OBJECTIVE: This study aimed to determine the effectiveness of annatto-tocotrienol on the bone turnover markers and bone histomorphometry in a model of male osteoporosis induced by buserelin (a GnRH agonist).
METHODS: Forty-six three-months-old male Sprague-Dawley rats (three months old; 300-350 g) were randomly divided into six groups. The baseline control group (n = 6) was sacrificed at the onset of the study. The normal control group (n = 8) received corn oil (the vehicle of tocotrienol) orally daily and normal saline (the vehicle of buserelin) subcutaneously daily. The buserelin control (n = 8) received corn oil orally daily and subcutaneous buserelin injection 75 μg/kg/day daily. The calcium control (n = 8) received 1% calcium in drinking water and subcutaneous buserelin injection 75 μg/kg/day. The remaining rats were treated with two different treatments, i.e., (1) oral annatto tocotrienol at 60 mg/kg/day plus subcutaneous buserelin injection 75 μg/kg/day (n = 8); (2) oral annatto tocotrienol at 100 mg/kg/day plus subcutaneous buserelin injection 75 μg/kg/day (n = 8). The rats were injected with calcein twice before being sacrificed to label the bones. The rats were euthanized, and their blood and right femur were harvested at the end of the treatment for bone turnover markers and bone histomorphometry examination.
RESULTS: Both serum osteocalcin and C-telopeptide of type 1 collagen were not significantly different between treated groups and buserelin control (P > 0.05). The buserelin control group had a significantly lower bone volume and higher eroded surface compared with the normal control group (P buserelin control (P buserelin control (P
Methods: Forty-six male Sprague Dawley rats aged 3 months were randomized into six groups. The baseline control (n=6) was sacrificed at the onset of the study. The normal control (n=8) received corn oil (the vehicle of tocotrienol) orally daily and normal saline (the vehicle of buserelin) subcutaneously daily. The buserelin control (n=8) received corn oil orally daily and subcutaneous buserelin injection (75 µg/kg) daily. The calcium control (n=8) was supplemented with 1% calcium in drinking water and daily subcutaneous buserelin injection (75 µg/kg). The remaining rats were given daily oral annatto tocotrienol at 60 mg/kg (n=8) or 100 mg/kg (n=8) plus daily subcutaneous buserelin injection (75 µg/kg) (n=8). At the end of the experiment, the rats were euthanized and their blood, tibia, and femur were harvested. Structural changes of the tibial trabecular and cortical bone were examined using X-ray micro-computed tomography. Femoral bone calcium content and biomechanical strength were also evaluated.
Results: Annatto tocotrienol at 60 and 100 mg/kg significantly prevented the deterioration of trabecular bone and cortical thickness in buserelin-treated rats (P<0.05). Both doses of annatto tocotrienol also improved femoral biomechanical strength and bone calcium content in buserelin-treated rats (P<0.05). The effects of annatto tocotrienol were comparable to calcium supplementation.
Conclusion: Annatto tocotrienol supplementation is effective in preventing degeneration of the bone induced by buserelin. Therefore, it is a potential antiosteoporotic agent for men receiving androgen deprivation therapy.