Green tea (Camellia sinensis) aqueous extract alleviates postmenopausal osteoporosis in ovariectomized rats and prevents RANKL-induced osteoclastogenesis in vitro

Abstract

BackgroundGreen tea (Camelliasinensis [L.] Kuntze) belongs to the plant family Theaceae and is mainly distributed in East Asia, the Indian subcontinent and Southeast Asia. This plant has been proven to be beneficial to human health, and green tea is the second most consumed beverage in the world after water. However, until now, the effect of green tea aqueous extract (GTE) upon postmenopausal osteoporosis has remained unclear. In this study, we investigated the therapeutic effects of GTE on estrogen deficiency-induced osteoporosis and explored the possible mechanisms in vivo and in vitro.Materials and methodsOvariectomized (OVX) female rats were orally administered with GTE at doses of 60, 120, and 370 mg kg−1 for 13 consecutive weeks. The biochemical parameters, bone gla protein, alkaline phosphatase, acid phosphatase, estrogen, interleukin-1β, and interleukin-6 in blood samples were detected, and histological change in bones was analyzed by hematoxylin and eosin staining. Meanwhile, the mechanisms of GTE on osteoclast formation were explored in RAW 264.7 cells induced by receptor activation of the nuclear factor kappa B ligand (RANKL).ResultsThe results showed that GTE could increase bone mass and inhibit trabecular bone loss in OVX rats. Furthermore, real-time quantitative reverse transcription polymerase chain reaction analysis from in vitro experiments also showed that GTE reduced the mRNA expression of osteoclast-associated genes such as cathepsin K (cath-K), c-Fos, matrix metalloproteinase 9, nuclear factor of activated T cells cytoplasmic 1 (NFATc1) and tartrate-resistant acid phosphatase. In addition, GTE caused a reduction in the protein levels of NFATc1, c-Fos, c-src and cath-K.ConclusionEvidence from both animal models and in vitro experiments suggested that GTE might effectively ameliorate the symptoms of osteoporosis in OVX rats and inhibit RANKL-induced osteoclast-specific gene and protein expression.

White Tea Reduced Bone Loss by Suppressing the TRAP/CTX Pathway in Ovariectomy-Induced Osteoporosis Model Rats

“…Increased levels of TRAP and CTX were shown in OVX rats [Solberg et al, 2014]. A previous study showed that tea consumption in rats with OVX-induced bone loss can suppress the level of TRAP, one of the osteoclast-specific genes [Wu et al, 2018]. Investigation of the effect of WT on serum TRAP levels in OVX rats in our study is the first in the literature.…”

“…Serum TRAP levels increased in the OVX rats with respect to the sham group but significantly decreased in the OVX + WT group. In a previous study, aqueous extract of green tea was shown to suppress RANKL-induced osteoclastogenesis in vitro, reducing TRAP gene expression because of this inhibition [Wu et al, 2018]. Similarly, black tea extracts were reported to reduce serum TRAP levels in the OVX rats [Das et al, 2009].…”

“…Osteoporosis is a multifaceted skeletal system disease characterized by decreased bone mass and mineral con- lovas et al, 2008]. Many studies are indicating a positive relationship between tea and bone health [Tomaszewska et al, 2018;Wu et al, 2018]. The positive effects are attributed to the efficacy of polyphenolic flavonoids in tea such as catechins (epicatechin, epigallocatechin and epicatechin-3-gallate) and the main flavonoid (-)-epiglocat-echin-3-gallate.…”

The Pharmacological Activity of Camellia sinensis (L.) Kuntze on Metabolic and Endocrine Disorders: A Systematic Review

“…Green tea extract (25, 50, and 100 µg/mL, 48 h) has shown to inhibit RANKL-induced osteoclast formation in the mouse macrophage-like cell line RAW264.7 related to NFATc1, cathepsin K, C-Fos, and MMP-9 gene levels reduction [103]. Moreover, the isolated compound gallocatechin gallate (oxidation product of epigallocatechin-3-gallate) at 10 µM concentration inhibited osteoclastogenesis more potently than epigallocatechin-3-gallate through gene and protein downregulation (TRAP, c-Src, β3-Integrin, cathepsin K, and MMP-9) and master transcriptional regulators downregulation (NFATc1 and c-Fos) in RAW264.7 cells [104].…”

Green Tomato Extract Prevents Bone Loss in Ovariectomized Rats, a Model of Osteoporosis

“…Identification of agents that helps bone loss prevention would have substantial effect on the development of treatments for osteoporosis. Earlier studies have proposed the possibility of a nutritional approach as an alternative for the prevention of postmenopausal osteoporosis [ 13 , 14 , 15 , 16 , 17 , 18 ].…”