Histological Observation Of Blood Vessels And Nerves And Expression Of HIF-1α 、VEGF In Adult Yaks Skin

The purpose of this study was to investigate the distribution of vessels and nerves in different parts of yaks skin,to detect the location relative expression of HIF-1α and VEGF in different parts of yaks skin,and to explore the adaptation mechanism of yaks skin to the plateau hypoxia environment.The vessels and nerves in the skin of adult yaks were observed and analyzed by H.E,Masson′s staining and Verhoeff VG staining.The HIF-1α and VEGF genes and proteins in different parts of adult yak skin were mapped and quantitatively detected by immunohistochemistry,quantitative real-time PCR(q RT-PCR)and western blot(WB),and the differences of their expression levels were analyzed.The results showed that the density of vessels and nerves was highest in the neck,followed by the forearm and crus,and lowest in the metatarsus,there were significant differences among the parts(P<0.05).The number of vessels and nerves from the neck to the metatarsal showed a decreasing trend,with significant difference between different sites(P<0.05).HIF-1α was mainly expressed in epidermis,the epithelial root sheath of hair follicles,sebaceous glands,sweat gland,vessels and nerves;Strong positive expression was found in the neck,forearm and crus,and positive expression in the metatarsus(P<0.05).The main expression sites of VEGF were basically the same as HIF-1α,the neck,forearm and calf were strongly expressed in the medial membrane of blood vessels,and the plantar was strongly expressed in the inner elastic membrane of blood vessels.The relative expression level of HIF-1α m RNA in the metatarsus was significantly lower than that in the other three sites(P<0.05),but there was no significant difference in the other three sites(P>0.05).The relative expression of HIF-1α protein was the highest in the neck and the lowest in the metatarsus.The difference was significant(P< 0.05).The relative expression of VEGF protein was consistent with that of HIF-1α.The density of blood vessels and nerves in the skin of adult yaks decreased from the trunk to the limbs and forelimbs to the hind limbs.It is speculated that the neck skin is more suitable to the hypoxia environment.The expression trend of HIF-1α and VEGF was basically consistent with the trend of blood vessel and nerve density,suggesting that blood vessels and nerves in the skin play a role in the adaptive mechanism of hypoxia.