| Aquaporin(AQP)is a transmembrane protein mainly effects on regulating water molecule transport,and maintains the water-liquid balance of the body.It is expressed in many tissues and organs,and plays an important physiological functions.In order to adapt the hypoxic environment on the plateau,the tibetan sheep showed different structural characteristics of their heart and lungs from those of plain animals.Whether the amniotic fluid metabolism is unique in the plateau and whether AQPs family proteins expressed in different organs of the tibetan sheep has no reportes.In order to study the expression characteristics of AQPs in different organs of the tibetan sheep,reveal the relevant characteristics of the tibetan amniotic fluid metabolism,and to provide theoretical basis for the adaptability of the tibetan sheep to the hypoxia.Samples was collected from the tibetan sheep's cerebral and cerebellar cortex,heart,liver,spleen,lung and kidney,histological staining techniques were used to study the structural characteristics of those tissues.Immunohistochemical staining,real-time quantitative PCR was used to analysis the expression of AQPs.The results showed as follows:1.The epicardium and endocardium thickness of the the tibetan sheep was343.53±18.91?m and 259.93±17.4?m respectively;the alveolar septum thickness of the lung was 2.53±0.16?m,and the number of alveoli per(mm~2)area is 21.13±2.05,which were significant higher than that of small-tailed han sheep in low altitude.(P<0.05).2.Immunohistochemical staining results showed that:in the cerebral and cerebellar cortex,AQP1,AQP4 and AQP9 were expressed in the cytoplasm and nerve fibers,AQP9 were also detected in the nucleus,and the expression intensity of AQP4was(48.06±1.18,35.08±1.02)significantly lower than AQP1(67.45±0.78,68.69±0.65)and AQP9(69.79±1.25,70.16±0.87)(P<0.05).In the heart,AQP1 and AQP9 were mainly detected in the cytoplasm of cardiac endothelial cells,Purkinje fibers,cardiomyocytes,and vascular smooth muscle cells,while AQP4 was mainly located in Purkinje fibers and cardiomyocytes,and strong positive staining showed in Purkinje fibers.The expression intensity of AQP9(18.57±0.74)was significantly lower than that of AQP1(21.42±1.20)and AQP4(35.61±0.84)(P<0.05).In the liver,AQP1 is mainly located in the cytoplasm of hepatocytes,the strong expression were showed in vascular endothelium of interlobular veins and interlobular arteries,and weaker expression in vascular smooth muscle.AQP4 was mainly located in the membrane of hepatocytes,and there showes no positive staining in vascular endothelium and vascular smooth muscles,AQP9 was strongly expressed in the cytoplasm of hepatocytes,also expressed in the nucleus,and strongly expressed in vascular smooth muscle.The expression intensity of AQP9(60.28±1.67)was significantly higher than that of AQP1(40.85±0.78)and AQP4(28.68±0.87)(P<0.05).In the spleen,AQP1 was mainly located in the red pulp,expressed in the capsule and splenic trabecular smooth muscle cell,strongly expressed in the central artery vascular endothelium.AQP4 was expressed in the red pulp,AQP9 was mainly distributed in the red pulp and white pulp,mainly detected in the central artery endothelium,and the expression intensity of AQP4(1.35±0.41)was significantly lower than that of AQP1(10.45±0.96)and AQP9(10.51±1.01)(P<0.05).In the lungs,AQP1,AQP4,and AQP9 was expressed in alveolar epithelial cells.AQP4 is abundantly expressed in the serous membrane of the lung and vascular smooth muscle cells.AQP9 was expressed in the bronchiolar epithelial cells and located in the nucleus.The expression intensity of AQP9(12.36±0.41)was significantly lower than AQP1(52.86±1.28)and AQP4(44.13±0.61)(P<0.05).In the kidney,AQP1,AQP4,and AQP9 expressed in the cytoplasm of renal tubular and collecting duct epithelial cells and vascular endothelium.AQP9 was mainly located in the renal tubular base at the base of epithelial cells,and the expression intensity of AQP9(27.50±0.89)was significantly lower than that of AQP1(31.53±1.09)and AQP4(34.3±1.46)(P<0.05).3.The results of real-time fluorescence quantitative PCR showed that AQP1,AQP4,and AQP9 were expressed in various tissues of the tibetan sheep,and the expression levels varied greatly.AQP1 expression in the cerebellar cortex(8.51±0.54)was significantly higher than that of the heart(3.22±0.73),liver(4.15±0.18),kidney(3.87±0.43)and spleen(1.95±0.48)(P<0.05);AQP4 expression in the cerebral cortex(5.8±0.53)was significantly higher than that in the cerebellar cortex(3.96±0.39),heart(3.95±0.52),liver(3.00±0.49),spleen(0.38±0.34),lung(4.55±0.56)and kidney(3.64±0.37)(P<0.05);AQP9 expression in liver(7.16±0.44)was significantly higher than that of heart(2.64±0.28),lung(2.16±0.36),kidney(2.83±0.08)and spleen(1.96±0.06)(P<0.05).In summary,AQP were expressed in those tissues of the tibetan sheep.The expression level and distribution characteristics showed tissue-specific.These results provide an experimental basis for further comprehensive interpretation of the characteristics and mechanisms of water metabolism in pletue animals lived in low temperatures,low oxygen,and low pressure. |
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