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Title: Effect of long-term green tea polyphenol supplementation on bone architecture, turnover, and mechanical properties in middle-aged ovariectomized rats

Author
item SHEN, CHWAN-LI - Texas Tech University
item SMITH, BRENDA - Oklahoma State University
item Cao, Jay
item LI, JILIANG - Indiana University-Purdue University
item SONG, XIAO - University Of Georgia
item NEWHARDT, MARIA - Oklahoma State University
item CORRY, KYLIE - Indiana University-Purdue University
item TOMISON, MICHAEL - Texas Tech University
item TANG, LILI - University Of Georgia
item WANG, JIA-SHENG - University Of Georgia

Submitted to: Calcified Tissue International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2018
Publication Date: 11/9/2018
Citation: Shen, C., Smith, B., Cao, J.J., Li, J., Song, X., Newhardt, M.F., Corry, K.A., Tomison, M.D., Tang, L., Wang, J. 2018. Effect of long-term green tea polyphenol supplementation on bone architecture, turnover, and mechanical properties in middle-aged ovariectomized rats. Calcified Tissue International. https://doi.org/10.1007/s00223-018-0489-y.
DOI: https://doi.org/10.1007/s00223-018-0489-y

Interpretive Summary: Studies have demonstrated that moderate consumption of green tea polyphenols (GTP) is beneficial to bone health. In this study, we investigated the effects of different dosages of GTP supplementation in drink water for up to 6 months in middle-aged, ovariectomized (OVX) rats. We found that GTP supplementation, especially at higher dosage, improved bone mineral density (BMD) and structural parameters at both trabecular and cortical bone, as well as bone mechanical properties of OVX animals. GTP supplementation dose-dependently suppressed bone turnover in OVX rats, mainly at the endocortical surface, for both trabecular and cortical bones. Our data provide the scientific justification for long-term GTP supplementation in postmenopausal women with osteopenia and/or osteoporosis.

Technical Abstract: Introduction: We investigated the effects of 6-month green tea polyphenols (GTP) supplementation on bone architecture, turnover, and mechanical properties in middle-aged ovariectomized (OVX) rats. Methods: Female rats were sham-operated (n=39, 13/group) or OVX (n=143, 13/group). Sham-control and OVX-control rats (n=39) receiving no GTP were assigned for sample collection at baseline, 3, or 6 months. The remaining OVX rats (n=104) were randomized to 0.15%, 0.5%, 1%, and 1.5% (g/dL) GTP for 3 or 6 months. Blood and bone samples were collected. Results: Relative to the OVX-control group, GTP (1% and 1.5%) lowered serum procollagen type 1 N-terminal propeptide at 3 and 6 months, C-terminal telopeptides of type I collagen at 3 months, and insulin-like growth factor-I at 6 months. GTP did not affect bone mineral content and density. At 6 months, no dose of GTP positively affected trabecular bone volume based on microCT, but a higher cortical thickness and improved biomechanical properties of the femur mid-diaphysis was observed in the 1.5% GTP-treated group. At 3 and 6 months, GTP (0.5%, 1% and 1.5%) had lower rates of trabecular bone formation and resorption than the OVX-control group, but the inhibitory effects of GTP on periosteal and endocortical bone mineralization and formation at the tibial midshaft were only evident at 3 months. Conclusions: GTP at higher doses suppressed bone turnover in the trabecular and cortical bone of OVX rats and resulted in improved cortical bone structural and biomechanical properties, although it was not effective in preventing the ovariectomy-induced dramatic cancellous bone loss.