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BioMed Research International
Volume 2015 (2015), Article ID 454162, 11 pages
Research Article

Modifications in Bone Matrix of Estrogen-Deficient Rats Treated with Intermittent PTH

1Department of Morphology and Genetics, School of Medicine, Federal University of São Paulo, 04023-900 São Paulo, SP, Brazil
2Mineralized Tissue and Histology Research Laboratory, Department of Morphology and Genetics, Federal University of São Paulo School of Medicine (UNIFESP), Rua Botucatu, 740 Vila Clementino, 04023-900 São Paulo, SP, Brazil
3Department of Biochemistry, School of Medicine, Federal University of São Paulo, 04044-020 São Paulo, SP, Brazil
4Department of Physiological Sciences, Federal University of São Carlos, 13565-905 São Carlos, SP, Brazil
5Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
6Roudebush Veterans Administration Medical Center, Indianapolis, IN 46202, USA

Received 26 July 2014; Revised 21 November 2014; Accepted 21 November 2014

Academic Editor: Kazim Husain

Copyright © 2015 Rafael Pacheco-Costa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Bone matrix dictates strength, elasticity, and stiffness to the bone. Intermittent parathyroid hormone (iPTH), a bone-forming treatment, is widely used as a therapy for osteoporosis. We investigate whether low doses of intermittent PTH (1-34) change the profile of organic components in the bone matrix after 30 days of treatment. Forty 6-month-old female Wistar rats underwent ovariectomy and after 3 months received low doses of iPTH administered for 30 days: daily at 0.3 µg/kg/day (PTH03) or 5 µg/kg/day (PTH5); or 3 times per week at 0.25 µg/kg/day (PTH025). After euthanasia, distal femora were processed for bone histomorphometry, histochemistry for collagen and glycosaminoglycans, biochemical quantification of sulfated glycosaminoglycans, and hyaluronan by ELISA and TUNEL staining. Whole tibiae were used to estimate the bone mineral density (BMD). Histomorphometric analysis showed that PTH5 increased cancellous bone volume by 6% over vehicle-treated rats. In addition, PTH5 and PTH03 increased cortical thickness by 21% and 20%, respectively. Tibial BMD increased in PTH5-treated rats and this group exhibited lower levels of chondroitin sulfate; on the other hand, hyaluronan expression was increased. Hormonal administration in the PTH5 group led to decreased collagen maturity. Further, TUNEL-positive osteocytes were decreased in the cortical compartment of PTH5 whereas administration of PTH025 increased the osteocyte death. Our findings suggest that daily injections of PTH at low doses alter the pattern of organic components from the bone matrix, favoring the increase of bone mass.