Expression of metallothionein message after phenytoin injection in rat gingiva

Phenytoin (PHT)is an anticonvulsant drug and a long term treatment with PHT is known to produce a gingival overgrowth as the side effect. We previously reported that injection of PHT to the rats for 42 days induced a gingival overgrowth in molar region of the teeth mandible. Metallothionein (MT) s are intracellular metal binding proteins which can scavenge free radicals and maltipotential proteins. The aim of this study was to clarify the role of MT in gingival overgrowth by PHT administration. A dose of PHT 50 mg/kg/day was injected s. c. into 3 weeks old rats twice a day for 7 days. Twelve hours after the last injection, gingiva was removed and the isoform-specific expressions of MT mRNAs (MT-II) were observed using RT-PCR method. The gingival overgrowth of the molars showed no difference between the PHT injected group and the control group. MT-II mRNA level increased after PHT injection. The synthesis of MT may be associated with the gingival overgrowth by PHT.