title: Synergistic effect of parathyroid hormone and growth hormone on trabecular and cortical bone formation in hypophysectomized rats.
abstract: OBJECTIVE
  Growth hormone (GH) deficiency in pediatric patients results in short stature and osteopenia. We postulated that the GH and parathyroid hormone (PTH) combination would result in improvement in bone growth and bone formation.
  
  
  METHODS
  Forty hypophysectomized female rats at age 8 weeks were divided into hypophysectomy (HX), HX + PTH (62.5 microg/kg, s.c. daily), HX + GH (3.33 mg/kg, s.c. daily), and HX + PTH + GH for a 4-week study.
  
  
  RESULTS
  GH increased body weight, bone growth, bone mineral content (BMC) and bone mineral density (BMD), whereas PTH increased BMC and BMD without a significant effect on bone size. GH increased both periosteal and endocortical bone formation and cortical size, while PTH increased only endocortical bone formation. GH mitigated the trabecular bone loss by increasing bone formation, while PTH increased bone mass by increasing bone formation and suppressing osteoclast number per bone area. The result of combined intervention shows an increase in trabecular, periosteal and endocortical bone formation and suppression of bone resorption resulting in a synergistic effect on increasing trabecular and cortical bone volume and BMD.
  
  
  CONCLUSIONS
  The combination treatment of PTH and GH increases bone growth, bone formation, decreases bone resorption and has a synergistic effect on increasing bone density and bone mass.
authors.affiliation: Department of Pediatric Endocrinology, Winthrop University Hospital, Mineola, NY 11501, USA. snguevarra@yahoo.com
authors.forename: Maria Sarah N
authors.initials: MS
authors.lastname: Guevarra
authors.forename: James K
authors.initials: JK
authors.lastname: Yeh
authors.forename: Mariano
authors.initials: M
authors.lastname: Castro Magana
authors.forename: John F
authors.initials: JF
authors.lastname: Aloia
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000187:drug effects / Q000502:physiology; D001851:Bone Diseases, Metabolic / Q000503:physiopathology*; D001842:Bone and Bones / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D004357:Drug Synergism; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D007016:Hypophysectomy; D008856:Microscopy, Fluorescence; D010281:Parathyroid Hormone / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010281:Parathyroid Hormone; D013006:Growth Hormone