title: Pinealectomy affects bone mineral density and structure--an experimental study in sheep.
abstract: BACKGROUND
  Osteoporosis and associated fractures are a major public health burden and there is great need for a large animal model. Melatonin, the hormone of the pineal gland, has been shown to influence bone metabolism. This study aims to evaluate whether absence of melatonin due to pinealectomy affects the bone mass, structure and remodeling in an ovine animal model.
  
  
  METHODS
  Female sheep were arranged into four groups: Control, surgically ovariectomized (Ovx), surgically pinealectomized (Px) and Ovx+Px. Before and 6 months after surgery, iliac crest biopsies were harvested and structural parameters were measured using μCT. Markers of bone formation and resorption were determined. To evaluate long term changes after pinealectomy, bone mineral density (BMD) was analyzed at the distal radius at 0, 3, 9, 18 and 30 months.
  
  
  RESULTS
  Cancellous bone volume (BV/TV) declined after 6 months by -13.3% Px and -21.5% OvxPx. The bone loss was due to increased trabecular separation as well as decreased thickness. The histomorphometric quantification and determination of collagen degradation products showed increased bone resorption following pinealectomy. Ovariectomy alone results in a transient bone loss at the distal radius followed by continuous increase to baseline levels. The bone resorption activity after pinealectomy causes a bone loss which was not transient, since a continuous decrease in BMD was observed until 30 months.
  
  
  CONCLUSIONS
  The changes after pinealectomy in sheep are indicative of bone loss. Overall, these findings suggest that the pineal gland may influence bone metabolism and that pinealectomy can be used to induce bone loss in sheep.
authors: Clinic for Orthopedic Surgery, University Hospital Heidelberg, Germany. marcus.egermann@med.uni-heidelberg.de
authors: Marcus
authors: M
authors: Egermann
authors: Christian
authors: C
authors: Gerhardt
authors: Alain
authors: A
authors: Barth
authors: Georges J
authors: GJ
authors: Maestroni
authors: Erich
authors: E
authors: Schneider
authors: Mauro
authors: M
authors: Alini
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood; D015519:Bone Density; D001862:Bone Resorption / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D007085:Ilium / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D008550:Melatonin / Q000172:deficiency*; D010012:Osteogenesis; D010024:Osteoporosis / Q000000981:diagnostic imaging / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D010052:Ovariectomy; D010870:Pineal Gland / Q000378:metabolism / Q000601:surgery*; D011884:Radius / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D012756:Sheep; D013997:Time Factors; D055114:X-Ray Microtomography
chemical_list: D015415:Biomarkers; D008550:Melatonin