Experimental Study On Osteoporosis In Adult Rats

Osteoporosis describes the depletion of bone mass which, with architectural modification, lead to reduction of bone strength and increased risk of fracture. Estrogen deficiency and immobilization lead to rapid loss of bone. Estrogen, calcitonin and alendronate are antisorptive agents, so two experiments have been done blow: 1: Treatment with calcitonin or alendronate prevents immobilization-induced loss of bone in adult female rats To assess the effects of two antiresorption agents, calcitonin(CT) or alendronate(ALN), on the immobilization-induced bone loss and strength in rats, 28rats were divided into 4 groups: 1 normal group; 2 immobilization control (1mm); 3 Imm+CT2U/kg body weight/day(bw/day); 4 Inm+AIN2mg/kg.bw/day. In groups 2- 4 the left hind leg was immobilized with sciatic neurectomy, 50 days later they were sacrificed, the effects of unilateral hindlimb immobilization and of treatment were determined by DEXA measurement on femora at three different sites.. by biomechanical testing of femora and by histomorphometry on the proximal tibial metaphysis, bilateral measurement were performed. Immobilization induced a significant loss of BMD~ trabecular bone volume (TBV) and bone strength, both CT and ALN treatment showed a protection against the immobilization loss of BMD, bone strength and TB\~. ffi conclusion, In rat 50 days hindlimb-immobilization affects the bone metabolism significantly, both calcitonin and alendronate can prevent the deterioration of bone induced by immobilization. 2: Effects of early estrogen replacement on trabecular bone in the rat To evaluate the ability of estrogen replacement therapy (ERT) to prevent changes in trabecular bone volume(TBV), bone mineral density(BMD) and connectivity beginning either at ovariectomy(OVX) or 10-20 days after OVX m adult female rats, 40 rats was divided into 5 groups, groups 2-5 had bilateral OVX, while groupl was sham-ovanectomied on day 0. Animal were treat with vehicle (groupsl and 2) or ERT starting at days 0,10,20 post-ovx (groups 3-5), III 8 weeks later they were sacrificed, trabecular variables were calculated from histomorphometiy and DEXA. Animal given ERT from the time of OVX maintain the BMD, TBV and trabecular connectivity, however, OVX animal treat with vihicle deteriorated greatly, ERT innitiated at day 10 and 20 restored BMD and TBV partly, but the trabecular connectivity were not restored. In conclusion, ERT can restore the lost bone, but cannot restore the trabecular connectivity.