Effect of Neonatal Exposure to Genistein on Bone Metabolism in Mice at Adulthood

Abstract

Infants fed soy-based infant formulas are exposed to high levels of genistein, an isoflavone, with potential estrogen-like activity. This study determined whether neonatal exposure of mice to genistein resulted in higher bone mineral density (BMD) and greater resistance to fracture at adulthood. Male and female CD-1 mice (n = 4-14/group) were randomized to control (CON) (corn oil, s.c.), diethylstilbestrol (DES) (2 microg/pup/d, s.c.), or genistein (GEN) (4 microg/pup/d, s.c.) from d 1 through 5 of life. At 21 d of age, pups were weaned and studied until 4 mo of age when tissues were collected. Among females, femur (p = 0.016) and lumbar vertebrae (LV1-LV4) (p < 0.001) BMD were higher among DES and GEN groups compared with CON group. Importantly, the higher LV1-LV4 BMD was associated with stronger vertebrae that were more resistant to fracture as the peak load of LV3 (p = 0.012) was higher in the GEN and DES groups compared with CON group. In males, DES and GEN had divergent effects on femur and lumbar vertebrae BMD and peak load. In conclusion, early exposure to GEN has positive effects on femur and lumbar spine of females, likely due to estrogenic effects, while only the lumbar spine of males benefits from early exposure to GEN.