Font Size: a A A

Studies On The Response Mechanism Of Antioxidant Defense System Of Lasiopodomys Brandtii To Hypoxia Stress

Posted on:2022-08-27Degree:MasterType:Thesis
Country:ChinaCandidate:X R WangFull Text:PDF
GTID:2480306326498304Subject:Zoology
Abstract/Summary:PDF Full Text Request
The antioxidant defense system of organisms is mainly composed of antioxidant enzyme system and low molecular weight antioxidant system.The antioxidant enzyme system mainly includes a series of antioxidant enzymes such as superoxide dismutase(SOD),catalase(CAT)and glutathione peroxidase(GPx),which can catalyze the degradation of reactive oxygen free radical(ROS),while the low molecular weight antioxidants system mainly includes small molecules with antioxidant activity,such as glutathione(GSH)and vitamin C(VC).Under normal circumstances,the formation of ROS in the tissue is in a low level of equilibrium.When the balance is broken by various factors,excessive ROS will cause oxidative stress to the body,and the antioxidant defense system can eliminate the oxidative damage caused by ROS.Lasiopodomys brandtii(L.brandtii)is a typical gregarious small rodent with a cave system as a unit.In winter clusters,increasing population density in the cave system,soil compaction in the tunnel,and snow covering the entrance of the tunnel will cause the oxygen content in the tunnel to decrease,forming a temporary hypoxic environment.Previous studies have found that Brandt's voles are more resistant to hypoxia than Kunming mice.Compare with the typical underground rodent,Brown voles,Brandt's voles are less able to respond to hypoxic stress at the transcriptional regulation level.It is speculated that the antioxidant defense system played an important role in the process of Brandt's vole responding to hypoxia stress.In this paper,we used the oxygen chamber to simulate different hypoxic environments that Brandt's voles might suffer in the field(mild hypoxic:10.0%O2,6h;severe hypoxia:5.0%O2,6h;normoxia:20.9%O2,6h),the activity of related antioxidant enzymes,the content of small molecular antioxidants and the level of oxidative damage in the brain,liver and kidney were measured,and the antioxidase-related genes were quantized.Based on the theoretical framework of antioxidant enzyme system and low molecular weight antioxidant system,this study revolves around the changes of oxygen content that Brandt's vole may suffer in winter,combined with physiological means,biochemistry and molecular biology techniques.In-depth analysis of the stress response model of antioxidant defense system in Brandt's vole at physiological,biochemical and molecular level under different hypoxia environment.The main results are as follows:1.Response of MDA and PCO in brain,liver and kidney to hypoxia stressThe cluster environment of 11 Brandt's voles were simulated in the laboratory,and the average O2 concentration was 15.31%(12.84%-17.30%)within 8 hours.There was no significant change in the levels of MDA and PCO in brain,liver and kidney of Brandt's vole under 10%hypoxia treatment,while the level of MDA in brain and liver decreased significantly and the level of MDA in kidney increased significantly in 5%hypoxia treatment.There was no significant difference in kidney PCO level between the two hypoxia treatments.This suggests that the experience of hypoxia in the wild allows Brandt's voles to tolerate 10%of mild hypoxia,while 5%of severe hypoxia stress may lead to intolerance such as lipid peroxidation damage in the kidney tissue of Brandt's voles.2.Response of antioxidant enzyme system in brain,liver and kidney to hypoxia stressThe expression of Cu/Zn SOD gene in Brandt's vole brain was significantly up-regulated and down-regulated by 10%and 5%hypoxia treatment.There was no significant change in brain antioxidant enzyme activity in 10%hypoxia treatment,and only SOD activity increased significantly in 5%hypoxia treatment.The expression of Nrf2 and its downstream antioxidant enzyme genes Cu/Zn SOD,GPx1 and GPx3 were significantly up-regulated and GPx activity was significantly decreased in 10%hypoxia treatment,while Mn SOD gene expression was significantly down-regulated in 5%hypoxia treatment,while other gene expression and antioxidant enzymes activity had no significant change.There was no significant difference antioxidant enzyme gene expression of 10%and 5%hypoxia treatment in kidney.10%hypoxia treatment significantly decreased GPx activity,while 5%hypoxia treatment significantly increased SOD activity in kidney.This shows that in the hypoxic environment,the antioxidant enzyme system mainly plays an important antioxidant function in the liver.In addition,although there is little fluctuation in the transcriptional level and enzyme activity level of antioxidant enzymes in brain and kidney,the absolute content of antioxidant enzymes in brain and kidney is significantly higher than that in model animals such as mice and rats,and some of them are even close to blind mole rats.Brandt's vole is likely to cope with the fluctuation of oxygen content in the wild environment by maintaining"high and stable antioxidant capacity".3.Response of low molecular weight antioxidants system in brain,liver and kidney to hypoxia stressAfter 10%and 5%hypoxia treatment,there was no significant difference in the level of GSH in the three organs of Brandt's vole,only the activity of GR in kidney decreased significantly,and the content of VC in brain increased significantly.This suggests that VC mainly plays an antioxidant and defensive role in the brain of Brandt's vole under hypoxic environment.The conclusion:Brandt's vole is a small rodent that experiences intermittent hypoxia in the natural environment,and its antioxidant defense system plays an important role in dealing with environmental hypoxia.However,different from typical subterranean rodents such as blind mole rats and naked mole rats,Brandt's voles rely more on high and stable polyconstituent antioxidant activities and low molecular weight antioxidants such as VC to reduce or eliminate oxidative damage caused by hypoxia.At the same time,although Brandt's vole can tolerate hypoxia to some extent,the significant decrease in the activities of antioxidant enzymes such as GPx and GR in multiple tissues and the increase of lipid peroxidation in kidney tissue indicate that long-term hypoxia will also pose a threat to the survival of the species.
Keywords/Search Tags:Brandt's vole, Hypoxia, Antioxidant defense system, Antioxidant enzyme, Low molecular weight antioxidant
PDF Full Text Request
Related items