Potential Benefits of Annatto Tocotrienol in Glucocorticoid Induced Osteoporosis: An Animal Study

Abstract

Long-term glucocorticoid treatment induces oxidative stress that cause osteoporosis is an antioxidant and has protective effects against free radical associated diseases. Annatto tocotrienol is a tocopherol free tocotrienol mixture. The purpose of this study was to determine the effects of annatto tocotrienol against glucocorticoid-induced osteoporosis. 32 adult male Sprague-Dawley rats were used in this study. 16 rats were adrenalectomized and divided into two groups; Adrx+Dexa and Adrx+Dexa+ATT and were administered with intramuscular injection of dexamethasone 120 μg/kg/ day. Eight rats underwent sham procedure and the other 8 serves as baseline group. The Adrx+Dexa group was given vehicle palm olein 0.1 ml/kg/day orally while Adrx+Dexa+ATT group was supplemented with annatto tocotrienol 60 mg/ kg/day. The sham operated rats were given vehicle palm olein 0.05 ml/kg/day by intramuscular injection and 0.1 ml/ kg/day orally. The treatments were given for two months before the rats were euthanized. The femurs were tested for biomechanical strength and analyzed for bone histomorphometry. The results showed that long-term glucocorticoid treatment increased, bone resorption marker (CTX), lipid peroxidation; and decreased superoxide dismutase (SOD) activity with no significant changes to serum osteocalcin. Bone biomechanical strength was compromised with reduction in structural, static and dynamic parameters of bone histomorphometry. Annatto tocotrienol supplementation had maintained lipid peroxidation, CTX level, SOD activity and protected bone histomorphometric parameters and biomechanical strength. The results of this study suggested that annatto tocotrienol may have protective effects against osteoporosis induced by glucocorticoids and may be used as prophylaxis for patients on long term glucocorticoid therapy.