Effect of nicotine on rat gingival fibroblasts in vitro

Tobacco smoking is considered a major risk factor for the development and p rogression of periodontal diseases (Haber, J. and Wattles, J. (1994). J. Pe riodontol., 64, 16-23). The purpose of this study was to determine the effe cts of nicotine on rat gingival fibroblasts (RGF) cultured in vitro. After ether anesthesia, rat gingival tissues were obtained from the attached ging iva of a Wistar rat. Small fragments of gingiva were maintained in culture in Petri dishes. Fibroblasts developing from these explants were collected to obtain monolayer cultures. After the fourth passage (T4), cells were sup plemented with nicotine at various concentrations. Control and treated cell s were examined under phase contrast or transmission electron microscopy. T hey were compared as regards their DNA content, mitochondrial activity, col lagen and protein synthesis, and cell death by apoptosis or necrosis. Nicot ine from 0.05 mu M to 1 mM did not affect the DNA content or protein and co llagen synthesis. At concentrations between 3 and 5 mM, growth was signific antly diminished and the survival rate reduced. Ultrastructural analysis re vealed dilated mitochondria and vacuolization in treated cells, suggestive of necrosis, but increased apoptosis was also revealed by cytometry. On the basis of this in vitro study, it appears that tobacco, through its compone nt nicotine, may directly affect various functions of RGF.