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Per- and poly-fluoroalkyl substances (PFAS) and female reproductive outcomes: PFAS elimination, endocrine-mediated effects, and disease.
Rickard, BP, Rizvi, I, Fenton, SE
Toxicology. 2022;:153031
Abstract
Per- and poly-fluoroalkyl substances (PFAS) are widespread environmental contaminants frequently detected in drinking water supplies worldwide that have been linked to a variety of adverse reproductive health outcomes in women. Compared to men, reproductive health effects in women are generally understudied while global trends in female reproduction rates are declining. Many factors may contribute to the observed decline in female reproduction, one of which is environmental contaminant exposure. PFAS have been used in home, food storage, personal care and industrial products for decades. Despite the phase-out of some legacy PFAS due to their environmental persistence and adverse health effects, alternative, short-chain and legacy PFAS mixtures will continue to pollute water and air and adversely influence women's health. Studies have shown that both long- and short-chain PFAS disrupt normal reproductive function in women through altering hormone secretion, menstrual cyclicity, and fertility. Here, we summarize the role of a variety of PFAS and PFAS mixtures in female reproductive tract dysfunction and disease. Since these chemicals may affect reproductive tissues directly or indirectly through endocrine disruption, the role of PFAS in breast, thyroid, and hypothalamic-pituitary-gonadal axis function are also discussed as the interplay between these tissues may be critical in understanding the long-term reproductive health effects of PFAS in women. A major research gap is the need for mechanism of action data - the targets for PFAS in the female reproductive and endocrine systems are not evident, but the effects are many. Given the global decline in female fecundity and the ability of PFAS to negatively impact female reproductive health, further studies are needed to examine effects on endocrine target tissues involved in the onset of reproductive disorders of women.
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Iron status in athletic females, a shift in perspective on an old paradigm.
Badenhorst, CE, Goto, K, O'Brien, WJ, Sims, S
Journal of sports sciences. 2021;(14):1565-1575
Abstract
Iron deficiency is a common nutrient deficiency within athletes, with sport scientists and medical professionals recognizing that athletes require regular monitoring of their iron status during intense training periods. Revised considerations for athlete iron screening and monitoring have suggested that males get screened biannually during heavy training periods and females require screening biannually or quarterly, depending on their previous history of iron deficiency. The prevalence of iron deficiency in female athletes is higher than their male counterparts and is often cited as being a result of the presence of a menstrual cycle in the premenopausal years. This review has sought to revise our current understanding of female physiology and the interaction between primary reproductive hormones (oestrogen and progesterone) and iron homoeostasis in females. The review highlights an apparent symbiotic relationship between iron metabolism and the menstrual cycle that requires additional research as well as identifying areas of the menstrual cycle that may be primed for nutritional iron supplementation.
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Methodological Approach of the Iron and Muscular Damage: Female Metabolism and Menstrual Cycle during Exercise Project (IronFEMME Study).
Peinado, AB, Alfaro-Magallanes, VM, Romero-Parra, N, Barba-Moreno, L, Rael, B, Maestre-Cascales, C, Rojo-Tirado, MA, Castro, EA, Benito, PJ, Ortega-Santos, CP, et al
International journal of environmental research and public health. 2021;(2)
Abstract
Background: The increase in exercise levels in the last few years among professional and recreational female athletes has led to an increased scientific interest about sports health and performance in the female athlete population. The purpose of the IronFEMME Study described in this protocol article is to determine the influence of different hormonal profiles on iron metabolism in response to endurance exercise, and the main markers of muscle damage in response to resistance exercise; both in eumenorrheic, oral contraceptive (OC) users and postmenopausal well-trained women. Methods: This project is an observational controlled randomized counterbalanced study. One hundered and four (104) active and healthy women were selected to participate in the IronFEMME Study, 57 of which were eumenorrheic, 31 OC users and 16 postmenopausal. The project consisted of two sections carried out at the same time: iron metabolism (study I) and muscle damage (study II). For the study I, the exercise protocol consisted of an interval running test (eight bouts of 3 min at 85% of the maximal aerobic speed), whereas the study II protocol was an eccentric-based resistance exercise protocol (10 sets of 10 repetitions of plate-loaded barbell parallel back squats at 60% of their one repetition maximum (1RM) with 2 min of recovery between sets). In both studies, eumenorrheic participants were evaluated at three specific moments of the menstrual cycle: early-follicular phase, late-follicular phase and mid-luteal phase; OC users performed the trial at two moments: withdrawal phase and active pill phase. Lastly, postmenopausal women were only tested once, since their hormonal status does not fluctuate. The three-step method was used to verify the menstrual cycle phase: calendar counting, blood test confirmation, and urine-based ovulation kits. Blood samples were obtained to measure sex hormones, iron metabolism parameters, and muscle damage related markers. Discussion: IronFEMME Study has been designed to increase the knowledge regarding the influence of sex hormones on some aspects of the exercise-related female physiology. Iron metabolism and exercise-induced muscle damage will be studied considering the different reproductive status present throughout well-trained females' lifespan.
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The effect of the menstrual cycle and hyperglycaemia on hormonal and metabolic responses during exercise.
Hulton, AT, Malone, JJ, Campbell, IT, MacLaren, DPM
European journal of applied physiology. 2021;(11):2993-3003
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Abstract
PURPOSE Variations in substrate metabolism have been identified in women during continuous steady-state aerobic exercise performed at the same relative intensity throughout discrete phases of the menstrual cycle, although some evidence exists that this is abolished when carbohydrate is ingested. This investigation examined the effects of a supraphysiologic exogenous glucose infusion protocol, administered during two phases of the menstrual cycle (follicular and luteal) in eumenorrheic women to identify differences between metabolic, hormonal and substrate oxidative responses. METHODS During the experimental conditions, blood glucose was infused intravenously at rates to "clamp" blood glucose at 10 mM in seven healthy females (age 20 ± 1 y, mass 55.0 ± 4.1 kg, [Formula: see text] 40.0 ± 1.8 ml/kg/min). Following 30 min of seated rest, participants exercised on a cycle ergometer for 90 min at 60% [Formula: see text]. During the rest period and throughout exercise, blood metabolites and hormones were collected at regular intervals, in addition to expired air for the measurement of substrate oxidation. RESULTS Significant differences between ovarian hormones and menstrual phase were identified, with estrogen significantly higher during the luteal phase compared to the follicular phase (213.28 ± 30.70 pmol/l vs 103.86 ± 13.85 pmol/l; p = 0.016), and for progesterone (14.23 ± 4.88 vs 2.11 ± 0.36 nmol/l; p = 0.042). However, no further significance was identified in any of the hormonal, metabolite or substrate utilisation patterns between phases. CONCLUSION These data demonstrate that the infusion of a supraphysiological glucose dose curtails any likely metabolic influence employed by the fluctuation of ovarian hormones in eumenorrheic women during moderate exercise.
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One-carbon metabolism during the menstrual cycle and pregnancy.
Kim, R, Nijhout, HF, Reed, MC
PLoS computational biology. 2021;(12):e1009708
Abstract
Many enzymes in one-carbon metabolism (OCM) are up- or down-regulated by the sex hormones which vary diurnally and throughout the menstrual cycle. During pregnancy, estradiol and progesterone levels increase tremendously to modulate physiological changes in the reproductive system. In this work, we extend and improve an existing mathematical model of hepatic OCM to understand the dynamic metabolic changes that happen during the menstrual cycle and pregnancy due to estradiol variation. In particular, we add the polyamine drain on S-adenosyl methionine and the direct effects of estradiol on the enzymes cystathionine β-synthase (CBS), thymidylate synthase (TS), and dihydrofolate reductase (DHFR). We show that the homocysteine concentration varies inversely with estradiol concentration, discuss the fluctuations in 14 other one-carbon metabolites and velocities throughout the menstrual cycle, and draw comparisons with the literature. We then use the model to study the effects of vitamin B12, vitamin B6, and folate deficiencies and explain why homocysteine is not a good biomarker for vitamin deficiencies. Additionally, we compute homocysteine throughout pregnancy, and compare the results with experimental data. Our mathematical model explains how numerous homeostatic mechanisms in OCM function and provides new insights into how homocysteine and its deleterious effects are influenced by estradiol. The mathematical model can be used by others for further in silico experiments on changes in one-carbon metabolism during the menstrual cycle and pregnancy.
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Effect of resveratrol on menstrual cyclicity, hyperandrogenism and metabolic profile in women with PCOS.
Mansour, A, Samadi, M, Sanginabadi, M, Gerami, H, Karimi, S, Hosseini, S, Shirzad, N, Hekmatdoost, A, Mahdavi-Gorabi, A, Mohajeri-Tehrani, MR, et al
Clinical nutrition (Edinburgh, Scotland). 2021;(6):4106-4112
Abstract
AIM: The aim of this randomized trial was to find whether resveratrol could improve menstrual dysfunction, clinical signs (i.e., acne and hair loss), and the biochemical evidence of hyperandrogenism in the women with PCOS. METHODS Women, in the age range of 18-40 years, diagnosed with PCOS, as defined by the Rotterdam criteria, and no other known cause of abnormal menstruation, were recruited. Participants were randomized based on a 1:1 ratio, to either 1000 mg resveratrol or 1000 mg placebo daily groups, for a period of 3 months. RESULTS Seventy-eight patients were randomized: 39 to the resveratrol group and 39 to placebo. Results were analyzed according to the intention-to-treat principle. At the end of study, it was found that women who received resveratrol had a statistically higher regular menstruation rate, as compared to those who got placebo (76.47% vs. 51.61%; p = 0.03), and lower hair loss (32.10% vs. 68.00%; p = 0.009). We also found no significant differences between the two groups in terms of ovarian and adrenal androgens, sex hormone binding globulin (SHBG) levels, free androgen index (FAI), glycoinsulinemic metabolism and lipid profile. Moreover, the resveratrol treatment did not interfere with the thyroid, liver and kidney functions. The negative effect of resveratrol on the body composition was also observed, though not influencing changes in the weight, relative to the placebo group. CONCLUSION Resveratrol improved menstrual cyclicity and hair loss, even though levels of androgens, insulin and lipids remained unchanged.
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Bidirectional Interactions between the Menstrual Cycle, Exercise Training, and Macronutrient Intake in Women: A Review.
Rocha-Rodrigues, S, Sousa, M, Lourenço Reis, P, Leão, C, Cardoso-Marinho, B, Massada, M, Afonso, J
Nutrients. 2021;(2)
Abstract
Women have a number of specificities that differentiate them from men. In particular, the role of sex steroid hormones and the menstrual cycle (MC) significantly impact women's physiology. The literature has shown nonlinear relationships between MC, exercise, and nutritional intake. Notably, these relationships are bidirectional and less straightforward than one would suppose. For example, the theoretical implications of the MC's phases on exercise performance do not always translate into relevant practical effects. There is often a disconnect between internal measures (e.g., levels of hormone concentrations) and external performance. Furthermore, it is not entirely clear how nutritional intake varies across the MC's phases and whether these variations impact on exercise performance. Therefore, a thorough review of the existing knowledge could help in framing these complex relationships and potentially contribute to the optimization of exercise prescription and nutritional intake according to the naturally occurring phases of the MC. Throughout this review, an emerging trend is the lack of generalizability and the need to individualize interventions, since the consequences of the MC's phases and their relationships with exercise and nutritional intake seem to vary greatly from person to person. In this sense, average data are probably not relevant and could potentially be misleading.
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A new hypothesis linking oxytocin to menstrual migraine.
Bharadwaj, VN, Porreca, F, Cowan, RP, Kori, S, Silberstein, SD, Yeomans, DC
Headache. 2021;(7):1051-1059
Abstract
OBJECTIVE To highlight the emerging understanding of oxytocin (OT) and oxytocin receptors (OTRs) in modulating menstrual-related migraine (MRM). BACKGROUND MRM is highly debilitating and less responsive to therapy, and attacks are of longer duration than nonmenstrually related migraine. A clear understanding of the mechanisms underlying MRM is lacking. METHODS We present a narrative literature review on the developing understanding of the role of OT and the OTR in MRM. Literature on MRM on PubMed/MEDLINE database including clinical trials and basic science publications was reviewed using specific keywords. RESULTS OT is a cyclically released hypothalamic hormone/neurotransmitter that binds to the OTR resulting in inhibition of trigeminal neuronal excitability that can promote migraine pain including that of MRM. Estrogen regulates OT release as well as expression of the OTR. Coincident with menstruation, levels of both estrogen and OT decrease. Additionally, other serum biochemical factors, including magnesium and cholesterol, which positively modulate the affinity of OT for OTRs, both decrease during menstruation. Thus, during menstruation, multiple menstrually associated factors may lead to decreased circulating OT levels, decreased OT affinity for OTR, and decreased expression of the trigeminal OTR. Consistent with the view of migraine as a threshold disorder, these events may collectively result in decreased inhibition promoting lower thresholds for activation of meningeal trigeminal nociceptors and increasing the likelihood of an MRM attack. CONCLUSION Trigeminal OTR may thus be a novel target for the development of MRM therapeutics.
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The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis.
McNulty, KL, Elliott-Sale, KJ, Dolan, E, Swinton, PA, Ansdell, P, Goodall, S, Thomas, K, Hicks, KM
Sports medicine (Auckland, N.Z.). 2020;(10):1813-1827
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Abstract
BACKGROUND Concentrations of endogenous sex hormones fluctuate across the menstrual cycle (MC), which could have implications for exercise performance in women. At present, data are conflicting, with no consensus on whether exercise performance is affected by MC phase. OBJECTIVE To determine the effects of the MC on exercise performance and provide evidence-based, practical, performance recommendations to eumenorrheic women. METHODS This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Four databases were searched for published experimental studies that investigated the effects of the MC on exercise performance, which included at least one outcome measure taken in two or more defined MC phases. All data were meta-analysed using multilevel models grounded in Bayesian principles. The initial meta-analysis pooled pairwise effect sizes comparing exercise performance during the early follicular phase with all other phases (late follicular, ovulation, early luteal, mid-luteal and late luteal) amalgamated. A more comprehensive analysis was then conducted, comparing exercise performance between all phases with direct and indirect pairwise effect sizes through a network meta-analysis. Results from the network meta-analysis were summarised by calculating the Surface Under the Cumulative Ranking curve (SUCRA). Study quality was assessed using a modified Downs and Black checklist and a strategy based on the recommendations of the Grading of Recommendations Assessment Development and Evaluation (GRADE) working group. RESULTS Of the 78 included studies, data from 51 studies were eligible for inclusion in the initial pairwise meta-analysis. The three-level hierarchical model indicated a trivial effect for both endurance- and strength-based outcomes, with reduced exercise performance observed in the early follicular phase of the MC, based on the median pooled effect size (ES0.5 = - 0.06 [95% credible interval (CrI): - 0.16 to 0.04]). Seventy-three studies had enough data to be included in the network meta-analysis. The largest effect was identified between the early follicular and the late follicular phases of the MC (ES0.5 = - 0.14 [95% CrI: - 0.26 to - 0.03]). The lowest SUCRA value, which represents the likelihood that exercise performance is poor, or among the poorest, relative to other MC phases, was obtained for the early follicular phase (30%), with values for all other phases ranging between 53 and 55%. The quality of evidence for this review was classified as "low" (42%). CONCLUSION The results from this systematic review and meta-analysis indicate that exercise performance might be trivially reduced during the early follicular phase of the MC, compared to all other phases. Due to the trivial effect size, the large between-study variation and the number of poor-quality studies included in this review, general guidelines on exercise performance across the MC cannot be formed; rather, it is recommended that a personalised approach should be taken based on each individual's response to exercise performance across the MC.
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Energy Availability Is Associated With Luteinizing Hormone Pulse Frequency and Induction of Luteal Phase Defects.
Koltun, KJ, De Souza, MJ, Scheid, JL, Williams, NI
The Journal of clinical endocrinology and metabolism. 2020;(1):185-93
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OBJECTIVE Determine the interrelations between reductions in energy availability (EA), luteinizing hormone (LH) pulse frequency, and the induction of menstrual disturbances in previously sedentary, ovulatory women. METHODS Secondary analysis of a randomized controlled trial consisting of a 3-month controlled diet and supervised exercise program. EA was calculated daily by measured energy intake (kcal) and exercise energy expenditure (kcal) normalized to fat-free mass (kg) and averaged during baseline and each of 3 intervention menstrual cycles. Blood samples were obtained every 10 minutes for 24 hours in the early follicular phase before the intervention and after 3 months of diet and exercise (n = 14). LH pulse dynamics were assessed by Cluster. Linear mixed models determined whether EA predicts LH pulse frequency and LH pulse frequency predicts luteal phase defects (LPDs). RESULTS Subjects were 20 ± 1 years old, 165.1 ± 1.4 cm tall, and weighed 58.9 ± 1.5 kg. LH pulse frequency decreased from 0.82 ± 0.06 pulses/h to 0.63 ± 0.09 pulses/h (P = 0.048) as a result of the intervention which produced modest (-3.2 ± 0.6 kg) weight loss. EA, averaged across a menstrual cycle, predicted LH pulse frequency (P = 0.003) such that a single-unit decrease in EA was associated with a 0.017 pulses/h decrease in LH pulse frequency. LH pulse frequency in cycles with LPDs was 49% of that observed in cycles with no menstrual disturbances and for every 0.1-unit decrease in LH pulse frequency, the odds of having an LPD were 22× greater than having an optimal ovulatory cycle (P = 0.01). CONCLUSIONS Modest reductions in EA over a prolonged period are associated with decreased LH pulse frequency and the induction of menstrual disturbances.