Preliminary Study On The Relationship Between Simulated Weightlessness Muscle Atrophy And Spleen-asthenia Syndrome

BackgroundWeightlessness and simulated microgravity can lead to muscle atrophy in humans or rats. Chinese traditional medicine indicates that the spleen plays an important role in digestion and muscle, and is the source of generating QI and blood. Organs and muscles will be short of nutrition if the spleen asthenia occurs. Thus, muscle atrophy should belong to the deficiency of spleen-QI. A great deal of researches have indicated that the organism can emerge different degrees of signs of spleen asthenia, and the Chinese herb compound(main component: radix codonopsis, atractylodes macrocephala, tuckahoe) can reduce the symptom of deficiency of spleen-QI caused by weightlessness or simulated weightlessness in human beings and animals. Our previous investigation have shown that the soleus of SAS (spleen-asthenia syndrome) mice underwent obvious atrophy, and soleus fibers transformed from type I to type II. Therefore, the simulated weightlessness muscle atrophy may have some internal relationships with SAS, and some related researches have been paid close attention. According to the Chinese traditional medicine theory of "the spleen nourishing the muscles" and correlated findings in this realm, the comparative study was made between simulated weightlessness rats and SAS rats in the present study. The aim was set to provide scientific data for the dialectical study of weightlessness muscle atrophy, and we hope it could also provide some new ideas for drug prevention and cure insimulated weightlessness muscle atrophy.ObjectiveTail suspension was used to construct the model of simulated weightlessness; wasting and dissipating stagnant qi with intemperance of taking food were used to construct the model of spleen deficiency. The general sign, organ index and changes of digestion and absorption of the animals were observed. The Sijunzi decoction(SJZD) was chosen as a disproof to observe the affection of SJZD with different dose on SOL atrophy and fiber type of simulated weightlessness rat.Methods(1)Tail suspension was used to construct a model of simulated weightlessness; wasting and dissipating stagnant qi with intemperance of taking food were used to construct a model of spleen deficiency. Test animals were divided into three groups: control group(CON), spleen-asthenia syndrome group(SAS) and tail suspension group(TS). The general sign, organ index and changes of digestion and absorption of test animals were observed. The indexes including: body weight, temperature, liver index, spleen index, thymus index, D-xylose content and the activity of amylase in serum.(2)Medicine disproof: The SJZD was applied for intragastric administration to TS rats to observe it's affection on multiple physiological index of TS rats. The test animals were divided into five groups: CON, tail-suspending plus water group(TS+W), tail-suspending plus high dose SIZD group(TS+H), tail-suspending plus middle dose SJZD group(TS+M) and tail-suspending plus low dose SJZD group(TS+L). The indexes including: body weight, temperature, organ index, muscle wet weight(MWW), muscle wet weight to body weight(MWW/BW), cross sectional area (CSA) of type I and II fibers and relative proportion.Results(1)The changes of general physiological characters in simulated weightlessness rats SAS rats have typical symptoms of SAS, including dry hair, pale tail, depression, shutting eyes, gathering, soft excrement and the like. Tail-suspended rats have the similar symptoms as the SAS rats, like shutting eyes, less activities, syntexis, dispersed and dim clothing hair but no symptoms of soft excrement.(2)Changes of multiple index in simulated weightlessness rats1) Body weight and temperature: Compared with CON, after 14 days of tail-suspension, , body weight and temperature decreased obviously (P<0.001, P<0.01). There was no significant difference(P>0.05) between them and those in SAS.2) Organ index: Compared with CON, after tail-suspended 14 days, liver index, spleen index and thymus index decreased(P<0.01, P<0.01, P<0.05); there was no significant difference(P>0.05) between them and those in SAS.3) D-xylose excretion and activity of amylase in serum: after tail-suspension 14 days, compared with CON, D-xylose excretion and activity of amylase decrease(P<0.01, P<0.001); compared with SAS, there was no significant difference(P>0.05) between them and those in SAS.(3) Medicine disproof:1) Body weight and temperature: Compared with CON, the body weight and temperature of TS+W decreased(P<0.01, P>0.05); there was no significant difference(P>0.05) between the body weight of TS+M and those in CON.2) Organ index: Compared with CON, liver index, spleen index and thymus index decreased(P<0.01, P<0.001, P>0.05); liver index of TS+H and TS+M, spleen index of TS+M have no significant difference(P>0.05) with that in CON.3) BW and MWW/BW: Compared with CON, BW and MWW/BW of TS+W decreased significantly(P<0.01, P<0.01); BW, MWW/BW of TS+H and TS+M have no significant difference(P>0.05) with that in CON.4) SOL fiber proportion and CSA: Compared with CON, proportion type I fiber , CSA of type I and II fibers in TS+W decreased sharply(P<0.001); proportion of type I fiber and CSA of type II fiber in TS+M have no difference(P>0.05).Conclusions (1)Tail-suspended rat had a series of similar symptoms as SAS rat and SAS clinical patients(2)Comparing TS rat with SAS rat, there was no significant difference of organ.(3)There was no significant difference of the digestion-absorption index(D-xylose excretion and activity of amylase in serum) between the tail-suspended rat and the SAS rat, which has the same coherent trend to SAS clinical patients.(4)As to the medicine disproof, SJZD is a traditional medicine, which can be used to invigorate the spleen. Also it could improve the multiple physiological index" in Simulated Weightlessness rat.