Effects of aflatoxin B1 on the cell cycle distribution of splenocytes in chickens

The purpose of the present study was to evaluate effects of aflatoxin B-1 (AFB(1)) on the cell cycle and proliferation of splenic cells in chickens. A total of 144 one-day-old Cobb male chickens were randomly divided into 2 equal groups of 72 each and were fed on diets as follows: a control diet and a 0.6 mg/kg AFB(1) diet for 21 days. The AFB(1) diet reduced body weight, absolute weight and relative weight of the spleen in broilers. Histopathological lesions in AFB(1) groups were characterized as slight congestion in red pulp and lymphocytic depletion in white pulp. Compared with the control group, the expression levels of ataxia-telangiectasia mutated (ATM), cyclin E-1, cyclin-dependent kinases 6 (CDK6), CDK2, p53, p21 and cyclin B-3 mRNA were significantly increased, while the mRNA expression levels of cyclin D-1, cdc2 (CDK1), p16, p15 were significantly decreased in the AFB(1) groups. Significantly decreased proliferating cell nuclear antigen (PCNA) expression and arrested G(0)G(1) phases of the cell cycle were also seen in the AFB(1) groups. In conclusion, dietary AFB(1) could induce cell cycle blockage at G(0)G(1) phase and impair the immune function of the spleen. Cyclin D-1/CDK6 complex, which inhibits the activin/nodal signaling pathway, might play a significant role in the cell cycle arrest induced by AFB(1).