Research In The Function Of HIF1 And RPS3 In Hypoxic Acclimatization In Rats Tissues

Plain people who are not acclimatized and ascended rapidly to high altitudes will be easily affected by the hypoxia and suffered acute mountain sickness.The functions of the system of oxidative stress can be affected significantly by hypoxia;oxidative stress will damage the high oxygen consumption organizations such as brain and skeletal muscle.In human tissues,the brain is the most sensitive organ to the change of oxygen,the brain injury which caused the symptoms such as sleep disorder,headache and so on occurred at the earliest under high-altitude hypoxia.Skeletal muscle is the major organ of the body movement,hypoxia would reduce the energy storage of muscle,plain people appear obvious symptoms such as fatigue,lack of power after entering high altitudes,the injury of skeletal muscle will influence the performance and reduce the fighting capacity of plateau troops.Therefore hypoxia has a big effect on the body’s physiology and health,and even causes injury.HIF1 is a central regulator of hypoxia control and Rps3p has the function of the resistance to oxidative stress,this topic studied on physiology,pathology and molecular biology in rats after different hypoxia stimulation,explored the role of HIF1 signal transduction genes and RPS3 gene in rats brain and skeletal muscle in hypoxic acclimatization from the level of gene regulation.Healthy adult Wistar rats were randomly divided into group A:control group,group B:intermittent hypoxia group（IH）,group C:acute 5500m hypoxia group（AH group）and group D:intermittent hypoxia before acute 5500m hypoxia group（IH-AH group）.Intermittent hypoxia and acute hypoxia were simulated by hypoxia chamber.The studies of this topic are as follows:（1）to study the effects on physiology and pathology of rats under different hypoxia stress,blood gas and biochemical indicators in rats were compared;extracted the rats brain and skeletal muscle,made pathological slices and observed the changes;（2）to explore the role of HIF1 signal pathway genes and RPS3 gene during the process of hypoxic acclimatization in rats brain,Real-time PCR technology was used to test HIF1 related genes and RPS3 gene mRNA expression differences;（3）to explore the protection mechanism of HIF1 signal pathway genes and RPS3 gene in rats skeletal muscle in hypoxic acclimatization.Using Real-time PCR to analyze HIF1 related genes and RPS3gene expression differences in rats skeletal muscle.Rat L6 skeletal muscle cells were cultured under hypoxia environment for 24 hours,then Real-time PCR and Western Blot technology were used to detect the expression differences between RPS3 gene and Rps3p protein.The first part of this study proved that the rats ALP,ALT,AST,uric acid were not significantly changed after different hypoxia stimulation,creatinine values changed within the physiological range,inferred that rats’liver and kidney didn’t be damaged.Brain edema and nucleus pycnosis were caused by intermittent hypoxia,acute 5500m hypoxia and intermittent hypoxia before acute 5500m hypoxia in all rats,and the injury degree aggravated orderly,so intermittent hypoxia preconditioning did not promote hypoxic acclimatization of rats brain.Skeletal muscle didn’t appear obvious pathological changes.Blood physiological index results showed that pO₂ and SO₂%of rats were decreased significantly after ascending rapidly to 5500m hypoxia environment,mild hypoxemia was appeared in rats without intermittent hypoxia preconditioning,compared with the acute 5500m hypoxia rats,pO₂ and SO₂%values were higher in the rats with intermittent hypoxia preconditioning before ascend rapidly to 5500m hypoxia;pCO₂,HCO₃-,BB,BE were significantly reduced after acute hypoxia exposure,rats appeared respiratory alkalosis combined metabolic acidosis,but the changes of the acid-base balance indexes in rats with intermittent hypoxia preconditioning varied less than acute hypoxia rats;after different hypoxia stimulation,blood red cells,hemoglobin and hematocrit values were significantly increased compared with the control group and showed the body improved oxygen supply by increasing the hemoglobin concentration after hypoxia stimulation,rats red blood cells,hemoglobin and hematocrit values were more closer to normoxic levels in the rats of intermittent hypoxia before acute 5500m hypoxia group,showed that intermittent hypoxia preconditioning could improve the body’s oxygen intake,reduce erythrocytosis,promote hypoxic acclimatization.The second part of the experiment showed that from the gene expression level in rats brain,intermittent hypoxia increased VEGFA,VEGFB,NOS3 gene expression;HSPA1B,NOS1 and VEGFB obviously decreased after acute hypoxia;the expression of HSPA1B,NOS3,VEGFB gene were reduced and EPO and HSPA1A were raised in rats with intermittent hypoxia preconditioning before ascending rapidly to 5500m hypoxia.Different hypoxia stimulation promoted HIF1 signal pathway upstream EGLN1 and VHL genes expression and reduced HIF1A gene expression;however RPS3 gene did not change significantly.The third part of the experiment showed that in rats skeletal muscle,EPO,HSPA1A and HSPA1B gene were significantly raised in great quantities by acute hypoxia stimulation,intermittent hypoxia and acute hypoxia induced rats skeletal muscle NOS1,NOS2 and NOS3 gene expression.Experiment results also showed that in rats skeletal muscle of the intermittent hypoxia preconditioning before acute hypoxia and L6 skeletal muscle cells treated with low oxygen,RPS3gene expression was increased significantly,we could extrapolate that rats skeletal muscle under hypoxia stress could against oxidative stress damage and promote hypoxic acclimatization of skeletal muscle,reduce the damage caused by hypoxia stress by raising HIF1 target genes and RPS3 gene.This study examined the influence on physiology and pathology of rats under different hypoxia stress,and explored the role of HIF1 signal transduction genes and RPS3 gene in rats’brain and skeletal muscle in hypoxic acclimatization;we can draw the following conclusion:1.The different hypoxia stimulation had different impact on rats physiological,intermittent hypoxia preconditioning could promote rats hypoxic acclimatization,physiological changes in the rats was smaller,intermittent hypoxia preconditioning before acute hypoxia improved the pO₂ and SO₂%values,and made the physiological index levels closer to normoxic.Intermittent hypoxia preconditioning promoted hypoxic acclimatization of rats’skeletal muscle to,but caused injury to the brain;2.Intermittent hypoxia preconditioning did not promote rats brain hypoxic acclimatization,and different hypoxia stimulation caused rats brain injury,it was related with the changes of VEGF,NOS,EGLN1,VHL,HIF1A gene expression by different hypoxia stimulation;3.Intermittent hypoxia preconditioning promoted rats skeletal muscle hypoxic acclimatization and protected the rats skeletal muscle from hypoxia injury.Different hypoxia stimulation induced HIF1 target genes such as NOS1,NOS2,NOS3 gene expression,EPO,HSPA1A,HSPA1B gene were increased by acute hypoxia,RPS3 gene was increased in rat skeletal muscle by intermittent hypoxia preconditioning before acute hypoxia and L6 cells after hypoxia,it was one of the mechanisms of intermittent hypoxia preconditioning promoted hypoxic acclimatization of rats skeletal muscle.