Musculoskeletal ageing and primary prevention

Constructing and validating a predictive nomogram for osteoporosis risk among Chinese single-center male population using the systemic immune-inflammation index

Osteoporosis (OP) is a bone metabolism disease that is associated with inflammatory pathological mechanism. Nonetheless, rare studies have investigated the diagnostic effectiveness of immune-inflammation index in the male population. Therefore, it is interesting to achieve early diagnosis of OP in male population based on the inflammatory makers from blood routine examination. We developed a prediction model based on a training dataset of 826 Chinese male patients through a retrospective study, and the data was collected from January 2022 to May 2023. All participants underwent the dual-energy X-ray absorptiometry (DXEA) and blood routine examination. Inflammatory markers such as systemic immune-inflammation index (SII) and platelet-to-lymphocyte ratio (PLR) was calculated and recorded. We utilized the least absolute shrinkage and selection operator (LASSO) regression model to optimize feature selection. Multivariable logistic regression analysis was applied to construct a predicting model incorporating the feature selected in the LASSO model. This predictive model was displayed as a nomogram. Receiver operating characteristic (ROC) curve, C-index, calibration curve, and clinical decision curve analysis (DCA) to evaluate model performance. Internal validation was test by the bootstrapping method. This study was approved by the Ethic Committee of the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine (Ethic No. JY2023012) and conducted in accordance with the relevant guidelines and regulations. The predictive factors included in the prediction model were age, BMI, cardiovascular diseases, cerebrovascular diseases, neuropathy, thyroid diseases, fracture history, SII, PLR, C-reactive protein (CRP). The model displayed well discrimination with a C-index of 0.822 (95% confidence interval: 0.798-0.846) and good calibration. Internal validation showed a high C-index value of 0.805. Decision curve analysis (DCA) showed that when the threshold probability was between 3 and 76%, the nomogram had a good clinical value. This nomogram can effectively predict the incidence of OP in male population based on SII and PLR, which would help clinicians rapidly and conveniently diagnose OP with men in the future.

The impact of ageing mechanisms on musculoskeletal system diseases in the elderly

Ageing is an inevitable process that affects various tissues and organs of the human body, leading to a series of physiological and pathological changes. Mechanisms such as telomere depletion, stem cell depletion, macrophage dysfunction, and cellular senescence gradually manifest in the body, significantly increasing the incidence of diseases in elderly individuals. These mechanisms interact with each other, profoundly impacting the quality of life of older adults. As the ageing population continues to grow, the burden on the public health system is expected to intensify. Globally, the prevalence of musculoskeletal system diseases in elderly individuals is increasing, resulting in reduced limb mobility and prolonged suffering. This review aims to elucidate the mechanisms of ageing and their interplay while exploring their impact on diseases such as osteoarthritis, osteoporosis, and sarcopenia. By delving into the mechanisms of ageing, further research can be conducted to prevent and mitigate its effects, with the ultimate goal of alleviating the suffering of elderly patients in the future.

The Genetic Causal Association between Educational Attainment and Risk of 12 Common Musculoskeletal Disorders: A Two-Sample Mendelian Randomization

OBJECTIVE

In numerous observational studies, there has been an indication that educational attainment (EA) can impact the intensity of pain and disability resulting from chronic musculoskeletal disorders. Nonetheless, the association observed in these studies is not entirely conclusive. The aim of this study was to investigate the genetic causal relationship between educational attainment and 12 musculoskeletal disorders using Mendelian randomization (MR).

METHODS

The meta-analysis of genome-wide association studies (GWAS) identified 3952 single-nucleotide polymorphisms (SNPs) associated with educational attainment (EA) from the Social Science Genetic Association Consortium (SSGAC). Genetic data for 12 musculoskeletal disorders, including osteonecrosis, osteoporosis, osteomyelitis, low back pain, gout, spinal stenosis, rheumatoid arthritis, meniscus derangement, rotator cuff syndrome, ankylosing spondylitis, cervicobrachial syndrome, and lateral epicondylitis, were obtained from the FinnGen consortium. We conducted a two-sample Mendelian randomization analysis to examine the causal effect of EA on the risk of these musculoskeletal disorders using the TwoSampleMR package in R.

RESULTS

Based on the inverse-variance weighted (IVW) method, we found that a genetically predicted per standard deviation (SD) increase in EA was inversely associated with low back pain [odds ratio (OR) 0.46, 95% confidence interval (Cl) 0.51-0.61, p < 0.001], spinal stenosis (OR 0.62, 95% Cl 0.54-0.71, p < 0.001), rheumatoid arthritis (OR 0.65, 95% Cl 0.55-0.76, p < 0.001), meniscus derangement (OR 0.73, 95% Cl 0.65-0.82, p < 0.001), rotator cuff syndrome (OR 0.55, 95% Cl 0.49-0.61, p < 0.001), cervicobrachial syndrome (OR 0.50, 95% Cl 0.42-0.60, p < 0.001), and lateral epicondylitis (OR 0.30, 95% Cl 0.24-0.37, p < 0.001). There was no causal association between EA and osteonecrosis (OR 1.11, 95% CI 0.76-1.72, p = 0.60), osteoporosis (OR 0.91, 95% CI 0.65-1.27, p = 0.59), or osteomyelitis (OR 0.90, 95% CI 0.75-1.01, p = 0.22). Genetic predisposition to EA had a suggestive causal association with gout (OR 0.80, 95% CI 0.68-0.95, p = 0.01) and ankylosing spondylitis (OR 0.64, 95% CI 0.45-0.91, p = 0.01) after Bonferroni correction. None of the analyses revealed any horizontal pleiotropy or heterogeneity.

CONCLUSION

In our investigation, we have uncovered evidence supporting a causal relationship between low level of EA and the incidence of certain musculoskeletal disorders. In the future, it is imperative to ascertain risk factors such as lifestyle patterns linked with EA to uncover the underlying causal relationship and offer informed interventions for individuals.

Rehabilitation: Neurogenic Bone Loss after Spinal Cord Injury

Osteoporosis is a common skeletal disorder which can severely limit one's ability to complete daily tasks due to the increased risk of bone fractures, reducing quality of life. Spinal cord injury (SCI) can also result in osteoporosis and sarcopenia. Most individuals experience sarcopenia and osteoporosis due to advancing age; however, individuals with SCI experience more rapid and debilitating levels of muscle and bone loss due to neurogenic factors, musculoskeletal disuse, and cellular/molecular events. Thus, preserving and maintaining bone mass after SCI is crucial to decreasing the risk of fragility and fracture in vulnerable SCI populations. Recent studies have provided an improved understanding of the pathophysiology and risk factors related to musculoskeletal loss after SCI. Pharmacological and non-pharmacological therapies have also provided for the reduction in or elimination of neurogenic bone loss after SCI. This review article will discuss the pathophysiology and risk factors of muscle and bone loss after SCI, including the mechanisms that may lead to muscle and bone loss after SCI. This review will also focus on current and future pharmacological and non-pharmacological therapies for reducing or eliminating neurogenic bone loss following SCI.

A preliminary study on the barriers and facilitators to improving the health, safety, and well-being of aging heavy vehicle drivers

INTRODUCTION

Managers from road freight transportation organizations were interviewed on barriers and facilitators to implementation of occupational health, safety, and well-being interventions for aging heavy vehicle drivers. As aging drivers are more likely to be seriously injured or die in a work-related incident than younger drivers, it is important to recognize strengths and weaknesses throughout the system to identify intervention that addresses their specific needs.

METHOD

A Systems Theoretic Accident Model and Processes (STAMP) control structure was constructed to chart the controllers, controls, and feedback channels in the system to identify gaps in health, safety, and well-being intervention in the system. The STAMP control structure also charted the barriers and facilitators within levels across the system. Eleven managers were recruited into the study representing a range of road freight transportation organizations throughout Australia.

RESULTS

Interview data revealed that barriers and facilitators existed at most levels of the system. Facilitators included advice from external agencies, support from upper management, modern technology, and regular social communication with drivers. Barriers were a lack of guidance on aging issues, operational conflicts with health and safety objectives, and the drivers' fear of disclosing health information associated with their driving role. In regards to formalized intervention in place to support aging heavy vehicle drivers, the system is reliant on fitness to drive medical assessments based on age and jurisdiction.

CONCLUSIONS

As there was generally a lack of senior direction cited from the upper levels of the system on aging issues, there was much variation across the study on how aging risks are managed in the workplace for heavy vehicle drivers.

PRACTICAL APPLICATIONS

This study recommends that managers across the road freight transportation industry receive formalized aging-awareness health and safety training in how to manage work-related driving hazards for aging heavy vehicle drivers.

Recovery from Resistance Exercise in Older Adults: A Systematic Scoping Review

BACKGROUND

Resistance exercise is recommended for maintaining muscle mass and strength in older adults. However, little is known about exercise-induced muscle damage and recovery from resistance exercise in older adults. This may have implications for exercise prescription. This scoping review aimed to identify and provide a broad overview of the available literature, examine how this research has been conducted, and identify current knowledge gaps relating to exercise-induced muscle damage and recovery from resistance exercise in older adults.

METHODS

Studies were included if they included older adults aged 65 years and over, and reported any markers of exercise-induced muscle damage after performing a bout of resistance exercise. The following electronic databases were searched using a combination of MeSH terms and free text: MEDLINE, Scopus, Embase, SPORTDiscus and Web of Science. Additionally, reference lists of identified articles were screened for eligible studies. Data were extracted from eligible studies using a standardised form. Studies were collated and are reported by emergent theme or outcomes.

RESULTS

A total of 10,976 possible articles were identified and 27 original research articles were included. Findings are reported by theme; sex differences in recovery from resistance exercise, symptoms of exercise-induced muscle damage, and biological markers of muscle damage.

CONCLUSIONS

Despite the volume of available data, there is considerable variability in study protocols and inconsistency in findings reported. Across all measures of exercise-induced muscle damage, data in women are lacking when compared to males, and rectifying this discrepancy should be a focus of future studies. Current available data make it challenging to provide clear recommendations to those prescribing resistance exercise for older people.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: Hype or Hope for Skeletal Muscle Anti-Frailty

Steadily rising population ageing is a global demographic trend due to the advancement of new treatments and technologies in the medical field. This trend also indicates an increasing prevalence of age-associated diseases, such as loss of muscle mass (sarcopenia), which tends to afflict the older population. The deterioration in muscle function can cause severe disability and seriously affects a patient's quality of life. Currently, there is no treatment to prevent and reverse age-related skeletal muscle ageing frailty. Existing interventions mainly slow down and control the signs and symptoms. Mesenchymal stem cell-derived extracellular vesicle (MSC-EV) therapy is a promising approach to attenuate age-related skeletal muscle ageing frailty. However, more studies, especially large-scale randomised clinical trials need to be done in order to determine the adequacy of MSC-EV therapy in treating age-related skeletal muscle ageing frailty. This review compiles the present knowledge of the causes and changes regarding skeletal muscle ageing frailty and the potential of MSC-EV transplantation as a regenerative therapy for age-related skeletal muscle ageing frailty and its clinical trials.

Mesenchymal Stem Cell Transplantation for the Treatment of Age-Related Musculoskeletal Frailty

Projected life expectancy continues to grow worldwide owing to the advancement of new treatments and technologies leading to rapid growth of geriatric population. Thus, age-associated diseases especially in the musculoskeletal system are becoming more common. Loss of bone (osteoporosis) and muscle (sarcopenia) mass are conditions whose prevalence is increasing because of the change in population distribution in the world towards an older mean age. The deterioration in the bone and muscle functions can cause severe disability and seriously affects the patients’ quality of life. Currently, there is no treatment to prevent and reverse age-related musculoskeletal frailty. Existing interventions are mainly to slow down and control the signs and symptoms. Mesenchymal stem cell (MSC) transplantation is a promising approach to attenuate age-related musculoskeletal frailty. This review compiles the present knowledge of the causes and changes of the musculoskeletal frailty and the potential of MSC transplantation as a regenerative therapy for age-related musculoskeletal frailty.

Work-related Hazards Among Pathologists and Residents of Pathology:Results of a Cross-sectional Study in Iran

BACKGROUND & OBJECTIVE

Pathologists as medical professionals involved in the diagnosis and planning of therapies in many diseases are exposed to occupational hazards in workplaces. Hence, we aimed to determine the occupational health problems among Iranian pathologists in this cross-sectional study.

METHODS

This cross-sectional study was conducted among the Iranian pathologists. The data required for this study was collected through a self-reported questionnaire containing 48 questions about major occupational health problems, including musculoskeletal problems, visual disorders, workplace characteristics, health behavior, and other medical conditions.

RESULTS

Among the study participants (N=350), 87.4% presented with musculoskeletal disorders in the past year, with the neck as the most common location of pain (71%). Musculoskeletal pain was significantly higher in those working with the computer for more than 5 hours per day (P=0.007). Furthermore, 273 (78%) participants reported visual refractive errors, and myopia was the most common error (53%). Acute injuries were reported in 263 (75%) participants, and the cutting injury had the highest frequency (56.6%). Depression was reported in 54 (15.4%) of the participants, followed by burnout (10.3%) and hypertension (4%). Intolerance reactions to formalin were reported by 222 (63.6%) and were significantly more frequent among the residents (P<0.001). The residents were more prone to musculoskeletal pain (P=0.002) and injury (P=0.026).

CONCLUSION

We observed a noticeable prevalence of health risks, including musculoskeletal problems, visual disturbances, injuries, and ergonomic problems among the Iranian pathologists. Solving these problems demands thorough prevention and personal protection, as well as educational programs with more attention toward optimization of ergonomics in the workplace and awareness about chemical and biological hazards.

Exercise and Diet: Uncovering Prospective Mediators of Skeletal Fragility in Bone and Marrow Adipose Tissue

PURPOSE OF REVIEW

To highlight recent basic, translational, and clinical works demonstrating exercise and diet regulation of marrow adipose tissue (MAT) and bone and how this informs current understanding of the relationship between marrow adiposity and musculoskeletal health.

RECENT FINDINGS

Marrow adipocytes accumulate in the bone in the setting of not only hypercaloric intake (calorie excess; e.g., diet-induced obesity) but also with hypocaloric intake (calorie restriction; e.g., anorexia), despite the fact that these states affect bone differently. With hypercaloric intake, bone quantity is largely unaffected, whereas with hypocaloric intake, bone quantity and quality are greatly diminished. Voluntary running exercise in rodents was found to lower MAT and promote bone in eucaloric and hypercaloric states, while degrading bone in hypocaloric states, suggesting differential modulation of MAT and bone, dependent upon whole-body energy status. Energy status alters bone metabolism and bioenergetics via substrate availability or excess, which plays a key role in the response of bone and MAT to mechanical stimuli. Marrow adipose tissue (MAT) is a fat depot with a potential role in-as well as responsivity to-whole-body energy metabolism. Understanding the localized function of this depot in bone cell bioenergetics and substrate storage, principally in the exercised state, will aid to uncover putative therapeutic targets for skeletal fragility.

Work ability, functional exercise capacity and prevalence of obesity in perimenopausal and postmenopausal women with non-manual employment

Objective. This study aimed to evaluate work ability and functional exercise capacity, and their correlation to each other and to obesity, in perimenopausal and postmenopausal women with non-manual employment. Materials and methods. The study included 300 women aged 44-66 years. The following measures were used: work ability index (WAI), 6-min walk test (6MWT), body mass index (BMI), waist-hip ratio (WHR) and adipose tissue accumulation. Regression models of the WAI and distance in the 6MWT were estimated. Results. The examined women obtained WAI 39.0 ± 5.0, BMI 26.2 ± 4.6, WHR 0.819 ± 0.060 and adipose tissue accumulation 30.1 ± 6.1%, on average. About 19% of women obtained a very good work ability score, 55% good, 23% medium and 3% poor. About 17% of women were obese, 39% overweight and 44% normal body mass, 29% had abdominal obesity, 19% had elevated accumulation of adipose tissue and 21% had high accumulation of adipose tissue. These results did not differ significantly between perimenopausal and postmenopausal women The postmenopausal women obtained a significantly lower functional exercise capacity score than perimenopausal women. Conclusion. Work ability correlates positively to functional exercise capacity, which correlates negatively to adipose tissue accumulation in perimenopausal women with non-manual employment, but not in postmenopausal cases.

Considerations of elderly factors to manage the complication of liver cirrhosis in elderly patients

The aging of the organ function causes sensitivity to the disease progression and need careful consideration for the medical treatment. With the increase of aging population, the opportunity to provide medical treatment for people in very old age is rapidly increasing therefore, the understanding of the various physiological changes of cellular function, size and function of organs are essential for the decision of therapeutic options. Among the various chronic conditions seen in elderly people, we have focused on liver cirrhosis, since despite specific therapeutic options for many of liver diseases including direct acting antivirals for hepatitis C virus, nucleoside analogs for hepatitis B, and corticosteroids for autoimmune hepatitis, there is currently no standard therapy to treat liver cirrhosis, which is the final stage of these liver diseases. Therefore, management of the various symptoms of liver cirrhosis is essential, and aging-related parameters must be considered in the decision making for therapeutic strategies and dosage of the available medicine. In this mini-review, we have summarized the therapeutic options to manage various symptoms of liver cirrhosis, carefully considering the physiological changes of various organs associated with aging.

Mitochondria and cellular senescence: Implications for musculoskeletal ageing

Musculoskeletal ageing and its associated diseases are major contributors to the loss of independence and reduced quality of life in older people. Several recent studies indicate that cellular senescence is a contributor to age-related loss of function in various organs including muscle, bones and joints. Importantly, these studies indicate that therapies targeting specifically senescent cells have great therapeutic potential in improving musculoskeletal health during ageing. Senescent cells are characterised by dramatic changes in mitochondrial function, metabolism and homeostasis. Mitochondrial dysfunction has been shown to contribute to senescence and the SASP. Here we review the role of cellular senescence in musculoskeletal ageing as well as the potential mechanisms by which mitochondrial dysfunction may impact on the induction and development of the senescent phenotype.

The Association Between Musculoskeletal Symptoms and Traditional Chinese Medicine Use Among Chinese Older Adults in the Greater Chicago Area

Older adults disproportionately experience musculoskeletal symptoms, which are associated with morbidity and mortality. Traditional Chinese medicine (TCM) is an important part of Chinese culture and for millennia have been used to maintain health. This article aims to examine the association between musculoskeletal symptoms and different subtypes of TCM usage. Data were collected through the Population Study of Chinese Elderly in Chicago (PINE) study, a community-engaged, epidemiological study of a U.S. Chinese population. Review of systems was used to measure musculoskeletal symptoms. TCM use was measured by using a 5-point scale. Logistic regression analyses were conducted to control for potential confounding factors. Of 3,157 Chinese, older adults aged 60 and older, the mean age was 72.8 (SD = 8.3) and 58.9% were female. Older adults with any musculoskeletal symptoms had greater utilization of overall TCM use (odds ratio [OR] = 2.10, 95% confidence interval [CI] = [1.76, 2.52]), especially massage therapy (OR = 3.41, 95% CI = [2.51, 4.63]), herbal (OR = 2.68, 95% CI = [2.28, 3.14]), and acupuncture (OR = 2.49, 95% CI = [1.87, 3.32]). However, there was no statistically significant association between the presence of musculoskeletal symptoms and Tai-Chi (OR = 1.18, 95% CI = [0.93, 1.50]). This study demonstrated that musculoskeletal symptoms among Chinese older adults were strongly associated with the use of TCM. Future research is needed to examine the effectiveness of TCM in treating musculoskeletal symptoms.

Augmentation of musculoskeletal regeneration: role for pluripotent stem cells

The rise in the incidence of musculoskeletal diseases is attributed to an increasing ageing population. The debilitating effects of musculoskeletal diseases, coupled with a lack of effective therapies, contribute to huge financial strains on healthcare systems. The focus of regenerative medicine has shifted to pluripotent stem cells (PSCs), namely, human embryonic stem cells and human-induced PSCs, due to the limited success of adult stem cell-based interventions. PSCs constitute a valuable cell source for musculoskeletal regeneration due to their capacity for unlimited self-renewal, ability to differentiate into all cell lineages of the three germ layers and perceived immunoprivileged characteristics. This review summarizes methods for chondrogenic, osteogenic, myogenic and adipogenic differentiation of PSCs and their potential for therapeutic applications.

Physiology of ageing of the musculoskeletal system

This review aims to provide a summary of current concepts of ageing in relation to the musculoskeletal system, highlighting recent advances in the understanding of the mechanisms involved in the development of age-related changes in bone, skeletal muscle, chondroid and fibrous tissues. The key components of the musculoskeletal system and their functions are introduced together with a general overview of the molecular hallmarks of ageing. A brief description of the normal architecture of each of these tissue types is followed by a summary of established and developing concepts of mechanisms contributing to the age-related alterations in each. Extensive detailed description of these changes is beyond the scope of this review; instead, we aim to highlight some of the most significant processes and, where possible, the molecular changes underlying these and refer the reader to in-depth, subspecialist reviews of the individual components for further details.

The effect of estrogen on tendon and ligament metabolism and function

Tendons and ligaments are crucial structures inside the musculoskeletal system. Still many issues in the treatment of tendon diseases and injuries have yet not been resolved sufficiently. In particular, the role of estrogen-like compound (ELC) in tendon biology has received until now little attention in modern research, despite ELC being a well-studied and important factor in the physiology of other parts of the musculoskeletal system. In this review we attempt to summarize the available information on this topic and to determine many open questions in this field.

Thoracic muscle cross-sectional area is associated with hospital length of stay post lung transplantation: a retrospective cohort study

Low muscle mass is common in lung transplant (LTx) candidates; however, the clinical implications have not been well described. The study aims were to compare skeletal muscle mass in LTx candidates with controls using thoracic muscle cross-sectional area (CSA) from computed tomography and assess the association with pre- and post-transplant clinical outcomes. This was a retrospective, single-center cohort study of 527 LTx candidates [median age: 55 IQR (42-62) years; 54% male]. Thoracic muscle CSA was compared to an age- and sex-matched control group. Associations between muscle CSA and pre-transplant six-minute walk distance (6MWD), health-related quality of life (HRQL), delisting/mortality, and post-transplant hospital outcomes and one-year mortality were evaluated using multivariable regression analysis. Muscle CSA for LTx candidates was about 10% lower than controls (n = 38). Muscle CSA was associated with pre-transplant 6MWD, but not HRQL, delisting or pre- or post-transplant mortality. Muscle CSA (per 10 cm² difference) was associated with shorter hospital stay [0.7 median days 95% CI (0.2-1.3)], independent of 6MWD. In conclusion, thoracic muscle CSA is a simple, readily available estimate of skeletal muscle mass predictive of hospital length of stay, but further study is needed to evaluate the relative contribution of muscle mass versus functional deficits in LTx candidates.

Moderate Load Eccentric Exercise; A Distinct Novel Training Modality

Over the last 20 years a number of studies have been published using progressive eccentric exercise protocols on motorized ergometers or similar devices that allow for controlled application of eccentric loads. Exercise protocols ramp eccentric loads over an initial 3 weeks period in order to prevent muscle damage and delayed onset muscle soreness. Final training loads reach 400-500 W in rehabilitative settings and over 1200 W in elite athletes. Training is typically carried out three times per week for durations of 20-30 min. This type of training has been characterizes as moderate load eccentric exercise. It has also been denoted RENEW (Resistance Exercise via Negative Eccentric Work by LaStayo et al., 2014). It is distinct from plyometric exercises (i.e., drop jumps) that impose muscle loads of several thousand Watts on muscles and tendons. It is also distinct from eccentric overload training whereby loads in a conventional strength training setting are increased in the eccentric phase of the movement to match concentric loads. Moderate load eccentric exercise (or RENEW) has been shown to be similarly effective as conventional strength training in increasing muscle strength and muscle volume. However, as carried out at higher angular velocities of joint movement, it reduces joint loads. A hallmark of moderate load eccentric exercise is the fact that the energy requirements are typically 4-fold smaller than in concentric exercise of the same load. This makes moderate load eccentric exercise training the tool of choice in medical conditions with limitations in muscle energy supply. The use and effectiveness of moderate load eccentric exercise has been demonstrated mostly in small scale studies for cardiorespiratory conditions, sarcopenia of old age, cancer, diabetes type 2, and neurological conditions. It has also been used effectively in the prevention and rehabilitation of injuries of the locomotor system in particular the rehabilitation after anterior cruciate ligament surgery.

BA321, a novel carborane analog that binds to androgen and estrogen receptors, acts as a new selective androgen receptor modulator of bone in male mice

Carboranes are a class of carbon-containing polyhedral boron cluster compounds with globular geometry and hydrophobic surface that interact with hormone receptors such as estrogen receptor (ER) and androgen receptor (AR). We have synthesized BA321, a novel carborane compound, which binds to AR. We found here that it also binds to ERs, ERα and ERβ. In orchidectomized (ORX) mice, femoral bone mass was markedly reduced due to androgen deficiency and BA321 restored bone loss in the male, whilst the decreased weight of seminal vesicle in ORX mice was not recovered by administration of BA321. In female mice, BA321 acts as a pure estrogen agonist, and restored both the loss of bone mass and uterine atrophy due to estrogen deficiency in ovariectomized (OVX) mice. In bone tissues, the trabecular bone loss occurred in both ORX and OVX mice, and BA321 completely restored the trabecular bone loss in both sexes. Cortical bone loss occurred in ORX mice but not in OVX mice, and BA321 clearly restored cortical bone loss due to androgen deficiency in ORX mice. Therefore, BA321 is a novel selective androgen receptor modulator (SARM) that may offer a new therapy option for osteoporosis in the male.

Activation of GPR30 improves exercise capacity and skeletal muscle strength in senescent female Fischer344 × Brown Norway rats

The molecular mechanisms of muscle weakness and sarcopenia in postmenopausal women are largely unknown. To determine the effect of a new estrogen receptor, GPR30, in the maintenance of exercise capacity and skeletal muscle function in females, the selective GPR30 agonist, G1 (100 μg/kg/day), or vehicle (V, soybean oil) was administered subcutaneously daily (n = 7 per group) to ovariectomized (OVX) 27-month-old Fischer 344 × Brown Norway (F344BN) female rats. Following 8 weeks of treatment, the exercise capacity (treadmill walk time to exhaustion) was reduced in OVX vs. sham rats (5.1 ± 1.4 vs. 11.0 ± 0.9 min, P < 0.05), and chronic G1 restored exercise capacity (12.9 ± 1.2 min; P < 0.05 vs. OVX-V). Similarly, the peak twitch of electrically stimulated soleus muscles was decreased by 22% in OVX vs. sham rats (P < 0.05), and G1 attenuated this decline (P < 0.05). Western blot analysis showed that chronic G1 treatment attenuated OVX-associated decreases in heat shock protein (HSP) 90, HSP70, and HSP27 expressions. In vitro studies using the L6 myoblast cell line demonstrated that G1 increased mRNA levels of HSPs in cultured cells. Collectively, these data demonstrate that the activation of GPR30 mitigates the adverse effects of estrogen loss on exercise capacity and skeletal muscle contractile function in old F344BN rats. The protective effects of GPR30 might be through its upregulation of heat shock proteins in skeletal muscle.