Carbofuran alters centrosome and spindle organization, and delays cell division in oocytes and mitotic cells

How Do Environmental Toxicants Affect Oocyte Maturation Via Oxidative Stress?

In mammals, oogenesis initiates before birth and pauses at the dictyate stage of meiotic prophase I until luteinizing hormone (LH) surges to resume meiosis. Oocyte maturation refers to the resumption of meiosis that directs oocytes to advance from prophase I to metaphase II of meiosis. This process is carefully modulated to ensure a normal ovulation and successful fertilization. By generating excessive amounts of oxidative stress, environmental toxicants can disrupt the oocyte maturation. In this review, we categorized these environmental toxicants that induce mitochondrial dysfunction and abnormal spindle formation. Further, we discussed the underlying mechanisms that hinder oocyte maturation, including mitochondrial function, spindle formation, and DNA damage response.

Fertility loss: negative effects of environmental toxicants on oogenesis

There has been a global decline in fertility rates, with ovulatory disorders emerging as the leading cause, contributing to a global lifetime infertility prevalence of 17.5%. Formation of the primordial follicle pool during early and further development of oocytes after puberty is crucial in determining female fertility and reproductive quality. However, the increasing exposure to environmental toxins (through occupational exposure and ubiquitous chemicals) in daily life is a growing concern; these toxins have been identified as significant risk factors for oogenesis in women. In light of this concern, this review aims to enhance our understanding of female reproductive system diseases and their implications. Specifically, we summarized and categorized the environmental toxins that can affect oogenesis. Here, we provide an overview of oogenesis, highlighting specific stages that may be susceptible to the influence of environmental toxins. Furthermore, we discuss the genetic and molecular mechanisms by which various environmental toxins, including metals, cigarette smoke, and agricultural and industrial toxins, affect female oogenesis. Raising awareness about the potential risks associated with toxin exposure is crucial. However, further research is needed to fully comprehend the mechanisms underlying these effects, including the identification of biomarkers to assess exposure levels and predict reproductive outcomes. By providing a comprehensive overview, this review aims to contribute to a better understanding of the impact of environmental toxins on female oogenesis and guide future research in this field.

Carbofuran pesticide toxicity to the eye

Pesticide exposure to eyes is a major source of ocular morbidities in adults and children all over the world. Carbofuran (CF), N-methyl carbamate, pesticide is most widely used as an insecticide, nematicide, and acaricide in agriculture, forestry, and gardening. Contact or ingestion of carbofuran causes high morbidity and mortality in humans and pets. Pesticides are absorbed in the eye faster than other organs of the body and damage ocular tissues very quickly. Carbofuran exposure to eye causes blurred vision, pain, loss of coordination, anti-cholinesterase activities, weakness, sweating, nausea and vomiting, abdominal pain, endocrine, reproductive, and cytotoxic effects in humans depending on amount and duration of exposure. Pesticide exposure to eye injures cornea, conjunctiva, lens, retina, and optic nerve and leads to abnormal ocular movement and vision impairment. Additionally, anticholinesterase pesticides like carbofuran are known to cause salivation, lacrimation, urination, and defecation (SLUD). Carbofuran and its two major metabolites (3-hydroxycarbofuran and 3-ketocarbofuran) are reversible inhibitors of acetylcholinesterase (AChE) which regulates acetylcholine (ACh), a neurohumoral chemical that plays an important role in corneal wound healing. The corneal epithelium contains high levels of ACh whose accumulation by AChE inhibition after CF exposure overstimulates muscarinic ACh receptors (mAChRs) and nicotinic ACh receptors (nAChRs). Hyper stimulation of mAChRs in the eye causes miosis (excessive constriction of the pupil), dacryorrhea (excessive flow of tears), or chromodacryorrhea (red tears). Recent studies reported alteration of autophagy mechanism in human cornea in vitro and ex vivo post carbofuran exposure. This review describes carbofuran toxicity to the eye with special emphasis on corneal morbidities and blindness.

Brain DNA damage analysis in pesticide exposed wistar albino rats (Rattus norvegicus): a chemometric approach

Brain the most important organ which controls most of the regulations in the body is composed of neurons and glia. As brain has a high metabolic rate and reduced cell renewal capability, the lipids, proteins and nucleic acids become the major targets of damage. In the present study carbofuran (CF) induced brain DNA damage in male wistar albino rats at sub-lethal doses (Control-A; B-1.0, C-0.5 and D-0.3 mg/kg BW) while the groups B1,C1, D1, B2, C2, D2 and B3, C3, D3 represents the exposure duration 30, 60 and 90 days each respectively. FTIR spectroscopy based chemometric analysis of functional groups in nucleic acids are reported, changes in band area and band frequencies were examined to understand the DNA damage by constructing heat map. Significant changes were observed in the band frequency, band areas, bandwidth and intensity values (p < 0.05, 0.01, 0.001). The principal component analysis was analyzed to study the alterations at the molecular level, which revealed maximum variance of 74% in groups A, B1, C1, D1 and C2 and 13.7% variance in B2, D2, B3, C3 and D3. The present study provides significant details to analyse DNA damage using non-conventional approach and can also be used for detecting DNA damage in several neural diseases and disorders and emphasizes on using FTIR spectral data through chemometric approach to analyse the DNA damage.Communicated by Ramaswamy H. Sarma.

African Herbal Medicines: Adverse Effects and Cytotoxic Potentials with Different Therapeutic Applications

The African continent is naturally endowed with various plant species with nutritional and medicinal benefits. About 80% of the people in developing countries rely on folk medicines to treat different diseases because of indigenous knowledge, availability, and cost-effectiveness. Extensive research studies have been conducted on the medicinal uses of African plants, however, the therapeutic potentials of some of these plants has remained unexploited. Over the years, several studies have revealed that some of these African floras are promising candidates for the development of novel drugs. Despite the plethora of studies on medicinal plant research in Africa, there is still little scientific data supporting the folkloric claims of these plants. Besides, safety in the use of folk medicines has been a major public health concern over the year. Therefore, it has become mandatory that relevant authority should take measures in safeguarding the populace on the use of herbal mixtures. Thus, the present review extracted relevant information from different scientific databases and highlighted some problems associated with folk medicines, adverse effects on reproductive systems, issue about safety due to the toxicity of some plants and their toxicity effects with potential therapeutic benefits are discussed.

Insecticides and ovarian functions

Insecticides, a heterogeneous group of chemicals, are widely used in agriculture and household practices to avoid insect-inflicted damage. Extensive use of insecticides has contributed substantially to agricultural production and the prevention of deadly diseases by destroying their vectors. On the contrary, many of the insecticides are associated with several adverse health effects like neurological and psychological diseases, metabolic disorders, hormonal imbalance, and even cancer in non-target species, including humans. Reproduction, a very selective process that ensures the continuity of species, is affected to a greater extent by the rampant use of insecticides. In females, exposure to insecticides leads to reproductive incapacitation primarily through disturbances in ovarian physiology. Disturbed ovarian activities encompass the alterations in hormone synthesis, follicular maturation, ovulation process, and ovarian cycle, which eventually lead to decline in fertility, prolonged time-to-conceive, spontaneous abortion, stillbirths, and developmental defects. Insecticide-induced ovarian toxicity is effectuated by endocrine disruption and oxidative stress. Oxidative stress, which occurs due to suppression of antioxidant defense system, and upsurge of reactive oxygen and nitrogen species, potentiates DNA damage and expression of apoptotic and inflammatory markers. Insecticide exposure, in part, is responsible for ovarian malfunctioning through disruption of hypothalamic-pituitary-gonadal axis. The current article is focused on the adverse effects of insecticides on ovarian functioning, and consequently, on the reproductive efficacy of females. The possible strategies to combat insecticide-induced toxicity are also discussed in the latter part of this review. Environ. Mol. Mutagen. 61:369-392, 2020. © 2020 Wiley Periodicals, Inc.

In Vivo acrylamide exposure may cause severe toxicity to mouse oocytes through its metabolite glycidamide

High acrylamide (ACR) content in heat-processed carbohydrate-rich foods, as well as roasted products such as coffee, almonds etc., has been found to be as a risk factor for carcinogenicity and genotoxicity by The World Health Organization. Glycidamide (GLY), the epoxide metabolite of ACR, is processed by the cytochrome P-450 enzyme system and has also been found to be a genotoxic agent. The aim of this study was to determine whether ACR and/or GLY have any detrimental effect on the meiotic cell division of oocytes. For this purpose, germinal vesicle-stage mouse oocytes were treated with 0, 100, 500, or 1000 μM ACR or 0, 25, or 250 μM GLY in vitro. In vivo experiments were performed after an intraperitoneal injection of 25 mg/kg/day ACR of female BALB/c mice for 7 days. The majority of in vitro ACR-treated oocytes reached the metaphase-II stage following 18 hours of incubation, which was not significantly different from the control group. Maturation of the oocytes derived from in vivo ACR-treated mice was impaired significantly. Oocytes, reaching the M-II stage in the in vivo ACR-treated group, were characterized by a decrease in meiotic spindle mass and an increase in chromosomal disruption. In vitro GLY treatment resulted in the degeneration of all oocytes, indicating that ACR toxicity on female germ cells may occur through its metabolite, GLY. Thus, ACR exposure must be considered, together with its metabolite GLY, when female fertility is concerned.

Can dicoumarol be used as a gonad-safe anticancer agent: an in vitro and in vivo experimental study

STUDY HYPOTHESIS

Dicoumarol (DC) has potential for use as a gonad-safe anticancer agent.

STUDY FINDING

DC altered cell proliferation, decreased viability and increased apoptosis in Vero and MCF-7 cell lines but did not show any toxic effect on mouse ovarian tissues and developing oocytes in vitro and in vivo.

WHAT IS KNOWN ALREADY

DC suppresses cell proliferation and increases apoptosis in various cancer cells such as breast, urogenital and melanoma. DC has also been reported to alter the anticancer effects of several chemotherapeutics, including cisplatin, gemcitabine and doxorubicin in prostate, liver and uroepithelial cancer cells, respectively.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

Vero (African green monkey kidney epithelial cells) and MCF-7 (human cancerous breast epithelial cells) cell lines and mouse granulosa cells isolated from 21-day-old female BALB/c mice (n = 21) were used to assess the effects of DC (10, 50, 100 and 200 µm) for 24 and 48 h on cell proliferation, viability and apoptotic cell death. In vivo experiments were performed with a single i.p. injection of 32 mg/kg DC in 21-day-old female BALB/c mice (n = 12). Following 48 h, animals were sacrificed by cervical dislocation and histological sections of isolated ovaries were evaluated for apoptosis. Viability assays were based on the trypan blue dye exclusion method and an automated cell counter device was used. Terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling (TUNEL) and Annexin-V immunofluorescence were assessed by 3D confocal microscopy to address apoptotic cell death. We also assessed whether DC inhibits cell proliferation and viability through NQO1 [NAD(P)H Quinone Oxidoreductase 1], an intracellular inhibitor of reactive oxygen species (ROS). The meiotic spindle and chromosomes were studied in mouse oocytes by α-β-tubulin and 7-aminoactinomycine D (7-AAD) immunostaining in vitro and in vivo.

MAIN RESULTS AND THE ROLE OF CHANCE

DC does not block oocyte maturation and no significant alteration was noted in meiotic spindle or chromosome morphology in metaphase-II (M-II) stage oocytes following DC treatment in vitro or in vivo. In contrast, exposure to DC for 24 h suppressed cell proliferation (P = 0.026 at 200 µm), decreased viability (P = 0.002 at 200 µm) and increased apoptosis (P = 0.048 at 100 µm) in Vero and MCF-7 cell lines, compared with controls. These changes were not related to intracellular NQO1 levels. Mouse granulosa cells were unaffected by 50 or 100 µm DC treatment for 24 and 48 h in vitro. DC treatment in vivo did not alter the number of primordial follicles or the ratio of apoptosis in primordial, primary and secondary follicles, as well as in antral follicles, compared with the controls.

LIMITATIONS, REASONS FOR CAUTION

DC was tested for ovarian toxicity only in isolated mouse oocytes/ovaries and healthy BALB/c mice. No cancer formation was used as an in vivo test model. The possibility that DC may potentiate ovarian toxicity when combined with traditional chemotherapeutic agents, such as mitomycin-C, cisplatin, gemcitabine and doxorubicin, must be taken into account, as DC is known to alter their effects in some cancer cells.

WIDER IMPLICATIONS OF THE FINDINGS

The present study evaluated, for the first time, the effect of DC on ovarian tissue. The results suggested that DC is not toxic to ovarian tissues and developing oocytes; therefore, DC should be assessed further as a potential anticancer agent when female fertility preservation is a concern.

LARGE SCALE DATA

N/A.

STUDY FUNDING AND COMPETING INTERESTS

This work includes data from dissertation thesis entitled 'Effects of dicoumarol on mitotic and meiotic cells as an anticancer agent' by DA, 2014 and was partly supported by The National Scientific and Technological Research Council of Turkey (SBAG-109S415) to AC, OC and SO. The authors confirm that this article content presents no conflicts of interest.