不显著（Ｐ＞０.０５）;Ｄ组平均蛋质量为４组中最低,但各组间差异不显著（Ｐ＞０.０５）,Ｄ组料蛋比最低;第４２天测定生殖激素发现,除Ｄ组促黄体素和孕酮水平显著高于Ｂ组,孕酮水平显著高于Ａ组（Ｐ＜０.０５）外,其余各组间的血清生殖激素水平差异不显著（Ｐ＞０.０５）．第４３～７０天试验期间,各组的产蛋率、平均日产蛋数、平均蛋重和料蛋比差异不显著（Ｐ＞０.０５）;第７０天测定血清生殖激素水平,各组间差异不显著（Ｐ＞０.０５）．试验结果表明,１８ｈ持续光照能显著提高蛋鸭产蛋率和饲料回报率,提高生殖激素水平     

Detection of a gonadotropin in rabbit blastocyst before implantation

A gonadotropin similar to human chorionic gonadotropin or luteinizing hormone has been demonstrated in rabbit blastocyst prior to implantation. The gonadotropin has been detected by a radioreceptor assay for human chorionic gonadotropin with the use of the plasma membranes of bovine corpora lutea obtained during the first trimester of pregnancy. The concentrations of the human chorionic gonadotropin or luteinizing hormone per milliliter of blastocyst fluid were tenfold higher than those in the blood of pregnant rabbits on days 5 and 6 after mating.     

褪黑素及其在植物中的功能研究进展(英文)

褪黑素是一种广为人知的动物激素,在动物中由松果体合成与分泌,参与动物的昼夜节律的调节。现已发现褪黑素在高等植物中广泛存在,但是目前有关褪黑素在植物中的功能的研究还不是很多。已有的研究表明,褪黑素在植物中可能的作用有调节光周期、参与生长调节、清除活性氧、提高抗氧化酶活性等。根据近年的研究结果对植物中褪黑素的作用进行综述,重点阐述已经发现的褪黑素在植物上的功能作用,对其潜在生理功能进行了预测,并指出了目前研究中的不足,突出需要重点研究的方向。     

Brain serotonin concentration: elevation following intraperitoneal administration of melatonin

The intraperitoneal administration of melatonin to rats caused an increase in brain serotonin concentration, especially in the midbrain. This effect could be demonstrated within 20 minutes of melatonin administration and was not associated with changes in norepinephrine concentration.     

Ornithine decarboxylase stimulation in rat ovary by luteinizing hormone

In normal albino rats with a 4-day estrous cycle, the activity of ovarian ornithine decarboxylase undergoes a transitory rise on the evening of proestrus and only at that time. The response could be elicited by the administration of either luteinizing hormone or human chorionic gonadotrophin. When antiserum to luteinizing hormone was injected at 2 p.m. on the day of proestrus, the induction of ornithine decarboxylase was blocked, an indication that the enzyme is under luteinizing hormone control. The strategic positioning of the induction of ornithine decarboxylase between the normal release of luteinizing hormone and ovulation impties that putrescine is associated with the ovulatory process, and opens a new avenue of research on the control of ovulation.     

Thyrotropin-releasing hormone: biosynthesis by rat hypothalamic fragments in vitro

Biosynthesis of thyrotropin-releasing hormone (L-pyroglutamyl-L-histidyl-L-proline amide) in vitro was studied. Rat hypothalamic fragments were incubated in Krebs-Ringer bicarbonate buffer that contained either (14)C-labeled proline, histidine, or glutamic acid (the three probable precursor amino acids,) and for control purposes each of 16 other naturally occurring amino acids. A number of labeled peptides were synthesized. With the use of synthetic thyrotropin-releasing hormone, detected by the Pauly reagent or with (125)1-labeled thyrotropin-releasing hormone as a marker, thin-layer chromatograms, paper electrophoresis, and carboxymethyl cellulose ion exchange chromatography revealed that only proline, histidine, and glutamic acid were consistently incorporated into peptides associated with the thyrotropin-releasing hormone region. This synthesizing activity was found in stalk median eminence, ventral hypothalamus. and dorsal hypothalamus but not in neural lobe or cerebral cortex. Because the biosynthetic peptide has identical properties with L-pyroglutamyl-L-histidyl-L-proline amide, it is probable that rat thyrotropin-releasing hormone is similar or identical to both bovine and porcine thyrotropin-releasing hormone and that the native material is present in the pyroglutamyl form in tissues.     

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.     

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.     

Luteinizing hormone-releasing activity in hypophysial stalk blood and elevation by dopamine

Pituitary halves incubated in pituitary stalk plasma release more luteinizing hormone than their opposite halves incubated in plasma from peripheral blood. Glands incubated in stalk plasma from dopamine-treated rats release more luteinizing hormone than glands incubated in stalk plasma from untreated controls. Luteinizing hormone-releasing activity in stalk plasma may be due to the luteinizing hormone-releasing factor, and the secretion of luteinizing hormone-releasing factor may be controlled by a dopaminergic mechanism.     

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.     

Mechanism of gonadotropin action in amphibia: involvement of mitochondria

Luteinizing hormone (a pituitary gonadotropic hormone) stimulates Delta(5)-3beta- hydroxysteroid dehydrogenase activity in the microsomal fraction of frog testes when incubated together with the mitochondria; incubation together with the nuclei instead of the mitochondria does not result in increased, Delta(5)-3beta-hydroxysteroid dehydrogenase activity. The increase is not, induced by adenosine triphosphate, it appears to be hormone-specific, and it is sensitive to puromycin and actinomycin D. These data suggest that the mitochondrial DNA may be involved in mediating the action of luteinizing hormone in amphibian steroidogenesis.     

Vasopressin and neurophysin: high concentrations in monkey hypophyseal portal blood

Vasopressin and its binding protein, neurophysin, were measured by radioimmunoassay in the hypophyseal portal blood of monkeys after cannulation of individual long portal veins. Mean vasopressin concentrations (13,800 picograms per milliliter) in portal blood were more than 300 times as high as those in the systemic circulation (42 picograms per milliliter). Neurophysin concentration was approximately 25 times as high in portal as in systemic blood. By immunoperoxidase techniques, high concentrations of neurophysin were demonstrated around portal capillaries of the median eminence. These studies indicate direct secretion of vasopressin and neurophysin into the portal circulation; the quantities secreted during stress may be sufficient to exert significant effects on secretion of anterior pituitary hormone.     

Release of luteinizing hormone in male mice during exposure to females: habituation of the response

Male mice release luteinizing hormone when exposed for a short time to a female. In this experiment, multiple blood samples were withdrawn by atrial cannulas from tethered males during either continuous or intermittent exposure to nonreceptive females. After an immediate, transient release of luteinizing hormone, continuous exposure to the same female was accompanied by only random, spontaneous elevations in plasma levels of this hormone. Successive presentations of the same female at 2-hour intervals elicited gradually diminishing luteinizing hormone responses. Exposing such unresponsive males to novel, diestrous females, however, dramatically stimulated their release of the hormone. These results demonstrate habituation of a socially induced, neuroendocrine response involving reproductive hormones.     

基于尿液激素母猪发情辅助检测分析

针对传统母猪限位栏圈养查情工作量大、效率低的关键生产问题,对母猪尿液中雌二醇(E2)和促黄体生成素(LH)2种激素进行测定,研究利用激素质量浓度和水平变化规律辅助检测断奶后母猪发情行为的可行性,并为开发试纸快速检测提供参考阈值.结果表明:1)尿液中雌二醇、促黄体生成素的质量浓度和水平在发情周期内呈规律性变化,在人工常规...     

Hormonal regulation of gonadotropin receptors and steroidogenesis in cultured fetal rat tests

Gonadotropic activation of the adult rat testis in vitro and in vivo is followed by down-regulation of luteinizing hormone receptors and decreased androgen responses to subsequent hormonal stimulation. In contrast, treatment of cultured fetal testes with gonadotropins and dibutyryl adenosine 3',5'-monophosphate enhanced steroidogenic responsiveness and did not cause the luteinizing hormone-receptor loss and desensitization that is characteristic of the adult gonad. The analysis of gonadotropin receptors and action in cultured fetal testis cells facilitates developmental studies of gonadal function, and has revealed significant differences in the responses of fetal and adult Leydig cells to gonadotropic regulation.