Proton Magnetic Resonance Spectroscopy-Detected Changes of Marrow Fat Content in a Rabbit Model of Osteoporosis Treated With Epigallocatechin-3-Gallate.

OBJECTIVE: The aim of this study was to longitudinally evaluate the changes in marrow fat content of ovariectomized (OVX) rabbits treated with epigallocatechin-3-gallate (EGCG) using proton magnetic resonance spectroscopy (H-MRS).

METHODS: Thirty-six female New Zealand rabbits were equally divided into sham operation, OVX controls, and OVX treated with EGCG (intraperitoneally, 1.8 mg/kg) for 5 months. Marrow fat fraction by H-MRS and bone density by peripheral quantitative computed tomography were determined at 0, 3, and 5 months. Serum biomarkers and marrow adipocytes were determined at the end of experiment.

RESULTS: Estrogen deficiency increased marrow fat content in a time-dependent manner, with a variation of marrow fat fraction (FF) (+25.3%) at month 3 from baseline, and it was maintained until month 5 (+66.6%, all P < 0.001). In comparison with the sham-operated controls, adipocytes density, size, and percentage of adipocytes area in the OVX controls increased by 62.9%, 44.4%, and 178%, respectively (all P < 0.05). These OVX-induced pathological changes were partly reversed by EGCG treatment. In addition, EGCG treatment reduced bone turnover and increased bone density of OVX rabbits.

CONCLUSIONS: Epigallocatechin-3-gallate exhibits an anabolic effect on osteoporotic bone by concomitantly rescuing bone mass and mitigating marrow adiposity. H-MRS appears to be a useful tool for monitoring osteoporosis-related treatments.