EFFECT OF CHRONIC LOW-DOSE PHTHALATE EXPOSURE ON THE IMMATURE PRIMATE TESTIS

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 为子项目列出的总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 本探索性研究项目的目的是在一种新型异种移植模型系统中研究长期暴露于邻苯二甲酸酯对幼年灵长类动物睾丸的影响。在环境中接触生殖有毒物质对人类健康是一个严重的问题，并与男性生育力明显下降和睾丸肿瘤增加有关。邻苯二甲酸酯被广泛用作消费品中的增塑剂，并可渗入环境中，导致大量人体暴露，特别是在儿童时期和需要长期导管插入或静脉注射治疗的儿科患者中。邻苯二甲酸二（2-乙基己基）酯（DEHP）是最普遍的邻苯二甲酸酯，其代谢物MEHP是已知的睾丸毒物。邻苯二甲酸二丁酯（DBP）通常存在于个人护理产品中，胎儿暴露于DBP会影响大鼠雄性生殖道发育。从历史上看，在啮齿动物妊娠期暴露后，对邻苯二甲酸酯的生殖毒理学研究进行了评价，但生殖器官代谢和敏感性的种属特异性差异表明，在啮齿动物模型中获得的结果可能无法很好地外推至人类。由于流行病学研究将儿童期邻苯二甲酸酯暴露与人类男性生殖发育障碍联系起来，因此显然需要在灵长类动物模型中进行研究，正如NTP-CERHR DEHP生殖和发育毒性专家小组所强调的那样。在这个修订的探索性项目中，我们建议利用我们实验室开发的一种新型灵长类动物睾丸组织异种移植系统来研究DEHP和DBP对未成熟恒河猴睾丸成熟和睾丸功能的影响。具体目标1将检验暴露于环境相关浓度的DEHP或DBP将对睾丸体细胞功能和生殖细胞发育产生不利影响的假设。具体而言，将来自婴儿和幼年猴的睾丸组织异位移植到小鼠宿主中，并暴露于不同剂量的DEHP或DBP 3个月。在不同时间点，将在处理组织和对照组织中比较支持细胞成熟、间质细胞的类固醇生成功能和外源性促性腺激素诱导的生殖细胞分化，以评估慢性邻苯二甲酸酯暴露的潜在影响。具体目标2将研究幼年灵长类动物睾丸中邻苯二甲酸酯毒性的潜在机制。将通过微阵列分析评价邻苯二甲酸酯诱导的幼猴睾丸组织中整体基因表达模式的变化，并通过RT-PCR确认。将特别注意参与类固醇生成的基因的差异表达。该探索性项目的成功完成将提供对邻苯二甲酸酯敏感性的深入了解，表征对睾丸体细胞成熟的影响，并开始阐明未成熟灵长类动物睾丸中邻苯二甲酸酯毒性的分子机制。拟议项目的结果将为今后在发育中的灵长类动物中进行的研究提供基础。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The objective of this exploratory research project is to study the effects of chronic exposure to phthalate esters on the infant primate testis in a novel xenograft model system. Environmental exposure to reproductive toxicants is of serious concern to human health and has been implicated in both the apparent decline of male fertility and a rise in testicular neoplasms. Phthalate esters are widely used as plasticizers in consumer products and can leach into the environment, resulting in significant human exposure, especially during childhood and in pediatric patients requiring long-term catheterization or intravenous treatments. Di-(2- ethylhexyl) phthalate (DEHP) is the most ubiquitous phthalate and its metabolite MEHP is a known testicular toxicant. Di-n-butyl phthalate (DBP) is commonly found in personal care products and fetal exposure to DBP affects male reproductive tract development in rats. Historically, research into the reproductive toxicology of phthalates has been evaluated following gestational exposure in rodents, but species-specific differences in metabolism and sensitivity of the reproductive organs suggest that results obtained in rodent models may not extrapolate well to humans. As epidemiological studies link phthalate exposure during childhood to disturbances of human male reproductive development, there is a clear need for studies in primate models, as emphasized by the NTP-CERHR Expert Panel on the Reproductive and Developmental Toxicity of DEHP. In this revised exploratory project we propose to utilize a novel primate testis tissue xenografting system developed in our lab to study the effect of DEHP and DBP on testicular maturation and testis function in immature rhesus monkey testes. Specific aim 1 will test the hypothesis that exposure to environmentally relevant concentrations of DEHP or DBP will adversely affect testicular somatic cell function and germ cell development. Specifically, testis tissue from infant and juvenile monkeys will be ectopically grafted to mouse hosts and exposed to various doses of DEHP or DBP for 3 months. At various time points, Sertoli cell maturation, steroidogenic function of Leydig cells, and exogenous gonadotropin-induced germ cell differentiation will be compared in treated and control tissue to assess the potential effects of chronic phthalate exposure. Specific aim 2 will investigate the mechanisms underlying phthalate toxicity in the infant primate testis. Phthalate-induced changes in global gene expression patterns in testis tissue from infant monkeys will be evaluated by microarray analysis and confirmed by RT-PCR. Special attention will be given to differential expression of genes involved in steroidogenesis. Successful completion of this exploratory project will provide insights into the sensitivity to phthalate esters, characterize effects on testicular somatic cell maturation, and begin to elucidate the molecular mechanisms underlying phthalate toxicity in the immature primate testis. Results from the proposed project will provide the basis for future studies performed in the developing primate.