Comparison of the Effects of Tocotrienol and Estrogen on the Bone Markers and Dynamic Changes in Postmenopausal Osteoporosis Rat Model

The standard treatment for postmenopausal osteoporosis is Estrogen Replacement Therapy (ERT) but it was associated with serious adverse effects such as breast cancer and cardiovascular disease. There is a need to find other alternatives for the treatment of post-menopausal osteoporosis. Vitamin E especially tocotrienol was shown to have anti-osteoporosis effects in many animal osteoporotic models but it has never been compared to estrogen. This study aimed to compare the effects of tocotrienol-enriched fraction to estrogen on the bone biochemical markers and dynamic histomorphometric changes using ovariectomised rats as the postmenopausal osteoporosis model. Thirty-two female Sprague-Dawley rats were randomly divided into groups of sham-operated (SHAM), ovariectomised control (OVC), ovariectomised+60 mg kg(-1) tocotrienol-rich fraction (OV+T) and ovariectomised+64.5 mu g kg(-1) of premarin (R) (OV+ERT). The rats were treated for two months and the serum osteocalcien and serum C-telopeptide of type 1 collagen (CTX) were measured using ELISA technique, while the femoral dynamic changes were analysed histomorphometrically. The CTX levels were found to be lowered compared to the pre-treatment levels for all the groups. Only the osteocalcin level of OV+ERT group was significantly reduced compared to its pre-treatment level. Dynamic histomorphometric analysis showed that both the OV+ERT and OV+T groups have lower single-labeled surface/bone surface (sLS) but higher double-labeled surface/bone surface (dLS), bone formation rate/bone surface (BFR) and mineral apposition rate (MAR) compared to the BC and OVC groups. The OV+T group showed better effects on most of the dynamic parameters compared to the OV+ERT group. Therefore, in postmenopausal osteoporosis model, tocotrienol-rich fraction has shown better bone protective effects than ERT.