Expression And Distribution Of HIF-1α,Leptin And LEPR In Yak Epididymis At Different Ages

Yaks(Bos grunniens)live in the alpine steppe at an altitude of 3000 ～ 5000 m and have good adaptability to the plateau.Its skin,hair,meat,milk and other products are of high nutritional and economic value,so it has the reputation of "the boat of the plateau" and "all-round livestock".However,living in the extreme ecological conditions of Qinghai-Tibet Plateau for a long time,yak reproduction rate is low.The epididymis is an important reproductive organ of male animals.It is the part of sperm maturation,sperm nutrition,sperm storage and transport.At the same time,it plays the functions of absorption,secretion and aggregation of androgens,providing physiological microenvironment for sperm maturation.Hypoxia-inducible factor-1α(HIF-1α),Leptin and Leptin receptor(LEPR)play an important regulatory role in mammalian reproductive system.However,their role in the development of yak epididymis has not been reported.In this study,the temporal and spatial expression characteristics of the above factors are studied in yak epididymal tissues of different ages(juvenile,adult and elderly)and different parts(Caput,Corpus and Cauda).The results are as follows:(1)In this study,the expression distribution of HIF-1α,Leptin and LEPR in the head,body and tail of the epididymis of yaks at different ages is studied.Immunohistochemical results shows that there is no significant difference in the expression distribution of HIF-1α in the epididymis of yaks at different ages.HIF-1αprotein is expressed in epididymal epithelial cells,basal cells,smooth muscle cells and sperm in the head,body and tail of the epididymis.HIF-1α protein is strongly expressed in the head of the epididymis of yak,and HIF-1α protein is mainly expressed in the epididymal epithelium.Leptin and LEPR are mainly expressed in epididymal epithelium,basal cells and smooth muscle cells,with strong positive expression in epididymal epithelium.(2)q PCR results shows that HIF-1α gene expression in adult yaks is higher than that in old yaks and younger yaks.The expression of HIF-1α in the caupt of the epididymis is significantly higher than that in the caput of the epididymis and the cauda of the epididymis at all ages(P < 0.05),in order of the caput of the epididymis > the corpus of the epididymis > the cauda of the epididymis.The gene expression levels of Leptin and LEPR in young yak are significantly higher than those in adult and old yak(P < 0.05),and the expression levels of Leptin and LEPR in caudal epididymis are significantly higher than those in caput epididymis and in cauda epididymis(P < 0.05),in order of the cauda of the epididymis > the caput of the epididymis > the corpus of the epididymis.(3)Western blot results shows that HIF-1α,Leptin and LEPR proteins are expressed in the epididymis of yaks at different ages.The expression level of HIF-1αprotein is the highest in the adult group,and the expression level is adult > old >young,with a decreasing trend.The expression of HIF-1α protein in the epididymis of yaks at different ages is the caput of the epididymis > the corpus of the epididymis >the cauda of the epididymis,and there are significant differences among different parts(P < 0.05).Leptin and LEPR protein expression levels are the highest in the young group,and the expression levels are in the order of young > adult > old,with a decreasing trend,and the differences among different ages are significant(P < 0.05).Leptin and LEPR proteins are found to have the highest expression levels in the tail of juvenile epididymis.There is no significant difference between the head of the epididymis and the epididymis(P > 0.05),but there are significant differences between the tail of the epididymis and the two parts of the epididymis(P < 0.05).Leptin and LEPR protein expression levels in adult and elderly epididymis are in the order of the cauda of the epididymis > the caput of the epididymis > the corpus of the epididymis,and there are significant differences among different parts(P < 0.05).In conclusion,the expression of HIF-1α is the highest in the epididymis of adult yaks,and the expression of HIF-1α is different in different parts of the epididymis,and the expression of HIF-1α is the highest in the epididymis head,indicating that HIF-1α maintains high concentration in the epididymis head environment and plays an important role in regulating the development of the epididymis and nutritive sperm.Leptin and LEPR expression levels in the epididymis changed significantly before and after sexual maturity,and Leptin concentration is higher in the tail environment of the epididymis.The differences of HIF-1α,Leptin and LEPR in the epididymis of yak suggest that they are important for the maturation,storage and energy conservation of yak sperm.This study provides reference for further research on reproductive regulation mechanism of male yak in plateau environment.