Maternal in utero exposure to the endocrine disruptor di-(2-ethylhexyl) phthalate affects the blood pressure of adult male offspring

Di-(2-ethylhexyl) phthalate (DEHP) is used industrially to add flexibility to polyvinyl chloride (PVC) polymers and is ubiquitously found in the environment, with evidence of prenatal, perinatal and early infant exposure in humans. In utero exposure to DEHP decreases circulating testosterone levels in the adult rat. In addition, DEHP reduces the expression of the angiotensin II receptors in the adrenal gland, resulting in decreased circulating aldosterone levels. The latter may have important effects on water and electrolyte balance as well as systemic arterial blood pressure. Therefore, we determined the effects of in utero exposure to DEHP on systemic arterial blood pressure in the young (2 month-old) and older (6.5 month-old) adult rats. Sprague-Dawley pregnant dams were exposed from gestational day 14 until birth to 300 mg DEHP/kg/day. Blood pressure, heart rate, and activity data were collected using an intra-aortal transmitter in the male offspring at postnatal day (PND) 60 and PND200. A low (0.01%) and high-salt (8%) diet was used to challenge the animals at PND200. In utero exposure to DEHP resulted in reduced activity at PND60. At PND200, systolic and diastolic systemic arterial pressures as well as activity were reduced in response to DEHP exposure. This is the first evidence showing that in utero exposure to DEHP has cardiovascular and behavioral effects in the adult male offspring.     

Taiwan food scandal: The illegal use of phthalates as a clouding agent and their contribution to maternal exposure

In 2011 the Taiwan Food and Drug Administration reported that plasticizers di(2-ethylhexyl) phthalate (DEHP) and di-iso-nonyl phthalate (DiNP), endocrine disruptors, were illegally added to clouding agents used in foods and beverages. 965 products were found contaminated, of which 206 were exported to 22 countries. This study’s purpose was to obtain English names for 28 contaminated products for which DEHP levels were reported, calculate estimated average daily intake (mg/kg/day) for a 50 kg woman consuming one portion, and compare to U.S. and E.U. guidelines for daily intake. We found that drinking just one bottle (500 ml) of sports drinks would result in an average DEHP intake of 0.14 mg/kg bw/day (range 0.091–0.341), which exceeds by several fold government guidelines (0.02–0.06 mg/kg bw/day). One (2 g) serving from 4/14 samples of contaminated dietary supplements exceeds the guideline of 0.02 mg/kg bw/day. In conclusion, consuming even one portion of tainted drinks and some powders would lead to daily intake of DEHP that greatly exceeds established safety guidelines, raising concerns about potential adverse effects, particularly reproductive tract development in the male fetus. Global distribution of DEHP-contaminated and other adulterated products should prompt governments to become proactive in food safety regulations and chemical testing.     

Chlorpyrifos induced reproductive toxicity in male mice

The reproductive toxicity of the insecticide chloropyrifos was studied in male mice. Adult male mice were treated by gavage with chloropyrifos at doses of 0, 5, 15, and 25 mg/kg-d for 4 weeks before mating with untreated females. Signs of cholinergic effects were observed in the 15 and 25 mg/kg-d treated groups. Brain and skeletal muscle acetylcholinesterase activity was inhibited in the same groups. Chloropyrifos treatment was associated with a decreased number of live fetuses, and an increased number of dead fetuses at 25 mg/kg-d. The number of early resorption was decreased in both 15 and 25 mg/kg-d treated groups. The percent morphologically normal spermatozoa were affected in 15 and 25 mg/kg-d dose groups; however, sperm motility and count were decreased in the same treated groups compared to the control. Histologic examination of brain revealed histological abnormalities in the middle and high groups. Dose related histologic changes, including degeneration of muscle fibers, were observed in the muscles of male mice treated with all the doses of chloropyrifos. The current study demonstrated adverse effects of male chloropyrifos exposure on pregnancy outcome with effects on sperm parameters at 15 and 25 mg/kg-d.     

Dose-related effect by maternal exposure to di-(2-ethylhexyl) phthalate plasticizer on inducing hypospadiac male rats

The aim of this study was to evaluate dose-related effects on external genitalia of adult male offspring rats by maternal exposure to di-(2-ethylhexyl) phthalate (DEHP) plasticizer. Timed-pregnant rats were given DEHP by gastric intubation at doses of 0, 500, 750 or 1000 mg/kg body weight/day from gestation day 12–19 to establish a hypospadiac rat model. The hypospadias was observed and the incidence in three DEHP dosage levels was 10.7%, 30.6% and 37.0%, respectively. With exposed dose increased, mild, moderate and severe hypospadiac rats were distinguished and an increased incidence of severe hypospadias was observed. The other reproductive lesions like reduced penile length and anogenital distance/body weight were observed. The results indicated the dose-related external genitalia teratogenic toxicity, and graded hypospadias on male offspring was resulted from high dosage DEHP maternal exposure.     

Disposition of diiosononyl phthalate and its effects on sexual development of the male fetus following repeated dosing in pregnant rats

Pregnant Sprague-Dawley rats received 50, 250, and 500 mg/kg/day diisononyl phthalate (DiNP) from GD 12 to 19 via corn oil gavage to study the dose response for effects on fetal male rat sexual development as well as metabolite disposition in the dam and fetus. Monoisononyl phthalate (MiNP), mono(carboxy-isooctyl) phthalate (MCiOP), mono(hydroxyl-isononyl) phthalate (MHiNP), mono(oxo-isononyl) phthalate (MOiNP), and monoisononyl phthalate glucuronide (MiNP-G) were found in all measured tissues. MCiOP was the major metabolite, followed in decreasing order by MiNP, MHiNP, MOiNP, and MiNP-G. Percentage of dose absorbed decreased at 750 mg/kg/day. Testosterone concentration in the fetal testes was reduced at 250 and 750 mg/kg/day. Multinucleated germ cells were increased in the testes of rats at 250 and 750 mg/kg/day. The no observed effect level (NOEL) for this study was 50 mg/kg/day based on increased MNGs and reduced testes testosterone concentration in the fetal rat.     

Di-(2-ethylhexyl) phthalate induces apoptosis of GC-2spd cells via TR4/Bcl-2 pathway

Di-(2-ethylhexyl) phthalate (DEHP) is a widely used environmental endocrine disruptor. Many studies have reported that DEHP exposure causes reproductive toxicity and cells apoptosis. However, the mechanism by which DEHP exposure causes male reproductive toxicity remains unknown. This study investigated the role of the testicular orphan nuclear receptor4 (TR4)/Bcl-2 pathway in apoptosis induced by DEHP, which resulted in reproductive damage. To elucidate the mechanism underpinning the male reproductive toxicity of DEHP, we sought to investigate apoptotic effects, expression levels of TR4/Bcl-2 pathway in GC-2spd cells, including TR4, Bcl-2 and caspase-3. GC-2spd cells were exposed to various concentrations of DEHP (0, 50, 100, or 200 μM). The results indicated that, with the increase of the concentrations of DEHP, the survival rate of cell decreased gradually. DEHP exposure at over 100 μM significantly induced apoptotic cell death. DEHP decreased SOD and GSH-Px activity in 200 μM group. Compared to the control group, the mRNA levels of caspase-3 increased significantly, however, Bcl-2 mRNA decreased (P < 0.05). In addition, there was a significant reduction in TR4, Bcl-2 and procaspase-3 protein levels. Taken together, these results lead us to speculate that in vitro exposure to DEHP might induce apoptosis in GC-2spd cells through the TR4/Bcl-2 pathway.     

A dose response study to assess effects after dietary administration of diisononyl phthalate (DINP) in gestation and lactation on male rat sexual development

Male rat sexual development was evaluated after dietary administration of 0, 760, 3800, 11,400 ppm diisononyl phthalate (DiNP) and 7600 ppm dibutyl phthalate (DBP) from gestation day (GD) 12 to postnatal day (PND) 14. Maternal weight was reduced on GD 20, PND 2 and 14 at 11,400 ppm DiNP. Pup weight was reduced on PND 2 and 14 at 11,400 and 3800 ppm DiNP. DBP induced multinucleated germ cells (MNGs) and Leydig cell aggregates (LCAs) in PND 2 testes. 7600 ppm DBP reduced anogenital distance (AGD) on PND 2 and 14, and increased nipple retention and reproductive tract malformations on PND 49. DiNP induced MNGs (3800 ppm) and LCAs (11,400 ppm) on PND 2, and reduced AGD (11,400 ppm) on PND 14. DiNP did not alter AGD, nipple retention or reproductive tract malformations on PND 49. Global endpoint analysis showed no evidence of a rat “phthalate syndrome” on PND 49 with DiNP administration.     

Absence of neurotoxicity with medicinal grade terbutaline in the rat model

To evaluate neurological effects of terbutaline, rats were injected with saline, terbutaline (Sigma or American Pharmaceutical Partners (APP?)) at 0.5 mg/kg-d or 10 mg/kg-d between postnatal days (PND) 2–5 or 11–14. Brains collected 24 h after last injection were used to determine corpus-callosum thickness, Purkinje cell and neuronal number in the cerebellum. Ambulation, distance traveled, resting time and time on rotarod were analyzed. Terbutaline (both doses/grades at PND 11–14) decreased corpus-callosum thickness. Ambulation time was significantly decreased in the 10 mg/kg-d (Sigma) and 0.5 mg/kg-d of terbutaline (APP?) (PND 2–5) juvenile-rats and 10 mg/kg-d-Sigma adult-rats, 0.5 mg/kg-d APP? (PND 11–14) adult-rats. Resting time was increased in both doses of APP? (PND 2–5) in juvenile-rats, 10 mg/kg-d Sigma adult-rats. 10 mg/kg-d-Sigma (PND 2–5) decreased distance traveled in adult-rats. 0.5 mg/kg-d-Sigma (PND 2–5 and PND 11–14) decreased the time spent on rotarod (30 RPM) in adult-rats. Sigma terbutaline Sigma had 2× as much free base compared to APP?. In conclusion, APP? terbutaline did not have a deleterious effect on the developing rat brain.     

Neonatal exposure to bisphenol A reduces the pool of primordial follicles in the rat ovary

We evaluated whether exposure to bisphenol A (BPA) disrupts neonatal follicle development in rats. From postnatal day 1 (PND1) to PND7, pups received corn oil (control), diethylstilbestrol (DES20: 20 μg/kg-d, DES0.2: 0.2 μg/kg-d), or BPA (BPA20: 20 mg/kg-d, BPA0.05: 0.05 mg/kg-d). We examined follicular dynamics, multioocyte follicles (MOFs) incidence, proliferation and apoptosis rates, expression of steroid receptors (ERα, ERβ, PR, AR) and cyclin-dependent kinase inhibitor 1B (p27) in PND8 ovaries. DES20, DES0.2 and BPA20-ovaries showed fewer primordial follicles and increased growing follicles. DES20-ovaries exhibited increased incidence of MOFs. Oocyte survival, AR, PR and apoptosis were not changed. Primordial and recruited follicles from BPA20-ovaries showed higher p27, whereas ERβ and proliferation were both increased in recruited follicles. ERα positive primary follicles increased in BPA 20-ovaries. Results show that BPA reduces the primordial follicle pool by stimulating the neonatal initial recruitment, associated with an increased proliferation rate likely mediated by an estrogenic pathway.     

Human biofluid concentrations of mono(2-ethylhexyl)phthalate extrapolated from pharmacokinetics in chimeric mice with humanized liver administered with di(2-ethylhexyl)phthalate and physiologically based pharmacokinetic modeling

Di(2-ethylhexyl)phthalate (DEHP) is a reproductive toxicant in male rodents. The aim of the current study was to extrapolate the pharmacokinetics and toxicokinetics of mono(2-ethylhexyl)phthalate (MEHP, a primary metabolite of DEHP) in humans by using data from oral administration of DEHP to chimeric mice transplanted with human hepatocytes. MEHP and its glucuronide were detected in plasma from control mice and chimeric mice after single oral doses of 250 mg DEHP/kg body weight. Biphasic plasma concentration–time curves of MEHP and its glucuronide were seen only in control mice. MEHP and its glucuronide were extensively excreted in urine within 24 h in mice with humanized liver. In contrast, fecal excretion levels of MEHP glucuronide were high in control mice compared with those with humanized liver. Adjusted animal biomonitoring equivalents from chimeric mice studies were scaled to human biomonitoring equivalents using known species allometric scaling factors and in vitro metabolic clearance data with a simple physiologically based pharmacokinetic (PBPK) model. Estimated urine MEHP concentrations in humans were consistent with reported concentrations. This research illustrates how chimeric mice transplanted with human hepatocytes in combination with a simple PBPK model can assist evaluations of pharmacokinetics or toxicokinetics of the primary or secondary metabolites of DEHP.     

The effect of perfluorododecanonic acid on endocrine status,sex hormones and expression of steroidogenic genes in pubertal female rats

Perfluorododecanoic acid (PFDoA), one of a number of commercially important perfluoroalkyl acids, has been detected in sera from humans and other animals; however, the effects of PFDoA on female reproduction remain unclear. To assess the impact of PFDoA on puberty and endocrine status, we exposed weaned pre-pubertal female rats to PFDoA, administered orally at doses of 0, 0.5, 1.5 and 3 mg/kg-d for 28 days, and measured body weight, reproductive organ weight and morphology, pubertal indicators, endocrine hormones, total serum cholesterol levels and steroidogenic enzyme gene expression. At 3 mg/kg-d, PFDoA significantly decreased body weight and serum estradiol levels, increased cholesterol levels (p < 0.05), and altered ovarian expression of genes responsible for cholesterol transport and steroidogenesis, including steroidogenic acute regulatory protein, cholesterol side-chain cleavage enzyme and 17-beta-hydroxysteroid dehydrogenase (p < 0.05). PFDoA at the highest dose also reduced estrogen receptor α and β expression levels in the ovary (p < 0.05), whereas a lower concentration of PFDoA (0.5 mg/kg-d) decreased estrogen receptor β mRNA levels in the uterus (p < 0.05). PFDoA treatment did not affect serum follicle-stimulating hormone or luteinizing hormone (LH) levels at any concentration, although PFDoA at 3 mg/kg-d reduced LH receptor mRNA levels. There were no marked changes in sexual organ weight, age and weight at vaginal opening or first estrous cycle, or ovarian/uterine histology at any PFDoA concentration. These data show that PFDoA does not affect the endocrine status of pubertal rats, but at higher doses it does impact estradiol production and the expression of some key genes responsible for estrogen synthesis.     

Oxidative stress mediates dibutyl phthalateinduced anxiety-like behavior in Kunming mice

Among all phthalate esters, dibutyl phthalate (DBP) is only second to di-(2-ethylhexyl) phthalate (DEHP) in terms of adverse health outcomes, and its potential cerebral neurotoxicity has raised concern in recent years. DBP exposure has been reported to be responsible for neurobehavioral effects and related neurological diseases. In this study, we found that neurobehavioral changes induced by DBP may be mediated by oxidative damage in the mouse brain, and that the co-administration of Mangiferin (MAG, 50 mg/kg/day) may protect the brain against oxidative damage caused by DBP exposure. The results of ethological analysis (elevated plus maze test and open-field test), histopathological examination of the brain, and assessments of oxidative stress (OS) in the mouse brain showed that there is a link between oxidative stress and anxiety-like behavior produced by DBP at higher doses (25 or 125 mg/kg/day). Biomarkers of oxidative stress encompass reactive oxygen species (ROS), glutathione (GSH), malondialdehyde (MDA) and DPC coefficients (DPC). MAG (50 mg/kg/day),administered as an antioxidant,can attenuatetheanxiety-like behavior of the tested mice.     

Chronic oral treatment with isotretinoin alters measures of activity but not anxiety in male and female rats

Use of the anti-acne drug, Accutane® (ACC) (isotretinoin, 13-cis-retinoic acid), has been associated with neuropsychiatric events ranging from depression in animal models to depression and suicide ideation in humans. Our studies, however, have consistently indicated few effects on measures of depression in male and female rats. Still, the comorbidity of depression and anxiety suggests that anxiety assessments in ACC-treated rats could be informative. Such assessments must be balanced with measures of activity since drug-induced activity alterations may impact the expression of anxiety-like behaviors. Here, Sprague–Dawley rats (n = 15/sex/dose) were gavaged daily with 0 (soy oil), 7.5, or 30 mg/kg/day ACC beginning on postnatal day (PND) 59. Blood ACC levels similar to humans taking recommended ACC doses are produced by 7.5 mg/kg/day. Short-term activity was assessed in open fields prior to ACC treatment (PND 51) and again at PNDs 129 and 164 and in a complex environment at PNDs 66 and PND 184. Long-term residential activity was measured in running wheels (PNDs 85–92) and figure 8 mazes (PNDs 99–106). Anxiety-like behavior was assessed via elevated plus maze (EPM) activity on PND 98 and in a black/white apparatus on PND 125. The typical sex differences in most behaviors were exhibited (i.e., increased EPM open arm entries and overall activity in most measures in females); however, there were no significant effects of ACC treatment on open field activity, complex environment activity, residential running wheel activity, or EPM activity. Residential figure 8 maze activity indicated that male and female rats treated with 30 mg/kg/day were less active on all nights (p < 0.05) and females treated with 7.5 or 30 mg/kg/day were less active than same-sex controls on most days (p < 0.05). Similarly, rats of both sexes treated with 30 mg/kg/day were significantly less active in the black/white apparatus (p < 0.05), entering the darkened area less frequently (p < 0.05), although duration in the darkened area did not differ. These data indicate that at blood levels typically achieved by humans (i.e., the 7.5 mg/kg group), there are no significant anxiogenic effects associated with ACC treatment. At higher ACC levels, there are mild effects on activity but these appear to be apparatus- and/or age-specific.     

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.     

Assessing the relevance of in vitro measures of phthalate inhibition of steroidogenesis for in vivo response

Human phthalate exposure occurs as mixtures of diesters with varying activity towards testosterone-dependent development. Dibutyl (DBP), diethylhexyl (DEHP) and butylbenzyl (BBP) phthalate disrupt sexual development in the fetal rat. Dimethyl (DMP) and diethyl (DEP) phthalate do not. These differences in potency may result from differential delivery of the monophthalates to the testes or from variation in the abilities of the compounds to alter steroidogenesis. We tested five phthalates in pregnant rats (500 mg/kg-d, GD12–19) and analyzed the fetal testes for corresponding monoesters (MMP, MEP, MBP, MEHP, MBeP). Testes MMP and MEP levels were 2–40-fold higher than the active monoesters, MBP and MEHP. BBP exposure led to low concentrations of MBeP, but similar MBP levels to DBP. An in vitro MA-10 cell assay measured the direct effect of monophthalates on testosterone production. MEHP inhibited LH-stimulated testosterone production at 1 μM. RT-PCR confirmed down-regulation of genes associated with cholesterol transport and steroid synthesis and metabolism by MEHP. Five additional phthalates were tested for testosterone inhibition. MBP and mono-n-octyl phthalate were similar to MEHP; MMP, MEP and MBeP were poor inhibitors of testosterone production. Based on these results, differences in the phthalates’ ability to interfere with sexual development in vivo appears to be more associated with differential potency for testosterone inhibition than differences in tissue doses.     

Kinetics of selected di-n-butyl phthalate metabolites and fetal testosterone following repeated and single administration in pregnant rats

Human exposure to phthalic acid diesters occurs through a variety of pathways as a result of their widespread use in consumer products and plastics. Repeated doses of di-n-butyl phthalate (DBP) from gestation day (GD) 12 to 19 disrupt testosterone synthesis and male sexual development in the fetal rat. Currently little is known about the disposition of DBP metabolites, such as monobutyl phthalate (MBP) and its glucuronide conjugate (MBP-G), during gestation after repeated exposure to DBP. In order to gain a better understanding of the effect of repeated dosing on maternal and fetal metabolism and distribution, pregnant Sprague–Dawley rats were given a single dose of 500 mg/kg DBP on GD 19 or daily doses of 50, 100, and 500 mg/(kg day) from GD 12 to 19 via corn oil gavage. Dose–response evaluation revealed a non-linear increase in maternal and fetal plasma concentrations of MBP. Maternal and fetal MBP levels were slightly lower in animals after 8 days of dosing at 500 mg/(kg day). Fetal plasma MBP levels closely followed maternal plasma, while the appearance and elimination of MBP-G in fetal plasma were significantly delayed. MBP-G accumulated over time in the amniotic fluid. Inhibition of testosterone was rapid in fetal testes when exposed to DBP (500 mg/(kg day)) on GD 19. Within 24 h, the level of inhibition in the fetus was similar between animals exposed to a single or multiple daily doses of 500 mg/(kg day). Examination of testosterone time-course data indicates a rapid recovery to normal levels within 24 h post-dosing at DBP doses of 50 and 100 mg/(kg day), with a rebound to higher than normal concentrations at later time-points. MBP kinetics in fetal testes allows direct comparison of active metabolite concentrations and testosterone response in the fetal testes.     

Estrogenicity of food-associated estrogenic compounds in the fetuses of female transgenic mice upon oral and IP maternal exposure

The present study investigated to what extent seven food-associated in vitro estrogenic compounds can induce estrogenic effects in the fetuses of pregnant female mice with an estrogen receptor (ER)-mediated luciferase (luc) reporter gene system. The luc-induction was determined either 8 h after maternal dosing with a single intraperitoneal (IP) dose or 24 h after the last of a series of 8 daily oral dosages. Three known estrogens, 17β-estradiol (E₂), 17α-ethynylestradiol (EE) and 17β-estradiol 3,17-dipropionate (EP) were used as positive controls at 1 mg/kg bw and DMSO as solvent control. The food-associated estrogenic compounds tested were: bisphenol A (BPA), nonylphenol (NP) both at 50 mg/kg bw, dichlorodiphenyldichloroethylene (p,p′-DDE) at 50 mg/kg bw, quercetin at 16.6 mg/kg bw, and di-isoheptyl phthalate (DIHP), di-(2-ethylhexyl) phthalate (DEHP) and di-(2-ethylhexyl) adipate (DEHA) all at 100 mg/kg bw. Exposure to E₂, EE and EP resulted in significant luc inductions upon both oral and/or IP dosing in a variety of tissues including liver, tibia and femurs, and upon IP dosing also in fetuses.BPA, NP, DEHA, DEHP, DIHP, DDE and quercetin were unable to significantly induce luc activity in fetuses. However, after maternal oral exposure during gestation to NP, BPA and DIHP placental luc activity was significantly lowered.The results indicate that at the current levels of exposure to food-associated estrogenic compounds, estrogenic effects to the fetus are not expected. The significant luc reduction in the placenta, should be further studied for its significance for fetal development and relevance for the human situation.     

Effects of n-butylparaben on steroidogenesis and spermatogenesis through changed E2 levels in male rat offspring

Parabens are widely used as antibacterial agents, which are concerned recently in the relationship between the use of parabens and reproductive toxicity. So that reassessment of the risk of parabens is needed. In this study, one of parabens, n-butylparaben (n-BP) was orally administered to pregnant Wistar rats (0, 64, 160, 400 and 1000 mg/kg/day) from gestation day (GD) 7 through postnatal day (PND) 21. Reduced anogenital distance (AGD) and delayed preputial separation (PPS) were observed in the male offspring. The weights of the testes were significantly reduced at PND 21–90. The weights of the epididymides were significantly reduced at all monitoring points, except PND 35. Seminal vesicle weights were significantly reduced on PND 21. Serum testosterone (T) was significantly decreased, especially on PND 49. The levels of 17β-estradiol (E₂) showed an increase at each of the tested points except on PND 180. Serum luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels in the n-BP treated groups were lower on PND 21, 35 and 49 but elevated on PND 90 compared to control levels. n-BP reduced epididymal cauda sperm counts and daily sperm production in a dose-dependent manner; this difference was statistically significant at exposure groups of 400 and 1000 mg/kg/day. The present study strongly suggests that exposure to n-BP in utero and during lactation has adverse effects on the reproductive system in male offspring, with a no observed adverse effect level (NOAEL) of 160 mg/kg/day. To our knowledge, this is the first study that reports increased E₂ levels of male rats following n-BP exposure; we suggest that E₂ levels may be considered as biomarkers for some endocrine disrupting chemicals (EDCs).     

In utero exposure to the endocrine disruptor di(2-ethylhexyl) phthalate targets ovarian theca cells and steroidogenesis in the adult female rat

Di-2-ethylhexyl phthalate (DEHP) is an endocrine disruptor used in industry as an additive to polyvinyl chloride-based products. Pregnant dams were gavaged with oil, 1, 20, 50, or 300 mg of DEHP/kg/day from gestational day 14 until birth in order to characterize the effects of DEHP in the adult female offspring. In utero exposure to DEHP resulted in reduced estrogen levels at proestrus. Theca cell layer thickness was decreased starting at 50 mg DEHP/kg/day dose. Follicle-stimulating hormone levels were significantly increased at proestrus and estrus. F1 reproduction using a known breeder was not affected. F3 generation showed a decreased pregnancy rate and weight, and increased litter size in the animals exposed to 20 mg DEHP/kg/day. The data presented herein suggest that in utero exposure to DEHP targets the theca cell layer and decreases the estrus cycle steroid surge, but despite these effects, does not cause infertility.     

Effects of maternal exposure to di-n-butyl phthalate during pregnancy and breastfeeding on ovarian development and function of F1 female rats

This study aimed to investigate the effects of maternal exposure to di-n-butyl phthalate (DBP) during pregnancy and breastfeeding on F1 ovarian development and function. A rat model of maternal exposure to DBP during pregnancy and breastfeeding was established by gavage feeding female Sprague Dawley rats with 0, 10, 100, or 600 mg/kg/day DBP from gestational day (GD) 12 to postnatal day (PND) 21. F1 offspring were weaned on PND21 and were not exposed to DBP afterward. The age of vaginal opening and estrus onset, estrous cyclicity, c-Kit-ligand expression on ovarian granulosa cells, and the weight of ovaries and uterus of F1 female offspring were not affected, whereas serum levels of estradiol and progesterone were increased significantly by maternal exposure to 10 mg/kg/day DBP from GD12 to PND21. Although F1 ovarian function may not be adversely affected by maternal exposure to DBP, the increased reproductive hormone levels may interfere in F1 rat fertility.