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 degarelix-induced (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 orchidectomy and degarelix administration significantly lowered serum testosterone level, decreased whole body BMC, femoral BMA, femoral BMC, and femoral BMD (P < 0.05) compared with the SHAM group. However, no significant 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.
METHODS: Orchidectomized, adult male Sprague-Dawley rats were treated subcutaneously with 125 μg/kg/day and 250 μg/kg/day testosterone with or without flutamide (androgen receptor blocker) and finasteride (5α-reductase inhibitor) for seven (7) days. Following treatment completion, in vivo perfusion of vas deferens lumen was performed and changes in fluid secretion rate, pH and HCO3- content were measured with and without bafilomycin, a V-ATPase inhibitor. Rats were then sacrificed and vas deferens were harvested and subjected for V-ATPase A1 and B1/2 protein expression and distribution analysis by western blotting and immunohistochemistry, respectively.
RESULTS: In sham-operated and testosterone-treated orchidectomized rats, higher fluid secretion rate, which was not antagonized by bafilomycin but lower HCO3- content and pH which were antagonized by bafilomycin were observed when compared to orchidectomized-only and orchidectomized, testosterone-treated rats receiving flutamide or finasteride, respectively. Bafilomycin had no effect on fluid secretion rate, HCO3- content and pH in orchidectomized and testosterone-treated orchidectomized rats receiving flutamide and finasteride. V-ATPase A1 and B1/2 proteins were expressed at high levels in vas deferens and were highly distributed at the apical membrane of luminal epithelium and in muscle layer of this organ, mainly in sham and testosterone-treated orchidectomized rats.
CONCLUSIONS: V-ATPase is involved in acidification of vas deferens fluid under testosterone influence.