Effects of sex hormones on rat tongue carcinoma induced by 4-nitroquinoline 1-oxide (4NQO).

We investigated the regulatory effects of sex hormones on tongue carcinoma initiated by orally administration 4-nitroquinoline 1-oxide (4NQO) to rats. Animals of either sex were classified into three groups. The male rats in each group received an estrogen administration (Me), orchiectomy (Mor), or both treatments (Me/or) while the female rats also received testosterone administration (Ft), ovariectomy (Fov), or both treatments (Ft/ov). The differences in the carcinogenic progress among these groups were examined by macroscopic and microscopic observation of tongue tissues. The incidence of cancer in the tongue tissue was 100% in the group reinforced with testosterone (testosterone+group) (Ft, Ft/ov, Me) but only 56.0% in the group not reinforced with testosterone (testosterone-group) (Fov, Mor). These findings suggest that sex hormones play a role in the onset of 4NQO-induced tongue carcinoma.