Comparison of osteopenia after gastrectomy, ovariectomy and prednisolone treatment in the young female rat

Rat models of osteopenia include ovariectomy and long-term glucocorticoid t reatment. Although ovariectomy produces significant trabecular bone loss af ter 2 weeks, long-term glucocorticoid treatment has been reported to cause osteopenia in some studies but not in others. In the present 8-week-study, we compared the osteopenia associated with gastrectomy (GX) to that induced by ovariectomy (OVX) or prednisolone (PRE) treatment. Female Sprague-Dawle y rats (10 weeks old) were subjected to GX, OVX, PRE treatment or SHAM oper ation. At the end of the study, calvariae, femurs and fifth lumbar vertebra e (L5) were collected and subjected to bone density measurement (femur and L5), transillumination (calvaria) and histomorphometry (calvaria and femur) . Bone density was reduced in L5 and the distal femur in the OVX and GX gro ups, but not in the PRE group. Transillumination of the calvaria showed mar ked bone loss in the GX rats, but not in the other groups. Morphometric ana lysis of the femur revealed reduced trabecular bone volume, trabecular thic kness, trabecular number and osteoclast number, but increased osteoclast su rface (expressed as per cent of the trabecular bone surface covered by oste oclasts) in the GX and OVX rats. The PRE rats seemed unaffected. Cortical t hickness was reduced in the GX rats, but not in the other groups. The findi ngs indicate that GX induces osteopenia in, e.g., femur and vertebra of a m agnitude similar to or greater than that induced by OVX, while at the same time inducing osteopenia in the calvaria. Although osteoclast activation se ems to contribute, the precise mechanism underlying the GX-evoked osteopeni a remains obscure.