Comparison Study Of The Expression And Distribution Of Ngb And HIF-1α In Different Brain Tissues Of The Yak And Cattle

The vertebrate central nervous system is highly sensitive to hypoxia.As a species with long-term adaptability to the hypoxic environment-yak(Bos grunniens),the central nervous system,especially the brain,must also have its special adaptation mechanism.Neuroglobin(Ngb)and Hypoxia-inducible factor-1α(HIF-1α)are two regulatory proteins that have been shown to be involved in the adaptation of the body to high altitude hypoxia,mainly in vertebrates high expression in the nervous system,and studies have found that HIF-1α can promote Ngb production in hypoxic-ischemic brain damage.At present,the expression and distribution characteristics of Ngb and HIF-1α in different brain tissues of yak under high cold and low oxygen environment are still unclear.Therefore,in order to further investigate the expression and interaction of Ngb and HIF-1α in different yak brain tissues during the adaptation to the cold and hypoxic environment,this study was used qRT-PCR,Western blot and immunohistochemistry(IHC)techniques to organize different regions of the yak brain.The expression and distribution characteristics of Ngb and HIF-1α were studied and compared with cattle.The specific research results are as follows:1)Ngb and HIF-1α mRNA and protein had different levels of positive expression in different tissues of yak and cattle telencephalon,and the expression trends were basically the same.Among them,Ngb and HIF-1α mRNA and protein of parietal lobe have the highest expression levels(P <0.05).In comparison,the expression of Ngb mRNA in different tissues of yak’s telencephalon was higher than that of cattle,the expression of HIF-1α mRNA was higher than that of cattle in the parietal lobe,and the other areas were basically the same as cattle.The expression level of Ngb protein in the telencephalon of yak was higher than that of cattle except for the piriform lobe.The expression level of HIF-1α protein in cattle was higher than that of yak except for cingulate gyrus.Immunohistochemical results showed that the distribution characteristics of Ngb and HIF-1α in different areas of the yak and cattle telencephalon were similar.They were mainly located in the cytoplasm of neurons or in a small portion of glial cells of telencephalon.Negative controls were notexpressed.2)Ngb and HIF-1α mRNA and protein had different levels of positive expression in different tissues between the yak and cattle diencephalon,and the expression trends were basically the same.Among them,the expression level of Ngb and HIF-1αmRNA were the highest in the pituitary and pineal of yak diencephalon(P <0.05).The expression level of Ngb and HIF-1α mRNA were highest in the pituitary of cattle diencephalon(P <0.05).In comparison,the expression levels of Ngb and HIF-1αmRNA in pituitary and pineal of yak were higher than that of cattle,and the expression levels in other areas were basically the same.The expression of Ngb protein in the yak diencephalon was highest in the pituitary and hypothalamus(P<0.05),and the expression of HIF-1α protein was the highest in the pituitary(P<0.05).The expression levels of Ngb and HIF-1α protein were highest in the pituitary of cattle diencephalon(P <0.05).In comparison,the expression levels of Ngb and HIF-1α protein in the yak diencephalon were higher than that of cattle.Immunohistochemical results showed that the distribution characteristics of Ngb and HIF-1α in different regions of yak and cattle diencephalon were similar,which were mainly located in the neurons cytoplasm.Negative controls were not expressed.3)Ngb and HIF-1α mRNA and protein had different levels of positive expression in different tissues of yak and cattle rhombencephalon,and the expression trends were basically the same.Among them,Ngb and HIF-1α mRNA and protein of yak rhombencephalon were the highest expressed in the archicerebellum(P <0.05).Ngb mRNA and protein of cattle rhombencephalon were highest in the archicerebellum(P<0.05),while the expression levels of HIF-1α mRNA and protein were highest in the archicerebellum and the cerebellar cortex(P <0.05).In comparison,the expression of Ngb mRNA in corpus medullane of the yak was lower than that of the cattle,and the expression level of the remaining regions was basically the same.The expression of HIF-1α mRNA in corpus medullane,neocerebellum,palaeocerebellum of the yak were lower than that of cattle,and the expression in other areas were basically the same.The expression of Ngb protein in the corpus medullane and palaeocerebellumof yak rhombencephalon was lower than that of the cattle,while the expression of Ngb protein in the other regions was higher than that of the cattle.The expression of HIF-1α protein in the yak rhombencephalon was higher than that of cattle.Immunohistochemical results showed that the distribution characteristics of Ngb and HIF-1α in different areas of yak and cattle rhombencephalon were similar,which were mainly located in the neurons cytoplasm.Negative controls were not expressed.4)The expression trends of Ngb and HIF-1α at the gene and protein levels in most areas of the yak’s telencephalon,diencephalon,and rhombencephalon were consistent and positively correlated,but in some areas,there are inconsistent expressions of genes and proteins.However,the expression trends of Ngb and HIF-1α at the gene and protein levels in the regional tissues of cattle’s telencephalon,diencephalon,and rhombencephalon were the same.The above-mentioned research results show that,in different brain tissues of yak and cattle,Ngb and HIF-1α genes and proteins are positively expressed in different degrees,indicating the conservative evolution of them.Among them,the expression levels of Ngb and HIF-1α genes and proteins in yak and cattle parietal lobe,pituitary and archicerebellum are highest,indicating that the three have high sensitivity and tolerance to hypoxia.The expression and distribution of Ngb and HIF-1α are basically the same in most areas of brain tissue of yak and cattle,suggesting that HIF-1α may have a direct or indirect synergistic effect on Ngb to improve the adaptation of yak and cattle brain to hypoxic environment ability.Compared with cattle,there are differences in the expression of Ngb and HIF-1α genes and proteins in certain areas of yak brain tissues.Analysis of the causes may be different from the functions performed by Ngb and HIF-1α in the corresponding areas of yak brain tissues.The preferential and selective expression in the process of long-term adaptation to the high cold and low oxygen environment is related,and its specific mechanism has yet to be verified by further experiments.