Reproductive effects of endosulfan on male offspring of rats exposed during pregnancy and lactation.

1. The reproductive effects of endosulfan on the male offspring of rats were examined. Dams were treated orally with 0, 1.5 or 3.0 mg endosulfan/kg from day 15 of pregnancy to postnatal day (PND) 21 of lactation. The male offspring rats were investigated at PND 65 or 140, corresponding to the pubertal and adulthood stage of development. 2. The dose of 3.0 mg endosulfan/kg induced a decrease in maternal body weight during pregnancy, but litter size and mean birth weight were not affected. Similarly, the age at testis descent and preputial separation was not affected on the male offspring. 3. The daily sperm production (x10(6)) was permanently decreased in the highest dose group when investigated at puberty and at adulthood. At the lowest dose, however, the daily sperm production was significantly reduced only at puberty. 4. Histologically, the percentage of seminiferous tubules showing complete spermatogenesis was significantly decreased at puberty. This finding may explain the decrease in daily sperm production observed in the endosulfan-exposed male rats. 5. The results of this study show that low doses of endosulfan have no apparent effect on developmental landmarks or on the weight of reproductive and accessory sex organ. Daily sperm production was the most susceptible endpoint in the male offspring exposed to endosulfan during pregnancy and lactation. To further understand the reproductive effects of endosulfan on male rat offspring, additional reproductive and toxicokinetic studies should be carried out to determine the extent of endosulfan exposure in male rat offspring in utero and during lactation.     

Effects of prenatal testosterone propionate on the sexual development of male and female rats: a dose-response study.

Testosterone plays a major role in male sexual development. Exposure of females to testosterone in utero can induce masculine characteristics such as anovulation, increased anogenital distance (AGD), absence of nipples, retention of male-like tissues, and agenesis of the lower vagina. In addition, high levels of androgens during fetal development can lead to toxic effects such as reduced litter size and viability. The study of the effects of testosterone administration during sexual differentiation provides a foundation for understanding the effects of environmental androgens on fetuses, a sensitive subpopulation. In the current study, we investigated the ability of a range of concentrations of testosterone propionate (TP) administered prenatally to masculinize female and alter male offspring, and measured maternal and fetal T levels. Pregnant Sprague-Dawley rats were dosed by sc injection on gestational day (GD) 14-19 (GD 1= day of plug) with either corn oil (vehicle; 0.1 ml/rat) or with 0.1 ml of TP solution at 0.1, 0.5, 1, 2, 5, or 10 mg/0.1 ml. Parturition was delayed at 2, 5, and 10 mg TP, litter size was reduced at 5 and 10 mg TP, and pup weight was significantly reduced in both sexes at 0.5 mg TP and higher doses. Viability of offspring was unaffected at any dosage level. Androgenic effects seen at 0.5 mg TP in females included increased AGD at weaning and adulthood, reduced number of areolas and nipples, cleft phallus, small vaginal orifice, and presence of prostate tissue. This dose of TP elevated maternal T levels 10x but had no effect on fetal T levels. At 1 mg TP and above, female AGD on postnatal day (PND) 2 (or postcoital day 24 [gestation length = 22(1/2)]) was increased; areolas and nipples were virtually eliminated; levator ani muscle, bulbourethral glands, and seminal vesicles (2 mg TP and above) were present; none of the females developed a vaginal orifice and many females in the 1 and 2 mg TP dose groups developed a greatly distended, fluid-filled uterus after puberty. Maternal T levels at 1 mg TP were elevated 30x, and female fetal T levels showed an 80% increase. Male offspring displayed a reduced AGD and body weight on PND 2 at 0.5 mg TP and higher doses. These effects were not evident by weaning and male offspring displayed no malformations. We conclude that gestational administration of 0.5 and 1 mg TP masculinizes female offspring without greatly affecting pup viability or pregnancy of the dam. This study provides a useful model for in utero testing of environmental androgens for their potential to induce developmental abnormalities.     

Prenatal testosterone exposure permanently masculinizes anogenital distance, nipple development, and reproductive tract morphology in female Sprague-Dawley rats.

In mammals, abnormal increases in fetal androgens disrupt normal development of the female phenotype. Due to the recent concern regarding environmental androgen-active chemicals, there is a need to identify sources of fetal androgen variation and sensitive developmental markers for androgenic activity in female rats. Anogenital distances (AGD), nipple retention, reproductive tract, and external genitalia are morphological parameters organized by prenatal androgens and are predictive of altered masculinized/defeminized phenotype in adult female mice and rats. The objectives of this study were to (1) characterize the natural prenatal androgen environment of rats including the magnitude of the intrauterine position (IUP) effect, (2) characterize the permanent effects of prenatal androgen exposure on female rats, and (3) determine the ability of AGD and areolas to predict these permanent androgenic alterations in female rats. Untreated male fetal rats had higher tissue testosterone (T) concentrations than females in the amniotic fluid, reproductive tract, gonad, and fetal body. The intrauterine position (IUP) of male and female fetuses did not affect T concentrations or AGD in male or female rats at gestational day (GD) 22. Female offspring exposed to 0, 1.5, and 2.5 mg/kg/day testosterone propionate (TP) on GDs 14-18 displayed increased AGD at postnatal day (PND) 2 and decreased nipples at PND 13 and as adults. TP-induced changes in neonatal AGD and infant areola number were reliable indicators of permanently altered adult phenotype in female rats. Further, females in the two high-dose groups displayed increased incidences of external genital malformations and the presence of prostatic tissue, not normally found in female rats.     

Androgen-mediated development in male rat offspring exposed to flutamide in utero: permanence and correlation of early postnatal changes in anogenital distance and nipple retention with malformations in androgen-dependent tissues.

Male offspring exposed in utero to antiandrogens often display alterations in androgen-dependent developmental markers (e.g., anogenital distance [AGD], nipple retention) together with clearly adverse responses such as genital malformations and reproductive tract lesions. The objectives of this study were to determine whether in utero exposure to flutamide results in permanent changes in male AGD and nipple retention, characterize the dose-response relationship between flutamide-mediated alterations in these landmarks and clearly adverse antiandrogenic effects, and establish the predictive value and relationship between AGD and nipple retention, and other adverse manifestations. Male offspring were exposed in utero to 0, 6.25, 12.5, 25, or 50 mg/kg/day (po) of flutamide from gestation days 12 to 21. Offspring were uniquely identified at birth, and various androgen-mediated end points (AGD, areola/nipple retention, cryptorchidism, reproductive tract weights, and malformation incidence) were examined throughout life. In utero flutamide exposure significantly decreased the AGD on postnatal day (PND) 1 and increased areola/nipple retention in male rats on PND 13. Flutamide-induced alterations in AGD and areolae/nipples in early postnatal life correlated with a reduction in AGD and retained nipples observed in the adult. Prenatal flutamide exposure resulted in dose-responsive increases in cryptorchidism. Hypospadias were observed in all flutamide-exposed offspring. In utero flutamide exposure induced partial or complete prostate agenesis and decreased the weights of the seminal vesicles, levator ani bulbocavernosus (LABC) muscle, testes, and epididymides in a dose-dependent manner. Epididymal malformations were observed mainly in the 50 mg/kg/day flutamide dose group. In general, flutamide-induced alterations in dihydrotestosterone (DHT)- and testosterone (T)-dependent development each had similar respective dose-response curves. DHT-mediated development was more sensitive to in utero flutamide exposure than T-dependent processes. However, the dose-response curves for flutamide-induced changes in cryptorchidism and seminal vesicle weight were intermediate between the dose-response curves for DHT- and T-mediated development, indicating that proper development of these tissues may require both androgens. The LABC also displayed a dose-dependent decrease in weight that was similar to dose-response observed with seminal vesicle weight and was the most sensitive T-dependent end point measured. Flutamide-induced decreases in AGD predicted subsequent malformations as evidenced by logistic regression and receiver operator characteristic analysis of malformations versus AGD. However, the AGD that would predict a 10% incidence of seminal vesicle malformations is equivalent to a female AGD. An almost fully feminized phenotype of 10-12 nipples was observed in animals that had malformations in T-dependent tissues, whereas 6 or more nipples were observed in animals with malformation in DHT-dependent tissues. These data suggest that flutamide-mediated changes in AGD and nipple retention are not sensitive predictors of altered T-mediated development.     

Pre- and postnatal toxicity of the commercial glyphosate formulation in Wistar rats

Glyphosate is the active ingredient and polyoxyethyleneamine is the surfactant present in the herbicide Roundup formulation commercialized in Brazil. The aim of this study was to assess the reproductive effects of glyphosate-Roundup on male and female offspring of Wistar rats exposed during pregnancy and lactation. Dams were treated orally with water or 50, 150 or 450 mg/kg glyphosate during pregnancy (21-23 days) and lactation (21 days). These doses do not correspond to human exposure levels. The results showed that glyphosate-Roundup did not induce maternal toxicity but induced adverse reproductive effects on male offspring rats: a decrease in sperm number per epididymis tail and in daily sperm production during adulthood, an increase in the percentage of abnormal sperms and a dose-related decrease in the serum testosterone level at puberty, and signs of individual spermatid degeneration during both periods. There was only a vaginal canal-opening delay in the exposed female offspring. These findings suggest that in utero and lactational exposure to glyphosate-Roundup may induce significant adverse effects on the reproductive system of male Wistar rats at puberty and during adulthood.     

Reproductive toxicity evaluation of dietary butyl benzyl phthalate (BBP) in rats

Butyl benzyl phthalate (BBP) was administered in the diet at 0, 750, 3750, and 11,250 ppm ad libitum to 30 rats per sex per dose for two offspring generations, one litter/breeding pair/generation, through weaning of F2 litters. Adult F0 systemic toxicity and adult F1 systemic and reproductive toxicity were present at 11,250 ppm (750 mg/kg per day). At 11,250 ppm, there were reduced F1 and F2 male anogenital distance (AGD) and body weights/litter during lactation, delayed acquisition of puberty in F1 males and females, retention of nipples and areolae in F1 and F2 males, and male reproductive system malformations. At 3750 ppm (250 mg/kg per day), only reduced F1 and F2 offspring male AGD was present. There were no effects on parents or offspring at 750 ppm (50 mg/kg per day). The F1 parental systemic and reproductive toxicity no observable adverse effect level (NOAEL) was 3750 ppm. The offspring toxicity NOAEL was 3750 ppm. The offspring toxicity no observable effect level (NOEL) was 750 ppm, based on the presence of reduced AGD in F1 and F2 males at birth at 3750 ppm, but no effects on reproductive development, structures, or functions.     

Pre and postnatal exposure to endosulfan in Wistar rats

The possible reproductive adverse effects of the pesticide endosulfan on male offspring rats exposed in utero and during lactation were investigated. Dams were treated orally with 0, 0.5 or 1.5 mg of endosulfan/kg 21 days prior to mating, during the mating, pregnancy and lactation. Maternal and reproductive outcome data and male sexual development landmarks (testis descent and preputial separation) were assessed. Reproductive endpoints of the male offspring were examined at adulthood: sex organ weights, daily sperm production, spermatid number, sperm transit, sperm morphology and testosterone level. No signs of maternal toxicity were detected at the dose levels tested. Sexual development landmarks were also unaffected. Moreover, with the exception of a significant increase in the relative epididymis weight seen in the group treated with the lowest dose, we have not found any statistically significant adverse effect in the reproductive endpoints investigated at adulthood. The results of the present study indicate that pre and postnatal exposure to low doses of endosulfan (0.5 and 1.5 mg/kg) do not induce significant adverse effects in the reproductive system of male offspring Wistar rats at adulthood.     

Effects of perinatal ethinyl estradiol exposure in male and female Wistar rats

Perinatal exposure to endocrine disrupting chemicals with estrogenic activity can adversely affect reproductive development, but few studies evaluating estrogen-sensitive endpoints have been performed in Wistar rats. Therefore, time-mated Wistar rats (n = 10) were gavaged during gestation and lactation with 0, 5, 15 or 50 μg/kg bw/day of ethinyl estradiol.This potent estrogen was found to induce an increased number of nipples and reduced ovary weight in female offspring. Malformations of female genitalia were found in young as well as adult offspring, as an increased AGD was seen at birth and a deeper urethral slit length was seen in adulthood. In prepubertal male offspring, estrogen-regulated gene expression in ventral prostate was increased dose-dependently and a decreased ventral prostate weight was seen at 15 μg/kg.Female external sexual characteristics and prostate development were found to be targets for exposure to estrogenic compounds and may be of interest in studies on estrogenic environmental compounds.     

Effects of in utero exposure to finasteride on androgen-dependent reproductive development in the male rat.

Finasteride is a specific inhibitor of type II 5alpha-reductase, the enzyme that converts testosterone (T) to the more potent androgen receptor agonist dihydrotestosterone (DHT). In utero exposure to androgen receptor antagonists and T biosynthesis inhibitors have induced permanent effects on androgen-sensitive end points such as anogenital distance (AGD), nipple retention, and malformations of the male rat reproductive tract. The objectives of this study were to (1) characterize the dose response of finasteride-mediated alterations in androgen-dependent developmental end points, (2) determine whether prenatal exposure to finasteride permanently decreases AGD or results in nipple retention, and (3) evaluate whether AGD or nipple retention is predictive of adverse alterations in the male reproductive tract. Pregnant Crl:CD(SD)BR rats (n=5-6/group) were gavaged with either vehicle or finasteride at 0.01, 0.1, 1.0, 10, or 100 mg/kg/day on gestation days 12 to 21. All male offspring were monitored individually until necropsy on postnatal day (PND) 90. The present study design has been used previously for other antiandrogens and is sensitive to perturbations of the male rat reproductive tract. Decreases in AGD on PND 1 and increases in areolae-nipple retention on PND 13 were significantly different from controls in all finasteride-exposed male rats. Finasteride-induced changes in AGD and nipple retention were permanent in male rats exposed to finasteride at and above 0.1 mg/kg/day. On PND 90, dorsolateral and ventral prostate lobes were absent in 21 to 24% of rats exposed to 100 mg/kg/day finasteride and weighed significantly less at and above 10 mg/kg/day. In the highest dose group, 73% of animals had ectopic testes, much higher than previously reported. The most sensitive malformation other than decreased AGD and nipple retention was the dose-dependent increase in hypospadias. The lowest observed adverse effect level (LOAEL) for finasteride-induced permanent effects in this study was 0.1 mg/kg/day based on permanent changes in AGD and nipple retention. Finasteride-induced changes in AGD and retention of nipples were highly predictive of hypospadias, ectopic testes, and prostate malformations even though some animals with retained nipples or decreased AGD may not have had other reproductive tract malformations. In summary, prenatal exposure to finasteride specifically inhibited DHT-mediated development with little to no change in T-mediated development.     

Interactive effects of vinclozolin and testosterone propionate on pregnancy and sexual differentiation of the male and female SD rat.

In mammals, androgens are essential in directing mammalian sexual differentiation of the male phenotype. Administration of testosterone during this period alters female development in a male-like direction, whereas exposure to an androgen receptor antagonist like vinclozolin (V) demasculinizes and feminizes the male offspring. In the current study, we administered V (gavage at 200 mg/kg/day) and/or testosterone propionate (TP, sc, at 1 mg/rat/day), alone and in combination to Sprague-Dawley (SD) rats on days 14 through 19 of pregnancy, to determine if V would antagonize the effects of TP in the female and, conversely, if TP would antagonize the effects of V in the male offspring. These doses of TP and V were selected because they significantly alter sexual differentiation in the majority of female and male rat offspring, respectively, without producing severe toxicity in the dam or offspring. The study design is a 2 x 2 factorial (7 dams per group) including vehicle control, V, TP, and V + TP groups. As expected, individually, both V and TP reduced maternal weight gain and the V + TP group was affected in a cumulative fashion. Litter size on postnatal day (PND) 2 was reduced only by V + TP, whereas pup body weight was reduced in all three treated groups, the effect of V + TP again being cumulative. In female offspring, TP-induced alterations (i.e., increased anogenital distance [AGD] and fewer nipples, vaginal agenesis, hydrometrocolpos, induced prostate and bulbourethral glands, and levator ani muscle tissues) were all reversed by coadministration of V. In male offspring, V-induced alterations were only modestly antagonized by TP. At the dosage levels used herein, V + TP-treated male offspring had less well-developed nipples as infants and adults and a lower incidence of ectopic testis than did the V group. However, V-induced changes in reproductive organ weights, AGD, atrophic testes, vaginal pouch, and agenesis of the sex accessory tissues were not antagonized by concurrent TP treatment in male offspring. We observed that the combination of V and TP, two chemicals with opposing endocrine action, antagonized one another during sexual differentiation, especially in the female offspring and induced cumulative effects on maternal and neonatal toxicity. We suspect that antagonism of V by TP would be enhanced in the male if lower dose levels of V were used, but then the antagonism of TP by V in the female would likely be attenuated.     

Male rats exposed to linuron in utero exhibit permanent changes in anogenital distance, nipple retention, and epididymal malformations that result in subsequent testicular atrophy.

Prenatal exposure to the herbicide linuron, a weak androgen receptor antagonist, has been shown to perturb androgen-dependent male rat reproductive development as evidenced by slight decreases in anogenital distance (AGD), increased retention of areolae/nipples, and induction of epididymal malformations in combination with testicular atrophy in the adult rat over dose levels ranging from 12.5 to 100 mg/kg/day. Studies were undertaken to determine whether linuron-mediated changes in AGD and nipple retention are permanent, whether linuron is a direct testicular toxicant, and if there was an association between areola/nipple retention and malformations. Pregnant rats were administered corn oil vehicle or linuron by gavage at 0 or 50 mg/kg/day (n = 8 controls, 20 treated) from gestation days 12 to 21. Male offspring were necropsied on postnatal days (PND) 35 and 56. Linuron-exposed male rats exhibited a significant (8%) decrease in AGD on PND 1 and a similar decrease was also observed on PND 56. Linuron-exposed male rats displayed an increase in areola retention on PND 13, as evidenced by 0.6 +/- 0.5 and 3.3 +/- 0.4 areolae per rat in the control and exposed groups, respectively. Male rats displayed a significant increase in nipple retention on PND 35 and 56 (collectively) of 0 +/- 0.5 and 1.7 +/- 0.3 nipples per rat in control and exposed groups, respectively. On PND 35, 4/51 rats (3/9 litters) from linuron-treated dams displayed enlarged testes in combination with malformed epididymides. Epididymal malformations were observed in 19/51 rats (6/9 litters) in the linuron-exposed dose group. On PND 56, grossly enlarged and edematous testes were seen in 16/56 linuron-exposed rats (6/9 litters). Epididymal lesions were observed in 23/58 rats (6/9 litters). Microscopically, all linuron-exposed animals that exhibited a testicular lesion on PND 56 also displayed an epididymal lesion. These lesions were not seen in control animals. Approximately 25 and 60% of the male offspring that had malformations of the epididymis and vas deferens did not exhibit either areolae on PND 13 or nipples at necropsy, respectively. These data indicate that in utero linuron exposure to 50 mg/kg/day results in permanent changes in AGD and nipple retention in male rats. Moreover, these findings indicate that linuron-induced testicular atrophy, which is observed in adult rats, is secondary to increased intratubular pressure resulting from obstruction of testicular fluid outflow subsequent to malformation of the epididymides. These data also suggest that although linuron-mediated retention of areolae on PND 13 and nipples at necropsy may be suggestive of altered testosterone-mediated reproductive development seen in adult rats, these endpoints are not predictive.     

Assessment of dose-dependent reproductive toxicity of diclofenac sodium in male rats

Diclofenac sodium is widely used in the non-steroidal anti-inflammatory drug in the treatment of pain and inflammation. It is also particularly associated with its adverse effects on avian fauna and linked to environmental issues. The present study was aimed to assess the dose-dependent toxicity of diclofenac sodium on a male reproductive system of rats. Four groups of healthy adult fertile male rats were administered with saline (control) or 0.25?mg/kg, 0.50?mg/kg and 1.0?mg/kg of diclofenac sodium, respectively for 30 days. Alterations in body and organ weight, sperm and testicular cell population dynamics, serum biochemistry, histopathology, and hematology were investigated as per aimed objectives. Diclofenac sodium treatment significantly (p?≤?0.001) reduced weights of testis, epididymis, ventral prostate and seminal vesicle. Sperm count, sperm density (in epididymis and testis), sperm motility and testicular cell population dynamics were lowered in a dose-dependent manner. Administration of diclofenac exhibited varying degrees of degeneration testis, abnormal histo-architectures, and shrinkages in seminiferous tubules, particularly in higher doses. Diclofenac sodium treatments also altered hepatic and renal function parameters significantly. In conclusion, it may claim that diclofenac sodium treatment altered reproductive metabolic status, androgenic activities and histo-architecture of the testis of male rats and induced hepatotoxicity and renal toxicity.     

Effects on development of the reproductive system in male offspring of rats given butyl benzyl phthalate during late pregnancy

The objective of this study was to determine the effects of maternal exposure to butyl benzyl phthalate (BBP) on the development of the reproductive system in male offspring. Pregnant rats were given BBP by gastric intubation at 250, 500, or 1000 mg/kg on days 15 to 17 of pregnancy. A significant decrease in maternal body weight gain and food consumption was found in rats given BBP at 500 and 1000 mg/kg. A significant decrease in the number of live fetuses per litter was found at 1000 mg/kg. The weights of male and female fetuses were significantly decreased in the groups given BBP at 1000 mg/kg. A significant increase in the incidence of fetuses with undescended testes was found at 500 and 1000 mg/kg. A significant decrease in the anogenital distance (AGD) of male fetuses was observed at 500 and 1000 mg/kg. The AGD/cube root of body weight ratio in male fetuses was also significantly reduced at 500 mg/kg and higher. The AGD and AGD/cube root of body weight ratio of female fetuses in the BBP-treated groups were comparable to those in the control group. It was concluded that BBP on days 15 to 17 of pregnancy produced adverse effects on the development of the reproductive system in male offspring.     

Reproductive Toxicity and Tissue Concentrations of Low Doses of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Male Offspring Rats Exposed Throughout Pregnancy and Lactation

The effects of low doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the reproductive system of male offspring rats were examined. The dams were treated subcutaneously 2 weeks prior to mating and throughout mating, pregnancy, and lactation. They received an initial loading dose of 25, 60, or 300 ng TCDD/kg body wt, followed by a weekly maintenance dose of 5, 12, or 60 ng TCCD/kg body wt (TCDD 25/5, TCDD 60/12, and TCDD 300/60). Three dams per group were killed on Gestation Day 21 and the fetuses were removed. The concentration of TCDD in the maternal liver and fat was measured. After birth, developmental landmarks in male rats were monitored. At weaning, the concentration of TCDD in the offspring liver and testis was determined. Effects on male reproduction were studied on Postnatal Days (PND) 70 and 170. At weaning, the concentration of TCDD in the offspring liver was 0.24, 0.39, and 1.78 ng/g in the TCDD 25/5, TCDD 60/12, and TCDD 300/60 groups, respectively. In the testes, the concentration of TCDD was 0.25 ng/g in the TCDD 25/5 and TCDD 60/12 groups and 0.28 ng/g in the TCDD 300/60 group. The number of sperm per cauda epididymis was reduced in TCDD groups at puberty and at adulthood. Daily sperm production was permanently decreased as was the sperm transit rate in the TCDD-exposed male rats, thus increasing the time required by the sperm to pass through the cauda epididymis. Moreover, the male rats of the TCDD groups showed an increased number of abnormal sperm when investigated at adulthood. Similarly, mounting and intromission latencies were significantly increased in the TCDD 25/5 and TCDD 300/60 groups. In the highest dose group, serum testosterone concentration was decreased at adulthood. Likewise, in this dose group permanent changes including pyknotic nuclei and the occurrence of cell debris in the lumen were revealed. The lowest adverse effect level and the no observed effect level can be estimated to be substantially lower than the estimated daily dose of the lowest dose which is 0.8 ng/kg body wt/day. Sperm parameters were more susceptible than the other end points investigated. However, the question as to whether such doses exposed throughout gestation and lactation induce subtle changes in humans remains to be determined.     

Effect of butyl benzyl phthalate in Sprague-Dawley rats after gavage administration: a two-generation reproductive study

Butyl benzyl phthalate (BBP), a plasticizer, has been shown in in vitro studies to be weakly estrogenic, and in in vivo studies to possess testicular toxicity and teratogenicity, but few experimental data on BBP multigeneration effects on reproduction in mammals are available. The present two-generation reproductive study was conducted in male and female Sprague-Dawley rats using oral doses of 0, 20, 100, and 500 mg/kg/day BBP. Endpoints were chosen in order to evaluate both subchronic and reproductive toxicity. In the parent animals (F₀), a decrease in body weight gain was observed in males in the 500 mg/kg/day group, although no significant decrease in food consumption was found. No dose-related changes were observed in estrous cyclicity, fertility, or lactation. A dose-dependent increase in kidney weight in rats of both sexes, an increase in liver weight in males, and a decrease in the weight of the ovaries in females were observed. No macroscopic or microscopic changes were found in the reproductive system of males or females. Oral administration of BBP caused a decrease in the serum concentration of testosterone, and an increase in FSH. In the next generation (F₁), the body weight of male and female offspring at birth in the 100 and 500 mg/kg groups was significantly decreased, and the body weight in the 500 mg/kg group was lower throughout the study, while viability was not affected. Anogenital distance (AGD) at birth was decreased in male pups and was increased in female pups of the 500 mg/kg/day group. Preputial separation for male offspring in the 500 mg/kg/day group was delayed, while vaginal opening for female offspring in this group was not affected. BBP did not affect reproductive ability, including delivery and lactation, at any dose whereas macroscopic and microscopic changes of the testis, and decreased serum concentrations of testosterone were observed in male offspring of the 500 mg/kg/day group after puberty. From these data, it would appear that 20 mg/kg BBP is a no observed adverse effect level (NOAEL) for reproductive effects on parent animals and the next generation.     

Glyphosate impairs male offspring reproductive development by disrupting gonadotropin expression

Sexual differentiation in the brain takes place from late gestation to the early postnatal days. This is dependent on the conversion of circulating testosterone into estradiol by the enzyme aromatase. The glyphosate was shown to alter aromatase activity and decrease serum testosterone concentrations. Thus, the aim of this study was to investigate the effect of gestational maternal glyphosate exposure (50 mg/kg, NOAEL for reproductive toxicity) on the reproductive development of male offspring. Sixty-day-old male rat offspring were evaluated for sexual behavior and partner preference; serum testosterone concentrations, estradiol, FSH and LH; the mRNA and protein content of LH and FSH; sperm production and the morphology of the seminiferous epithelium; and the weight of the testes, epididymis and seminal vesicles. The growth, the weight and age at puberty of the animals were also recorded to evaluate the effect of the treatment. The most important findings were increases in sexual partner preference scores and the latency time to the first mount; testosterone and estradiol serum concentrations; the mRNA expression and protein content in the pituitary gland and the serum concentration of LH; sperm production and reserves; and the height of the germinal epithelium of seminiferous tubules. We also observed an early onset of puberty but no effect on the body growth in these animals. These results suggest that maternal exposure to glyphosate disturbed the masculinization process and promoted behavioral changes and histological and endocrine problems in reproductive parameters. These changes associated with the hypersecretion of androgens increased gonadal activity and sperm production.     

Study on developmental abnormalities in hypospadiac male rats induced by maternal exposure to di-n-butyl phthalate (DBP)

The objective of this study was to establish a hypospadiac rat model by maternal exposure to di-n-butyl phthalate (DBP) and to evaluate the developmental abnormalities of hypospadiac male rats. Timed-pregnant rats were given DBP by gastric intubation at doses of 0, 250, 500, 750 or 1000 mg/kg body weight (bw)/day from gestation day (GD) 14 to 18 to establish a hypospadiac rat model. The hypospadias was observed in the 500 and 750 mg/kg bw/day groups, the incidence of which was 6.8 and 41.3%, respectively. Transverse serial histological analysis of genitalia of hypospadiac male rats confirmed the malformation. With exposed dose increasing, the serum testosterone (T) levels of male rats inversely decreased, and in the same dosage group the serum T levels of hypospadiac rats were significantly lower than the levels of nonhypospadiac counterparts. The other reproductive lesions such as cryptorchidism and decreased ratio of anogenital distance/body weight (AGD/bw) were also observed. Autopsy analysis revealed the development of reproductive organs (prostate, testes, epididymis, pituitary gland) and nonreproductive organs (adrenal gland, liver, kidney, heart, spleen) of hypospadiac rats and nonhypospadiac counterparts. The results indicated that the reproductive system and developmental condition of hypospadiac male offspring were damaged severely by DBP.     

Characterization of the period of sensitivity of fetal male sexual development to vinclozolin.

Vinclozolin is a fungicide whose metabolites are androgen receptor (AR) antagonists. Previous work in our laboratory showed that perinatal administration of vinclozolin to rats results in malformations of the external genitalia, permanent nipples, reduced anogenital distance (AGD), and reduced seminal vesicle, ventral prostate, and epididymal weights. The objectives of this study were to determine the most sensitive period of fetal development to antiandrogenic effects of vinclozolin and to identify a dosing regime that would induce malformations in all of the male offspring. Pregnant rats were dosed with 400 mg vinclozolin/kg/day on either GD 12-13, GD 14-15, GD 16-17, GD 18-19, or GD 20-21, or with corn oil (2.5 ml/kg) from GD 12 through GD 21 (Experiment 1). All 2-day periods in which significant effects were produced were included in an extended dosing period, GD 14 through GD 19, in which pregnant rats were dosed with 200 or 400 mg vinclozolin/kg (Experiment 2). In Experiment 1, significant effects of vinclozolin were observed in rats dosed on gestation days (GD) 14-15, GD 16-17, and GD 18-19, while the most significant effects were observed in rats treated on GD 16-17. These effects include reduced AGD; presence of areolas, nipples, and malformations of the phallus; and reduced levator ani/bulbocavernosus weight. In contrast, ventral prostate weight was reduced only in the GD 18-19 group. The expanded dosing regime (Experiment 2) increased the percentage of male offspring with genital malformations (> 92%), and retained nipples (100%), further reduced the weight of the ventral prostate, and reduced the weight of the seminal vesicles. In addition, malformations were more severe and included vaginal pouch and ectopic/undescended testes. The latter was induced only in the 400 mg/kg group. These data indicate that the reproductive system of the fetal male rat is most sensitive to antiandrogenic effects of vinclozolin on GD 16 and 17, although effects are more severe and 100 % of male offspring are affected with administration of vinclozolin from GD 14 through GD 19.     

Adverse effects on development of the reproductive system in male offspring of rats given monobutyl phthalate, a metabolite of dibutyl phthalate, during late pregnancy

The objective of this study was to determine the adverse effects of monobutyl phthalate (MBuP), a major metabolite of dibutyl phthalate (DBP), on development of the reproductive system in offspring following maternal administration during late pregnancy, and to assess the role of MBuP in the antiandrogenic effects of DBP. Pregnant rats were given MBuP by gastric intubation at 250, 500, or 750 mg/kg on days 15 through 17 of pregnancy. Maternal body weight gain and food consumption during the administration period were significantly decreased at 500 mg/kg and higher and at 750 mg/kg, respectively. A significant increase in the incidence of postimplantation embryonic loss was found at 500 mg/kg and higher. The body weights of male and female fetuses were significantly lower at 750 mg/kg. A significant increase in the incidence of fetuses with undescended testes was found at 250 mg/kg and higher. A significant decrease in the anogenital distance (AGD) of male fetuses was observed at 250 mg/kg and higher. The AGD/body weight ratio and AGD/cube root of body weight ratio in male fetuses was also significantly reduced at 250 mg/kg and higher. The AGD, AGD/body weight ratio and AGD/cube root of body weight ratio in female fetuses in the MBuP-treated groups were comparable to those in the control group. The present study indicates that MBuP on days 15 to 17 of pregnancy produced adverse effects on the development of reproductive system in male offspring and suggest that MBuP may be responsible for the induction of the antiandrogenic effects of DBP.     

Reproductive effects of deltamethrin on male offspring of rats exposed during pregnancy and lactation

The effects of low doses of deltamethrin administered to female rats on the reproductive system of male offspring were examined. The dams (n=10-12/group) were treated daily by oral gavage with 0, 1.0, 2.0, and 4.0 mg deltamethrin/kg from day 1 of pregnancy to day 21 of lactation. Maternal and reproductive outcome data and male sexual development landmarks were assessed. Fertility, sexual behavior, and a large number of reproductive endpoints, such as organ weights, sperm evaluations, testosterone concentration, and testicular histology were examined on adult male offsprings. No signs of maternal toxicity were detected at the dose levels tested. Significantly adverse effects were only seen on testicular and epididymal absolute weights and the diameter of seminiferous tubules in the group treated with the highest dose of deltamethrin (4.0 mg/kg). The results indicate that in utero and lactational exposure to deltamethrin may induce subtle changes in reproductive behavior and physiology of male offspring rats at dose levels that do not cause maternal toxicity.