Inhibition of nifedipine-induced proliferation of cultured human gingival fibroblasts by Saiko, a Chinese herbal medicine

Saiko is predominantly contained in Saireito, a Chinese herbal medicine. The present study was conducted to determine whether or not Saiko is involved in the inhibition by Saireito of nifedipine‐induced proliferation and collagen synthesis in gingival fibroblasts. Nifedipine (10 µm) significantly enhanced the proliferation starting on day 5 of the culture period. When added together with nifedipine, Saiko at concentrations of 0.05%–0.2% (w/v) dose‐dependently inhibited the nifedipine‐induced proliferation, and at the highest concentration tested (0.2%), Saiko inhibited the nifedipine‐induced proliferation by about 40%. Moreover, Saiko (0.2%) also inhibited the normal proliferation at days 11 and 14. Sole application of nifedipine (10 µm) augmented the release of bFGF, and Saiko concentration‐dependently reduced the level of bFGF in the nifedipine‐containing culture medium. Nifedipine (10 µm) increased the production of type I collagen to almost twice that of the control (normal medium), and Saiko at concentrations above 0.1% significantly reduced the nifedipineinduced production of collagen. In conclusion, the present findings demonstrate that Saiko inhibited the nifedipine‐induced proliferation of gingival fibroblasts by reducing the release of bFGF and that Saiko is involved in the Saireito‐induced inhibition of nifedipine‐stimulated proliferation and collagen synthesis in gingival fibroblasts. Copyright © 2006 John Wiley & Sons, Ltd.