Oral (Drinking Water) Developmental Toxicity Study of Ammonium Perchlorate in Sprague-Dawley Rats

A developmental toxicity study was conducted with ammonium perchlorate (AP) in the drinking water at doses of 0.0, 0.01, 0.1, 1.0, and 30.0 mg/kg-day beginning 14 days before cohabitation and continuing through sacrifice. Twenty-four rats/group were cesarean-sectioned on day of gestation (DG) 21 and fetuses examined for visceral and skeletal alterations. An additional 16 litters/group were sacrificed on DG 21 for maternal and fetal serum TSH, T3, and T4 (thyroid-stimulating hormone, triiodothyronine, and thyroxine) levels and thyroid histopathology. Clinical and necropsy observations, body weights, feed and water consumption, and cesarean-sectioning parameters were comparable among the groups with only delays in ossification observed in the 30 mg/kg-day group. Maternal thyroid weights were increased in the 30.0 mg/kg-day group. Decreased colloid was present in male and female fetal thyroids in the 1.0 and 30.0 mg/kg-day groups. Maternal TSH was increased and T4 was decreased at all levels, and T3 was reduced at 30.0 mg/kg-day. Fetal TSH was increased at 1.0 and 30.0 mg/kg-day, T4 was reduced at 30.0 mg/kg-day, and T3 was decreased at all levels. The maternal no-observable-adverse-effect level (NOAEL) was 1.0 mg/kg-day; exposures of 30.0 mg/kg-day increased absolute and relative maternal thyroid weights and histopathology findings. The developmental NOAEL was 1.0 mg/kg-day; developmental delays in ossification occurred in the 30.0 mg/kg-day group. The colloid depletion in the thyroids and increased TSH and decreased T3 and T4 levels at lower exposures were considered adaptive and not adverse. No adverse effects on development at occurred levels that did not cause maternal toxicity. AP is not a selective developmental toxicant.

Hematopoiesis and Retinoids: Development and Disease

Retinoids function as activating ligands for a class of nuclear receptors that control gene expression programs for a wide range of tissues and organs during embryogenesis and throughout life. Over the years, three sets of observations have spurred interest in the function of retinoids with respect to development and disease of hematopoietic cells. Since the 1920s, epidemiological studies indicated altered hematopoiesis in vitamin A-deficient (VAD) human populations. More recently, the ability of retinoids to affect various aspects of hematopoietic development has been demonstrated in vitro. Finally, it was discovered that the gene encoding a retinoid receptor is a key target for chromosomal translocations that cause acute promyelocytic leukemia (APL). More recent investigations using targeted gene disruptions, VAD animal models, and mouse models of leukemia have continued to shed light on the function of the retinoid pathway in blood cells. It is now clear that retinoids are required for normal hematopoiesis during both yolk sac and fetal liver stages of hematopoiesis, while the pathway has at least modulatory functions for bone marrow derived progenitors. Studies of normal development and APL have provided complementary insight into the molecular control of blood cell differentiation. Here we review the evidence for retinoid requirements in hematopoiesis and also summarize current ideas regarding how this pathway is subverted in leukemia.

Effect of dietary beta-carotene on the early embryonic development and uterine fluid composition of gilts

The role of beta-carotene in reproduction was investigated in gilts assigned to three dietary supplementations: VA (4000 IU vitamin A); VA + VA (4000 IU + 8300 IU); VA + BC (4000 IU + 100 mg beta-carotene) per kg diet for 14 weeks. Gilts were slaughtered at day 12 of gestation. In the VA + BC group, number of corpora lutea was lowest, but the number of embryos was greatest, resulting in a non-significant decreased prenatal mortality (p<0.07). The proportion of less developed spherical and tubular embryos compared with filamentous was greatest in the VA + BC group (p<0.01). No differences were observed for vitamin A and retinal binding protein (RBP) in the uterine fluid. When animals were grouped according to the development of blastocysts, vitamin A and RBP levels were higher in the VA + BC group with only filamentous embryos (p<0.01). This indicates that the supplementation of beta-carotene to gilts might affect embryonic losses possibly because of slower alterations in the uterine environment, resulting in a higher and less variable number of embryos, despite an apparently more heterogeneous development.

Altered expression of genes related to zinc homeostasis in early mouse embryos exposed to di-2-ethylhexyl phthalate

Numerous studies have shown that di-2-ethylhexyl phthalate (DEHP) is teratogenic in animals but the mechanism of developmental toxicity is not well understood. One hypothesis is altered zinc homeostasis. The present study has investigated the effect of DEHP exposure on several key genes in zinc metabolism (MT-I, MT-II, ZnT-1) for early mouse embryos exposed in utero. Time- and dose-dependent effects were examined using expression polymerase chain reaction (PCR) (relative to ACTB) and Western blot analysis of the maternal liver, embryonic brain, and visceral yolk sac at 9 days post-coitus (d.p.c.). Maternal exposure to 800 mg/kg DEHP increased the abundance of MT-I and MT-II transcripts in maternal liver at 3.0, 4.5 and 6.0 h after administration. MT-I and MT-II protein induction was confirmed by Western blot analysis. On the other hand, this exposure down-regulated both transcripts (MT-I, MT-II), as well as transcripts for a zinc transporter (ZnT-1), in the embryonic brain, but not the visceral yolk sac. To examine dose-response relationships, the experiment was repeated for DEHP exposures of 50, 200 and 800 mg/kg. The effect to MT-I and MT-II expression in the maternal liver became significant at the 200 mg/kg dose level. The contrasting effect to MT-I, MT-II and ZnT-1 expression in the embryo was also dose-dependent, and a benchmark computation for the dose resulting in a 5% change in the mean (BMD5) was estimated as 11.6 mg/kg for MT-I, 8.9 mg/kg for MT-II, and 6.6 mg/kg for ZnT-1. We conclude that DEHP exposure to pregnant dams at reasonably low levels during organogenesis stages can alter the expression of several key genes in embryonic zinc homeostasis.

A chronic low dose infusion of insulin-like growth factor I alters placental function but does not affect fetal growth

Knowledge of the anabolic effects of insulin-like growth factor I (IGF-I) on fetal growth and feto-placental metabolism are derived from studies using large doses of IGF-I. Low doses of enteral IGF-I have trophic effects on the fetal gut, but there are no data on the effects of systemic low doses of IGF-I on fetal growth and feto-placental metabolism. We therefore compared the effects of a chronic infusion of low dose IGF-I (50 microg day(-1), n = 7) with vehicle-infused controls (n = 7) on fetal growth, metabolism and placental transfer capacity in the chronically instrumented late gestation ovine fetus (121-132 days of gestation; term = 145 days). Insulin-like growth factor I infusion did not affect fetal growth or the size of individual organs, including liver, spleen and bone. Placental morphology was altered, and placental clearances of 3-O-[methyl-3H]D-glucose (a non-metabolizable glucose analogue) and [methyl(14C)]aminoisobutyric acid (a non-metabolizable analogue of amino acids utilizing the system A transporter), were reduced in IGF-I-treated fetuses (P < 0.05 v. control). However, fetal and placental metabolite uptake was not significantly different between groups. We conclude that, despite altering placental transfer capacity and morphology, a chronic low dose infusion of IGF-I does not alter fetal growth or metabolism.

The effect of extracellular matrix molecules on mouse preimplantation embryo development in vitro

The extracellular matrix (ECM) molecules, laminin (LN), chondroitin sulfate (CS), fibronectin (FN), hyaluronic acid (HA), mucin (MUC) and heparan sulfate proteoglycan (HS), were investigated as supplements to culture medium to improve the in vitro development of mouse 1-cell zygotes to blastocysts. Development was also compared with that in medium supplemented with bovine serum albumin (BSA) to determine the potential for ECM molecules as suitable alternatives to serum albumin in culture medium. Supplementation of sequential culture media with LN at all concentrations examined failed to result in more than 70% of zygotes developing to blastocysts; therefore, LN was considered unsuitable as a replacement for BSA and was not examined further. The optimal concentration of the remaining ECM molecules was used to supplement sequential culture media and the effect on blastocyst quality was assessed by determining the differential cell numbers of blastocysts grown in BSA-supplemented medium. Development to blastocyst was similar, regardless of the macromolecule used. The number of inner cell mass cells was significantly higher in HS-supplemented medium compared with controls. Trophectoderm cell numbers were similar to control values for all ECM molecules examined except CS for which there were fewer trophectoderm cells. It is concluded that ECM molecules, FN, HA, MUC and HS may be used as substitutes for serum protein supplementation of culture media EG0/G2 for mouse preimplantation embryo development. Heparan sulfate proteoglycan increases inner cell mass numbers and this may be due to interactions with the growth factors fibroblast growth factor 4 (FGF-4) and granulocyte-macrophage colony-stimulating factor.

Effects of restraint stress in gestation: implications for rodent developmental toxicology studies

Restraint has been used as a procedure to study the effects of stress on gestation outcome in rodents. The effects of restraint could potentially be used as a model for the impact of general stress produced by high doses of toxicants and other interventions. In mice, restraint in the peri-implantation period leads to implantation failure, and restraint at appropriate times in organogenesis produces cleft palate, supernumerary ribs, and resorption. In rats, there is some evidence for an association with restraint for implantation failure, but not for the morphological anomalies. Restraint in late gestation alters adult sexual behavior of male rat offspring, but consequences for their fertility are not known. Intrauterine growth retardation is not commonly associated with gestational restraint. In the few studies where they have been directly compared, different restraint procedures produced graded, qualitatively different, or no effects. Adrenocortical hormones have been implicated as mediating the effect of restraint on cleft palate, but not on supernumerary ribs, implantation failure, or sexual differentiation. Given the variety of restraint procedures and the varying species-dependent consequences, it is not possible to infer a generalizable pattern of developmental effects due to gestational stress from the restraint literature. As an alternative approach, contemporary methods in gene expression and developmental biology could profitably be applied to understanding different patterns of stress-mediated effects of toxicant exposures on intrauterine development.

Fetal ADH2*3, maternal alcohol consumption, and fetal growth

There is some evidence suggesting the allele for alcohol dehydrogenase 2*3 (ADH2*3) is associated with a protective effect against alcohol-related intrauterine growth retardation (IUGR). This study was conducted to explore the affect of the ADH2*3 allele on fetal growth. Bloodspots (n = 1016) belonging to individual infants of a subgroup of the Baltimore-Washington Infant Study (BWIS) were assayed for the presence of the ADH2*3 allele by a polymerase chain reaction (PCR)-based method. Infants genotyped for ADH2*3 were those for whom bloodspots were identified and obtained from the Maryland Newborn Screening Program. The effect of ADH2*3 and maternal alcohol consumption on intrauterine growth was explored by multivariable linear regression analysis. Twenty-six percent of the 306 blood spots belonging to African-American infants were positive for ADH2*3 (4% were homozygous and 22% were heterozygous). Only a small percentage of bloodspots for Caucasian (1.3%) were positive for the ADH2*3 allele. Consequently, further analysis concentrated on gene-exposure interactions for African-American infants. It was found that the incidence of being small-for-gestation-age (SGA) was lower for ADH2*3-positive infants (2.5% versus 8.8%; p = .08). SGA infants had elevated odds for being ADH2*3 negative (OR: 3.15, 95% C.I.: 0.70-14.26) and for being born to mothers that consumed alcohol during pregnancy (OR: 2.31, 95% C.I.: 0.77-6.91). A negative trend between maternal alcohol consumption and mean offspring birthweight was found; however, ADH2*3 did not have a significant impact on mean birthweight for infants born to mothers that drank during pregnancy. These results could be interpreted as possible support for the hypothesis that ADH2 genotype in the infant may impact risk for alcohol-related IUGR. However, this study has limitations in that it is a "nested study of convenience" and involves a relatively small number of infants born to mothers reporting moderate to heavy alcohol use during pregnancy.

Effects of thalidomide on reproductive function and early embryonic development in male and female New Zealand white rabbits

BACKGROUND

The present work was performed to determine the effect of thalidomide exposure on reproductive function and early embryonic development.

METHODS

Twenty-five female New Zealand White rabbits were orally gavaged with 0, 10, 50, or 100 mg/kg/day thalidomide 14 days prior to mating through to gestation day 7 for a total of 22 days. Treated females were Caesarean-sectioned approximately 29 days after the date of attempted mating. Following mating with treated females, male rabbits (25/dose) were gavaged with 0, 30, 150, or 500 mg/kg/day beginning 14 days prior to mating with a group of untreated females (25/dose). Doses were administered through mating until the day before sacrifice for a minimum of 56 days. Untreated females were Caesarean-sectioned 29 days after the last attempted mating. Comprehensive necropsy and histopathology of the reproductive system were performed.

RESULTS

Treated females had reduction in body weight gain during gestation. Mating and pregnancy parameters were unaffected by thalidomide. At 100 m/kg, litter averages for corpora lutea, implantations, litter sizes, does with viable fetuses and live fetuses decreased and the number of early resorptions, does with any resorptions, does with all conceptuses resorbed, and the percent resorbed conceptuses per litter increased. The number of early resorptions, the average number of early resorptions per litter, and the percent resorbed conceptuses per litter increased at 10 and 50 mg/kg. There were no thalidomide-related external fetal malformations. Mating and fertility in male rabbits were unaffected by thalidomide. There was an increased incidence of flaccid testes at 150 and 500 mg/kg and of bilateral small testes in all treated groups. At 500 mg/kg, there was degeneration of the germinal epithelium of the testicles with an increase in multinucleated giant cells in seminiferous tubule and a loss of round and elongating spermatids.

CONCLUSIONS

Thalidomide had no adverse effects on mating and fertility in male and female rabbits dosed up to 500 and 100 mg/kg/day, respectively, for 14 days prior to mating. After 56 day of dosing, histopathologic changes with no associated sperm abnormalities were observed in the testicles. Embryonic development NOAEL for treated females mated to untreated males was <10 mg/kg. Corresponding fertility NOAEL for treated males mated to untreated females was 500 mg/kg.

Inhibition of ossification in vivo and differentiation of osteoblasts in vitro by tributyltin

Tributyltin is ubiquitous in the environment and an endocrine disruptor for many wildlife species. However, minimal information is available regarding the effect of this chemical on bone formation. When tributyltin chloride (TBT) (1mg/kg body weight) was administered subcutaneously to pregnant mice at 10, 12, and 14 days post coitus (dpc), fetuses at 17.5 days post coitus revealed the inhibition of calcification of supraoccipital bone. In contrast, 1mg/kg body weight monobutyltin trichloride (MBT) did not affect the fetal skeleton. Therefore, we examined the effects of TBT and its metabolites (dibutyltin dichloride, DBT, and MBT) on bone metabolism using rat calvarial osteoblast-like cells (ROB cells). The viability of ROB cells was not affected by the exposure of the cells to 10(-10) to 10(-7)M TBT. However, TBT reduced the activity of alkaline phosphatase (ALPase) and the rate of deposition of calcium of ROB cells. In addition, the expression levels of mRNA for ALPase and osteocalcin, which are markers of osteoblastic differentiation, were depressed by the treatment with TBT. TBT inhibited ALPase activity and the deposition of calcium to a greater extent than did DBT. MBT had no effect on the osteoblast differentiation of ROB cells. Tributyltin is known to inhibit the activity of aromatase. However, the aromatase inhibitor aminoglutethimide did not reproduce the inhibitory effects of TBT on osteoblast differentiation. Our findings indicate that TBT might have critical effects on the formation of bone both in vivo and in vitro although its action mechanism is not clarified.

A prospective study of pregravid oral contraceptive use in relation to fetal growth

OBJECTIVE

Because oral contraceptives are so widely used, any health consequences may have substantial public health implications. Whether pregravid oral contraceptives could affect subsequent pregnancies has not been adequately studied. The study objectives were to examine whether pregravid oral contraceptive use affects fetal growth and pregnancy hormone levels.

DESIGN

A prospective study of pregnant women followed through pregnancy.

SETTING

A major teaching hospital in Boston, USA.

POPULATION

Two hundred and sixty Caucasian pregnant women, with a mean age of 31, and a parity of no more than two. Seventy-nine percent of the women were pregravid oral contraceptive users.

METHODS

Exposure and covariate data were collected through structured questionnaires. Blood was drawn for hormonal analysis during the 16th and 27th gestational week. Information on pregravid oral contraceptive use included duration and recency of use, and oral contraceptive formulation. Multivariate regression models were used to examine the effect of pregravid oral contraceptive use on birth outcomes and the studied pregnancy hormones.

MAIN OUTCOME MEASURES

Birthweight, placental weight, gestational age, pregnancy hormone levels of oestriol and progesterone at 16th and 27th gestational week.

RESULTS

Adjusting for confounders, pregravid oral contraceptive use increased birthweight (mean difference =+207.3 g, 95% CI =+77.6 to +337.1) and placental weight (mean difference =+64.9 g, 95% CI =+13.0 to +116.9) compared with never use. Women with prior oral contraceptive use had higher levels of serum progesterone (P= 0.002) and oestriol (P= 0.12) at the 27th gestational week measurement. The effect on birthweight, placental weight and hormones was stronger among those using oral contraceptives in the previous year and those using a high progestin/high oestrogen potency preparation.

CONCLUSIONS

Pregravid oral contraceptive use is positively associated with fetal growth, and this effect may be mediated through oestriol and progesterone.

Effect of prematuration, meiosis activating sterol and enriched maturation medium on the nuclear maturation and competence to development of calf oocytes

New strategies were proposed to improve the developmental competence of calf oocytes through in vitro technologies. Cumulus-oocyte complexes were first prematured for 24 h in the presence of meiosis inhibitors. Both Roscovitine alone (50 microM) or in combination with Butyrolactone-I (12.5 microM Rosco+6.25 microM BL-I) prevented the progression of meiosis. Their effect on nuclear maturation was reversible after a further 17 or 24 h maturation step. However, a dramatic decrease in embryo development was observed after fertilization (abattoir oocytes: 4-9% blastocyst rate versus 14-17% for control embryos). Similar results were obtained with oocytes collected by Ovum Pick Up from living donors. No pregnancy was obtained after single transfer of two blastocysts obtained from prematured oocytes (0/2 versus 4/12 for control embryos). Adding low concentrations (1, 3 or 10 microM) of follicular fluid-meiosis activating sterol (FF-MAS) during the maturation step had a beneficial effect on nuclear maturation (73-86% metaphase II versus 58% for control oocytes). However, subsequent embryo development was not improved. Enriching the maturation medium, namely with hormones, growth factors and precursors of glutathione, induced a sixfold increase in glutathione in the oocyte and had a beneficial effect on embryo development (38% increase in blastocyst rate). In conclusion, in opposition to the results reported with adult oocytes, prematuring calf oocytes had a negative impact on their developmental potential. Although FF-MAS improved nuclear maturation, its addition in the maturation medium did not increase embryo development. However, enriching the maturation medium had a positive effect on embryo development, indicating that cytoplasmic maturation was improved.

Promoting effect of amino acids added to a chemically defined medium on blastocyst formation and blastomere proliferation of bovine embryos cultured in vitro

This study was conducted to elucidate the role of amino acids added singly or in groups to a chemically defined culture medium in blastocyst formation and blastomere proliferation of bovine embryos. Embryos were generated by in vitro fertilization, and blastocyst formation and hatching, and blastomere number of blastocysts were subsequently monitored after the culture of embryos in synthetic oviduct fluid medium (SOFM). First, one of four non-essential amino acids (asparagine, aspartate, glutamate or serine) was added to SOFM and, compared with no addition, a significant (P <0.05) increase in blastocyst formation was found after the addition of asparagine, aspartate, or glutamate (35-42% versus 22%). Second, one of four essential amino acids (arginine, cystine, isoleucine or leucine) was added and arginine or isoleucine greatly improved blastocyst formation (30-36% versus 16%). Third, the addition of five stimulatory amino acids (aspartate, asparagine, glutamate, arginine and isoleucine) to SOFM significantly improved blastocyst formation compared with no addition (12% versus 21%) and such value was similar to that obtained after the addition of 19 amino acids consisting of MEM amino acid solutions (21-27%). However, five amino acids yielded fewer hatched blastocysts than 19 amino acids. Finally, although five amino acids yielded more cell number of blastocysts than no addition (93 versus 74 cells per blastocyst), it was lower than that from 19 amino acids (131 cells per blastocyst). In conclusion, either single or combined addition of asparagine, aspartate, glutamate, arginine and isoleucine stimulated blastocyst formation, while other amino acids might be necessary for further stimulating blastomere proliferation and blastocyst hatching.

Choline availability during embryonic development alters progenitor cell mitosis in developing mouse hippocampus

Previously, we reported that dietary choline influences development of the hippocampus in fetal rat brain. It is important to know whether similar effects of choline occur in developing fetal mouse brain because interesting new experimental approaches are now available using several transgenic mouse models. Timed-pregnant mice were fed choline-supplemented (CS), control (CT) or choline-deficient (CD) AIN-76 diet from embryonic day 12 to 17 (E12-17). Fetuses from CD dams had diminished concentrations of phosphocholine and phosphatidylcholine in their brains compared with CT or CS fetuses (P < 0.05). When we analyzed fetal hippocampus on day E17 for cells with mitotic phase-specific expression of phosphorylated histone H3, we detected fewer labeled cells at the ventricular surface of the ventricular zone in the CD group (14.8 +/- 1.9) compared with the CT (30.7 +/- 1.9) or CS (36.6 +/- 2.6) group (P < 0.05). At the same time, we detected more apoptotic cells in E17 hippocampus using morphology in the CD group (11.8 +/- 1.4) than in CT (5.6 +/- 0.6) or CS (4.2 +/- 0.7) group (P < 0.05). This was confirmed using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin anti-digoxigenin fluorescein conjugate antibody nick end-labeling (TUNEL) and activated caspase-3 immunoreactivity. We conclude that the dietary availability of choline to the mouse dam influences progenitor cell proliferation and apoptosis in the fetal brain.

Vitamin a requirement for early cardiovascular morphogenesis specification in the vertebrate embryo: insights from the avian embryo

Vitamin A is required throughout the life cycle, including crucial stages of embryonic and fetal development. With the identification of retinoic acid-specific nuclear transcription factors, the retinoid receptors, considerable advances have been made in understanding the molecular function of vitamin A. The requirement for vitamin A during early embryogenesis has successfully been examined in the vitamin A-deficient avian embryo during neurulation, when in the vertebrates crucial developmental decisions take place. These studies revealed that retinoic acid is essential during these early stages of embryogenesis for the initiation of organogenesis (i.e., formation of the heart). If retinoic acid is not present at this time, abnormal development ensues, leading to early embryonic death. Though the initial insult of the absence of vitamin A appears to be on the specification of cardiovascular tissues, subsequently all development is adversely affected and the embryo dies. Molecular and functional studies revealed that retinoic acid regulates the expression of the cardiogenic transcription factor GATA-4 and several heart asymmetry genes, which explains why the heart position is random in vitamin A-deficient quail embryos. During the crucial retinoic acid-requiring developmental window, retinoic acid transduces its signals to genes for heart morphogenesis via the receptors RARalpha2, RARgamma, and RXRalpha. Elucidation of the function of vitamin A during early embryonic development may lead to a better understanding of the cardiovascular birth defects prevalent in the Western world.

Prolonged oral treatment with an essential amino acid L-leucine does not affect female reproductive function and embryo-fetal development in rats

L-leucine, an essential amino acid, is one of the most popular ingredients in dietary supplements. To investigate a possibility of its embryo-fetal toxicity in rats, 11- to 12-week old dams were orally administered an aqueous solution of L-leucine at doses of 300 or 1000 mg/kg body weight on gestational days 7-17. Body weight and feed intake was evaluated throughout the whole course of pregnancy (days 0-20). L-Leucine did not influence body weight, but at a dose of 1000 mg/kg, slightly enhanced feed intake on days 14 and 18 of pregnancy. Caesarean section (day 20) revealed no influences on the litter size and weight of live-born fetuses, the number of corpora lutea, implantation index or the quality of placenta, and the minor increase in feed intake was considered irrelevant to the pregnancy outcomes. Fetuses were evaluated in a battery of external, visceral and skeletal examinations. No effects of L-leucine on gender ratio and external abnormalities, and no significant treatment-related variations in visceral and skeletal pathologies were observed. These results suggested that L-leucine, administered orally during organogenesis at doses up to 1000 mg/kg body weight, did not affect the outcome of pregnancy and did not cause fetotoxicity in rats.

Differential effects of maternal and fetal betamethasone injections in late-gestation fetal sheep

OBJECTIVE

To determine the effects of single or repeated intramuscular injections of betamethasone, given maternally or directly to the fetus, on chronically catheterized, late-gestation fetal sheep.

METHODS

Fetal or maternal sheep received either repeated intramuscular injections of betamethasone (0.5 mg/kg body weight at 104, 111, and 118 days' gestation), single betamethasone injection (at 104 days' gestation, followed by saline at 111 and 118 days' gestation), or repeated saline injections; n = 6 or 7 per group. At approximately 130 days' gestation fetuses were catheterized for serial measurements of heart rate, arterial pressure, blood gases, metabolites, and electrolytes.

RESULTS

Repeated maternal betamethasone injections reduced birth weight (P =.03) without fetal hypoxemia or hypoglycemia. Circulating fetal calcium and lactate concentrations were reduced (P =.002 and P =.014, respectively) by repeated maternal betamethasone only. Fetal hematocrit tended to be lower after fetal (P =.3) and maternal (P =.07) betamethasone.

CONCLUSION

Growth restriction caused by repeated maternal betamethasone treatments is not due to overt chronic placental insufficiency but may be caused by alterations in hormonal mediators of fetal growth or impairment of placental transport of specific nutrients.

Valproic acid teratogenicity: a toxicogenomics approach

Embryonic development is a highly coordinated set of processes that depend on hierarchies of signaling and gene regulatory networks, and the disruption of such networks may underlie many cases of chemically induced birth defects. The antiepileptic drug valproic acid (VPA) is a potent inducer of neural tube defects (NTDs) in human and mouse embryos. As with many other developmental toxicants however, the mechanism of VPA teratogenicity is unknown. Using microarray analysis, we compared the global gene expression responses to VPA in mouse embryos during the critical stages of teratogen action in vivo with those in cultured P19 embryocarcinoma cells in vitro. Among the identified VPA-responsive genes, some have been associated previously with NTDs or VPA effects [vinculin, metallothioneins 1 and 2 (Mt1, Mt2), keratin 1-18 (Krt1-18)], whereas others provide novel putative VPA targets, some of which are associated with processes relevant to neural tube formation and closure [transgelin 2 (Tagln2), thyroid hormone receptor interacting protein 6, galectin-1 (Lgals1), inhibitor of DNA binding 1 (Idb1), fatty acid synthase (Fasn), annexins A5 and A11 (Anxa5, Anxa11)], or with VPA effects or known molecular actions of VPA (Lgals1, Mt1, Mt2, Id1, Fasn, Anxa5, Anxa11, Krt1-18). A subset of genes with a transcriptional response to VPA that is similar in embryos and the cell model can be evaluated as potential biomarkers for VPA-induced teratogenicity that could be exploited directly in P19 cell-based in vitro assays. As several of the identified genes may be activated or repressed through a pathway of histone deacetylase (HDAC) inhibition and specificity protein 1 activation, our data support a role of HDAC as an important molecular target of VPA action in vivo.

Latanoprost exposure in pregnancy

PURPOSE

To observe pregnancies exposed to latanoprost, a prostaglandin analog administered in the treatment of glaucoma. Its prescription is limited in pregnancy, because reproduction studies in animals report a high incidence of abortion and human investigations are not adequate. As a consequence it is classified as category C drug according to the United States Food and Drug Administration's use-in-pregnancy ratings.

DESIGN

Observational study.

METHODS

We collected data, referred to our Teratology Information Service, relative to latanoprost exposure in pregnancy. We followed by phone interviews women treated with latanoprost during the first trimester, and we evaluated whether there had been any adverse effects on the fetus.

RESULTS

Eleven cases of latanoprost exposure in pregnancy were referred to our Teratology Information Service. One case was lost to follow-up, and one case was complicated by miscarriage. Nine cases had a complete follow-up without congenital anomalies.

CONCLUSIONS

Our series is too small to perform statistical significance; however, we found no evidence of adverse effects of latanoprost on pregnancy or neonatal outcomes.

Effects of oxygen tension in the gas atmosphere during in vitro maturation, in vitro fertilization and in vitro culture on the efficiency of in vitro production of mouse embryos

Effects of oxygen (O2) tension in the gas atmosphere during in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC) on the efficiency of in vitro production of mouse embryos were examined. Mouse oocytes recovered from large antral follicles were subjected to IVM in Waymouth medium for 15, 16 and 17 hr under 5 or 20% O2 and then subjected to IVF and IVC under 5 or 20% O2 tension. Lowering the O2 tension in the gas atmosphere for IVM from 20 to 5% improved the cleavage rate after IVF when the oocytes were subjected to IVM for 15 hr; however, no improvement in the cleavage rate was observed when the culture period for IVM was extended to 16 and 17 hr. Lowering the O2 tension to 5% for IVM and IVC improved the development of the cleaved oocytes to the blastocyst stage, regardless of the culture period for IVM. However, the O2 tension for IVF had no remarkable effect on the subsequent embryonic development. These results demonstrate that 5% O2 is superior to 20% O2 for IVM and IVC, and suggest that 20% O2 for IVM may delay oocyte maturation and/or the acquisition of fertilizability and impair the developmental competence of oocytes.

Consequences of Elevated Homocysteine During Embryonic Development and Possible Modes of Action

Elevated maternal homocysteine (Hcys) is a well-established risk factor for embryonic toxicity and the development of congenital defects, particularly neural tube closure defects and neurocristopathies. The mechanisms responsible are unclear but early work has focused on the role of folate metabolism because these defects are greatly reduced by folate supplementation. As a consequence, elevated Hcys is often looked upon as being an indirect consequence of faulty folate metabolism, although more recent studies show Hcys may act directly as a teratogen. Because Hcys is at the crossroads of protein and DNA metabolism, has a propensity to chemically modify proteins directly, can generate free radicals, and even perturb ligand binding to certain receptors, the developmental processes Hcys can potentially disturb are enumerable. But in recent years, investigators have begun identifying cellular and molecular targets for the direct action of Hcys. While elevating Hcys can alter a myriad of basic cellular activities needed for normal development, our current understanding as to the specific etiological mechanisms responsible for congenital defects is very speculative. Here we provide an overview of what is currently known regarding the toxicity and teratogenicity of elevated Hcys during embryonic development, paying particular attention to neural tube and neural crest cell morphogenesis.

Effect of demecolcine and nocodazole on the efficiency of chemically assisted removal of chromosomes and the developmental potential of nuclear transferred porcine oocytes

Brief treatment of metaphase II (MII) stage porcine oocytes with 0.4 microg/mL demecolcine in the presence of 0.05 M sucrose produces a membrane protrusion that contains a condensed chromosome mass. The present study examined the optimal conditions for demecolcine and nocodazole treatment in chemically assisted removal of chromosomes. When matured oocytes were treated with 0.1-0.4 microg/mL demecolcine for 60 min or with 0.4 microg/mL demecolcine for 30 min or 3 microg/mL nocodazole for 30 or 60 min, more than 70% of oocytes had a membrane protrusion containing condensed chromosomes were located. There was no difference in the in vitro developmental potential of enucleated oocytes assisted by 0.1 and 0.4 microg/mL demecolcine or 3 microg/mL nocodazole that received porcine somatic cells. After transfer to 10 recipients, however, two of six recipients that received demecolcine-treated enucleated eggs produced four healthy cloned piglets, but none of the four recipients of nocodazole-treated enucleated eggs produced piglets. Further studies are required to increase the successful development to term because the proportion of live piglets was low (4/2, 672, 0.15%).

Ruta graveolens aqueous extract retards mouse preimplantation embryo development

This work was undertaken to examine possible embryotoxicity of Ruta graveolens (rue), a plant used by indigenous communities for the purposes of therapeutic and fertility regulation. Superovulated mice were mated and isolated after copulation. They were given aqueous extract of R. graveolens (5, 10, and 20% w/v) or plain water (control) orally for 4 days. Ninety-eight hours post-human chorionic gonadotrophin (hCG), embryos were flushed from oviducts and uterine horns to assess their state of development and extent of embryo transport. Ingestion of rue at 10 and 20% resulted in a high proportion of abnormal embryos (36.7 and 63.6%, respectively, P<0.05). Cell number was diminished (P<0.01) and embryo transport was slightly delayed in the highest dose group. These findings demonstrate that oral administration of R. graveolens extract can interfere with preimplantation development and embryo transport.

Prostacyclin enhances embryo hatching but not sperm motility

BACKGROUND

Recently we discovered that the human oviduct synthesizes abundant prostacyclin (PGI(2)). Gene knock-out studies suggest that PGI(2) is essential to endometrial decidualization, but the effects of PGI(2) on sperm and embryos have not been reported.

METHODS

The effects of PGI(2) on human sperm were analysed by a computer-assisted semen analysis system. The effects of PGI(2) on mouse embryos were examined based on the rates of complete hatching. The expression of PGI(2) receptor (IP) was evaluated by Western blot analysis and immunohistochemistry. The binding of PGI(2) to embryos was confirmed by radioligand binding assay. Finally, cAMP levels were assessed in PGI(2)-challenged embryos.

RESULTS

Iloprost (a stable PGI(2) analogue) did not affect the motility or the overnight survivability of human sperm. Western blot analysis did not detect IP in the sperm plasma membrane. In contrast, the hatching of mouse embryos was enhanced by iloprost (ED(50) 6.7 nmol/l). Exposure to iloprost during 8-cell to morulae or morulae to early blastocyst stages was critical to enhanced hatching. This coincided with the developmental stage-specific expression of IP. Although iloprost bound to blastocysts, it did not significantly increase cAMP.

CONCLUSION

PGI(2) enhanced the hatching of mouse embryos but not the motility of human sperm.

Role of endogenous reverse transcriptase in murine early embryo development

We report that a reverse transcriptase (RT) activity is present in early cleavage stage embryos as determined by a Polymerase chain reaction (PCR)-based detection assay. In an attempt to establish whether this activity plays a role in early embryonic development, we have blocked the endogenous RT by two independent approaches: (1) embryos were exposed to nevirapine, a highly specific nonnucleoside inhibitor of RT activity; (2) anti-RT antibody was microinjected into the nucleus of one blastomere of 2-cell embryos. When embryos were exposed to nevirapine in the developmental window between late 1-cell and 4-cell stages, development was arrested before the blastocyst stage. In contrast, development was not affected when embryos were exposed to nevirapine after the eight-cell stage. Developmental arrest was also induced when anti-RT antibody was microinjected in one blastomere of 2-cell embryos. Analysis of gene expression by RT-PCR in nevirapine-arrested 2-cell embryos revealed an extensive and specific reprogramming of gene expression, involving both developmentally regulated and constitutively expressed genes, compared to control embryos. These results support the conclusion that an endogenous RT activity is required in mouse early embryogenesis specifically between the late 1-cell and the 4-cell stage.

Experimental studies on reproductive toxicologic effects of lamotrigine in mice

BACKGROUND

Virtually all antiepileptic drugs (AED) tested so far have been found to be teratogenic. The second generation AED possess a number of therapeutic advantages over the older ones. There are, however, very little data on their effects on embryonic development. A recent report suggests that lamotrigine (LTG) can be teratogenic to human fetuses. With only a few cases of prenatal exposure to LTG in the record, however, it has not been possible to establish a recognizable pattern of malformations in the infants of LTG-treated mothers.

OBJECTIVES

The objectives of the present study were to evaluate the reproductive toxic effects of LTG .

RESULTS

Single (50-200 mg/kg) or multiple doses (25, 50, 75 mg/kg) of LTG were administered by intraperitoneal (i.p.) injection (note that the therapeutic administration is oral) to groups of TO mice on gestation day (GD) 7 or 8. Fetuses were collected on GD 18. Maternal toxic effects including a dose-related mortality, a high incidence of abortion, embryo lethality, congenital malformations and intrauterine growth retardation (IUGR) were observed in the LTG-treated group. Administration of LTG in multiple low doses resulted in a better maternal survival and increased incidence of embryonic resorption and malformations with increasing dose; IUGR was significant but not dose-dependent. The malformations characteristic of the LTG multiple low dose group fetuses included maxillary-mandibular hypoplasia, exencephaly, cleft palate, median facial cleft, urogenital anomalies and varying degrees of caudal regression. Skeletal malformations and developmental delay of the skeleton were observed both in single and multiple dose groups.

CONCLUSIONS

The results of this study indicate that LTG administered i.p. at high doses can induce intrauterine growth retardation and at low multiple doses causes a dose-dependent increase in embryonic resorption, craniofacial and caudal malformations as well as maternal toxicity in the mouse. Previous studies in other laboratories have used oral route of exposure and concluded that there are no teratogenic effects of LTG at dose levels that are not maternally toxic.

Triphenyltin as a potential human endocrine disruptor

Organotin compounds have been implicated as reproductive toxicants and endocrine disruptors primarily through studies in aquatic organisms, with little information available in mammals. Among the organotins, aryltins have been less studied than alkyltins. Extensive data is available on mammalian developmental and reproductive toxicity of one aryltin compound, triphenyltin (TPT), from toxicity studies conducted in connection with the registration of triphenyltin hydroxide (TPTH) as a pesticide and supporting publications from the open literature. Indications of adverse functional and morphological effects on the reproductive tract of rats were reported in a dose range of 1.4-20 mg/kg/d. Gonadal histopathology (both ovaries and testes) and infertility were affected at the higher doses, while reproductive-tract cancer, smaller litter sizes, and reproductive organ weights were affected at the lower end of the dose range. In vitro studies indicate that TPT can directly activate androgen receptor-mediated transcription and inhibit enzymes that are involved in steroid hormone metabolism. These data suggest that the aryltin TPT can be active as a reproductive toxicant in mammals and may be a human endocrine disruptor.

Involvement of p53 in 1-β-d-arabinofuranosylcytosine-induced rat fetal brain lesions

1-beta-D-Arabinofuranosylcytosine (Ara-C), a cytidine analogue cytotoxic to proliferating cells, has a teratogenic effect in the brain of experimental animals and causes neural cell apoptosis in vitro and in vivo. In the present study, pregnant rats were injected with Ara-C on Day 13 of gestation and the fetal brain was collected from 1 to 48 h after treatment. Histopathological examinations revealed marked induction of apoptotic cell death and decrease of mitosis in neuroepithelial cells in the brain of Ara-C-treated fetus, and these changes were most prominent from 9 to 12 h. Expression of p53 protein, which mediates apoptosis and cell cycle arrest after DNA damage, was elevated remarkably and peaked at 3 h. p21, a cyclin-dependent kinase inhibitor responsible for p53-mediated cell cycle arrest, showed intense overexpression in protein and mRNA levels following the increase of p53 protein. The mRNA expressions of other p53 transcriptional target genes, bax, cyclinG1, and fas, also significantly increased and peaked at around 9 h. In conclusion, prenatal treatment of Ara-C is thought to induce apoptosis and inhibition of cell proliferation mediated by p53 and its target genes in the fetal brain.

Association of in utero organophosphate pesticide exposure and fetal growth and length of gestation in an agricultural population

Although pesticide use is widespread, little is known about potential adverse health effects of in utero exposure. We investigated the effects of organophosphate pesticide exposure during pregnancy on fetal growth and gestational duration in a cohort of low-income, Latina women living in an agricultural community in the Salinas Valley, California. We measured nonspecific metabolites of organophosphate pesticides (dimethyl and diethyl phosphates) and metabolites specific to malathion (malathion dicarboxylic acid), chlorpyrifos [O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphoro-thioate], and parathion (4-nitrophenol) in maternal urine collected twice during pregnancy. We also measured levels of cholinesterase in whole blood and butyryl cholinesterase in plasma in maternal and umbilical cord blood. We failed to demonstrate an adverse relationship between fetal growth and any measure of in utero organophosphate pesticide exposure. In fact, we found increases in body length and head circumference associated with some exposure measures. However, we did find decreases in gestational duration associated with two measures of in utero pesticide exposure: urinary dimethyl phosphate metabolites [beta(adjusted) = -0.41 weeks per log10 unit increase; 95% confidence interval (CI), -0.75 -- -0.02; p = 0.02], which reflect exposure to dimethyl organophosphate compounds such as malathion, and umbilical cord cholinesterase (beta(adjusted) = 0.34 weeks per unit increase; 95% CI, 0.13-0.55; p = 0.001). Shortened gestational duration was most clearly related to increasing exposure levels in the latter part of pregnancy. These associations with gestational age may be biologically plausible given that organophosphate pesticides depress cholinesterase and acetylcholine stimulates contraction of the uterus. However, despite these observed associations, the rate of preterm delivery in this population (6.4%) was lower than in a U.S. reference population.

Prenatal insecticide exposures and birth weight and length among an urban minority cohort

We reported previously that insecticide exposures were widespread among minority women in New York City during pregnancy and that levels of the organophosphate chlorpyrifos in umbilical cord plasma were inversely associated with birth weight and length. Here we expand analyses to include additional insecticides (the organophosphate diazinon and the carbamate propoxur), a larger sample size (n = 314 mother-newborn pairs), and insecticide measurements in maternal personal air during pregnancy as well as in umbilical cord plasma at delivery. Controlling for potential confounders, we found no association between maternal personal air insecticide levels and birth weight, length, or head circumference. For each log unit increase in cord plasma chlorpyrifos levels, birth weight decreased by 42.6 g [95% confidence interval (CI), -81.8 to -3.8, p = 0.03] and birth length decreased by 0.24 cm (95% CI, -0.47 to -0.01, p = 0.04). Combined measures of (ln)cord plasma chlorpyrifos and diazinon (adjusted for relative potency) were also inversely associated with birth weight and length (p < 0.05). Birth weight averaged 186.3 g less (95% CI, -375.2 to -45.5) among newborns with the highest compared with lowest 26% of exposure levels (p = 0.01). Further, the associations between birth weight and length and cord plasma chlorpyrifos and diazinon were highly significant (p < or = 0.007) among newborns born before the 2000-2001 U.S. Environmental Protection Agency's regulatory actions to phase out residential use of these insecticides. Among newborns born after January 2001, exposure levels were substantially lower, and no association with fetal growth was apparent (p > 0.8). The propoxur metabolite 2-isopropoxyphenol in cord plasma was inversely associated with birth length, a finding of borderline significance (p = 0.05) after controlling for chlorpyrifos and diazinon. Results indicate that prenatal chlorpyrifos exposures have impaired fetal growth among this minority cohort and that diazinon exposures may have contributed to the effects. Findings support recent regulatory action to phase out residential uses of the insecticides.

Evaluation of the effects of water disinfection by-products, bromochloroacetic and dibromoacetic acids, on frog embryogenesis

Adverse developmental effects of two haloacetic acids, bromochloroacetic acid (BCA) and dibromoacetic acid (DBA), were determined by using the Frog Embryo Teratogenesis Assay--Xenopus (FETAX). Xenopus embryos (150-400/concentration group) were exposed to 0, 8000, 10,000, 12,000, or 14,000 ppm BCA or 0, 10,000, 12,000, 14,000, or 16,000 ppm DBA for 96 h beginning from stage 8 (mid-blastula) to stage 46 (when primary organogenesis is complete). BCA produced 29, 83, and 100% mortality at 10,000, 12,000 and 14,000 ppm, respectively. Incidence of malformations among surviving embryos at 96 h for 10,000 and 12,000 ppm BCA were 8.4 and 68%. Thus LC50 and EC50 for BCA were between 10,000 and 12,000 ppm. DBA did not produce any significant mortality or malformation at any of the concentrations tested. In summary, BCA affected development of Xenopus embryos only at high concentrations, while DBA did not affect Xenopus development at the concentrations tested.

Evaluation of physiologically based models of pregnancy and lactation for their application in children's health risk assessments

In today's scientific and regulatory climates, an increased emphasis is placed on the potential health impacts for children exposed either in utero or by nursing to drugs of abuse, pharmaceuticals, and industrial or consumer chemicals. As a result, there is a renewed interest in the development and application of biologically based computational models that can be used to predict the dosimetry (or ultimately response) in a developing embryo, fetus, or newborn. However, fundamental differences between animal and human development can create many unique challenges. For example, unlike models designed for adults,biologically based models of pre-and postnatal development must deal with rapidly changing growth dynamics (maternal embryonic, fetal, and neonatal), changes in the state of differentiation of developing tissues, uniquely expressed or uniquely functioning signal transduction or enzymatic pathways, and unusual routes of exposure (e.g., maternal-mediated placental transfer and lactation). In cases where these challenges are overcome or addressed, biological modeling will likely prove useful in assessments geared toward children's health, given the contributions that this approach has already made in cancer and non-cancer human health risk assessments. Therefore, the purpose of this review is to critically evaluate the current state of the art in physiologically based pharmacokinetic (PBPK) and pharmacodynamic (PD) modeling of the developing embryo, fetus, or neonate and to recommend potential steps that could be taken to improve their use in children's health risk assessments. The intent was not to recommend improvements to individual models per se, but to identify areas of research that could move the entire field forward. This analysis includes a brief summary of current risk assessment practices for developmental toxicity, with an overview of developmental biology as it relates to species-specific dosimetry. This summary should provide a general context for understanding the tension that exists in modeling between describing biological proceses in exquisite detail vs. the simplifications that are necessary due to lack of data (or through a sensitivity analysis, determined to be of little impact) to develop individual PBPK or PD models. For each of the previously published models covered in this review, a description of the underlying assumptions and model structures as well as the data and methods used in model development and validation are highlighted. Although several of the models attempted to describe target tissues in the developing embryo, fetus, or neonate of laboratory animals, extrapolations to humans were largely limited to maternal blood or milk concentrations. Future areas of research therefore are recommended to extend the already significant progress that has been made in this field and perhaps address many of the technical policy, and ethical issues surrounding various approaches for decreasing the uncertainty in extrapolating from animal models to human pregnancies or neonatal exposures.

Evaluation of dimethoate-induced implantation delay and nidation by progesterone in albino mice

We investigated the effect of dimethoate, an organophosphorus insecticide, and progesterone on implantation. Virgin pregnant albino mice received dimethoate orally at a dose of 28 mg/kg body wt/d from days 1 to 7. Laparotomy on day 8 showed no implantation sites. Thereafter, graded doses of progesterone, 4, 9, and 12 mg/kg body wt/d, were administered up to day 15. A group of control mice received a similar quantity of distilled water. Autopsy on day 8 revealed that the control mice were pregnant, with a normal number of implantations and 8.08% pre-implantation loss, whereas treatment with dimethoate for 7 days or with dimethoate for 7 days followed by progesterone for 8 days totally abolished implantation, with a 100% pre-implantation loss. In all treated mice, a significant decrease occurred in body weight gain, as well as in the weight of the ovaries, uterus, and liver when compared with those of control mice. No significant changes were found in other organ weights (kidneys, adrenals, spleen, thymus, or thyroid). The observed effect of dimethoate could be due to an imbalance in the estrogen-progesterone ratio essential for implantation. Alternatively, dimethoate treatment could result in blastotoxicity or have an impact on the hypothalamic-pituitary axis.

Improved cleavage of bovine ICSI ova cultured in heparin-containing medium

Although heparin plays an important role in bovine sperm capacitation, there is no direct evidence for a role in embryonic development. The present study was designed to examine the effect of heparin on early development of bovine zygotes obtained by intracytoplasmic sperm injection (ICSI). Spermatozoa were treated with or without heparin, and the ICSI ova were cultured in a chemically defined medium + BSA, with or without heparin. Treatment of spermatozoa with heparin before ICSI or heparin in post-ICSI culture medium for 18 or 24h had a beneficial effect on pronuclear formation, cleavage rate (63% versus 76-83%), and number of cells in blastocysts (68 cells versus 82-109 cells; P < 0.05).

Prenatal nicotine exposure increases connective tissue expression in foetal monkey pulmonary vessels

Among the many deleterious effects of maternal smoking during pregnancy on foetal development, is a higher incidence of persistent pulmonary hypertension. The recent identification of nicotinic acetylcholine receptors (nAChR) on cells of the pulmonary vessel walls suggests that maternal smoking during pregnancy may produce morphological alterations in foetal pulmonary vasculature. Timed-pregnant rhesus monkeys were treated with nicotine (1 mg x kg(-1) x day(-1)) delivered by subcutaneous osmotic mini-pumps from days 26-134 of gestation (term: 165 days). Lung sections from 134-day foetal monkeys were used for morphometric analysis, in situ hybridisation and immunohistochemical staining. Following nicotine treatment, total wall and tunica adventitia thickness of airway associated vessels (AAV) increased significantly. Nicotine exposure significantly increased collagen I and III mRNA and protein in tunica adventitia in all AAV but not in tunica media. By contrast, levels of elastin protein were significantly decreased. alpha7 nAChR were detected in AAV fibroblasts that expressed collagen mRNA. Choline acetyltransferase, the enzyme which synthesises acetylcholine, the ligand for alpha7 nAChR was also detected in endothelium and fibroblasts. These findings suggest that with smoking during pregnancy, nicotine is transported across the placenta and directly interacts with nicotinic acetylcholine receptors in pulmonary vessels to alter connective tissue expression and therefore produce vascular structural alterations.

Effects of androstenedione on in utero development in rats

This study was conducted to characterize the effect of androstenedione on estrous cyclicity, mating behavior and fetal development. Thirty-day old rats received corn oil alone or androstenedione (in corn oil) at one of four concentrations (0, 1.0, 5.0, 10.0 or 30.0 mg/kg body weight) by gavage for two weeks prior to mating, during the mating period and throughout gestation. Dose related increases in serum androstenedione, estradiol and estrone were observed in all androstenedione treated animals at gestation day 20. A statistically significant increase in serum testosterone concentration was observed in the 30 mg/kg dose group. Feed and fluid consumption were not affected by androstenedione treatment during the pre-mating or gestational periods, however a statistically significant decrease in the number of females with regular estrous cycles was observed in the 10.0 and 30.0 mg/kg dose groups. Exposure to androstenedione did not affect mean body weight gain during pre-mating or gestation. Slight not statistically significant reductions in the number of implants, number of viable fetuses and number of viable male fetuses were observed in the 30.0 mg/kg androstenedione group. Reductions were not observed in the number of corpora lutea. Fetal growth in terms of fetal weight, crown-rump length, anogenital distance and the number of external abnormalities was not affected by androstenedione exposure. At the doses given, androstenedione had no specific effect on the development of individual bones, including sternebrae. Dose related effects of androstenedione were not observed on the development of soft tissues. A statistically significant increase in moderately enlarged ureter at the kidney was observed in both the 1.0 and 5.0 mg/kg dose groups. Organ weights (expressed per gram of body weight or per gram of brain weight) were not affected by androstenedione treatment.

Embryotoxicity and teratogenicity study with α-cyclodextrin in rats

The embryotoxicity/teratogenicity of alpha-cyclodextrin (alpha-CD) was examined in Wistar Crl:(WI)WU BR rats. alpha-CD was fed at dietary concentrations of 0, 1.5, 5, 10, or 20% to groups of 25 pregnant female rats from day 0 to 21 of gestation. An additional group received a diet with 20% lactose. The additions to the diet of alpha-CD and lactose were made at the expense of pregelatinized potato starch. Body weight as well as food and water intake were recorded during the treatment period. The rats were killed on day 21 and examined for standard parameters of maternal reproductive performance. The fetuses were examined for external abnormalities, body weight and crown rump length. Fetuses were examined for skeletal and visceral abnormalities. Generally, alpha-CD was well tolerated and no deaths occurred in any group. Weight gain and food consumption were similar in all groups during gestation, except for a slightly yet significantly increased food intake in the 20% alpha-CD group from day 6 to 21. Water intake was similar in all alpha-CD groups; in the lactose group, it was significantly higher than in the controls. Maternal reproductive performance was not affected by the alpha-CD treatment. Examination of the fetuses for external, visceral and skeletal changes did not reveal any fetotoxic, embryotoxic, or teratogenic effects of alpha-CD. In conclusion, no adverse effects were observed at alpha-CD intakes of up to 20% of the diet, the highest dose level tested at which the rats consumed about 13 g/kg bw/day.

Embryotoxicity and teratogenicity study with α-cyclodextrin in rabbits

In a standard embryotoxicity/teratogenicity study, alpha-cyclodextrin (alpha-CD) was administered to groups of sixteen, artificially inseminated New Zealand White rabbits at dietary concentrations of 0, 5, 10, or 20%. An additional group received a diet containing 20% lactose. Treatment started on day 0 of gestation and ended on day 29 when the animals were killed. Except for the occurrence of transient diarrhoea in one rabbit of the 20% alpha-CD group for a few days, the treatment was well tolerated. A reduced food intake in the 20% alpha-CD group during the first week of treatment resulted in a reduced weight gain from day 0 to 12 of the study. However, the difference to the controls was not significant and at termination of the study body weights were similar in all groups. Even at the highest dose level, which corresponds to an intake of 5.9-7.5 g/kg bw/day, no signs of maternal toxicity were observed. Maternal reproductive performance was not affected by the treatment. Uterine weight, placental weight, fetal weight, number of fetuses, sex ratio, number of implanation sites, resorptions, and corpora lutea did not differ among the groups. Visceral and skeletal examinations of the fetuses did not reveal any malformations, anomalies or variations that could be attributed to treatment. It was concluded that dietary alpha-CD is generally well tolerated by pregnant rabbits, has no adverse effect on maternal reproductive performance and is not embryotoxic, fetotoxic, or teratogenic at dietary concentrations of up to 20%, the highest dose level tested.

An in-vitro study of ginsenoside Rb1-induced teratogenicity using a whole rat embryo culture model

BACKGROUND

Ginseng is a commonly used herbal medicine worldwide. However, there is limited information regarding its effects on the developing embryo.

METHODS

The effect of ginsenoside on the developing embryo during the critical period of organogenesis was investigated using a whole rat embryo culture model. Embryos were exposed to various concentrations of ginsenoside Rb(1) and scored for growth and differentiation at the end of the culture period.

RESULTS

Median total morphological scores in embryos exposed to 30 micro g/ml of ginsenoside Rb(1) was significantly lower (P < 0.05) than that in control embryos (35 versus 45). Morphological scores for flexion, forelimb and hindlimb were also significantly reduced. The median total morphological scores further decreased to 28 when the concentration of ginsenoside Rb(1) was increased to 50 micro g/ml. At this concentration, the embryonic crown-rump length and somite number were also significantly reduced compared with control embryos (2.8 versus 3.0 mm and 16.0 versus 21.0, respectively).

CONCLUSIONS

Our study has demonstrated that ginsenoside exerts direct teratogenic effects on rat embryos. Until more is known about the effects of ginsenoside in women of reproductive age, we suggest its use should be treated with caution.

NMDA Receptors in the Developing Brain and Effects of Noxious Insults

This review covers normal expression of the NMDA receptor in the fetus and newborn, and then the response of the NMDA receptors within the central nervous system (CNS) during early development, to noxious stimuli. In the research setting, hypoxia is a commonly studied noxious stimulus that has been studied in a variety of contexts, including isolated hypoxia, or hypoxia combined with ischemia or hypercapnia, and delivered in single or repeated doses (intermittent stimuli). We review differences and commonalities between these experimental paradigms, and the sequelae of a common outcome, which is cell death, possibly through excitotoxic mechanisms. Finally, based on current literature, we will examine potential directions for clinical therapeutic interventions. By highlighting knowledge gaps in this field, we hope to encourage future research focusing on clinically relevant problems and outcomes in this area.

Use of inhaled steroids by pregnant asthmatic women does not reduce intrauterine growth

BACKGROUND

Inhaled steroids are recommended for the treatment of persistent asthma during pregnancy, but their potential effects on intrauterine growth have been inadequately evaluated.

OBJECTIVE

The purpose of this study was to evaluate the association between maternal use of specific inhaled steroids and inhaled steroid dose during pregnancy and the incidence of infants who are small for gestational age (SGA) and mean birth weight.

METHODS

Pregnant asthmatic women being treated with inhaled steroids were enrolled in the study before delivery by their managing allergists. Information regarding the specific inhaled steroid and daily dose used, requirement for oral steroids, occurrence of acute asthmatic episodes, maternal race, birth weight, gestational age, and congenital malformations was obtained for each patient. SGA was defined through use of a published normative sample of American births.

RESULTS

A total of 474 women were enrolled in the study; of the 451 enrolled participants whose pregnancy ended in a singleton live birth, 396 (88%) completed the study. The incidence of infants with low birth weight, preterm births, and congenital malformations in this cohort was not greater than expected in the general population. The incidence of SGA was 7.1% (95% CI, 5.0% to 10.1%). No significant relationships between specific inhaled steroid or dose of inhaled steroid used and either SGA or mean birth weight were observed.

CONCLUSION

These data suggest that the use of inhaled steroids by pregnant asthmatic women does not reduce intrauterine growth and supports the recommendation that inhaled steroids should be used in the management of persistent asthma during pregnancy.

Effects of Interleukin-12 Administration during the Pre- and Peri-Implantation Period on Mouse Embryofetal Development

PROBLEM

The immunological success of pregnancy is thought to depend upon the establishment of a balance between favorable and deleterious cytokines, the current paradigm viewing pregnancy as a T helper (Th)2 cytokine-dependent phenomenon. In this context, a particular attention should be directed to the potential role of interleukin (IL)-12, which promotes the development of Th1 responses, in the induction of adverse pregnancy-related phenomena. Indeed, very few data linked the Th1-inducer IL-12 to the event of abortion.

METHODS

In this study, we have investigated the maternal and fetal effects of exogenous administration of IL-12 to CD1 (BR) ICR mice during the pre- and peri-implantation period (day 2-6 of pregnancy). Animals have been evaluated for parameters of reproductive performance, embryo and fetal developmental toxicity and maternal toxicity.

RESULTS

Intraperitoneal administration of IL-12 at concentrations from 2.5 to 10 microg/kg daily did not result in an increase in the murine abortion rate. A statistically significant, although minimal, decrease in the number of somites were found in the embryos of animals treated with IL-12 at a dose of 10 microg/kg/day. However, developmental parameters at birth were similar between the two groups of animals suggesting that alteration of somites might be a transitory state during treatment. An increased body weight gains and reduced feed and water consumption were observed in the mothers treated with the cytokine.

CONCLUSION

In the present experimental conditions and in this specific strain of mice, IL-12 does not exert adverse effects on reproductive performance and induces an only modest harmful action on mothers and embryos.

Efects of the pine needle abortifacient, isocupressic acid, on bovine oocyte maturation and preimplantation embryo development

Isocupressic acid (ICA) [15-hydroxylabda-8 (17), 13E-dien-19-oic acid], a labdane diterpene acid, isolated from ponderosa pine (Pinus ponderosa), Lodgepole pine (Pinus contorta), common juniper (Juniperus communis) and Monterey cypress (Cupressus macrocarpa), induces abortion in pregnant cows when ingested primarily during the last trimester. The objective of this study was to investigate the effects of isocupressic acid on bovine oocyte maturation (in vitro maturation (IVM)-Experiment I) and preimplantation embryo development (in vitro culture (IVC)-Experiment II) using in vitro embryo production techniques and to subsequently evaluate viability and developmental competence of ICA-cultured embryos via embryo transfer to recipient heifers (Experiment III). A complete randomized block experimental design was used. In Experiment I and II, isocupressic acid was added to IVM or IVC media at 0 (TRT1, control), 1.3 (TRT2), and 2.6 microg/ml (TRT3) Results from Experiment I and II indicated that ICA did not inhibit oocyte maturation and did not adversely affect preinpiantation embryo development. Furthermore, results from Experiment II demonstrated that isocupressic acid enhanced bovine preimplantation embryo development in vitro in a dose dependent manner. Subsequently, Day 8 (Day 0 = IVF) blastocysts cultured in vitro in the medium containing 2.6 microg/ml ICA were transferred to recipient heifers and resulted in normal pregnancies as determined by ultrasound imaging. Subsequently, all but two births were normal as evaluated by post natal veterinary examination. In conclusion, ICA showed no adverse effects on oocyte maturation and preimplantation embryo development in vitro or subsequent viability in vivo using the ICA concentrations and in vitro culture parameters of this study.

Aryl hydrocarbon receptors in urogenital sinus mesenchyme mediate the inhibition of prostatic epithelial bud formation by 2,3,7,8-tetrachlorodibenzo-p-dioxin

In utero exposure of male C57BL/6 mice to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) prevents prostatic epithelial buds from forming in the ventral region of the urogenital sinus (UGS) and reduces the number of buds that form in the dorsolateral region. This inhibition of budding is aryl hydrocarbon receptor (AHR) dependent and appears to be the primary cause of lobe-specific prostate abnormalities in TCDD-exposed mice. TCDD can inhibit prostatic epithelial bud formation by acting directly on the UGS in vitro, but whether it does so via AHR in UGS mesenchyme, epithelium, or both was unknown. To address this issue, UGS mesenchyme and epithelium from gestation day (GD) 15 wild-type C57BL/6J male mice were isolated, recombined, and cultured in vitro for 5 days with 10(-8) M 5alpha-dihydrotestosterone (DHT) and either 10(-9) M TCDD or vehicle. Prostatic epithelial buds were viewed by light microscopy after removal of mesenchyme. Effects depended greatly on which portions of the mesenchyme were used: TCDD had little if any effect when whole UGS epithelium (UGE) was recombined with ventral plus dorsolateral mesenchyme, tended to reduce bud numbers in recombinants made with UGE and dorsolateral mesenchyme, and severely reduced bud numbers in recombinants made with UGE and ventral mesenchyme (VM). [VM + UGE] recombinants prepared from wild-type and AHR knockout (Ahr(-/-)) mice were then cultured with DHT to determine the site of action of TCDD. AHR null mutation alone had no effect on budding. TCDD severely inhibited prostatic epithelial bud formation in recombinants that contained mesenchymal AHR, whereas bud formation was not inhibited by TCDD in recombinants lacking mesenchymal AHR, regardless of epithelial AHR status. These results demonstrate that UGS mesenchyme and not UGS epithelium is the site of action of TCDD. Therefore, the initial events responsible for abnormal UGS (and ultimately prostate) development occur within the UGS mesenchyme, and changes in gene expression in the UGS epithelium responsible for inhibited prostatic budding are secondary to the direct effects of TCDD on UGS mesenchyme.

Impairment of male reproduction in adult rats exposed to hydroxyprogesterone caproate in utero

Hydroxyprogesterone caproate is one of the most effective and widely used drugs for the treatment of uterine bleeding and threatened miscarriage in women. Hydroxyprogesterone caproate was administered to pregnant rats in order to assess the effect of intraperitoneal exposure to supranormal levels of hydroxyprogesterone caproate on the male reproductive potential in the first generation. The cauda epididymal sperm count and motility decreased significantly in rats exposed to hydroxyprogesterone caproate during embryonic development, when compared with control rats. The levels of serum testosterone decreased with an increase in follicle stimulating hormone and luteinizing hormone in adult rats exposed to hydroxyprogesterone caproate during the embryonic stage. It was suggested that the impairment of male reproductive performance could be mediated through the inhibition of testosterone production.

Low-dose agrochemicals and lawn-care pesticides induce developmental toxicity in murine preimplantation embryos

Occupational exposures to pesticides may increase parental risk of infertility and adverse pregnancy outcomes such as spontaneous abortion, preterm delivery, and congenital anomalies. Less is known about residential use of pesticides and the risks they pose to reproduction and development. In the present study we evaluate environmentally relevant, low-dose exposures to agrochemicals and lawn-care pesticides for their direct effects on mouse preimplantation embryo development, a period corresponding to the first 5-7 days after human conception. Agents tested were those commonly used in the upper midwestern United States, including six herbicides [atrazine, dicamba, metolachlor, 2,4-dichlorophenoxyacetic acid (2,4-D)], pendimethalin, and mecoprop), three insecticides (chlorpyrifos, terbufos, and permethrin), two fungicides (chlorothalonil and mancozeb), a desiccant (diquat), and a fertilizer (ammonium nitrate). Groups of 20-25 embryos were incubated 96 hr in vitro with either individual chemicals or mixtures of chemicals simulating exposures encountered by handling pesticides, inhaling drift, or ingesting contaminated groundwater. Incubating embryos with individual pesticides increased the percentage of apoptosis (cell death) for 11 of 13 chemicals (p <or= 0.05) and reduced development to blastocyst and mean cell number per embryo for 3 of 13 agents (p <or= 0.05). Mixtures simulating preemergent herbicides, postemergent herbicides, and fungicides increased the percentage of apoptosis in exposed embryos (p <or= 0.05). Mixtures simulating groundwater contaminants, insecticide formulation, and lawn-care herbicides reduced development to blastocyst and mean cell number per embryo (p <or= 0.05). Our data demonstrate that pesticide-induced injury can occur very early in development, with a variety of agents, and at concentrations assumed to be without adverse health consequences for humans.

Effect of glutamine on preimplantation mouse embryo development in vitro

OBJECTIVES

The purpose of this research was to study the independent effect of the amino acid glutamine on preimplantation mouse embryo development in vitro.

STUDY DESIGN

Two-cell stage mouse embryos were cultured in human tubal fluid medium in the presence and absence of 1 mmol/L of glutamine. Outcomes for morphology and cleavage rates were compared with Fisher's and Mann-Whitney's tests, respectively.

RESULTS

Glutamine increased the proportion of embryos that developed to the blastocyst stage (86.4%) compared with those cultured without glutamine (59.1%) (P =.052). The percentages of embryos developing to the morula or hatching blastocyst stages were comparable in the 2 groups. Blastocyst total cell numbers were significantly higher in the glutamine group (34+/-1.7 vs 18.5+/-3.5, respectively; values are mean+/-SEM, P =.044).

CONCLUSION

The amino acid glutamine independently improves preimplantation mouse embryo development in vitro. Further studies are needed to examine the applicability of these results to humans.