Biochemical studies during aflatoxin B1-induced liver damage in rats fed different levels of dietary protein.

Abstract

AbstractAflatoxin B1 has been fed for 6 months to young rats in low or high protein diets. In agreement with previous research, it was found that the high protein diet was associated with hyperplastic activity in the liver, of a type similar to that usually found in rats developing aflatoxin B1‐induced hepatoma. During the same period, negligible precancerous‐like changes were seen in the rats fed the low protein diet with aflatoxin B1. This model has been used to test the sensitivity of various liver function tests to the dietary‐induced difference in liver reaction to aflatoxin B1 feeding. The serum enzymes lactic dehydrogenase and alkaline phosphatase were considerably elevated in rats with precancerous‐like lesions, but the former was the most sensitive enzyme. Serum glutamate‐oxalate transaminase and serum glutamate‐pyruvate transaminase were both raised in the rats with precancerous‐like lesions, but much less so than lactic dehydrogenase and alkaline phosphatase. Urinary aflatoxin metabolites were also measured. Aflatoxin M1 and aflatoxin P1 were both found after feeding aflatoxin B1. During the feeding period, aflatoxin P1 excretion steadily increased, while aflatoxin M1 increased between the second and fourth months and then fell. In the first 4 months, rats fed a low protein diet tended to produce a lower ratio of aflatoxin M1 to aflatoxin P1 compared to the rats fed a high protein diet. At 6 months, the ratio decreased markedly, especially in the rats with the precancerous‐like lesions. It was concluded that lactic dehydrogenase, alkaline phosphatase, and the ratio of urinary excretion of aflatoxin M1 to aflatoxin P1 could be useful tests for inclusion in a diagnostic procedure for aflatoxin B1‐induced precancerous liver changes that might be expected in human studies.