[Effects on the expression of NF-kappaBp65 of osteoblast-like cell under stretch load with different daily loading...

The purpose of this study was to investigate the effect on the expression of NF-kappaBp65 of osteoblast-like cell under stretch load with the same amplitude but different daily loading times. The osteoblast-like cells MG-63 were passage cultured and stretched by the four-point-bend loading device; based on the daily loading times, the osteoblast-like cells were randomly divided into four groups. The first was the control, the others were stretched with mechanical tension with the same amplitude of 2,000 mu strain and at the same frequency of 0.5 Hz., but the daily loading times were 1 time/d, 2 times/d, 4 times/d differently for each group, the periods of mechanical tension applied to the cells of the three groups were all 60 min/d and lasted for 2d total. After the cells being streteched, the expression levels of NF-kappaBp65 of the osteoblast-like cells of the three groups and control group were investigated by using the techniques of immunohistochemistry, and were compared with each other. The results showed that the positive expression ratios of the four groups were different significantly; the positive expression ratio of the control was lower than those of the other three groups; the positive expression ratio of the 4 times/d group was higher than those of the other two stretched groups; the positive expression ratio of the 2 times/d group was higher than that of the 1 time/d group. The results suggested that when the osteoblast-like cell was under the stretch load with different daily loading times but the same amplitude, the expression ratio of NF-kappaBp65 in the cell increased with the rising of the stimulating times. It means that the mechanical strain with high daily loading times could promote the transcriptional level of osteoblast-like cell more effectively.