Effects of tocotrienol on osteocyte-mediated phosphate metabolism in high-carbohydrate high-fat diet-induced osteoporotic rats

[Display omitted] •Osteocytes act as mechanosensory cells to control bone remodelling.•Lower osteocyte numbers and higher empty lacunae are detected in bone loss.•Lower DMP1 and PHEX levels are detected in bone loss.•Longer treatment period is required to observe the changes in phosphate level. The potential of osteocyte-mediated phosphate homeostasis as a molecular link between metabolic syndrome and osteoporosis remains to be elucidated. This study investigated the osteocyte lacunar network, levels of osteocyte-specific molecules and phosphate in high-carbohydrate high-fat (HCHF) diet-fed osteoporotic rats with/without treatment of tocotrienol. The HCHF-fed rats had higher empty lacunae numbers, lower osteocyte numbers, dentin matrix acidic phosphoprotein 1 (DMP1), andphosphate-regulating gene with homologies to endopeptidase on the X chromosome (PHEX) levels than the normal rats. Treatment with 100 mg/kg annatto tocotrienol significantly reduced empty lacunae numbers in the HCHF-fed rats. No changes in osteocyte number, DMP1, and PHEX levels between the tocotrienol-treated and vehicle-treated HCHF rats. Bone and serum phosphate levels were similar across all the groups. In conclusion, there are reductions in osteocyte numbers and expression of osteocyte-specific molecules in the HCHF diet-induced osteoporotic rats, but these changes are not reversed by the treatment with tocotrienol.