Abstract
Boldenone undecylenate (BOL) is an anabolic androgenic steroid used in livestock to improve growth and food conversion. This study investigated the actions of BOL on structure and functions of rabbit liver as well as the effects of its withdrawal. Eighteen mature male New Zealand rabbits were divided into 2 groups: Control group (n=6) were injected with 0.25 mL corn oil/kg body weight (BW), while BOL group (n=12) received 3 intramuscular injections, 2 wk apart, of BOL (4.5 mg/kg BW). Animals were scarified 1 d after last injection except for 6 rabbits from BOL group that served as the BOL-withdrawal group (4 wk after the 3rd injection). Intramuscular injection of BOL increased (P<0.05) malondialdehyde (MDA) level, but markedly lowered activities of superoxide dismutase (SOD) and catalase (CAT) and reduced glutathione (GSH) concentration compared to both control and BOL-withdrawal groups. Treatment with BOL significantly (P<0.05) increased serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) compared to the control group. BOL injection caused different histopathological alterations and apoptosis in liver, but these changes were less evident in the BOL-withdrawal group. Expression of p53 and tumour necrosis factor-alpha (TNF-alpha) genes was up regulated in BOL compared to control group, while the expressions of p53 and TNF-alpha were down regulated in BOL-withdrawal group in comparison with BOL group. In conclusion, BOL injection induced structural and functional changes in the liver of rabbits, increasing oxidative stress and mediators of apoptosis such as ROS, p53 and TNF-alpha. All these parameters returned to near the control values after withdrawal.