Abstract
Background: Exercise and vitamin D can improve bone density by reducing bone loss. Growth factors such as IGF-I and IGFBP-3 are appeared to increase bone turnover in response to mechanical load, and free radicals attenuate the release of these growth factors. Objectives: We assessed the effect of concurrent aerobic training and cholecalciferol administration along with hydrogen peroxide injection on the levels of IGF-I and IGFBP-3 expression in the bone tissue of rats. Methods: Thirty-six adult Wistar rats were randomized into six groups (n = 6), including healthy control, sham, hydrogen peroxide (H2O2), H2O2 + aerobic training, H2O2 + cholecalciferol, and H2O2 + aerobic training + cholecalciferol. The rats were intraperitoneally administered with one mmol/kg. Body weight (BW) of H2O2 three times a week on even days and 0.5 μg/kg.bw of cholecalciferol daily. Aerobic training (at a speed of 4 - 20 m/min, for 20 - 60 minutes) was performed five days/w for eight weeks. The expression of IGF-I and IGFBP-3 was measured by real-time (RT)-PCR. Data were analyzed using the independent t-test, two-way ANOVA (exercise × vitamin D), and Bonferroni’s post-hoc test in SPSS 26 at the significance level of P ≤ 0.05. Results: The results showed that H2O2 significantly reduced the gene expressions of IGF-I (P = 0.001) and IGFBP-3 (P = 0.001) in the bone tissue. Also, exercise and vitamin D augmented the expression of IGF-I (P = 0.008) and IGFBP-3 (P = 0.0001) as post-hoc analysis showed that aerobic training had the greatest effect on the expression of IGF-I and IGFBP-3 (P < 0.05). In addition, the amplifying effects of aerobic training and cholecalciferol on the gene expressions of IGF-I and IGFBP-3 were also remarkable (P < 0.1). Conclusions: The mechanical load created by aerobic training exerted the greatest augmenting effect on the gene expression of IGF-I and IGFBP-3. Moreover, the interactive effect of aerobic training and cholecalciferol was also significant.