邻苯二甲酸二乙基己酯体内代谢和毒性机制研究进展

塑化剂被广泛用于各种塑料制品当中,其中以邻苯二甲酸二乙基己酯(DEHP)最为典型。随着食品中添加塑化剂的新闻不断被曝光,塑化剂对人体健康的危害逐渐引起大众关注。塑化剂及其体内代谢物在体内的蓄积可导致多个器官的损伤。塑化剂生殖器官蓄积可造成生殖系统明显的损伤,在肝脏累积可导致氧化应激而引发肝细胞凋亡,同时塑化剂又能作为佐剂影响免疫系统。该文将就DEHP的生殖毒性、肝脏毒性和免疫毒性及其有关机制进行了系统阐述。     

邻苯二甲酸丁苄酯对小鼠精子的影响

邻苯二甲酸丁苄酯(butyl benzyl phthalate，BBP)属于邻苯二甲酸酯类(PAES)化合物，是目前被怀疑具有雌激素作用的70种化合物之一。目前，Funabashi等研究表明BBP可以加强视叶前区和前脑下垂体孕酮受体mRNA表达，由此显示出雄性雌激素活性，导致雄性动物雌性化。此外BBP可以导致大鼠睾丸损伤，     

三硝基甲苯对雄性生殖毒性的研究

急性、亚急性和亚慢性TNT染毒大鼠睾丸铜锌含量和多种酶活性皆有所变化;睾丸和血清睾酮含量下降。大鼠辜丸游离间质细胞与TNT共同孵育时,睾酮形成量明显下降;间质细胞与TNT孵育后,活性氧与脂质过氧化阳性物质含量明显增加。补锌在一定程度上能拮抗TNT对大鼠的生殖毒性。横断面调查表明,TNT接触男工自觉性功能降低者增加,血清睾酮含量下降,精液常规检查有阳性所见。     

羟基脲对雄性大鼠的生殖毒性

目的观察羟基脲(HU)对雄性大鼠的生殖毒性。方法雄性大鼠分别腹腔注射HU×100、200和400mg·kg-1,连续10d。末次给药后分别于d9、d23处死动物。结果停药d9时,200、400mg·kg-1组不活动精子增加明显(P<0.05或P<0.01);停药d23时,各给药组睾丸脏/体比都明显下降(P<0.05或P<0.01);400mg·kg-1组附睾脏/体比下降明显(P<0.05),并且仍然有大量不活动精子(P<0.01);200、400mg·kg-1组精子计数明显减少(P<0.01);随给药浓度增加,各组精子畸形数量增加(P<0.01)。结论雄性大鼠连续10d腹腔注射羟基脲100mg·kg-1以上,对生殖系统产生明显毒性。     

邻苯二甲酸二-（2-乙基己基）酯对小鼠胚胎致畸作用和心肌细胞的毒性

邻苯二甲酸酯类被广泛用作增塑剂，在某些塑料产品中，含量甚至高达50％。由于其应用广泛，及易于从塑料中迁移出来，故对环境污染严重。而邻苯二甲酸二-(2-乙基己基)酯(DEHP)的用量占了增塑剂的25％，主要用于食品包装和医用器材等。动物实验表明邻苯二甲酸酯类具有致畸性，亦有资料表明它是内分泌干扰物。     

邻苯二甲酸酯类化合物的雄性生殖毒性

邻苯二甲酸酯类化合物(PAEs)属于芳香族二羧酸酯,多为高沸点、低蒸气压液体,对塑料的稳定性起着重要作用,广泛用作多种塑料膜的增塑剂,特别用于纤维素与乙烯树脂,以增加其韧性和柔性。鉴于食品包装的需要,其中许多已做过急性毒性及慢性饲养试验,其毒性均较低 1978年美国国际商业局公布的PAEs产量约为200万吨。1987～1989年我国平均年产量约为18万     

邻苯二甲酸二-2-乙基已酯对雄性大鼠的生殖毒性

邻苯二甲酸二－２－乙基乙酯（ＤＥＨＰ）染毒期间,大鼠睾丸和附睾严重萎缩;附睾尾精子数量显著减少,精子死亡率和畸形率明显增高;血清和睾丸内睾酮明显下降;睾丸乳酸脱氢酶（ＬＤＨ）和葡萄糖－６－磷酸脱氢酶（Ｇ６ＰＤＨ）活性显著升高;存在剂量－反应和时间－效应关系。恢复期,除Ｇ６ＰＤＨ外,其它观察指标均恢复到对照组水平。提示短期暴露ＤＥＨＰ引起的雄性生殖毒性为可逆性损伤     

低剂量邻苯二甲酸二(2-乙基)己酯对老年大鼠前列腺的促增生作用

目的评价环境暴露剂量的邻苯二甲酸二(2-乙基)己酯(DEHP)对老年大鼠前列腺的促增生作用及机制。方法 32只1.5岁龄老年雄性SD大鼠随机分成4组,每组8只,分别ig给予DEHP(30,90和270μg·kg~(-1))或溶媒,每天1次,连续4周。于末次给药24 h后将大鼠麻醉,而后(1)腹主动脉采血,采用ELISA检测血清中睾酮(T)、雌二醇(E2)和泌乳素(PRL)水平;(2)处死后取前列腺,分叶,称重、测量体积,计算脏器系数;(3)制作前列腺组织病理切片,HE染色后用显微镜观察组织形态改变,并利用显微图像分析软件分析前列腺上皮高度变化。结果与溶媒对照组比较,DEHP 270μg·kg~(-1)组前列腺系数、背侧前列腺质量和背侧前列腺系数均显著增加(P<0.05);DEPH各剂量组腹侧前列腺上皮高度明显升高(P<0.01);DEHP 270μg·kg~(-1)组背侧前列腺上皮高度明显升高(P<0.01);DEHP各剂量组E2,PRL和T水平均无显著改变,但DEHP 30和270μg·kg~(-1)组E2/T比值显著增加(P<0.05)。结论低剂量DEHP对老年大鼠前列腺具有促增生作用,该作用可能与其影响内源性激素的相对水平有关。     

Effects of di-(2-ethylhexyl) phthalate on the hypothalamus-pituitary-ovarian axis in adult female rats

Di-(2-ethylhexyl) phthalate (DEHP), an environmental endocrine disruptor, is widely present in the environment and some products with phthalate plasticizer. It has become a serious problem in recent years. The effect of DEHP on female reproductive system is still not well-studied. This study was to investigate the effects of DEHP on hypothalamus-pituitary-ovarian axis in adult female rats. Compared with control rats, the DEHP-treated rats showed: (1) lower body weight; (2) lower organ coefficient of ovary; (3) higher GnRH level in the hypothalamus; (4) higher mRNA and protein levels of GnRHR in the pituitary; and (5) lower serum sex hormone levels. Our data reveal that DEHP exposure may lead to the disruption of estrogen biosynthesis pathways in female rats and imbalance of hypothalamus-pituitary-ovarian axis. DEHP may impose negative influence on the development and function of the reproductive system in female rats.     

Differential developmental toxicities of di‐n‐hexyl phthalate and dicyclohexyl phthalate administered orally to rats

The objective of this study was to evaluate the developmental toxic potential of di‐n‐hexyl phthalate (DnHP) and dicyclohexyl phthalate (DCHP) in rats. Pregnant Sprague–Dawley rats were exposed to DnHP or DCHP at doses of 0 (olive oil), 250, 500 and 750 mg kg^–1 per day, by gavage, on gestational days (GD) 6–20. Maternal food consumption and body weight gain were significantly reduced at 750 mg kg^–1 per day of DnHP and at the two high doses of DCHP. Slight changes in liver weight associated with peroxisomal enzyme induction were seen in dams treated with DnHP or DCHP. DnHP caused dose‐related developmental toxic effects, including marked embryo mortality at 750 mg kg^–1 per day, and presence of malformations (mainly cleft palate, eye defects and axial skeleton abnormalities) and significant decreases in fetal weight at 500 and 750 mg kg^–1 per day. Significant delay of ossification and increase in the incidence of skeletal variants (e.g. supernumerary lumbar ribs) also appeared at 250 mg kg^–1 per day. DCHP produced fetal growth retardation at 750 mg kg^–1 per day, as evidenced by significant reduction of fetal weight. DnHP and DCHP induced a significant and dose‐related decrease in the anogenital distance of male fetuses at all doses, and there was a significant increase in the incidence of male fetuses with undescended testis at 500 and 750 mg kg^–1 per day of DnHP. In conclusion, DnHP showed clear embryolethality and teratogenicity, but not DCHP. There was evidence that both phthalates could alter the development of the male reproductive system after in utero exposure, DnHP being much more potent than DCHP. Copyright © 2009 John Wiley & Sons, Ltd.     

邻苯二甲酸二丁酯对青春期雄性大鼠的毒性研究

目的探讨邻苯二甲酸二丁酯(di-n-butyl phthalate,DBP)对青春期雄性大鼠的系统毒性。方法用DBP灌胃染毒雄性Wistar大鼠8周,剂量分别为250、5001、000 mg/(kg.d)。观察临床症状,动物体重增长,血常规,血清生化,血Zn,解剖及组织病理学等指标。通过剂量-效应关系的分析,求出基准反应(benchmark response,BMR)为10%的基准剂量(benchmark dose,BMD)及95%可信限的下限值(benchmark dose lower bound,BMDL)。结果研究发现具有剂量相关的效应终点有体重、血清尿素氮含量,血清Zn含量,睾丸系数,肾脏系数和肝脏系数,其BMDL分别为408.2,57.7,99.0,263.3,103.1,24.3 mg/(kg.d)。结论DBP对雄性青春期大鼠具有一般毒性。DBP对雄性青春期大鼠一般毒性的最低可观察毒性作用剂量水平(lowest observed adverse effect level,LOAEL)为250 mg/(kg.d),BMD和BMDL分别为42.4和24.3 mg/(kg.d)(根据肝脏系数),同时肝脏系数为最敏感效应指标。研究结果显示,BMDL评价方法较LOAEL方法更为敏感。     

Effects of dietary genistein exposure during development on male and female CD (Sprague-Dawley) rats

Genistein is a naturally occurring isoflavone that interacts with estrogen receptors and multiple other molecular targets. Human exposure to genistein is predominantly through consumption of soy products, including soy-based infant formula and dietary supplements. A dose range-finding study was conducted as a prelude to a multigeneration bioassay to assess potential toxicities associated with genistein consumption. Genistein was administered in a soy- and alfalfa-free diet at 0, 5, 25, 100, 250, 625, or 1250 ppm to pregnant dams starting on Gestation day 7 and continuing throughout pregnancy. Dietary exposure of the dams continued through lactation, and pups were maintained on the same dosed feed as their mother after weaning until sacrifice at Postnatal day 50. Body weight and feed consumption of the treated dams prior to parturition showed a decreasing trend with a significant reduction at the highest dose. Litter birth weight was depressed in the 1250 ppm dose group, and pups of both sexes in that dose group had significantly decreased body weights relative to controls at the time of sacrifice. The most pronounced organ weight effects in the pups were decreased ventral prostate weight in males at the 1250 ppm dose and a trend toward higher pituitary gland to body weight ratios in both sexes. Histopathologic examination of female pups revealed ductal/alveolar hyperplasia of the mammary glands at 250 to 1250 ppm. Ductal/alveolar hyperplasia and hypertrophy also occurred in males, with significant effects seen at 25 ppm and above. Abnormal cellular maturation in the vagina was observed at 625 and 1250 ppm, and abnormal ovarian antral follicles were observed at 1250 ppm. In males, aberrant or delayed spermatogenesis in the seminiferous tubules relative to controls was observed at 1250 ppm. There was a deficit of sperm in the epididymis at 625 and 1250 ppm relative to controls, although testicular spermatid head counts and epididymal spermatozoa counts did not show significant differences from controls at these doses. Both sexes showed an increase in the incidence and/or severity of renal tubal mineralization at doses of 250 ppm and above. Dietary genistein thus produced effects in multiple estrogen-sensitive tissues in males and females that are generally consistent with its estrogenic activity. These effects occurred within exposure ranges achievable in humans.     

Systematic reviews and meta-analyses of human and animal evidence of prenatal diethylhexyl phthalate exposure and changes in male anogenital distance

Male reproductive alterations found in animals and humans following in utero phthalate exposure include decreased anogenital distance (AGD) and other reproductive-tract malformations. The aim of this investigation was to conduct systematic reviews of human and animal evidence of the effect of in utero exposure to diethylhexyl phthalate (DEHP) on anogenital distance (AGD) in males. PubMed, Embase, and Toxline were searched for relevant human and experimental animal studies on August 15, 2016. Search results were screened for relevance, and studies that met the inclusion criteria were evaluated for quality and data extracted for analysis. Confidence in the human and animal bodies of evidence was assessed and hazard conclusions reached by integrating evidence streams. The search yielded 6 relevant human studies and 19 animal studies. Meta-analysis of 5 human observational prospective cohort studies showed that increased maternal urinary concentrations of DEHP metabolites were associated with decreased AGD in boys (?4.07 [CI, ?6.49 to ?1.66] % decrease per log₁₀ rise in DEHP metabolites). Meta-analysis and meta-regression of the 19 experimental animal studies found reduced AGD with DEHP treatment, with a dose-response gradient, and with heterogeneity explained by species and strain. There is a moderate level of evidence from human investigations and a high level of data from animal studies that in utero exposure to DEHP decreases AGD. Based upon the available human and animal evidence, and consideration of mechanistic data, DEHP is presumed to be a reproductive hazard to humans on the basis of effects on AGD.     

Hazard to the developing male reproductive system from cumulative exposure to phthalate esters—dibutyl phthalate,diisobutyl phthalate,butylbenzyl phthalate,diethylhexyl phthalate,dipentyl phthalate,and diisononyl phthalate

Phthalate esters are found in a wide variety of consumer and food packing products. Hence there is widespread exposure of the human population to these chemicals. Some of the phthalate esters are known to be toxic to the developing male reproductive system. This paper derives a reference dose (RfD) for each of the phthalate esters (dibutyl phthalate, diisobutyl phthalate, butylbenzyl phthalate, diethylhexyl phthalate, dipentyl phthalate, and diisononyl phthalate) that cause these effects. As these phthalate esters cause similar adverse biological effects and have the same mechanism of action, it is appropriate in a risk assessment to consider the potential adverse effects from cumulative exposure to these chemicals using a dose addition model. This paper provides examples of a cumulative risk assessment using the hazard index and relative potency approaches from the RfDs derived from studies in laboratory animals and exposure information in people. The results of the cumulative risk assessments for both a US and a German population show that the hazard index is below one. Thus it is unlikely that humans are suffering adverse developmental effects from current environmental exposure to these phthalate esters.     

A dose response study following in utero and lactational exposure to di-(2-ethylhexyl) phthalate (DEHP): reproductive effects on adult male offspring rats

The reproductive effects of in utero and lactational exposure to di-(2-ethylhexyl) phthalate (DEHP) in adult male offspring rats were investigated. The selected endpoints included reproductive organ weights, testicular function, hormonal status, sexual behaviour and fertility. Two wide ranges of doses, low and high, were tested. Female Wistar rats were treated daily with DEHP and peanut oil (vehicle control) by gavage from gestation day 6 to lactation day 21. The low-doses were 0.015, 0.045, 0.135, 0.405 and 1.215 mg DEHP/kg body weight (bw)/day, and the high-doses were 5, 15, 45, 135 and 405 mg DEHP/kg bw/day. A reduction in daily sperm production of 19-25% in relation to control was observed in animals exposed to 15, 45, 135 and 405 mg/kg/day. Quantitation of specific cell types shows that the observed effects in daily sperm production are not related to changes in the number of Sertoli cells or their capability to support early stages spermatocytes. A low incidence of cryptorchidism was observed in DEHP exposed groups with a lowest observed adverse effect level of 5mg/kg/day. Serum testosterone concentration was similar to control at most doses but was significantly increased at 0.045, 0.405 and 405 mg DEHP/kg/day. In spite of this effect, the weight of seminal vesicle with coagulating glands was significantly reduced at 405 mg/kg/day. Testis, epididymis and prostate weights were similar among groups. Fertility and sexual behaviour were not affected by DEHP treatment at any dose. Overall, our results show that in utero and lactational DEHP exposure reduces daily sperm production and has the potential to induce reproductive tract abnormalities (of which cryptorchidism seems to be the most sensitive in our rat strain) in male offspring rats. The lowest observed adverse effect levels (LOAELs) for these effects were 15 and 5 mg/kg/day, respectively. Therefore, the no observed adverse effect level (NOAEL) for this study can be set at 1.215 mg/kg/day.     

Developmental effects of prenatal di-n-hexyl phthalate and dicyclohexyl phthalate exposure on reproductive tract of male rats: Postnatal outcomes

The present study is to investigate the effects of in utero di-n-hexyl phthalate (DHP) and dicyclohexyl phthalate exposure (DCHP) on the development of male reproductive tract at prepubertal, pubertal and adult stages. Pregnant rats were exposed to DHP and DCHP at doses of 0, 20, 100 and 500 mg/kg/day, by gavage, on gestational days (GD) 6–19. Testosterone (T) levels of prepubertal rats diminished at high dose DHP and middle dose DCHP groups. MIS/AMH levels elevated in DHP and DCHP groups. T levels of pubertal rats decreased in low and high dose DHP and DCHP groups. Inhibin B levels of adult rats diminished in DCHP groups. Atrophic and amorphous tubules, spermatogenic cell debris, apoptotic cells, adherent tubules, Sertoli cell vacuolisation, prostatic atrophic tubules and prostatic intraepithelial neoplasia (PIN) were observed in the reproductive organs of treated animals at all developmental stages. There was an increase in immunoexpression of MIS/AMH in testes of treated rats. There were no changes in sperm head count but percentages of abnormal sperms increased. The diameters of seminiferous and epididymal tubules in treatment groups were significantly lower. This study shows that DHP and DCHP may have antiandrogenic effects on male reproductive development before and after birth.     

Non-linearities in the pharmacokinetics of di-(2-ethylhexyl) phthalate and metabolites in male rats

The disposition of the plasticizer di-(2-ethylhexyl) phthalate (DEHP) and four of its major metabolites was studied in male rats given single infusions of a DEHP emulsion in doses of 5, 50 or 500 mg DEHP/kg body weight. Plasma concentrations of DEHP and metabolites were followed for 24 h after the start of the infusion. The kinetics of the primary metabolite mono-(2-ethylhexyl) phthalate (MEHP) was studied separately.The concentrations of DEHP in plasma were at all times considerably higher than those of MEHP, and the concentrations of MEHP were much higher than those of the other investigated metabolites. In animals given 500 mg DEHP/kg, the areas under the plasma concentration-time curves (AUCs) of the other investigated metabolites were at most 15% of that of MEHP. Parallel decreases in the plasma concentrations of DEHP, MEHP and the and (-1) oxidized metabolites indicated that the elimination of DEHP was the rate-limiting step in the disposition of the metabolites. This was partly supported by the observation that the clearance of MEHP was higher than that of DEHP. Nonlinear increases in the AUCs of DEHP and MEHP indicated saturation in the formation as well as the elimination of the potentially toxic metabolite MEHP.     

Urinary metabolites of di-n-octyl phthalate in rats

Di-n-octyl phthalate (DnOP) is a plasticizer used in polyvinyl chloride plastics, cellulose esters, and polystyrene resins. The metabolism of DnOP results in the hydrolysis of one ester linkage to produce mono-n-octyl phthalate (MnOP), which subsequently metabolizes to form oxidative metabolites. We investigated the toxicokinetics of DnOP in adult female Sprague–Dawley rats by monitoring the excretion of DnOP metabolites in urine after oral administration of DnOP (300 mg/kg). By using authentic standards, the presence of urinary phthalic acid (PA), MnOP, and the major DnOP metabolite, mono-(3-carboxypropyl) phthalate (MCPP) was clearly established. Furthermore, we identified five additional urinary DnOP oxidative metabolites based on their chromatographic behavior and mass spectrometric fragmentation pattern. These DnOP oxidative metabolites, are postulated to be mono-carboxymethyl phthalate (MCMP), mono-(5-carboxy-n-pentyl) phthalate (MCPeP), mono-(7-carboxy-n-heptyl) phthalate (MCHpP), and isomers of mono-hydroxy-n-octyl phthalate (MHOP) (e.g., mono-(7-hydroxy-n-octyl) phthalate) and of mono-oxo-n-octyl phthalate (MOOP) (e.g., mono-(7-oxo-n-octyl) phthalate). The urinary excretion of DnOP metabolites followed a biphasic excretion pattern. The metabolite levels decreased significantly after the first day of DnOP administration although MCPP, MCHpP, MHOP, and MOOP were detectable after 4 days. We also studied the in vitro metabolism of DnOP and MnOP by rat liver microsomes. DnOP produced MnOP, MHOP, and PA in vitro whereas, MnOP produced MHOP and PA in vitro at detectable levels.