Serum osteocalcin is related to abdominal obesity in Korean obese and overweight men

A cross-sectional study on the use of big data for the past H1N1 influenza epidemic in obesity after COVID-19: Focused on the body slimming cream and leptin via DTC gene test

BACKGROUND

Based on the big data of 2010, 2011, and 2012, when H1N1 influenza was prevalent around the world in the past, this study investigated the obesity rate, weight change, and dietary methods of Korean dieters based on the historical situation of the past H1N1 influenza epidemic in Republic of Korea. This is intended to be the data for utilizing the prognostic evaluation of coronavirus disease-19 (COVID-19).

OBJECTIVE

After COVID-19, research on obesity should be conducted systematically, and to prevent obesity, nutrition education, customized inner beauty & cosmetics, and the development of body slimming cream and leptin for proper diet should be done at the national level. This study was conducted to investigate the relationship between methods of weight control, generation, and gender, which have not yet been evaluated in the Korean adult population.

METHODS

The cross-sectional study was comprised of 25 534 Korean who participated in the Fifth Korean National Health and Nutrition Examination Survey (KNHNES) conducted in 2010, 2011, and 2012.

RESULTS

A 17 876 of the 19 375 respondents 20 years of age or older in the KNHNES answered about diet method. Two thousand and fifty-seven (15.63%) men and 4134 (25.77%) women thought of themselves as fat. However, 11 973 people (66.96%) did not change weight in the past year, 2536 people (14.19%) had increase in weight, and 3.164 (17.70%) reduced weight. A total of 7176 people (48.11%) indicated that they attempted to reduce weight through exercising, while 5553 people (37.23%) did so through reduced food intake.

CONCLUSIONS

This study was based on big data at the time of the H1N1 influenza epidemic in Korean population. The results of the present study will be helpful in the development of the body slimming cream and leptin via direct to consumer (DTC) gene test (GT) due to the rapid increase in obesity due to COVID-19 pandemic.

The Role of Exercise in the Interplay between Myokines, Hepatokines, Osteokines, Adipokines, and Modulation of Inflammation for Energy Substrate Redistribution and Fat Mass Loss: A Review

Exercise is an effective strategy for preventing and treating obesity and its related cardiometabolic disorders, resulting in significant loss of body fat mass, white adipose tissue browning, redistribution of energy substrates, optimization of global energy expenditure, enhancement of hypothalamic circuits that control appetite-satiety and energy expenditure, and decreased systemic inflammation and insulin resistance. Novel exercise-inducible soluble factors, including myokines, hepatokines, and osteokines, and immune cytokines and adipokines are hypothesized to play an important role in the body's response to exercise. To our knowledge, no review has provided a comprehensive integrative overview of these novel molecular players and the mechanisms involved in the redistribution of metabolic fuel during and after exercise, the loss of weight and fat mass, and reduced inflammation. In this review, we explain the potential role of these exercise-inducible factors, namely myokines, such as irisin, IL-6, IL-15, METRNL, BAIBA, and myostatin, and hepatokines, in particular selenoprotein P, fetuin A, FGF21, ANGPTL4, and follistatin. We also describe the function of osteokines, specifically osteocalcin, and of adipokines such as leptin, adiponectin, and resistin. We also emphasize an integrative overview of the pleiotropic mechanisms, the metabolic pathways, and the inter-organ crosstalk involved in energy expenditure, fat mass loss, reduced inflammation, and healthy weight induced by exercise.

Metabolic and Endocrine Consequences of Bariatric Surgery

Obesity is one of the most serious worldwide epidemics of the twenty-first century according to the World Health Organization. Frequently associated with a number of comorbidities, obesity threatens and compromises individual health and quality of life. Bariatric surgery (BS) has been demonstrated to be an effective treatment to achieve not only sustained weight loss but also significant metabolic improvement that goes beyond mere weight loss. The beneficial effects of BS on metabolic traits are so widely recognized that some authors have proposed BS as metabolic surgery that could be prescribed even for moderate obesity. However, most of the BS procedures imply malabsorption and/or gastric acid reduction which lead to nutrient deficiency and, consequently, further complications could be developed in the long term. In fact, BS not only affects metabolic homeostasis but also has pronounced effects on endocrine systems other than those exclusively involved in metabolic function. The somatotropic, corticotropic, and gonadal axes as well as bone health have also been shown to be affected by the various BS procedures. Accordingly, further consequences and complications of BS in the long term in systems other than metabolic system need to be addressed in large cohorts, taking into account each bariatric procedure before making generalized recommendations for BS. In this review, current data regarding these issues are summarized, paying special attention to the somatotropic, corticotropic, gonadal axes, and bone post-operative health.

Osteocalcin improves insulin resistance and inflammation in obese mice: Participation of white adipose tissue and bone

AIMS/HYPOTHESIS

The discovery of osteocalcin, a protein synthetized by osteoblasts, as a hormone that has positive effects on insulin resistance, contributed to support the concept of bone as an endocrine organ. However, very little is known about the molecular pathways involved in osteocalcin improved-insulin resistance. The present study aimed to investigate the mechanisms of action of osteocalcin on insulin resistance and inflammation in obese mice and 3T3-L1 adipocytes.

METHODS AND RESULTS

Lean control, saline-treated obese and uncarboxylated osteocalcin (uOC)-treated obese mice were subjected to insulin tolerance test in vivo. Blood was collect for biochemical/metabolic profile analysis; and, skeletal muscle, white adipose tissue (WAT) and bone were collected for protein (Western blotting) and mRNA (RT-qPCR) analysis. uOC effects on insulin resistance and inflammation were also investigated in 3T3-L1 adipocytes challenged with tumor necrosis factor. Osteocalcin treatment improved in vivo insulin resistance in obese mice. In WAT, osteocalcin had positive effects such as (1) WAT weight reduction; (2) upregulation of glucose transporter (GLUT) 4 protein and its mRNA (Slc2a4); (3) improved insulin-induced AKT phosphorylation; (4) downregulation of several genes involved in inflammation and inflammassome transcriptional machinery, and (5) reduction of the density of macrophage in crown-like structures (histomorphometrical analysis). Notably, in 3T3-L1 adipocytes, osteocalcin restored Slc2a4/GLUT4 content and reduced the expression of inflammatory genes after TNF-a challenge; moreover, osteocalcin treatment increased AKT phosphorylation induced by insulin. Finally, it was observed that in bone, osteocalcin improves insulin resistance by increasing insulin-induced AKT phosphorylation and reducing the expression of genes involved in bone insulin resistance, resulting in increased secretion of uncarboxylated osteocalcin in circulation.

CONCLUSION

We provided some mechanisms of action for osteocalcin in the amelioration of insulin resistance in obesity: in WAT, osteocalcin improves insulin resistance by decreasing inflammation, and increasing insulin signaling and the expression of Slc2a4/GLUT4; and, in bone, osteocalcin increases the secretion of uncarboxylated osteocalcin by improving insulin resistance.

Association between serum osteocalcin and body mass index: a systematic review and meta-analysis

PURPOSE

Osteocalcin is considered as a bone-derived hormone affecting on the body fat distribution and body mass index. Several cross-sectional studies have investigated the association between serum osteocalcin and body mass index. The aim of this study was to summarize the evidence on the relationship between serum osteocalcin and body mass index.

METHODS

We conducted a complete search up to November 2016 in PubMed and SCOPUS and reviewed reference list of all relevant articles and reviews. The DerSimonian-Laird method were used to pool effect sizes of eligible studies. The potential sources of heterogeneity were assessed using the standard χ ² test.To find possible the sources of between-study heterogeneity, we carried out subgroup analyses based on sex, and type of study population.

RESULTS

There was a significant inverse association in the overall result of this study between serum osteocalcin levels and BMI(r = -0.161; 95% CI: -0.197, -0.124, p < 0.000). In the subgroup analysis to find the sources of significant heterogeneity between-study, we observed that the type of the study population may be the source of between-study heterogeneity and the most correlation was seen in metabolic syndrome studies (r = -0.265; p = 0.000).

CONCLUSION

Findings from the available data indicated an overall significant inverse association between serum osteocalcin and body mass index. Further studies based on the type of study population are needed to better clarify these associations.

Osteocalcin as a potential risk biomarker for cardiovascular and metabolic diseases

Clear evidence supports a role for circulating and locally-produced osteocalcin (OC) in the pathophysiology of cardiovascular (CV) lesions and CV risk, also in combination with metabolic changes, including type 2 diabetes mellitus (T2DM). Reduced plasma OC levels are associated with greater incidence of pathological CV changes, like arterial and valvular calcification, coronary and carotid atherosclerosis and increased carotid intima-media thickness. The actual relationship between OC levels and incidence of major CV events is, however, still unclear. Moreover, reduced circulating OC levels have been mostly associated with insulin resistance, metabolic syndrome or T2DM, indicating relevant OC actions on pancreatic β-cells and insulin secretion and activity. Based on these observations, this review article will attempt to summarize the current evidence on the potential usefulness of circulating OC as a biomarker for CV and metabolic risk, also evaluating the currently open issues in this area of research.

Undercarboxylated osteocalcin reverts insulin resistance induced by endoplasmic reticulum stress in human umbilical vein endothelial cells

Osteocalcin has been considered to be an important regulator of energy metabolism in type 2 diabetes mellitus (T2DM). However, the mechanism underlying the involvement of uncarboxylated osteocalcin in the vascular complications of T2DM is not fully understood. In the present study, we analyzed the potential correlations between uncarboxylated osteocalcin and macro- or microangiopathic complications in subjects with T2DM and tested the impact of uncarboxylated osteocalcin on insulin resistance in human umbilical vein endothelial cells (HUVECs). The results showed that the serum levels of uncarboxylated osteocalcin were lower in subjects with vascular complications of T2DM. Univariate correlation analyses revealed negative correlations between uncarboxylated osteocalcin and waist-to-hip ratio, HbA1c, and HOMA-IR. In in vitro experiments, insulin resistance was induced by applying tunicamycin to HUVECs. Uncarboxylated osteocalcin not only markedly reduced the phosphorylations of PERK and eIF2α, but also elevated the phosphorylations of IRS-1 and Akt, resulting in improvement of insulin signal transduction via PI3K/Akt/NF-κB signaling in HUVECs. Therefore, there is a possible relationship between uncarboxylated osteocalcin and the vascular complications of T2DM. Uncarboxylated osteocalcin partially improves insulin signal transduction via PI3K/Akt/NF-κB signaling in tunicamycin-induced HUVECs, suggesting osteocalcin as a potential treatment for the vascular complications of T2DM.

Association of Serum Osteocalcin with Insulin Resistance and Coronary Atherosclerosis

Background

To determine the associations between serum osteocalcin level and insulin resistance, coronary atherosclerosis by using dual-source coronary computed tomography angiography.

Methods

A total of 98 subjects (24 men and 74 women) were selected for this retrospective cross-sectional study who voluntarily visited a health examination center for routine health check-up including the blood test for serum osteocalcin level and coronary computed tomography angiography. Multiple regression analysis was used to determine which variables were independently related to osteocalcin levels and coronary atherosclerosis.

Results

Stepwise multiple regression analysis adjusted for age, sex, menopausal status, body mass index, serum alkaline phosphatase, serum calcium and phosphate showed that osteocalcin negatively correlated with serum glucose (β=-0.145, P=0.001) and homeostasis model assessment of insulin resistance (HOMA-IR) index (β=-1.794, P=0.027) independently. The age, serum glucose, smoking status but not osteocalcin level were independent risk factors for coronary atherosclerosis by use of multiple logistic regression analysis after controlling for other variables.

Conclusions

Serum osteocalcin level was inversely associated with fasting glucose level and insulin resistance measured by HOMA-IR, suggesting that osteocalcin is important for glucose metabolism. However, in this study, no significant difference was observed in the serum osteocalcin level according to the presence of coronary atherosclerotic plaques.

Association between osteocalcin and glucose metabolism: a meta-analysis

This meta-analysis aimed to investigate the associations between osteocalcin (Ocn) and fasting plasma glucose (FPG) and glycated hemoglobin A1c (HbA1c). It was revealed that both total Ocn and undercarboxylated Ocn (unOcn) were negatively related with FPG and HbA1c, and the association of unOcn with FPG was more pronounced in men.

INTRODUCTION

The aim of this study was to investigate the strength of associations between Ocn and FPG and HbA1c using a meta-analysis approach.

METHODS

A search was carried out using the databases of PubMed, ISI Web of Science, and the Cochrane library from 2007 to 2014 to identify related studies. A pooled effect size with 95 % confidence intervals (CI) was derived.

RESULTS

The meta-analysis included 39 studies involving 23,381 participants. The overall correlation was -0.16 (95 % CI, -0.19 to -0.14) between total Ocn (tOcn) and FPG and -0.15 (95 % CI, -0.20 to -0.11) between undercarboxylated Ocn (unOcn) and FPG. In the analysis of the association between Ocn and HbA1c, the pooled correlation was -0.16 (95 % CI, -0.18 to -0.14) for tOcn and -0.16 (95 % CI, -0.23 to -0.08) for unOcn. The magnitude of the correlation between unOcn and FPG is significantly higher in men than in women (r = -0.18, 95 % CI, -0.21 to -0.14; r = -0.09, 95 % CI, -0. 13 to -0.05, respectively; P for interaction < 0.05). Similar trend was also found between unOcn and HbA1c but without significance (for men, r = -0.19, 95 % CI, -0.24 to -0.14; for women, r = -0.09, 95 % CI, -0.22 to 0.04, respectively; P for interaction > 0.05). No indication of significant publication bias was found in any method.

CONCLUSIONS

This meta-analysis demonstrated that both unOcn and tOcn were similarly and negatively correlated with FPG and HbA1c in humans. The negative correlations between unOcn and glucose metabolism appear to be more pronounced in men than in women.

Coronary artery calcification is associated with high serum concentration of undercarboxylated osteocalcin in asymptomatic Korean men

CONTEXT

Osteocalcin is associated with energy metabolism and atherosclerosis, besides bone metabolism. However, the association between osteocalcin or its undercarboxylated form (ucOC) and coronary artery calcification is controversial.

OBJECTIVE

To evaluate the relationship between coronary artery calcium score (CACS) and the concentration of serum osteocalcin and ucOC.

DESIGN

Cross-sectional.

PATIENTS

A total of 162 subjects (114 men and 48 women) with no angina symptom.

MEASUREMENTS

Serum analyses included glucose, insulin and lipid profiles as well as osteocalcin and ucOC. Bone mineral density (BMD) was measured by dual X-ray absorptiometry. CACS was measured using multidetector computed tomography and categorized into CACS = 0 and CACS > 0.

RESULTS

The mean osteocalcin concentration in men was 15·6 ± 4·2 for CACS = 0 group and 14·1 ± 4·0 for CACS > 0 group, respectively (P = 0·050). In women, the osteocalcin concentration, ucOC concentration and ucOC to osteocalcin ratio (OCR) were not different between the CACS groups. However, the concentrations of osteocalcin and ucOC were significantly lower in women with hypertension or diabetes than those without, respectively. In the multivariate logistic regression models adjusted for medical history, body mass index, lipid profiles, insulin resistance and BMD in men, the higher concentration of ucOC and higher OCR showed significant association with coronary calcification (CACS > 0).

CONCLUSION

Higher ucOC concentration was associated with coronary artery calcification independent of conventional cardiovascular risk factors and BMD in men.

Association between serum osteocalcin level and visceral obesity in Chinese postmenopausal women

BACKGROUND

A low serum osteocalcin level, visceral obesity and postmenopausal status are recognized risk factors for cardiovascular disease.

OBJECTIVE

We investigated the relationship between the serum osteocalcin level and visceral fat content in a population of Chinese postmenopausal women.

DESIGN AND PATIENTS

In total, 1481 postmenopausal women (mean age ± standard deviation, 57·1 ± 4·8 years) were selected from the Shanghai Obesity Study.

MEASUREMENTS

Abdominal fat accumulation was quantified using magnetic resonance imaging. Subjects with a visceral fat area (VFA) of ≥80 cm(2) were classified as abdominally obese. The total serum osteocalcin level was measured by electrochemiluminescence immunoassay.

RESULTS

The median serum osteocalcin level was 20·66 μg/l (interquartile range, 16·88-25·42 μg/l). The overall prevalence of abdominal obesity was 49·1% (n = 727). Abdominally obese subjects had lower serum osteocalcin levels than did nonabdominally obese subjects [19·14 (16·02-23·82) vs 21·97 (18·14-26·77) μg/l, respectively; P < 0·001]. Partial correlation analysis showed that the serum osteocalcin level was still negatively correlated with VFA after adjusting for age, years since menopause and body mass index (P < 0·01). Moreover, VFA was independently associated with the serum osteocalcin level after adjustment for confounding factors (P < 0·05). A low serum osteocalcin level was an independent risk factor for abdominal obesity (odds ratio, 0·972; 95% confidence interval, 0·953-0·991; P = 0·004).

CONCLUSION

The serum osteocalcin level was inversely correlated with the visceral fat content in these Chinese postmenopausal women.

Reduced serum total osteocalcin is associated with central obesity in Korean children

BACKGROUND

Recently, osteocalcin (OC), an osteoblast-derived hormone, has been suggested as a new link between obesity and insulin resistance in humans. However, few studies regarding the relationship between OC and obesity in Asian children have been published. We investigated the association of OC with adiposity, insulin resistance and metabolic syndrome (MetS) in Korean children.

METHODS

Two hundred and nine (100 boys, 109 girls) children (age: 9.78 ± 1.05 years, body mass index (BMI): 22.27 ± 5.34 kg/m(2)) participated in this cross-sectional study. Anthropometric parameters, insulin resistance, lipid profiles, total OC, and an inflammatory marker, C-reactive protein (CRP), were measured. MetS phenotype was also determined.

RESULTS

Serum total OC levels were significantly lower in overweight or obese children (76.96 ± 27.08 ng/ml vs. 66.91 ± 21.39 ng/ml, p = 0.020) and it was negatively associated with body fat after controlling for age, gender and BMI. Serum total OC concentrations were significantly lower in participants with central obesity or at least two components of MetS driven by waist circumference than they were in those with none. Stepwise linear regression results also showed that serum total OC was partially explained by age, gender, waist-to-hip ratio, and fasting glucose.

CONCLUSIONS

This study supported a negative association between serum total OC and adiposity in children. OC may be associated with childhood central obesity; however, further research using more accurate measurements is needed to identify the association between these variables.

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.

Role of metabolic factors in the association between osteocalcin and testosterone in Chinese men

OBJECTIVE

Osteocalcin can regulate energy metabolism and increase testosterone production. Although previous studies have shown the positive association between osteocalcin and testosterone, the effect of metabolic factors in the association is unclear.

DESIGN AND SETTING

Osteocalcin, testosterone, and metabolic factors were accessed in 2400 men aged 20 to 69 years, who participated in the population-based Fangchenggang Area Male Health and Examination Survey in Guangxi province of China from September 2009 to December 2009.

MAIN OUTCOME MEASURES

Metabolic syndrome was defined based on the updated report of National Cholesterol Education Program Adult Treatment Panel III criteria. Serum total osteocalcin, total testosterone (TT), and sex hormone binding globulin (SHBG) were measured, whereas free testosterone (FT) and bioavailable testosterone (BT) were calculated based on Vermeulen's formula. The multivariable linear regression analysis was used.

RESULTS

Osteocalcin was positively associated with TT, FT, and BT in the unadjusted model (all P < .001). After adjusting for age, the positive association between osteocalcin and TT remained statistically significant (β = .17, 95% confidence interval = 0.14-0.20) and was not attenuated in each MetS subgroup including hypertriglyceridemia, hyperglycemia, elevated blood pressure, and low high-density lipoprotein cholesterol, while in the group of central obesity (waist circumstance ≥90 cm), the association appeared significantly stronger (β = 0.21, 95% confidence interval = 0.12-0.30). After further adjusting for SHBG, osteocalcin was positively associated with TT, FT, and BT in men with central obesity or men with any two MetS components (all P < .05).

CONCLUSIONS

Serum total osteocalcin is positively associated with testosterone, which is probably modified by SHBG and central obesity.

Osteocalcin reverses endoplasmic reticulum stress and improves impaired insulin sensitivity secondary to diet-induced obesity through nuclear factor-κB signaling pathway

Osteocalcin, a synthetic osteoblast-specific protein, has recently emerged as an important regulator of energy metabolism, but the underlying mechanisms are not fully understood. In the present study, mice fed a high-fat diet and receiving osteocalcin showed reduced body weight gain, less fat pad gain, and improved insulin sensitivity as well as increased energy expenditure compared with mice fed a high-fat diet and receiving vehicle. Meanwhile, increased endoplasmic reticulum (ER) stress, defective insulin signaling, and mitochondrial dysfunction induced by obesity were also effectively alleviated by treatment with osteocalcin. Consistent with these findings, the addition of osteocalcin to the culture medium of 3T3-L1 adipocytes, Fao liver cells, and L6 muscle cells markedly reduced ER stress and restored insulin sensitivity. These effects were nullified by blockade of nuclear factor-κB (NF-κB) or phosphatidylinositol 3-kinase but not by U0126, a mitogen-activated protein kinase inhibitor, indicating the causative role of phosphatidylinositol 3-kinase/NF-κB in action of osteocalcin. In addition, the reversal effects of osteocalcin in cells deficient in X-box-binding protein-1, a transcription factor that modulates ER stress response, further confirmed its protective role against ER stress and insulin resistance. Our findings suggest that osteocalcin attenuates ER stress and rescues impaired insulin sensitivity in insulin resistance via the NF-κB signaling pathway, which may offer novel opportunities for treatment of obesity and diabetes.

Serum under-carboxylated osteocalcin levels in women with polycystic ovary syndrome: weight-dependent relationships with endocrine and metabolic traits

Background

Under-carboxylated osteocalcin (ucOC), the precursor substrate of bone biomarker OC is a potent regulator of energy metabolism by promoting insulin production and adiponectin synthesis and decreasing fat stores. The aim of the present study was to point out the potential role of ucOC in the physiopathology of polycystic ovary syndrome (PCOS), a common disorder defined by the constellation of anovulation, insulinresistance, hyperinsulinemia, obesity and androgen excess.

Methods

In this prospective case–control investigation, 78 young premenopausal women, i.e. 52 PCOS patients and 26 age- and body mass index (BMI)-matched healthy controls, were successively enrolled. Recruitment of PCOS patients was performed according to Androgen Excess-Polycystic Ovary Syndrome (AE-PCOS) Society 2006 criteria. All study participants were subjected to clinical examination, whole-body composition assessment and measurements of serum ucOC, OC (1-49), glucose and lipids, insulin, total testosterone (TT), estradiol, sex-hormone binding globulin (SHBG), high-sensitivity C-reactive protein (Hs-CRP) and β-CrossLaps.

Results

BMI-stratified multivariate analysis revealed significantly higher ucOC levels in PCOS vs. controls in lean (p = 0.001) but not overweight and obese study participants (p = 0.456). Notably, a positive correlation between ucOC and TT (p = 0.018), calculated free testosterone (cFT, p = 0.028) and serum insulin (p = 0.036), respectively, was found to be confined to the lean analysis subgroup. Furthermore, in stepwise multiple regression models, β-CrossLaps and cFT were able to predict 46.71% of serum ucOC variability. (1-43/49)OC failed to be significantly associated to any PCOS trait.

Conclusions

Circulating ucOC concentration is related to key endocrine PCOS characteristics in a weight-dependent manner. Within the bone-pancreas loop, high ucOC may favor insulin release in lean hyperandrogenic women to compensate for impaired insulin sensitivity.

Association between Osteocalcin, Metabolic Syndrome, and Cardiovascular Risk Factors: Role of Total and Undercarboxylated Osteocalcin in Patients with Type 2 Diabetes

Studies have demonstrated that total osteocalcin (TOC) is associated with metabolic syndrome (MetS) and therefore might influence the risk of cardiovascular disease in humans. Undercarboxylated osteocalcin (uOC) regulates insulin secretion and sensitivity in mice, but its relation to MetS in humans is unclear. We aimed to determine whether uOC is related to MetS and/or its individual components and other cardiovascular risk factors in patients with type 2 diabetes mellitus (T2DM), and whether TOC and uOC have utility in predicting the cardiovascular risk. We studied 203 T2DM patients with and without MetS. MetS was defined based on the NCEP-ATP III criteria. A correlation analysis was performed between the three outcome variables: (i) TOC, (ii) uOC, and (iii) carboxylated osteocalcin (cOC) and MetS components and other cardiovascular risk factors. Both TOC and uOC were significantly lower in patients with MetS compared to those without MetS, independent of body mass index. In patients with MetS, uOC was significantly and positively correlated with HDL cholesterol, while TOC was significantly and negatively correlated with serum triglycerides. We report for the first time that uOC is related to lipid indices in patients with T2DM. Further studies are necessary to determine whether uOC can be utilized for cardiovascular risk assessments in these patients.

Significant association between body composition phenotypes and the osteocalcin genomic region in normative human population

Osteocalcin, a major inorganic component of bone matrix and marker of bone formation, is also involved in regulation of glucose and fat mass metabolism. However, much uncertainty remains about whether the above effect on fat mass has a genetic component. Our main aim was to test whether a variation of body composition phenotypes is associated with BGLAP genomic region variants. To achieve this aim, we used an ethnically homogeneous discovery sample of 230 families consisting of 1112 apparently healthy individuals (561 males and 551 females) of European origin. We conducted association analysis between six SNPs and five obesity-related phenotypes: plasma levels of leptin, anthropometrical fat mass (FM), principal component scores of eight skinfold (SK_PC) and nine circumference (CR_PC) measurements, and body mass index (BMI). Two powerful and robust tools were applied: the pedigree disequilibrium test and variance component models, taking into account both familial and genetic effects. Significant association results were observed for all phenotypes. The most significant results were observed between the haplotype composed of three SNPs (rs2758605-rs1543294-rs2241106) and BMI (p=8.07(-7)), and CR_PC (p=5.29(-5)). The association with BMI was tested and confirmed in our replication study, including 2244 unrelated adult US Caucasians, who were previously assessed for whole genome SNP data. In addition, we obtained an evidence of potential non-additive interactions between the above three SNPs concerning their association with BMI. Bioinformatics sources suggest that the aforementioned interaction could originate from different genetic loci in this region; however, ascertaining the exact circumstances requires a detailed molecular-genetic study.

Intermittent injections of osteocalcin improve glucose metabolism and prevent type 2 diabetes in mice

The uncarboxylated form of the osteoblast-specific secreted molecule osteocalcin is a hormone favoring glucose handling and increasing energy expenditure. As a result, the absence of osteocalcin leads to glucose intolerance in mice, while genetically modified mice with an increase in uncarboxylated osteocalcin are protected from type 2 diabetes and obesity. Here, we tested in the mouse the therapeutic potential of intermittent administration of osteocalcin. We found that daily injections of osteocalcin at either 3 or 30 ng/g/day significantly improved glucose tolerance and insulin sensitivity in mice fed a normal diet. This was attributable, in part, to an increase in both β-cell mass and insulin secretion. When mice were fed a high-fat diet (HFD), daily injections of osteocalcin partially restored insulin sensitivity and glucose tolerance. Moreover, mice treated with intermittent osteocalcin injections displayed additional mitochondria in their skeletal muscle, had increased energy expenditure and were protected from diet-induced obesity. Finally, the hepatic steatosis induced by the HFD was completely rescued in mice receiving osteocalcin daily. Overall, these results provide evidence that daily injections of osteocalcin can improve glucose handling and prevent the development of type 2 diabetes.

Androgens modulate osteocalcin release by human visceral adipose tissue

OBJECTIVE

Androgens inhibit adipogenic differentiation through an androgen receptor (AR)-mediated pathway, increase lipolysis and reduce lipid accumulation in adipocytes. Undercarboxylated osteocalcin (ucOCN) regulates insulin and adiponectin secretion and is released by adipose tissue (AT). Our objective was to investigate, ex vivo and in vivo, the role of androgens on osteocalcin (OCN) modulation in human AT. DesiGN, PATIENTS, SETTING: Omental AT (OAT) for in vitro study and blood samples from 91 male patients of Padova University Hospital were used.

MEASUREMENTS

Omental AT was treated with dihydrotestosterone (DHT) in presence and in absence of flutamide. cOCN and ucOCN release by AT in a simple growth medium was evaluated by ELISA. OCN, both undercarboxylated (ucOCN) and carboxylated (cOCN) forms, was measured in serum by ELISA.

RESULTS

After 24-h DHT stimulation, the release of both cOCN and ucOCN by OAT was statistically increased (P < 0·05). Co-incubation with flutamide blunted OCN production. Overweight and obese patients had lower total and free testosterone (T), associated with lower ucOCN and ucOCN/OCN ratio. Free T was negatively correlated to BMI (ρ = -0·706, P < 0·05) and positively correlated to ucOCN/OCN ratio (ρ = 0·223, P < 0·05).

CONCLUSIONS

Our data suggest that androgens modulate OCN release by OAT in vitro. In addition to the anti-adipogenic role of androgens, they support a novel mechanism by which androgens could exert a protective effect in energy metabolism. This hypothesis appears even more significant considering that sexual hormones' levels are greatly altered in obesity and that AT is both highly involved in their clearance and able to produce OCN.