Objective: To explore the biological effects of tetracycline and doxycycline on cultured human periodontal ligament cells(HPDLCs).
Methods: Increasing concentrations of two drugs(1,5,20,100,500,2500 microg/ml)were added to the medium of cultured HPDLCs separately. After being co-incubated for 2 days, cell morphology was observed under reverse microscope; meanwhile, cell proliferation activity was assayed using MTT, the total amount of protein was detected by Coumassie Bright Blue method and DNA synthesis was measured by 3H-TdR.
Results: Over a concentration range of 1 to 100 microg/ml, cell morphology was normal. Moreover, at a concentration range of 20 to 100 microg/ml, tetracycline significantly enhanced the proliferative activity and biosynthesis of HPDLCs (P<0.01) while doxycycline significantly promoted DNA synthesis only at the concentration of 20 microg/ml. However, higher concentration of the two drugs (2500 microg/ml) not only changed cell morphology under microscope, but also significantly inhibited cellular activity.
Conclusion: The results suggested that proper doses of tetracycline could promote proliferation and biosynthesis of HPDLCs,while doxycycline had limited effects on biobehavior of HPDLCs. Nevertheless, higher concentrations of the two drugs both had cytotoxic effect.