Immunolocalization of sclerostin synthesized by osteocytes in relation to bone remodeling in the interradicular septa of ovariectomized rats

Abstract

This study aimed to elucidate whether estrogen deficiency would affect the synthesis of an osteocyte-derived factor, sclerostin, in the mesial region of alveolar bone. Eight 9-week-old Wister female rats were ovariectomized (OVX), and the other eight rats were Sham-operated (Sham). After 4 weeks, the interradicular septa of mandibular first molar were embedded in paraffin, and then, were histochemically examined. Sclerostin-positive osteocytes were located in a superficial layer of the mesial region of Sham bone, while the OVX mesial region showed a lesser presence of the sclerostin-reactive osteocytes. There was no significant difference in the distribution of estrogen receptor  and TUNEL-positive cells in either Sham or OVX groups. Meanwhile, the Sham mesial region demonstrated many osteoclasts, but the OVX specimens showed numerous osteoclasts in association with intense immunolabeling of the receptor activator of the nuclear factor kB ligand. Complex meshwork of cement lines was seen consistent with irregularly-distributed osteocytic lacunar-canalicular system in the OVX mesial region, compared with those of the Sham specimens. In conclusion, estrogen deficiency appears to inhibit osteocytes for sclerostin synthesis in the mesial region of the interradicular septum, mediated by accelerated bone remodeling, rather than by directly effecting osteocytes. words

Receptor Activator of Nuclear Factor‐κB Ligand and Sclerostin Expression in Osteocytes of Alveolar Bone in Rats With Ligature‐Induced Periodontitis

“…2) The anti-mouse sclerostin antibody was identical to that used in other studies using rat models. 20,38 This and previous studies showed weak sclerostin labeling of osteocytes in normal periodontium. However, in another study, normal periodontium of mice showed strong sclerostin expression in osteocytes using anti-mouse sclerostin antibody.…”

“…1) Increased RANKL‐positive cells, including PDL cells, osteoblasts, and inflammatory cells, were found in the PDL area before day 10 (data not shown); however, the relative contribution of RANKL sources between those cells and osteocytes was not determined. 2) The anti‐mouse sclerostin antibody was identical to that used in other studies using rat models 20,38 . This and previous studies showed weak sclerostin labeling of osteocytes in normal periodontium.…”