Prenatal Toxicity Study Research Articles

Toxic effects of 70% ethanol extract of Moringa stenopetala leaf (Baker f.) Cufod. (Moringaceae) on fetus and placenta of pregnant Wistar rats

BackgroundMoringa stenopetala leaves (Baker f.) Cufod. (Moringaceae) are used as a staple food and traditional medicine for treating various diseases like malaria, hypertension, stomach pain, diabetes, elevated cholesterol, and removing the retained placenta. Its prenatal toxicity study is minimal. Thus, this study aimed to assess the toxic effects of a 70% ethanol extract of Moringa stenopetala leaf on the fetuses and placentas of pregnant Wistar rats.MethodFresh leaves of Moringa stenopetala were collected, dried at room temperature, ground to powder, and extracted using 70% ethanol. For this study, five groups of animals, each containing ten pregnant rats, were used. Groups I–III were experimental groups and treated with 250, 500, and 1000 mg/kg body weight of Moringa stenopetala leaf extract, respectively. Groups IV and V were pair-fed and ad libitum control groups. The extract was given during gestation days 6 to 12. The fetuses were recovered at day 20 of gestation and examined for the presence of developmental delays, gross external malformations, skeletal and visceral defects. Gross and histopathological changes in the placenta were also evaluated.ResultsCompared to the pair-fed control group, maternal daily food intake and weight gain were reduced in the 1000 mg/kg-treated group during the treatment and post-treatment periods. A significantly higher number of fetal resorptions was also seen in the 1000 mg/kg treatment group. The crown-rump length and fetal and placental weights were all significantly reduced in pregnant rats given 1000 mg/kg. However, there were no visible malformations in the visceral organs as well as external genitalia in all the treatment and control groups. About 40.7% of the fetuses in the 1000 mg/kg treated rats had no proximal hindlimb phalanges. In addition, light microscopic investigations of the placenta in the high-dose treated rats revealed structural changes in the decidual basalis, trophoblastic zone, and labyrinthine zones.ConclusionIn conclusion, consumption of M. stenopetala leaves at a higher dose may have toxic effects on the development of rat fetuses. At a higher dose, the plant extract increased the number of fetal resorptions, reduced the number of fetuses, decreased the fetal and placental weights, and alter the placental histopathology. Thus, it is recommended to limit the excess feeding of M. stenopetala leaves during gestation.

Influence of pregnancy and non-fasting conditions on the plasma metabolome in a rat prenatal toxicity study.

The current parameters for determining maternal toxicity (e.g. clinical signs, food consumption, body weight development) lack specificity and may underestimate the extent of effects of test compounds on the dams. Previous reports have highlighted the use of plasma metabolomics for an improved and mechanism-based identification of maternal toxicity. To establish metabolite profiles of healthy pregnancies and evaluate the influence of food consumption as a confounding factor, metabolite profiling of rat plasma was performed by gas- and liquid-chromatography-tandem mass spectrometry techniques. Metabolite changes in response to pregnancy, food consumption prior to blood sampling (non-fasting) as well as the interaction of both conditions were studied. In dams, both conditions, non-fasting and pregnancy, had a marked influence on the plasma metabolome and resulted in distinct individual patterns of changed metabolites. Non-fasting was characterized by increased plasma concentrations of amino acids and diet related compounds and lower levels of ketone bodies. The metabolic profile of pregnant rats was characterized by lower amino acids and glucose levels and higher concentrations of plasma fatty acids, triglycerides and hormones, capturing the normal biochemical changes undergone during pregnancy. The establishment of metabolic profiles of pregnant non-fasted rats serves as a baseline to create metabolic fingerprints for prenatal and maternal toxicity studies.

Added value of plasma metabolomics to describe maternal effects in rat maternal and prenatal toxicity studies

For regulatory purposes prenatal developmental toxicity (OECD No. 414) studies are routinely performed in our laboratories. The suitability of metabolomics as technology to identify maternal toxicity in such studies was investigated. Plasma was sampled from pregnant, non-fasted rats on gestation day 20 before cesarean section. Metabolite profiling was performed by gas- and liquid-chromatography-tandem mass spectrometry techniques. The sensitivity of routinely examined maternal toxicity parameters (OECD No. 414) was compared to those of metabolome analysis. Evaluating 44 studies, the metabolome-derived NOEL was more sensitive in 45% of the cases in detecting maternal toxicity than the maternal NOAEL. Metabolome patterns indicative for liver effects and 4-hydroxyphenylpyruvate dioxygenase (HPPD) enzyme-inhibition were established in pregnant rats based on regulated metabolites using reference compounds. The HPPD inhibition and liver toxicity patterns in pregnant rats were reasonably comparable to the ones established in non-pregnant, fasted rats. Metabolomics is a useful tool for an improved and mechanism-based identification of maternal toxicity in maternal and prenatal toxicity studies. The data suggest that the current classical maternal toxicity parameters may underestimate the extent of effects of compounds on the dams.

Developmental toxicity of N-methylaniline following prenatal oral administration in rats.

The objective of the study was to assess prenatal toxicity of N-methylaniline (NMA) administered by gavage to pregnant female rats. Pregnant female rats were administered N-methylaniline in corn oil by gavage at daily doses of 0.8 mg/kg of body weight (b.w.), 4 mg/kg b.w., 20 mg/kg b.w. and 100 mg/kg b.w. from implantation (the 5th day post mating) to the day prior to the scheduled caesarean section (the 20th day of pregnancy). General behavior, body weight, food and water consumption, hematological, biochemical analyses and pathomorphological changes of the dams were recorded. All the females survived until the end of the study. The test substance was toxic to pregnant females, even at the lowest of the used doses, i.e., 0.8 mg/kg b.w./day. Lower weight gain during pregnancy and significantly higher NMA-dose-dependent absolute weight of the organs were noted in the exposed females. The females from the groups exposed at doses of 20 mg/kg b.w./day and 100 mg/kg b.w./day developed anemia and showed higher concentrations of free thyroxine (FT3) and free triiodothyronine (FT4) thyroid hormones. Total protein concentration exhibited an increase in all the exposed groups of females. In the prenatal toxicity study, administration of N-methylaniline throughout the embryonic and fetal periods produced embryotoxic effects at doses ranging 4-100 mg/kg b.w./day. Considering the data obtained in this study, it is reasonable to assume that N-methylaniline administered orally to pregnant rats is toxic for mothers even at a low dose of 0.8 mg/kg b.w./day. However, this dose was not associated with any significant effects to their offspring. This prenatal exposure level may be considered as no-observed-adverse-effect level (NOAEL) for the progeny and a dose of 4 mg/kg b.w./day as the lowest-observed-adverse-effect level (LOAEL) for the progeny.

Conference Program: 43rd Annual Conference of the European Teratology

Synthetic amorphous silica is a nanostructured material, which is produced and used in a wide variety of technological applications and consumer products. No regulatory prenatal toxicity studies with this substance were reported yet. Therefore, synthetic amorphous silica was tested for prenatal toxicity, according to OECD guideline 414 in Wistar rats following oral (gavage) administration at the dose levels 0, 100, 300, or 1000 mg/kg bw/d from gestation day 6–19. At gestation day 20, all pregnant animals were examined by cesarean section. Numbers of corpora lutea, implantations, resorptions, live and dead fetuses were counted. Fetal and placental weights were determined. Fetuses were examined for external, visceral and skeletal abnormalities. No maternal toxicity was observed at any dose level. Likewise, administration of the test compound did not alter cesarean section parameters and did not influence fetal or placental weights. No compound-related increase in the incidence of malformations or variations was observed in the fetuses. The no observed adverse effect level (NOAEL) was 1000 mg/kg bw/d.

Prenatal toxicity of synthetic amorphous silica nanomaterial in rats

Synthetic amorphous silica is a nanostructured material, which is produced and used in a wide variety of technological applications and consumer products. No regulatory prenatal toxicity studies with this substance were reported yet. Therefore, synthetic amorphous silica was tested for prenatal toxicity, according to OECD guideline 414 in Wistar rats following oral (gavage) administration at the dose levels 0, 100, 300, or 1000mg/kg bw/d from gestation day 6-19. At gestation day 20, all pregnant animals were examined by cesarean section. Numbers of corpora lutea, implantations, resorptions, live and dead fetuses were counted. Fetal and placental weights were determined. Fetuses were examined for external, visceral and skeletal abnormalities. No maternal toxicity was observed at any dose level. Likewise, administration of the test compound did not alter cesarean section parameters and did not influence fetal or placental weights. No compound-related increase in the incidence of malformations or variations was observed in the fetuses. The no observed adverse effect level (NOAEL) was 1000mg/kg bw/d.

Relative parameter sensitivity in prenatal toxicity studies with substances classified as developmental toxicants

Developmental toxicity testing according to the globally standardized OECD 414 protocol is an important basis for decisions on classification and labeling of developmental toxicants in the European Union (EU). This test requires relatively large animal numbers, given that parental and offspring generations are involved. In vitro assay designs and systems biology paradigms are being developed to reduce animal use and to improve prediction of human hazard. Such approaches could benefit from the long-term experience with animal protocols and more specifically from information on the relevance of effects observed in these tests for developmental toxicity. Therefore, we have analyzed relative parameter sensitivity in 22 publicly available developmental toxicity studies, representing about one third of all classified developmental toxicants under European legislation. Maternal and fetal weight effects and fetal survival were most often affected parameters at the developmental Lowest Observed Adverse Effect Level (dLOAEL), followed by skeletal malformations. Specific end points such as cleft palate were observed in fewer studies at dLOAEL, but if observed may have been crucial in classification and labeling decisions. These results are similar to earlier studies using different selections of chemicals, indicating that in general classified developmental toxicants have a similar pattern of effects at the dLOAEL as chemicals in general. These findings are discussed within the perspective of the development of innovative alternative approaches to developmental hazard assessment.

Final Report on the Safety Assessment of HC Red No. 71

HC Red No. 7 functions as a semipermanent (direct) hair colorant in one cosmetic product at 1%. Analytical studies found the relative purity of HC Red No. 7 to be > 98.5%. Impurities may include 2-nitro-benzene-1,4-diamine; 3-(4-amino-3-nitro-phenyl)-oxazolin-2-one; 2-chloroethyl 4-amino-3-nitrophenylcarbamate; residual solvents ethanol, DMF, or isopropyl acetate; chloride ions; and heavy metals. Around 0.10% of the applied HC Red No. 7 was absorbed in human dermatomed skin samples. In an acute oral toxicity study in rats, the maximum nonlethal dose was 300 mg/kg. The no observed effect level (NOEL) in a subchronic oral toxicity study in rats was 50 mg/kg day(- 1). HC Red No. 7 was not a dermal or ocular irritant in rabbits, but lymphoproliferative responses in mice indicated that HC Red No. 7 should be considered a moderate sensitizer. The NOEL for maternal toxicity was 50 mg/kg/day and the no observed adverse effect level (NOAEL) for embryonic development was 200 mg/kg/day in a prenatal toxicity study of HC Red No. 7 using rats. HC Red No. 7 was nonmutagenic at the hprt locus but mutagenic at the TK locus in mouse lymphoma cells, was mutagenic in several Salmonella typhimurium strains, was not active in an unscheduled DNA synthesis assay, and was unclear in a micronucleus assay in human lymphocyte cultures. No carcinogenicity studies were available, nor were any clinical tests reported. Available hair dye epidemiology studies are insufficient to conclude a causal relationship between hair dye use and cancer or other diseases, but more relevant is that direct hair dyes, although not the focus in all investigations, appear to have little evidence of an association with adverse events as reported in epidemiology studies. As reviewed by the Cosmetic Ingredient Review (CIR) Expert Panel, HC Red No. 7 appears to be a moderate sensitizer in animals. No human sensitivity data concerning this ingredient have been reported. However, hair dyes containing HC Red No. 7, as coal tar hair dye products, are exempt from the principal adulteration provision and from the color additive provisions in sections 601 and 706 of the Federal Food, Drug, and Cosmetic Act, when the label bears a caution statement and patch test instructions for determining whether the product causes contact dermatitis. The Expert Panel expects that following this procedure will identify prospective individuals who would have an irritation/sensitization reaction and allow them to avoid significant exposures. The CIR Expert Panel also noted that mutagenicity studies available for HC Red No. 7 gave both positive and negative results. Based on the available data, it was concluded that, at most, this ingredient is a weak mutagen. Due to its low dermal absorption potential and its use as a semipermanent hair dye, the CIR Expert Panel believes there is low risk of genotoxicity and that HC Red No. 7 is safe as a hair dye ingredient in the practices of use and concentrations as described in this safety assessment.

Prenatal toxicity studies in rats and rabbits with the calcium channel blocker diproteverine

In prenatal toxicity studies, diproteverine, a calcium channel blocker with demonstrated antianginal properties, produced an unusual pattern of digital, heart, tail, and vertebral defects in rat fetuses from mothers treated during the major period of organogenesis, but only a very low incidence of heart abnormalities was seen in the rabbit. Heart changes were rarely seen in association with digital defects. The findings were consistent with those seen with other calcium channel blockers and add weight to the suggestion of Danielsson and colleagues (5) that digital malformations are a class effect for this type of compound, the effects being related to reduced uteroplacental blood flow. In addition, it is proposed that cardiovascular malformations are also a class response with calcium channel blockers. The distribution of fetal death and hemorrhages and the varying association between cardiovascular, digital, and tail abnormalities seen in the rat with increasing doses of diproteverine fits the pattern of changes reported following hypoxia in the chick embryo. Reduced uteroplacental blood flow with resultant embryonic hypoxia secondary to pharmacologic action is considered a probable mechanism of action for the induction of abnormalities produced by calcium channel blockers.

Significance of the Minor Alterations of the Axial Skeleton in Rat Foetuses. A Short Review

Abstract The toxicological significance of different kinds of minor alterations in the axial skeleton of foetal rat is still a matter of debate. These changes can be better evaluated by means of the double staining technique for cartilage and calcified tissue, which helps to distinguish between deficient calcification and actual structural changes. Sternebral alterations are a frequent finding in prenatal toxicity studies, while in humans they are seldom observed. However, very few data exist for the rat with regard to their persistence and/or consequences in postnatal life. Abnormalities of the vertebral bodies might be functionally important, but comparatively little attention has been given to them in prenatal toxicology. By contrast, the little significance of wavy ribs, potentially reversible alterations, has been extensively studied. The transiency of extra ribs in the rat might be a species‐specific feature, but they have been reported to cause health problems in humans. It is important to recognize a dose‐dependent trend both for specific minor changes and for general parameters (e.g., sternebral alterations). Finally, the range of prevalences in historical controls may be an insensitive parameter, due to the wide variability between different control groups. This range could be better replaced by the average prevalence ± Standard Deviation.

Studies on the prenatal toxicity of N, N-dimethylformamide in mice, rats and rabbits

Prenatal toxicity studies with N, N-dimethylformamide (DMF) in rabbits, rats and mice were carried out using the oral (gavage), dermal, inhalation and ip injection routes of administration. Administration of DMF by gavage led to an increase in malformations in rats and mice in the absence of overt maternal toxicity. The lowest-observable-effect level was 182 mg/kg body weight/day in mice and 166 mg/kg body weight/day in rats. After dermal administration a dose-dependent incidence of teratogenicity was observed in rats at 94–944 mg/kg/body weight/day in the absence of overt maternal toxicity. In rabbits dermal administration led to a steeper increase in the dose-response relationship and at 400 mg/kg body weight/day to a clear teratogenic effect in the presence of slight maternal toxicity. The 200 mg/kg body weight/day dose appeared to be the no-adverse-effect level. Inhalation in rats caused foetotoxicity and embryolethality at 287 ppm. A clear teratogenic effect was shown in rabbits at 450 ppm and a marginal effect at 150 ppm. The no-effect level for does and foetuses was 50 ppm. Ip injection in mice caused clear teratogenicity at 944 mg/kg body weight/day and slight embryotoxicity at 378 mg/kg body weight/day. The rabbit appears to be more sensitive than the rat to DMF-related prenatal toxicity and should, therefore, be used as the basis for the evaluation of teratogenic risk in humans.

A study of the prenatal and postnatal toxicity of a sulfhydryl resin in rats

This study evaluates the effects of a sulfhydryl resin on embryonal, fetal and neonatal development in rats. Doses of 150 or 1500 mg/kg/day were administered on days 3 through 15 of gestation in a prenatal toxicity study and on day 16 of gestation through day 14 of lactation in a perinatal toxicity study. In the prenatal study, fetuses were delivered by cesarean section on day 21 of gestation and were examined grossly, measured and weighed. Following routine preparations, the soft tissues and skeletons were examined. Evidence of retarded fetal development (delayed ossification of skull bones and sternebrae) was observed at the high dose level. Teratogenic effects were not observed at either dose level. Perinatal administration of the sulfhydryl resin had no effect on parturition or neonatal growth and survival. A finding at necropsy of the 3-week-old neonates of resin-treated dams, dilated urinary bladder, was not associated with any functional problems or microscopic morphologic abnormality of urinary tract structures. In both the prenatal and perinatal studies, 150 mg of sulfhydryl resin/kg/day had no effect on the developing embryo, fetus or neonate.