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

Meptyldinocap induces implantation failure by forcing cell cycle arrest, mitochondrial dysfunction, and endoplasmic reticulum stress in porcine trophectoderm and endometrial luminal epithelial cells

Meptyldinocap is a dinitrophenol fungicide used to control powdery mildew. Although other dinitrophenol pesticides have been found to exhibit reproductive toxicity, studies of meptyldinocaps are scarce. This study investigated the adverse effects of meptyldinocap on porcine trophectoderm (pTr) and porcine endometrial luminal epithelial (pLE) cells, which play crucial roles in implantation. We confirmed that meptyldinocap decreased cell viability, induced apoptosis, and inhibited proliferation by decreasing proliferation-related gene expression and inducing changes in the cell cycle. Furthermore, meptyldinocap treatment caused mitochondrial dysfunction, endoplasmic reticulum stress, and disruption of calcium homeostasis. Moreover, it induces alterations in mitogen-activated protein kinase signaling cascades and reduces the migration ability, leading to implantation failure. Our findings suggest that meptyldinocap reduces the cellular functions of pTr and pLE cells, which are important for the implantation process, and interferes with interactions between the two cell lines, potentially leading to implantation failure. We also propose a mechanism by which the understudied fungicide meptyldinocap exerts its cytotoxicity.

Enhancing developmental and reproductive toxicity knowledge: A new AOP stemming from glutathione depletion

Integrated approaches to testing and assessments (IATAs) have been proposed as a method to organise new approach methodologies in order to replace traditional animal testing for chemical safety assessments. To capture the mechanistic aspects of toxicity assessments, IATAs can be framed around the adverse outcome pathway (AOP) concept. To utilise AOPs fully in this context, a sufficient number of pathways need to be present to develop fit for purpose IATAs. In silico approaches can support IATA through the provision of predictive models and also through data integration to derive conclusions using a weight-of-evidence approach. To examine the maturity of a developmental and reproductive toxicity (DART) AOP network derived from the literature, an assessment of its coverage was performed against a novel toxicity dataset. A dataset of diverse compounds, with data from studies performed according to OECD test guidelines TG-421 and TG-422, was curated to test the performance of an in silico model based on the AOP network - allowing for the identification of knowledge gaps within the network. One such gap in the knowledge was filled through the development of an AOP stemming from the molecular initiating event 'glutathione reaction with an electrophile' leading to male fertility toxicity. The creation of the AOP provided the mechanistic rationale for the curation of pre-existing structural alerts to relevant key events. Integrating this new knowledge and associated alerts into the DART AOP network will improve its coverage of DART-relevant chemical space. In addition, broadening the coverage of AOPs for a particular regulatory endpoint may facilitate the development of, and confidence in, robust IATAs.

Dwarfism and insulin resistance in male offspring caused by α1-adrenergic antagonism during pregnancy

OBJECTIVE

Maternal and environmental factors control the epigenetic fetal programming of the embryo, thereby defining the susceptibility for metabolic or endocrine disorders in the offspring. Pharmacological interventions required as a consequence of gestational problems, e.g. hypertension, can potentially interfere with correct fetal programming. As epigenetic alterations are usually only revealed later in life and not detected in studies focusing on early perinatal outcomes, little is known about the long-term epigenetic effects of gestational drug treatments. We sought to test the consequences of maternal α1-adrenergic antagonism during pregnancy, which can occur e.g. during hypertension treatment, for the endocrine and metabolic phenotype of the offspring.

METHODS

We treated C57BL/6NCrl female mice with the α1-adrenergic antagonist prazosin during pregnancy and analyzed the male and female offspring for endocrine and metabolic abnormalities.

RESULTS

Our data revealed that maternal α1-adrenergic blockade caused dwarfism, elevated body temperature, and insulin resistance in male offspring, accompanied by reduced IGF-1 serum concentrations as the result of reduced hepatic growth hormone receptor (Ghr) expression. We subsequently identified increased CpG DNA methylation at the transcriptional start site of the alternative Ghr promotor caused by the maternal treatment, which showed a strong inverse correlation to hepatic Ghr expression.

CONCLUSIONS

Our results demonstrate that maternal α1-adrenergic blockade can constitute an epigenetic cause for dwarfism and insulin resistance. The findings are of immediate clinical relevance as combined α/β-adrenergic blockers are first-line treatment of maternal hypertension.

Oral Toxicity of 2,4-Dinitroanisole in Rats

Subacute and subchronic studies were conducted to assess the toxicity of 2,4-dinitroanisole (DNAN) and to provide information important for protecting the health of military and civilian personnel. In the subchronic study, male and female Sprague-Dawley rats were dosed with DNAN via oral gavage at 0, 1.25, 5, 20, and 80 mg/kg/d. Likely owing to its conversion to 2,4-dinitrophenol, an inhibitor of energy homeostasis, DNAN caused an apparent increase in metabolism, leading to reduced feed efficiency ratios and body mass gains in males. Anemia, splenic enlargement, hemosiderosis, and extramedullary hematopoiesis indicated blood as a target organ, with females more sensitive than males. The DNAN was a testicular toxicant, causing decreased mass of testes and epididymides, as well as degeneration and atrophy of testicular seminiferous tubules and epididymal aspermia. Stereotypical behavior in males, gait irregularities, and cerebellar lesions indicated that DNAN is neurotoxic. Splenic enlargement, anemia, testicular toxicity, and neurotoxicity occurred only at or near lethal doses in the subchronic study.

Variation in the link between oxygen consumption and ATP production, and its relevance for animal performance

It is often assumed that an animal's metabolic rate can be estimated through measuring the whole-organism oxygen consumption rate. However, oxygen consumption alone is unlikely to be a sufficient marker of energy metabolism in many situations. This is due to the inherent variability in the link between oxidation and phosphorylation; that is, the amount of adenosine triphosphate (ATP) generated per molecule of oxygen consumed by mitochondria (P/O ratio). In this article, we describe how the P/O ratio can vary within and among individuals, and in response to a number of environmental parameters, including diet and temperature. As the P/O ratio affects the efficiency of cellular energy production, its variability may have significant consequences for animal performance, such as growth rate and reproductive output. We explore the adaptive significance of such variability and hypothesize that while a reduction in the P/O ratio is energetically costly, it may be associated with advantages in terms of somatic maintenance through reduced production of reactive oxygen species. Finally, we discuss how considering variation in mitochondrial efficiency, together with whole-organism oxygen consumption, can permit a better understanding of the relationship between energy metabolism and life history for studies in evolutionary ecology.

2,4-dinitrophenol (DNP): a weight loss agent with significant acute toxicity and risk of death

2,4-Dinitrophenol (DNP) is reported to cause rapid loss of weight, but unfortunately is associated with an unacceptably high rate of significant adverse effects. DNP is sold mostly over the internet under a number of different names as a weight loss/slimming aid. It causes uncoupling of oxidative phosphorylation; the classic symptom complex associated with toxicity of phenol-based products such as DNP is a combination of hyperthermia, tachycardia, diaphoresis and tachypnoea, eventually leading to death. Fatalities related to exposure to DNP have been reported since the turn of the twentieth century. To date, there have been 62 published deaths in the medical literature attributed to DNP. In this review, we will describe the pattern and pathophysiology of DNP toxicity and summarise the previous fatalities associated with exposure to DNP.

Expression profile of rat hippocampal neurons treated with the neuroprotective compound 2,4-dinitrophenol: up-regulation of cAMP signaling genes

2,4-Dinitrophenol (DNP) is classically known as a mitochondrial uncoupler and, at high concentrations, is toxic to a variety of cells. However, it has recently been shown that, at subtoxic concentrations, DNP protects neurons against a variety of insults and promotes neuronal differentiation and neuritogenesis. The molecular and cellular mechanisms underlying the beneficial neuroactive properties of DNP are still largely unknown. We have now used DNA microarray analysis to investigate changes in gene expression in rat hippocampal neurons in culture treated with low micromolar concentrations of DNP. Under conditions that did not affect neuronal viability, high-energy phosphate levels or mitochondrial oxygen consumption, DNP induced up-regulation of 275 genes and down-regulation of 231 genes. Significantly, several up-regulated genes were linked to intracellular cAMP signaling, known to be involved in neurite outgrowth, synaptic plasticity, and neuronal survival. Differential expression of specific genes was validated by quantitative RT-PCR using independent samples. Results shed light on molecular mechanisms underlying neuroprotection by DNP and point to possible targets for development of novel therapeutics for neurodegenerative disorders.

Toxicity of the Yangtze River source of drinking water on reproductive system of male mice (Mus musculus)

The toxicological tests of the Yangtze River source of drinking water on the reproductive system of male mice (Mus musculus) were conducted in order to protect human and environmental health. The mice were fed with the source water for 90-day and their body weights and relative organ weights were not significantly altered. The results of flow cytometry analysis showed that the relative percentage of the primary spermatocytes (4C) increased significantly, however, significant depletion was observed in the relative percentage of elongated spermatid (HC). These alterations in different germ cell populations were reflected in the various germ cell ratios. The ratio of 1C:4C showed declines while the ratio of 4C:2C increased and the percentage of abnormal sperm increased significantly. There were obvious testicular histopathology distinguishes observed in expansion of interstitial space and reduction in the number and size of Leydig cells. The data demonstrated that the source of drinking water from Yangtze River had actual toxicity on male mice reproductive system and suggested that the source water pollution should be controlled for protection of human health.