Interaction of fumonisin B1 and aflatoxin B1 in a short-term carcinogenesis model in rat liver

The co-existence of the fumonisin and aflatoxin mycotoxins in corn merited studies to investigate their possible synergistic toxicological and carcinogenic effects. When utilising a short-term carcinogenesis model in rat liver, both the compounds exhibited slow cancer initiating potency as monitored by the induction of foci and nodules stained positively for the placental form of gluthatione-S-transferase (GSTP(+)). However, when rats were treated in a sequential manner with AFB(1) and FB1 the number and size of GSTP(+) lesions significantly increased as compared to the separate treatments. Histopathological analyses indicated that the individual treatments showed far less toxic effects, including occasional hepatocytes with dysplastic nuclei, oval cell proliferation and, in the case of FBI, a few apoptotic bodies in the central vein regions. The sequential treatment regimen induced numerous foci and dysplastic hepatocyte nodules, and with oval cells extending from the periportal regions into the centrilobular regions. This would imply that, in addition to the cancer promoting activity of FBI of AFB(1)-initiated hepatocytes, the AFB(1) pre-treatment enhanced the FBI initiating potency, presumably by rendering the liver more susceptible to the toxic effects of FBI. The co-occurrence of AFB(1) and FB1 in corn consumed as a staple diet could pose an increased risk and should be included in establishing risk assessment parameters in humans. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.