Equol exerts a protective effect on postmenopausal osteoporosis by upregulating OPG/RANKL pathway

Area of Science:

• Endocrinology
• Bone Biology
• Pharmacology

Background:

• Postmenopausal osteoporosis (PMOP) is primarily caused by estrogen deficiency.
• Phytoestrogens, like soy isoflavones (SI), can improve PMOP, with Equol (Eq) being a potent metabolite.
• Equol exhibits stronger estrogenic activity and a more stable structure than its parent compounds, yet its therapeutic effects on PMOP are understudied.

Purpose of the Study:

• To investigate the therapeutic potential of Equol (Eq) in treating postmenopausal osteoporosis (PMOP).
• To elucidate the underlying mechanisms through which Equol exerts its effects on bone health.

Main Methods:

• In vitro studies utilized osteoblast-like cells (ROS1728) treated with Equol (Eq) or estradiol (E2) to assess proliferation, apoptosis, and cell cycle.
• Quantitative real-time PCR (qRT-PCR) and Western blot (WB) analyzed the OPG/RANKL signaling pathway, with RNA silencing used to identify Equol's receptors.
• A rat model of PMOP was established and treated with Equol or estradiol to validate in vitro findings.

Main Results:

• Equol dose-dependently promoted osteoblast proliferation, inhibited apoptosis, and increased S and G2/M phase cell populations.
• Equol upregulated osteoprotegerin (OPG) and the OPG/RANKL ratio in osteoblasts, primarily through the Estrogen Receptor beta (ERβ).
• In vivo, Equol improved femur microstructure and bone mineral density (BMD) in PMOP rats, mirroring estradiol's effects, and modulated key bone metabolism markers.

Conclusions:

• Equol demonstrates a protective effect against postmenopausal osteoporosis.
• The mechanism involves Equol binding to ERβ and upregulating the OPG/RANKL pathway.
• Equol represents a potential therapeutic agent for PMOP.