2), as well as a significant increase in RANKL immunolabelling (Fig. 1). OVX/E2 group started to show a decreasing in OPG immunolabelling for osteoblasts and osteocytes.

OVX/O group presented expressive labelling against RANKL. Raloxifene administration caused a reduction in RANKL immunolabelling at 28 days and absence immunolabelling at 42 days. TRAP immunolabelling was kept intense to moderate for OVX/O and OVX/E2 groups respectively and reduced for the other groups, primarily for the OVX/RLX group (Fig. 3) (Table 1). Oestrogen deficiency systemically affects bone remodelling through OPG/RANKL signalisation during the Raf inhibitor events that modulates osteoclasts cellular differentiation and lymphocytes development. In the experiments realized in our laboratory, the osteoprotective effect of oestrogen in inhibits bone resorption is confirmed after Veliparib ic50 treating OVX rats with 17β-estradiol. Which increased bone mass in the middle third of the alveolar bone, however the action of raloxifene was not as pronounced as E2.11 and 12 The intense immunolabelling for RANKL

and TRAP observed in OVX animals showed the signalling action of the members of the tumour necrosis factor (RANKL) on osteoclastic responses (TRAP). The oestrogen deficiency following ovariectomy leds to a high bone turnover during the alveolar healing process after tooth extraction whilst, oestrogen and raloxifene treatments led to bone formation. However TRAP expression at 28 and 42 days post-extraction in OVX animals treated with raloxifene was very low, whilst this expression was more expressive in OVX animals treated with oestrogen. Our results suggest that raloxifene treatment may compensate the changes induced by ovariectomy reducing the number of pre-osteoclasts and mature osteoclasts. Studies have shown that oestrogen deficiency leads to an increase of osteocytes apoptosis in human beings13 check and in female rats14 and the osteocytes apoptosis can be reverted through oestrogen replacement therapy14 and 15 or through raloxifene therapy.16 Studies have suggested

an autocrine mechanism, through a Fas ligand (FasL), in which oestrogen-induced osteoclast apoptosis17 and a paracrine mechanism in which oestrogen affects osteoclast survival through FasL upregulation in osteoblast cells leading to pre-osteoclasts apoptosis,18 this may explain the osteoprotective function of oestrogen as well as of SERMs. However, Kawamoto et al.19 evaluated the effects of oestrogen deficiency state in osteoclastogenesis of the periodontal tissue at 7 postoperative days and did not find any difference in the number of osteoclasts between oestrogen replacement therapy and sham groups. The authors also observed a significant increase of TRAP expression at 14 postoperative days on OVX group compared to the others, these finding are in agreement to our findings.