| Summary: | 碩士 === 國防醫學院 === 生物及解剖學研究所 === 88 === The purposes of this study were 1) to establish a suitable androgen deficiency-induced osteopenia animal model and 2) to investigate the precise effects of estradiol and testosterone on orchidectomy-induced osteopenia in aged male rats. Seventy 12-month-old male Sprague-Dawley rats were assigned into 7 groups [baseline, control, sham-operated (Sham), orchidectomized (ORX), orchidectomized with estradiol (ORX+E2), and orchidectomized with testosterone/proscar (specific inhibitor of 5a-reductase)/arimidex (specific non-steroidal aromatase inhibitor)(ORX+1TPA or ORX+5TPA)]. The parameters of bone formation and bone resorption were measured and evaluated using serum biochemical assay [measurements of testosterone, estradiol and C-terminal telopeptide of typeⅠcollagen (ICTP)], and static and dynamic bone histomorphometry. In addition, measurement of bone mineral density (BMD) of rat lumbar vertebrae (L1-L6) was performed using dual energy X-ray absorptiometry (DEXA) with small animal software. Significant decreases in serum testosterone (p<0.05) and lumbar vertebrae BMD (p<0.05) while significant increases in serum ICTP (p<0.01) were noted in ORX group as compared to the control group. Bone histomorphometric analysis revealed that significant increases in N.Oc/B.Pm, N.Oc/B.Ar, ES/BS and trabecular separation, and significant decreases in BV/TV, trabecular area and trabecular thickness in ORX group as compared to the control group (p<0.05 and 0.01). E2 treatment resulted in significant decreases in histomorphometric indices of bone turnover and increases in BV/TV and trabecular area (p<0.01 vs ORX). 5TPA treatment (without the effects of estradiol and dihydrotestosterone) showed more effective in preventing bone loss as compared to the ORX+E2 group. The results of this study indicated that: 1) androgen deficiency resulted in dramatic bone loss and decline in BMD and 2) both E2 and 5TPA effectively prevent ORX-induced bone loss
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