Efficacy and Mechanisms of Oleuropein in Postmenopausal Osteoporosis

Abstract

Background. Postmenopausal osteoporosis (PMOP) has a supernal morbidity rate in elderly females. Objective. To appraise the effects of oleuropein on bone densitometry, bone metabolic index, oxidative stress, and inflammatory index in PMOP. In addition, the mechanism of olive bittersweet preventing bone loss was explored. Methods. We grouped 80 salubrious female Sprague-Dawley rats into four teams: (1) sham operation team (sham, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mi>N</a:mi> <a:mo>=</a:mo> <a:mn>20</a:mn> </a:math> ), (2) ovariectomy (OVX, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"> <c:mi>N</c:mi> <c:mo>=</c:mo> <c:mn>20</c:mn> </c:math> ), (3) castrated mice fed with oleuropein (OVX+ole, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"> <e:mi>N</e:mi> <e:mo>=</e:mo> <e:mn>20</e:mn> </e:math> ), and (4) castrated mice fed with estrogen (OVX+E2, <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" id="M4"> <g:mi>N</g:mi> <g:mo>=</g:mo> <g:mn>20</g:mn> </g:math> ). The ovariectomized SD rats were continuously raised with 200 μg/kg/dose of oleuropein. Bone mineral density and bone metabolism indexes were recorded. In order to assess the effectiveness of oleuropein on osteopenia, an enzyme-linked immunosorbent assay (ELISA) was devoted to examining the bone marrow indexes. The bone metabolism standards of PMOP rats were appraised by assessing serum levels of calcium, alkaline phosphatase (ALP), phosphorus, malondialdehyde (MDA), and nitrate content by experimental detection methods and levels of osteoclastogenesis inhibitory factor (OPG) and receptor activator for nuclear factor-κB ligand (RANKL) by ELISA. The OPG-RANK-RANKL signal passage was examined by Western blot (WB). We measured bone mineral density using dual-energy X-rays. Results. Our animal experimental results indicated that oleuropein could significantly improve the bone mineral density of ovariectomized SD rats. In the meantime, it could reduce ending interleukin-6 (IL-6), malondialdehyde (MDA), nitrate, alkaline phosphatase (ALP), and phosphorus (P) serum concentration and would not affect Ca2+ concentration. In cell experiments, oleuropein also can promote the proliferation of osteoblasts. Furthermore, it can promote the expression of OPG protein and mRNA. In reverse, it inhibits the expression of RANKL protein and mRNA. Conclusion. Oleuropein can not only improve the inflammatory and oxidative indexes of castrated rats but also prevent osteoporosis. Oleuropein avoids bone resorption by regulating OPG/RANKL expression.