环境激素对人类健康的危害及其作用机制

环境激素是环境中的激素类似物,它在人体和动物体内发挥着类似于激素的作用,通常称为＂外因性内分泌干扰物质＂,干扰体内正常激素的作用.该文介绍激素与环境激素的区别、环境激素的特性、种类;重点阐述环境激素的及其内分泌干扰机制;从环境激素对人类的健康,尤其是对生殖健康的危害,提出了防治环境激素污染的措施.     

畜禽养殖过程中雌激素的排放及其环境行为

由于存在广泛和较强的内分泌干扰性,环境雌激素越来越受到关注,其中人与动物排放的天然类固醇雌激素(雌酮、雌二醇和雌三醇)具有最强的干扰性。综述了畜禽养殖过程中天然雌激素的排放、危害以及其物化性质,并结合国内外近期研究阐明了天然雌激素的吸附、降解和迁移转化等环境行为。在目前雌激素研究现状的基础上,对未来的研究方向及目标提出了建议。     

环境激素浅说

１　环境激素的概念动物激素是动物的内分泌腺分泌的,通过体液运送到身体的特定作用部位,对生物的新陈代谢、生长发育等生命活动起重要调节作用的微量有机化合物。但据最近的观察和研究表明,许多种类的人工合成的化学物质,均能影响和扰乱生物体内固有的内分泌系统,导致内分泌障碍,我们称这类环境中的内分泌干扰物为环境激素。２　环境激素的种类根据“世界自然保护基金会”的调查,目前,人们已知晓的环境激素多达７２种,主要存在于二恶英类物质和人工合成的各种化学物质内,并散布于人类的生活环境中。二恶英是以两个氧原子桥结合两…     

Differential effects of Ca2+ and Mg2+ on endonuclease activation in isolated promyelocytic HL-60 cell nuclei

Ａｐｏｐｔｏｓｉｓｏｒｐｒｏｇｒａｍｍｅｄｃｅｌｌｄｅａｔｈ(ＰＣＤ)ｉｓａｐｒｏｃｅｓｓｏｆｃｅｌｌｄｅｌｅｔｉｏｎｗｈｉｃｈｏｃｃｕｒｓｉｎｒｅｓｐｏｎｓｅｔｏａｎｕｍｂｅｒｏｆｃｙｔｏｔｏｘｉｃａｎｄｐｈｙｓｉｏｌｏｇｉｃａｌｌｙｒｅｌｅｖａｎｔｓｔｉｍｕｌｉ.Ｔｈｉｓｐｒｏｃｅｓｓｉｓｃｈａｒａｃｔｅｒｉｚｅｄｂｙｓｅｖｅｒａｌｅａｒｌｙｍｏｒｐｈｏｌｏｇｉｃａｌｔｅｒａｔｉｏｎｓｉｎｃｌｕｄｉｎｇｐｌａｓｍａａｎｄｎｕｃｌｅａｒｍｅｍｂｒａｎｅｂｌｅｂｂｉｎｇ.Ｅｎｄｏｇｅｎｏｕｓｅｎｄｏ…     

环境内分泌干扰物对生殖健康影响的研究进展

环境内分泌干扰物(environmental endocrine disruptors,EEDs)是指环境中天然存在或污染的能够干扰机体内自然激素的合成、分泌、转运、结合、作用和消除等过程,表现出拟自然激素或抗自然激素的生理学作用的一类化合物。它们与人们的生活密不可分,比如邻苯二甲酸酯类(PAEs)和双酚A(BPA),就广泛存在于食品包装、儿童玩具及生活用品中。大量实验证据以及流行病学的调查表明环境内分泌干扰物对动物雌激素、睾酮、甲状腺素、儿茶酚胺等呈现显著的干扰效应,是生殖障碍、出生缺陷、发育异常、代谢紊乱以及某些恶性肿瘤的发病率增加的原因之一。本文归纳了环境内分泌干扰物(EEDs)对生殖健康影响的研究进展。     

环境激素—危险的环境污染物

激素是由人或动物内分泌腺或散在的内分泌细胞所分泌的高效能生物活性物质 ,它与神经系统密切联系 ,共同调节机体的多种功能活动 ,维持人体内环境的相对稳定。近几年来人们发现在环境中存在一些化学物质 ,它们具有类似人体激素的功能 ,有时能引起机体内分泌紊乱 ,故将其称为“环境激素”。1　环境激素的来源和作用方式环境激素是社会生产工业化的产物。特别是近 70年来 ,随着大量的化学合成物的生产、使用 ,一些具有激素功能的化合物也随之排入周围环境产生污染 ,造成巨大的危害。目前全球已合成的化学物质有 10 0 0万种 ,每年还新合成 10万…     

生长激素结合蛋白

动物的生长调控作用中垂体分泌的生长激素 (ＧＨ)起着重要的作用。ＧＨ的生理调控作用的发挥又与血液中的生长激素结合蛋白(ｇｒｏｗｔｈｈｏｒｍｏｎｅｂｉｎｄｉｎｇｐｒｏｔｅｉｎ ,ＧＨＢＰ)以及靶细胞膜上的生长激素受体 (ｇｒｏｗｔｈｈｏｒｍｏｎｅｒｅ ｃｅｐｔｏｒ,ＧＨＲ)的作用不可分割。这三者以及下丘脑的生长激素释放因子 (ＧＨｒｅｌｅａｓｅｆａｃ ｔｏｒ ,ＧＨＲＦ) ,还有垂体的生长抑素 (ｓｏｍａｔｏ ｓｔａｔｉｎ ,ＳＳ)等共同构成动物的内分泌生长轴(ｓｏｍａｔｏｔｒｏｐｉｃａｘｉｓ) ,对动物的生长发育起着决定性的…     

一篇探索真核细胞核起源的力作——读李靖炎先生的长篇近作“The primitive nucleus model and the origin of the cell nucleus”

《胞内共生与细胞研究》(《ＥｎｄｏｃｙｔｏｂｉｏｓｉｓａｎｄＣｅｌｌＲｅ ｓｅａｒｃｈ》)是由国际胞内共生学会 (ＩｎｔｅｒｎａｔｉｏｎａｌＳｏｃｉｅｔｙｏｆＥｎ ｄｏｃｙｔｏｂｉｏｌｏｇｙ ,ＩＳＥ)主办的期刊 ,它主要发表有关内共生物(ｅｎｄｏｓｙｍｂｉｏｓｅｓ)和真核细胞的起源、发展、分化、进化和系统发育的研究论文。在胞内共生和真核细胞的起源进化研究领域享有声誉。去年该杂志发表了我国学者李靖炎先生的长篇论著“Ｔｈｅｐｒｉｍｉｔｉｖｅｎｕｃｌｅｕｓｍｏｄｅｌａｎｄｔｈｅｏｒｉｇｉｎｏｆｔｈｅｃｅｌｌｎｕ…     

选择性制造血管

当组织需要氧气和养料时 ,它们释放能促进血管生长的分子。无组织特异性的血管内皮生长因子 (ｖａｓ ｃｕｌａｒｅｎｄｏｔｈｅｌｉａｌｇｒｏｗｔｈｆａｃｔｏｒ ,ＶＥＧＦ)即是其中一种。但由于不同组织对血管需求不同 ,还应存在组织特异性的血管生长因子。加利福尼亚大学的Ｌｅｌｏｕｔｅｒ及其同事首次发现此类分子内分泌腺衍生的血管内皮生长因子 (ｅｎｄｏｃｒｉｎｅ ｇｌａｎｄ ｄｅｒｉｖｅｄｖａｓｃｕｌａｒｅｎｄｏｔｈｅｌｉａｌｇｒｏｗｔｈｆａｃｔｏｒ ,ＥＧ ＶＥＧＦ)。它能特异性诱导内分泌腺毛细血管内皮细胞的增殖和迁移…     

4－壬基酚对三种水生生物的毒性影响

环境中的壬基酚(Nonylpheol,NP)主要来自于非离子表面活性剂壬基酚聚氧乙烯醚(NPEO)的生物降解。NPEOS由NP与环氧乙烷反应生成,是目前全球商用第二大类的非离子表面活性剂,因其高效、经济、具有较高性价比而广泛应用于纺织、塑料、造纸等工业、农业和日常生活中。NPEOS进入水体后可经生物降解形成代谢产物NP。众多的体内外试验证明壬基酚是一种环境内分泌干扰物,具有雌激素样活性,且在环境中难降解,造成的环境污染效应非常严重。但目前国内外对4-NP的研究多集中在其对水生生物的环境激素效应及生物累积性方面,如周忠良等就4-NP对…     

The rodent estrous cycle: characterization of vaginal cytology and its utility in toxicological studies

While an evaluation of the estrous cycle in laboratory rodents can be a useful measure of the integrity of the hypothalamic-pituitary-ovarian reproductive axis, it can also serve as a way of insuring that animals exhibiting abnormal cycling patterns are disincluded from a study prior to exposure to a test compound. Assessment of vaginal cytology in regularly cycling animals also provides a means to establish a comparable endocrine milieu for animals at necropsy. The procedure for obtaining a vaginal smear is relatively non-invasive and is one to which animals can become readily accustomed. It requires few supplies, and with some experience the assessments can be easily performed in fresh, unstained smears, or in fixed, stained ones. When incorporated as an adjunct to other endpoint measures, a determination of a female's cycling status can contribute important information about the nature of a toxicant insult to the reproductive system. In doing so, it can help to integrate the data into a more comprehensive mechanistic portrait of the effect, and in terms of risk assessment, may provide some indication of a toxicant's impact on human reproductive physiology.     

玩具对小鼠生长发育及繁殖性能的影响

目的：探讨玩具对实验小鼠生长发育及繁殖性能的影响。方法选取7-8周龄ICR小鼠,在生产过程中加入玩具进行干预,观测其对小鼠生长发育及繁殖性能方面指标的影响。结果除产仔数外,实验组各项繁殖性能指标均优于对照组,且差异显著（ P ＜0.05）。并且随干预时间延长,差异的显著性有进一步增加的趋势。实验组小鼠的生长发育水平相比于对照组有明显变化,且表现出有随干预时间延长而产生差异的趋势,但目前尚无统计意义（ P ＞0.05）。结论玩具对ICR小鼠的生长发育及繁殖性能有一定程度的积极影响,在小鼠的生产和饲育过程中值得借鉴。     

Contributions of juvenile and adult diet to the lifetime reproductive success and lifespan of a spider

Food availability can vary widely for animals in nature and can have large effects on growth, reproduction and survival. While the consequences of food limitation for animals have been extensively studied, significant questions still remain including how ontogenetic variation in food availability contributes to lifetime reproductive success. We tested the effects of juvenile and adult food limitation on the lifetime reproductive success and lifespan of bridge spiders, Larinioides sclopetarius. Food availability was manipulated (low or high) over the entire juvenile and adult stage in a full‐factorial design and reproductive output and lifespan were measured. Juvenile and adult food limitation both reduced lifetime egg and hatchling production with effect sizes that were not significantly different from each other. Unlike some other arthropods, where juvenile food limitation reduces fecundity by reducing adult body size, body size was not affected by juvenile diet in bridge spiders. Clutch size was also significantly reduced by both juvenile and adult food limitation. The effect of adult diet on clutch size was stronger than that of juvenile diet. Juvenile and adult food limitation both extended total lifespan, and adult food limitation extended adult longevity (i.e. time from maturation to death). However, juvenile food limitation decreased adult longevity, in contrast to what would be predicted by dietary or caloric restriction. Compensatory feeding and growth are widely recognized mechanisms through which animals can ameliorate some of the negative effects of periods of food limitation. Yet our results combined with studies of a range of other species suggest that there may be lasting consequences of juvenile food limitation on lifetime reproductive success that cannot be compensated for by adult feeding in some species.     

Morphological changes of female reproductive organs of Japanese monkeys with reproductive conditions

Macroscopic and histological changes were examined on the female reproductive organs of Japanese monkeys (Macaca fuscata) with varying reproductive status in enclosed and provisioned troops. The weight and size of reproductive organs are described. The size of uterus declined in 2–3 months after parturition. The number of parturition was roughly estimated by degrees of sclerosis in myometrial vessels. The nipple length of parous animals was longer than that of nulliparous ones. The bilateral difference in the length (more than 3 mm) between nipples indicated the experience of nursing. Interpreting ovaries on the basis of macroscopic examination alone was less precise. The present results suggested that the female sexual maturity and the experience of nursing can be estimated by the measurement of reproductive organs in the Japanese monkey.     

Correlates of sexual and maternal competence in captive gorillas

The captive gorilla population may not be self-sustaining, in part because the overall birth rate is low and because many potential founders have failed to reproduce. We used questionnaires to collect standardized biographies of every gorilla held in North America. These biographies were searched for factors associated with reproductive success or failure. Captive-born gorillas are reproducing at least as well as wild-borns, when reproductive success is expressed as number of infants per year of reproductive opportunity. Mother-reared females are reproductively more successful than hand-reared females, but there is no difference in the reproductive success of mother-reared and hand-reared males. Social access to conspecifics in the 1st year is associated with higher reproductive success, at least for females. Reproductively successful and unsuccessful gorillas of both sexes have had equal access to potential mates, but unsuccessful animals are less likely than successful ones to exhibit normal sexual behavior. We conclude that many cases of reproductive failure are due to deficits in sexual behavior, which in turn may result from lack of early social experience with conspecifics. Some reproductive failure involves medical problems; interventive diagnostic techniques continue to be useful, if only to identify healthy individuals that can be managed intensively. The probability that a female will be a competent mother is not affected by her being wild-born or captive-born, or mother-reared or hand-reared.     

Neoplasms of the reproductive tract: the role of hormone exposure

Cancers of the reproductive system are a major source of morbidity and mortality among women worldwide. Because the uterus, ovaries, and cervix are hormonally responsive tissues, exposure to endogenous or exogenous sex steroids can profoundly affect the carcinogenic process. Animal models developed to date provide valuable but imperfect systems in which to study neoplasms of the reproductive tract. Nonhuman primate models share the unique primate-specific endometrial physiology of humans, but rarely develop neoplasms of the reproductive tract. Therefore a surrogate marker approach is required for the study of hormonally induced cancer risk in primates. Rodents provide practical models in which tumorigenesis can be assayed in a short time and, with appropriate interpretation, can be used for assessment of risk, prevention, and therapeutic strategies. In addition to the spontaneous strain-dependent incidence of female reproductive cancers, the classical chemical and hormonal carcinogenesis models, and the use of xenograft approaches, novel genetically modified animals provide unique insights into relevant molecular mechanisms. Caveats in the use of rodent models include anatomical differences from the human reproductive tract, the greater possibility of different metabolic responses to hormonal agents than humans, strain variations in tumor type and hormonal responsiveness, and unexpected tumor phenotypes in genetically modified animals. Reported nonmammalian models are limited primarily to the study of ovarian carcinogenesis. Recent progress in the understanding of cervical carcinogenesis is encouraging. Unmet needs in this area of research include models of early events in ovarian carcinogenesis and strongly predictive models of endometrial cancer risk. Nonhuman primates remain indispensable for the study of some aspects of reproductive pathophysiology, but the best understanding of carcinogenesis in the reproductive tract requires a broad approach using complementary human, nonhuman primate, and nonprimate studies.     

Reproductive biology of the arctic collembolan Hypogastrura tullbergi

Terrestrial organisms of the Arctic are faced with strong climatic fluctuations. Predictable seasonality with cold/long winters and short/cool summers are combined with unpredictable between and within year variation. This indicates that various selection pressures act on the reproductive strategies of the populations. The arctic collembolan Hypogastrura tullbergi reproduces in a short period following snow melt. Hatching occurs in late summer, the animals grow to adult size within their second summer and reproduce for the first time in the beginning of their third summer. We performed several experiments to determine the reproductive investment and proximate mechanism that regulate timing and duration of reproduction. We found that H. tullbergi entered a reproductive diapause when reared at constant temperature, a diapause that was terminated by a cold exposure (winter). Surprisingly, cold exposure of small juveniles may also prevent development of a reproductive diapause in adults. Thus, the life-cycle normally spanning 2 yr can potentially be reduced to one year if the overwintering juveniles reach maturity before the end of the reproductive period in the field. After termination of the diapause, the animals reproduced up to 3 times during a period of 6 weeks at 15°C. This reproductive period was considerably longer (measured in degree days) than the one observed in the field. Our results suggested that temperature quiescence, i.e. the inability to reproduce under a certain temperature threshold, may adjust the termination of the reproductive period with current temperature before a new diapause occurs in late summer. The cost of reproduction was low and suggests that it can be adaptive to spread reproduction over more than one year. The results are discussed in relation to the arctic climate and strategies favoured by unpredictable and predictable (seasonal) variations in the environment. The present study forms part of a larger investigation on population dynamics and life history strategies of H. tullbergi from the Arctic.     

Comparison of male reproductive parameters in three rat strains: Dark Agouti, Sprague-Dawley and Wistar

The choice of experimental animal can have a large impact on experimental results, an example is the anecdotal evidence suggesting that Dark Agouti (DA) rats have a lower reproductive capacity than other rat strains. In this paper we report on an investigation into male reproductive characteristics in three rat strains--Wistar, Sprague-Dawley (outbred strains) and DA (an inbred strain). Reproductive organ weights, blood testosterone levels and sperm counts were measured in mature age-matched male rats. DA animals had significantly smaller testis weights than the Sprague-Dawley and Wistar animals, and this did not appear to be related to the overall smaller body mass of the DAs. There were no differences between the three strains in testicular histology or sperm counts (per gram testis). Although there was also no significant difference in epididymal sperm count, the DA animals had a much greater variability in sperm count than the other strains. There were no differences in relative (to body weight) epididymal, seminal vesicle or ventral prostate weights or in the blood testosterone levels. These results suggest that differences in reproductive capacity in DAs are neither the result of morphological differences in the reproductive organs nor in circulating testosterone levels. Sperm production appears to be normal but the lowered testicular weight and variability in epididymal sperm counts suggests that there are other factors in the testicular or epididymal environment which alter male reproductive function.     

The social structure and dominance hierarchy of the Mashona mole-rat, Cryptomys darlingi (Rodentia: Bathyergidae) from Zimbabwe

Cryptomys darlingi is a social subterranean rodent mole which inhabits the mesic regions of south-eastern and central Africa. Mashona mole-rats live in small colonies (5-9 animals) in which reproduction is normally restricted to the largest male and female in the colony. The non-reproductive members in a mature colony cannot be placed into clearly defined work-related groups based on body mass.
The dominance hierarchy of a young colony was found to be linear, with a value of 1.00 calculated from Landau's linearity index, while that of a mature colony of nine mole-rats was almost linear (0.77). Dominance was found to be related to gender in the mature colony, with males more dominant than females, and to age in the young colony. The reproductive mole-rats are the dominant animals within their respective genders. Dominance appears to correlate positively with body mass (rs = 0.77 in the mature colony and rs = 0.93 in the young colony).
Popularity studies show that smaller animals and females tend to be more popular than the larger massed individuals or males. In the mature colony which contained predominantly adult animals, the reproductive pair was among the least popular. While in the young colony, composed predominantly of sub-adult and juvenile animals, the reproductive pair was the most popular.
Social organization within Mashona mole-rat colonies is compared with other southern African Cryptomys species.     

Prenatal programming of reproductive neuroendocrine function: the effect of prenatal androgens on the development of estrogen positive feedback and ovarian cycles in the ewe

Exposure of the female ovine fetus to male hormones during a sensitive window of in utero life causes disruption to reproductive function. In some animals, androgen exposure completely abolishes reproductive cycles, but in others, cycles are progressively lost with age. The present study tested two predictions: that noncycling, androgenized animals are unable to respond to estrogen with a preovulatory-like surge of LH (estrogen positive feedback), and that the androgenized animals that exhibit a progressive loss of cycles also show a progressive loss of estrogen positive feedback. Androgenized ewes were generated by injection of their mothers with testosterone propionate twice per week from Day 30 to Day 90 of pregnancy (term, 147 days). Control ewes received no injections. Whether ewes could exhibit estrogen positive feedback was tested on five occasions before puberty (30 wk) and once during the anestrous period. All control animals had repeated reproductive cycles in both the first and second breeding season, and all showed robust LH surges during test periods. Despite the fact that 64% of androgenized animals showed reproductive cycles, estrogen positive feedback could be demonstrated in only 6.1% of trials. Subsequent experiments revealed that the lack of response to estrogen in androgenized animals was not because of pituitary insensitivity to GnRH, a requirement for higher concentrations of estrogen, or a surge that was delayed relative to the time of estrogen administration. The mechanisms by which some androgenized ewes can produce normal reproductive cycles in the apparent absence of estrogen positive feedback are currently unknown.