It is well established that age-related decline of the biological capacity of a woman to reproduce is primarily related to the poor developmental potential of her gametes. This renders female ageing the most significant determinant of success in IVF. Starting with a reference picture of the main molecular and cellular failures of aged oocytes, granulosa cells and follicular microenvironment, this review focuses on age-related biochemical mechanisms underlying these changes. According to the most relevant concept of ageing, age-associated malfuction results from physiological accumulation of irreparable damage to biomolecules as an unavoidable side effect of normal metabolism. More than a decade after the free radical theory of ovarian ageing, biological and clinical research supporting the involvement of oxidative injuries in follicle ageing is discussed. Looking for the aetiology of oxidative stress, we consider the effect of ageing on ovarian and follicular vascularization. Then, we propose a potential role of advanced glycation end-products known to be involved in the physiological ageing of most tissues and organs. We conclude that future investigation of age-related molecular damage in the different ovarian components will be imperative in order to evaluate the possibility to save or rescue the developmental potential of aged oocytes.
Limited knowledge exists about changes in follicle quality associated with age. The aim of this work was to investigate whether ageing may cause oxidative stress-mediated alterations in human granulosa cells (GCs) from periovulatory follicles. GCs employed in this study were obtained from follicular aspirates of 20 younger women (range 27–32 years) and 20 older women (range 38–41 years) undergoing an IVF treatment. Results obtained from comparative RT–PCR analysis revealed that the mean relative levels of mRNAs coding for superoxide dismutases, Cu, ZnSOD (SOD1), MnSOD (SOD2) and catalase were significantly decreased in women ≥38 years (P < 0.05, Student’s t-test). These changes were associated with a reduced expression of SOD1, SOD2 and catalase at the protein level. When examined at an ultrastructural level, most of the GCs from this group showed defective mitochondria and fewer lipid droplets than those observed in the younger group. These results indicate that GCs from older patients suffer from age-dependent oxidative stress injury and are taken as an evidence for reduced defence against reactive oxygen species (ROS) in GCs during reproductive ageing.
The aim of this work was to study the antioxidant enzymatic defences in human follicular fluid and investigate their possible changes during reproductive ageing. To this end, we tested the specific activities and protein expression of enzymes involved in reactive oxygen species (ROS) scavenging and in detoxification of ROS byproducts in follicular fluid from young (range 27–32 years, n = 12) and older (range 39–45 years, n = 12) women participating in an IVF programme. Results show that all the tested enzymes [superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione transferase, glutathione reductase] were significantly expressed in human follicular fluid. However, when the two age groups were compared, we found that follicular fluid from older women exhibited a reduced level of glutathione transferase and catalase activities and a higher level of SOD activity. Immunoblot analysis revealed that ageing was associated with decreased protein expression of GST Pi isoform and did not affect SOD and catalase protein expression. Taken together, these findings indicate that reproductive ageing is accompanied by a change in the antioxidant enzymatic pattern that could impair ROS scavenging efficiency in the follicular environment.
2 December 2018 in Reproductive Biology and Endocrinology
There is growing evidence that lifestyle choices account for the overall quality of health and life (QoL) reflecting many potential lifestyle risks widely associated with alterations of the reproductive function up to the infertility. This review aims to summarize in a critical fashion the current knowledge about the potential effects of stress and QoL on female reproductive function. A specific literature search up to August 2017 was performed in IBSS, SocINDEX, Institute for Scientific Information, PubMed, Web of Science and Google Scholar. Current review highlights a close relationship in women between stress, QoL and reproductive function, that this association is more likely reported in infertile rather than fertile women, and that a vicious circle makes them to have supported each other. However, a precise cause-effect relationship is still difficult to demonstrate due to conflicting results and the lack of objective measures/instruments of evaluation.
The potential hazardous effects that estrogen- and androgen-like chemicals may have both on wildlife and human health have attracted much attention from the scientific community. Endocrine disruptors (EDCs) are chemicals that have the capacity to interfere with normal signalling systems. EDCs may mimic, block or modulate the synthesis, release, transport, metabolism and binding or elimination of natural hormones. Even though potential EDCs may be present in the environment at only very low levels, they may still cause harmful effects, especially when several different compounds act on one target. EDCs include persistent pollutants, agrochemicals and widespread industrial compounds. Not all EDCs are man-made compounds; many plants produce substances (phytoestrogens) that can have different endocrine effects either adverse or beneficial in certain circumstances. Natural substances such as sex hormones from urban or farm wastes can become concentrated in industrial, agricultural and urban areas; thus, such wastes may be considered potential ‘EDCs’ for humans and/or wildlife. Much attention has focussed on changing trends in male reproductive parameters in relation to EDC exposure; however, studies on the female reproductive system have been less comprehensive. We have focussed this article on four major aspects of female reproductive health: fertility and fecundability, endometriosis, precocious puberty and breast and endometrial cancer.
There is significant evidence that continuous and prolonged exposure to several endocrine disrupting chemicals (EDC) is a risk factor for reduced fertility and fecundity in women. There is also evidence that ED exposure has trans-generational effects. In this systematic review, we evaluate the evidence for an association between EDC exposure and women's reproductive health. Studies were found by searching the PubMed database for articles published up to 2010. Associations between ED exposure and women's reproductive health reported in the PubMed database are summarized and classified as fertility and fecundity, pregnancy outcomes, transgenerational exposure and effects. Epidemiological studies on EDCs are not always consistent, in part due to limitations imposed by practical constraints. In order to make progress in this field, we recommend taking advantage of biomonitoring and biobanks, including the development of appropriate biomarkers, and taking into greater consideration modulating factors such as genetic polymorphisms and dietary habits. Further human studies are warranted with particular focus on impaired fertility/fecundity associated with currently widespread ED (e.g. bisphenol A, phthalates and polybrominated flame retardants). A detailed appraisal of compounds specifically related to adverse reproductive outcomes is very important for prevention and risk-communication strategies. Besides research needs, the current evidence is sufficient to prompt precautionary actions to protect women's reproductive health.