Teratogenic effects of noise and cadmium in mice: does noise have teratogenic potential?

Effect of Predator Stress on the Reproductive Performance of Female Mice After Nonsurgical Embryo Transfer

Predator Stress Can Exert Detrimental Effects on Female Mammals, Leading to Disrupted Reproduction. Although Many Studies Have Addressed the Effects of Predator Stress on Reproductive Output in Rodents, Few Studies Have Focused on the Effect of Visual or Auditory Stress on Pregnant Females. in This Study, We Investigated the Possible Effect of Predator Stress, Either Visual Only or Combined Visual and Auditory (visual+auditory), on the Reproductive Performance of Female Mice After Nonsurgical Embryo Transfer. Reproductive Performance Was Assessed As Pregnancy Rate, Implantation Rate, Gestation Length, Live Pup Rate, and Neonatal Birth Weight. Moreover, Serum Cortisol and Progesterone Levels in Dams Were Measured by Using Electrochemiluminescence Immunoassay. Exposure to Predator (cat) Stress Did Not Lead to a Significant Change in Pregnancy Rates in the Tested Mice. However, the Stressed Mice Showed Significantly Decreased Implantation Rates Compared with the Control Group. Similarly, the Live Pup Rate and Neonatal Birth Weight Were Significantly Lower in the Group Exposed to Preda- Tor Stress Than in the Control Group. Furthermore, Mice Exposed to Visual+auditory Stress Showed a Significant Reduction in Gestation Length Compared with the Control Mice. Our Data Showed That Predator Visual+auditory Stress As Combined Stimuli Significantly Increased Serum Cortisol Level. in Contrast, Progesterone Levels Did Not Significantly Vary Among the Experimental Groups. Taken Together, Our Findings Imply That Predator Stress Adversely Affects the Reproductive Efficiency of Pregnant Mice By Decreasing the Implantation Rate, Live Birth Rate, and Neonatal Birth Weight and by Prolonging Gestation Length.

Reproductive outcomes associated with noise exposure - a systematic review of the literature

Introduction: High noise exposure during critical periods in gestation is a potential stressor that may result in increased risk of implantation failure, dysregulation of placentation or decrease of uterine blood flow. This paper systematically reviews published evidence on associations between reproductive outcomes and occupational and environmental noise exposure. Methods: The Web of Science, PubMed and Embase electronic databases were searched for papers published between 1970 to June 2014 and via colleagues. We included 14 epidemiological studies related to occupational noise exposure and nine epidemiological studies related to environmental noise exposure. There was some evidence for associations between occupational noise exposure and low birthweight, preterm birth and small for gestational age, either independently or together with other occupational risk factors. Five of six epidemiologic studies, including the two largest studies, found significant associations between lower birthweight and higher noise exposure. There were few studies on other outcomes and study design issues may have led to bias in assessments in some studies. Conclusions: There is evidence for associations between noise exposure and adverse reproductive outcomes from animal studies. Few studies in have been conducted in humans but there is some suggestive evidence of adverse associations with environmental noise from both occupational and epidemiological studies, especially for low birthweight.

Safe sound exposure in the fetus and preterm infant

Exposure to sound can have beneficial and harmful effects on the developing fetus and preterm infant. Although recommendations for safe exposure to sound have existed for more than three decades, reports indicate that these recommendations are not being followed. Recommendations are made to promote attention to the problem of unsafe exposure to sound in early development, and a multidisciplinary team, including representatives from disciplines beyond medicine and nursing, must redress safe exposure.

In vitro evaluation of magnetic resonance imaging at 3.0 tesla on clonogenic ability, proliferation, and cell cycle in human embryonic lung fibroblasts

OBJECTIVES

We investigated the influence of magnetic resonance (MR) at 3.0 T on clonogenic ability, proliferation, and cell cycle in an embryonic human cell line.

MATERIALS AND METHODS

Cells (human lung fibroblasts Hel 299) were exposed to the static magnetic field (3.0 T) of a magnetic resonance imager (MRI) and to a turbo spin echo sequence at 3.0 T within clinical limitations (specific absorption rate 0.92 W/kg). A special MR-compatible incubation system was used. A control group (sham-exposed) and a MRI group (exposed) were set up. We investigated 3 biologic endpoints: colony forming, cell cycle, and proliferation ability. The exposure time was 2 hours in each experiment.

RESULTS

In the statistical analysis, none of these tests showed relevant differences between the exposed and sham-exposed group.

CONCLUSIONS

No influences of the static field alone as well as a turbo spin echo sequence at 3.0 T on clonogenic ability, proliferation, or cell cycle in eugenic human lung fibroblasts were found.

Study of the hearing in children born from pregnant women exposed to occupational noise: Assessment by distortion product otoacoustic emissions

AIM

To detect early on a probable hearing loss in children of women exposed to occupational noise during their pregnancy and to verify if there is any difference between the children from those women exposed to occupational noise during their pregnancy and the ones from mothers that do not work under the same conditions.

METHODS

Children from women exposed to occupational noise during their pregnancy and children from women who were not exposed were evaluated through distortion product otoacoustic emissions, using the GSI 60 DPOEA SYSTEM equipment and the frequency-ratio F2/F1 equal to 1.2 and the geometric average of 2F1-F2. The intensity of the primary frequencies were kept steady with values of L1=65dBSPL and L2=55dBSPL for F1 and F2, respectively. Student T test in paired samples and independent samples were used.

RESULTS

There were no differences in the response amplitude of distortion product otoacoustic emissions between the control and the study groups. There was no statistically difference between male and female children in response amplitude for the two groups aforementioned; and there were no differences between right and left ears from each group.

CONCLUSION

We did not observe hearing impairment in children whose mothers were exposed to occupational noise during pregnancy when compared to the children from mothers who were not. There was no difference between the right and left ears, nor between male and female children in each group.

Enhancement of developmental toxicity effects of chemicals by gestational stress. A review

Risk assessment of developmental toxicants is almost exclusively based on single chemicals studied in animals under controlled experimental conditions, as to reduce stress. Although humans may be exposed simultaneously to numerous hazards, little is known about the interaction of prenatal chemical exposures with other factors, such as maternal stress, itself a modifier of fetal development. Gestational stress has been hypothesized to enhance the developmental toxicity of chemicals. This review identified 36 animal studies investigating if maternal stress may enhance the effects of prenatal chemical exposure, and evaluated the presented hypothesis. Studies of a broad range of chemicals and developmental endpoints support the notion, that maternal stress is able to enhance the effects of developmental toxicants, although stress mitigated chemically induced effects in a few cases. Maternal stress most often enhanced chemical developmental toxicity at dose levels associated with severe maternal toxicity or where test agents were already above threshold for effect. Thus, LOAEL(chemical) was generally similar to LOAEL(chemical+stress), although not necessarily for the same endpoint. It should be noted that the database contained a limited number of studies, and only a single high dose level was applied in most studies, rendering establishment of NOAELs for combined exposures impossible. Furthermore, for some compounds, the margin between human exposure levels and the LOAEL(chemical+stress) seems small. Future studies are recommended to investigate compounds, for which maternal stress was already proven as an enhancer, at lower dose levels. Interactive response seems to depend on stressor severity and timing of chemical exposure relative to maternal stress which should be further scrutinized.

Early Developmental Exposure to BDE 99 or Aroclor 1254 Affects Neurobehavioural Profile: Interference from the Administration Route

Among the most persistent and bio-accumulative environmental pollutants are the polybrominated diphenyl ethers (PBDEs), a class of chemicals widely used as flame retardants in plastics and textile coating, and the polychlorinated biphenyls (PCBs), previously used as coolants and lubricants in electrical equipment. Monitoring programs revealed high levels of both these classes of compounds in human breast milk, raising concerns for their potential noxious effects on infants. The aim of the present study was to investigate the neurotoxic effects of 2,2',4,4',5-penta BDE (BDE 99: 18mg/kg/day) or Aroclor 1254 (A1254, a PCB mixture: 10mg/kg/day) administration, from gestational day (GD) 6 to postnatal day (PND) 21, on neurobehavioral development in the CD-1 Swiss mouse. In addition, we investigated whether the administration route affects the emergence or the magnitude of the toxic effects of BDE 99 or A1254. In particular, we compared self-administration, consisting in letting the mouse drink spontaneously the compound dissolved in oil from a syringe, with gavage, consisting in force-feeding a substance by a tube inserted in the mouth and then into the stomach, a procedure reported to be stress-inducing. Both compounds induced hyperactivity, though BDE 99 affected activity profile only during adolescence and A1254 mainly at adulthood. Levels of total circulating thyroxine were decreased by both BDE 99 and A1254 administration, though only in the latter group the decrease was statistically significant. These findings suggest a different neurotoxic action exerted by PBDEs and PCBs. An effect of the administration route, independent from the compound administered, was found on thigmotactic behavior and gavage administration affected pup body weight gain only in the A1254 group, suggesting that the stress induced by gavage procedure may either affect results per se or modulate the detrimental action of selected compounds.

Effects of prenatal exposure to chronic mild stress and toluene in rats

The aim of the present study was to elucidate whether prenatal chronic stress, in combination with exposure to a developmental neurotoxicant, would increase effects in the offspring compared with the effects of either exposure alone. Development and neurobehavioral effects were investigated in female offspring of pregnant rats (Mol:WIST) exposed to chronic mild stress (CMS) during gestational days (GD) 9-20, or 1500 ppm toluene, 6 h/day during gestational days 7-20, or a combination of the two. Prenatal CMS was associated with decreased thymic weight and increased auditory startle response. The corticosterone response to restraint seemed modified by prenatal exposure to toluene. Lactational body weight was decreased in offsprings subjected to CMS, primarily due to effects in the combined exposure group. Cognitive function was investigated in the Morris water maze, and some indications of improved function due to CMS were observed. In the present experimental setting, there was no indication of the two exposures potentiating each other with respect to adverse effects on the nervous system. However, the effects of prenatal CMS indicate that stress during fetal life may interfere with the development of the thymus and increase the reactivity (startle reflex) of the offspring.

Interactions in developmental toxicology: combined action of restraint stress, caffeine, and aspirin in pregnant mice

BACKGROUND

Stress can result in an increased use of substances such as caffeine and aspirin. The effect of maternal stress on concurrent exposure to caffeine and aspirin on prenatal development was assessed in mice.

METHODS

On gestational day 9, mice were assigned to three treatment groups orally exposed to caffeine (30 mg/kg), aspirin (250 mg/kg), or a combination of caffeine (30 mg/kg) and aspirin (250 mg/kg). Three additional groups of pregnant animals received similar caffeine and aspirin doses and were immediately subjected to restraint for 14 hr. Control groups included unrestrained and restrained pregnant mice not exposed to caffeine or aspirin. All dams were euthanized on gestational day 18. Live fetuses were evaluated for sex, body weight, and external, internal, and skeletal malformations and variations.

RESULTS

A single oral dose of caffeine or aspirin did not cause significant maternal toxicity. However, coadministration of these drugs with restraint produced some adverse maternal effects (i.e., reduction in maternal weight gain and food consumption on gestational days 9-11). In relation to embryo/fetal toxicity, the incidence of some skeletal defects was significantly increased after exposure to caffeine, aspirin, or maternal restraint, and their binary and ternary combinations.

CONCLUSIONS

Although caffeine and aspirin were given in a single dose in this study, the results suggest that prenatal stress could slightly exacerbate the maternal and developmental toxicity of the combination of these drugs in mice.

In vitro evaluation of teratogenic effects by time-varying MR gradient fields on fetal human fibroblasts

The purpose of this study was to evaluate the influence on fetal cell growth in vitro of rapidly changing magnetic gradient fields such as those produced by the gradient coils of a typical magnetic resonance (MR) imager. The static magnetic field and the radiofrequency pulses were disabled during all measurements. Human fetal fibroblasts were placed within a specially designed MR-compatible incubation system inside the magnet. Trapezoid-shaped waveforms of 500 and 75 Hz base frequency and an amplitude of 2 mT were applied for 2-24 hours. Proliferation of the cells was monitored for 3 weeks after exposure. Cell cycle analysis was performed until 24 hours after exposure to detect alterations in cell division. Tests were performed under two different conditions of growth to detect increased as well as decreased proliferation effects. None of these tests showed differences in proliferation and cell cycle distribution between exposed and nonexposed cells.

The effect of maternal restraint on developmental toxicity of aluminum in mice

Both aluminum (Al) and maternal restraint have been reported to cause developmental toxicity in mammals. This study assessed in pregnant mice the potential interaction between Al and maternal restraint. Four groups of plug-positive female mice were given IP injections of AlCl3 at 37.5 and 75 mg/kg/day on days 6-15 of gestation. Two of these groups were also subjected to restraint for 2 h/day during the same gestational days. Control groups included restrained and unrestrained pregnant mice nonexposed to Al. Cesarean sections were performed on gestation day 18, and the fetuses were weighed and examined for morphological defects. Maternal toxicity was significantly enhanced by restraint at 75 mg AlCl3/kg/day. No increases in the number of resorptions or dead fetuses per litter were observed following exposure to Al, maternal restraint, or combined Al and restraint. However, a significant decrease in fetal body weight, as well as a significant increase in the number of litters with morphologic defects, was observed in the group exposed to 75 mg AlCl3/kg/day plus maternal restraint. The current results suggest that maternal restraint could enhance the metal-induced developmental toxicity (reduced fetal body weight, increase in the number of litters with morphologic defects) only at high doses of the metal, which are also toxic to the dam.

The coelomic cavity--a reservoir for metals

OBJECTIVE

The concentrations of metals in fluids surrounding the first-trimester fetus were measured.

STUDY DESIGN

Atomic absorption spectrometry was used to measure concentrations of metals in matched samples of amniotic and extraembryonic coelomic fluids in 17 women between 9 and 12 weeks of pregnancy.

RESULTS

Concentrations of calcium, magnesium, iron, copper, and manganese (but not zinc, cadmium, or lead) were significantly higher in coelomic than in amniotic fluid. There was no significant difference between levels of iron, manganese, and lead in controls and amniotic fluid or between concentrations of manganese, cadmium, and lead in controls and coelomic fluid. There was no relationship between the concentrations of each metal in amniotic and coelomic fluid.

CONCLUSION

The extraembryonic coelom is an important site of concentration of metals in early pregnancy. This might represent a store of metals essential for normal embryonic and fetal development or constitute a defense mechanism against environmental conditions adverse to the fetus.

Effects of maternal stress on methylmercury-induced developmental toxicity in mice

The developmental toxicity of combined exposure to maternal restraint stress and methylmercury chloride (MMC) was assessed in Swiss mice. On day 10 of gestation, four groups of plug-positive female mice were treated (p.o.) with a single dose of 12.5 or 25 mg MMC/kg. Immediately after MMC exposure, two of those groups were subjected to restraint for 14 hr. Control groups included restrained and unrestrained pregnant mice nonexposed to MMC. Combined exposure to 25 mg MMC/kg and restraint enhanced MMC-induced maternal toxicity, which included deaths and decreased body weight gain and food consumption. The number of nonviable implants was also increased significantly following concurrent exposure to MMC (25 mg/kg) and restraint, with the percentage of postimplantation loss increased from 64% (MMC alone) to 100% (MMC plus restraint). However, the types and incidence of internal and skeletal anomalies observed after administration of 12.5 mg MMC/kg were not increased by maternal restraint. These results suggest that maternal stress would enhance the MMC-induced maternal and embryo/fetal toxicity at doses of MMC that are highly toxic to the dams, whereas at doses that are less acutely toxic the role of maternal stress would not be significant.

Sister-chromatid exchanges after exposure to metal-containing emissions

The effect of in vivo feeding of metal-containing emissions from an aluminum refining plant upon the induction of sister-chromatid exchanges (SCEs) and mitotic delay was investigated in cultured sheep lymphocytes. The experimental animals were given a daily dose of industrial emissions (mostly aluminum and fluoride) of either 0.75 g or 1.5 g/animal, for 1 year. The experiments were aimed at induction of chronic fluorosis under clinical conditions. A significant increase in mean serum fluoride, aluminum, arsenic and cadmium levels between both experimental groups and control was observed from 5 and 7 months on, respectively. The occurrence of SCEs in the experimental groups was higher (reaching statistical significance at a dose of 1.5 g/animal) than that seen in the controls. The emission was found to reduce the proliferation index. A significant heterogeneity of the first, second and third metaphases as compared to the controls was also observed.