A change of osteocalcin (OC) and tartrate resistant acid phosphatase 5b (TRACP-5b) with the menstrual cycle

Effects of Psychogenic Stress Frequency during the Growth Stage on Oxidative Stress, Organ and Bone Development

BACKGROUND

This study aimed to examine the effects of psychogenic stress (PS) frequency on oxidative stress and organ development during growth and to gain fundamental insights into developmental processes during this period.

METHODS

Four-week-old male Wistar rats were randomly assigned to a control and three PS groups according to PS frequencies. PS was induced using restraint and water immersion techniques once daily for 3 hr at a time for a period of 4 weeks.

RESULTS

Oxidative stress increased with increasing PS frequency. The weights of organs other than the adrenal glands significantly decreased with increasing PS frequency, indicating growth suppression. Furthermore, bone morphology, weight, and length significantly decreased with increasing PS frequency.

CONCLUSIONS

High-frequency PS exposure during developmental growth significantly negatively affects oxidative stress and organ and bone development. In particular, increased oxidative stress due to excessive PS has detrimental effects on organ and bone growth.

Impact of menopause-associated frailty on traumatic brain injury

Navigating menopause involves traversing a complex terrain of hormonal changes that extend far beyond reproductive consequences. Menopausal transition is characterized by a decrease in estradiol-17β (E2), and the impact of menopause resonates not only in the reproductive system but also through the central nervous system, musculoskeletal, and gastrointestinal domains. As women undergo menopausal transition, they become more susceptible to frailty, amplifying the risk and severity of injuries, including traumatic brain injury (TBI). Menopause triggers a cascade of changes leading to a decline in muscle mass, accompanied by diminished tone and excitability, thereby restricting the availability of irisin, a crucial hormone derived from muscles. Concurrently, bone mass undergoes reduction, culminating in the onset of osteoporosis and altering the dynamics of osteocalcin, a hormone originating from bones. The diminishing levels of E2 during menopause extend their influence on the gut microbiota, resulting in a reduction in the availability of tyrosine, tryptophan, and serotonin metabolites, affecting neurotransmitter synthesis and function. Understanding the interplay between menopause, frailty, E2 decline, and the intricate metabolisms of bone, gut, and muscle is imperative when unraveling the nuances of TBI after menopause. The current review underscores the significance of accounting for menopause-associated frailty in the incidence and consequences of TBI. The review also explores potential mechanisms to enhance gut, bone, and muscle health in menopausal women, aiming to mitigate frailty and improve TBI outcomes.

Osteocalcin, ovarian senescence, and brain health

Menopause, an inevitable event in a woman's life, significantly increases risk of bone resorption and diseases such as Alzheimer's, vascular dementia, cardiac arrest, and stroke. The sole role of bones, as traditionally regarded, is to provide structural support for skeletal muscles and allow for ambulation, however this concept is becoming quickly outdated. New literature has emerged that suggests the bone cell-derived hormone osteocalcin (OCN) plays a pivotal role in cognition. OCN levels are correlated with bone mass density and bone turnover, and thus are strongly influenced by the changes associated with menopause. The goal of the current review is to discuss potential gaps in our knowledge of OCN and cognition, discrepancies in methods of OCN quantification, and therapies to enhance circulating OCN. A discussion on implementing exercise or low frequency vibration interventions at the menopausal transition to reduce risk and severity of neurological diseases and associated cognitive decline is included.

Novel bone metabolism-associated hormones: the importance of the pre-analytical phase for understanding their physiological roles

The endocrine function of bone is now a recognized feature of this tissue. Bone-derived hormones that modulate whole-body homeostasis, are being discovered as for the effects on bone of novel and classic hormones produced by other tissues become known. Often, however, the data regarding these last generation bone-derived or bone-targeting hormones do not give about a clear picture of their physiological roles or concentration ranges. A certain degree of uncertainty could stem from differences in the pre-analytical management of biological samples. The pre-analytical phase comprises a series of decisions and actions (i.e., choice of sample matrix, methods of collection, transportation, treatment and storage) preceding analysis. Errors arising in this phase will inevitably be carried over to the analytical phase where they can reduce the measurement accuracy, ultimately, leading discrepant results. While the pre-analytical phase is all important, in routine laboratory medicine, it is often not given due consideration in research and clinical trials. This is particularly true for novel molecules, such as the hormones regulating the endocrine function of bone. In this review we discuss the importance of the pre-analytical variables affecting the measurement of last generation bone-associated hormones and describe their, often debated and rarely clear physiological roles.

The Influence of the Type of Continuous Exercise Stress Applied during Growth Periods on Bone Metabolism and Osteogenesis

Background

In this study, we examined the influence of exercise loading characteristics on bone metabolic responses and bone morphology in the growth phase and adulthood.

Methods

Running exercise (RUN) and jumping exercise (JUM) were used for the exercise loading in 28-day-old male Wistar rats. Bone metabolism was measured by blood osteocalcin (OC) and tartrate-resistant acid phosphatase (TRACP) levels. For bone morphology, the maximum bone length, bone weight, and bone strength of the femur and tibia were measured.

Results

A pre- and post-exercise loading comparison in the growth phase showed significantly increased OC levels in the RUN and JUM groups and significantly decreased TRACP levels in the JUM group. On the other hand, a pre- and post-exercise loading comparison in adulthood showed significantly decreased TRACP levels in the RUN and JUM groups. Femur lengths were significantly shorter in the RUN and JUM groups than in the control (CON) group, while bone weight was significantly greater in the JUM group than in the CON group.

Conclusions

Exercise loading activates OC levels in the growth phase and suppresses TRACP levels in adulthood. On the other hand, these results suggest that excessive exercise loading may suppress bone length.

Effects of dietary resveratrol on excess-iron-induced bone loss via antioxidative character

Estrogen deficiency has been considered to be a major cause of osteoporosis, but recent epidemiological evidence and mechanistic studies have indicated that aging and the associated increase in reactive oxygen species (ROS) are the proximal pathogenic factors. Through ROS-mediated reactions, iron can induce disequilibrium of oxidation and antioxidation and can cause bone loss in mice. Therefore, we investigated the effects of resveratrol (RES) on bone mineral density, bone microstructure and the osteoblast functions under iron-overload conditions. Excess iron disrupted the antioxidant/prooxidant equilibrium of the mice and induced the defect and the lesion of the bone trabecula as well as disequilibrium between bone formation and bone resorption in iron-overload mice. Oral administration of RES significantly prevented bone loss in the osteoporotic mice. RES reversed the reduction of Runx2, OCN and type I collagen from excess iron; up-regulated the level of FOXO1; and maintained the antioxidant/prooxidant equilibrium in the mice. RES also reduced the ratio of OPG/RANKL in MC3T3-E1 cells and in mice and significantly inhibited subsequent osteoclastogenesis. These results provide new insights into the antiosteoporosis mechanisms of RES through antioxidative effects, suggesting that RES can be considered a potential natural resource for developing medicines or dietary supplements to prevent and treat osteoporosis.

Elevated serum soluble CD200 and CD200R as surrogate markers of bone loss under bed rest conditions

CD200 is a transmembrane protein that belongs to the immunoglobulin family of proteins and is ubiquitously expressed on a variety of cell types. Upon interaction with its receptors (CD200Rs) expressed on myeloid-derived cells and T lymphocytes, an immunoregulatory signal is delivered to receptor-expressing cells. Previous studies have implicated a role for CD200:CD200R in the regulation of the expression of mRNA markers of osteoclastogenesis/osteoblastogenesis, following interaction of CD200 (on osteoblast precursors) with CD200R1 (on osteoclast precursors). Signaling of CD200R1 is hypothesized to attenuate osteoclastogenesis. We have investigated whether levels of soluble forms of CD200 and/or CD200R1 (sCD200, sCD200R1) are altered in volunteers undergoing 6° head down tilt bed rest to mimic conditions of microgravity known to be associated with preferential osteoclastogenesis and whether countermeasures, reported to be beneficial in attenuation of bone loss under microgravity conditions, would lead to altered sCD200 and sCD200R1 levels. Our data suggest that, as predicted, sCD200 levels fall under bed rest conditions while sCD200R1 levels rise. In subjects undergoing 30-minute per day continuous centrifugation protocols, as a countermeasure to attenuate changes which may lead to bone loss, these alterations in sCD200 and sCD200R1 levels seen under conditions of bed rest were abolished or attenuated. Our results suggest that measurement of sCD200 and/or sCD200R1 may prove a useful and rapid means of monitoring subjects at risk of bone loss and/or accessing the efficacy of treatment regimes designed to counter bone loss.