Effect of a dorsal dermal surgical wound on the chemical response of rat abdominal skin to chronic administration of sodium diphenylhydantoin

Myofibroblasts in phenytoin-induced hyperplastic connective tissue in the rat and in human gingival overgrowth

Phenytoin is a commonly used anticonvulsant drug for the prevention of seizures. A common side effect of phenytoin (PHT) therapy is connective tissue hyperplasia, particularly in the oral cavity manifesting as gingival overgrowth. Our previous studies concerning the molecular mechanisms of drug-induced gingival overgrowth have demonstrated that PHT alters the normal tissue turnover/wound healing signal by causing changes in macrophage phenotype, resulting in the upregulation of essential polypeptide growth factors such as platelet-derived growth factor (PDGF). The cellular consequences of this elevation in growth factor have not been investigated. The present light and electron microscopic study of rat hyperplastic connective tissue and human gingival overgrowth induced by PHT treatment revealed the presence of numerous myofibroblasts. Cells identified as myofibroblasts were evident in all PHT-treated tissue samples and were characterized by an elongated fusiform cell shape, abundant cytoplasmic rough endoplasmic reticulum/polyribosomes, and accumulations of sub-plasmalemmal microfilaments containing spindle densities. These cells were never observed in control tissues. Myofibroblasts are associated with the later stages of tissue turnover, specifically with the transition from the granulation to the remodeling phases of the wound healing process. The presence of myofibroblasts in hyperplastic connective and gingival tissues induced by PHT treatment suggests that PHT exacerbates the normal tissue turnover/wound healing signals responsible for the appearance of myofibroblasts.

Effects of chronic administration of sodium diphenylhydantoin ('Dilantin') on bones and teeth of the rat and hamster: a preliminary study

Male Charles River rats, 31-days old, received i.p. injection of sodium diphenylhydantoin (DPH), 100 mg/kg in 0.9% NaCl, once daily for 26-27 days before death. Male Syrian hamsters, 40-days-old, received similar injections of DPH, 25 mg/kg for 46 days, no treatment for 39 dyas, then DPH FOR A FURTHER 17 DYAS BEfore sacrifice. All rats receiving DPH gained less weight than the controls, and more than 50% displayed acute neurotoxic reactions to the drug; hamsters were not so affected. Morphology and composition of caudal vertebrae, teeth, and jaws from control and DPH-rats were compared on the basis of measurements on radiographs and gross specimens, histological investigation, and determined of % dry volumes of ash, volatile inorganic component, lipid, and organic matrix. DPH-bertebrae were smaller and showed impaired osteogenesis; but chondrogenesis was similar to controls. Overall tail length was similar in both animal groups because caudal intervertebral spaces were wider in DPH-rats, compensating for reduced longitudinal growth of corresponding vertebrae. Incisors were smaller and third molar roots shorter in DPH-rats. In DPH-hamsters the attachment of the periodontal ligament to maxillary incisors was deranged. DPH administration did not change the composition of rat bone or teeth. Densities of dry bones and teeth were in accord with their composition. Possible modes of action of DPH are discussed. Species differences in response of mineralized tissues to DPH administration are emphasized in relation to reports of rickets and osteomalacia in patients on long term DPH therapy.