Panax notoginseng saponins suppress radiation-induced osteoporosis by regulating bone formation and resorption

Abstract

Background: While radiation-based therapies are effective for treating numerous malignancies, such treatments can also induce osteoporosis.

Purpose: We assessed the antiosteoporotic properties of total saponins extracted from the leaves of Panax notoginseng (LPNS) in a mouse model of radiation-induced osteoporosis and in vitro.

Study design/methods: The bone mineral densities, the marker of bone formation and resorption, and inflammatory factors were measured in vivo. Cell proliferation and differentiation were detected in vitro.

Results: The results showed that bone mineral densities in irradiated mice administered LPNS were significantly increased compared to those in irradiated mice which had not received LPNS. LPNS attenuated the inflammation caused by irradiation, and significantly increased blood serum AKP activity, the mRNA levels of RUNX2 and osteoprotegerin, and the numbers of CFU-Fs formed by bone marrow cells collected from irradiated mice. In contrast, LPNS decreased the numbers of osteoclast precursor cells (CD117(+)/RANKL(+) cells and CD71(+)/CD115(+) cells) and the mRNA levels of TRAP and ATP6i. These results suggest that LPNS functions as a negative regulator of bone resorption. In vitro assays showed that LPNS promoted the differentiation of bone marrow mesenchymal stem cells and mononuclear cells into osteoblasts and osteoclasts, respectively, but had no effect on osteoclast activation.

Conclusion: These results demonstrate that LPNS has significant antiosteoporotic activity, which may warrant further investigations concerning its therapeutic effects in treating radiation-induced osteoporosis.

Keywords: Antiosteoporotic; Osteoblast; Osteoclast; Radiation; Total saponins of Panax notoginseng leaves.