Expression of aromatase and synthesis of sex steroid hormones in skeletal muscle following exercise training in ovariectomized rats

Unveiling the potential of estrogen: Exploring its role in neuropsychiatric disorders and exercise intervention

Neuropsychiatric disorders shorten human life spans through multiple ways and become major threats to human health. Exercise can regulate the estrogen signaling, which may be involved in depression, Alzheimer's disease (AD) and Parkinson's disease (PD), and other neuropsychiatric disorders as well in their sex differences. In nervous system, estrogen is an important regulator of cell development, synaptic development, and brain connectivity. Therefore, this review aimed to investigate the potential of estrogen system in the exercise intervention of neuropsychiatric disorders to better understand the exercise in neuropsychiatric disorders and its sex specific. Exercise can exert a protective effect in neuropsychiatric disorders through regulating the expression of estrogen and estrogen receptors, which are involved in neuroprotection, neurodevelopment, and neuronal glucose homeostasis. These processes are mediated by the downstream factors of estrogen signaling, including N-myc downstream regulatory gene 2 (Ndrg2), serotonin (5-HT), delta like canonical Notch ligand 1 (DLL1), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), etc. In addition, exercise can act on the estrogen response element (ERE) fragment in the genes of estrogenic downstream factors like β-amyloid precursor protein cleavase 1 (BACE1). However, there are few studies on the relationship between exercise, the estrogen signaling pathway, and neuropsychiatric disorders. Hence, we review how the estrogen signaling mediates the mechanism of exercise intervention in neuropsychiatric disorders. We aim to provide a theoretical perspective for neuropsychiatric disorders affecting female health and provide theoretical support for the design of exercise prescriptions.

Is inflammation a missing link between relative handgrip strength with hyperlipidemia? Evidence from a large population-based study

BACKGROUND

Relative handgrip strength (RHGS) was positively correlated with healthy levels of cardiovascular markers and negatively correlated with metabolic disease risk. However, its association with hyperlipidemia remains unknown. The present study investigated the link between RHGS and hyperlipidemia, utilizing data from the National Health and Nutrition Examination Survey (NHANES) and further examined the hypothesis that inflammation may serve a mediating role within this relationship.

METHODS

Data were extracted from 4610 participants in the NHANES database spanning 2011-2014 to explore the correlation between RHGS and hyperlipidemia using multivariate logistic regression models. Subgroup analyses were conducted to discern the correlation between RHGS and hyperlipidemia across diverse populations. Additionally, smooth curve fitting and threshold effect analysis were conducted to validate the association between RHGS and hyperlipidemia. Furthermore, the potential mediating effect of inflammation on this association was also explored.

RESULTS

According to the fully adjusted model, RHGS was negatively correlated with hyperlipidemia [odds ratio (OR) = 0.575, 95% confidence interval (CI) = 0.515 to 0.643], which was consistently significant across all populations, notably among women. Smooth curve fitting and threshold effect analysis substantiated the negative association between RHGS and hyperlipidemia. Moreover, the mediating effects analysis indicated the white blood cell (WBC) count, neutrophil (Neu) count, and lymphocyte (Lym) count played roles as the mediators, with mediation ratios of 7.0%, 4.3%, and 5.0%, respectively.

CONCLUSIONS

This study identified a prominent negative correlation between RHGS and hyperlipidemia. Elevated RHGS may serve as a protective factor against hyperlipidemia, potentially through mechanisms underlying the modulation of inflammatory processes.

Passive exercise is an effective alternative to HRT for restoring OVX induced mitochondrial dysfunction in skeletal muscle

Background

Postmenopausal women are more prone to develop muscle weakness, which is strongly associated with impairment of mitochondrial function in skeletal muscle. This study aimed to examine the impact of a passive exercise modality, whole-body vibration training (WBVT), on muscle mitochondrial function in ovariectomized (OVX) mice, in comparison with 17β-estradiol (E2) replacement.

Methods

Female C57BL/6J mice were assigned to four groups: sham operation control group (Sham), ovariectomized group (OVX), OVX with E2 supplement group (OVX+E), and OVX with WBVT group (OVX+W). The estrous cycle, body weight, body composition, and muscle strength of the mice were monitored after the operation. Serum E2 level was assessed by enzyme-linked immunosorbent assay (ELISA). The ATP levels were determined using a luciferase-catalyzed bioluminescence assay. The activity of mitochondrial respiration chain complexes was evaluated using high-resolution respirometry (O2K). Expression levels of oxidative phosphorylation (OXPHOS), peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), and mitochondrial transcription factor A (TFAM) were detected using western blotting.

Results

We observed decreased muscle strength and impaired mitochondrial function in the skeletal muscle of OVX mice. The vibration training alleviated these impairments as much as the E2 supplement. In addition, the vibration training was superior to the ovariectomy and the estradiol replacement regarding the protein expression of PGC-1α and TFAM.

Conclusion

WBVT improves the OVX-induced decline in muscle strength and impairment of mitochondrial function in the skeletal muscle. This passive exercise strategy may be useful as an alternative to E2 replacement for preventing menopausal muscular weakness. Further studies are needed to understand the effects of WBVT on various physiological systems, and precautions should be taken when implementing it in patient treatment.

Effect of acute moderate-intensity cycling on cfDNA levels considering menstrual cycle phases

Introduction

We aimed to determine the effects of exercise on cell-free DNA (cfDNA) levels and concentration changes during the menstrual cycle in participants with regular menstrual cycles and no exercise habits.

Methods

Eleven sedentary female students with regular menstrual cycles and ovulation performed bicycle exercises at 60% VO2max for 30 min during the menstrual, ovulatory, and luteal phases. Blood samples were collected before (Pre), immediately after (Post 0), 30 min after (Post 30), and 60 min after (Post 60) exercise. Blood concentrations of ovarian hormones, cfDNA, prostaglandin F2a (PGF2α), interleukin-6 (IL-6), and aromatase were evaluated.

Results

Based on the concentration of ovarian hormones, seven individuals were finally analyzed. No significant phase difference was observed in cfDNA across all time points. cfDNA (menstrual phase: p = 0.028, ovulatory phase: p = 0.018, and luteal phase: p = 0.048) and aromatase concentrations (menstrual phase: p = 0.040, ovulatory phase: p = 0.039, and luteal phase: p = 0.045) significantly increased from Pre to Post 0 in all phases. Serum estradiol (E2) levels were significantly higher in the luteal phase at all time points than in the menstrual phase (Pre: p < 0.001, Post 0: p < 0.001, Post 30: p = 0.005, and Post 60: p = 0.011); however, serum progesterone (P4) levels were significantly higher in the luteal phase at all time points than in the menstrual (Pre: p < 0.001, Post 0: p < 0.001, Post 30: p < 0.001, and Post 60: p < 0.001) and ovulatory phases (Pre: p = 0.005, Post 0: p = 0.005, Post 30: p = 0.003, and Post 60: p = 0.003). E2 levels significantly increased from Pre to Post 0 in the ovulatory and luteal phases, whereas P4 levels increased in the luteal phase. Progesterone to estradiol level ratio (P4/E2) changes from Pre to Post 0 (%baseline) during the luteal phase were significantly negatively correlated (r = -0.82, p = 0.046) with the changes in cfDNA from Pre to Post 0. Furthermore, the repeated measures correlation between P4/E2 and cfDNA level showed a significant negative correlation in ovulatory and luteal phases.

Discussion

The results indicate that while resting cfDNA levels are unlikely to be affected by a woman's menstrual cycle, the increase in cfDNA after exercise is higher in the ovulatory phase (when only E2 increases) and lower in the luteal phase (when E2 and P4 increase with exercise) compared to that in the menstrual phase (when E2 and P4 are in low levels), suggesting the contribution of increased ovarian hormone levels after exercise.

Brain-derived estrogen: a critical player in maintaining cognitive health of aged female rats, possibly involving GPR30

Brain-derived estrogen is an endogenous neuroprotective agent, whether and how might this protective function with aging, especially postmenopausal drops in circulating estrogen, remain unclear. We herein subjected 6, 14, and 18 Mon female rats to mimic natural aging, and found that estrogen synthesis is more active in the healthy aged brain, as evidenced by the highest levels of mRNA and protein expression of aromatase, the key enzyme of E2 biosynthesis, among the three groups. Aromatase knockout in forebrain neurons (FBN-Aro-/-) impaired hippocampal and cortical neurons, and cognitive function in 18 Mon rats, compared to wild-type controls. Furthermore, estrogen nuclear receptors (ERα/β) displayed opposite changes, with a significant ERα decrease and ERβ increase, while membrane receptor GPR30 expressed stably in hippocampus during aging. Intriguingly, GPR30, but not ERα and ERβ, was decreased by FBN-Aro-/-. The results indicate that GPR30 is more sensitive to brain local E2 synthesis. Our findings provide evidence of a critical role for brain-derived estrogen in maintaining healthy brain function in older individuals, possibly involving GPR30.

Cuscuta chinensis flavonoids reducing oxidative stress of the improve sperm damage in bisphenol A exposed mice offspring

Bisphenol A (BPA) is a common environmental endocrine disruptor, and overexposure is a threat to male reproduction. Although studies have confirmed that BPA exposure causes a decrease in sperm quality in offspring, the dosage used, and the underlying mechanism is not clear. The purpose of this study is to investigate whether Cuscuta chinensis flavonoids (CCFs) can antagonize or alleviate BPA-induced reproductive injury by analyzing the processes associated with BPA's impairment of sperm quality. BPA and 40 mg/kg bw/day of CCFs were administered to the dams at gestation day (GD) 0.5-17.5. Testicles and serum of male mice are collected on postnatal day 56 (PND56), and spermatozoa are collected to detect relevant indicators. Our results showed that compared with the BPA group, CCFs could significantly increase the serum contents of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone (T) in males at PND 56, as well as the transcription levels of estrogen receptor alpha (ERα), steroidogenic acute regulatory protein (StAR) and Cytochrome P450 family 11, subfamily A, and member 1 (CYP11A1). CCFs also significantly inhibit the production of reactive oxygen species (ROS), reduce oxidative stress, increase mitochondrial membrane potential, and reduce sperm apoptosis. It also has a certain regulatory effect on sperm telomere length and mitochondrial DNA copy number. These results suggest that CCFs can increase reproductive hormone and receptor levels in adult males by regulating the expression of oxidative stress correlated factors, and ultimately mitigate the negative effects of BPA on sperm quality in male mice.

Estrogen-mediated oar-miR-485-5p targets PPP1R13B to regulate myoblast proliferation in sheep

Ovaries are important endocrine organs in female animals that secrete various steroid hormones, which are involved in multiple physiological functions. Estrogen, one of the hormones secreted by ovaries, is essential for the overall maintenance of muscle growth and development. However, the molecular mechanisms that affect muscle growth and development in sheep following ovariectomy remain unclear. In this study, we identified 1662 differentially expressed mRNAs (DEGs) and 40 differentially expressed miRNAs (DEMs) in sheep that underwent ovariectomy compared with those that underwent sham surgery. A total of 178 DEG-DEM pairs were negatively correlated. GO and KEGG analysis showed that PPP1R13B was involved in the PI3K-Akt signaling pathway, which was essential for muscle development. Using in vitro experiments, we examined the effect of PPP1R13B on myoblast proliferation and found that overexpression or inhibition of PPP1R13B increased or decreased the expression of myoblast proliferation markers, respectively. PPP1R13B was identified as a functional downstream target of miR-485-5p. Our results suggested that miR-485-5p promoted myoblast proliferation by regulating proliferation factors in myoblasts by targeting PPP1R13B. Notably, exogenous estradiol supplementation to myoblasts regulated the expression of oar-miR-485-5p and PPP1R13B and promoted myoblast proliferation. These results provided new insights into the molecular mechanism by which ovaries influence muscle growth and development in sheep.

From mitochondria to sarcopenia: role of 17β-estradiol and testosterone

Sarcopenia, characterized by a loss of muscle mass and strength with aging, is prevalent in older adults. Although the exact mechanisms underlying sarcopenia are not fully understood, evidence suggests that the loss of mitochondrial integrity in skeletal myocytes has emerged as a pivotal contributor to the complex etiology of sarcopenia. Mitochondria are the primary source of ATP production and are also involved in generating reactive oxygen species (ROS), regulating ion signals, and initiating apoptosis signals in muscle cells. The accumulation of damaged mitochondria due to age-related impairments in any of the mitochondrial quality control (MQC) processes, such as proteostasis, biogenesis, dynamics, and mitophagy, can contribute to the decline in muscle mass and strength associated with aging. Interestingly, a decrease in sex hormones (e.g., 17β-estradiol and testosterone), which occurs with aging, has also been linked to sarcopenia. Indeed, 17β-estradiol and testosterone targeted mitochondria and exhibited activities in regulating mitochondrial functions. Here, we overview the current literature on the key mechanisms by which mitochondrial dysfunction contribute to the development and progression of sarcopenia and the potential modulatory effects of 17β-estradiol and testosterone on mitochondrial function in this context. The advance in its understanding will facilitate the development of potential therapeutic agents to mitigate and manage sarcopenia.

Mechanisms of Estrogen Influence on Skeletal Muscle: Mass, Regeneration, and Mitochondrial Function

Human menopause is widely associated with impaired skeletal muscle quality and significant metabolic dysfunction. These observations pose significant challenges to the quality of life and mobility of the aging population, and are of relevance when considering the significantly greater losses in muscle mass and force-generating capacity of muscle from post-menopausal females relative to age-matched males. In this regard, the influence of estrogen on skeletal muscle has become evident across human, animal, and cell-based studies. Beneficial effects of estrogen have become apparent in mitigation of muscle injury and enhanced post-damage repair via various mechanisms, including prophylactic effects on muscle satellite cell number and function, as well as membrane stability and potential antioxidant influences following injury, exercise, and/or mitochondrial stress. In addition to estrogen replacement in otherwise deficient states, exercise has been found to serve as a means of augmenting and/or mimicking the effects of estrogen on skeletal muscle function in recent literature. Detailed mechanisms behind the estrogenic effect on muscle mass, strength, as well as the injury response are beginning to be elucidated and point to estrogen-mediated molecular cross talk amongst signalling pathways, such as apoptotic signaling, contractile protein modifications, including myosin regulatory light chain phosphorylation, and the maintenance of muscle satellite cells. This review discusses current understandings and highlights new insights regarding the role of estrogen in skeletal muscle, with particular regard to muscle mass, mitochondrial function, the response to muscle damage, and the potential implications for human physiology and mobility.

Role of exercise in estrogen deficiency-induced sarcopenia

A decline in estrogen levels during menopause is associated with the loss of muscle mass and function, and it can accelerate sarcopenia. However, with the growing number of postmenopausal women due to the increase in life expectancy, the effects of estrogen on skeletal muscle are not completely understood. This article reviews the relationship between estrogen deficiency and skeletal muscle, its potential mechanisms, including those involving mitochondria, and the effects of exercise on estrogen deficiency-induced skeletal muscle impairment. In particular, mitochondrial dysfunction induced by estrogen deficiency accelerates sarcopenia via mitochondrial dynamics, mitophagy, and mitochondrial-mediated apoptosis. It is well known that exercise training is essential for health, including for the improvement of sarcopenia. This review highlights the importance of exercise training (aerobic and resistance exercise) as a therapeutic intervention against estrogen deficiency-induced sarcopenia.

Exercise Training Attenuates Ovariectomy-Induced Alterations in Skeletal Muscle Remodeling, Apoptotic Signaling, and Atrophy Signaling in Rat Skeletal Muscle

PURPOSE

The effects of aerobic exercise training on soleus muscle morphology, mitochondria-mediated apoptotic signaling, and atrophy/hypertrophy signaling in ovariectomized rat skeletal muscle were investigated.

METHODS

Female Sprague-Dawley rats were divided into control (CON), ovariectomy (OVX), and ovariectomy plus exercise (OVX+EX) groups. After ovarian excision, exercise training was performed using a rat treadmill at 20 m/min, 50 min/day, 5 days/week for 12 weeks. Protein levels of mitochondria-mediated apoptotic signaling and atrophy/hypertrophy signaling in the skeletal muscle (soleus) were examined through western immunoblot analysis.

RESULTS

The number of myocytes and myocyte cross-sectional area (CSA) were increased and the extramyocyte space was decreased in the OVX group compared to those in the CON group. However, aerobic exercise training significantly increased myocyte CSA and decreased extramyocyte space in the OVX+EX group compared to those in the OVX group. The protein levels of proapoptotic signaling and muscle atrophy signaling were significantly increased, whereas the protein levels of muscle hypertrophy signaling were significantly decreased in the OVX group compared to that in the CON group. Aerobic exercise training significantly decreased the protein levels of proapoptotic signaling and increased the protein level of antiapoptotic protein in the OVX+EX group compared to that in the OVX group. Aerobic exercise training significantly increased the protein levels of hypertrophy signaling and decreased protein levels of atrophy signaling in the OVX+EX group compared to those in the OVX group.

CONCLUSION

Treadmill exercise improved estrogen deficiency-induced impairment in skeletal muscle remodeling, mitochondria-mediated apoptotic signaling, and atrophy/hypertrophy signaling in skeletal muscle.

Teriparatide and exercise improve bone, skeletal muscle, and fat parameters in ovariectomized and tail-suspended rats

INTRODUCTION

Although teriparatide (TPTD) and exercise may improve osteoporosis, muscle atrophy, and fat metabolism during ageing, the effects of treatment with a combination of TPTD and exercise on these factors remain unclear. Therefore, this study examined the effects of TPTD and exercise on bone, skeletal muscle, and fat in ovariectomized and tail-suspended rats.

MATERIALS AND METHODS

Seven-month-old female Wistar rats were ovariectomized and subjected to tail suspension. The rats were then randomized into one of the following four groups (n = 20/group) after 4 weeks: control group, treated with TPTD vehicle and no exercise; TPTD group (30 µg/kg TPTD, 3 days/week); Exercise group (treadmill at 12 m/min, 60 min/day, 5 days/week); and Combined group treated with TPTD and treadmill exercise. After 1 and 8 weeks of treatment, bone, skeletal muscle, and fat tissue parameters were evaluated.

RESULTS

TPTD improved bone mineral density (BMD), bone structure, bone strength at the femoral metaphysis, and the percentage of skeletal muscle mass, and decreased the percentage of fat mass and the adipose volume in the bone marrow. Treadmill exercise increased BMD, bone strength of cancellous bone, and the percentage of skeletal muscle mass, and decreased the percentage of fat mass as seen on dual-energy X-ray absorptiometry. Furthermore, combined treatment significantly affected BMD, bone structure, and bone strength of cortical bone at the femoral diaphysis.

CONCLUSION

TPTD or treadmill exercise improved bone, skeletal muscle, and fat mass. Combination therapy with TPTD and exercise had synergistic effects on BMD, structure, and bone strength in ovariectomized, tail-suspended rats.

Mechanical stretch activates glycometabolism-related enzymes via estrogen in C2 C12 myoblasts

Moderate exercise improves glycometabolic disorder and type 2 diabetes mellitus in menopausal females. So far, the effect of exercise-induced estrogen on muscular glycometabolism is not well defined. The current study was designed to explore the effect of mechanical stretch-induced estrogen on glycometabolism in mouse C₂ C₁₂ myoblasts. The mouse C₂ C₁₂ myoblasts in vitro were assigned randomly to the control (C), stretch (S), and stretch plus aromatase inhibitor anastrozole (SA) groups. Cells in the S group were stretched by the Flexcell FX-5000™ system (15% magnitude, 1 Hz frequency, and 6-hr duration) whereas those in the SA group were treated with 400 μg/ml anastrozole before the same stretching. Glucose uptake, estradiol levels, PFK-1 levels, and oxygen consumption rate were determined, and the expression of HK, PI3K, p-AKT, AKT, and GLUT4 proteins were semiquantified with western blot analysis. Compared to the control, the estradiol level, oxygen consumption rate, expression of HK, PI3K, and PFK-1 proteins, the ratio of p-AKT to AKT, and the ratio of GLUT4 in the cell membrane to that in the whole cell were higher in the S group. On the other hand, the estradiol level, glucose uptake, expression of PFK-1 and GLUT4 proteins, oxygen consumption rate, expression of HK protein, and the ratio of p-AKT/AKT were lower in the myoblasts in the SA group than those in the S group. The level of estradiol was positively correlated with glucose uptake (p < .01, r = .818). Therefore, mechanical stretch-induced estrogen increased the expression of glycometabolism-related enzymes and proteins in the mouse C₂ C₁₂ myoblasts.

Biological Sex: A Potential Moderator of Physical Activity Efficacy on Brain Health

The number of older people worldwide living with cognitive impairment and neurodegenerative diseases is growing at an unprecedented rate. Despite accumulating evidence that engaging in physical activity is a promising primary behavioral strategy to delay or avert the deleterious effects of aging on brain health, a large degree of variation exists in study findings. Thus, before physical activity and exercise can be prescribed as “medicine” for promoting brain health, it is imperative to understand how different biological factors can attenuate or amplify the effects of physical activity on cognition at the individual level. In this review article, we briefly discuss the current state of the literature, examining the relationship between physical activity and brain health in older adults and we present the argument that biological sex is a potent moderator of this relationship. Additionally, we highlight some of the potential neurobiological mechanisms underlying this sex difference for this relatively new and rapidly expanding line of research.