Effects of Environment and Lifestyle Factors on Anovulatory Disorder

Hexavalent Chromium Disrupts Oocyte Development in Rats by Elevating Oxidative Stress, DNA Double-Strand Breaks, Microtubule Disruption, and Aberrant Segregation of Chromosomes

Environmental and occupational exposure to hexavalent chromium, Cr(VI), causes female reproductive failures and infertility. Cr(VI) is used in more than 50 industries and is a group A carcinogen, mutagenic and teratogenic, and a male and female reproductive toxicant. Our previous findings indicate that Cr(VI) causes follicular atresia, trophoblast cell apoptosis, and mitochondrial dysfunction in metaphase II (MII) oocytes. However, the integrated molecular mechanism of Cr(VI)-induced oocyte defects is not understood. The current study investigates the mechanism of Cr(VI) in causing meiotic disruption of MII oocytes, leading to oocyte incompetence in superovulated rats. Postnatal day (PND) 22 rats were treated with potassium dichromate (1 and 5 ppm) in drinking water from PND 22-29 and superovulated. MII oocytes were analyzed by immunofluorescence, and images were captured by confocal microscopy and quantified by Image-Pro Plus software, Version 10.0.5. Our data showed that Cr(VI) increased microtubule misalignment (~9 fold), led to missegregation of chromosomes and bulged and folded actin caps, increased oxidative DNA (~3 fold) and protein (~9-12 fold) damage, and increased DNA double-strand breaks (~5-10 fold) and DNA repair protein RAD51 (~3-6 fold). Cr(VI) also induced incomplete cytokinesis and delayed polar body extrusion. Our study indicates that exposure to environmentally relevant doses of Cr(VI) caused severe DNA damage, distorted oocyte cytoskeletal proteins, and caused oxidative DNA and protein damage, resulting in developmental arrest in MII oocytes.

Gonadal bacterial community composition is associated with sex-specific differences in swamp eels (Monopterus albus)

Organisms are colonized by microorganism communities and play a pivotal role in host function by influencing physiology and development. In mammals, bacterial community may alter gonadal maturation and drive sex-specific differences in gene expression and metabolism. However, bacterial microbiota diversity in the gonads of early vertebrates has not been fully elucidated. Here, we focused on the swamp eel (Monopterus albus), which naturally undergoes sex reversal, and systematically analyzed the bacterial microbiota profiles between females and males using 16S rRNA gene sequences. Specifically, the microbial abundance and community diversity of gonads in males were higher than in females. Although Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria were characterized as the dominating phyla in ovary and testis, the relative abundance of Firmicutes was significantly higher in males than females. Detailed analysis of the microbial community revealed that Bacilli were the dominant bacteria in ovaries and Clostridium in testes of M. albus. More importantly, we proposed that differences in the microbial composition and distribution between ovaries and testes may be linked to functional categories in M. albus, especially metabolism. These findings represent a unique resource of bacterial community in gonads to facilitate future research about the mechanism of how microbiota influence sex-specific differences and sex reversal in vertebrates.

Clinical efficacy of Wenjing decoction in the treatment of ovulatory disorder infertility: A systematic review and meta-analysis

OBJECTIVES

Wenjing decoction (WJD) was widely used in the treatment for ovulatory disorder infertility (ODI) in China, while its efficacy was not clearly known. In this study, we evaluated the clinical efficacy of WJD by meta-analysis.

METHODS

Eight electronic databases including Cochrane Library, PubMed, Embase, Web of Science, China National Knowledge Infrastructure, WanFang Data, VIP Database, and China Biology Medicine were searched for randomized controlled trials (RCTs) published from the inception of each database to July 1, 2021, of which the interventions involve WJD and clomiphene. Outcomes included clinical efficacy rate, pregnancy rate, ovulation rate, dominant follicle diameter, endometrial thickness, estradiol, follicle-stimulating hormone, and luteinizing hormone. Meta-analysis and risk of bias were performed by RevMan 5.3 software.

RESULTS

Eleven RCTs including 915 patients, of which 476 in the intervention group and 439 in the control group. Meta-analysis showed that WJD was better than clomiphene for patients with ODI in terms of clinical effective rate (odds ratio [OR] = 1.22, 95% confidence interval [CI]: 1.08-1.34), pregnancy rate (OR = 1.54, 95% CI: 1.15-2.07), ovulation rate (OR = 1.34, 95% CI: 1.07-1.67), endometrial thickness (mean difference [MD] = 1.50, 95% CI: 0.90-2.10), and dominant follicle diameter (MD = 1.85, 95% CI: 0.68-3.02). The estradiol level (MD = 91.0, 95% CI: 80.3-101.88) in patients taking WJD was significantly higher than those taking clomiphene, while the follicle-stimulating hormone level (MD = -0.93, 95% CI: -1.13 to -0.72) and the luteinizing hormone level (MD = -4.41, 95% CI: -4.80 to -4.03) in patients taking WJD was significantly lower than those taking clomiphene. Our results also indicated that WJD combined with clomiphene was better than clomiphene alone for patients with ODI in terms of pregnancy rate (OR = 1.79, 95% CI: 1.37-2.35).

CONCLUSIONS

WJD may be effective in the treatment of patients with ODI. Due to the quality and quantity of literature, RCT with large sample size and high quality need to be performed to verify our conclusion.

Reprotoxic Impact of Environment, Diet, and Behavior

Reproductive health is progressively declining due to multiples endogenous and exogenous factors, such as environmental contaminants, diet and behavior. Accumulated evidences confirm that fertility and reproductive function have been adversely affected by exposure to chemical contaminants released in the environment. Today, the impact of diet and behavior on reproductive processes is also receiving special attention from the scientific community. Indeed, a close relationship between diet and fertility has been proven. Furthermore, a combination of unhealthy behavior, such as exposure to hazardous compounds and stress factors, poses living organisms at higher risk of reprotoxic effects. In particular, it has been described that poor life behaviors are associated with reduced male and female fertility due to decreased gamete quality and function. Most of the erroneous behaviors are, furthermore, a source of oxidative stress that, leading to epigenetic alterations, results in an impaired reproductive fitness. This review reports the detrimental impact of the most common environmental chemical stressors, diet, and behavior on reproductive functionality and success. Although clear evidences are still scarce, reassuring data are provided that a healthy diet and reverting unhealthy lifestyles may be of help to recover physiological reproductive conditions.

Low Doses of Resveratrol Protect Human Granulosa Cells from Induced-Oxidative Stress

Resveratrol is a phytoalexin present in plant-derived foods, including grape’s skin, cocoa, and peanuts. Evidence suggests that it has beneficial effects on human health because of its antioxidant properties. However, there is limited knowledge about the part played by resveratrol in ovarian function. In this paper, the influence of resveratrol on granulosa cells (GC) was evaluated. In addition to being the main estradiol producers, GC are in direct contact with the oocyte, playing a fundamental role in its growth and development. The cell line COV434 and human granulosa cells (hGC), obtained from women undergoing assisted reproductive technology (ART), were used. GC were treated with resveratrol (0.001–20 μM) at different times (24–72 h). Low concentrations of this compound suggest a protective role, as they tend to reduce ROS/RNS formation after inducement of stress. On the contrary, high concentrations of resveratrol affect GC viability and steroidogenic function. As it may act as a direct modulator of GC oxidative balance, this work may help to clarify the impact of resveratrol on GC and the usefulness of this antioxidant as adjunct to infertility treatments.