In the Search for Associations between Bone and Fat Tissues in the Control of Glucose Homeostasis: Role of Osteocalcin, Bone Resorption and Leptin, in Normoglycemic Nondiabetic Women

BONANNO MARINA SOLEDAD; MARIANA SEIJO; ZENI CORONEL MAGALÍ; CLARISA MAROTE; ZAGO L; OLIVERI BEATRIZ M; BRITO GRACIELA; ZENI SUSANA NOEMI

NUTRITION & FOOD SCIENCE

Emerald Publishing - UK

Año: 2022

0034-6659

Background: Osteocalcin (OCN) is involved in controlling glucose homeostasis by stimulating insulin (Ins) and adiponectin production and secretion through the undercarboxylated (uc) form of OCN. Through the sympathetic nervous system, leptin inhibits bone formation, increases RANKL production and the resortive activity of osteoclasts, regulating the bioactivation of OCN. Differences in body mass, estrogenic status, vitamin D (VD) and calcium (Ca) nutritional status might affect bone and fat interrelationship. Study aim: The present cross-sectional study explores this relationship in normoglucemic non-diabetic pre (nM) and postmenopausal (PM) women. Methods: Women (n=484) that met the inclusion criteria were included in the study. Results: When only normal-weight women, were evaluated, total (t) OCN and ucOCN levels were 17.6±9.5 ng/mL and 1.0±0.8 ng/mL (0.15-4.95 ng/mL) in nM, and 20.6±8.9 ng/mL and 1.6±1.1 ng/mL (0.24-3.81 ng/mL) in PM women. In line with the fact that most circulating protein factors associated with regulatory functions are inactive, the mean percentage of ucOCN/tONC was 5% and 8% for nM and PM. When all the studied women having different BMI were included in the analysis, the mean values for tOCN showed a slight increase (26.4±9.5 ng/mL and 27.1±9.8 ng/mL in nM and PM, respectively), while ucOCN increased significantly (2.5±1.9 ng/mL and 2.9±1.7 ng/mL in nM and PM, respectively). As a result ucOCN/tOCN showed a significant increase with obesity, similar to that observed in Ins resistance, suggesting that fat mass may induce not only Ins resistance but also a certain degree of resistance to the hormonal form of OCN. Conclusion: As obesity increases, higher circulating ucOCN related to tOCN levels are necessary to maintain glucose homeostasis. Then, obesity appears to induce a certain degree of resistance to OCN endocrine action. In ucOCN action the adequacy of Ca and VD nutritional status plays an important role.