Hepatic effects of long-term tamoxifen administration to cycling female rats.

The metabolic implications of tamoxifen (TAM) used as preventive therapy of young premenopausal women with high risk of breast cancer is unknown. To unravel this problem, an animal model of long-term TAM administration to cycling young adult female rats was used to evaluate its effects in the liver. Body weight and food consumption were monitored, and at the end of the study, both parameters were lower in TAM-treated rats. Biochemical measurements showed that the TAM administration induced alterations in serum levels of liver enzymes when compared with control rats at different stages of the estrous cycle. In TAM-treated rats, lower glycogen storage was observed in hepatocytes close to the portal areas and pericentrolobular cells had a higher concentration of glycogen. Liver sections of TAM-treated rats presented mild steatosis-a high percentage of area occupied by lipid droplets in the hepatocytes. These results point to metabolic changes upon long-term TAM therapy.