| Background and Objective: With the development of manned spaceflight, the effectsof especial gravity environment in space on the astronauts are getting more attention. Itwas reported that the body was damaged to a certainty degree in both high Gx load andweightlessness or simulated weightlessness. However, the few studies to research thecombined effect of both Gx load and weightlessness found whether the body got moreserious damage, and this kind of reports about oral tissue were much fewer. This studyinvestigated the effects of Gx load and simulated weightlessness on HSP70, c-fos andc-jun expression in the tongue striated muscle of rhesus macaque, and discussedwhether the tissue was injuried in this process, which may be provided the referencefor the astronauts’ oral health.Methods：(1)Twenty male rhesus macaque were randomly divided into four groups:control group(A，n=3),30d simulated weightlessness group(B，n=3),+13Gx group(C，n=3) and high+Gx exposure after30d simulated weightlessness group(D，n=11).(2)The HDBR(head down bed rest) was used as the method to establish the animalmode of simulated weightlessness.(3) The advanced58-type-animal centrifuge wasused to establish the animal mode of high Gx load.(4)The tissues were fixed with10%buffered formaldehyde and embedded with paraffin, and histopathological changeswere observed under microscope. The expression of Hsp70c-fos and c-jun weredetected by immunohistochemical method.(5) The positive cells percentage andintegrated optical density (IOD) value of positive cells were obtained to make the semiquantitative analysis to compare the expression of Hsp70, c-fos and c-jun in the every group.Results:(1) The normal structure of tongue striated muscle was observed in group A,and the “striated” structure was normal. There were no significant pathologicalchanges in the other groups, and occasionally, the intercellular substance scatteredthinly, few tongue striated muscle cells had irregular arrangement, and the striatedstructure was not unclear or disappeared.(2)Immunohistochemical stainingdemonstrated that over-expression of HSP70was detected in the nuclei and cytoplasmin group B, group C and group D, but there was no obvious staining in group A. Theexpression of c-fos showed negative staining in group A, but the c-jun showed weakpositive staining in group A, which was detected in the cellular cytoplasm. Theover-expression of c-fos and c-jun were detected in the structure of “striated” and somecellular nuclei.(3) The accumulated scores of HSP70showed that the changes weremore obvious in group D than that in group B and group C. But there was nosignificant difference in HSP70expression among the subgroups in group D. IODshowed that the c-fos expression were more significant difference in group B thangroup D3,which the c-jun were same with. In addition, the c-fos expression was moresignificant difference in group C than group D2, and group C than group D3.Conclusion:(1) The tongue striated muscle of rhesus macaque may have a certaindegree of tolerance in simulated weightlessness and high+Gx.(2) From the proteinlevel, simulated weightlessness and high+Gx both can induce an increase of HSP70,c-fos and c-jun expression in tongue striated muscle of rhesus macaque, implying theischemia and hypoxia may occur in the tissues during the acute response process,which may injury the muscle cell.(3)The immunohistochemical IOD showed thatstimulated weightlessness can aggravate the effects of high+Gx load on the tonguestriated muscle of rhesus macaque, implying they may be synergic relationship, whichcan enhance the damage of the muscle cells. |
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