Molecular mechanism of polygonatum sibiricum polysaccharide in the prevention and treatment of postmenopausal osteoporosis / 中国组织工程研究

ABSTRACT

BACKGROUND: Previous studies have found that polygonatum sibiricum polysaccharide (PSP) exhibits anti-osteoporosis effect, but its therapeutic effect in ovariectomized osteoporotic rats and the molecular mechanisms are poorly understood. OBJECTIVE: To investigate the effect of administration of PSP on the bone microstructure, bone mineral density as well as osteoblast- and osteoclast-related gene expression in rats. METHODS: Twenty-five infertile female Sprague-Dawley rats aged 3 months were randomly allotted into five groups (n=5 per group) sham operation (same volume normal saline), model, zoledronate (0.2 mg/kg?d), high-dose PSP (800 mg/kg?d) and medium-dose PSP (400 mg/kg?d) groups. All rats were subjected to ovariectomy except sham operation group. The administration was intragastrically given every 2 days beginning at 7 days after modeling and lasted 12 weeks. Then, the rats were sacrificed, and the uterus was weighed. The bilateral tibias were removed, one side for histomorphometric analysis by micro-CT, and the other one for RNA detection by qualified PCR. RESULTS AND CONCLUSION: Compared with the sham operation group, the rat body mass in the model group was significantly increased and the weight of uterus was significantly decreased (P < 0.05). Compared with the model group, zoledronate and high-dose PSP could significantly alleviate the excessive increase in body mass (P < 0.05). The bone mineral density in the model group was decreased by 63% compared with the sham operation group (P < 0.01), Compared with the model group, after 12-week high-dose PSP and zoledronate administration, the bone mineral density was increased by 44% and 38%, respectively (P < 0.01); the trabecular bone volume fraction and trabecular number rose significantly(P<0.05),while the trabecular separation decreased significantly(P<0.05).In vivo,PSP could significantly promote the expression levels of osteoblast-related genes (alkaline phosphatase, RUNX2, Col1a1 and osteocalcin), and significantly inhibit the expression levels of osteoblast-related genes (ACP5 and CTSK) (P < 0.05). These results imply that high-dose PSP can reduce bone loss and decrease of bone mineral density, improve the destruction of bone microstructure, as well as promote osteoblast-related genes but inhibit osteoclast-related gene mRNA expression in the ovariectomized rats.