Intracellular glutathione: a main factor in TEGDMA-induced cytotoxicity?

OBJECTIVE

To evaluate whether the reduction/prevention of triethylene glycol dimethacrylate (TEGDMA)-induced decrease of intracellular glutathione (GSH) protects human periodontal ligament fibroblasts (HPLF) against cell death.

METHODS

HPLF were preincubated for 30 min with exogenous GSH and then treated with TEGDMA (2.5 mM) with/without GSH (0.5-2.5-5 mM) for the following incubation exposure types: 6h (GI); 6h followed by 18 h recovery time in presence (GII) or absence (GIII) of exogenous GSH; 24 h without recovery time (GIV). TEGDMA-cytotoxicity and intracellular glutathione were assessed by Hoechst 33342 and monobromobimane (MBBr) assays. Data were statistically analyzed with Bonferroni ANOVA (p<0.05).

RESULTS

Preincubation with exogenous GSH increased the intracellular GSH-concentration. TEGDMA was cytotoxic at all treatment times except at 6h (GI) (94±7% of control). In GII the treatment with TEGDMA alone (59±7%) showed no different results to cultures exposed to TEGDMA and GSH. Exogenous GSH had no effect on the TEGDMA-induced cytotoxicity also in the GIII and GIV. Thus, a combined incubation with GSH did not prevent the cytotoxicity of TEGDMA, despite of a significant increase of intracellular GSH-concentration in the presence of exogenously supplied GSH.

SIGNIFICANCE

The glutathione-decreasing effect of TEGDMA is not the major cause of TEGDMA-induced cytotoxicity, indicating more complex mechanisms, which are causative for TEGDMA-cytotoxicity in HPLF.