January - March 2018, Volume 14, Issue 1

Kacso A, Goia-Socol M, Hazi G, Tomoaia G, Kacso IM, Georgescu CE

Effect of Experimental Dysglycemia on Under-Carboxylated Osteocalcin Production in Human Primary Osteoblast-Like Cell Cultures

Acta Endo (Buc) 2018, 14 (1): 11-15
doi: 10.4183/aeb.2018.11

Context. The undercarboxylated form of osteocalcin (ucOC) and osteoprotegerin (OPG) are bonederived molecules involved in the endocrine crosstalk governing the bone, the adipose tissue and the pancreas. In addition, glucocorticoids are major determinants of both insulin resistance and osteoporosis. Objective. We aimed to investigate the response of ucOC and OPG to dysglycemia and/or dexamethasone (DXM) in primary human osteoblastic cell (HOC) cultures. Design and methods. Third-passage sub-confluent primary HOC cultures were treated with glucose: 2.8 mmol/L, 5.6 mmol/L, 11.1 mmol/L and 28 mmol/L, respectively. Alternatively, HOC cultures were subjected to DXM 1 μmol/L. In more complex experiments, HOC cultures were pre-treated with glucose (5.6 mmol/L) with/without insulin (1 pmol/L) followed by DXM (1 μmol/L). 24-hours posttreatment, culture medium ucOC and OPG were measured by ELISA. Results. ucOC production differed significantly (p<0.05) between cell groups, decreasing in a dosedependent manner as glucose concentration in the medium increased. Insulin prevented this effect. OPG levels appeared not to be significantly influenced by the hyperglycemic culture medium and were not related to ucOC concentration (p>0.05). Addition of DXM resulted in significantly lower ucOC concentrations compared to vehicle-treated cells (p<0.05). However, the effect of insulin co-treatment on ucOC was not counteracted by DXM (p<0.05). Conclusions. An obvious alteration of OC production/metabolism was observed as glucose levels changed in the bone microenvironment, to potentially be involved in diabetes-related osteopenia. DXM suppressed ucOC levels however not in insulin-rich environment.

Keywords: human osteoblasts, undercarboxylated osteocalcin, osteoprotegerin, insulin, dexamethasone, osteopenia, diabetes mellitus.

Correspondence: Carmen Emanuela Georgescu MD PHD, “Iuliu Hatieganu” University of Medicine and Pharmacy Cluj-Napoca, Discipline of Endocrinology, 6th Medical Specialties Dept, 44F Eugen Ionesco St, Cluj-Napoca, 400496, Romania, E-mail: c_e_georgescu@yahoo.com