甲状旁腺激素对大鼠成骨细胞增殖分化的影响

目的 探讨甲状旁腺激素(parathyroid hormone,PTH)对大鼠成骨细胞增殖及相关细胞因子的调节作用.方法 将传代的成骨细胞分为对照组、PTH持续给药组、PTH间歇给药组.持续给药组48 h中持续给药;PTH间歇给药组前6 h给予PTH,后42 h撤除;对照组予溶媒液.每48 h为一循环,持续作用8个循环,每个循环结束时,MTT法测定细胞增殖,检测碱性磷酸酶(ALP)活性,实时荧光定量PCR法(RT-PCR)测定胰岛素样生长因子-1(IGF-1)、骨形态发生蛋白-2(BMP-2)的表达水平.结果 间歇给药组细胞增殖在第7、8个循环时明显增加;而持续给药组在第5个循环时达到峰值,随后逐渐低于其他两组,在第7、8个循环时抑制作用明显.1～4个循环时3组间ALP活性差异无统计学意义,第5～8个循环ALP活性显著增加;持续给药组第6～8个循环对ALP活性有明显抑制作用.间歇给药组细胞IGF-1 mRNA的表达在第6个循环时达到高峰后有所下降,但始终明显高于其他两组;持续给药组前期IGF-1 mRNA表达水平较高,而后期则明显低于对照组.间歇给药组BMP-2 mRNA表达水平持续升高;持续给药组前3个循环表达水平较高,随给药时间的增长呈下降趋势.结论 间歇给予一定浓度的PTH可刺激成骨细胞的增殖与分化,后期作用大于前期.给药前期的ALP水平主要与IGF-1 mRNA表达水平相关,而后期则可能是通过BMP-2 mRNA表达的升高使ALP活性增强.

The effects of parathyroid hormone on proliferation of rat osteoblasts

Objective The effects of parathyroid hormone(PTH)on proliferation of osteoblast and the related cytokines expression were investigated.Methods The osteoblasts were divided into three groups according to the mode of exposure to PTH:intermittent exposure group, continuous exposure group,and vehicle-treated group.In the intermittent exposure group,the cells were exposed to PTH for the first 6 h of each 48 h incubation cycle, and then cultured in the absence of PTH during the remainder of the cycle.In the continuous exposure group.the cells were exposed to PTH for 48 h.Every 48 h was considered as a cycle.At each end of cycle, the cells were harvested to measure MTT value and ALP activity.mRNA level of IGF-1 and BMP-2 were determined by RT-PCR.Results MTF results showed the cells proliferation increased in the intermittent exposure group at 7th and 8th cycles.In the continuous exposure group,the proliferation of osteoblasts reached peak at 5th cycle,and decreased greatly at 7th and 8th cycles.ALP activity of three groups had no significant difference in 1-4 cycles.ALP activity of the group increased greatly in 5-8 cycles,but that of the continuous exposure group decreased greatly.The IGF-1 mRNA expression in the intermittent exposure group reached peak at the 6th cycle.Its expression level decreased gradually after that,although its level was always the highest among the three groups.In the continuous exposure group,IGF-1 mRNA expression level was higher during the early cycles, but decreased in the later cycles.BMP-2 mRNA expression level in the intermittent exposure group increased gradually.The BMP-2 expression level in the continuous exposure group was higher during the 1-3 cycles,but decreased greatly in 6-8 cycles.Conclusion PTH intermittent treatment can enhanced osteoblast proliferation and differentiation at the later period.The increase of ALP activity is related to IGF-1 and BMP-2 in early or later phase of proliferation separately.