title: The effects of orchidectomy and supraphysiological testosterone administration on trabecular bone structure and gene expression in rats.
abstract: OBJECTIVE
  This study aimed to determine the effects of orchidectomy and supraphysiological testosterone replacement on trabecular structure and gene expression in the bone.
  
  
  METHODS
  Twenty-four 3-month old male rats were randomized into sham (SH), orchidectomized (ORX) and testosterone-treated (TE) groups. Orchidectomy was performed on the ORX and TE group. Weekly testosterone enanthate intramuscular injection at 7 mg/kg body weight was administered to the TE group for 8 weeks while the other groups received peanut oil as vehicle. Blood was collected before and after treatment for serum testosterone analysis. The femora and tibiae were harvested after the treatment period for trabecular structure and gene expression analysis.
  
  
  RESULTS
  The trabecular bone volume decreased significantly and the porosity increased significantly in the ORX group compared to the SH group (p < 0.05). Testosterone treatment prevented all these changes (p < 0.05). The expression of osteogenic genes decreased significantly in the ORX group compared to the SH group (p < 0.05). Testosterone treatment decreased the expressions of RANKL and OPG genes significantly (p < 0.05).
  
  
  CONCLUSIONS
  Orchidectomy-induced degeneration in trabecular structure is caused by a decrease in the expressions of osteogenic genes. Supraphysiological testosterone replacement is able to prevent these degenerative changes in the bone despite the modest changes in gene expression.
authors.affiliation: Faculty of Medicine, Department of Pharmacology, Universiti Kebangsaan Malaysia , Kuala Lumpur , Malaysia.
authors.forename: Kok-Yong
authors.initials: KY
authors.lastname: Chin
authors.forename: Soelaiman
authors.initials: S
authors.lastname: Ima-Nirwana
mesh_terms: D000818:Animals; D005269:Femur / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D007273:Injections, Intramuscular; D008297:Male; D009919:Orchiectomy; D010024:Osteoporosis / Q000188:drug therapy / Q000235:genetics*; D053245:RANK Ligand / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000008:administration & dosage* / Q000097:blood; D013977:Tibia / Q000187:drug effects / Q000378:metabolism
chemical_list: D053245:RANK Ligand; D013739:Testosterone
keywords: Bone; male; orchidectomy; osteoporosis; testosterone