Pyriproxyfen does not cause microcephaly or malformations in a preclinical mammalian model

Supplementation of high doses of vitamin D during the gestational period do not cause reproductive, teratogenic and genotoxic damage in mice

Vitamin D deficiency during pregnancy may have adverse effects on embryo-fetal and postnatal development. Indeed, vitamin D supplementation has been indicated for pregnant women. However, there are no studies that indicate the safe dose of this supplementation during the gestational period. Therefore, the present study assessed the effects of high doses of vitamin D and vitamin D combined with calcium on reproductive performance, embryo-fetal development, and DNA integrity in Swiss mice. A total of 140 pregnant female mice treated with vitamin D and vitamin D combined with calcium were analyzed in two experiments. In one experiment, mice received intramuscular supplementation at doses of 600,000, 6,000,000, or 60,000,000 IU of vitamin D. These same doses were also associated with the dose of 8.56 mg/kg of calcium. In the other experiment, mice received a single oral dose of 6,000, 60,000, or 600,000 IU of vitamin D. These same doses were also associated with the dose of 8.56 mg/kg of calcium. The treatments were always carried out in the 10th gestational day. The results show that neither intramuscularly nor orally administered vitamin D and vitamin D combined with calcium affected reproductive performance, embryo-fetal development, or DNA integrity at the different doses tested. These pioneering results confirm the safety of using this type of high doses of supplementation, including during pregnancy.

Assessment of toxicity of pyriproxyfen, Bacillus thuringiensis, and malathion and their mixtures used for mosquito control on embryo-larval development and behavior of zebrafish

Pyriproxyfen (PPF), Bacillus thuringiensis israelensis (BTI), and malathion (MLT) are widely used worldwide to control the population of mosquitos that transmit arboviruses. The current work aimed to evaluate the toxicity of these single pesticides and their binary mixtures of PPF + BTI, PPF + MLT, and MLT + BTI on the embryo-larval stage of zebrafish (Danio rerio) as an animal model. Epiboly, mortality, apical endpoints, affected animals, heart rate, morphometric, thigmotaxis, touch sensitivity, and optomotor response tests were evaluated. PPF and MLT and all mixtures reduced the epiboly percentage. Mortality increased significantly in all exposed groups, except BTI, with MLT being the most toxic. The observed apical endpoints were pericardial and yolk sac edemas, and tail and spine deformation. Exposure to MLT showed a higher percentage of affected animals. A reduction in heart rate was also observed in MLT- and PPF + MLT-exposed groups. The PPF + MLT mixture decreased head measurements. Behavioral alterations were observed, with a decrease in thigmotaxis and touch sensitivity responses in PPF + MLT and MLT + BTI groups. Finally, optomotor responses were affected in all groups. The above data obtained suggest that the MLT + PFF mixture has the greatest toxicity effects. This mixture affected embryo-larval development and behavior and is close to the reality in several cities that use both pesticides for mosquito control rather than single pesticides, leading to a reevaluation of the strategy for mosquito control.

The Ethanolic Extract of Piper glabratum Kunth Is Teratogenic and Interferes with the Ossification Process of Swiss Mice Fetuses

Piper glabratum Kunth is a plant traditionally used to treat pain and inflammation in the Mato Grosso do Sul, Brazil. Even pregnant women consume this plant. Toxicology studies of the ethanolic extract from the leaves of P. glabratum (EEPg) could establish the safety of popular use of P. glabratrum. Thus, the effects of the ethanolic extract of leaves of P. glabratum (EEPg) on the reproductive performance and embryofetal development of Swiss mice were evaluated. Pregnant female mice were treated with 100, 1000 and 2000 mg/kg throughout the gestational period by gavage (p.o). The control group received the EEPg vehicle (Tween 80–1%) in the proportion of 0.1 mL/10 g (p.o.). The results demonstrated that EEPg has low maternal toxic potential and does not alter the reproductive performance of females. However, it altered embryofetal development and caused fetal weight reduction (increasing the frequency of small-for-gestational-age fetuses) at the two highest doses. In addition, it interfered with placental weight, placental index and placental efficiency. The frequency of visceral malformations increased by 2.8 times for the lowest dose of EEPg, and skeletal malformations increased by 2.48, 1.89 and 2.11 times for doses of 100, 1000 and 2000 mg/kg of EEPg, respectively. It is noteworthy that 100% of the offspring treated with EEPg showed changes in the ossification process. Thus, it is considered that the EEPg has low maternal toxic potential; it does not alter the reproductive performance of females. However, it is teratogenic and interferes, mainly, in the ossification process, and therefore its use is contraindicated in the gestational period.

The Ethanolic Extract of Gomphrena celosioides Mart. Does Not Alter Reproductive Performance or Embryo-Fetal Development, nor Does It Cause Chromosomal Damage

Gomphrena celosioides is a native Brazilian plant found in the State of Mato Grosso do Sul. It is used in folk medicine to treat kidney diseases, skin diseases, infections, rheumatism, gastrointestinal diseases, and respiratory diseases. It is also used as an abortifacient. To evaluate the effects of the ethanolic extract of Gomphrena celosioides (EEGc) on reproductive performance, embryo development, and chromosome stability, Swiss mice were randomly divided into experimental groups (n = 10). The animals in the control group received the vehicle Tween 80-1% in the proportion of 0.1 mL/10 g of body weight orally, from the first to the 18th gestational day. The animals in the treatment groups received the EEGc (100, 1000, and 2000 mg/kg) from the first to the 18th gestational day. The animals underwent evaluations of their reproductive performance and embryofetal development. The results showed that the EEGc did not change the animals' final weight, weight gain, uterine weight, or net weight gain. The evaluation showed that the absolute and relative organs' weights did not vary between the different experimental groups. In addition, the EEGc did not change the numbers of implants, live fetuses, dead fetuses, or fetal resorptions. There were no differences in post-operative loss rates, implantations, or resorptions, nor were there differences in fetal viability or sex ratio. The use of the EEGc did not result in different frequencies of malformations. In addition, the EEGc did not alter the frequency of chromosomal damage or frequency of micronuclei. Based on our findings, we considered the extract of Gomphrena celosioides to be safe for use during pregnancy, although some parameters indicated caution in its use.

The pyriproxyfen metabolite, 4'-OH-PPF, disrupts thyroid hormone signaling in neural stem cells, modifying neurodevelopmental genes affected by ZIKA virus infection

North-Eastern Brazil saw intensive application of the insecticide pyriproxyfen (PPF) during the microcephaly outbreak caused by the Zika virus (ZIKV). ZIKV requires the neural RNA-binding protein Musashi-1 to replicate. Thyroid hormone (TH) represses MSI1. PPF is a suspected TH disruptor. We hypothesized that co-exposure to the main metabolite of PPF, 4'-OH-PPF, could exacerbate ZIKV effects through increased MSI1 expression. Exposing an in vivo reporter model, Xenopus laevis, to 4'-OH-PPF decreased TH signaling and increased msi1 mRNA and protein, confirming TH-antagonistic properties. Next, we investigated the metabolite's effects on mouse subventricular zone-derived neural stem cells (NSCs). Exposure to 4'-OH-PPF dose-dependently reduced neuroprogenitor proliferation and dysregulated genes implicated in neurogliogenesis. The highest dose induced Msi1 mRNA and protein, increasing cell apoptosis and the ratio of neurons to glial cells. Given these effects of the metabolite alone, we considered if combined infection with ZIKV worsened neurogenic events. Only at the fourth and last day of incubation did co-exposure of 4'-OH-PPF and ZIKV decrease viral replication, but viral RNA copies stayed within the same order of magnitude. Intracellular RNA content of NSCs was decreased in the combined presence of 4'-OH-PPF and ZIKV, suggesting a synergistic block of transcriptional machinery. Seven out of 12 tested key genes in TH signaling and neuroglial commitment were dysregulated by co-exposure, of which four were unaltered when exposed to 4'-OH-PPF alone. We conclude that 4'-OH-PPF is an active TH-antagonist, altering NSC processes known to underlie correct cortical development. A combination of the TH-disrupting metabolite and ZIKV could aggravate the microcephaly phenotype.