Cellular and molecular aspects of ovarian follicle ageing

Ovarian aging and premature ovarian failure

Physiological reproductive aging occurs as a result of a decrease in the number and quality of oocytes in ovarian cortex follicles. Although the reason for the decrease in the quality of the pool and follicular oocytes is not fully understood, endocrine, paracrine, genetic, and metabolic factors are thought to be effective. Nowadays, in order to understand the mechanisms of ovarian aging, genomic research has gained importance. The effect of co-factors, such as telomerase and ceramide, in the ovarian aging process is only getting ascertained with new research studies. The most important tests in the assessment of ovarian aging are antral follicle count and anti-Mullerian hormone.

3,4-Dihydroxybenzaldehyde Derived from Prunus mume Seed Inhibits Oxidative Stress and Enhances Estradiol Secretion in Human Ovarian Granulosa Tumor Cells

Granulosa cells form ovarian follicles and play important roles in the growth and maturation of oocytes. The protection of granulosa cells from cellular injury caused by oxidative stress is an effective therapy for female infertility. We here investigated an effective bioactive compound derived from Prunus mume seed extract that protects granulosa cells from hydrogen peroxide (H2O2)-induced apoptosis. We detected the bioactive compound, 3,4-dihydroxybenzaldehyde (3,4-DHBA), via bioactivity-guided isolation and found that it inhibited the H2O2-induced apoptosis of granulosa cells. We also showed that 3,4-DHBA promoted estradiol secretion in granulosa cells and enhanced the mRNA expression levels of steroidogenic factor 1, a promoter of key steroidogenic enzymes. These results suggest that P. mume seed extract may have clinical potential for the prevention and treatment of female infertility.

SIRT1 signalling protects mouse oocytes against oxidative stress and is deregulated during aging

STUDY QUESTION

Is SIRT1 involved in the oxidative stress (OS) response in mouse oocytes?

SUMMARY ANSWER

SIRT1 plays a pivotal role in the adaptive response of mouse germinal vesicle (GV) oocytes to OS and promotes a signalling cascade leading to up-regulation of the MnSod gene.

WHAT IS KNOWN ALREADY

OS is known to continuously threaten acquisition and maintenance of oocyte developmental potential during in vivo processes and in vitro manipulations. Previous studies in somatic cells have provided strong evidence for the role of SIRT1 as a sensor of the cell redox state and a protector against OS and aging.

STUDY DESIGN, SIZE, DURATION

GV oocytes obtained from young (4-8 weeks) and reproductively old (48-52 weeks) CD1 mice were blocked in the prophase stage by 0.5 µM cilostamide. Groups of 30 oocytes were exposed to 25 µM H2O2 and processed following different times for the analysis of intracellular localization of SIRT1 and FOXO3A, and evaluation of Sirt1, miRNA-132, FoxO3a and MnSod gene expression. Another set of oocytes was cultured in the presence or absence of the SIRT1-specific inhibitor Ex527, and exposed to H2O2 in order to assess the involvement of SIRT1 in the activation of a FoxO3a-MnSod axis and ROS detoxification. In the last part of this study, GV oocytes were maturated in vitro in the presence of different Ex527 concentrations (0, 2.5, 5, 10, 20 µM) and assessed for maturation rates following 16 h. Effects of Ex527 on spindle morphology and ROS levels were also evaluated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

SIRT1 and FOXO3A intracellular distribution in response to OS was investigated by immunocytochemistry. Real-time RT-PCR was employed to analyse Sirt1, miR-132, FoxO3a and MnSod gene expression. Reactive oxygen species (ROS) production was evaluated by in vivo measurement of carboxy-H2DCF diacetate labelling. Spindle and chromosomal distribution in in vitro matured oocytes were analysed by immunocytochemistry and DNA fluorescent labelling, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

Specific changes in the intracellular localization of SIRT1 and up-regulation of Sirt1 gene were detected in mouse oocytes in response to OS. Moreover, increased intracellular ROS were observed when SIRT1 activity was inhibited by Ex527. In aged oocytes Sirt1 was expressed more than in young oocytes but SIRT1 protein was undetectable. Upon OS, significant changes in miR-132 micro-RNA, a validated Sirt1 modulator, were observed. A negative correlation between Sirt1 mRNA and miR-132 levels was observed when young oocytes exposed to OS were compared with young control oocytes, and when aged oocytes were compared with young control oocytes. FoxO3a and MnSod transcripts were increased upon OS with the same kinetics as Sirt1 transcripts, and up-regulation of MnSod gene was prevented by oocyte treatment with Ex527, indicating that SIRT1 acts upstream to the FoxO3a-MnSod axis. Finally, the results of the in vitro maturation assay suggested that SIRT1 might be involved in oocyte maturation by regulating the redox state and ensuring normal spindle assembly.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study was the absence of direct quantification of SIRT1 enzymatic activity due to the lack of an appropriately sensitive method.

WIDER IMPLICATIONS OF THE FINDINGS

The present findings may provide a valuable background for studying the regulation of SIRT1 during oogenesis and its relevance as a sensor of oocyte redox state and energy status. The antioxidant response orchestrated by SIRT1 in oocytes seems to decrease with aging. This suggests that SIRT1 could be an excellent pharmacological target for improving oocyte quality and IVF outcome in aging or aging-like diseases.

STUDY FUNDING/COMPETING INTERESTS

The work was supported by the Ministero dell'Università e della Ricerca Scientifica (MIUR) to C.T., F.A., C.D., A.M.D. The authors declare no conflict of interest.

Lifestyle and Advanced Glycation End Products (AGEs) Burden: Its Relevance to Healthy Aging

Uncontrolled continued exposure to oxidative stress is a precursor to many chronic diseases including cancer, diabetes, degenerative disorders and cardiovascular diseases. Of the many known mediators of oxidative stress, reactive oxygen species (ROS) and advanced glycation end products (AGEs) are the most studied. In the present review, we have summarized current data on the origin of circulating AGEs, discussed issues associated with reliable assessment of its steady state level, and changes in its level with age and select metabolic diseases. Lastly, we have made recommendations about life style changes that may decrease AGEs burden to promote healthy aging.

Female reproductive aging is master-planned at the level of ovary

The ovary receives a finite pool of follicles during fetal life. Atresia remains the major form of follicular expenditure at all stages since development of ovary. The follicular reserve, however, declines at an exponential rate leading to accelerated rate of decay during the years preceding menopause. We examined if diminished follicle reserve that characterizes ovarian aging impacts the attrition rate. Premature ovarian aging was induced in rats by intra-embryonic injection of galactosyltransferase-antibody on embryonic day 10. On post-natal day 35 of the female litters, either a wedge of fat (sham control) or a wild type ovary collected from 25-day old control rats, was transplanted under the ovarian bursa in both sides. Follicular growth and atresia, and ovarian microenvironment were evaluated in the follicle-deficient host ovary and transplanted ovary by real time RT-PCR analysis of growth differentiation factor-9, bone morphogenetic protein 15, and kit ligand, biochemical evaluation of ovarian lipid peroxidation, superoxide dismutase (SOD) and catalase activity, and western blot analysis of ovarian pro- and anti-apoptotic factors including p53, bax, bcl2, and caspase 3. Results demonstrated that the rate of follicular atresia, which was highly preponderant in the follicle-deficient ovary of the sham-operated group, was significantly prevented in the presence of the transplanted ovary. As against the follicle-deficient ovary of the sham-operated group, the follicle-deficient host ovary as well as the transplanted ovary in the ovary-transplanted group exhibited stimulated follicle growth with increased expression of anti-apoptotic factors and down regulation of pro-apoptotic factors. Both the host and transplanted ovaries also had significantly lower rate of lipid peroxidation with increased SOD and catalase activity. We conclude that the declining follicular reserve is perhaps the immediate thrust that increases the rate of follicle depletion during the final phase of ovarian life when the follicle reserve wanes below certain threshold size.

Autophagy in the endocrine glands

Autophagy is an important cellular process involving the degradation of intracellular components. Its regulation is complex and while there are many methods available, there is currently no single effective way of detecting and monitoring autophagy. It has several cellular functions that are conserved throughout the body, as well as a variety of different physiological roles depending on the context of its occurrence in the body. Autophagy is also involved in the pathology of a wide range of diseases. Within the endocrine system, autophagy has both its traditional conserved functions and specific functions. In the endocrine glands, autophagy plays a critical role in controlling intracellular hormone levels. In peptide-secreting cells of glands such as the pituitary gland, crinophagy, a specific form of autophagy, targets the secretory granules to control the levels of stored hormone. In steroid-secreting cells of glands such as the testes and adrenal gland, autophagy targets the steroid-producing organelles. The dysregulation of autophagy in the endocrine glands leads to several different endocrine diseases such as diabetes and infertility. This review aims to clarify the known roles of autophagy in the physiology of the endocrine system, as well as in various endocrine diseases.

Dicarbonyl stress and glyoxalases in ovarian function

The ovary is the main regulator of female fertility. Changes in maternal health and physiology can disrupt intraovarian homoeostasis thereby compromising oocyte competence and fertility. Research has only recently devoted attention to the involvement of dicarbonyl stress in ovarian function. On this basis, the present review focuses on clinical and experimental research supporting the role of dicarbonyl overload and AGEs (advanced glycation end-products) as key contributors to perturbations of the ovarian microenvironment leading to lower fertility. Particular emphasis has been given to oocyte susceptibility to methylglyoxal, a powerful glycating agent, whose levels are known to increase during aging and metabolic disorders. According to the literature, the ovary and the oocyte itself can rely on the glyoxalase system to counteract the possible dicarbonyl overload such as that which may occur in reproductive-age women and patients with PCOS (polycystic ovarian syndrome) or diabetes. Overall, although biochemical methods for proper evaluation of dicarbonyl stress in oocytes and the ovarian microenvironment need to be established, AGEs can be proposed as predictive markers and/or therapeutic targets in new strategies for improving reproductive counselling and infertility therapies.

Female dietary antioxidant intake and time to pregnancy among couples treated for unexplained infertility

OBJECTIVE

To determine whether increased antioxidant intake in women is associated with shorter time to pregnancy (TTP) among a cohort of couples being treated for unexplained infertility.

DESIGN

Secondary data analysis of a randomized controlled trial.

SETTING

Academic medical center associated with a private infertility center.

PATIENTS

Females with unexplained infertility.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE(S)

The time it took to establish a pregnancy that led to a live birth.

RESULT(S)

Mean nutrient intake exceeded the estimated average requirement (EAR) for vitamins C and E. No differences in mean intake of any of the antioxidants were noted between women who delivered a live-born infant during the study period vs. those who did not. In multivariable models, intake of β-carotene from dietary supplements was associated with shorter TTP among women with body mass index (BMI) ≥25 kg/m(2) (hazard ratio [HR] 1.29, 95% confidence interval [CI] 1.09-1.53) and women <35 y (HR 1.19, 95% CI 1.01-1.41). Intake of vitamin C from dietary supplements was associated with shorter TTP among women with BMI <25 kg/m(2) (HR 1.09, 95% CI 1.03-1.15) and women <35 y (HR 1.10, 95% CI 1.02-1.18). Intake of vitamin E from dietary supplements among women ≥35 y also was associated with shorter TTP (HR 1.07, 95% CI 1.01-1.13).

CONCLUSION(S)

Shorter TTP was observed among women with BMI <25 kg/m(2) with increasing vitamin C, women with BMI ≥25 kg/m(2) with increasing β-carotene, women <35 y with increasing β-carotene and vitamin C, and women ≥35 y with increasing vitamin E.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00260091.

Ovarian aging-like phenotype in the hyperandrogenism-induced murine model of polycystic ovary

There are prominently similar symptoms, effectors, and commonalities in the majority of characteristics between ovarian aging and polycystic ovarian syndrome (PCOS). Despite the approved role of oxidative stress in the pathogenesis of PCOS and aging, to our knowledge, the link between the PCO(S) and aging has not been investigated yet. In this study we investigated the possible exhibition of ovarian aging phenotype in murine model of PCO induced by daily oral administration of letrozole (1 mg/kg body weight) for 21 consecutive days in the female Wistar rats. Hyperandrogenization showed irregular cycles and histopathological characteristics of PCO which was associated with a significant increase in lipid peroxidation (LPO) and reactive oxygen species (ROS) and decrease in total antioxidant capacity (TAC) in serum and ovary. Moreover, serum testosterone, insulin and tumor necrosis factor-alpha (TNF-α) levels, and ovarian matrix metalloproteinase-2 (MMP-2) were increased in PCO rats compared with healthy controls, while estradiol and progesterone diminished. Almost all of these findings are interestingly found to be common with the characteristics identified with (ovarian) aging showing that hyperandrogenism-induced PCO in rat is associated with ovarian aging-like phenotypes. To our knowledge, this is the first report that provides evidence regarding the phenomenon of aging in PCO.

Follicular fluid soluble receptor for advanced glycation end-products (sRAGE): a potential indicator of ovarian reserve

CONTEXT

The interaction of advanced glycation end-products (AGEs) with their cellular receptor (RAGE) is implicated in the pathogenesis of abnormal ovarian follicular growth. RAGE has a circulating secretory receptor form, soluble RAGE (sRAGE), which neutralizes the action of AGEs and might exert a protective role on the follicular environment.

OBJECTIVE

The objective of the study was to investigate whether serum or follicular fluid (FF) sRAGE levels are associated with markers of ovarian reserve.

DESIGN, SETTING, AND PARTICIPANTS

Serum anti-Mullerian hormone (AMH) and sRAGE protein levels were correlated in 31 reproductive-aged women. An additional 33 women who underwent oocyte retrieval for in vitro fertilization were enrolled. AMH and its receptor (AMHR-II) mRNA levels were quantified in cumulus granulosa cells and FF sRAGE and AMH protein levels were measured.

MAIN OUTCOME MEASURES

Granulosa cell AMH and AMHR-II gene expression, serum and FF AMH and sRAGE protein concentration, and number of oocytes retrieved were measured.

RESULTS

In the serum, sRAGE levels were negatively correlated with body mass index (BMI) (r = -0.5, P < .001) but not with age or serum AMH. The higher the FF sRAGE, the lower the number of international units of gonadotropin needed per cycle independent of age, BMI, or day 3 FSH level (r = -0.4, P = .04). After adjusting for age, BMI, day 3 FSH, and the total dose of gonadotropins, FF sRAGE predicted the number of oocytes retrieved (R(2) = 0.27, P = .045). FF sRAGE positively correlated with FF AMH levels (r = 0.5, P = .0085). RT-PCR results showed no correlation between the FF sRAGE and AMH or AMHR-II mRNA levels.

CONCLUSION

These data support a relationship between FF sRAGE and measures of ovarian reserve. The pathological significance of the harmful inflammatory AGEs in follicular health clearly requires further investigation. Targeting AGEs might offer potential therapeutic options for the treatment of diminished ovarian response.

Age-associated telomere shortening in mouse oocytes

BACKGROUND

Oocytes may undergo two types of aging. The first is induced by exposure to an aged ovarian microenvironment before being ovulated, known as 'reproductive or maternal aging', and the second by either a prolonged stay in the oviduct before fertilization or in vitro aging prior to insemination, known as 'postovulatory aging'. However, the molecular mechanisms underlying these aging processes remain to be elucidated. As telomere shortening in cultured somatic cells triggers replicative senescence, telomere shortening in oocytes during reproductive and postovulatory aging may predict developmental competence. This study aimed to ascertain the mechanisms underlying altered telomere biology in mouse oocytes during reproductive and postovulatory aging.

METHODS

We studied Tert expression patterns, telomerase activity, cytosolic reactive oxygen species (ROS) production, and telomere length in fresh oocytes from young versus reproductively-aged female mice retrieved from oviducts at 14 h post-human chorionic gonadotropin (hCG), in vivo or in vitro postovulatory-aged mouse oocytes at 23 h post-hCG. Oocytes were collected from super-ovulated C57BL/6 J mice of 6-8 weeks or 42-48 weeks of age. mRNA and protein expressions of the Tert gene were quantified using real-time quantitative reverse transcriptase polymerase chain reaction (Q-PCR) and immunochemistry. Telomerase activity was measured by a telomeric repeat amplification protocol assay, while telomere length was measured by Q-PCR and quantitative fluorescence in situ hybridization analyses.

RESULTS

The abundance of Tert expression in oocytes significantly decreased during reproductive and postovulatory aging. Immunofluorescent staining clearly demonstrated an altered pattern and intensity of TERT protein expression in oocytes during reproductive aging. Furthermore, relative telomerase activity (RTA) in oocytes from reproductively-aged females was significantly lower than that in oocytes from young females. In contrast, RTA in postovulatory-aged oocytes was similar to that in fresh oocytes. Oocytes from reproductively-aged females and postovulatory-aged oocytes showed higher ROS levels than oocytes from young females. Relative telomere length (RTL) was remarkably shorter in oocytes from reproductively-aged females compared to oocytes from young females. However, postovulatory aging had no significant effect on RTL of oocytes.

CONCLUSIONS

Long-term adverse effects of low telomerase activity and increased ROS exposure are likely associated with telomere shortening in oocytes from reproductively-aged female mice.

Conventional IVF as a laboratory strategy to rescue fertility potential in severe poor responder patients: the impact of reproductive aging

OBJECTIVE

To investigate whether laboratory strategies can improve in vitro fertilization (IVF) outcome in poor responder patients. We compared the effectiveness of conventional IVF and intra cytoplasmic sperm injection (ICSI) in assisted reproductive technologies cycles in which only one or two oocytes were retrieved at ovarian pick up, in the absence of male infertility.

DESIGN

Retrospective analysis of 425 cycles in 386 poor responder patients.

INTERVENTION(S)

Standard stimulation protocol with gonadotropins and gonadotropin releasing hormone (GnRH) antagonist.

MAIN OUTCOME MEASURE(S)

Fertilization rate, cleavage rate, good-quality embryo rate, implantation rate, clinical pregnancy rate (PR) and miscarriage rate.

RESULTS

IVF was found to be more advantageous for implantation and PR, especially in patients under 35 years and in women aged between 35 and 38 years. No differences were noted in the other parameter evaluated. Patients aged over 38 years showed no difference using the two techniques.

CONCLUSION

The employment of ICSI in the absence of a male factor can reduce reproductive outcome in poor responder. Probably because of aging-related defects overcoming the advantage of sperm selection, the choice of IVF technique is not relevant to reproductive success when oocyte quality is compromised by reproductive aging. Although further randomized trials are needed to confirm our results, we propose that, in absence of male infertility, conventional IVF might be the technique of choice in young patients, especially in those aged below 35 years.

Advanced glycation end products and their relevance in female reproduction

STUDY QUESTION

Do advanced glycation end products (AGEs) and their receptors play a role in female reproduction?

SUMMARY ANSWER

AGEs might contribute to the etiology of polycystic ovary syndrome (PCOS) and infertility.

WHAT IS KNOWN ALREADY

The endogenous AGEs are produced in the body by chemical reactions. Exogenous sources of AGEs are diet and smoking. AGEs have been proposed to be among the main intermediaries involved in several diseases, such as metabolic syndrome, type 2 diabetes mellitus, cardiovascular disease, ovarian aging, inflammation, neurodegenerative disorders and PCOS.

STUDY DESIGN, SIZE, DURATION

A systematic review was performed for all available basic science and clinical peer-reviewed articles published in PubMed from 1987 to date. Abstracts of annual meetings of the Endocrine Society and American Society for Reproductive Medicine were also reviewed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 275 publications and scientific abstracts were identified from the initial search. Sixty-two papers and four published scientific abstracts were selected for full review. The main outcomes were the regulatory effects of AGEs on: (i) granulosa cells, adipocyte physiology, obesity and insulin resistance in women with PCOS and in polycystic ovary animal models and (ii) infertility and measures of ovarian reserve.

MAIN RESULTS AND THE ROLE OF CHANCE

There is an intricate relationship between the AGE-RAGE (receptor for AGEs) system and some aspects of PCOS, such as granulosa cell dysfunction, adipocyte pathophysiology, obesity and insulin resistance. Additionally, irregular ovarian AGE signaling might in part explain the abnormal ovarian histology observed in women with PCOS. The ovarian dysfunction due to AGEs in women without PCOS suggests a role for the AGE-RAGE system in the ovarian follicular environment, and might relate to assisted reproduction technology outcome and measures of ovarian reserve.

LIMITATIONS, REASONS FOR CAUTION

The body of literature currently available limits these findings. The results obtained from granulosa cell lines and animal models may not fully extrapolate to humans.

WIDER IMPLICATIONS OF THE FINDINGS

This review underscores a critical need to unveil the exact mechanistic actions of AGEs in reproductive physiology and more specifically the hypothalamic-pituitary-ovarian axis. AGE inhibitors might present an emerging therapeutic approach with significant applications in the context of PCOS and infertility.

STUDY FUNDING/COMPETING INTEREST(S)

American Society for Reproductive Medicine New Investigator Award and University of Vermont College of Medicine Internal Funds. No competing interests.

Targeting angiogenesis in the pathological ovary

The ovary is a key tissue in the study of physiological neo-vascularisation in the adult and its study has highlighted important molecules involved in the regulation of angiogenesis in vivo. These include vascular endothelial growth factor, delta-like ligand 4, thrombospondin-1, prokineticin-1 and prostaglandin E2. Targeting these molecular pathways has therapeutic potential and their manipulation has an increasing preclinical and clinical role in the management of the pathological ovary. Targeting angiogenic pathways has utility in the promotion of ovarian angiogenesis to improve tissue and follicle survival and function as well as the prevention and management of ovarian hyperstimulation syndrome. There is a theoretical possibility that targeting angiogenesis may improve the function of the polycystic ovary and a real role for targeting angiogenesis in ovarian cancer.

Correlation between IL-1β, IL-1Ra gene polymorphism and occurrence of polycystic ovary syndrome infertility

OBJECTIVE

To explore the relationship between IL-1β, IL-1Ra gene polymorphism and the occurrence of polycystic ovary syndrome (PCOS) infertility.

METHODS

A total of 59 PCOS infertility cases visiting the reproductive center of our hospital from Mar. 2010 to Mar. 2012 and 56 healthy women were selected. ELISA method was used for the detection of IL-1β, IL-1Ra levels, and the levels of serum supersensitivity C reaction protein (US-CRP), insulin (FINS), follicule-stimulating hormone (FSH) and fasting blood-glucose (FBG) were detected. PCR analysis technology was adopted to detect the gene polymorphism of the 511 site of IL-1β and the second introne of IL-1Ra.

RESULTS

The levels of IL-1β, IL-1Ra, US-CRP, FINS and FBG in blood serum of patients in PCOS group were significantly higher than those in control group (P<0.05 or P<0.01). The level of FSH in PCOS group was significantly lower than that in control group (P<0.05). The genotypic frequency of T/T, the 511 site of IL-1β in PCOS group was 42.37%, significantly higher than 12.50% in control group (P<0.01). The frequency of T allele was also significantly higher than that in control group (P<0.01). The genotypic frequency of I/V, the second introne of IL-1Ra in PCOS group was 20.34%, signiciantly higher than 3.57% in control group (P<0.05). The frequency of V allele in PCOS group was significantly higher than that in control group (P<0.05).

CONCLUSIONS

T allele of the 511 site of IL-1β gene and V allele of the second introne of IL-1Ra gene might be the genetic basis of the rising of IL-1β, IL-1Ra and US-CRP levels in blood serum of PCOS patients, and are associated with the infertility occurrence of PCOS patients.

Raman spectroscopy-based approach to detect aging-related oxidative damage in the mouse oocyte

PURPOSE

Detection of chemical modifications induced by aging-related oxidative damage in mouse metaphase II (MII) oocytes by Raman microspectroscopy.

METHODS

CD-1 mice at the age of 4-8 weeks (young mice) and 48-52 weeks (old mice), were superovulated and oocytes at metaphase II stage were recovered from oviducts. MII oocytes from young animals were divided into three groups: A) young oocytes, processed immediately after collection; B) in vitro aged oocytes, cultured in vitro for 10 h before processing; C) oxidative-stressed oocytes, exposed to 10 mM hydrogen peroxide for 2 min before processing. Oocytes from reproductively old mice were referred to as old oocytes (D). All the oocytes were analyzed by confocal Raman microspectroscopy. The spectra were statistically analyzed using Principal Component Analysis (PCA).

RESULTS

PCA evidenced that spectra from young oocytes (A) were clearly distinguishable from those obtained from in vitro-aged, oxidative-damaged and old oocytes (B, C, D) and presented significant differences in the bands attributable to lipid components (C = C stretching, 1,659 cm⁻¹; CH2 bending, 1,450 cm⁻¹; CH3 deformation,1,345 cm⁻¹; OH bending, C-N stretching, 1,211 cm⁻¹) and protein components (amide I band,1,659 cm⁻¹; CH2 bending modes and CH3 deformation, 1,450 cm⁻¹; C-N and C-C stretching vibrations, 1,132 cm⁻¹; phenylalanine's vibration, 1,035 cm⁻¹)

CONCLUSIONS

Raman spectroscopy is a valuable non-invasive tool for the identification of biochemical markers of oxidative damage and could represent a highly informative method of investigation to evaluate the oocyte quality.

Suboptimal nutrition in utero causes DNA damage and accelerated aging of the female reproductive tract

Early life exposure to adverse environments can lead to a variety of metabolic and cardiovascular diseases in offspring. We hypothesize that female reproductive function may also be affected, with subsequent implications for fertility. We used an established maternal low-protein model where animals are born small but undergo rapid postnatal catch-up growth by suckling a control-fed dam (recuperated offspring). Markers of oxidative stress and cellular aging in reproductive tract tissues were assessed at 3 and 6 mo of age. Recuperated offspring had lower birth weight than controls (P<0.01) but caught up during lactation. 4-Hydroxynonenal (4HNE; an indicator of oxidative stress) was increased in recuperated animals compared with controls in both ovaries and oviducts at 6 mo. At 3 and 6 mo, ovaries and oviducts of recuperated offspring had increased mitochondrial (mt)DNA copy number (P<0.01). By contrast, germ-line cells showed no difference in mtDNA copy number, suggesting they were protected from suboptimal maternal nutrition. Oviduct and somatic ovarian telomere length declined more rapidly with age in recuperated animals. This accelerated cellular aging was associated with a declined ovarian reserve in developmentally programmed animals. These findings have significant clinical implications in light of worldwide trends to delayed childbearing.

The aging ovary--the poor granulosa cells

The development of a competent oocyte intimately depends on the maintenance of energetic homeostasis in the ovarian and follicular microenvironment. On this basis, it is very likely that the oocyte ages as the ovary ages. Starting from the molecular evidence for energy perturbations in the whole ovary, we review current knowledge on the involvement of endogenous highly reactive metabolites in follicle aging. The first part provides an update of recent findings that confirm the key role of oxidative stress in aged granulosa cells. The second part focuses on studies providing evidence for the implication of advanced glycation end product (AGE) in aging reproductive dysfunction. With their prolonged half-life and ability to act as signaling molecules AGEs may gradually accumulate in the ovary and potentiate the wide spatiotemporal spread of oxidative stress. Clinical evidence for this view supports the hypothesis that AGE is a good candidate as a predictive marker and therapeutic target in new strategies for improving reproductive counseling in aging women.

Oxidative stress and the ageing endocrine system

Ageing is a process characterized by a progressive decline in cellular function, organismal fitness and increased risk of age-related diseases and death. Several hundred theories have attempted to explain this phenomenon. One of the most popular is the 'oxidative stress theory', originally termed the 'free radical theory'. The endocrine system seems to have a role in the modulation of oxidative stress; however, much less is known about the role that oxidative stress might have in the ageing of the endocrine system and the induction of age-related endocrine diseases. This Review outlines the interactions between hormones and oxidative metabolism and the potential effects of oxidative stress on ageing of endocrine organs. Many different mechanisms that link oxidative stress and ageing are discussed, all of which converge on the induction or regulation of inflammation. All these mechanisms, including cell senescence, mitochondrial dysfunction and microRNA dysregulation, as well as inflammation itself, could be targets of future studies aimed at clarifying the effects of oxidative stress on ageing of endocrine glands.

Oocytes isolated from dairy cows with reduced ovarian reserve have a high frequency of aneuploidy and alterations in the localization of progesterone receptor membrane component 1 and aurora kinase B

Oocytes isolated from cows of reproductive age with reduced antral follicle counts (AFC) have a diminished capacity of embryonic development, which may be related to alterations in the mechanism that directs the proper segregation of chromosomes. Because we demonstrated that progesterone receptor membrane component 1 (PGRMC1) is involved in chromosome congression and metaphase II (MII) plate formation, the present study was designed to determine 1) if the decrease in oocyte developmental competence observed in dairy cows with a reduced AFC is due to a higher incidence of aneuploidy and 2) whether alterations in PGRMC1 contributes to the incidence of aneuploidy. Oocytes from ovaries with reduced AFC and age-matched controls were matured in vitro and the occurrence of aneuploidy determined as well as the mRNA level and localization of PGRMC1. Although oocytes from ovaries with reduced AFC were capable of undergoing meiosis in vitro, these oocytes showed a 3-fold increase in aneuploidy compared to oocytes isolated from control ovaries (P < 0.05). Although Pgrmc1 mRNA levels were not altered, PGRMC1 and aurora kinase B (AURKB) failed to localize to precise focal points on MII chromosomes of oocytes from ovaries with reduced AFC. Furthermore, when oocytes of control ovaries were cultured with an inhibitor of AURKB activity, their MII plate was disrupted and PGRMC1 was not properly localized to the chromosomes. These results suggest that alterations in PGRMC1 and/or AURKB localization account in part for the increased aneuploidy and low development competence of oocytes from ovaries with reduced AFC.

Decreased Expression of Inhibitor of DNA-binding (Id) Proteins and Vascular Endothelial Growth Factor and Increased Apoptosis in Ovarian Aging

This study examined the expression of inhibitor of DNA-binding (Id) proteins and vascular endothelial growth factor (VEGF) in the ovary according to female age using a mice model as the first step in investigating the potential role of Ids and VEGF in ovarian aging. C57BL inbred female mice of three age groups (6-9, 14-16, and 23-26 weeks) were injected with 5 IU pregnant mare’s serum gonadotropin (PMSG) in order to synchronize the estrus cycle. After 48 h, ovarian expression of Ids and VEGF was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR), western blot and immunohistochemistry. Ovarian apoptosis was examined by ovarian expression of Bcl-2 and Bcl-xL. Expression of Id-1 and VEGF was decreased with advancing female age, but not Id-2, Id-3, and Id-4. In particular, their expressions were significantly decreased in aged mice of 23-26 weeks compared with the young mice of 6-9 weeks (p < 0.05). In contrast, ovarian apoptosis was greatly increased in the aged mice compared to the young mice. This result suggests that Id-1 may have an implicated role in ovarian aging by associating with VEGF.

Resveratrol protects against age-associated infertility in mice

STUDY QUESTION

Does resveratrol counteract age-associated infertility in a mouse model of reproductive aging?

SUMMARY ANSWER

Long-term-oral administration of resveratrol protects against the reduction of fertility with reproductive aging in mice.

WHAT IS KNOWN ALREADY

Loss of oocytes and follicles and reduced oocyte quality contribute to age-associated ovarian aging and infertility. Accumulation of free radicals with age leads to DNA mutations, protein damage, telomere shortening, apoptosis and accelerated ovarian aging. Increasing evidence shows that resveratrol, enriched in certain foods, for example red grapes and wine, has anti-tumor and anti-aging effects on somatic tissues by influencing various signaling pathways, including anti-oxidation, as well as activating Sirt1 and telomerase. We investigated the potential of resveratrol to stave off ovarian aging in the inbred C57/BL6 mouse model.

STUDY DESIGN, SIZE, DURATION

Young C57/BL6 females (aged 2-3 months) were fed with resveratrol added to drinking water at 30 mg/l (providing ∼7.0 mg/kg/day) for 6 or 12 months, and the fertility and ovarian functions were compared among mice treated with or without resveratrol, and young mice served as reproductive controls. Experiments were repeated three times, with an average of 25 females randomly allocated to each treatment group for each repeat.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Reproductive performance of female mice was determined by litter size, ovarian follicles and oocyte quantity and quality, and compared with age-matched controls. The impact of resveratrol on telomeres and telomerase activity, and expression of genes associated with cell senescence also was evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

Young mice fed with resveratrol for 12 months retained the capacity to reproduce, while age-matched controls produced no pups. Consistently, mice fed with resveratrol for 12 months exhibited a larger follicle pool than controls (P < 0.05). Furthermore, telomerase activity, telomere length and age-related gene expression in ovaries of mice fed with resveratrol resembled those of young mice, but differed (P < 0.05) from those of age-matched old mice. Resveratrol improved (P < 0.05) the number and quality of oocytes, as evidenced by spindle morphology and chromosome alignment. Also, resveratrol affected embryo development in vitro in a dose-dependent manner.

LIMITATIONS, REASONS FOR CAUTION

The doses of resveratrol and the experimental conditions used by different research groups have varied considerably, and the dosage influences both the effectiveness and toxicity of resveratrol. Fine-tuning the dosage of resveratrol likely will optimize its anti-aging effects on ovarian function.

WIDER IMPLICATIONS OF THE FINDINGS

Our data provide a proof of principle of the fertility-sparing effect of resveratrol in female mice. Although depletion of the ovarian reserve of high-quality oocytes also contributes to increased infertility with reproductive aging in women, the data obtained using a mouse model may not extrapolate directly to human reproduction, and more extensive research is needed if any clinic trials are to be attempted.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by MOST of China National Basic Research Program (grant number: 2010CB94500 and 2012CB911200). The authors have no competing interests to declare.

Improvement of ovarian response and oocyte quality of aged female by administration of bone morphogenetic protein-6 in a mouse model

BACKGROUND

Advancing female age remains a difficult problem in infertility treatment. Ovarian angiogenesis plays an important role in follicular development and the activation of ovarian angiogenesis has been emerged as a new strategy for the improvement of age-related decline of oocyte quality. BMP-6 affect gonadotropin signals in granulosa cells and it promotes normal fertility by enabling appropriate response to LH and normal oocyte quality. BMP-6 has a potential role in regulation of angiogenesis and regulates the expression of inhibitor of DNA-binding proteins (Ids). Ids involved in the control and timing of follicle selection and granulosa cells differentiation. Especially, Id-1 is well-characterized target of BMP-6 signaling. Therefore, this study investigated whether co-administration of BMP-6 during superovulation process improves ovarian response, oocyte quality and expression of Id-1 and vascular endothelial growth factor (VEGF) in the ovary of aged female using a mouse model.

METHODS

Aged C57BL/6 female mice (26-31 weeks old) were superovulated by injection with 0.1 mL of 5 IU equine chorionic gonadotropin (eCG) containing recombinant mouse BMP-6 at various doses (0, 0.01, 0.1, 1, and 10 ng), followed by injection with 5 IU human chorionic gonadotropin (hCG) 48 h later. Then, the mice were immediately paired with an individual male. The aged control group was superovulated without BMP-6. Young mice of 6-9 weeks old were superovulated without BMP-6 as a positive control for superovulation and in vitro culture of embryos. Eighteen hours after hCG injection, zygotes were retrieved and cultured for 4 days. Both ovaries of each mouse were provided in the examination of ovarian expression of Id-1 and VEGF by reverse transcriptase-polymerase chain reaction, western blot, and immunohistochemistry.

RESULTS

Administration of 0.1 ng BMP-6 significantly increased the number and blastocyst formation rate of oocytes ovulated and ovarian expression of Id-1 and VEGF compared to aged control mice. These increased levels were comparable to those of young control mice.

CONCLUSIONS

This result suggests that BMP-6 during ovulation induction plays an important role in improvement of oocyte quality and ovarian response of aged female, possibly by regulating of ovarian Id-1 and VEGF expression.

Mono-(2-ethylhexyl) phthalate induces oxidative stress and inhibits growth of mouse ovarian antral follicles

Mono-(2-ethylhexyl) phthalate (MEHP) is the active metabolite of the most commonly used plasticizer, di-(2-ethylhexyl) phthalate, and is considered to be a reproductive toxicant. However, little is known about the effects of MEHP on ovarian antral follicles. Thus, the present study tested the hypothesis that MEHP inhibits follicle growth via oxidative stress pathways. The data indicate that MEHP increases reactive oxygen species (ROS) levels and inhibits follicle growth in antral follicles, whereas N-acetylcysteine (NAC; an antioxidant) restores ROS levels to control levels and rescues follicles from MEHP-induced inhibition of follicle growth. To further analyze the mechanism by which MEHP induces oxidative stress and inhibits follicle growth, the expression and activities of various key antioxidant enzymes (copper/zinc superoxide dismutase [SOD1], glutathione peroxidase [GPX], and catalase [CAT]) and the expression of key cell-cycle regulators (Ccnd2, Ccne1, and Cdk4) and apoptotic regulators (Bcl-2 and Bax) were compared in control and MEHP-treated follicles. The data indicate that MEHP inhibits the expression and activities of SOD1 and GPX; does not inhibit Cat expression; inhibits the expression of Ccnd2, Ccne1, Cdk4, and Bcl-2; but increases the expression of Bax compared to controls. Furthermore, NAC blocks these toxic effects of MEHP. Collectively, these data suggest that MEHP induces oxidative stress by disrupting the activities of antioxidant enzymes. This may lead to decreased expression of cell-cycle regulators and antiapoptotic regulators and increased expression of proapoptotic factors, which then may lead to inhibition of follicle growth.

Late-onset running biphasically improves redox balance, energy- and methylglyoxal-related status, as well as SIRT1 expression in mouse hippocampus

Despite the active research in this field, molecular mechanisms underlying exercise-induced beneficial effects on brain physiology and functions are still matter of debate, especially with regard to biological processes activated by regular exercise affecting the onset and progression of hippocampal aging in individuals unfamiliar with habitual physical activity. Since such responses seem to be mediated by changes in antioxidative, antiglycative and metabolic status, a possible exercise-induced coordinated response involving redox, methylglyoxal- and sirtuin-related molecular networks may be hypothesized. In this study, hippocampi of CD1 mice undergoing the transition from mature to middle age were analyzed for redox-related profile, oxidative and methylglyoxal-dependent damage patterns, energy metabolism, sirtuin1 and glyoxalase1 expression after a 2- or 4-mo treadmill running program. Our findings suggested that the 4-mo regular running lowered the chance of dicarbonyl and oxidative stress, activated mitochondrial catabolism and preserved sirtuin1-related neuroprotection. Surprisingly, the same cellular pathways were negatively affected by the first 2 months of exercise, thus showing an interesting biphasic response. In conclusion, the duration of exercise caused a profound shift in the response to regular running within the rodent hippocampus in a time-dependent fashion. This research revealed important details of the interaction between exercise and mammal hippocampus during the transition from mature to middle age, and this might help to develop non-pharmacological approaches aimed at retarding brain senescence, even in individuals unfamiliar with habitual exercise.

A novel loss-of-function mutation in Npr2 clarifies primary role in female reproduction and reveals a potential therapy for acromesomelic dysplasia, Maroteaux type

We discovered a new spontaneous mutant allele of Npr2 named peewee (pwe) that exhibits severe disproportionate dwarfism and female infertility. The pwe phenotype is caused by a four base-pair deletion in exon 3 that generates a premature stop codon at codon 313 (L313X). The Npr2(pwe/pwe) mouse is a model for the human skeletal dysplasia acromesomelic dysplasia, Maroteaux type (AMDM). We conducted a thorough analysis of the female reproductive tract and report that the primary cause of Npr2(pwe/pwe) female infertility is premature oocyte meiotic resumption, while the pituitary and uterus appear to be normal. Npr2 is expressed in chondrocytes and osteoblasts. We determined that the loss of Npr2 causes a reduction in the hypertrophic and proliferative zones of the growth plate, but mineralization of skeletal elements is normal. Mutant tibiae have increased levels of the activated form of ERK1/2, consistent with the idea that natriuretic peptide receptor type 2 (NPR2) signaling inhibits the activation of the MEK/ERK mitogen activated protein kinase pathway. Treatment of fetal tibiae explants with mitogen activated protein kinase 1 and 2 inhibitors U0126 and PD325901 rescues the Npr2(pwe/pwe) growth defect, providing a promising foundation for skeletal dysplasia therapeutics.

Steroid concentrations and immunoexpression of steroidogenic enzymes in ovaries of aged bank voles: effect of photoperiod

The main objective of the present study was to establish morphological and steroidogenic changes occurring in the ovaries of senescent bank voles, with respect to the photoperiod of rearing. Obtained results revealed less pronounced changes in the ovaries of females reared in a long photoperiod (LD). Their gonads still possessed some healthy follicles and old corpora lutea (CLs). Senescence-related changes encompassed the presence of abnormal follicles, large regions containing extra-follicular luteinized granulosa cells and numerous clusters of hypertrophied theca/interstitial cells, exhibiting strong expression of 3β-hydroxysteroid dehydrogenase (3β-HSD) and much weaker that of cytochrome P450c17. More pronounced changes were observed in animals reared in short day (SD) conditions and included the presence of only few, usually abnormal follicles and/or remnants of CLs in the surface region, and the isle-like clusters of cells in the ovarian medulla. The clusters were composed of cells generally featuring strong 3β-HSD and/or P450c17 immunoreaction. Steroid content analysis revealed that progesterone dominated in the ovaries of LD bank voles and androgens in SD animals, while estradiol content was very low in both investigated groups. These studies showed for the first time morphological and steroidogenic changes found in the ovaries of senescent bank voles and indicated an important role of length light conditions in the process of reproductive aging.

Current understanding of ovarian aging

The reproductive system of human female exhibits a much faster rate of aging than other body systems. Ovarian aging is thought to be dominated by a gradual decreasing numbers of follicles, coinciding with diminished quality of oocytes. Menopause is the final step in the process of ovarian aging. This review focuses on the mechanisms underlying the ovarian aging involving a poor complement of follicles at birth and a high rate of attrition each month, as well as the alternated endocrine factors. We also discuss the possible causative factors that contribute to ovarian aging, e.g., genetic factors, accumulation of irreparable damage of microenvironment, pathological effect and other factors. The appropriate and reliable methods to assess ovarian aging, such as quantification of follicles, endocrine measurement and genetic testing have also been discussed. Increased knowledge of the ovarian aging mechanisms may improve the prevention of premature ovarian failure.

Women with reduced ovarian reserve or advanced maternal age have an altered follicular environment

OBJECTIVE

To determine whether altered follicular environment is associated with ovarian reserve or maternal age.

DESIGN

Prospective study examining follicular fluid (FF) composition and follicular cell metabolism.

SETTING

University research department and private IVF clinic.

PATIENT(S)

Women (n = 54) undergoing routine IVF treatment were allocated to one of three groups based on ovarian reserve and maternal age.

INTERVENTION(S)

Surplus FF, granulosa cells (GC), and cumulus cells (CC) were collected.

MAIN OUTCOME MEASURE(S)

Follicular fluid concentrations of carbohydrates, hormones, and selected ions. Metabolic analysis and gene expression of GCs and CCs.

RESULT(S)

Compared to women <35 years with normal ovarian reserve, FF glucose levels were significantly decreased and lactate and progesterone (P4) concentrations significantly increased in women with reduced ovarian reserve or advanced maternal age, whereas GC and CC glucose uptake, lactate production, and phosphofructokinase platelet gene expression were significantly increased. Granulosa cell P4 production from women with reduced ovarian reserve or advanced maternal age was decreased; however, in CCs the reverse was observed with increased gene expression in P4 receptor, prostaglandin E receptor-2, cytosolic phospholipase A2, and tumor protein 53.

CONCLUSION(S)

Women with either reduced ovarian reserve or advanced maternal age have altered follicular cell metabolism, FF metabolites, and P4 production. This perturbed environment may be responsible for impaired oocyte developmental competence and subsequent embryo development.

Protein modification as oxidative stress marker in normal and pathological human seminal plasma

OBJECTIVE

Our study aims to assess the oxidative stress status of seminal plasma from normozoospermic, azoospermic, and leukocytospermic males, since abnormal sperm and leukocytes in human ejaculates are the main source of reactive oxygen species (ROS) which lead to oxidative damages. For this purpose we applied a biochemical approach to the assessment of the oxidative stress status by using two-dimensional (2D) electrophoresis to check the level of protein oxidation after specific labeling of free thiol (-SH) groups.

METHODS

Seminal plasma samples from normal and pathological males were analyzed by a luminol-based chemiluminescent assay. The same samples after specific labeling of free -SH groups with 3-N-maleimidopropionyl biocytin, were analyzed by 2D electrophoresis and computer-assisted semiquantitative determination of the amount of free -SH groups.

RESULTS

Using a standard chemiluminescence assay, we demonstrated a high, low and normal level of ROS, respectively, in seminal plasma from leukocytospermic, azoospermic, and normozoospermic subjects. By 2D electrophoresis and streptavidin blotting of specifically labeled free -SH groups of proteins, we detected in the same samples a higher level of oxidated -SH groups comparable between azoospermic and leukocytospermic samples, whereas a significantly higher level of free -SH groups was detected in normozoospermic subjects.

DISCUSSION

Our results demonstrated that a pathological oxidative stress status in seminal plasma may be revealed by the levels of the protein free -SH groups, both in the presence or absence of cells.

Sphingosine-1-phosphate inhibits H2O2-induced granulosa cell apoptosis via the PI3K/Akt signaling pathway

OBJECTIVE

To investigate the protective effect of sphingosine-1-phosphate (S1P) against H(2)O(2)-induced apoptosis in human granulosa cell cultures with freshly harvested granulosa cells.

DESIGN

Experimental study.

SETTING

Academic medical center for reproductive medicine.

PATIENT(S)

Cultures of primary granulosa cells isolated from women undergoing in vitro fertilization (IVF).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Cell apoptosis and Western blot analysis of signaling pathway proteins.

RESULT(S)

We found that S1P (1 and 10 mM) statistically significantly decreased granulosa cell apoptosis after H(2)O(2) treatment. The decreased cell apoptosis induced by S1P was abolished after treatment with VPC23019, an inhibitor of S1P1 and S1P3 receptors, W146, an inhibitor of S1P1 receptors, and CAY10444, an inhibitor of S1P3 receptors. A Western blot analysis revealed that the level of phospho-Akt increased and peaked at 10 minutes after 10 mM S1P exposure.

CONCLUSION(S)

Treatment with S1P can inhibit the apoptosis of granulosa cells in response to oxidative stress induced by H(2)O(2). The protective effect of S1P is mediated by activating the PI3K/Akt pathway, and the antiapoptotic effect of S1P is mainly mediated through the S1P1 and S1P3 receptor.

Healthy aging - insights from Drosophila

Human life expectancy has nearly doubled in the past century due, in part, to social and economic development, and a wide range of new medical technologies and treatments. As the number of elderly increase it becomes of vital importance to understand what factors contribute to healthy aging. Human longevity is a complex process that is affected by both environmental and genetic factors and interactions between them. Unfortunately, it is currently difficult to identify the role of genetic components in human longevity. In contrast, model organisms such as C. elegans, Drosophila, and rodents have facilitated the search for specific genes that affect lifespan. Experimental evidence obtained from studies in model organisms suggests that mutations in a single gene may increase longevity and delay the onset of age-related symptoms including motor impairments, sexual and reproductive and immune dysfunction, cardiovascular disease, and cognitive decline. Furthermore, the high degree of conservation between diverse species in the genes and pathways that regulate longevity suggests that work in model organisms can both expand our theoretical knowledge of aging and perhaps provide new therapeutic targets for the treatment of age-related disorders.

Delay in oocyte aging in mice by the antioxidant N-acetyl-L-cysteine (NAC)

BACKGROUND

Ovarian aging is associated with declining numbers and quality of oocytes and follicles. Oxidative stress by reactive oxygen species (ROS) contributes to somatic aging in general, and also has been implicated in reproductive aging. Telomere shortening is also involved in aging, and telomeres are particularly susceptible to ROS-induced damage. Previously, we have shown that antioxidant N-acetyl-L-cysteine (NAC) effectively rescues oocytes and embryos from ROS-induced telomere shortening and apoptosis in vitro. Using mice as models, we tested the hypothesis that reducing oxidative stress by NAC might prevent or delay ovarian aging in vivo.

METHODS

Initially, young females were treated with NAC in drinking water for 2 months and the quality of fertilized oocytes and early embryo development were evaluated. Next, young mice 1-1½ months old were treated for 1 year with NAC added in drinking water, and their fertility was analyzed starting at 6 months, as indicated by litter size, oocyte number and quality. The ovaries were also examined for telomere activity and length and the expression of selected genes related to aging and DNA damage.

RESULTS

Short-term treatment of mice for 2 months with NAC demonstrated that NAC improved the quality of fertilized oocytes and early embryo development. Mice treated with a long-term low concentration (0.1 mM) of NAC had increased litter sizes at the ages of 7-10 months compared with age-matched controls without NAC treatment. NAC also increased the quality of the oocytes from these older mice. Moreover, the expression of sirtuins was increased, telomerase activity was higher and telomere length was longer in the ovaries of mice treated with NAC compared with those of the control group.

CONCLUSIONS

These data suggest that appropriate treatment with the antioxidant NAC postpones the process of oocyte aging in mice.

Long term running biphasically improves methylglyoxal-related metabolism, redox homeostasis and neurotrophic support within adult mouse brain cortex

Oxidative stress and neurotrophic support decline seem to be crucially involved in brain aging. Emerging evidences indicate the pro-oxidant methylglyoxal (MG) as a key player in the age-related dicarbonyl stress and molecular damage within the central nervous system. Although exercise promotes the overproduction of reactive oxygen species, habitual exercise may retard cellular aging and reduce the age-dependent cognitive decline through hormetic adaptations, yet molecular mechanisms underlying beneficial effects of exercise are still largely unclear. In particular, whereas adaptive responses induced by exercise initiated in youth have been broadly investigated, the effects of chronic and moderate exercise begun in adult age on biochemical hallmarks of very early senescence in mammal brains have not been extensively studied. This research investigated whether a long-term, forced and moderate running initiated in adult age may affect the interplay between the redox-related profile and the oxidative-/MG-dependent molecular damage patterns in CD1 female mice cortices; as well, we investigated possible exercise-induced effects on the activity of the brain derived neurotrophic factor (BDNF)-dependent pathway. Our findings suggested that after a transient imbalance in almost all parameters investigated, the lately-initiated exercise regimen strongly reduced molecular damage profiles in brains of adult mice, by enhancing activities of the main ROS- and MG-targeting scavenging systems, as well as by preserving the BDNF-dependent signaling through the transition from adult to middle age.

Release of superoxide dismutase-1 by day 3 embryos of varying quality and implantation potential

PURPOSE

To determine if the antioxidant superoxide dismutase-1 (SOD1 or Cu,Zn-SOD) is released by cultured human cleavage-stage embryos and to assess any link between SOD1 and implantation potential.

METHODS

Women (n = 91; ≤40 years old) undergoing IVF treatment with transfer of one or two 8-cell embryos that resulted in 0 or 100% implantation were included. Following individual embryo culture, spent medium samples (n = 122) were collected and levels of SOD1 protein were measured by an enzyme-linked immunosorbent assay. SOD1 detection and concentration in embryo spent medium were analyzed in relation to embryo fragmentation and symmetry scores, and implantation (viable fetus at >12 weeks).

RESULTS

Cleavage-stage embryos release SOD1 protein into the spent culture medium. Neither detection nor concentration of SOD1 was related to implantation. There was a positive relationship between increased embryo fragmentation scores and SOD1 release, with no apparent association with symmetry. In non-pregnant cycles, the release of SOD1 decreased with increasing maternal age.

CONCLUSIONS

While SOD1 does not predict implantation potential of select good-quality embryos, our data support the need to evaluate the biological significance of released SOD1 by embryos of varying quality and from patients of varying age.

Protein profile changes during porcine oocyte aging and effects of caffeine on protein expression patterns

It has been shown that oocyte aging critically affects reproduction and development. By using proteomic tools, in the present study, changes in protein profiles during porcine oocyte aging and effects of caffeine on oocyte aging were investigated. By comparing control MII oocytes with aging MII oocytes, we identified 23 proteins that were up-regulated and 3 proteins that were down-regulated during the aging process. In caffeine-treated oocytes, 6 proteins were identified as up-regulated and 12 proteins were identified as down-regulated. A total of 38 differentially expressed proteins grouped into 5 regulation patterns were determined to relate to the aging and anti-aging process. By using the Gene Ontology system, we found that numerous functional gene products involved in metabolism, stress response, reactive oxygen species and cell cycle regulation were differentially expressed during the oocyte aging process, and most of these proteins are for the first time reported in our study, including 2 novel proteins. In addition, several proteins were found to be modified during oocyte aging. These data contribute new information that may be useful for future research on cellular aging and for improvement of oocyte quality.

Di (2-ethylhexyl) phthalate inhibits growth of mouse ovarian antral follicles through an oxidative stress pathway

Di (2-ethylhexyl) phthalate (DEHP) is a plasticizer that has been shown to inhibit growth of mouse antral follicles, however, little is known about the mechanisms by which DEHP does so. Oxidative stress has been linked to follicle growth inhibition as well as phthalate-induced toxicity in non-ovarian tissues. Thus, we hypothesized that DEHP causes oxidative stress and that this leads to inhibition of the growth of antral follicles. To test this hypothesis, antral follicles isolated from CD-1 mice (age 31-35days) were cultured with vehicle control (dimethylsulfoxide [DMSO]) or DEHP (1-100μg/ml)±N-acetyl cysteine (NAC, an antioxidant at 0.25-1mM). During culture, follicles were measured daily. At the end of culture, follicles were collected and processed for in vitro reactive oxygen species (ROS) assays to measure the presence of free radicals or for measurement of the expression and activity of various key antioxidant enzymes: Cu/Zn superoxide dismutase (SOD1), glutathione peroxidase (GPX) and catalase (CAT). The results indicate that DEHP inhibits the growth of follicles compared to DMSO control and that NAC (0.25-1mM) blocks the ability of DEHP to inhibit follicle growth. Furthermore, DEHP (10μg/ml) significantly increases ROS levels and reduces the expression and activity of SOD1 compared to DMSO controls, whereas NAC (0.5mM) rescues the effects of DEHP on ROS levels and SOD1. However, the expression and activity of GPX and CAT were not affected by DEHP treatment. Collectively, these data suggest that DEHP inhibits follicle growth by inducing production of ROS and by decreasing the expression and activity of SOD1.

Age-related accumulation of non-heme ferric and ferrous iron in mouse ovarian stroma visualized by sensitive non-heme iron histochemistry

Sensitive non-heme iron histochemistry--namely, the perfusion-Perls method and perfusion-Turnbull method--was applied to study the distribution and age-related accumulation of non-heme ferric iron and ferrous iron in mouse ovary. Light and electron microscopic studies revealed that non-heme ferric iron is distributed predominantly in stromal tissue, especially in macrophages. By contrast, the distribution of non-heme ferrous iron was restricted to a few ovoid macrophages. Aged ovaries exhibited remarkable non-heme iron accumulation in all stromal cells. In particular, non-heme ferrous iron level was increased in stromal tissue, suggestive of increased levels of redox-active iron, which can promote oxidative stress. Moreover, intense localization of both non-heme ferric and ferrous iron was observed in aggregated large stromal cells that were then characterized as ceroid-laden enlarged macrophages with frothy cytoplasm. Intraperitoneal iron overload in adult mice resulted in non-heme iron deposition in the entire stroma and generation of enlarged macrophages, suggesting that excessive iron accumulation induced macrophage morphological changes. The data indicated that non-heme iron accumulation in ovarian stromal tissue may be related to aging of the ovary due to increasing oxidative stress.

TAp73 is downregulated in oocytes from women of advanced reproductive age

Studies on oocyte transcriptome are important to understand the biological pathways involved in oogenesis, totipotence and early embryonic development. Moreover, genes regulating physiological pathways in gametes could represent potential candidates for reproductive disorders. In addition to oocyte specific transcription factors, also the members of the p53 family could be etiologically involved due to their biological functions. In fact, their role in the control of cell cycle, apoptosis, and germ-line genome stability is well known. Female reproductive aging is one of the causes of fertility reduction and it is often associated with egg aneuploidy increase. In order to verify the potential involvement of p73 in reproductive aging, we determined its expression in single mature MII oocytes from two groups of women, younger than 35 or older than 38 years, respectively. We found that TAp73 isoforms are down regulated in oocytes from women older than 38 years. We confirmed these data in pools of mouse oocytes. TAp73 down regulation in oocytes from women of advanced reproductive age could explain both the reduction of fertility and the increase of newborns with chromosomal abnormalities.

Expression of SDF-1α and leptin, and their effect on expression of angiogenic factors in mouse ovaries

OBJECTIVE

Ovarian angiogenesis plays an important role in folliculogenesis. However, little is known about the expression of angiogenic factors during follicular development according to female age. Stromal cell derived factor-1α (SDF-1α) plays a role in granulosa cell survival and embryo quality as an angiogenic chemokine. Leptin is also involved in folliculogenesis and angiogenesis. This study examined expression of SDF-1α and leptin, and their effects on the expression of angiogenic factors in the ovary during follicular development according to female age.

METHODS

Ovaries were collected from C57BL mice of two age groups (6-9 weeks and 24-26 weeks) at 6, 12, 24, and 48 hours after 5 IU pregnant mare's serum gonadotropin (PMSG) injection. The expression of ovarian SDF-1α and leptin mRNA was evaluated by RT-PCR. In the organ culture experiment, the ovaries were cultured in transwell permeable supports with Waymouth's medium treated with various doses of SDF-1α (50-200 ng/mL) or leptin (0.01-1 µg/mL) for 7 days. Then, mRNA expression of vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), and visfatin were examined in the cultured ovaries.

RESULTS

Expression of SDF-1α and leptin in the ovary was significantly lower in the aged mouse group compared to the young mouse group (p<0.05). Expression of these two factors increased with follicular development after PMSG administration. SDF-1α treatment stimulated visfatin expression in a dose-dependent manner, while leptin treatment significantly increased eNOS expression.

CONCLUSION

These results suggest that decrease of ovarian SDF-1α and leptin expression may be associated with aging-related reduction of ovarian function. SDF-1α and leptin may play a role in follicular development by regulating the expression of angiogenic factors in mouse ovaries.