The Effect Of (-)-epigallocatechin-3-gallate In Preventing Bone Loss In Ovariectomized Rats And Possible Mechanisms Study

Objective:To study the effect of (-)-Epigallocatechin-3-gallate (EGCG) in preventing bone lossin ovariectomized (OVX) female rats, the effect of giving EGCG intraperitoneally versusgiving from gavage, and to explore the underlying possible mechanisms.Methods:Fifty-five3-month old femal Sprague-Dawley Rats (SD rats) were weighed anddivided into the following5groups as no statistical significance reached among all thegroups: group A,15rats, intraperitoneally giving EGCG for consecutive12weeks startedfrom3days after OVX; group B,10rats, intraperitoneally giving EGCG for consecutive6weeks started from7weeks after OVX; group C,10rats, giving EGCG from gavage forconsecutive12weeks started from3days after OVX; group D,10OVX rats withoutEGCG intervention, OVX; group E,10rats, sham-operated group,SHAM.12weeks afterOVX, rats were killed by excessive anesthesia, and bilateral tibia and femur were attainedand prepared for:1, Micro-CT scanning, BMD and bone morpological parameterscalculation;2,3-point bending test;3, HE staning, and immunohistological study testingthe expression of Sema4D.Results:Bone morphological parameters：Bone mineral density (BMD) and trabecular bonevolume/total volume (BV/TV) of the SHAM group (group E) was significantly higherthan the other4OVX operated groups, and both BMD and BV/TV of group A wassignificantly higher than the OVX group (group D)(P<0.05). Trabecular seperation (Tb.Sp)from the SHAM group (group E) was significantly lower than the other4OVX operatedgroups, and Tb.Sp of group A was significantly lower than the OVX group (group D)(P<0.05). Trabecular thickness (Tb.Th) from the SHAM group (group E) was significantlyhigher than the other4OVX operated groups (P<0.01), and no statistical significance was observed among the other4OVX operated groups. No statistical significance was detectedamong all groups of trabeluar number (Tb.N)(P>0.05). Results from3-point bending testshowed no statistical significance among all the groups of bending displacement anduntimate bending stress (P>0.05). Bone histological study indicated that trabecular bonewas more dense, and had more numbers in the SHAM group (group E), while the OVXgroup (group D) had a sparser trabecular bone. The bone morphological status of group A,B and C were between the OVX group (group D) and the SHAM group (group E).Immunohistological study demonstrated that Sema4D was expressed more as the percentof brown stained area was more in the OVX group (group D) than the other groups. Nostatistical significance detected between group A and SHAM group (P>0.05).Conclusions:.1, EGCG can mitigate the bone loss process of female OVX rats, and at the dose of10mg/kg/day, giving earlier is likely to be better than giving later, but the early applicationof EGCG cannot completely prevent the bone loss precess in OVX rats;2, Based on the dose of10mg/kg/day, EGCG giving from intraperitoneal injection islikely to be more evident than feeding from gavage on preventing bone loss in femaleOVX rats;3, The expression of Sema4D is significantly higher in the OVX rats than the normalrats, and EGCG can reduce the expression of Sema4D in the bone tissue of OVX rats.