The Effects of Tocotrienol and Lovastatin Co-Supplementation on Bone Dynamic Histomorphometry and Bone Morphogenetic Protein-2 Expression in Rats with Estrogen Deficiency

Abstract

Both tocotrienol and statins are suppressors of the mevalonate pathway. Supplementation of tocotrienol among statin users could potentially protect them against osteoporosis. This study aimed to compare the effects of tocotrienol and lovastatin co-supplementation with individual treatments on bone dynamic histomorphometric indices and bone morphogenetic protein-2 (BMP-2) gene expression in ovariectomized rats. Forty-eight female Sprague-Dawley rats were randomized equally into six groups. The baseline was sacrificed upon receipt. All other groups were ovariectomized, except for the sham group. The ovariectomized groups were administered orally daily with (1) lovastatin 11 mg/kg/day alone; (2) tocotrienol derived from annatto bean (annatto tocotrienol) 60 mg/kg/day alone; (3) lovastatin 11 mg/kg/day, and annatto tocotrienol 60 mg/kg/day. The sham and ovariectomized control groups were treated with equal volume of vehicle. After eight weeks of treatment, the rats were sacrificed. Their bones were harvested for bone dynamic histomorphometry and BMP-2 gene expression. Rats supplemented with annatto tocotrienol and lovastatin concurrently demonstrated significantly lower single-labeled surface, but increased double-labeled surface, mineralizing surface, mineral apposition rate and bone formation rate compared to individual treatments (p < 0.05). There was a parallel increase in BMP-2 gene expression in the rats receiving combined treatment (p < 0.05). The combination of annatto tocotrienol and lovastatin exerted either additively or synergistically on selected bone parameters. In conclusion, tocotrienol can augment the bone formation and mineralization in rats receiving low-dose statins. Supplementation of tocotrienol in statin users can potentially protect them from osteoporosis.

Tocotrienols for bone health: a translational approach

“…reported that γ‐tocotrienol supplementation benefits bone matrix production, as shown by increased osteoblasts per bone perimeter in the femur and spine, as well as increased mineral apposition rate (MAR) and BFR in the proximal tibia . Such osteoprotective effects of tocotrienols have been confirmed in an OVX‐induced bone loss model using γ‐tocotrienol, δ‐tocotrienol, palm tocotrienol (PTT) extract, and tocotrienol‐rich fraction . In general, tocotrienol supplementation improves bone strength by inducing bone formation and osteoblast activity, including osteoblast surface (Ob.S), Os.S/bone surface, osteoid surface/bone surface (OS/BS), osteoid volume/bone volume(OV/BV), trabecular thickness(Tb.Th), trabecular number (Tb.N), and BFR, as well as suppressing bone resorption, including trabecular separation (Tb.Sp), eroded surface (ES/BS), and osteoclastic activity (osteoclast surface (Oc.S)) .…”

Potential Role of Tocotrienols on Non-Communicable Diseases: A Review of Current Evidence

“…A study by Norazlina et al (2000) showed that oral administration of 30 or 60 mg/kg PVE maintained BMD, but only 60 mg/kg PVE maintained bone calcium content in ovariectomized rats [134]. In addition, oral administration of 60 mg/kg annatto-derived T3 was found to improved bone dynamic indices (increased dLS, MS, MAR, and BFR; and reduced sLS) in female rats with oestrogen deficiency [137]. So far, only pure γT3 and δT3 were examined for their bone-protective properties using ovariectomized female rats.…”

“…In the testosterone deficiency model, annatto T3 enhanced the expression of gene related to bone formation and osteoblast activity, such as alkaline phosphatase (ALP), β-catenin, and collagen type I alpha 1 (COL1α1) [147]. Treatment with T3 upregulated the expression of bone morphogenetic protein (BMP)-2, osteoprotegerin (OPG), Runx-2, OSX, vascular endothelial growth factor (VEGF)-α, and downregulated receptor activator of nuclear factor kappa-B ligand (RANKL) expression in the ovariectomized animals [137,138] and ovariectomized animals with fracture [166]. A recent in vitro study further supported that annatto T3 enhanced osteoblastic differentiation-related genes such as OSX, COL1α1, ALP, and OCN in murine MC3T3-E1 pre-osteoblastic cells [167].…”

<p>Annatto-Derived Tocotrienol Promotes Mineralization of MC3T3-E1 Cells by Enhancing BMP-2 Protein Expression via Inhibiting RhoA Activation and HMG-CoA Reductase Gene Expression</p>

“…28 Similarly, AnTT preserved trabecular bone microarchitecture in an animal model of osteoporosis induced by testosterone deficiency and metabolic syndrome. 37,42 Several limitations should be acknowledged in this study. We only studied the mevalonate pathway partially, focusing on the upstream (HMGR) and down-stream (RhoA) section of the pathway.…”

“…36 A previous animal study also showed that the combination of AnTT and lovastatin increased the expression of BMP-2 mRNA in the bones of ovariectomized rats. 37 This paper investigated the effects of annatto tocotrienol via BMP2 but it cannot be ruled out that it may act through other BMPs and transforming growth factor signaling in bone metabolism. [38][39][40][41] In this study, AnTT promoted osteoblast mineralization in MC3T3-E1 cells.…”