| Eospalax cansus is a typical subterranean rodent which belong to the Spalacidae,Myospalacinae,Eospalax.As an subterranean rodent,E.cansus adapted to the underground environment with hypoxia and high carbon dioxide,whose caves are closed.In order to cope with the hypoxia and high energy consumption environment,the subterranean rodent has formed a unique morphological structure and physiological mechanism.E.cansus are an ideal pattern animal for studying the evolution of hypoxia and widely distributed in China.The muscles related to the toot of Eecansus are powerful,and are suitable for underground tunnel excavation activities.Glucose metabolism and lipid metabolism are energy sources for muscle activity.In the glucose metabolism,the glucose-driven glycolysis,which is limited by phosphofructokinase(PFK).The glycolysis in organisms is mostly glucose-driven glycolysis.Fructose-driven glycolysis metabolic pathway does not require the main rate-limiting step of PFK.Therefore,fructose enters glycolysis faster than glucose,which can quickly and efficiently supply energy to the organisms.It has been confirmed in our laboratory that the E.cansus can use fructose-driven glycolysis to provide energy for the body under the 6-hour experiment of 6.5%O2 concentration.Compared with mice,The subterranean rodent Hererocephalus glaber,have higher high-density lipoprotein(HDL),low-density lipoprotein(LDL).and total cholesterol(TC).Hypoxia can promote the oxidation of fatty acids in humans and animals,providing more energy to the body.Long-term hypoxic exercise promotes the oxidation of fatty acids in humans and animals,and the oxidative decomposition of lipids provides more energy to the organisms.It can be speculated that E.cansiis' blood lipid level and energy metabolism are different from the ground mouse in the long-term hypoxia evolution adaptation.In this study,we used biochemical and molecular biology,bioinformatics and histology to explore the expression of lipid and carbohydrate metabolism related genes in skeletal muscle of E.cansus under different oxygen concentrations.We set four exprement groups:21%O2 concentration,6.5%O2 concentration lasts for 6 hours,10.5%O2 concentration lasts for 44 hours and 10.5%O2 concentration lasts for 10 days.SD rats were used as controls experiment.Based on the Transcriptole sequencing of skeletal muscle.This study determined hypoxia-inducible factor HIF-1?,key genes ACAA2,ACC2 of lipid oxidation,key genes ACC1,SCD1 of fatty acid synthesis pathways,key genes ALDOA,GLUT1 of Glucose-driven glycolysis and key genes ALDOC,GLUT5 of fructose-driven glycolysis in skeletal muscle.The above gene mRNA was quantified by qPCR.The fat in skeletal muscle was localized by oil red O staining.The contents of glucose(GLU),total cholesterol(TC),triglyceride(TG),low density lipoprotein(LDL)and high density lipoprotein(HDL)in serum of E.cansus and SD rats were measured.The main results are as follows:1.In the skeletal muscle of E.cansus and SD rats,the expression of HIF-1? at 6.5%O2 for 6 hours was significantly higher than that at 21%O2.It indicated that the hypoxic stimulation signal was felt in both E.cansus and SD rats at 6.5%O2 concentration,and the signal was weakened after long-term treatment(10.5%O2 concentration forlo days).2.At 21%O2 concentration,the serum levels of TC,HDL and LDL in E.cansus were higher than those in SD rats,while TG was lower than SD rats.E.cansus has higher HDL in serum.3.Under long-term hypoxic exposure(10.5%O2 concentration for10 days),the expression levels of ACAA2 in E.cansus were higher than SD rats.The expression levels of E.cansus' ACC2 were higher than 6.5%O2 concentration.There was no significant difference in the expression of ACC2 in SD rats between different treatments.It can be speculated that the lipid oxidizing ability of E.cansus is stronger than that of SD rats under the long-term hypoxic environment environment.4.Under long-term hypoxic exposure(10.5%O2 concentration for10 days),the expression levels ofACC1 and SCD1 in E.cansus were significantly higher than those in SD rats.It is speculated that the fatty acid synthesis level of E.cansus is also significantly higher than that of SD rats under prolonged hypoxia exposure.According to the oil red 0 slice,there was no lipid accumulation in the skeletal muscle of E.cansus and SD rats.5.After three kinds of-hypoxic exposure,the GLU content in the serum of E.cansus and SD rats increased compared with the 21%02 concentration,and the GLU content of SD rats was always higher than that of E.cansus.In the short-term hypoxic exposure group(6.5%O2 for 6 hours and 10.5%O2 for 44 hours),the expression of GLUT1 mRNA in E.cansus and SD rats was significantly up-regulated;there was no significant difference in ALDOA content in E.cansus,while SD rats were significantly higher than the 21%02 concentration expression.It can be speculated that under short-term hypoxic exposure,the glucanolytic levels of E.cansus and SD rats are up-regulated,and the level of glucose glycolysis in E.cansus may be lower than that in SD rats.6.Short-term acute hypoxic exposure(6.5%O2 concentration for 6 hours),the mRNA expression levels of GLUT5 and ALDOC in E.cansus and SD rats were significantly higher than those in 21%O2 concentration.It is presumated that 6.5%O2 concentration under acute hypoxic exposure,the glucose metabolism was up-regulated in both E.cansus and SD rats.Long-term hypoxic exposure(10.5%O2 concentration for 10 days),GLUT5 and ALDOC expression in E.cansus was not significantly higher than 21%O2 concentration,but they were significantly higher than 21%O2 concentration in SD rats.It can be speculated that the sugary glycolysis of E.cansus is only high in the 6.5%02 acute hypoxic group.The fructose of skeletal muscle in SD rats is in the 6.5%O2 acute hypoxia and long-term hypoxic exposure group(10.5%O2 concentration for 10 days)are at a higher level.The results of this study indicate that acute hypoxic treatment(6.5%O2 concentration for 6 hours)causes hypoxia-inducible signaling in skeletal muscle of E.cansus and SD rats,and HIF-1? regulates glycolysis by up-regulating downstream target genes.The fructose-driven glycolysis of SD rats not only improved significantly under the treatment of 6.5%O2 concentration for 6 hours,but also had a high level of metabolism during the long-term(10 days)hypoxia treatment at 10.5%O2 concentration.Under long-term hypoxic treatment,E.cansus may use the energy released by lipid oxidative decomposition more effectively.At the same time,the level of fatty acids synthesis in E.cansus may also be higher than that of SD rats.In summary,E.cansus has high levels of glucose glycolysis and fructose glycolysis in the acute hypoxic treatment group(6.5%O2 concentration for 6 hours),and the level of lipid metabolism during prolonged hypoxic exposure(for 10 days)was higher than that of SD rats.The energy utilization patterns and metabolic levels that may be caused by the gene expression levels of E.cansus different from ground mice may be related to the long-term low-oxygen and high-energy evolutionary adaptation. |
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