Biological effects of tetracycline and doxycycline on cultured human periodontal ligament cells

O bjective To explore the biological effects of tetracycline and doxycycline on cu ltured human periodontal ligament cells(HPDLCs).Methods Increasing concentration s of two drugs(1,5,20,100,500,2500ig/ml)were added to the medium of cult ured HPDLCs separatively.After beening co-incubated for2days,cell morphology was observed un-der reverse microscope;meanwhile,cell proliferation activity was assayed using MTT,the total amount of protein was de-tected by Coumassie Bright Blue method and DNA synthesis was measured by 3 H-TdR.Results Over a concentration range of1to100ig/ml,cell morphology was normal.Moreover,at a concentration range of20to100ig/ml,tetracycline significan tly enhanced the proliferative activity and biosynthesis of HPDLCs(P﹤0.01)while doxycycline significantly promoted DNA synthesis only at the concentration of20 ig/ml.However,higher concentration of the two drugs(2500ig/ml)not only changed cell morphology under microscope,but also significantly inhibited cellular acti vity.Conclusion The results suggested that proper doses of tetracycline could pr omote proliferation and biosynthesis of HPDLCs,while doxycycline had limited eff ects on biobehavior of HPDLCs.Nevertheless,higher concentrations of the two drug s both had cytotoxic effect.