title: Separate and combined effects of growth hormone and parathyroid hormone on cortical bone osteopenia in ovariectomized aged rats.
abstract: The focus of this study is on whether cortical osteopenia occurs in ovariectomized aged female rats, and if so, whether growth hormone (GH) and parathyroid hormone (PTH) independently or together (GH+PTH) can rebuild the lost cortical bone. Tibio-fibula junction was analyzed by histomorphometry and peripheral quantitative computerized tomography (pQCT) densitometry. Significant loss of cortical bone area (Ct. BAr), cortical bone mineral content (Ct. BMC), cortical thickness (Ct. Th) and increase of endocortical perimeter occurred 4 months after ovariectomy. The rats were given GH, PTH, GH+PTH or vehicle for 2 months and sacrificed. GH, PTH and GH+PTH increased Ct. BAr, Ct. BMC, Ct. Th, periosteal perimeter, periosteal double-labeled perimeter, mineral apposition rate, and bone formation rate, but decreased marrow area. PTH and GH+PTH decreased endocortical perimeter, and increased endocortical double labeled perimeter and bone formation rate. In conclusion, ovariectomy induced cortical bone loss in aged rats by increasing endocortical bone resorption. Growth hormone increased periosteal bone formation, while PTH stimulated endocortical bone formation and in combination GH+PTH produced complementary effects thereby reversing osteopenia.
authors.affiliation: Department of Physiology, The University of Texas Health Science Center at San Antonio, 78229-3900, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Banu
authors.forename: P B
authors.initials: PB
authors.lastname: Orhii
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: D N
authors.initials: DN
authors.lastname: Kalu
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D015519:Bone Density / Q000187:drug effects; D001851:Bone Diseases, Metabolic / Q000188:drug therapy*; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D009929:Organ Size; D010052:Ovariectomy; D010281:Parathyroid Hormone / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D013977:Tibia / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed
chemical_list: D010281:Parathyroid Hormone; D013006:Growth Hormone