Long-term glucocorticoid treatment induces oxidative stress that leads to substantial changes in bone mass, bone structure, mechanical properties and formation of new bone. Free radicals are toxic to osteoblasts and are associated with bone resorption by osteoclasts. Tocotrienol is a type of vitamin E which is an antioxidant and has protective effects against free radical associated diseases. The purpose of this study was to determine the protective effects of palm tocotrienol against glucocorticoid-induced osteoporosis. 40 adult male Sprague-Dawley rats were used in this study. 20 rats were adrenalectomised and replaced with 120 μg/kg/day intramuscular dexamethasone injection. 10 rats were supplemented with palm tocotrienol 60mg/kg/day and another 10 were given apha tocopherol 60 mg/kg/day orally. The control group which consisted of 10 rats was given vehicle palm olein 0.1 ml/kg/day by oral gavage. 10 rats were sham operated and given vehicle palm olein 0.05 ml/kg/day by intramuscular injection and 0.1ml/kg/day orally. The treatments were given for two months before the rats were sacrificed. The right femoral bones were tested for biomechanical strength and the left femoral bones were analysed for cellular parameters of bone histomorphometry. The results showed that long-term glucocorticoid treatment had caused a significant decreased in the osteoblast surface (Ob.S). The Osteoid Volume/Bone Volume (OV/BV) and the Osteoid Surface /Bone Surface (OS/BS) were significantly increased. Supplementation of palm tocotrienol had significantly maintained the Ob.S and the OS/BS equivalent to the sham operated rats. Palm tocotrienol also maintained the biomechanical strength of the bones. This may be due to the antioxidant effect of palm tocotrienol that had protected osteoblasts against the toxic effect of glucocorticoids. This resulted in stronger bone. The results of this study suggested that palm tocotrienol may have protective effects against the adverse effects of excess glucocorticoids and may be used as a supplement for patients on long-term glucocorticoid therapy.
Disclosure: The authors declared no competing interests. This research was supported by a grant from University Kebangsaan Malaysia, code: FF-349-2011.