Analysis of correlation between blood biochemical indicators and bone mineral density of post-menopausal women

Bone Marrow Mesenchymal Stem Cells-Derived Exosomal MicroRNA-150-3p Promotes Osteoblast Proliferation and Differentiation in Osteoporosis

At present, much more studies have focused on the role of microRNAs in osteoporosis, but the more specific role of microRNA-150-3p (miR-150-3p) in osteoporosis still needs full exploration. We aim at investigating the role of miR-150-3p in osteoporosis and at exploring the related mechanisms. Bone marrow mesenchymal stem cells (BMSCs) were cultured, from which exosomes were isolated. Osteoporosis models were established by ovariectomy and injected with transfected BMSCs exosomes. Bone formation markers in serum, histopathological changes and miR-150-3p, runt-related transcription factor 2 (Runx2) and Osterix expression, and osteoblast apoptosis in femoral tissues were detected. Osteoblasts were isolated and co-cultured with the transfected BMSCs-derived exosomes. Osteoblast proliferation, cell differentiation, and apoptosis, along with miR-150-3p, Runx2, and Osterix expression in osteoblasts were detected. In vivo experiment demonstrated that miR-150-3p, Runx2, and Osterix expression was decreased whereas bone formation markers were decreased in osteoporosis. BMSCs exosomes attenuated osteoporosis, which was further improved by upregulated miR-150-3p in exosomes whereas it was impaired by downregulated miR-150-3p in exosomes. In vitro experiments declared decreased miR-150-3p, Runx2, and Osterix expression; suppressed proliferation; and encouraged apoptosis in osteoblasts in osteoporosis. BMSCs exosomes promoted osteoblast proliferation and differentiation and inhibited apoptosis, which was strengthened by raised exosomal miR-150-3p whereas it was disrupted by inhibited exosomal miR-150-3p. Our study elucidates that exosomal miR-150-3p promotes osteoblast proliferation and differentiation in osteoporosis and provides a new clue for the treatment of patients with osteoporosis.

Correlation of oxidative stress-related biomarkers with postmenopausal osteoporosis: a systematic review and meta-analysis

Oxidative stress (OS) is implicated in postmenopausal osteoporosis (PO). Results show an imbalance between antioxidative and oxidative markers in PO. Thus, monitoring of OS-related biomarkers and keeping balance between reactive oxygen species and antioxidant system are beneficial to the diagnosis and prognosis of PO.

PURPOSE

Oxidative stress (OS) has been implicated in postmenopausal osteoporosis (PO). However, the relations between OS-related markers and PO are controversial. This study aimed to quantitatively and comprehensively assess the roles of OS-related biomarkers in PO.

METHODS

Relevant articles were retrieved from electronic databases. All OS-associated biomarkers with at least 2 independent study outcomes were meta-analyzed. The pooled standardized mean differences (SMD) with its 95% confidence intervals (CI) were presented.

RESULTS

A total of 36 studies involving 16 OS-related biomarkers were investigated. The overall results showed that total oxidant status (TOS), superoxide dismutase (SOD), hydroperoxides (HY), paraoxonase (PON1), nitric oxide (NO), and homocysteine (Hcy) were not statistically different between the PO and control groups, whereas significantly increased levels of oxidative stress index (OSI), malondialdehyde (MDA), advanced oxidation protein products (AOPP), and vitamin B12, along with decreased total antioxidant status (TAS), total antioxidant power (TAP), catalase (CAT), glutathione peroxidase (GPx), uric acid (UA), and folate, were detected in the PO group. Subgroup analysis based on biological samples displayed significantly elevated NO in erythrocyte and Hcy in serum, along with decreased SOD in serum.

CONCLUSION

Monitoring of certain OS-related biomarkers might be beneficial to the diagnosis and prognosis of PO.

Increased Plasma Osteocalcin, Oral Disease, and Altered Mandibular Bone Density in Postmenopausal Women

An association between oral diseases and postmenopausal status has been recognized. However, the relationship between all oral disease, mandibular bone density, health status, and osteocalcin (OCN) bone markers in postmenopausal dental patients has not been reported. This study was therefore to verify the differences in plasma OCN levels, dental, periodontal, and oral mucosal disease, and mandibular bone density alterations from panoramic radiograph and systemic parameters in postmenopausal women, compared to premenopausal women. Oral, radiographic, and blood examination were performed in 92 females. Dental, periodontal, and oral mucosal statuses were recorded. Health profile parameters were collected from medical charts. Plasma OCN was evaluated by enzyme-linked immunosorbent assay. Forty-two (45.7%) participants were postmenopausal with a higher median age (55 (51, 62) years) than the premenopausal group (43 (38, 45) years). Overweight or obesity, hypercholesterolemia, and impaired fasting blood sugar were more prevalent in postmenopause. The average postmenopausal OCN level (425.62 ng/mL) was significantly higher than the premenopausal group (234.77 ng/mL, p < 0.001). The average number of missing teeth, mean attachment loss, alveolar bone loss, periapical lesion count, and clinical oral dryness score were also significantly higher in postmenopause (p=0.008,   < 0.001,  0.031,  0.006,  and 0.005, respectively). However, mandibular bone density determined by mandibular cortical index was lower in postmenopause (p < 0.001). The panoramic mandibular index, mandibular cortical width, fractal dimension, and other oral mucosal disease did not differ between the groups. Postmenopause was associated with elevated plasma OCN (β = 0.504, p < 0.001) when related covariates were adjusted. Elevated plasma OCN, oral mucosal dryness, high number of periapical radiolucencies and missing teeth, and lower mandibular bone density from panoramic radiograph were prevalent in postmenopausal women. Dentists should suspect an increased risk of low bone mineral density in postmenopausal patients who display these clinical and radiographic findings, and they should be referred for further examination. Plasma OCN may interconnect a relationship between postmenopausal status and the low mandibular bone density.

The Relevance of Osteoclastic and Osteoblastic Activity Markers Follow-Up in Patients on Antiresorptive Osteoporosis Treatment

In general, markers of bone formation and markers of bone resorption are changing synergistically, so the monitoring of any osteoclastic and any osteoblastic marker should reflect the rate of bone transformation. The aim of the study is to monitor the bone metabolism markers in postmenopausal women with osteoporosis and osteopenia along with the variations caused by the effects of bisphosphonate therapy. The study involved 55 women of average age of 57.95 years, with osteopenia or osteoporosis. The patients with osteoporosis were treated with bisphosphonates (75 mg once a week); the laboratory tests were performed before the treatment and 6 months later. Patients with osteopenia were evaluated at the first assessment and 6 months later. The tests included bone densitometry, dual-energy X-ray absorptiometry, osteocalcin, alkaline phosphatase, collagen 1 N-terminal pro-peptide (P1NP), and beta C telopeptide of type I collagen (CTX). The mean T-score was -2.80 ± 0.63 before therapy and -2.64 ± 0.45 6 months later (p < 0.001). Women with osteoporosis had elevated levels of osteocalcin and P1NP at the first assessment, whereas the alkaline phosphatase level did not change with the treatment. After the introduction of antiresorptive therapy, the levels of osteocalcin and P1NP significantly decreased (p < 0.001). In the group with osteopenia, the biochemical markers activity were increased in both assessments. In patients with osteoporosis, Beta-CTX was increased in the first evaluation, and decreased after treatment (p = 0.001). The results indicate that the assessment of biochemical markers of bone metabolism show excellent results in the assessment of prognosis, monitoring the course and the response to various treatment regimens of osteoporosis and evince strong correlation with standard densitometry and dual-energy X-ray absorptiometry procedures. P1NP and CTX show better diagnostic applicability compared with osteocalcin and alkaline phosphatase. The analysis of the activity of biochemical markers may obtain early information on the therapeutic response, before definitive assessment by bone density measurements.

ABO Blood Group and Prevalence of Osteoporosis and Osteopenia in the Elderly Population: An Amirkola Health and Ageing Project (AHAP)-Based Study

Osteoporosis is known as a degenerative disease of the skeletal system and its main complication is fracture, which influences quality of life in the elderly. There are 4 major blood groups in humans based on the presence of A and B antigens. According to the investigations, there are reported relations between blood types and some diseases. In this study, the association between the ABO blood group and the prevalence of osteoporosis and osteopenia in an elderly population was investigated. Medical records of 990 elderly people were investigated in a cross-sectional study and the association between their blood group and the incidence of osteoporosis and osteopenia was analyzed using SPSS version 17.0 (SPSS Inc., Chicago, IL, USA). The results showed that ABO blood groups had no association with the prevalence of osteoporosis in both elderly men and women. The association between age and osteoporosis was significant and the association between this disorder and gender was significant too. The results also indicate that there is no association between RH⁺ and RH^- blood types and osteoporosis and osteopenia in both men and women. Based on this finding, it would be reasonable to conduct extensive studies.

Long-Term Effect of Pulsed Nd-YAG Laser Combined with Exercise on Bone Mineral Density in Men with Osteopenia or Osteoporosis: 1 Year of Follow-Up

BACKGROUND

A pulsed Nd-YAG laser is an effective physiotherapy modality used as a class IV high-intensity laser therapy (HILT).

OBJECTIVE

The aim of this study is to investigate the efficacy of HILT alone or combined with exercise (HILT+EX) on bone mineral density (BMD) after 24 weeks and at 1 year of follow-up in men with osteopenia or osteoporosis.

METHODS

One hundred men with osteopenia or osteoporosis (mean age, 53.78 [2.89] years; weight, 80.56 [7.33] kg; height 175 [5.30] cm) participated in the study. The T-scores were ≤-1.5. Patients were randomly assigned to four groups: HILT+EX (group I), placebo laser plus exercise (PL+EX; group II), HILT alone (HILT; group III), and PL (group IV). HILT was applied to the lower back and hip regions. Aerobic, weight-bearing, flexibility, strengthening, and balance exercises were performed three times per week for 24 weeks. The measured outcomes were BMD of the L₂-L₄ spine and total hip. Measurements were taken before and after 24 weeks and at 1 year of follow-up.

RESULTS

Lumbar and total hip BMD significantly increased post-treatment in the HILT+EX and PL+EX groups, but insignificantly in the HILT and PL groups. HILT+EX showed a significantly greater effect than PL+EX did on lumbar BMD, with no significant difference in total hip BMD, after 24 weeks and at follow-up.

CONCLUSIONS

Although HILT alone did not effectively increase lumbar and total hip BMD, HILT combined with exercise was more effective than exercise alone at increasing lumbar BMD after 24 weeks of treatment, with effects lasting up to 1 year.

Efficacy of high intensity laser therapy in the treatment of male with osteopenia or osteoporosis: a randomized placebo-controlled trial

[Purpose] To investigate the effect of high intensity laser therapy, alone or combined with exercise on pain, health related quality of life and fall risk in male with osteopenia or osteoporosis. [Subjects and Methods] 100 male patients with osteopenia or osteoporosis participated in the study. They had T-scores ≤−1.5. Patients were randomly assigned into four groups and treated with laser plus exercise, placebo laser plus exercise, laser alone and placebo laser in groups I, II, III, and IV respectively. Laser was applied to the lower back and hip regions. Exercises included aerobic exercises, weight-bearing, flexibility, and strengthening and balance exercises. Treatment were performed 3 times/week for 12 weeks. The measured outcomes were pain, health related quality of life and fall risk. [Results] All measured outcomes were significantly decreased post-treatment in all treatment groups. Laser plus exercises showed a higher significant effect than exercises with a least significant effect in the laser group in reduction of pain and quality of life. [Conclusion] High intensity laser is an effective modality for male patients with osteopenia or osteoporosis. Laser combined with exercise is more effective than exercises or laser alone in decreasing pain, fall risk an increasing quality of life after 12 weeks of treatment.

Serum levels of phosphorylated heat shock protein 27 (pHSP27) are associated with bone mineral density in pre- & postmenopausal women: A pilot study

BACKGROUND & OBJECTIVES

Phosphorylated heat shock protein 27 (pHSP27) has been implicated in the pathogenesis of osteoporosis. oxidative stress and proinflammatory cytokines, which are known to be involved in aetiology of osteoporosis, can trigger HSP27 phosphorylation. Since pHSP27 is present in circulation, it was hypothesized that serum pHSP27 would be elevated in low bone mineral density (BMD) condition and might serve as an indicator of osteoporosis/osteopenia. Hence, the aim of this study was to examine serum levels of pHSP27 in relation with BMD in pre- and postmenopausal women.

METHODS

Premenopausal (30 to 40 yr) and postmenopausal (50 to 60 yr) women having either low BMD (osteopenia/osteoporosis) or high BMD were selected (n=80) from a prospective cohort (n=200). Serum levels of pHSP27; along with levels of oestradiol, malondialdehyde, total antioxidant capacity, interleukin (IL)-1, IL-6, tumour necrosis factor - alpha, (TNF-α), c-telopeptide fragments of collagen type I (CTX-1) and osteocalcin were estimated.

RESULTS

The serum levels of pHSP27 were significantly elevated in low BMD groups in premenopausal and postmenopausal categories (p<0.05). It also exhibited a significant odds ratio (OR) to differentiate between low and high BMD in both premenopausal (OR=1.734, p=0.013) and postmenopausal (OR=1.463, p=0.042) categories. Additionally, area under the curve to predict low BMD was non-significantly higher for pHSP27 than CTX-1 in premenopausal and postmenopausal categories.

INTERPRETATION & CONCLUSIONS

This study highlights a novel relation between serum pHSP27 and BMD in Indian women however, these findings need to be confirmed in larger studies.

Schisandrae Fructus Reduces Symptoms of 4-Vinylcyclohexene Diepoxide-Induced Ovarian Failure in Mice

Menopause is associated with a decrease in the level of sex hormones such as ovarian estradiol and progesterone and can cause various symptoms such as depression, hot flash, fatigue, heart palpitations, and headache. Furthermore, there is a risk of developing complications such as osteoporosis, cardiovascular diseases, Alzheimer’s disease, and ovarian cancer. Schisandrae Fructus (SF) is widely used in Korean medicine as a cure for such complications. This study was conducted to evaluate the therapeutic effects of SF against menopause symptoms associated with follicle depletion caused by the industrial chemical 4-vinylcyclohexene diepoxide (VCD) in mice. VCD directly targets the preantral follicles. Mice were injected with VCD (160 mg/kg intraperitoneally) daily for 15 days and then with SF dosage 3 times/week for six weeks. To evaluate the effects of SF, body weight, tail skin temperature, uterine weight, lipid profile, and osteocalcin levels were measured. A decrease in body weight and tail skin temperature and an increase in uterine weight were observed upon SF treatment. Moreover, SF treatment significantly decreased total cholesterol, triglyceride, osteocalcin, and low-density lipoprotein levels and low-density/high-density lipoprotein ratio. These results suggest the potential use of SF in the treatment of menopausal symptoms in women.

Differential effects of calcium- and vitamin D-fortified milk with FOS-inulin compared to regular milk, on bone biomarkers in Chinese pre- and postmenopausal women

PURPOSE

To compare the effects of a high-calcium vitamin D-fortified milk with added FOS-inulin versus regular milk on serum parathyroid hormone, and bone turnover markers in premenopausal (Pre-M) and postmenopausal (PM) women over 12 weeks.

METHODS

Premenopausal women (n = 136, mean age 41 (±5) years) and postmenopausal women [n = 121, mean age 59 (±4) years] were recruited, and each age group randomised into two groups to take two glasses per day of control = regular milk (500 mg calcium per day) or intervention (Int) = fortified milk (1000 mg calcium for pre-M women and 1200 mg calcium for PM women, 96 mg magnesium, 2.4 mg zinc, 15 µg vitamin D, 4 g FOS-inulin per day). At baseline, week 4 and week 12 serum minerals and bone biochemical markers were measured and bone density was measured at baseline.

RESULTS

Mean 25-hydroxyvitamin D [25(OH) vitamin D3] levels among groups were between 49 and 65 nmol/L at baseline, and over the 12 weeks of supplementation, the fortified milk improved vitamin D status in both Int groups. CTx-1 and PINP reduced significantly in both Pre-M and PM groups over the 12 weeks, with the changes in CTx-1 being significantly different (P < 0.035) between PM control and PM Int groups at week 12. Parathyroid hormone levels were significantly reduced in all groups over time, except for control PM group where levels increased at 12 weeks.

CONCLUSION

The overall pattern of responses indicates that while both regular milk and fortified milk reduce bone resorption in young and older women, fortified milk is measurably more effective.

Association between serum osteocalcin and insulin resistance in postmenopausal, but not premenopausal, women in Korea

OBJECTIVE

Menopause is known to compound cardiometabolic disease risk factors, and a deeper understanding of the mechanism of this effect is needed. Recently, the osteoblast-derived protein osteocalcin was found to function as a regulator of glucose and fat metabolism. However, there is a lack of studies comparing the extent of association between osteocalcin and glucose metabolism in postmenopausal versus premenopausal women.

METHODS

To examine the relationship between serum osteocalcin and glucose metabolism in premenopausal versus postmenopausal women, we identified well-balanced pairs of premenopausal and postmenopausal women matched on propensity score. The interactions between serum osteocalcin levels and menopause status on fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) and the associations of these parameters with serum osteocalcin levels in premenopausal and postmenopausal women were statistically analyzed.

RESULTS

Among the 61 matched pairs of premenopausal and postmenopausal women, significant interactions of menopause status and serum osteocalcin levels were observed for fasting insulin (P = 0.031) and HOMA-IR (P = 0.019). Furthermore, after logarithmical transformation for each variable, significant relationships between serum osteocalcin levels and fasting insulin (r = -0.307, P = 0.016) and HOMA-IR (r = -0.298, P = 0.019) were found in postmenopausal women, but no significant correlation was seen in premenopausal women (r = 0.002, P = 0.989 and r = 0.062, P = 0.633, respectively).

CONCLUSIONS

Our study shows that the association between serum osteocalcin and insulin resistance varies according to menopause status, and that serum osteocalcin is associated with insulin resistance in postmenopausal women but not in premenopausal women. As postmenopausal women have a higher prevalence of obesity and other cardiac risk factors, the potential endocrine actions of osteocalcin may serve as a marker of metabolism in menopause status. Further studies are needed to define the precise nature of the relationship between osteocalcin and insulin resistance in postmenopausal women.

Poststroke hip fracture: prevalence, clinical characteristics, mineral-bone metabolism, outcomes, and gaps in prevention

Objective. To assess the prevalence, clinical and laboratory characteristics, and short-term outcomes of poststroke hip fracture (HF). Methods. A cross-sectional study of 761 consecutive patients aged ≥60 years (82.3 ± 8.8 years; 75% females) with osteoporotic HF. Results. The prevalence of poststroke HF was 13.1% occurring on average 2.4 years after the stroke. The poststroke group compared to the rest of the cohort had a higher proportion of women, subjects with dementia, history of TIA, hypertension, coronary artery disease, secondary hyperparathyroidism, higher serum vitamin B12 levels (>350 pmol/L), walking aid users, and living in residential care facilities. The majority of poststroke HF patients had vitamin D insufficiency (68%) and excess bone resorption (90%). This group had a 3-fold higher incidence of postoperative myocardial injury and need for institutionalisation. In multivariate analysis, independent indicators of poststroke HF were female sex (OR 3.6), history of TIA (OR 5.2), dementia (OR 4.1), hypertension (OR 3.2), use of walking aid (OR 2.5), and higher vitamin B12 level (OR 2.3). Only 15% of poststroke patients received antiosteoporotic therapy prior to HF. Conclusions. Approximately one in seven HFs occurs in older stroke survivors and are associated with poorer outcomes. Early implementation of fracture prevention strategies is needed.

Association of vitamin D receptor BsmI gene polymorphism with risk of osteoporosis: a meta-analysis of 41 studies

Vitamin D receptor (VDR) BsmI gene polymorphism has been reported to be strongly associated with osteoporosis risk in some studies. However, the results from those studies are still conflicting. We performed a meta-analysis of studies relating the VDR BsmI gene polymorphism to the risk of osteoporosis. The search was performed in the databases of PubMed, Embase, Cochrane Library and CBM-disc (China Biological Medicine Database) as of October 1, 2011, and the eligible investigations were recruited for this meta-analysis. Forty-one investigations were identified for the meta-analysis of association between VDR BsmI gene polymorphism and osteoporosis risk. There lacked an association between VDR BsmI gene polymorphism and osteoporosis risk for overall populations, Caucasians and Asians (overall populations: B vs b: p = 0.65, BB vs (Bb + bb): p = 0.14, bb vs (BB + Bb): p = 0.86; Caucasians: B vs b: p = 0.65, BB vs (Bb + bb): p = 0.38, bb vs (BB + Bb): p = 0.83; Asians: B vs b: p = 0.87, BB vs (Bb + bb): p = 0.62, bb vs (BB + Bb): p = 0.66). In conclusion, VDR BsmI B/b gene polymorphism is not associated with the susceptibility of osteoporosis in overall populations, Caucasians, and Asians.

Association between obesity, metabolic risks and serum osteocalcin level in postmenopausal women

BACKGROUND

Osteocalcin, a marker of bone formation, is also known as a regulator of glucose and fat mass. The purpose of this study was to determine the association between obesity, metabolic risks and serum osteocalcin in postmenopausal women.

METHODS

We selected 214 postmenopausal women and determined serum osteocalcin, fasting plasma glucose (FPG), fasting insulin, high-sensitivity C-reactive protein (hs-CRP), the homeostasis model assessment of insulin resistance (HOMA-IR), lipid profile, and anthropometric values (body mass index [BMI], waist-to-hip ratio [WHR], body fat, and visceral fat area [VFA]).

RESULTS

After adjustment for age and years since menopause, WHR and VFA were negatively correlated with serum osteocalcin, but BMI did not show a significant correlation. Serum osteocalcin was negatively correlated with fasting insulin and HOMA-IR, but FPG, lipid profile, and blood pressure did not show a significant correlation. Based on multiple regression analysis, age and HOMA-IR were the most important predictors of osteocalcin.

CONCLUSION

Our study showed that serum osteocalcin has some significance as an indicator of metabolic risk, including abdominal obesity and insulin resistance. Bone as well as adipose tissue may be an active organ that regulates energy metabolism. A larger study will be needed to clarify the potential of osteocalcin as an indicator of cardiovascular disease.

High-calcium, vitamin D fortified milk is effective in improving bone turnover markers and vitamin D status in healthy postmenopausal Chinese women

BACKGROUND/OBJECTIVES

Risk for developing osteoporosis increases in Asia. The purpose of the study was to evaluate the impact of a high-calcium vitamin D fortified milk (HCM) intervention on parathyroid hormone (PTH) levels, vitamin D status and markers of bone turnover in postmenopausal Chinese women.

SUBJECTS/METHODS

Sixty three women (>55 years) were assigned to receive two servings of either a calcium/vitamin D fortified milk or a control drink for 12 weeks. PTH, serum 25 (OH)D levels, C-telopeptide of type I collagen (CTX) levels and procollagen type I N-terminal propeptide (PINP) were measured at baseline, 2, 8 and 12 weeks of supplementation.

RESULTS

Daily calcium intake at baseline ranged between 260 and 482 mg for the HCM, and 252 and 692 mg for the control group. HCM improved serum 25 (OH)D levels significantly (33.13-39.49 nmol/l), while remaining similar in the control group (29.27-28.21 nmol/l). The difference between the groups were significant at week 2, 8 and 12. The percentage change in PTH levels in the HCM group was significant from week 2 onwards compared to the control drink (P<0.017, P<0.05 and P<0.001 at weeks 2, 8 and 12, respectively). Plasma CTX of the HCM group reduced by 25% between weeks 0 and 2, remaining significantly lower and at similar levels up to week 12. The difference between the HCM and control group for PINP reached significance at weeks 8 (P=0.011) and 12 (P=0.003).

CONCLUSIONS

The HCM intervention significantly improved vitamin D status and reduced bone turnover over 12 weeks in postmenopausal Chinese women.

Mitochondrial DNA copy number in peripheral blood is associated with femoral neck bone mineral density in postmenopausal women

OBJECTIVE

It has been suggested that mitochondrial dysfunction is related to aging and metabolic disorders. Yet there are few studies of the relationship between bone mineral density (BMD) and mitochondrial content in humans. We investigated the relationship between BMD and mitochondrial DNA (mtDNA) copy number in peripheral blood of postmenopausal women.

METHODS

The study included 146 postmenopausal women. Enrolled subjects were taking no medications and had no disorders that altered bone metabolism. We measured BMD using dual-energy x-ray absorptiometry and leukocyte mtDNA copy number using real-time polymerase chain reaction. Anthropometric evaluations and biochemical tests were performed.

RESULTS

Patients with osteopenia or osteoporosis had lower mtDNA copy numbers than normal subjects (p < 0.0001). Femoral neck BMD was negatively correlated with age (r = -0.01, p = 0.04) and with serum levels of adiponectin (r = -0.22, p = 0.01) and osteocalcin (r = -0.31, p = 0.0001). Serum levels of 25-OH vitamin D (r = 0.32, p < 0.0001) and mtDNA copy number (r = 0.36, p < 0.0001) were positively correlated with femoral neck BMD. Multiple regression analysis showed that mtDNA copy number (ß = 0.156, p < 0.001) was an independent factor associated with femoral neck BMD after adjustment for age, body mass index, waist circumference, waist-hip ratio, blood pressure, homeostatic model assessment of insulin resistance, high-sensitivity C-reactive protein, adiponectin, osteocalcin, homocysteine, lipid profiles, 25-OH vitamin D, and regular exercise. mtDNA copy number was not related to lumbar BMD.

CONCLUSION

Low mtDNA content in peripheral blood is related to decreased femoral neck BMD in postmenopausal women. Our findings suggest that mitochondrial dysfunction may be a potential pathophysiologic mechanism of osteoporosis in postmenopausal women.

Oxytocin and bone remodelling: relationships with neuropituitary hormones, bone status and body composition

PURPOSE

There is growing evidence that oxytocin, which regulates appetite, plays a role in bone remodelling and improves osteoporosis. We previously showed a significant decrease in circulating oxytocin levels in postmenopausal osteoporotic women compared to healthy controls. However, factors involved in the pathophysiology of osteoporosis, such as estrogens and leptin, are known to regulate oxytocin secretion. Herein, we evaluated the relationships between oxytocin and other hormonal factors known to regulate bone remodeling and body composition in postmenopausal osteoporotic women, compared to healthy controls.

METHODS

In 20 postmenopausal women with severe osteoporosis compared to 16 healthy controls, we measured serum levels of oxytocin, high sensitive estradiol, testosterone, FSH, LH, SHBG, TSH, osteocalcin, serum type I collagen carboxy-terminal telopeptide, leptin. Bone mineral density and body composition were also measured with DXA.

RESULTS

Osteoporotic women had significantly lower oxytocin, leptin and LH serum levels and higher CTX and SHBG; all other biological parameters were similar in both groups. Fat mass and lean mass were significantly decreased in osteoporotic women. Oxytocin serum levels were significantly correlated to bone mineral density but not to any other measured parameter, including leptin, estradiol and age. In a logistic regression analysis, osteoporosis remained significantly correlated to oxytocin, regardless of age.

CONCLUSIONS

Low oxytocin serum levels appeared to be associated with severe osteoporosis, independently of other factors associated with osteoporosis or known to regulate oxytocin serum levels, such as estradiol or leptin, reinforcing the concept that oxytocin may be involved in the pathophysiology of postmenopausal osteoporosis.