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

MARIANA SEIJO; ZAGO LILIANA; ZENI SUSANA N.; BONANNO MARINA SOLEDAD; CLARISA MAROTE; BRITO GRACIELA; ZENI CORONEL MAGALÍ; OLIVERI BEATRIZ

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 under-carboxylated (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 and, 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 normo-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 insulin resistence, suggesting that fat mass may induce not only insulin resistance but also a certain degree of resistance to the hormonal form of OCN. Conclusion: because of the increase in fat mass, a higher circulation of the under-carboxylated form related to the total amount of OCN may be necessary to maintain glucose homeostasis.