Construction Of An ICU Acquired Weaknes Model In Rats With Sepsis

Objective:At present,there is still no animal model of ICU acquired weakness that is simple,reproducible and suitable for the pathogenesis and mechanism of the disease.This study intends to explore the feasibility of constructing a rat model of ICU acquired weakness by immobilizing the sepsis rats.Methods : Seventy-two healthy male SD rats were randomly divided into12 groups,6 in each group(control 3d,6d,9d group;immobilization 3d,6d,9d group;sepsis 3d,6d,9d group;sepsis and immobilization 3d,6d,9d group;).lipopolysaccharide endotoxin was injected into the abdominal cavity of the sepsis and sepsis and immobilization mice,while control and immobilization mice were intraperitoneally injected with the same dose of normal saline.Then immobilization and sepsis and immobilization rats were fixed to the rat fixator.Rats were sacrificed at the time of grouping.The weight of the rats before and after the experiment was recorded,and the bilateral gastrocnemius and diaphragm were collected.These specimens were stained with HE.Then The transverse diameter of the muscle fibers was measured using IPP 6.0 image analysis software.Furthermore,E3 ubiquitin ligase gene Atrogin-1 and Murf1 m RNA were detected by RT-PCR.Results:1.Changes in body weight of each experimental rat: By analyzing of pre-experimental body weight of each group,The results showe no significant difference(P>0.05).But,After the test is completed,the body weight changes of the rats in the immobilization group,the sepsis group and the sepsis and immobilization group were significantly higher than those in the control group(P<0.05);the changes of body weight in the sepsis and immobilization group was significantly higher than that of the immobilization group and the sepsis group(P<0.05).2.Morphological changes of gastrocnemius and diaphragm in each experimental rat: Under the microscope,the gastrocnemius and diaphragm muscle fibers of the rats in the immobilization group,the sepsis group and the sepsis and immobilization group were significantly atrophied compared with the control group;Simultaneously,compared with the sepsis group and the immobilization group,the gastrocnemius and diaphragm muscle fibers of the rats in sepsis and immobilization were significantly atrophied,and the fiber spacing was widened to varying degrees.3.The transverse diameters of the gastrocnemius and diaphragm muscle fibers of each experimental rat:The transverse diameter of the gastrocnemius and diaphragm muscle fibers were determined by IPP6.0 image analysis software,and the results showed that there was no significant difference in the control group at each time point(P >0.05);However,the transverse diameters of the gastrocnemius and diaphragm muscles in the immobilization group,the sepsis group and the sepsis and immobilization group were significantly lower than those of the control group at each time point(P<0.05);In addition,The transverse diameter of the gastrocnemius and diaphragm muscles in sepsis and immobilization was significantly lower than that in the sepsis group and the immobilization group.(P<0.05).4.The expressions of Atrogin-1 and Murf1 m RNA in gastrocnemius and diaphragm of rats in each experimental group: As compared with control group,immobilization group and sepsis group.the relative expressions of Atrogin-1 and Murf1 m RNA in gastrocnemius and diaphragm of rats in sepsis and immobilization group were significantly higher(P<0.05).Conclusion: 1.The gastrocnemius and diaphragm of rats in the sepsis and immobilization group showed significant atrophy compared with the other groups.2.Both sepsis and immobilization can cause skeletal muscle atrophy in rats,and at the same time,two treatments are given.The skeletal muscle atrophy effect is more obvious than the single factor.3.Immobilization plays an important role in limb muscle atrophy.While the state of sepsis has a certain effect on diaphragmatic atrophy.4.Immobilizing sepsis rats can be used to construct a simple ICU acquired weakness animal model.