环境内分泌干扰物对鱼类的影响

环境内分泌干扰物对水生态环境造成了严重的污染,生活在水中的鱼类也因此受到危害。从鱼类生长发育、性分化和繁殖等方面论述了内分泌干扰物对鱼类及其种群的影响,探讨了内分泌干扰物研究对于保护水生生物和渔业资源的重要性,并讨论了水体内分泌干扰物的研究趋势。     

环境内分泌干扰物对鱼类影响的研究进展

水环境中的内分泌干扰物可导致鱼类性别特征丧失和后代不能繁殖,损伤神经、免疫和内分泌系统,引起鱼类种群生存力和资源量下降。介绍了环境内分泌干扰物的概念、种类、作用机制和危害特征,着重阐述了其对鱼类生理生化的影响,讨论了环境内分泌干扰物的降解与研究前景。     

鱼类在内分泌干扰研究中的应用

鱼类在毒理学研究和生态风险评价中有重要的试验价值,是研究内分泌干扰作用的理想试验动物。本文主要综述了利用鱼类进行内分泌干扰研究的主要测试终点和敏感效应指标;重点介绍了稀有鮈鲫、斑马鱼、日本青鳉、孔雀鱼、剑尾鱼、黑头软口鲦等鱼类的主要生物学特性,以及利用它们进行内分泌干扰物的筛选与测试方面的研究成果。     

双酚A和酞酸酯对鱼类的内分泌干扰效应和繁殖毒性的研究进展

环境雌激素作为一类内分泌干扰物进入人和动物体内后能干扰机体内分泌系统的正常功能,通过多种机制表现出拟天然雌激素或者抗天然雄激素的作用。双酚A（bisphenol A, BPA）和酞酸酯（也称作邻苯二甲酸酯,Phthalic Acid Esters, PAEs）是具有雌激素类活性的环境内分泌干扰物,广泛存在于水环境中,并对水生动物,特别是鱼类的安全造成潜在威胁。本文总结了目前BPA和PAEs对鱼类毒性效应的研究成果,特别是内分泌干扰作用和生殖毒性,为评估这两类环境污染物对鱼类的影响提供参考。     

双酚A和酞酸酯对鱼类内分泌干扰效应及繁殖毒性研究

环境雌激素作为一类内分泌干扰物进入人和动物体内后,能干扰机体内分泌系统的正常功能,通过多种机制表现出拟天然雌激素或者抗天然雄激素的作用。双酚A(bisphenol A,BPA)和酞酸酯(也称作邻苯二甲酸酯,Phthalic Acid Esters,PAEs)是具有雌激素类活性的环境内分泌干扰物,广泛存在于水环境中,并对水生动物特别是鱼类的安全造成潜在威胁。本文总结了目前BPA和PAEs对鱼类毒性效应的研究成果,特别是内分泌干扰作用和生殖毒性,为评估这两类环境污染物对鱼类的影响提供参考。     

鱼类在环境污染物检测中的重要指示作用——水环境中内分泌干扰物的检测

环境内分泌干扰物广泛存在于自然水体中,影响水生动物生存和人类健康。利用鱼类检测水中内分泌干扰物是一个有效方法。本文介绍了利用鱼类评测水中内分泌干扰物的研究现状,并展望了以鱼类作为对象更加全面的评测内分泌干扰物的前景。     

水产品中内分泌干扰物残留检测方法研究进展

环境内分泌干扰物(EDCs),是一类存在于环境介质中并介导生物体内分泌激素的合成、释放、代谢、结合和排泄作用,对其后代产生有害影响的外源性化学物质;因干扰内分泌系统的过程与雌激素类似,故也被称为环境激素[1-2] 。环境内分泌干扰物分为自然存在和人为合成,人为合成的主要来源于人类广泛的农业和工业活动,如常见的有机氯农药、己烯雌酚、双酚A、多环芳烃类和多氯联苯类(PCBs)等,研究表明,其中已有300多种物质危害人类和动物的健康 [3-5] 。近年来随着环境内分泌干扰物的广泛应用以及未经处理的各类废水排放,使得各地环境受到不同程度的污染。Luo等 [6] 检测分析了湘江的21种环境内分泌干扰物的质量浓度水平,发现烷基酚的质量浓度最高,为0.8~3100 ng/L;Kumirska等 [7] 利用气相色谱质谱法分析污水处理厂的污泥和鱼塘沉积物,检出17-β-雌二醇、17-α-炔雌醇等13种环境内分泌干扰物,质量浓度为未检出~489 μg/kg。     

环境内分泌干扰物(EDCs)对水产养殖的危害

一、环境内分泌干扰物(E D C s)简介环境内分泌干扰物(EndocrineDisruptingChemicals,EDCs)是指一类外源性化合物进入机体后,具有干扰体内正常分泌物质的合成、释放、运转、代谢、结合等过程,激活或抑制内分泌系统功能,从而破坏其维持机体稳定性和调控作用的物质。EDCs可通过食     

环境内分泌干扰物对鱼类脂质代谢的影响:回顾与展望

脂肪严重沉积是当前养殖鱼类普遍发生的代谢障碍病症,其原因复杂多样。近年来,已有较多研究提示,广泛存在于自然水环境中的环境内分泌干扰物(EDCs)除了对多种鱼类的生长、发育和繁殖产生持久的慢性毒理效应之外,也对鱼类脂质代谢过程造成影响,导致脂肪沉积异常,并影响养殖鱼类的品质与食用安全性。本文首次系统回顾了近年来在EDCs影响鱼类脂质代谢研究领域中的重要研究成果,并针对持久性有机污染物(POPs)、重金属、环境雌激素和人工合成药物4大类污染物,系统总结了不同EDCs对鱼类脂质代谢的干扰作用。辨析了不同研究中EDCs对鱼类暴露方式、暴露时间和暴露浓度的差异,并由此分析同种EDC在不同的暴露环境下对鱼类脂质代谢产生的差异影响。本文在综述已有成果的基础上,提出了本领域今后的研究重点和方向,旨在为深入研究EDCs对鱼类脂质代谢的影响机制提供更多参考,进一步理解鱼类脂肪沉积的原因,为绿色可持续发展的水产养殖业提供重要的理论支持。     

鱼类生长相关激素的营养调控

<正>鱼类激素是由内分泌腺所分泌的一类具有生物活性的物质,虽然含量极低,却在鱼类整个生命活动中起重要作用。像哺乳类一样,调节鱼类生长发育的内分泌激素主要包括垂体生长激素、类胰岛素生长因子-Ⅰ和甲状腺激素。鱼类内分泌系统对营养摄入的变化非常敏感,营养状况在调控鱼类激素的合成与分泌中发挥重要作用,研究较多的有饥饿、饲料中蛋白质和碳水化合物水平等。笔者简要综述了这三种营养状况对生长内分泌激素的影响     

Coordinated expression and regulation of deiodinases and thyroid hormone receptors during metamorphosis in the Japanese flounder (<Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>)

In vertebrates, thyroid hormone receptors (TRs) and deiodinases are essential for developmental events driven by the thyroid hormones (THs). However, the significance of deiodinases during the metamorphosis of the Japanese flounder (Paralichthys olivaceus) remains unclear. Moreover, regulation and response of the TRs and deiodinases to THs in this fish are poorly understood. Therefore, we detected the expression patterns of THs, deiodinases, and TRs in drug-treated larvae and untreated larvae of P. olivaceus by using enzyme-linked immunosorbent assay and quantitative real-time PCR during P. olivaceus metamorphosis. To further understand the roles of these elements, a rescue assay was performed. Our results show the importance of THs, TRs, and deiodinases in flatfish metamorphosis. Our results also confirm that D1 and D2 activate THs and D3 plays the opposite and complementary role. Moreover, we demonstrated that both TRα and TRβ have important but different roles during P. olivaceus metamorphosis.     

Thyroid hormones down-regulate thyrotropin β mRNA level in vivo in the turbot (Psetta maxima)

Thyroid stimulating hormone (TSH) is a vertebrate pituitary heterodimeric hormone that stimulates the thyroid gland to produce the thyroid hormones, T3 and T4. We report here the cloning, by PCR on reverse-transcribed pituitary RNAs, of a 180 bp fragment of the cDNA encoding TSH subunit in the turbot (Psetta maxima). The deduced amino acid sequence displayed 66 and 75% identity with the corresponding sequence from the European eel (Anguilla anguilla) and the rainbow trout (Oncorchyncus mykiss), respectively. This cDNA was then used as a probe for densitometric analysis of individual pituitary Northern blots. TSH mRNA levels were quantified in turbot where circulating thyroid hormones were modified by dietary treatments or hormone supplementation. Recombinant rainbow trout growth hormone had no effect on circulating thyroid hormone levels or on pituitary TSH mRNA level. In turbot fed heat-treated rapeseed meal, plasma T4 levels were lowered and TSH mRNA increased more than two fold. In contrast, when turbot were fed a standard fish-meal supplemented with T3, circulating T3 levels were elevated and there was a dramatic decrease in TSH mRNA level. It is concluded that both thyroid hormones are able to down-regulate TSH mRNA level in vivo in the turbot. These results are discussed in the context of the evolution of the TH feed-back on TSH production.     

Changes in brain and pituitary GnRH levels during ovarian maturation in wild female Japanese flounder

To elucidate the role of gonadotropin-releasing hormone (GnRH) in gonadal maturation in wild female Japanese flounder Paralichthys olivaceus, we monitored changes in the levels of seabream GnRH (sbGnRH) in the olfactory bulb, telencephalon, hypothalamus, and pituitary during ovarian development together with changes in plasma levels of testosterone (T), estradiol-17β (E₂), and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP). Fish were caught offshore of the northern mainland of Japan in the Pacific Ocean at 3- to 4-week intervals between April and September by gill net. The netted fish were categorized into six groups based on ovarian stages: previtellogenic (April–early May), early yolk (April–late May), late yolk (late May–June), early spawning (June–August), late spawning (September), and termination (September) stages. The gonadosomatic index significantly increased from the previtellogenic to early spawning stages and decreased thereafter. In the olfactory bulb, no significant differences were observed in sbGnRH levels among the developmental stages. In contrast, sbGnRH levels in the telencephalon and hypothalamus were very high in the previtellogenic stage, lower in the early spawning stage, and relatively high in latter stages. sbGnRH levels in the pituitary were high in the previtellogenic stage and low in the early spawning stage. In addition, the relatively high levels of pituitary sbGnRH were found together with high plasma T, E₂, and DHP levels in fish in the late yolk stage. These results indicate that sbGnRH in the telencephalon, hypothalamus, and pituitary is involved in ovarian maturation and that sbGnRH may play an important role in the initiation of ovarian recrudescence in wild Japanese flounder.     

GnIH多肽对半滑舌鳎(Cynoglossus semilaevis)下丘脑生殖相关基因表达的影响

本研究首次通过下丘脑离体孵育的方法研究促性腺激素抑制激素(Gonadotropin-inhibitory hormone,GnIH)多肽对半滑舌鳎(Cynoglossus semilaevis)下丘脑中生殖相关基因的表达调控.研究结果显示,tsGnIH-1促进了gnrh2和gnih的表达,对gnrh3和kiss2的表达无影响;tsGnIH-2抑制了gnrh3的表达,对gnrh2、kiss2和gnih的表达无影响.GnIH多肽对生殖相关基因的不同调控表明同一前体蛋白编码的不同GnIH多肽在生殖调控中的作用不尽相同.本研究结果增加了对GnIH参与鱼类生殖调控机制的认识,为深入研究奠定了基础.     

Evidences for involvement of growth hormone and insulin-like growth factor in ovarian development of starry flounder (<Emphasis Type="Italic">Platichthys stellatus</Emphasis>)

Although gonadotrophins are major regulators of ovarian function in teleosts and other vertebrates, accumulating evidence indicates that the growth hormone (GH)-insulin-like growth factor (IGF) axis also plays an important role in fish reproduction. As a first step to understand the physiological role of the GH-IGF system in the ovarian development of starry flounder (Platichthys stellatus), the expression profiles of GH and IGF messenger RNAs (mRNAs) and plasma GH, IGF-I, estradiol-17β (E2), and testosterone (T) levels during the ovarian development were investigated. The developmental stages of ovaries were divided into five stages (II, III, IV, V, and VI) by histological analysis. The hepatosomatic index (HSI) and gonadosomatic index (GSI) values increased and peaked at stage IV and stage V, respectively, and then declined at stage VI. Pituitary GH mRNA levels decreased sharply at stage III and raised to top level at stage VI. The hepatic IGF-I mRNA levels ascended to maximum value at stage V and then declined significantly at stage VI. However, the hepatic IGF-II mRNA levels remained stable and increased significantly at stage VI. In contrast, the ovarian IGF-I mRNA levels increased gradually and peaked at stage VI. The ovarian IGF-II mRNA levels were initially stable and increased significantly at stage V until the top level at stage VI. Consistent with the pituitary GH mRNA levels, plasma GH levels reduced sharply at stage III and remained depressed until stage V and then raised remarkably at stage VI. Plasma IGF-I level peaked at stage V and then declined to initial level. Plasma E2 level peaked at stage IV and then dramatically descended to the basal level. Plasma T level peaked at stage V and then declined significantly back to the basal level. Based on statistical analysis, significant positive correlations between hepatic IGF-I mRNA and GSI, ovarian IGF-II mRNA and hepatic IGF-II mRNA, ovarian IGF-I mRNA and ovarian IGF-II mRNA, and plasma IGF-I and plasma T were observed, respectively. These results suggest that the GH-IGF system may be involved in the ovarian development of starry flounder; GH and IGFs appear to play distinct roles in the regulation of the ovarian development in paracrine/autocrine manners. These findings extend our knowledge of the roles of the GH-IGF axis on reproduction regulation in fish.     

Interaction of orexin/hypocretin-like immunoreactive neurons with melanin-concentrating hormone and α-melanocyte-stimulating hormone neurons in brain of a pleuronectiform fish, barfin flounder

Immunohistochemical localization of orexin/hypocretin in the brain of a pleuronectiform fish, the barfin flounder Verasper moseri was examined as the first step in unraveling the possible function of the hormone in the brain. Orexin-A-like immunoreactive (ir) cell bodies were found to be located in the nucleus posterioris periventricularis (NPPv) of the hypothalamus, and orexin-A-like-ir fibers were detected not only in the hypothalamus but also extensively throughout the brain. The orexin-A-like-ir cell bodies did not project their fibers to the pituitary gland. Since melaninconcentrating hormone (MCH) and α-melanocyte-stimulating hormone (α-MSH) are suggested to regulate food intake in addition to orexin/hypocretin in the teleost fish, it was examined whether neural connections exist between orexin neurons and the MCH and α-MSH neurons in the barfin flounder brain by using double-staining immunohistochemistry. Some orexin-A-like-ir fibers were in close contact with the MCH-ir and α-MSH-ir cell bodies in the hypothalamus. Moreover, a few MCH-ir and α-MSH-ir fibers were in close contact with the orexin-A-like-ir cell bodies in the hypothalamus. These results suggest that reciprocal connections exist between the orexin and MCH neurons and between the orexin and α-MSH neurons in the brain of the barfin flounder.     

Thyroidal compensation in rainbow trout (Salmo gairdneri) fed canola meal

Rainbow trout (Salmo gairdneri Richardson) were fed either a soybean mealbased (SM) or canola meal-based (CM) diet for up to 20 weeks. Plasma thyroxine (T₄) and triiodothryonine (T₃) levels were significantly lower in the CM-fed fish sampled after 12 weeks. However, there appeared to be some compensation after 12 and 20 weeks in that the thyroid hormone levels in trout fed the CM were not significantly different from those of the SM-fed fish. Nevertheless, there was marked thyroid hyperplasia and hypertrophy in the CM-fed fish sampled at 12, 16 and 20 weeks after commencement of the experiment. Moreover, the growth rate was significantly lower in the CM-fed fish in comparison to the SM-fed fish throughout the 20 week study period.Plasma T₄ levels were similar in SM-fed fish sampled 12, 16 and 20 weeks after commencement of the experiment, but plasma T₃ levels progressively increased over this period, as did the apparent activity of the thyroid tissue based on histological criteria.Fasting for up to 8 weeks resulted in the arrested growth of the SM-fed fish, and a loss in body weight of the CM-fed animals over the 8 week period of the fast. In addition, the plasma thyroid hormone levels in the fasted fish tended to be lower than in fish fed both the SM and CM diets prior to fasting, and there was histological evidence indicating a reduced activity of the pituitary-thyroid axis. However, thyroid hyperplasia and hypertrophy were still evident in the fasted fish previously fed the CM diet indicating that the adverse affects of CM diets are not completely reversible after 8 weeks.In fish fed the CM diet for 12 weeks and then the SM diet for up to a further 8 weeks (diet C-S) there was a compensatory increase in plasma thyroid hormone levels evident within 4 weeks after the change in diet, but no apparent decrease in thyroid hyperplasia or hypertrophy. In addition, in the fish fed the C-S diet there was a marked compensatory growth rate, and an increased feed: gain ratio; body weights of this group of fish were not significantly different from those of the SM-fed animals after 20 weeks of study, indicating a considerably higher growth rate over the last 8 week period.