Toxicological and gene expression analysis of the impact of aflatoxin B1 on hepatic function of male broiler chicks

The objective of this study was to determine the effects of dietary aflatoxin B1 (AFB1) on hepatic gene expression in male broiler chicks. Seventy-five 1-d-old male broiler chicks were assigned to 3 dietary treatments (5 replicates of 5 chicks each) from hatch to d 21. The diets contained 0, 1 and 2 mg of AFB(1)/kg of feed. Aflatoxin B-1 reduced (P < 0.05) feed intake, BW gain, serum total proteins, and serum Ca and P, but increased (P < 0.01) liver weights in a dose-dependent manner. Microarray analysis was used to identify shifts in genetic expression associated with the affected physiological processes in chicks fed 0 and 2 mg of AFB(1)/kg of feed to identify potential targets for pharmacological/toxicological intervention. A loop design was used for microarray experiments with 3 technical and 4 biological replicates per treatment group. Ribonucleic acid was extracted from liver tissue, and its quality was determined using gel electrophoresis and spectrophotometry. High-quality RNA was purified from DNA contamination, reverse transcribed, and hybridized to an oligonucleotide microarray chip. Microarray data were analyzed using a 2-step ANOVA model and validated by quantitative real-time PCR of selected genes. Genes with false discovery rates less than 13% and fold change greater than 1.4 were considered differentially expressed. Compared with controls (0 mg of AFB(1)/kg), various genes associated with energy production and fatty acid metabolism (carnitine palmitoyl transferase), growth and development (insulin-like growth factor 1), antioxidant protection (glutathione S transferase), detoxification (epoxide hydrolase), coagulation (coagulation factors IX and X), and immune protection (interleukins) were downregulated, whereas genes associated with cell proliferation (ornithine decarboxylase) were upregulated in birds fed 2 mg of AFB(1)/kg. This study demonstrates that AFB(1) exposure at a concentration of 2 mg/kg results in physiological responses associated with altered gene expression in chick livers.