This study aimed to compare the skeletal effect between GnRH agonist therapy and orchidectomy in male rats assessed using serum turnover markers and bone histomorphometry. Three-month-old male Sprague-Dawley rats (n = 46) were divided into three experimental arms, baseline, buserelin, and orchidectomy. In the buserelin arm, the rats received a daily subcutaneous injection of either normal saline or buserelin acetate at 25 µg/kg or 75 µg/kg. In the orchidectomy arm, the rats were either sham-operated or orchidectomized. The rats were euthanized after the three-month treatment. Blood was collected for the evaluation of bone turnover markers. Femurs were harvested for bone histomorphometry examination. A significant increase in serum C-telopeptide of type 1 collagen was observed in the orchidectomized group compared with the sham group (p < .05). Structural histomorphometry analysis showed that both buserelin (25 µg/kg and 75 µg/kg) and orchidectomy significantly decreased the trabecular bone volume, number and significantly increased trabecular separation in rats compared with their respective controls (p < .05). Osteoclast number and eroded surface were significantly increased in both buserelin (25 µg/kg and 75 µg/kg) and orchidectomized group compared with their respective controls (p < .05). As a conclusion, buserelin causes deterioration of bone microarchitecture and increased bone resorption similar to orchidectomy after three months.
Keywords: Bone; gonadotropin-releasing hormone agonists; histomorphometry; male osteoporosis.