Low-exposure cadmium is more toxic on osteoporotic rat femoral bone: mechanical, biochemical, and histopathological evaluation.

This study aimed to investigate the effects of low-exposure Cd on normal and osteoporotic bone. For this purpose, 12-week-old Sprague-Dawley female rats were assigned randomly to a control group, a Cd group, and an ovariectomy (OVX)+Cd group. OVX+Cd rats underwent bilateral ovariectomy via ventral incision. Twelve weeks after ovariectomy, cadmium chloride (CdCl(2)) was given to rats (Cd and OVX+Cd groups) as intraperitoneal (ip) injection of 0.5mg/kg three times a week for 18 weeks and distilled water was given to control group via ip route for 18 weeks. Bone mineral density (BMD) was measured at mid-diaphysis femoral region by dual-energy X-ray absorbsiometry. Cross-sectional area of the femoral shaft was evaluated by computerized tomography. Biomechanical measurements were performed at the mid-diaphysis of the left femur. Collagen fibers were evaluated at light microscopic level. BMD, cortical thickness, cortical area, and femur length were not changed in Cd and OVX+Cd groups in comparision to controls. In the OVX+Cd group, strength, displacement, energy, stress, strain, and toughness were significantly lower than those of the control group. The Cd concentration of bone was significantly increased in the OVX+Cd group compared to that in the control group. Collagen fiber intensity was decreased in all groups except control group. The results of the present study indicate that the administration of low-dose Cd does not affect normal bone biomechanical parameters, but it has a significant effect on osteoporotic bone.