1325 Int. J. Morphol., 37(4):1325-1330, 2019. Influence of Green Tea Extract with Different Concentrations of Epigallocatechin Gallate on Calvaria Bone Repair of Ovariectomized Rats Influencia del Extracto de Té Verde con Diferentes Concentraciones de Galato de Epigalocatequina sobre la Reparación Ósea de Calvaria de Ratas Ovariectomizadas Luana Cristina de Freitas; Luiz Gustavo de Sousa; Guilherme Luciano Leite; Priscilla Hakime Scalize; Dimitrius Leonardo Pitol; Mariah Acioli Righetti; Vitória Ricardo; Edneia Corrêa de Mello; Karina Fittipaldi Bombonato-Prado; Simone Cecilio Hallak Regalo & Selma Siessere FREITAS, L. C.; SOUSA, L. G.; LEITE, G. L.; SCALIZE, P. H.; PITOL, D. L.; RIGHETTI, M. A.; RICARDO, V.; MELLO, E. C.; BOMBONATO-PRADO, K. F.; REGALO, S. C. H. & SIESSERE, S. Influence of green tea extract with different concentrations of epigallocatechin gallate on calvaria bone repair of ovariectomized rats. Int. J. Morphol., 37(4):1325-1330, 2019. SUMMARY: Impairing osteoporosis progression is a challenge, and recently the role of antioxidants has been associated to bone metabolism. Green tea extract is rich in catechins, especially epigallocatechin gallate (EGCG), which may help control osteoporosis damage in bone tissue. This investigation evaluated the efficacy of green tea ingestion containing different concentrations of EGCG in calvaria bone repair of ovariectomized rats. Wistar rats (n=15) were ovariectomized and divided into 3 groups: ovariectomized (OVX), ovariectomized + GTE 15 % EGCG (OVX/GTE15), and ovariectomized + GTE 94 % EGCG (OVX/GTE94). Green tea extract was administered by gavage in the concentration of 50 mg/kg and sham group (n=5) received water. Bone defects were performed in the calvaria 60 days after ovariectomy followed by 4 weeks until euthanasia. Bone samples were collected to perform qualitative and quantitative histological analysis of bone formation. Data obtained were submitted to normality and ANOVA statistical test for p<0.05. The mean values of neoformed bone for Sham, OVX, OVX/GTE15 and OVX/GTE94 were respectively: 21.11 ± 3.91; 19.92 ± 2.20; 33.05 ± 1.26 e 34.75 ± 0.54 (p<0.05). Results show that continuous ingestion of green tea extract immediately after ovariectomy shows positive effects in the prevention of bone loss in osteoporosis, even with low concentrations of EGCG. KEY WORDS: Tea; Catechin; Osteoporosis; Bone; Rats. INTRODUCTION Healthy bone tissue is in constant remodeling, nevertheless, when resorption overwhelms formation, osteoporosis may occur (Appelman-Dijkstra & Papapoulos, 2016). The etiology of this disease is multifactorial, and among them oxidative stress has been shown to interfere in bone remodelation because of free radicals accumulation which are not normally eliminated, resulting in loss of biological functions and oxidative damage to cells and tissues (Domazetovic et al., 2017). Researches have been demonstrating that control and treatment of osteoporosis might be reached with antioxidant ingestion, for they participate of free radical control protecting healthy cells from oxidative stress. Antioxidants can be found in vegetables, fruits (Peluso & Serafini, 2017) and also in green tea (Camellia sinensis L.), which is a po- pular beverage around the world with positive antimutagenic, antiproliferative, anticancerigen and antioxidant properties. These properties are given by polyphenols contained in green tea extract (GTE), composed mainly by epicatechin (EC), epigallocatechin (EGC), epicatechin-3-gallate (GEC) and epigallocatechin gallate (EGCG). EGCG is the most abundant (Sharifzadeh et al., 2017) and has been associated to osteogenesis (Jin et al., 2015). Green tea extract might be a good alternative in the treatment and prevention of osteoporosis, promoting positive effects on osteoblasts, eliminating free radicals as well as diminishing inflammations (Vester et al., 2014). Department of Basic and Oral Biology, School of Dentistry of Ribeirão Preto University of São Paulo, Ribeirão Preto, São Paulo, Brazil. We thank FAPESP (São Paulo Research Foundation - Process No. 2016/08720-0), CNPq (National Council for Scientific and Technological Development) and National Institute and Technology - Translational Medicine (INCT.TM) for financial support.