ABSTRACT
BACKGROUND: Recent study showed that osteocalcin may elevate Insulin secretion and sensitivity, prevent the fat accumulation, play a role in the metablism of glucose and lipid. Undercarboxylated osteocalcin works as the main role. OBJECTIVE: To investigate the effect of different concentrations of glucose on osteoblast undercarboxylated osteocalcin. METHODS: The rib trabeculae were resected and broken, trypsinizated and washed completely by PBS. Bone surface and non-adhesive floating cells in cleaning fluid were observed with inverted microscope. Rib trabeculae was washed by DMEM culture medium once, and cultured in culture bottle. The culture liquid was replaced by new one once a week. The osteoblast was moved from the scledte a week later. The cells were fused monolayer and could be subcultured 4 to 6 weeks later. The active second or third generation cells were inoculated to 6-pore plate forming 5 groups. Osteoblast were stimulated by 5.6 mmol/L., 7.6 mmol/L, 9.6 mmol/L, 12.6 mmol/L, 20.6 mmol/L glucose medium respectively after the 80% cells were fused, the vitamin K_2 was added into the culture liquid until the concentration of it to be 10~(-5) mol/L. Supernatant was collected after half hour culturing, the undercarboxylated osteocalcin level were detected with RIA test kit, and corrected it as the total the undercarboxylated osteccalcin, calculated the carboxylated incomplete osteocalcin rate. RESULTS AND CONCLUSION: The rate of ostecblast carboxylated incomplete osteocalcin was different under different concentration glucose. The rate of 7.6 mmol/L, 9.6 mmol/L, 20.6 mmol/L concentration glucose groups were higher than that of 5.6 mmol/L glucose group [(0.27±0.02)%, (0.29±0.04)%, (0.12±0.02)%, P < 0.05]. It is indicated that osteoblast could sense the change of glucose concentration by regulating the secretion of the undercarboxylated osteocalcin between the concentration of 5.6mmol/L to 9.6mmol/L, while the carboxylated incomplete osteocalcin decreased as the concentration of glucose increased.