The effects of fat-induced obesity on bone metabolism in rats.

OBJECTIVE: The aim of the current study was to investigate the effects of obesity, induced via a high-fat diet, on bone metabolism in rats.

METHODS: Two hundred healthy Wistar male rats aged 4 weeks were fed a standard diet and a high-fat diet. At specific time points (week 0, 4, 6, 8, and 10), plasma was collected to determine the levels of glucose and lipid metabolism. Additionally, enzyme-linked immunoassays were performed to determine the plasma levels of adipocyte and bone metabolism factors. Micro-CT imaging was used to determine the parameters of bone metabolism. At 10th week, immunohistochemistry evaluation of femoral bone samples was performed to determine the expression of adipocyte factors.

RESULT: Receptor activator of nuclear factor kB ligand (RANKL) was positively correlated with levels of triglyceride (TG), free fatty acids (FFA), and tumor necrosis factor alpha (TNF-α) (P<0.05), while receptor activator of the NF-κB (RANK) showed a positive correlation with TG, FFA, TNF-α and leptin (LPT) (P<0.05). CT imaging demonstrated that bone mineral density and trabecular thickness were elevated compared to controls before 6 weeks, but these values were found to be lower in rats fed a high fat diet in the following weeks (P<0.05). Immunohistochemistry showed that the expression of TNF-α, Interleukin- 6 (IL-6) and peroxisome proliferator activated receptor-γ (PPAR-γ) were increased and the expression of adiponectin (APN) were diminished in rats fed a high-fat diet compared to controls at 10 weeks (P<0.05).

CONCLUSION: With obesity intensifies, the release of FFA cause inflammation factor increase, resulting in bone parameters decreased.