Evaluation of bone quality and quantity in osteoporotic mice--the effects of genistein and equol.

The technology of gene manipulation is often used in mice. A crucial point for osteoporosis research is the evaluation of biomechanical and morphologic parameters. These parameters, however, are difficult to measure in mice. Nevertheless, this study demonstrates the capability of using techniques for the evaluation of bone quality and quantity after various treatments in osteopenic mice. After ovariectomy, 60 C57BL/6J mice were divided into 4 groups and were fed a soy-free diet (C) supplemented with estradiol, genistein or equol for 3 months. To analyze the osteoprotective effects of the tested supplements, we evaluated the bone biomechanical properties, histomorphometric changes and bone mineral density of the proximal tibiae metaphysis. The biomechanical parameters of genistein (GEN) were shown to be similar to those levels observed with estradiol (E). The biomechanical parameters of both GEN and E were significantly superior to those observed with C. Supplementation with equol (EQO) demonstrated higher mean biomechanical values than those observed with C. The histomorphometric evaluation demonstrated an increased number of nodes in mice treated with GEN and E as compared to the mice treated with EQO and C. Treatment with E and EQO led to improved cortical bone, which was only partly seen with the mice treated with GEN. The analysis of the bone mineral density (BMD) demonstrated that treatment with GEN and E resulted in a significant improvement as compared to the mice treated with C, while the cancellous density was significantly increased in all of the supplementation groups. This study conclusively demonstrated that bone quality and quantity parameters can be measured in mice. Furthermore, biomechanical and morphologic evaluations were shown to be reliable for use in mice. Further studies may combine these techniques with gene manipulation technology to better understand osteoporosis. Treatment with GEN resulted in improved biomechanical results and enhancement of morphologic parameters.