Decreased Ultrasonic Wave Velocity in Bones of Ovariectomized and Spontaneous-Menopause Mice

Osteoporosis fractures are a significant social problem. Despite having sufficient bone mineral density (BMD), postmenopausal women frequently experience bone fractures. This study investigated the effect of estrogen reduction on bone elasticity by comparing young female C57BL/6J mice that underwent either Sham or ovariectomized (OVX) surgery. Bone properties in two-year-old mice (post-senescence period: spontaneous menopause (SM)) were also examined. OVX mice were consistently heavier than Sham mice and showed increased visceral fat. Longitudinal wave velocities in tibia bones of these groups were evaluated using a micro-Brillouin scattering technique (μ-BS). OVX mice bones exhibited a significant decrease in velocity (2.0-2.3% lower) at 24 weeks after surgery. The velocities in the tibia bones decreased more significantly in SM mice than in OVX mice. These findings highlight the effects of estrogen deficiency on bone elasticity in young mice during growth and identify additional age-related changes.