Tissue Characteristics And Related Gene Expression Analysis Of Tibetan Pig Lung Adapted To High Altitude Hypoxia Environment

In order to explore how the lung tissues of Tibetan pigs respond to hypoxia under the stress of hypoxia ecological limiting factors,this study selected two 12-month-old Tibetan pigs living at different altitudes（3000m and 1000m）as the research objects.Du Changda ternary cross-bred pigs were used as a control,through which blood physiological and biochemical indicators were measured,and the blood vessels and lung tissues were studied using arterial vascular three-dimensional construction technology,scanning electron microscopy technology and tissue section technology（HE staining method）,and q RT-PCR method detected the relative expression levels of some hypoxia genes,and the results showed that:1.Through the comparison of the relative value（T/W）of the arterial diameter in each part of the body weight（T/W）,it is found that the T/W value of the Tibetan pig population is significantly（P<0.05）higher than that of the three-way hybrid pig population;Both were higher than those of the emigrated Jingchuan Tibetan pigs,and the difference was not significant（P>0.05）;scanning electron microscopy found that the left pulmonary arteriole specimens of Gannan and emigrated Jingchuan Tibetan pigs with a diameter ranging from 6.64 to 81.89μm had dents on the surface of the arterioles They are evenly distributed and large in number,mostly in the shape of"cucurbit"or"footprint".The length of the endothelial cell nuclear indentation is about 11.55～13.32μm,the width is about 5.22～6.51μm,and the surface of microvessels has shallow ring-shaped constrictions.2.There was no significant difference in the number of alveoli per unit area of lung tissue between Tibetan pigs and three-way hybrid pigs at different altitudes（P>0.05）.The alveolar diaphragm thickness of high-altitude populations was significantly higher than that of low-altitude populations,and the bronchiolar longitudinal folds of high-altitude populations The length of pigs at lower altitudes is longer and the difference is significant（P<0.05）;when the altitude is the same,the thickness of the alveolar diaphragm of Tibetan pigs is significantly greater than that of three-way hybrid pigs（P<0.05）,and the length of longitudinal folds of bronchioles in the lung tissue of Tibetan pigs is greater than three The difference is extremely significant（P<0.01）for Tibetan pigs,and the diameter of terminal bronchioles in Tibetan pigs is smaller than that of three-way crossbred pigs（P<0.01）.Tibetan pigs with circular smooth muscle thickness are significantly larger than that of three-way crossbred pigs（P<0.05）.3.The higher the altitude,the higher the red blood cell（RBC）.The hemoglobin concentration（HGB）and average red blood cell hemoglobin concentration（MCHC）of high-altitude pig breeds are significantly higher than those of low-altitude pig breeds（P<0.05）;The concentration of sodium ion（Na⁺）was significantly higher than that of low-altitude Tibetan pigs（P<0.05）,but there was no significant difference between three-way crossbred pigs;the potassium ion（K⁺）concentration of Jingchuan three-way crossbred pigs was significantly lower than that of other altitude pig breeds（P<0.05）;the partial pressure of carbon dioxide（Pco₂）of high-altitude Tibetan pigs was significantly lower than that of other groups（P<0.05）;the partial pressure of oxygen（Po₂）of high-altitude Tibetan pigs was significantly higher than that of other groups（P<0.05）,and three-way crossbred hybrid pigs were significantly higher than the low-altitude migration Jingchuan Tibetan pigs and three-way crossbred hybrid pigs（P<0.05）.4.The expression levels of HIF-1,VEGF,EPAS1 and EPO in the lungs of Gannan Tibetan pig and Yongdeng ternary cross-bred pigs were significantly higher than those in the Jingchuan area（P<0.05）;the low-altitude area migration Jingchuan Tibetan pigs and Sanyuan The expression of e NOS in hybrid pigs was significantly higher than that of Gannan Tibetan pigs and Yongdeng three-way crossbred pigs in high altitude areas（P<0.05）;the expression of EGLN1 in Tibetan pigs moved to Jingchuan was significantly higher than that of Gannan Tibetan pigs（P<0.05）,But there is no significant difference in the expression of EGLN1 between Yongdeng ternary hybrid pigs and Jingchuan ternary hybrid pigs.In summary,compared with low-altitude populations,Tibetan pigs have increased abundance of microvessels,increased alveolar septum thickness,increased blood oxygen transport capacity,and hypoxic adaptation-related gene expressions,all of which have undergone significant compensatory changes.These unique adaptation mechanisms increase the hypoxia tolerance of Tibetan pigs,so that Tibetan pigs can live in high-altitude areas for a long time.