Resveratrol promotes osteoblastic differentiation in a rat model of postmenopausal osteoporosis by regulating autophagy

Objective: Resveratrol is a natural polyphenolic compound that ameliorates postmenopausal osteoporosis by activating the estrogen receptor. Research has shown that resveratrol exhibits some type of estrogen receptor agonist activity, reducing the risk of breast cancer. However, its mechanism of action remains largely unknown. This study aims to investigate the effect of resveratrol on osteoblastic and osteoclastic differentiation and its potential role in the regulation of autophagy.

Methods: Sprague Dawley (SD) rats underwent ovariectomies (OVX) and were administered resveratrol (at 10, 20 or 40 mg/kg/d) for 8 weeks. The calcium content and the bone mineral density (BMD) were measured in the lumbar vertebrae (L3) and the right distal femur-tibia bone region. The osteoblasts and osteoclasts were isolated from rat lumbar vertebrae by enzyme digestion and bone marrow induction, respectively. The cells were then cultured with resveratrol in combination with bafilomycin or leupeptin to inhibit or activate autophagy, respectively. Western blotting was used to assess the differentiation markers and autophagy-related genes in the osteoblasts and osteoclasts.

Results: Compared to the sham group, the bone calcium content and BMD were significantly decreased in the OVX group (p < 0.05), while resveratrol attenuated these in a dose-dependent manner. In the osteoblasts, vascular endothelial growth factor (VEGF), and alpha-1 type I collagen (COL1A1) were markedly decreased, and in osteoclasts, the receptor activator of nuclear factor-κB ligand (RANKL) was increased in the OVX group, while resveratrol reversed this pattern in a dose-dependent manner. The inhibition of autophagy in osteoblasts and its activation in osteoclasts was observed in the OVX group. However, with resveratrol, this was reversed in a dose-dependent manner.

Conclusion: Overall, resveratrol promotes osteoblastic differentiation and suppresses osteoclastic differentiation in a rat model with postmenopausal osteoporosis by regulating autophagy.