| Objective:To investigate the influence of overdose Dexamethasone on apoptosis and caspase-3 of osteoblasts in vitro culture;and to investigate the influence of Dexamethasone on apoptosis and caspase-3 of osteoblasts in vitro culture after adding lovastatinMethods:(1) To cultivate osteoblasts from new-born Sprague-Dawley rat calvarias with modified tissue culture in vitro,and purifying osteoblasts with differential velocity adherent technique;(2) The identification of osteoblasts was done by the observation of cell morphology,ALP staining(azo couple methods) and mineralized nodus staining(ARS methods).(3) Osteoblasts of third to fifth generation were divided randomly into six groups: the blank group was treated with DMEM,the control group was treated with Dexamethasone which concentration was 1×10-6mol/l,The Experimental groups were treated with Dexamethasone which concentration was 1×10-66mol/l and lovastain which concentrations were 1×10-9mol/l,1×10-8mol/l,1×10-7mol/l,1×10-6mol/l;cells of each group were incubated for 24h,48h,72h,then were taken out for examination.(4) After treatment for 24h,48h,72h in each group,the apoptosis rate and caspase-3 activity of osteoblast were examined with Apoptotic Cell Hoechst 33258 Detection Kit and Caspase-3 Colorimetric Assey Kit.Results:(1) The cultivated cells were consistent with osteoblasts in morphology,and the results of ALP staining and mineralized nodus staining were positive;(2) Compared with blank group,the control group can increase apoptosis rate of osteoblasts and promote activity of caspase-3,the differences was significant(P＜0.05);(3) Compared with control group,the experimental groups which concentration of lovastatin were 1×10-6mol/l,1×10-7mol/l,1×10-6mol/l can decrease apoptosis rate of osteoblasts and inhibit activity of caspase-3,the differences were significant(P＜0.05),while the experimental group which concentration of lovastatin was 1×10-9mol/l has no influence with osteoblasts in apoptosis rate and activity of caspase-3,there was no statistically significant difference between the groups(P＞0.05).Conclusion:(1) Dexamethasone can induce apoptosis and promote caspase-3 activity of osteoblasts;(2) Lovastatin can partially inhibit apoptosis of osteoblasts induced by Dexamethasone;(3) Dexamethasone probably induces apoptosis of osteoblasts partially by activating caspase-3 in vitro culture.(4) Suppression of apoptosis of osteoblasts,as by Lovastatin,is probably caused by inhibiting activation of caspase-3 induced by Dexamethasone in vitro culture.
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