The effects of chemical castration with degarelix on bone turnover: Densitometric and biomechanics bone properties of male rats

Abstract

Background: Gonadotropin releasing hormone (GnRH) antagonists may cause chemical castration in males by suppressing the pituitary-gonadal axis, hence reducing testosterone level. There are limited data on the effects of degarelix, a newer series of potent and long acting GnRH antagonist on bone. Objectives: The current study aimed at determining the effects of degarelix on bone turnover, bone densitometry, and bone mechanical strength in male rats. Methods: Eighteen male Sprague-Dawley rats were randomly divided into sham (SHAM), orchidectomized (ORX), and degarelixinduced (DGX) groups. Chemical castration was performed by subcutaneous degarelix injection (2 mg/kg) at the scapular region. The rats were scanned for baseline bone mineral area (BMA), bone mineral content (BMC), and bone mineral density (BMD) using dual-energy x-ray absorptiometry (DXA). Following six weeks of experimental period, BMA, BMC, and BMD were measured again with DXA and blood was collected for testosterone and bone biomarkers (osteocalcin and C-terminal of type I collagen crosslink (CTX-1)) measurements. The rats were euthanized and femora were dissected for bone biomechanical strength analysis. Results: Bilateral orchidectomyanddegarelix administration significantly loweredserumtestosterone level, decreased wholebody BMC, femoral BMA, femoral BMC, and femoralBMD(P < 0.05) compared with theSHAMgroup. However, nosignificant changes were observed in bone biochemical markers and bone mechanical strength in all experimental groups. Conclusions: In conclusion, degarelix administration had comparable effects on bone as bilateral orchidectomy. Administration of degarelix provides an alternative method of inducing testosterone deficient-osteopenia in male rats without need for removing the testes.