| To study the effect of 1α,25-dihydroxyvitamin D3 or/and NIF on the proliferation, alkaline phosphatase and osteocalcin of osteoblasts, osteoblasts were isolated from SD rat cranial bones and cultured in vitro. The results provided rationale for clinical application.1 Effects of 1α,25-dihydroxyvitamin D3 on osteocalcin of osteoblasts cultured in vitroTo obtain osteoblasts, cranial bones were harvested from SD rat and digested by trypsin and collagenase. In order to observe the effects of 1α,25-dihydroxyvitamin D3 on osteocalcin of osteoblasts cultured in vitro, diffierent concentration of 1α,25-dihydroxyvitamin D3 (0, 10-11, 10-9, 10-7 mol/L) were added to the culture after 80% cell fusion. After 24, 48, 72 h, the osteocalcin of osteoblasts was measured by ELISA kit. We found that all different concentrations of 1α,25-dihydroxyvitamin D3 promoted the secretion of the osteocalcin at all the time dose-dependently. In conclusion, 1α,25-dihydroxyvitamin D3 can induce osteoblasts entering into mineralization period.2 Effects of 1α,25-dihydroxyvitamin D3 on the proliferation and differentiation of osteoblasts cultured in vitro and its mechanismsIn order to observe the effects of 1α,25-dihydroxyvitamin D3 and/or NIF on proliferation and differentiation of osteoblasts cultured in vitro, different concentrations of 1α,25-dihydroxyvitamin D3 or/and NIF were added into the culture after 80% cell fusion. After 24, 48, 72 h, the proliferation and the activity of alkaline phosphatase (ALP) of OB were observed. We found that the high concentration of 1α,25-dihydroxyvitamin D3 (10-9, 10-7 mol/L) inhibited the proliferation of osteoblasts significantly or very significantly (P<0.05或P<0.01), while the low concentration of 1α,25-dihydroxyvitamin D3 (10-11 mol/L) had no effect. NIF (10-8 mol/L) could inhibit the proliferation of osteoblasts by itself. There was no difference between the group of 1α,25-dihydroxyvitamin D3 plus NIF group and the control group. At 24,48 h, compared with the 10-9 mol/L 1α,25-dihydroxyvitamin D3 group, 1α,25-dihydroxyvitamin D3 plus NIF can increase the proliferation of osteoblasts significantly (P<0.05). ALP activity increased in all different concentrations of 1α,25-dihydroxyvitamin D3 group at 24, 48, 72 h. There was very significant difference between 10-11, 10-9 mol/L group and the control group (P<0.01). NIF (10-8 mol/L) promoted the ALP activity very significantly at 24 and 72 h(P<0.01), while they had no difference at 48 h. The changing trends in the group of 1α,25-dihydroxyvitamin D3 plus NIF group were as well as the control group and the the 1α,25-dihydroxyvitamin D3 group. These showed that 1α,25-dihydroxyvitamin D3 could inhibit the proliferation of osteoblasts, and the mechanism of inhibition involve calcium channels.3 Effects of 1α,25-dihydroxyvitamin D3 on [Ca2+]i of osteoblasts cultured in vitroIn order to observe the effects of 1α,25-dihydroxyvitamin D3 and/or NIF on [Ca2+]i of osteoblasts cultured in vitro, osteblasts isolated from calvaria bone were dealt with various concentrations of 1α,25-dihydroxyvitamin D3 and NIF. 20 min later, the [Ca2+]i of osteoblasts was evaluated. We found that [Ca2+]i in the group of 10-11 mol/L 1α,25-dihydroxyvitamin D3 was lower than the control group significantly (P<0.05) . Compared with the control group, [Ca2+]i in the group of 10-9 and 10-7 mol/L 1α,25-dihydroxyvitamin D3 group increased significantly or very significantly (P<0.05 or P<0.01). Compared with the control group, NIF alone or 1α,25-dihydroxyvitamin D3 plus NIF had not change the [Ca2+]i. However, [Ca2+]i in the united group is lower than that in the group of 10-9 mol/L 1α,25-dihydroxyvitamin D3 significantly (P<0.05). These show that L-type calcium channel plays an important role in the process of [Ca2+]i changing in osteoblasts induced by 1α,25-dihydroxyvitamin D3. |
