Number Of Live Pups Research Articles

Evaluation of Reproductive Disorders in Female Rats Exposed to N‐Methyl‐2‐Pyrrolidone

N-methyl-2-pyrrolidone (NMP) is a solvent used in the petrochemical, and electronic industries, in pesticides production, veterinary drugs, and paint removers. The aim of study was to evaluate the relationship between the dose of NMP given orally and its effect on fertility in female rats and early development of their progeny. Females were exposed by gavage 5 days/week to NMP at 150, 450, or 1000mg/kg/day 2 weeks before mating, during mating, gestation, and lactation. On the first postnatal day (PND 1), the live and dead pups were counted, weighed, and gender was determined. On PND 4, the litters were culled to eight animals each and balanced for gender. Young animals were observed during 3 weeks after birth. Fertility index did not significantly differ in the control and the group exposed at 150mg/kg/day but it was significantly lower in the groups exposed at 450 or 1000mg/kg/day. The number of live pups in the group exposed to the highest dose was significantly lower and the number of stillbirths in litters was significantly greater. Survival of the pups from all exposed groups during the 3 weeks after birth was significantly lower than the control animals. The results of our study indicate that intragastric exposure of female rats to NMP before pregnancy during gestation causes significant impairment in female fertility and intrauterine mortality rates. At lower doses, toxic or slightly toxic to the mothers, this substance causes decrease in viability and physical development of progeny.

The Effect of Kraussianone‐2 (Kr2), a Natural Pyrano‐isoflavone from Eriosema kraussianum, in an L‐NAME‐ induced Pre‐eclamptic Rat Model

This study aimed to investigate the effects of Kraussianone-2 (Kr2), a pyrano-isoflavone isolated from the roots of Eriosema kraussianum N. E. Br. (Fabaceae) on various fetal and physiological parameters in pregnant, L-NAME treated Sprague-Dawley rats. Twenty-four pregnant Sprague-Dawley dams were divided into three groups (n = 8), i.e. the control group (CON), the experimental control group (PRE), where the pre-eclampsia-like symptoms were induced using L-NAME, and the experimental group (EK2), where the pre-eclampsia-like symptoms were once again induced using L-NAME, however, these animals were treated with Kr2. On gestation day 20 the animals were sacrificed, at which time a laparotomy was performed and the number of live pups were counted and their corresponding birth and placental weights were recorded. Blood was also collected in heparin-coated tubes and the plasma samples were then analysed for specific variables using commercially available kits for rats. Kraussianone-2 administration decreased fetal mortality and demonstrated a trend toward increasing birth and placental weights in this model. Furthermore, Kr2 administration also reduced blood pressure amplification and decreased the plasma concentrations of two antiangiogenic factors, soluble fms-like tyrosine kinase1 (sFlt-1) and soluble endoglin (sEng). We speculate that Kr2, by improving uterine artery blood flow, results in improved fetal outcomes and decreased antiangiogenic factors in pregnant, L-NAME treated, Sprague-Dawley rats.

Repeated dose and reproductive/developmental toxicity of perfluorooctadecanoic acid in rats

Male and female rats were given perfluorooctadecanoic acid (PFOdA) by gavage at 40, 200 or 1,000 mg/kg/day, and each female was mated with a male in the same dose group after 14-day administration. Males were dosed for 42 days and females were dosed throughout the gestation period until day 5 of lactation. One female given 1,000 mg/kg/day was euthanized on day 18 of gestation due to a moribund condition; however, no other treatment-related clinical signs of toxicity were observed. Body weights fell at 1,000 mg/kg/day from day 28 through the administration period in males and throughout gestation and lactation in females. Red blood cell count, hemoglobin level and hematocrit were decreased at 200 and 1,000 mg/kg/day in males and activated partial thromboplastin time was prolonged at 1,000 mg/kg/ day in females. Histopathological examination revealed hepatic changes, such as centrilobular hypertrophy and necrosis, in males given 200 and 1,000 mg/kg/day and in females given 1,000 mg/kg/day. Pancreatic zymogen granule was decreased in both sexes at 1,000 mg/kg/day. As for reproductive and developmental toxicity, there were decreases in the number of corpora lutea, implantation, total number of pups born and the number of live pups on postnatal days 0 and 4 at 1,000 mg/kg/day. At this dose, birth weights of pups were decreased and postnatal body weight gain was inhibited. Based on these findings, the NOAEL of PFOdA was considered to be 40 mg/kg/day for repeated dose toxicity and 200 mg/kg/day for reproductive/developmental toxicity.

139: Foxp3+ regulatory T cells sustain pregnancy through a CTLA-4 independent pathway

through a CTLA-4 independent pathway Marijo Aguilera, Jared Rowe, James Ertelt, Kirk Ramin, Sing Sing Way University of Minnesota, Maternal Fetal Medicine, Minneapolis, MN, University of Minnesota, Department of Pediatrics and Microbiology, Minneapolis, MN OBJECTIVE: Establishing the immune basis whereby pregnancy is sustained remains an area of paramount importance. Our prior studies have established an essential role for the sustained expansion of maternal immune-suppressive Foxp3 regulatory T cells (Treg) in maintaining tolerance to the developing fetus. Given the heterogeneity in Treg usage of defined molecules for context-specific immune suppression, we sought to identify the Treg-associated molecules required for maintaining pregnancy. STUDY DESIGN: Mating with MHC mismatched strains of mice was used to recapitulate the natural heterogeneity between maternal and fetal antigen. At mid-gestation when the expansion of maternal Tregs peaks, mice were treated with neutralizing antibody against defined Treg-associated molecules. In particular, we focused on Cytotoxic T lymphocte-associated antigen-4 (CTLA-4) because this molecule is essential for Treg-mediated immune suppression in other contexts. The impacts on pregnancy outcomes (fetal resorption and number of live pups born) were enumerated. To investigate the maternal response to fetal antigen, transgenic male mice expressing ovalbumin (OVA) were used for breeding with non-OVA-expressing females allowing the response to the surrogate fetal-OVA antigen to be tracked using well-characterized cellular immunology tools. RESULTS: The number of live pups born to pregnant mice treated with anti-CTLA-4 compared with isotype antibody was modestly reduced, but this difference did not reach statistical significance (6.68 / 0.44 vs 7.75 / 0.40; p 0.095). Similarly, anti-CTLA-4 antibody did not trigger fetal resorption, or prime the expansion of fetal specific T cells among maternal immune cells (fetal-OVA-specific among total CD8 T cells were 0.55 / 0.18 and 0.39 / 0.09 percent; p 0.501 for anti-CTLA-4 and isotype antibody treated mice, respectively). CONCLUSION: Although the expansion of maternal Tregs is essential for sustaining tolerance to the developing fetus and these cells have been shown to utilize CTLA-4 for immune suppression in other contexts, CTLA-4 plays non-essential roles in maintaining pregnancy.

Hepatic peroxisome proliferator-activated receptor α may have an important role in the toxic effects of di(2-ethylhexyl)phthalate on offspring of mice

Maternal exposure to di(2-ethylhexyl)phthalate (DEHP) is associated with adverse effects on offspring, and the metabolites are agonists of peroxisome proliferator-activated receptor (PPAR) α, which exhibits species differences in expression and function. This study aimed to clarify the mechanism of DEHP-induced adverse effects on offspring in relation to maternal mouse and human PPARα. Male and female Sv/129 wild-type (mPPARα), Pparα-null and humanized PPARα (hPPARα) mice were treated with diets containing 0%, 0.01%, 0.05% (medium) or 0.1% (high) DEHP. After 4 weeks, males and females were mated. Dams were killed on gestational day 18 and postnatal day (PND) 2. High-dose DEHP decreased the number of total and live fetuses, and increased resorptions in mPPARα mice. In hPPARα mice, resorptions were increased above the medium dose, and the number of births was decreased at the high dose. The number of live pups on PND2 was decreased over the medium dose in mPPARα and at the high dose in hPPARα mice. No such findings were observed in Pparα-null mice. High-dose DEHP decreased plasma triglyceride in pregnant mPPARα mice, but not in Pparα-null and hPPARα ones. Above the medium dose in mPPARα mice significantly reduced hepatic microsomal triglyceride transfer protein (MTP) expression. Medium- and/or high-dose DEHP increased the levels of maternal PPARα target genes in mPPARα and hPPARα mice. Taken together, PPARα expression is required for the toxicity of DEHP in fetuses and pups and altered plasma triglyceride levels, through regulation of MTP may be important in mPPARα mice and not in hPPARα mice.

Toxic effect of gestational exposure to nonylphenol on F1 male rats

The purpose of this study was to examine whether gestational exposure to major environmental endocrine-disrupting chemicals, nonylphenol (NP), would lead to nerve behavioral and learning and memory capacity alterations in the male offspring of rats, and reproductive development alterations in the male offspring of rats. Dams were gavaged with NP at a dose level of 50 mg/kg/day, 100 mg/kg/day or 200 mg/kg/day daily from gestational day 9 to 15, and at a dose level of 40 mg/kg/day, 80 mg/kg/day or 200 mg/kg/day daily from gestational day 14 to 19 (transplacental exposures). Exposure to 200 mg/kg/day NP produced a significant decrease in learning and memory functions in offspring rats (P<0.05) in Morris water maze task, as demonstrated by the increased escape latency and number of error. In Step-down Avoidance Test, offspring rats exposed to NP spent more reaction time (RT) and presented lower latency to first step-down than the control offspring (P<0.01). In utero exposure to 80 and 200 mg/kg/day NP produced a significant decrease in the number of live pups per litter and ratio of anogenital distance to body length on PND 0 (P<0.05), and also testes and prostate weight, activities of ALP, plasma testosterone concentration, cauda epididymis sperm counts, daily sperm production et al. respectively on PND 90 (P<0.05). Histopathological examination of the brain biopsy illustrates that exposure to NP at high dose induces the presence of abnormal distribution of spermatozoa showed in lumina of the seminiferous tubules, and absence of spermatogenesis and spermiogenesis. Gestational exposure to nonylphenol might induce neurotoxic and reproductive toxic effects on F1 male rats.

Reproductive and Developmental Toxicity of Amitraz in Sprague-Dawley Rats

The present study was conducted to obtain information on the effects of amitraz on reproductive and developmental parameters in rats. The test chemical was administered via the drinking water containing 0, 40, 120, and 360 ppm to male rats from 2 weeks before mating to the end of 14-day mating period and to females from 2 weeks before mating, throughout mating, gestation and up to lactational day 4. During the study period, clinical signs, body weights, food intake, organ weights, reproductive and littering findings, necropsy findings, sperm parameters, and histopathology were examined. At 360 ppm, decreases in the body weight gain, food consumption, and the number of live pups and an increase in the post-implantation loss were observed. In addition, decreases in the seminal vesicle weight and sperm motility were found in males. At 120 ppm, a decrease in the food consumption was found transiently in both males and females, but no reproductive and developmental toxicity was observed in both sexes. There were no signs of either general or reproductive and developmental toxicity in the 40 ppm group. Based on these results, it was concluded that the repeated oral administration of amitraz to rats resulted in a decrease in the food consumption at 120 ppm and decreases in the seminal vesicle weight, sperm motility, and the number of live pups and an increase in the post-implantation loss at 360 ppm in rats. Under these experimental conditions, the no-observed-adverse-effect level (NOAEL) of amitraz for general and reproduction/developmental toxicity was believed to be 120 ppm, and the no-observed-effect level (NOEL) of amitraz was believed to be 40 ppm in rats.

A High Dose of IMT504, the PyNTTTTGT Prototype Immunostimulatory Oligonucleotide, Does Not Alter Embryonic Development in Rats

Synthetic oligodeoxynucleotides (ODNs) are currently being evaluated as vaccine adjuvants for inducing protective immunity. As maternal vaccination is becoming increasingly common, the potential risk of vaccine formulation using ODN adjuvants should be warranted. A recent study performed in mice suggests that exposure to CpG motifs during pregnancy could result (although at very high doses as compared to the ones proposed for human vaccination) in fetal loss and morphological defects. PyNTTTTGT ODNs are immunostimulatory ODNs not bearing CpG motifs, which are very efficient vaccine adjuvants. In this report, we analyzed the potential teratogenic effect of its prototype IMT504 in rats. This animal model was chosen because PyNTTTTGT ODNs are barely active in mice. Intraperitoneal injection of IMT504 at a dose of 20 mg/kg (more than 1000 times higher than the one proposed for a vaccine dose in humans) at day 6 of pregnancy did not produce a significant decrease in the mean number of implanted fetuses or in the number of live pups delivered. Neither the fetuses nor the offspring presented malformations.

Reproductive and developmental toxicity screening study of 2,4‐dinitrophenol in rats

Rats were treated by gavage once daily with 2,4-dinitrophenol (DNP) at 0 (control), 3, 10, or 30 mg/kg bw. Males were dosed for 46 days, beginning 14 days before mating, and females were dosed for 40-47 days, from 14 days before mating to day 3 of lactation. No deaths were observed in males and females of any group. A significant decrease in body weight gain and significant increase in liver weight were found in males and females at 30 mg/kg bw/day. The number of live pups on postnatal days (PNDs) 0 and 4, live birth index, and body weight of live male and female pups on PNDs 0 and 1 were significantly lowered at 30 mg/kg bw/day. External and internal examinations of pups revealed no increased incidence of malformations in DNP-treated groups. On the basis of these findings, we concluded that DNP has general and reproductive/developmental toxicity, but not teratogenicity, under the present conditions. The NOAEL of DNP is considered to be 10 mg/kg bw/day in rats.

Reproductive and developmental toxicity screening test of tetrahydrofurfuryl alcohol in rats

Twelve male and female rats per group were given tetrahydrofurfuryl alcohol (THFA) by gavage at 0, 15, 50, 150 or 500 mg/kg/day. Males were dosed for 47 days, beginning 14 days before mating, and females were dosed for 42–52 days beginning 14 days before mating to day 4 of lactation throughout the mating and gestation period. Changes in locomotor activity, inhibition of body weight gain, and/or histopathological changes in the thymus, spleen, testes and/or epididymides were observed in males and females at 150 mg/kg and above. No effects of THFA were found on the copulation index, fertility index, or the number of corpora lutea and implantations in pregnant females. At 500 mg/kg, no pregnant females delivered any pups. At 150 mg/kg, gestation length was prolonged, and the total number of pups born and the number of live pups on postnatal days 0 and 4 was markedly decreased. No effects of THFA were found on the sex ratio and body weight of live pups, or the incidence of pups with malformations or variations. Based on these findings, the NOAELs for parental and reproductive/developmental toxicity of THFA were concluded to be 50 mg/kg/day in rats.

Perinatal Nicotine Exposure Eliminates Peak in Nicotinic Acetylcholine Receptor Response in Adolescent Rats

Maternal smoking is a risk factor associated with nicotine abuse, so the effect of perinatal nicotine exposure was studied on the responsiveness to nicotine across adolescence in the rat. Pregnant Sprague-Dawley rats were implanted with s.c. Alzet osmotic minipumps delivering nicotine (L-nicotine hydrogen tartrate, 2 mg/kg/day free base) or vehicle (0.9% saline) on gestational day 7. There was no effect of nicotine on dam weight gain, food consumption, or water consumption or on the number of live pups or weights at the time of birth. Pups were cross-fostered to obtain the following prenatal/postnatal exposure groups: control/control, nicotine/nicotine, nicotine/control, and control/nicotine. On postnatal days 28, 35, 49, and 63, nicotine-stimulated (86)Rb(+) efflux was measured in synaptosomes prepared from the frontal cortex, hippocampus, striatum (STR), and thalamus (THL), using a previously developed method. Significant effects of treatment and concentration were detected in all four brain regions, and significant effects of age were observed in the STR and THL. Significant interactions of age and treatment were observed in each of the four brain regions. Nicotine-stimulated (86)Rb(+) efflux peaked during adolescence in control rats. However, perinatal exposure to nicotine eliminated this peak during adolescence. These results are consistent with recent behavioral and receptor binding results from other laboratories and are the first direct evidence at the cellular level that the nicotinic acetylcholine receptor response varies during adolescence and is affected by perinatal nicotine exposure.

Adverse Effects on Female Development and Reproduction in CD-1 Mice Following Neonatal Exposure to the Phytoestrogen Genistein at Environmentally Relevant Doses

Outbred female CD-1 mice were treated with genistein (Gen), the primary phytoestrogen in soy, by s.c. injections on Neonatal Days 1-5 at doses of 0.5, 5, or 50 mg/kg per day (Gen-0.5, Gen-5, and Gen-50). The day of vaginal opening was observed in mice treated with Gen and compared with controls, and although there were some differences, they were not statistically significant. Gen-treated mice had prolonged estrous cycles with a dose- and age-related increase in severity of abnormal cycles. Females treated with Gen-0.5 or Gen-5 bred to control males at 2, 4, and 6 mo showed statistically significant decreases in the number of live pups over time with increasing dose; at 6 mo, 60% of the females in the Gen-0.5 group and 40% in the Gen-5 group delivered live pups compared with 100% of controls. Mice treated with Gen-50 did not deliver live pups. At 2 mo, >60% of the mice treated with Gen-50 were fertile as determined by uterine implantation sites, but pregnancy was not maintained; pregnancy loss was characterized by fewer, smaller implantation sites and increased reabsorptions. Mice treated with lower doses of Gen had increased numbers of corpora lutea compared with controls, while mice treated with the highest dose had decreased numbers; however, superovulation with eCG/hCG yielded similar numbers of oocytes as controls. Serum levels of progesterone, estradiol, and testosterone were similar between Gen-treated and control mice when measured before puberty and during pregnancy. In summary, neonatal treatment with Gen caused abnormal estrous cycles, altered ovarian function, early reproductive senescence, and subfertility/infertility at environmentally relevant doses.

Effect of selection for litter size and feeding programme on the performance of young rabbit females during rearing and first pregnancy

A total of 166 crossbred young female rabbits were used to study the effect of two types of crossbred does (H1 v. H2, old and current generations, respectively) from the cross of different generations of maternal lines selected for litter size, the use of a feeding programme based on a low energy rearing diet (F) and the presentation of a high-energy dietpre-partum(E) on the performance of young rabbit females until their first parturition and on the main litter traits at first kindling. Perirenal fat was thicker at the age of 3 months for H2 than for H1 does, but this difference disappeared at the first insemination (4·5 months). H2 does had a significantly larger total number and number of live pups at birth (+2·06 live pups) than H1, higher than expected (+1·06). As this greater foetal growth was obtained for a similar energy intake of does, possible differences may exist in partitioning and/or effficiencies of dietary and body energies in favour of foetal growth as the genetic propensity for litter size increased. The use of a low-energy diet significantly reduced the growth of does during the rearing period (−294 g), but they showed a greater compensatory growth during the first 4 weeks of gestation (+79 g) as a consequence of their higher energy intake, without any retardation in their reproductive development. Does receiving diet F until 28th day of gestation showed a significantly greaterpre-partumenergy intake and their number of pups born alive was lower (−1·3 pups). Finally, the litters of females receiving diet Epre-partumand during lactation had lower mortality during the 1st week (26·9 v. 42·9% dead pups) and throughout lactation than those receiving a moderate energy diet.

Evaluation of the Reproductive and Developmental Toxicity of a Fluoroalkylethanol Mixture

The objective of these studies was to evaluate the reproductive and developmental toxicity of a commercial fluoroalkylethanol mixture, which is an intermediate in the production of fluorotelomers. The test substance was administered daily by gavage to Sprague–Dawley rats as a suspension in 0.5% aqueous methylcellulose. In a one-generation reproductive toxicity study, rats (20 per sex per group) were given dosages of 0, 25, 100, or 250 mg kg− 1 day− 1 for a period of 74 days prior to cohabitation, and during mating, gestation, and lactation. Body weights, feed consumption, clinical signs, gross pathology, sperm parameters, estrous cyclicity, and reproductive performance were evaluated for the P1 generation. The F1 offspring were evaluated during the lactation period for growth and survival and given a gross pathology examination at weaning. A subset of the offspring were retained; body weights, feed consumption, clinical signs, and age at onset of vaginal opening and preputial separation were evaluated, and gross pathology was performed on postnatal day 60. In the developmental toxicity study, groups of time-mated Sprague–Dawley female rats were given the test substance as a suspension in 0.5% aqueous methylcellulose at daily dosages of 0, 50, 200, or 500 mg kg− 1 day− 1 by gavage on gestation days 6–20. During the in-life portion of the study, growth parameters and clinical observations were made. On gestation day 21, dams were euthanized, and the thoracic and abdominal viscera were examined. The uterine contents were removed and examined, and fetuses were evaluated for any alterations. In the reproduction study, litter size at birth, number of live pups per litter on day 0 and 4 of lactation, and pup weights during lactation were reduced in groups administered ≥ 100 mg kg− 1 day− 1. No other reproductive parameters were affected. There were no adverse reproductive effects observed at 25 mg kg− 1 day− 1. In the developmental toxicity study, reduced maternal body weight parameters, increased perineal fur staining, and increased fetal skeletal alterations were observed at 500 mg kg− 1 day− 1. There was no maternal or developmental toxicity at 50 or 200 mg kg− 1 day− 1. Under the conditions of the studies, the no-observed adverse effect levels for this mixture were 25 mg kg− 1 day− 1 for subchronic toxicity and reproductive parameters and 200 mg kg− 1 day− 1 for developmental toxicity end points. No functional reproductive or developmental effects were observed at dose levels that did not adversely affect adult animals.

Prostacyclin enhances the implantation and live birth potentials of mouse embryos.

Recently we reported that iloprost, a stable analogue of prostacyclin, enhanced mouse embryo hatching. Here we present a follow-up study to determine whether exposure to iloprost augments the implantation and live birth potentials of mouse embryos. Two-cell embryos (C3B6F1) were harvested 42 h after HCG injection and cultured in medium supplemented with iloprost. After 48 h, the embryos were transferred to 2.5 day pseudopregnant gestational carriers. The number of gestation sacs was counted 72 h later; the number of live pups and the weight of pups and placentae were determined 14 days later. The implantation rate was defined as gestation sac per embryo transferred; the live birth rate was defined as live pup per embryo transferred. The prostacyclin analogue enhanced the implantation rate from 42 to 76% [relative risk 1.84, 95% confidence interval (CI) 1.38-2.43]. The rate of live pups also increased from 28 to 36% (relative risk 1.28, 95% CI 1.04-1.56). The weights of the pups and of the placentae of the two groups were comparable. Prostacyclin enhances the potentials of implantation and live birth of mouse embryos.

Reproductive and developmental toxicity in F 1 Sprague–Dawley male rats exposed to di- n-butyl phthalate in utero and during lactation and determination of its NOAEL

Di- n-butyl phthalate (DBP) is one of the commonly used plasticizers in China. DBP can enter the environment and organisms through various routes and then affect reproductive and developmental processes of the organism and its descendants (mainly affecting male offspring). It is known that animals are sensitive to exposure of DBP in utero and during lactation. In the present study, pregnant rats were treated with different doses of DBP (0, 50, 250, and 500 mg/kg body weight/day) by daily gavage from GD1 to PND21. The developmental condition of F 1 rats and the reproductive system of mature F 1 male rats were monitored. DBP had no obvious effect on pregnant rats; however, it reduced several parameters including birth weight, number of live pups per litter, body weight gain and male anogenital distance. Severe damage to the reproductive system of mature F 1 male rats included testicular atrophy, underdeveloped or absent epididymis, undescended testes, obvious decline of epididymal sperm parameters, total sperm heads per g testis, decrease of organ/body weight ratio of epididymis and prostate, and was observed in the group treated with 250 mg/kg BW/day and higher. These results showed that the male reproductive system was the main target organ of DBP exposure. The NOAEL (no observable adverse effect level) for developmental toxicity of DBP was established based on pup body weight and male reproductive lesions at 50 mg/kg BW/day. Accordingly, the RfD for human exposure to DBP through oral intake was recommended as 500 mg/kg BW/day.

Lack of adverse effects in the F1 offspring maternally exposed to genistein at human intake dose level

Recently there has been growing concern about endocrine disrupters (ED) derived from synthetic and natural chemicals. It has been argued that ED might cause developmental disorders in the next generations of animals and humans; however, this is still unclear. Therefore, we investigated whether maternal exposures to genistein (GEN) during gestation and lactation alter reproductive organs in the F1 offspring compared with those in 17β-estradiol (E2)-maternally exposed F1 offspring. Pregnant Sprague–Dawley rats were treated orally with 0.4 mg/kg, 4.0 mg/kg GEN or 10 μg/kg E2. Maternal or neonatal effects on the number of live pups, implantation sites, sex ratio, anogenital distance, eyelid opening/vaginal opening and body weight of live pups were not altered by GEN or E2. The weights of reproductive organs at the adult stage F1 offspring were not altered by maternal exposure to GEN, except for the ventral prostate. However, the weight of the seminal vesicle was significantly decreased from postnatal day (PND) 21 to PND 70 in E2-treated offspring. Sperm analyses, cell count in seminiferous tubules and follicular development in the ovary were not altered by maternal exposure to GEN. Taken together, these results suggest that maternal exposure of GEN might not have adverse effects on the reproductive organs in the F1 offspring at the human intake dose level.

Normal reproductive organ development in Wistar rats exposed to bisphenol A in the drinking water.

Bisphenol A (BPA) is a chemical used primarily as a monomer in the manufacture of numerous chemical products, such as epoxy resins and polycarbonate. The objective of this study was to evaluate potential effects of BPA on sexual development of male rats and was designed to clarify low-dose observations reported as preliminary results by Sharpe et al. (1996). The protocol for the present study followed the same treatment schedule as reported by Sharpe et al. (1995, 1996), but included more treatment groups, a greater number of animals per group, and a more comprehensive number of reproductive endpoints. Groups of 28 female Han-Wistar albino rats were exposed to drinking water that contained 0, 0.01, 0.1, 1.0, or 10 ppm BPA or 0.1 ppm diethylstilbestrol (DES), 7 days per week, for a total of 10 weeks. Treatment of the females began at 10 weeks of age and continued throughout a 2-week premating period, 2 weeks of mating (to untreated males), 21-22 days of gestation, and 22 days of lactation. Offspring weanling males were given untreated drinking water and maintained until 90 days of age when evaluations were made of various reproductive organs. Consistent with Sharpe et al. (1996) the female offspring were not evaluated. No treatment-related effects on growth or reproductive endpoints were observed in adult females exposed to any concentration of BPA. Similarly, no treatment-related effects were observed on the growth, survival, or reproductive parameters (including testes, prostate and preputial gland weights, sperm count, daily sperm production, or testes histopathology) of male offspring from dams exposed to BPA during gestation and lactation. DES administered in the drinking water at 0. 1 ppm resulted in decreased body weight, body weight change, and food consumption in adult females. In addition, an increase in the duration of gestation and a decrease in the number of pups delivered and number of live pups were also observed in animals exposed to DES. In conclusion, these results do not confirm the previous findings of Sharpe et al. (1996) and show that low doses of BPA had no effects on male sexual development in the rat.

Neuroendocrine and reproductive functions in male mice with targeted disruption of the prolactin gene.

Mice with a targeted disruption (knock-out) of the PRL gene (PRL-KO) were used to study the physiological role of PRL in the control of male neuroendocrine functions related to reproduction. Compared with normal males, PRL-KO mice had significant reductions in median eminence dopamine content, plasma LH levels, LH and FSH secretion in vitro (per mg pituitary), and weights of seminal vesicles and ventral prostate. PRL was not detectable in incubation medium with pituitaries from PRL-KO mice. No alterations were detected in PRL-KO mice in median eminence norepinephrine, plasma testosterone levels, or testosterone release (per mg testis) in vitro with or without LH. No differences were detected in PRL-KO vs. normal male mice in the interval from housing with normal female mice until conception, rate of pregnancy, or the number of live pups per litter. Pituitary weight in PRL-KO mice was increased (1.78 +/- 0.22 vs. 3.35 +/- 0.20 mg; P < 0.001), presumably due to reduced feedback inhibition and hypertrophy and/or hyperplasia of nonfunctional lactotrophs. These results indicate that the absence of PRL reduces pituitary LH release, attenuates median eminence dopaminergic activity, and affects the growth of seminal vesicles and ventral prostate. Although it was previously shown that PRL can repair the reproductive defect in male pituitary dwarf mice, our current results imply that the PRL deficiency alone is not sufficient to cause male infertility, although there are obvious alterations in reproductive neuroendocrine function in PRL-KO males.

Male reproductive tract malformations in rats following gestational and lactational exposure to Di(n-butyl) phthalate: an antiandrogenic mechanism?

Di(n-butyl) phthalate (DBP), a widely used plasticizer suspected of having estrogenic properties, was investigated for its effects on the prenatal and early neonatal development of the reproductive tract. Pregnant CD rats (n = 10) were given DBP at 0, 250, 500, or 750 mg/kg/day (p.o.) throughout pregnancy and lactation until their offspring were at postnatal day 20. Maternal body weights throughout the dosing period were comparable in all groups. At 750 mg/kg/day, the number of live pups per litter at birth was decreased and maternal effects on pregnancy and postimplantation loss are likely to have occurred. Anogenital distance was decreased at birth in the male offspring at 500 and 750 mg/kg/day. The epididymis was absent or underdeveloped in 9, 50, and 71% of adult offspring (100 days old) at 250, 500, and 750 mg/kg/day, respectively, and was associated with testicular atrophy and widespread germ cell loss. Hypospadias occurred in 3, 21, and 43% of males and ectopic or absent testes in 3, 6, and 29% of males at 250, 500, and 750 mg/kg/day, respectively. Absence of prostate gland and seminal vesicles as well as small testes and seminal vesicles were noted at 500 and 750 mg/kg/day. Vaginal opening and estrous cyclicity, both estrogen-dependent events, were not affected in the female offspring, although low incidences of reproductive tract malformations were observed at 500 and 750 mg/kg/day. In the male offspring, DBP produced the same spectrum of effects elicited by the antiandrogen flutamide. Thus, DBP specifically impaired the androgen-dependent development of the male reproductive tract, suggesting that DBP is not estrogenic but antiandrogenic in the rat at these high dose levels. For human risk assessment, determining if this toxicity is metabolite-mediated will be critical, since marked species differences in metabolism exist.