Abstract
Daily application of parathyroid hormone (PTH 1-34) is used for treatment of osteoporosis. It was investigated whether orchiectomy-induced osteoporotic changes in spine can be ameliorated by every 48h administration of PTH in aged male rats. Eight-month-old male Sprague-Dawley rats were sham operated (n=24) or orchiectomized (Orx, n=36) and maintained untreated over 12 weeks. Thereafter, both tibia underwent transverse metaphyseal osteotomy (Komrakova et al. 2011, J Endocrinol; 209:9-19) and rats were divided into 5 groups treated s.c. as follows: 1) sham vehicle; 2) sham PTH every 24h (PTH/24h); 3) Orx vehicle; 4) Orx PTH/24h; 5) Orx PTH every 48h (PTH/48h). PTH dosage was 40 �g/kg BW per injection. After 5 weeks, lumbar vertebral bodies were used in computed tomographical, biomechanical, histomorphological, ashing and gene expression analyses. Cortical and trabecular densities, biomechanical properties, serum osteocalcin level increased significantly after PTH treatments in all groups (yield load, sham: 232+17N, sham PTH/24h: 376+12N, Orx: 239+16N, Orx PTH/24h: 324+31N, Orx PTH/48h: 297+17N). Bone inorganic weight enhanced after daily PTH application in Orx rats. Bone gene expression did not differ (P>0.05) among the groups. Both PTH administration regimes (24h and 48h) improved impaired bone structure in osteopenic rats. Every 48h application was less effective, however, it improved bone properties to the level observed in healthy (sham) rats. Considering limitation of daily treatments known in humans, these results may be useful for further clinical studies.
Highlights
Evaluation of the lumbar vertebrae is essentially important in the treatment of osteoporosis and osteoporosis related fractures
In the present study we investigated whether orchiectomy-induced osteoporotic changes in spine can be ameliorated by administration of PTH every 48h in aged male rats
The intent of the present study was to investigate the effect of every 48h PTH (1-34) treatment on lumbar spine in osteopenic aged male rats and compare it with every 24h application of the teriparatide
Summary
Evaluation of the lumbar vertebrae is essentially important in the treatment of osteoporosis and osteoporosis related fractures. Hypogonadism or deprivation of androgen by surgical or chemical treatment in men can lead to developing of osteoporosis and increased fracture occurrence [2]. The mortality rate associated with fractures is higher in men than in women [3], though women are at greater risk of developing of osteoporosis. Statistical studies predicted that one out of 5 men aged over 50 would have an osteoporosisrelated fracture [4] and this figure would rise [5]. Despite the statistics and the availability of treatment options, osteoporosis is still under-recognized in men, the treatment remains inadequate and the most studies are still conducted on female subjects [3, 6]
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