The Investigation On The Influence And Mechanism Of The Movement And Absorptive Function Of Small Intestinal Of Rats After Simulated Weightlessness.

BackgroundNow,along with the development of spaceflight and emploment of international space station, aeronantics and aerospace have already been the emphasis project of the country. Furthemore they are efficiency reflection on the technology and military affairs among the countries. The improvement of the airship equipment and the secure of astronauts, physiology and pathological changes have become warm sports. Many researchs have indicated that simulated weightlessness caused the a series of changes such as Cardiovascular fuctional disorder, sclerotion loss, amyotrophy, immunefunction descend, endocrine functional disorder, space motion sickness and so on, which directly influenced to complete aviations and aerospaces duties .On the digestive system aspect, it has been reported that simulated weightlessness may result in appetite depression, the sensitivity of osmesthesia and gustatory sensation degrade. Especially digestive system symptom such as nausea, vomito, anorexia and so on when space motion sickness happened.Recently, some scholars presume that the changes of intestinal motility and absorptive function caused intestinal malabsorption for some electrolyte, amino acids, microelement. Thus directly or indirectly affect nerves, bone, muscle metabolism and nutrition. The individual report ,weightlessness may cause intestinal microecology disturbance.The researches for small intestine mucosa membrance were rarely reported in the world. In this article, rats were tail-suspended (-30 degrees) for 21d to simulate weightlessness. Make deeply reseachs in the small intestinal absorb and motor function such as: observations on the pathological changes of mucosal villi and ultrastructual changes of microvilli as well as a quantitative imaging analysis were carried out correspondingly; researches on the humoral factor (motilin and nitrogen monoxidum) which affect the small intestine digest and absorb functions; researches on the implelling motion of small intestinal and at the same time the quantitative analysis were carried out correspondingly.We intend to investigate the pathology and physiology aiteration of small intestine on the condition of simulated weightlessness; to investigate the influence degree of which some humoral factor act on small intestinal; to investigate the influential factor of small intestine motive power and so on. Inorder to provid important theoretical evidence for aerial diseases especially digestive system.AIM1 .To understand the rules of small intestinal motility and absorptive function on the condition of simulated weightlessness;2. To investigate the possible mechanism of small intestinal motility and absorptive function on the condition of simulated weightlessness.Methods90 Male Wistar hindlimb unweighting rats were randomly assigned to either a control group or simulated microgravity groups. For simulating microgravity animals were subjected to hindlimb unweighting HU for 14 days and 21 days. Observations on the pathological changes of mucosal villi and ultrastructural changes of microvilli as well as a quantitative imaging analysis were carried out correspondingly.The aim of the present work was to investigate the alterations in nitric oxide NO expression and motilin content of abdominal aorta from simulated microgravity rats. The way of radioimmunity was used to measure motilin. Stable metabolites of nitric oxide, were determined by the chemiluminescence method.ResultsOur results showed significant shortening and widening of villi and deepening of crypts (P＜0.01) . Quantitative imaging analysis showed a significant decrease in the density theheight and surface area of the microvilli (P<0.001 ) .Compared with controls, abdominal aorta from simulated microgravity rats showed a significant increase in motilin expression (P<0.05 ). The nitric oxide content of abdominal aorta showed no differences between the two groups.ConclusionResults prompt that the course of the damage of small intestine mucosa of simulated microgravity rats, and provid important theoretical evidence for aerial diseases especially digestive system.These data indicated that there were differential alterations in motilin expression and NO of abdominal aorta after hindlimb unweighting. We suggest that these changes might represent both localized adaptations to differential body fluid redistribution and other factors independent of hemodynamic shifts during simulated microgravity.