Effects of glucose on in vitro development of osteoblasts and expression of glucose transporter 1

Objective To evaluate the effects of glucose on in vitro development of osteoblasts and expression of glucose transporter 1 (GLUT1).Methods Osteoblasts of new born Sprague-Dawley (SD) rat cranial bones were isolated and cultured in culture media containing normal (5.5 mmol/L) or high (25.5 mmol/L) concentration of glucose.MTT assay was employed to observe osteoblasts proliferation and alizarin red S (ARS) staining was used to detect bone nodule formation.GLUT1 mRNA and protein were examined by RT-PCR and Western blottig.Results High concentration of glucose was shown to significantly promote cellular proliferation on days 3,4 and 5 [ (0.390 0+0.002 4) vs (0.320 0±0.012 7),(0.540 0±0.009 4) vs (0.440 0±0.004 6),(0.720 0±0.001 3) vs (0.600 0±0.006 1 ),all P＜0.05 ] but inhibit cellular mineralization and bone nodule formation when compared with normal concentration.Macroscopic calcified nodules formed earlier in normal concentration group than that in high concentration group (day 9 vs day 14).On the last day of the experiment (day 32),the number of bone nodules in high concentration group was significantly lower (P＜0.05).The level of GLUT1 mRNA and protein in high glucose group increased significantly compared with normal glucose group.Conclusions High concentration of glucose promotes the proliferation but inhibits the mineralization of osteoblasts,which may lead to bone formation disorder.High concentration glucose-induced GLUT 1 change may play an important role in the process of bone formation. Key words: Glucose ;  Osteoblast;  Diabetes ;  Glucose transporter 1 ;  Bone nodule