Abstract

The effect of the non-steroidal anti-inflammatory drug indomethacin on 1-hydroxyanthraquinone (1-HA)-induced carcinogenesis was investigated in male ACI/N rats. Animals were fed the diet containing 1.5% 1-HA and simultaneously given indomethacin solution (16 p.p.m.) as drinking water for 48 weeks. The incidences of large bowel neoplasms (adenomas and adenocarcinomas) and forestomach (papillomas) in rats given 1-HA and indomethacin (large intestinal tumors: 0/14, 0%; forestomach tumors: 2/14, 14%) were significantly lower than those in rats given 1-HA alone (large intestinal tumors: 12/27, 44%; forestomach tumors: 14/27, 52%) (P = 0.002 and P = 0.01 respectively). Liver cell adenomas were developed in a rat given 1-HA and no liver tumors in rats treated with 1-HA and indomethacin. Altered liver cell foci were present in rats given 1-HA alone (18/27, 67%) and those given 1-HA and indomethacin (8/14, 57%), but no significant difference in the incidence between the two groups was found. Untreated animals and rats given indomethacin alone had no neoplasms in the large bowel, forestomach and liver. Thus, the non-steroidal anti-inflammatory drug indomethacin significantly inhibited carcinogenesis induced by the naturally occurring carcinogen, 1-HA.