title: Maintenance of bone mass by physical exercise after discontinuation of intermittent hPTH(1-34) administration.
abstract: Human PTH(1-34) has been recognized for its marked anabolic effect on bone, but that effect has been reported to be lost after cessation of PTH treatment. The objective of this study was to determine the fate of hPTH-stimulated bone and whether this anabolic effect of PTH could be maintained by daily exercise. Eleven-week-old Sprague-Dawley rats were ovariectomized (OVX) and human PTH(1-34) (30 micrograms/kg) was injected subcutaneously three times per week for 12 weeks beginning one week after surgery. After the cessation of PTH treatment, treadmill exercises were performed for 8 weeks (15.7 m/min, 1 h/day, 5 days/week). The results of histomorphometric assessment in the proximal tibial metaphysis demonstrated that hPTH treatment partially prevented OVX-induced cancellous bone loss. Eight weeks following the cessation of PTH treatment, PTH-stimulated bone mass went back to the OVX control level. Daily exercise did maintain PTH-stimulated bone mass; however, this exercise did not increase the bone mass in PTH-untreated OVX rats.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Niigata University, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yamamoto
authors.forename: H E
authors.initials: HE
authors.lastname: Takahashi
authors.forename: T
authors.initials: T
authors.lastname: Tanizawa
authors.forename: R
authors.initials: R
authors.lastname: Fujimoto
authors.forename: T
authors.initials: T
authors.lastname: Hara
authors.forename: S
authors.initials: S
authors.lastname: Tanaka
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D015519:Bone Density / Q000187:drug effects; D001862:Bone Resorption; D001842:Bone and Bones / Q000033:anatomy & histology; D002113:Calcification, Physiologic; D005260:Female; D007279:Injections, Subcutaneous; D010012:Osteogenesis; D010024:Osteoporosis / Q000517:prevention & control*; D010052:Ovariectomy; D010281:Parathyroid Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology*; D010805:Physical Conditioning, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D019379:Teriparatide; D013977:Tibia
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; D019379:Teriparatide