The Protective Effect Of Inulin Fructan AMP1-1 From Atractylodes Macrocephala On Weightlessness-induced Bone Loss

When astronauts are exposed to space environment for a long time,weightlessness could induce bone calcium loss and bone matrix reduction,which lead to weightlessness-induced bone loss.Weightlessness-induced bone loss can not only cause the incidence of astronauts’fractures,but also have the characteristics of poor recovery after returning to the ground.This could affect the astronauts’space mission,and also seriously threatens their health.Therefore,it has become one of the important tasks of aerospace medicine to find a safe protective agent with high protective activity and few side effects.In this study,Atractylodes macrocephalon polysaccharides（AMP1-1）with anti-weightlessness bone loss activity was isolated and purified using activity tracking.GPC and monosaccharide composition analysis showed that its molecular weight was1.433 k Da,and it was composed of glucose and fructose.Analysis of GC-MS data found that its chain skeleton had two bond types,namelyα-D-glcp-（1→and→1）-β-D-fruf-2→.Combined with NMR data and the above test results concluded that AMP1-1 was an inulin type fructan and its structural formula isα-D-Glcp-1→（2-βD-Fruf-1）7.After studies of BALP activity in osteoblasts,it was determined that AMP1-1 had a significant protective effect on weightlessness-induced bone loss.In order to clarify the pathway of weightlessness-induced bone loss,this study used iTRAQ to analyze the femur of weightlessness-induced bone loss rat model.It was found that weightlessness could cause significant changes in oxidative stress response in rat femur.By further analyzing the interaction of differential proteins in oxidative stress response,it is revealed that the main change pathway in oxidative stress response is Nrf2-HO-1/antioxidant enzyme pathway.In order to figure out the regulatory effect of AMP1-1 on osteoblasts and osteoclasts,the co-culture system of primary osteoblasts and osteoclasts was treated by simulated weightlessness.By detecting MDA content,Nrf2 and HO-1 gene expression,antioxidant enzyme gene and enzyme activity in osteoblasts and osteoclasts,it was found that AMP1-1 could prevent cell membrane damage and decrease of antioxidant enzyme activity under weightlessness through Nrf2-HO-1pathway.In addition,q RT-PCR,ELISA and enzyme activity data of BALP and TRAP-5b revealed that AMP1-1 could also effectively inhibit the decrease of osteoblast osteogenic ability and the increase of osteoclast osteoclastic ability caused by simulated weightlessness.The study of HLS rat model confirmed that AMP1-1 has the activity of anti-weightlessness bone loss.By testing the biomechanical properties of femur,it was found that AMP1-1 could significantly improve the decline of femur elastic modulus,maximum strain,maximum stress,maximum load and energy absorption caused by the effect of weightlessness.Moreover,using Micro-CT to observe the microstructure of rat femur,which showed that AMP1-1 also had a significant protective effect on the damage of femur structure and its integrity caused by simulated weightlessness.Using ELISA to analyze bone turnover factor in serum of HLS rats,it was found that AMP1-1 could significantly inhibit the increase of bone turnover factorβ-CTX,TRAP-5b,ICTP,P1NP and BALP which induced by simulated weightlessness.In addition,bone formation and bone resorption in the femur of HLS rats were analyzed by q RT-PCR,ELISA and enzyme activity detection methods.Data indicate that AMP1-1 could significantly inhibit the reduction of bone formation and increase of bone resorption.Finally,AMP1-1 could regulate the inclination of bone metabolism towards osteogenesis was proved by analyzing RANKL/OPG.In this study,a fragment AMP1-1 of anti-weightlessness active was screened from Atractylodes macrocephalon polysaccharides and its chemical structure was identified asα-D-Glcp-1→（2-β-D-Fruf-1）₇.In addition,the protective pathway of AMP1-1 alleviate weightlessness-induced bone loss was that AMP1-1 could regulate the activity of osteoblasts and osteoclasts by activating Nrf2-HO-1 antioxidant enzyme pathway,which could promote bone formation and inhibit bone absorption.For this reason,the bone metabolism towards osteogenesis which to protect weightlessness-induced bone loss.This study laid a theoretical foundation for the prevention of weightlessness bone loss,and also expanded the application of Atractylodes macrocephala in the field of space medicine...