Gray L E, Ostby J, Furr J, Price M, Veeramachaneni D N, Parks L
Endocrinology Branch, MD 72, U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, Reproductive Toxicology Division, Research Triangle Park, North Carolina 27711, USA.
Toxicol Sci. 2000 Dec;58(2):350-65. doi: 10.1093/toxsci/58.2.350.
In mammals, exposure to antiandrogenic chemicals during sexual differentiation can produce malformations of the reproductive tract. Perinatal administration of AR antagonists like vinclozolin and procymidone or chemicals like di(2-ethylhexyl) phthalate (DEHP) that inhibit fetal testicular testosterone production demasculinize the males such that they display reduced anogenital distance (AGD), retained nipples, cleft phallus with hypospadias, undescended testes, a vaginal pouch, epididymal agenesis, and small to absent sex accessory glands as adults. In addition to DEHP, di-n-butyl (DBP) also has been shown to display antiandrogenic activity and induce malformations in male rats. In the current investigation, we examined several phthalate esters to determine if they altered sexual differentiation in an antiandrogenic manner. We hypothesized that the phthalate esters that altered testis function in the pubertal male rat would also alter testis function in the fetal male and produce malformations of androgen-dependent tissues. In this regard, we expected that benzyl butyl (BBP) and diethylhexyl (DEHP) phthalate would alter sexual differentiation, while dioctyl tere- (DOTP or DEHT), diethyl (DEP), and dimethyl (DMP) phthalate would not. We expected that the phthalate mixture diisononyl phthalate (DINP) would be weakly active due to the presence of some phthalates with a 6-7 ester group. DEHP, BBP, DINP, DEP, DMP, or DOTP were administered orally to the dam at 0.75 g/kg from gestational day (GD) 14 to postnatal day (PND) 3. None of the treatments induced overt maternal toxicity or reduced litter sizes. While only DEHP treatment reduced maternal weight gain during the entire dosing period by about 15 g, both DEHP and DINP reduced pregnancy weight gain to GD 21 by 24 g and 14 g, respectively. DEHP and BBP treatments reduced pup weight at birth (15%). Male (but not female) pups from the DEHP and BBP groups displayed shortened AGDs (about 30%) and reduced testis weights (about 35%). As infants, males in the DEHP, BBP, and DINP groups displayed femalelike areolas/nipples (87, 70, and 22% (p < 0.01), respectively, versus 0% in other groups). All three of the phthalate treatments that induced areolas also induced a significant incidence of reproductive malformations. The percentages of males with malformations were 82% (p < 0.0001) for DEHP, 84% (p < 0.0001) for BBP, and 7.7% (p < 0.04) in the DINP group. In summary, DEHP, BBP, and DINP all altered sexual differentiation, whereas DOTP, DEP, and DMP were ineffective at this dose. Whereas DEHP and BBP were of equivalent potency, DINP was about an order of magnitude less active.
在哺乳动物中，性分化期间接触抗雄激素化学物质会导致生殖道畸形。围产期给予抗雄激素受体拮抗剂如乙烯菌核利和腐霉利，或抑制胎儿睾丸睾酮生成的化学物质如邻苯二甲酸二（2-乙基己基）酯（DEHP），会使雄性动物去雄化，导致成年后它们的肛门生殖距（AGD）缩短、乳头保留、阴茎裂伴尿道下裂、睾丸未降、阴道袋、附睾发育不全以及性附属腺小或缺失。除DEHP外，邻苯二甲酸二正丁酯（DBP）也已被证明具有抗雄激素活性并能诱导雄性大鼠出现畸形。在本研究中，我们检测了几种邻苯二甲酸酯，以确定它们是否以抗雄激素方式改变性分化。我们假设，在青春期雄性大鼠中改变睾丸功能的邻苯二甲酸酯也会改变胎儿期雄性大鼠的睾丸功能，并导致雄激素依赖组织的畸形。在这方面，我们预期邻苯二甲酸苄基丁酯（BBP）和邻苯二甲酸二乙基己酯（DEHP）会改变性分化，而邻苯二甲酸二辛酯（DOTP或DEHT）、邻苯二甲酸二乙酯（DEP）和邻苯二甲酸二甲酯（DMP）则不会。我们预期邻苯二甲酸酯混合物邻苯二甲酸二异壬酯（DINP）由于存在一些带有6-7个酯基的邻苯二甲酸酯，活性较弱。从妊娠第14天（GD）至出生后第3天（PND），以0.75 g/kg的剂量给孕鼠口服DEHP、BBP、DINP、DEP、DMP或DOTP。所有处理均未引起明显的母体毒性或减少窝仔数。虽然只有DEHP处理在整个给药期间使母体体重增加减少了约15 g，但DEHP和DINP分别使妊娠至GD 21时的体重增加减少了24 g和14 g。DEHP和BBP处理使出生时幼仔体重减轻（15%）。来自DEHP和BBP组的雄性（而非雌性）幼仔AGD缩短（约30%），睾丸重量减轻（约35%）。作为幼崽，DEHP、BBP和DINP组的雄性出现类似雌性的乳晕/乳头（分别为87%、70%和22%（p < 0.01），而其他组为0%）。所有三种诱导乳晕出现的邻苯二甲酸酯处理也都导致了显著的生殖畸形发生率。DEHP组畸形雄性的百分比为82%（p < 0.0001），BBP组为84%（p < 0.0001），DINP组为7.7%（p < 0.04）。总之，DEHP、BBP和DINP均改变了性分化，而在此剂量下DOTP、DEP和DMP无效。虽然DEHP和BBP效力相当，但DINP的活性约低一个数量级。
