Evaluation of spermatogenesis and fertility in F1 male rats after in utero and neonatal exposure to extremely low frequency electromagnetic fields

Aim: To determine whether in utero and neonatal exposure to a 60Hz extremely low frequency electromagnetic field (EMF) results in spermatotoxicity and reproductive dysfunction in the F1 offspring of rats. Methods: Age-matched,pregnant Sprague-Dawley rats were exposed continuously (21h/day) to a 60 Hz EMF at field strengths of 0 (sham control), 5, 83.3 or 500 μT from day 6 of gestation through to day 21 of lactation. The experimentally generated magnetic field was monitored continuously (uninterrupted monitoring over the period of the study) throughout the study. Results: No exposure-related changes were found in exposed or sham-exposed animals with respect to the anogenital distance, preputial separation, testis weight, testicular histology, sperm count, daily sperm production,sperm motility, sperm morphology and reproductive capacity of F1 offspring. Conclusion: Exposure of Sprague-Dawley rats to a 60Hz EMF at field strengths of up to 500μT from day 6 of gestation to day 21 of lactation did not produce any detectable alterations in offspring spermatogenesis and fertility.     

DEHP与GEN孕期及哺乳期暴露对雄性子代成年大鼠生殖系统的影响

目的 探讨DEHP与GEN孕期及哺乳期暴露对雄性子代成年大鼠生殖系统发育的影响及其机制.方法 30只孕鼠于孕3 d（GD3）~子代出生后21 d（PND21）,每天按分组方案灌胃,观察对成年后（PND90）雄性子代生殖系统发育的影响.结果 孕期及哺乳期单一暴露于DEHP（250mg/kg）,精子密度及（a＋b）级活动率较对照组下降.单一暴露于GEN（400mg/kg）,脏器系数、精子质量、睾丸附睾组织学等较对照组无显著性变化.孕期及哺乳期同时暴露于DEHP（250 mg/kg）及低剂量GEN（50mg/kg）,精子质量、组织学表现较DEHP单一暴露明显改善.孕期及哺乳期同时暴露于DEHP（250 mg/kg）及高剂量GEN（400mg/kg）,睾丸系数、前列腺系数、精子质量、组织学改变较空白组及DEHP或GEN单一暴露损害明显加重.结论 DEHP单一暴露可导致精子质量下降,GEN单一暴露并未表现出明显生殖毒性,低剂量GEN对DEHP造成的损害具有一定的拮抗作用,高剂量GEN可加重 DEHP造成的损害.     

Effect of transient embryonic in vivo exposure to the endocrine disruptor methoxychlor on embryonic and postnatal testis development

The current study was designed to examine the effects of a transient embryonic exposure to the pesticide methoxychlor, an endocrine disruptor, on in vivo rat testis development and function. Gestating female rats were transiently administered methoxychlor (MXC) from embryonic day 7 (E7; EO = plug date) through E15. Embryonic testes were collected at E16 and postnatal (PO = day of birth) testes at P4, P10, P17-20, and P60. Seminiferous cords formed in testes from MXC exposed males. However, at E16, there was a decrease in the area of cords and an increase in interstitial area in MXC exposed testes when compared with controls. At all postnatal ages collected, there did not appear to be differences in seminiferous cord/tubule area, interstitial area, or number of seminiferous cords/tubules between untreated controls and males exposed to MXC. Exposure to the endocrine disruptor also had no effect on the postnatal organ weights of a variety of different organs, nor were testosterone levels altered. Interestingly, there were reductions in the number of germ cells in testes from MXC-exposed males at P17-P20 when compared with untreated controls. Furthermore, there was a twofold increase in apoptotic cells in tubules from pubertal P17-P20-MXC exposed males when compared with untreated controls. Testes were collected from adult P60 males to determine if early embryonic and postnatal alterations in germ cell numbers or testis cellular composition had compromised spermatogenesis. In adult P60 MXC exposed testes there were no gross morphological changes in testis structure or cellular composition over that of controls. However, there was an increase in apoptotic cell number in elongating spermatids in MXC exposed testes. Four P60 males that were exposed to MXC during gestation and 4 control males were bred with unexposed females to determine their ability to produce offspring. All MXC exposed males were capable of impregnating females and had normal litter size and pup weights. Combined observations demonstrated that exposure to MXC during gestation at a critical stage of testis development (ie, sex determination) affects embryonic testis cellular composition, germ cell numbers, and germ cell survival. While alterations in these parameters does not affect the ability of males to produce offspring, there appears to be a reduced spermatogenic capacity associated with MXC treatment. Therefore, transient embryonic exposure to an endocrine disruptor (methoxychlor) during gestation can influence the germline and fertility in adult males.     

新生期甲醛染毒对成年后大鼠雄性性行为、睾丸重量以及血清睾酮水平的影响

目的观察新生期甲醛染毒对成年后大鼠雄性性行为、睾丸重量和血清睾酮水平的影响。方法选用健康清洁级新生7日龄雄性SD大鼠24只,随机分为高剂量甲醛（10mg/m3）、低剂量甲醛（0.1mg/m3）染毒组和对照组3组,甲醛染毒14d后常规饲养4周至成年。然后分别观察成年后雄性大鼠的扑捉潜伏期（CLP）和60min内扑捉雌鼠的次数（CT）,称量睾丸重量以及利用放免法测定大鼠血清睾酮（T）水平。结果低剂量甲醛染毒组大鼠CLP,CT,睾丸重量以及血清睾酮含量与对照组相比没有明显差异。但高剂量甲醛染毒组大鼠的扑捉潜伏期（CLP）与对照组相比明显升高（P〈0.05）;60min内扑捉雌鼠的次数（CT）、睾丸重量与对照组相比均明显下降（P〈0.05）;大鼠血清睾酮水平与对照组和低剂量甲醛染毒组相比轻度下降。结论新生期甲醛染毒对成年后雄性大鼠性行为以及睾丸有一定的损伤作用,并且损伤具有剂量依赖性。     

Abolition of prenatal lipopolysaccharide‐induced reproductive disorders in rat male offspring by fulvestrant

During prenatal and early postnatal periods of development, multiple environmental factors have profound and long‐lasting effects on the immune and reproductive functions. The aim of this study was to investigate the effects of maternal lipopolysaccharide (LPS) exposure (50 mg/kg, i.p.) at day 12 of pregnancy and estradiol antagonist treatment (fulvestrant, 1.5 mg/kg, s.c. in neck) at postnatal days 5–14 (PND5–14) with high estradiol levels on reproductive parameters in adult rat males. Serum steroid concentrations were measured in male offspring at PND80 by ELISA. Body, testis weights and ano‐genital distance (AGD) were recorded at different stages of postnatal development. Testis was also processed to cytohistological studies at PND80. Our results demonstrate that body weight was decreased from PND14 to 30 after prenatal LPS treatment and was increased after fulvestrant treatment. AGD was decreased after prenatal LPS treatment and was increased after fulvestrant injections. Testis weight, testosterone level, seminiferous tubule diameter, and number of Sertoli and spermatid cells were also decreased in rats exposed prenatally to LPS and were restored to the normal control level after fulvestrant treatment. According to results, we can conclude that the development of sexual disorders in males after prenatal immune stress is potentiated by estradiol during the pre‐pubertal period.     

The effects of maternal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on testicular steroidogenesis in infantile male rats

Exposure of adult male animals to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) decreases serum androgen concentrations. Reduction in androgen levels after maternal exposure has also been reported, but these results have not been reproduced. We have earlier shown that TCDD stimulates rather than inhibits testosterone synthesis in the prenatal rat testis. The aim of the present study was to elucidate in utero-induced effects of TCDD on testicular steroidogenesis in the 14-day-old infant rats. At that time the foetal Leydig cell population is still the prevailing source of androgens. Pregnant Sprague-Dawley dams were given a single oral dose of TCDD (0, 0.04, 0.2, or 1.0 microg/kg) on day 13 of pregnancy. On postnatal day 14, the body weight of male offspring was reduced after exposure to 1.0 microg/kg TCDD (from 33.9 +/- 1.66 g to 31.6 +/- 2.67 g). Relative testis weight, plasma testosterone, luteinizing hormone and follicle-stimulating hormone levels remained unaltered in all exposure groups. Moreover, in ex vivo incubations, testosterone and cAMP production was not affected. StAR protein level in the freshly isolated testes was increased in the 0.2 microg/kg group, and seminiferous cord diameter in the 0.04 microg/kg group. The present study confirms our earlier findings in in utero TCDD-exposed foetal testis indicating that maternal TCDD exposure does not negatively influence the developmental testosterone production of foetal type Leydig cells in rats.     

Maternal cannabinoid exposure Effects on spermatogenesis in male offspring

Maternal exposure to cannabinoids influenced spermatogenesis and fertility in their male offspring examined at 60-80 days of age. Approximately 20% less spermatozoa were found in males whose mothers had received either the non-psychoactive cannabinol (CBN) or cannabidiol (CBD) on day 1 postpartum. Males exposed to the major psychoactive component of marihuana, delta 9-tetrahydrocannabinol (THC) appeared to have spermatozoa in number comparable to controls. This finding may be consistent with the additional observation that CBN or CBD, but not THC, reduced the percentage of successful impregnations by cannabinoid-exposed males. However, males exposed to each of these cannabinoids produced significantly less live offspring compared to controls. Plasma levels of testosterone and luteinizing hormone (LH) were reduced significantly in mice exposed to THC on day 12 of gestation, while testicular weight was reduced in adult mice exposed either on day 12 of gestation to CBD or on day 1 post-partum to THC. These results indicate that perinatal exposure to psychoactive and non-psychoactive components of marihuana can produce long-term disruption of testicular function including the spermatogenic as well as the steroidogenic components.     

Effect of honey on the reproductive system of male rat offspring exposed to prenatal restraint stress

Exposure to prenatal stress is associated with impaired reproductive function in male rat offspring. Honey is traditionally used by the Malays for enhancement of fertility. The aim of this study was to determine the effect of honey on reproductive system of male rat offspring exposed to prenatal restraint stress. Dams were divided into four groups (n = 10/group): control, honey, stress and honey + stress groups. Dams from honey and honey + stress groups received oral honey (1.2 g kg^?1 body weight) daily from day 1 of pregnancy, meanwhile dams from stress and honey + stress groups were subjected to restraint stress (three times per day) from day 11 of pregnancy until delivery. At 10 weeks old, each male rat offspring was mated with a regular oestrus cycle female. Male sexual behaviour and reproductive performance were evaluated. Then, male rats were euthanised for assessment on reproductive parameters. Honey supplementation during prenatal restraint stress significantly increased testis and epididymis weights as well as improved the percentages of abnormal spermatozoa and sperm motility in male rat offspring. In conclusion, this study might suggest that supplementation of honey during pregnancy seems to reduce the adverse effects of restraint stress on reproductive organs weight and sperm parameters in male rat offspring.     

The effect of dihydrotestosterone exposure during or prior to the masculinization programming window on reproductive development in male and female rats

Masculinization is programmed by androgen exposure during a masculinization programming window (MPW). Deficiency in MPW androgen action results in reduced size of all reproductive organs and anogenital distance (AGD) and reproductive disorders. Although timing of MPW closing has been defined, what determines 'opening' and 'closing' of the MPW remains unknown. To test whether initiation of testosterone production/action defines the opening of the window, we first demonstrated that androgen receptor mRNA and protein are expressed prior to the MPW, and then investigated whether masculinization could be advanced or enhanced by treating pregnant rats with either 1 or 10 mg/kg/day dihydrotestosterone (DHT) prior to (early window, EW; e11.5-e14.5) or during the MPW (e15.5-e18.5), and then evaluating offspring in foetal life (e18.5, e21.5), early puberty (day 25) or adulthood (～day 75). DHT treatment did not affect pregnancy duration, birth, litter or pup size. DHT exposure in either time window did not advance foetal male development (Wolffian duct coiling) and had no effect on AGD, testis, penis and ventral prostate (VP) size at any age when measured; there was a tendency towards smaller penis size. In contrast, exposure of females to 10 mg DHT in either time window induced varying degrees of masculinization, including stabilization of the Wolffian duct and increased AGD (e21.5, Pnd25), VP formation, more male-like phallus structure, absence of nipples and vaginal opening and, in some adult females, gross fluid distension of the uterus (hydrometrocolpos); these effects were generally more pronounced after exposure in the MPW than in the EW. In conclusion, exposure of the male rat foetus to additional androgens prior to or during the MPW does not advance or enhance any measured parameter of reproductive development. Therefore, androgen availability plays no role in determining timing of the MPW. Susceptibility of the female reproductive system to androgens may precede the MPW.     

Coadministration of active phthalates results in disruption of foetal testicular function in rats

The reproductive effects of the coadministration of di-2-(ethylhexyl) phthalate (DEHP) and di-butyl phthalate (DBP) were studied in both foetal and adult male rat offspring exposed in utero . Pregnant Wistar rats were treated by oral gavage from gestation day 13 to 21 with vehicle control, 150 mg DEHP/kg body weight (bw)/day, 100 mg DBP/kg bw/ or a combination of the two compounds (DEHP 150 + DBP 100 mg/kg bw/day). An additional group of dams received 500 mg DBP/kg bw/day. A significant decrease in foetal testicular testosterone levels was observed in animals exposed to 500 mg DBP/kg/day or the phthalate mixture. Similarly, histological analysis of the foetal testis revealed that the coadministration of DEHP and DBP was able to increase the diameter of seminiferous cords and induce gonocyte multinucleation at doses that individually had no significant effects on these variables. However, in the phthalate mixture group, no significant changes were observed in anogenital distance and nipple retention, variables that are used to indicate possible anti-androgenic effects. Also, the adult endpoints investigated, that included reproductive organ weights and the number of spermatids per testis, were unaffected by any treatment regimen. Overall, coadministration of DEHP and DBP in utero significantly reduced testicular testosterone levels and resulted in misshapen seminiferous cords and gonocyte multinucleation in rat foetal testis. Our results also confirm that these foetal endpoints seem to be the most sensitive markers of prenatal phthalate exposure.     

Testicular tumors in mice exposed in utero to diethylstilbestrol

Treatment of pregnant women with diethylstilbestrol (DES) is associated with the subsequent development of reproductive tract abnormalities such as epididymal cysts, retained hypotrophic testes and sperm abnormalities in their male offspring. It recently has been suggested that prenatal DES exposure is associated with development of testicular seminoma in humans. Studies of in utero exposure of laboratory animals to DES are few, but previous reports from our laboratory have described several abnormalities in the reproductive tract of the mouse following prenatal DES exposure. To study the possible association of testicular tumors and prenatal DES exposure in mice, pregnant outbred CD-1 mice were injected subcutaneously with daily doses of DES (100 micrograms./kg.) on days nine through 16 of gestation. DES-exposed and age-matched control male mice were sacrificed at 10 to 18 months of age and examined for testicular lesions. In addition to the nonmalignant abnormalities reported in previous studies such as 91% cryptorchidism and degenerative changes, interstitial cell tumors were observed in nine mice among 277 mice treated prenatally with DES. Two of these lesions were benign tumors and five were interstitial cell carcinomas. Rete testis adenocarcinoma was seen also in 5% of these DES-treated animals and is described in another report. The overall incidence of testicular tumors is 8% in DES-exposed male mice. No comparable lesions were seen in 122 control male mice. These results suggest that the testicular lesions that can occur following prenatal DES exposure include neoplasia. The combined prevalence of DES-induced tumors of the corpus testis and rete testis in mice suggests the male offspring may be more at risk for developing carcinoma of the reproductive tract than the female offspring.     

Effects of perfluorooctanoic acid exposure during pregnancy on the reproduction and development of male offspring mice

This study was conducted to explore the effects of maternal exposure to perfluorooctanoic acid (PFOA) on reproduction and development of male offspring mice. Pregnant mice were given 1, 2.5 or 5 mg/kg BW PFOA daily by gavage during gestation. The results showed that the survival number of offspring mice at weaning was significantly decreased. There were no differences in the testicular index of offspring mice between PFOA exposure groups and non‐PFOA group. Maternal exposure to PFOA reduced the level of testosterone in the male offspring mice on PND 21 (p < 0.01) but increased in 1 mg/kg group and decreased in 2.5 and 5 mg/kg groups on PND 70 (p < 0.01). There were different degrees of damage to testis in a dose‐dependent manner, and the number of Leydig cells markedly decreased (p < 0.01) in 2.5 and 5 mg/kg PFOA groups on PND 21 and PND 70. The expression of Dlk1‐Dio3 imprinted gene cluster showed a decreasing trend, where Glt2, Rian and Dio3 gene expressions were significantly reduced (p < 0.05) on PND 21. Therefore, PFOA exposure during pregnancy reduces the number of survival offspring mice, damages testis, disrupts reproductive hormones and reduces the mRNA expressions of the Dlk1‐Dio3 imprinted cluster in testis.     

大豆异黄酮对不同时期子代雄性大鼠生殖性状及ER-β受体表达的影响

目的:研究大豆异黄酮孕期和出生后暴露对子代雄性大鼠生殖系统发育相关指标以及ER-β受体表达的影响。方法:SD大鼠随机分为对照组(玉米油)、大豆异黄酮50、200、400 mg/kg体重和已烯雌酚(DES)0.1 mg/kg体重组,母鼠从妊娠0 d开始灌胃各组药品,子鼠21 d断奶后开始灌胃直至处死。子代雄性大鼠每组随机取6只分别在49 d、90 d处死,观察生殖系统发育相关指标并检测睾丸组织ER-β受体表达情况。结果:①对于不同年龄段子代雄鼠,大豆异黄酮各剂量组以及DES组每日平均摄食量均无显著性差异,但49～90日龄子鼠大豆异黄酮200 mg/kg体重、400 mg/kg体重组以及0.1 mg/kg体重DES组的食物利用率显著下降。②大豆异黄酮剂量为50 mg/kg体重以上时,不同年龄段的子鼠体重均显著下降(P<0.05)且90日龄子代雄鼠体重变化大于49日龄子代雄鼠。③随着大豆异黄酮剂量的增加,睾丸重量、睾丸精子头计数和每日精子生成量呈显著下降趋势且90日龄子鼠以上指标的变化比49日龄子代雄鼠变化更加明显。④随着大豆异黄酮剂量的增加,不同年龄段子代雄鼠各剂量组ER-β受体表达与对照组比较均呈上升趋势且90日龄子代雄鼠上升趋势大于49日龄子代雄鼠。结论:大豆异黄酮孕期和出生后暴露可干扰子鼠雄性生殖系统的发育,ER-β受体表达变化可能是其机制之一。     

Prenatal exposure to dexamethasone alters Leydig cell steroidogenic capacity in immature and adult rats.

This study examines the effects of prenatal exposure to dexamethasone (DEX) on postnatal testosterone production in male rats. Pregnant female rats were treated on gestation days 14-19 with DEX (100 microg/kg body weight per day; n = 9) or vehicle (n = 9). Results show that 35-day-old male offspring from DEX-treated pregnant females (n = 42) had decreased levels of serum testosterone (45.6% lower, P < .05) compared with control offspring (n = 43), although serum luteinizing hormone (LH) levels were not significantly altered. These findings suggest that a direct programming of developing gonadal cells occurs in response to high levels of maternal glucocorticoid. Indeed, testosterone production was significantly reduced in Leydig cells isolated from immature offspring of DEX-treated pregnant females compared with controls (48.3%, P < .001), and LH stimulation of these cells did not compensate for the lowered steroidogenic capacity. The hypothalamic-pituitary-adrenal axis was also affected, because significant reductions in both serum adrenocorticotropic hormone (ACTH; 26.2%, P < .001) and corticosterone (CORT; 32.3%, P < .001) were measured in DEX-exposed immature male offspring. In contrast, adult male offspring from DEX-treated dams had significantly higher levels of serum ACTH (39.2%, P <. 001) and CORT (37.8%, P < .001). These same animals had higher serum testosterone (31.6%, P < or = .05) and a significant reduction in serum LH (30.8%, P < .001). Moreover, Leydig cells isolated from these adult offspring exhibited an increased capacity for testosterone biosynthesis under basal (38.6%, P < .001) and LH-stimulated conditions (33.5%, P < .001). In summary, sustained changes in steroidogenic capacity were observed in male rats exposed to high levels of glucocorticoid during prenatal development. More specifically, DEX exposure in utero perturbed Leydig cell testosterone production in both pubertal and adult rats.     

邻苯二甲酸二(2-乙己基)酯致小鼠睾丸基因组DNA甲基化水平变化分析

目的:探讨增塑剂邻苯二甲酸二(2-乙己基)酯(DEHP)作用于怀孕小鼠后,其仔代睾丸基因组DNA甲基化水平的改变情况。方法:妊娠KM小鼠随机分为3组:正常对照组、玉米油对照组和DEHP实验组。自妊娠12.5 d到生后第3天分别持续经口予以玉米油和DEHP[500 mg/(kg.d)],于生后第7天取仔代睾丸,应用甲基敏感扩增多态性(MSAP)技术,对仔鼠睾丸组织DNA进行EcoRⅠ/MspⅠ和EcoRⅠ/HpaⅡ两种酶切反应,经ABI 3730DNA自动测序仪电泳及检测后,运用Genescan3.1分析扩增谱带。结果:对CCGG位点,DEHP实验组小鼠仔代睾丸组织DNA甲基化程度明显增高,其甲基化水平为(34.03±3.05)%;而正常对照组和玉米油对照组小鼠仔代睾丸组织基因组DNA甲基化程度分别为(28.37±2.37)%和(28.58±2.45)%。DEHP实验组与正常对照组和玉米油对照组相比,差异具有统计学意义(P<0.05)。结论:DEHP作用孕鼠后可导致仔代睾丸基因组DNA甲基化水平改变,影响基因组表观遗传修饰改变,可能是导致生殖系统损害的重要毒理机制之一。     

The role of a clinical score in the assessment of ambiguous genitalia

OBJECTIVE: To improve the initial assessment of ambiguous genitalia in infants. SUBJECTS AND METHODS: Using a specially devised scoring system, the external genitalia (external masculinization score, EMS, range 0-12) and internal reproductive structures (internal masculinization score, IMS, range 0-10) were assessed in 426 male newborns and 291 cases of ambiguous genitalia. RESULTS: In normal male newborns, the median (10th centile) EMS was 11 (10). In the affected infants, the sex of rearing was male in 202 and female in 89 cases, respectively. The median (10-90th centile) EMS in those cases reared male, at 3.5 (2-8), was significantly higher than in cases reared as females, at 2 (1-6) (P < 0.001). The median IMS in cases reared as males and females was the same, at 10, but the scatter of values was higher for males (10-90th centile, 4-10) than for females (0-10) (P = 0.01). Infants reared as females were more likely to have a micropenis, a uterus and/or a urogenital sinus, but there were 12 cases where the sex of rearing was male despite the presence of a uterus; five infants without micropenis were reared as female and 23 with a urogenital sinus were reared as male. CONCLUSION: The masculinization score provides a standardized format to summarize clinical features in newborn infants with ambiguous genitalia. Gender assignment does not solely depend on the appearance of the external genitalia and the nature of internal sexual organs.     

邻苯二甲酸二-(2-乙基)己酯致小鼠隐睾睾丸和附睾的组织病理学改变

目的 :探讨邻苯二甲酸二 (2 乙基 )己酯 (DEHP)引起的小鼠隐睾睾丸和附睾的组织病理学改变。　方法 :妊娠KM小鼠 4 0只 ,随机分成 5组 ,分别为正常对照组 8只、玉米油对照组 8只、己烯雌酚 (DES)组 8只、DEHP低剂量组 [DEHP 10 0mg/ (kg·d) ]9只和DEHP高剂量组 [DEHP 5 0 0mg/ (kg·d) ]7只。自妊娠第 12d开始到分娩后 3d ,分别持续经口给予DEHP 10 0mg/ (kg·d)、5 0 0mg/ (kg·d)和DES 10 0 μg/ (kg·d)及玉米油 ,观察仔代雄小鼠的隐睾发生率及隐睾睾丸和附睾的组织病理学改变。　结果 :DEHP 5 0 0mg/ (kg·d)组染毒小鼠的隐睾发生率显著增高 ,睾丸和附睾的体积明显减小、重量减轻 ;睾丸生精上皮发育明显异常 ,精曲小管变薄、萎缩 ,间质细胞异常增生 ,电镜下其隐睾精曲小管上皮和间质细胞均出现明显的超微结构改变。同时附睾管腔中的精子数显著减少甚至缺乏。　结论 :高剂量 [5 0 0mg/ (kg·d) ]DEHP可能具有与DES类似的作用 ,是一种诱发隐睾的重要因子。小鼠在孕期及哺乳期接触DEHP后可引起雄性仔鼠性分化异常 ,诱导隐睾发生、睾丸生精上皮损害和生精过程障碍 ,从而对雄性仔鼠生育力产生不利影响。以上作用存在明确的量 效关系。     

Gestational exposure to atrazine: effects on the postnatal development of male offspring

Atrazine is an herbicide used worldwide to control grasses and weeds. Previous studies have shown that, depending on atrazine's administered dose, exposure of male rats during the early postnatal or peripubertal periods can result in alterations in endocrine function. The gestational period is particularly vulnerable to environmental agents; however, the possible effects of atrazine exposure during this period have received only limited attention. Herein we examine the dose effects of atrazine exposure during Sprague-Dawley rat gestation on the postnatal development of male offspring. Pregnant dams were treated by oral gavage with atrazine at 0 to 100 mg/kg/d from gestational day 14 to parturition. Thereafter, neither the pups nor the dams received atrazine. Atrazine had no effect on the number of live births per dam. Neonatal pup survival was affected, however, with increased pup death seen at doses of 10 mg/kg/d and higher. There was no effect of atrazine on the testosterone concentration within the testes of newborn pups. Anogenital distance, an androgen-dependent process, decreased from the control level at the 75 and 100 mg/kg/d doses, with the decrease reaching significance at 100 mg/kg/d. Preputial separation, also an androgen-dependent process, was delayed significantly compared with that in controls in response to the 50 and 100 mg/kg/d doses. At postnatal day 60, serum testosterone concentrations were reduced significantly from controls in the 50 to 100 mg/kg/d groups. However, these decreases had little effect on seminal vesicle or ventral prostate weights. These results, taken together, are suggestive of antiandrogenic effects of gestational atrazine exposure on male offspring, although for most parameters, the doses used in this study are unlikely to be experienced under any but experimental conditions.     

Induction and persistence of abnormal testicular germ cells following gestational exposure to di-(n-butyl) phthalate in p53-null mice

Phthalate esters are commonly used plasticizers found in many household items, personal care products, and medical devices. Animal studies have shown that in utero exposure to di-(n-butyl) phthalate (DBP) within a critical window during gestation causes male reproductive tract abnormalities resembling testicular dysgenesis syndrome. Our studies utilized p53-deficient mice for their ability to display greater resistance to apoptosis during development. This model was chosen to determine whether multinucleated germ cells (MNG) induced by gestational DBP exposure could survive postnatally and evolve into testicular germ cell cancer. Pregnant dams were exposed to DBP (500 mg/kg/day) by oral gavage from gestational day 12 until birth. Perinatal effects were assessed on gestational day 19 and postnatal days 1, 4, 7, and 10 for the number of MNGs present in control and DBP-treated p53-heterozygous and null animals. As expected, DBP exposure induced MNGs, with greater numbers found in p53-null mice. Additionally, there was a time-dependent decrease in the incidence of MNGs during the early postnatal period. Histologic examination of adult mice exposed in utero to DBP revealed persistence of abnormal germ cells only in DBP-treated p53-null mice, not in p53-heterozygous or wild-type mice. Immunohistochemical staining of perinatal MNGs and adult abnormal germ cells was negative for both octamer-binding protein 3/4 and placental alkaline phosphatase. This unique model identified a role for p53 in the perinatal apoptosis of DBP-induced MNGs and provided insight into the long-term effects of gestational DBP exposure within a p53-null environment.