Influence of lithocholic acid on 2-aminoanthracene-induced alterations in DNA synthesis in rat tissues in vivo.
Patterns of DNA synthesis in skin, liver, jejunum and colon of weanling, male Sprague-Dawley rats were monitored for 120 h following the administration of a single carcinogenic dose of 2-aminoanthracene (2-AA) or lithocholic acid (LA) or both. IN the skin, liver and colon 2-AA alone induced a slight inhibition of DNA synthesis during the first 16 h. Simultaneous treatment with 2-AA and LA gave a similar result up to 48 H, beyond which there was a significant enhancement of DNA synthesis. In contrast, [3H]-thymidine incorporation in the jejunum following 2-AA treatment was stimulated during the first 8 h and again beyond 72 h with normal levels of activities in the intervening period. Inclusion of LA increased the time of stimulation up to 48 h, but beyond 72 h it negated the stimulation induced by 2-AA alone. Thus, since in the presence of LA, colon and not the jejunum shows of DNA synthesis pattern similar to that in skin and liver, two 2-AA induced cancer sites, it is postulated that the colon and not the jejunum may be a putative site for 2-AA induced carcinogenesis if the LA content of the former is enriched.更多