Pathological effects of N-methyl-N'-nitro-N-nitrosoguanidine on oral mucosa in Wistar rats after transplacental exposure.

This study examined the effects of N-methyl-N'-nitro-N-nitrosoguanidine (M.N.N.G.) on the oral mucosa of Wistar rats. The rats were born from dams treated by i.p. injections of M.N.N.G. during gestation. Each pregnant rat of a first group received a total dose of 39.60 mg/kg of M.N.N.G. administered throughout the gestation period. Each pregnant rat of a second group received a total dose of 82.50 mg/kg of M.N.N.G. by i.p. injections during the first ten days of gestation. In the progeny of dams from both groups, the morphology of the gingiva was modified. The lingual gingiva from the lower jaw was most impaired. The epithelium always displayed hyperplasia: acanthosis, papillomatosis and hyperkeratosis. These results indicate a pathogenic effect of M.N.N.G. on lingual, mandibular gingiva. This effect was slight but permanent and irreversible. No carcinogenic effect was noticed on the oral mucosa. Similarities between the lesions described in this work and human epithelial dysfunction makes this experimental model interesting.