Stereological study on the effect of vitamin C in preventing the adverse effects of bisphenol A on rat ovary

Ascorbic acid protects the toxic effects of aflatoxin B1 on yak oocyte maturation

High-quality oocytes are a prerequisite for successful fertilization. Mammals feeding on aflatoxin-contaminated feed can cause reproductive toxicity, including follicular atresia, poor oocyte development and maturation, and aberrant epigenetic modifications of oocytes. In addition, the important role of ascorbic acid (AA) in reproductive biology has been confirmed, and AA is widely used as an antioxidant in cell culture. However, the toxic effects of aflatoxin B₁ (AFB₁ ) on yak oocytes and whether AA has protective effects remain unknown. In this study, we found that exposure to AFB₁ impedes meiotic maturation of oocytes, promotes apoptosis by triggering high levels of reactive oxygen species (ROS), and disrupts mitochondrial distribution and actin integrity, resulting in a decrease in the fertilization ability and parthenogenetic development ability of oocytes. In addition, these injuries changed the DNA methylation transferase transcription level of mature oocytes. After adding 50 μg/ml AA, the indices recovered to levels close to those of the control group. The results showed that AA could protect yak oocytes from the toxic effects of AFB₁ and improve the quality of oocytes.

The Influence of Environmental Factors on Ovarian Function, Follicular Genesis, and Oocyte Quality

Endocrine-disrupting chemicals (EDCs) exist ubiquitously in the environment. Epidemiological data suggest that the increasing prevalence of infertility may be related to the numerous chemicals. Exposure to EDCs may have significant adverse impacts on the reproductive system including fertility, ovarian reserve, and sex steroid hormone levels. This chapter covers the common exposure ways, the origins of EDCs, and their effects on ovarian function, follicular genesis, and oocyte quality. Furthermore, we will review the origin and the physiology of ovarian development, as well as explore the mechanisms in which EDCs act on the ovary from human and animal data. And then, we will focus on the bisphenol A (BPA), which has been shown to reduce fertility and ovarian reserve, as well as disrupt steroidogenesis in animal and human models. Finally, we will discuss the future direction of prevention and solution methods.

Ascorbic acid ameliorates dysregulated folliculogenesis induced by mono-(2-ethylhexyl)phthalate in neonatal mouse ovaries via reducing ovarian oxidative stress

Phthalates, including di-(2-ethylhexyl)phthalate (DEHP), are common industrial chemicals in the environment. Recent evidence indicates that DEHP and its active metabolite mono-(2-ethylhexyl)phthalate (MEHP) negatively modulate reproductive functions and induce reactive oxygen species. Ascorbic acid (AA) is a dietary requirement for primates, and it acts as a potent free radical scavenger to protect tissues against oxidative stress. In this study, to investigate the toxic effects of MEHP on the follicle development and the beneficial role of AA, neonatal mouse ovaries were treated with different concentrations of MEHP with or without AA for 6 days. Then, the follicle constitution and oxidative status were compared in different groups. Results showed MEHP accelerated primordial follicle recruitment by increasing the percentage of primary and secondary follicles and decreasing the percentage of primordial follicles in the ovaries. Moreover, MEHP-induced ovarian oxidative stress by significantly increasing malondialdehyde (MDA) concentration and the expression of GSS and SOD1. When ovaries were co-administrated with MEHP and AA, follicle constitution was normalized, and the oxidative status was significantly decreased. These results suggested that AA ameliorated MEHP-induced ovarian oxidative stress and follicular dysregulation, which attested the clinical significance of AA for ovary protection in the case of MEHP exposure.

Role of Antioxidants in Alleviating Bisphenol A Toxicity

Bisphenol A (BPA) is an oestrogenic endocrine disruptor widely used in the production of certain plastics, e.g., polycarbonate, hard and clear plastics, and epoxy resins that act as protective coating for food and beverage cans. Human exposure to this chemical is thought to be ubiquitous. BPA alters endocrine function, thereby causing many diseases in human and animals. In the last few decades, studies exploring the mechanism of BPA activity revealed a direct link between BPA-induced oxidative stress and disease pathogenesis. Antioxidants, reducing agents that prevent cellular oxidation reactions, can protect BPA toxicity. Although the important role of antioxidants in minimizing BPA stress has been demonstrated in many studies, a clear consensus on the associated mechanisms is needed, as well as the directives on their efficacy and safety. Herein, considering the distinct biochemical properties of BPA and antioxidants, we provide a framework for understanding how antioxidants alleviate BPA-associated stress. We summarize the current knowledge on the biological function of enzymatic and non-enzymatic antioxidants, and discuss their practical potential as BPA-detoxifying agents.

Curcumin-loaded super-paramagnetic iron oxide nanoparticle affects on apoptotic factors expression and histological changes in a prepubertal mouse model of polycystic ovary syndrome-induced by dehydroepiandrosterone - A molecular and stereological study

AIMS

This study investigated the effects of curcumin-loaded super-paramagnetic iron oxide (Fe₃O₄) nanoparticles (NPs) (SPIONs) on histological parameters and apoptosis-inducing factors (AIFs) in an experimental mouse model of polycystic ovary syndrome (PCOS).

MATERIALS AND METHODS

A total number of 40 female prepuberal BALB/c mice were randomly divided into four groups. Group 1 was selected as control and Group 2 was considered as a vehicle taking sesame oil, in the form of a curcumin carrier. Moreover, Group 3 was administered with dehydroepiandrosterone (DHEA) at 6 mg/100 g of the body weight and Group 4 received the DHEA plus the NPs of curcumin (5.4 mg/100 g) for twenty consecutive days. Finally, histology, stereology, and apoptosis of the ovary were evaluated.

KEY FINDINGS

The results revealed that the NPs of curcumin had reduced ovarian volume (p < 0.05) and a total number of primary, secondary, antral, and primordial follicles in comparison with the PCOS and vehicle groups (p < 0.05). Furthermore, curcumin treatment following administration of the DHEA resulted in a significant decrease in BAX (p < 0.001) and levels of expression of Caspase3 (CASP3) protein, increased levels of B-cell lymphoma 2 (Bcl2) expression (p < 0.05), and moderated apoptosis in granulosa cells in comparison with the ones seen in the PCOS group.

SIGNIFICANCE

Ovarian injuries and DHEA-induced apoptosis were efficiently suppressed by curcumin, indicating the probable protective property of NPs of curcumin against PCOS.

The antioxidant curcumin postpones ovarian aging in young and middle-aged mice

Reproductive senescence is accompanied by a reduced number and quality of ovarian follicles in response to the accumulation of free radicals and the process of apoptosis. Having selected mice as models, we examined the hypothesis that curcumin as an antioxidant and anti-inflammatory agent might prevent or retard ovarian aging. Female NMRI 21-day-old mice were divided into control, vehicle and curcumin groups. In the treatment group the mice received curcumin at 100mgkg-1day-1 intraperitoneally. After 6, 12 and 33 weeks several parameters were examined including ovarian reserve, oocyte quality, oxidative status, invitro fertilisation and expression of ovulation-related (growth differentiation factor 9 (GDF-9) and bone morphogenetic protein 15 (BMP-15)) and anti-aging-related (sirtuin 1 (SIRT-1) and SIRT-3) genes. Curcumin treatment up to 12 and 33 weeks resulted in increased ovarian volume and number of follicles and was associated with elevated anti-Müllerian hormone and oestrogen and diminished FSH serum levels. Furthermore, enhanced oocyte maturation, fertilisation and embryo development plus reduced oxidative stress were seen in the curcumin group. Also, the expression of GDF-9, BMP-15, SIRT-1 and SIRT-3 genes was increased in the curcumin group. Concerning gestational age, the findings of the study suggested that administration of curcumin could delay the process of oocyte aging in a mouse model.

Vitamin C restores ovarian follicular reservation in a mouse model of aging

Ovarian aging is related to the reduction of oocyte quality and ovarian follicles reservation leading to infertility. Vitamin C is a natural antioxidant which may counteract with adverse effects of aging in the ovary. The aim of this study was to evaluate the possible effect of vitamin C on NMRI mice ovarian aging according to the stereological study. In this experimental study, 36 adult female mice (25-30 g) were divided into two groups: control and vitamin C. Vitamin C (150 mg/kg/day) were administered by oral gavage for 33 weeks. Six animals of each group were sacrificed on week 8, 12, and 33, and right ovary samples were extracted for stereology analysis. Our data showed that the total volume of ovary, cortex, medulla and corpus luteum were significantly increased in vitamin C group in comparison to the control groups (P≤0.05). In addition, the total number of primordial, primary, secondary, and antral follicles as well as granulosa cells were improved in vitamin C group in compared to the control groups (P≤0.05). No significant difference was observed in total volume of oocytes in antral follicles between control and vitamin C groups. Our data showed that vitamin C could notably compensate undesirable effects of ovarian aging in a mouse model.

Modulatory Effects of Single and Complex Vitamins on the In Vitro Growth of Murine Ovarian Follicles

Background

Vitamin is a well-known co-factor for many metabolic processes and its roles in fertility and follicular growth have been studied. Vitamin supplementation is frequently achieved by daily ingestion in the form of a complex capsule. However, the role of single and complex vitamins in in vitro maturation of murine follicles is not fully elucidated.

Methods

In this study, we evaluated the effects of two forms of vitamins. Pure L-ascorbic acid, and multi-vitamin (vitamin C + vitamin B complex) was treated at two different concentrations (50 and 100 µg/ml), to pre-puberty murine follicles during in vitro maturation. To determine the specific stage of growth that is affected by treatment with vitamins, the vitamins were treated from day 0, 4, 9, and 13. Growth of each follicle was assessed by measuring diameters of whole expanded area and of the granulosa cells. Expression of follicular and oocyte growth-related genes and the effect of vitamin on the viability of follicles was assessed using senescence associated β-galactosidase staining.

Results

Treatment with vitamins promoted the in vitro growth of murine follicles and the upregulated the expression of granulosa cell- and oocyte-specific genes such as BMP15, Fsh receptor, and GDF9. The proliferation of the granulosa cells was enhanced by the treatment of vitamin. Fifty µg/ml concentration vitamin showed greater effects compared to higher concentration. The viability of in vitro grown follicles was also significantly improved in vitamin-treated follicles. The effects of single L-ascorbic acid and complex vitamin were not significantly different to those of day 4 and day 9 follicles. Vitamins promoted murine follicle development in vitro with different effects on specific growth stage.

Conclusion

Supplementation of vitamins during in vitro maturation of murine follicles is an efficient strategy for in vitro expansion of follicular cells. These results could be customized to the sophisticated culture of follicles retrieved from aged or cancer-survived female that contain smaller number of follicles with reduced potential to develop into mature follicles.

Vitamin C protects against defects induced by juglone during porcine oocyte maturation

Juglone, a naphthoquinone isolated from many species of the Juglandaceae family, has been used in traditional Chinese medicine for centuries because of its antiviral, antibacterial, and antitumor activities. However, the toxicity of juglone has also been demonstrated. Here, we used porcine oocytes as a model to explore the effects of juglone on oocyte maturation and studied the impact of vitamin C (VC) administration on juglone exposure-induced meiosis defects. Exposure to juglone significantly restricted cumulus cell expansion and decreased the first polar body extrusion. In addition, juglone exposure disturbed spindle organization, actin assembly, and the distribution of mitochondria during oocyte meiosis, while the acetylation level of α-tubulin was also reduced. These defects were all ameliorated by VC administration. Our findings indicate that juglone exposure induced meiotic failure in porcine oocytes, while VC protected against these defects during porcine oocyte maturation by ameliorating the organization of the cytoskeleton and mitochondrial distribution.

Long-term exposure to very low doses of bisphenol S affects female reproduction

Bisphenols belong to the endocrine disruptors, affecting reproduction even in extremely low doses. Bisphenol S (BPS) has become widely used as a substitute for the earlier-used bisphenol A; however, its harmlessness is questionable. The aim of this study was to evaluate the effect of BPS on folliculogenesis and oocyte quality after in vivo exposure to low doses of BPS. Four-week-old ICR females (n = 16 in each experimental group) were exposed to vehicle control (VC), BPS1 (0.001 ng BPS.g/bw/day), BPS2 (0.1 ng.g/bw/day), BPS3 (10 ng.g/bw/day) and BPS4 (100 ng.g/bw/day) for 4 weeks. Ovaries were subjected to stereology and nano liquid chromatography-mass spectrometry (LC/MS). Simultaneously, metaphase II oocytes were obtained after pregnant mare serum gonadotrophin and human chorionic gonadotrophin administration, followed by immunostaining. In particular, mating and two-cell embryo flushing were performed. We observed that BPS decreases the amount of ovarian follicles and BPS2 (0.1 ng.g/bw/day) affects the volume of antral follicles. Accordingly, ovarian proteome is affected after BPS2 treatment. While BPS2 dosing results mainly in cytoskeletal damage in matured oocytes, the effects of BPS3 and BPS4 seem to be due instead to epigenetic alterations in oocytes. Arguably, these changes lead to observed affection of in vivo fertilization rate after BPS3 and BPS4 treatment. BPS significantly affects female reproduction astoundingly in extremely low doses. These findings underline the necessity to assess the risk of ongoing BPS exposure for public health.