Conventional X-ray densitometry detects osteopenia in ovariectomized young rats. Short communication

The present study investigated the reduction on bone density 4 weeks after ovariectomy in rats, with conventional X-ray densitometry. Eighty female Wistar rats underwent bilateral ovariectomy (OVX group) or sham operation (sham group) under general anesthesia. Animals were killed by cervical dislocation 4 weeks after surgery. The left tibia of each animal was dissected and radiographed using oclusal films. Radiographs were scanned and virtual squares on the proximal tibial metaphysis were analyzed with proper software. Higher OD values represent darker areas in the X-ray. After that the tibia were decalcified with EDTA and serial transversal sections with 6 µm of the mesial root of the first mandibular molar were stained with hematoxylin-eosin. Digital images were captured and the densitometric volume of bone was evaluated using software. A significant increase of dark areas in the radiographies of OVX animals was observed when compared with control group (control=1.136±0.020 vs OVX=1.269±0.027, t test, p=0.01). Histomorphometric analysis showed a significant reduction on bone density of OVX animals (control=125.8±20.5 vs OVX=65.4±0.0154, t test, p=0.01). Conventional X-ray densitometry is useful for the characterization of osteopenia in rats after ovariectomy. Besides, 4 weeks are sufficient to cause significant decrease on bone content after ovariectomy.