Abstract: This study was conducted to investigate the distribution and expression of platelet-derived growth factor receptor-β (PDGFR-β)in yak lungs, and to explore the adaptation mechanism of yak lungs to high altitude hypoxia environment. Immunohistochemistry, Western-blot technology and qRT-PCR were used to study the exact distribution and expression of PDGFR-β in the lungs of newborn, 1-year-old, 3-year-old, and 6-year-old yak. The results showed that PDGFR-β was mainly distributed in the bronchial and epithelial cells of the lung, pulmonary vascular endothelial cells, and smooth muscle cells of the bronchial wall, and its expression was strong. A small amount PDGFR-β was distributed in the smooth muscle cells of the bronchial wall and alveolar septal cells, and its expression was weak.PDGFR-β mRNA and protein were expressed at different levels in the lungs of yak at different ages. In terms of protein level, the newborn group was extremely significantly higher than those of the other 3 groups (P<0.01); in the 1, 3, and 6 years old groups, PDGFR-β expressions were not significantly different when compared with each other (P>0.05). In the mRNA expression level, the expression in the newborn group was the strongest and extremely significantly higher than those of the other 3 groups (P<0.01); PDGFR-β expression in the 1-year-old group was extremely significantly higher than the 3-year-old group and 6-year-old group (P<0.01); the expression difference was significant between the 3-year-old group and the 6-year-old group (P<0.05). The results indicated that PDGFR-β played an important role in the development of airways and pulmonary arteries and in the formation of adaptive structures in yaks at different ages, and this was most obvious in the newborn to 1 year old period.

Key words: yak, lung, platelet-derived growth factor receptor-beta (PDGFR-β)