血管内皮生长因子B在牦牛间脑和脑干相关组织的表达与定位

Expression and localization of vascular endothelial growth factor-B in diencephalon and brainstem related tissues of the Yak’s brain

目的了解牦牛间脑和脑干不同区域血管内皮生长因子B(VEGF-B)的表达及分布特征,探讨其与低氧适应性之间的关系。方法选取5头健康牦牛,按照脑大体解剖结构进行分区并采集间脑和脑干相关组织,具体包括垂体、丘脑、下丘脑、延髓和脑桥5个部位。利用Real-time PCR、Western blotting及免疫组织化学技术对VEGF-B在牦牛间脑和脑干相关区域的表达与定位进行研究。结果牦牛间脑和脑干相关组织中VEGF-B mRNA表达水平最高的部位为垂体,显著高于其他部位(P<0.05),其余表达水平依次为下丘脑、丘脑和延髓,脑桥表达量最低;牦牛间脑和脑干相关组织VEGF-B蛋白表达水平除丘脑高于下丘脑外,其余部位表达水平与mRNA表达趋势一致。免疫组织化学结果显示,与阴性对照组相比,VEGF-B蛋白阳性物质主要分布于上述各类细胞的胞质。其中,垂体中VEGF-B阳性着色主要表达于嗜酸性细胞中;丘脑和下丘脑中VEGF-B阳性着色主要集中于多形细胞;延髓和脑桥中VEGF-B阳性反应主要集中在神经元胞体中。结论VEGF-B蛋白在牦牛间脑和脑干中均有表达,可能与其所担负的抗细胞凋亡、“生存因子”以及血管再生等功能密切相关;间脑和脑干不同区域的表达差异可能与各区域的组织特异性及其功能差异有关。

Objective To explore the expression and distribution characteristics of vascular endothelial growth factor-B(VEGF-B)in diencephalon and brainstem of Yak’s brain tissues,and to investigate the associations between its expression and hypoxia adaptation.Methods Five healthy yaks were selected,and the brain tissues were divided and collected according to the gross anatomical structure of the brain,including pituitary,thalamus,hypothalamus,oblongata and pons.The characteristics of expression and location of VEGF-B in different regions of Yak’s brain tissues were detected by Real-time PCR,Western blotting and immunohistochemical techniques.Results The results showed that the highest expression level of VEGF-B mRNA of yak brain tissue was in the pituitary,and the content was significantly higher than that found in other parts of the brain(P<0.05).Following the expressions were in the hypothalamus,thalamus and medulla oblongata,while the lowest expression level was in pons.The expression level of VEGF-B protein in Yak’s brain tissue was similar to the mRNA expression level except that the thalamus was higher than that of hypothalamus.The result of immunohistochemistry showed that VEGF-B protein-positive substances were mainly distributed in the cytoplasm of various types of cells.Among them,the positive staining of VEGF-B was mainly concentrated in eosinophils of pituitary.The positive staining of VEGF-B was mainly concentrated in pleomorphic cells of thalamus and hypothalamus.The distribution of VEGF-B protein-positive substances were mainly focused in nerve cell body of medulla oblongata and pons.Conclusion VEGF-B protein is expressed in both diencephalon and brainstem of yak,which may be closely related to its functions of anti-apoptosis,"survival factor"and angiogenesis.However,the specific mechanism of its neuroprotective effect on Yak brain under hypoxic environment needs to be further studied.The difference of expression in different regions may be related to the tissue specificity and function in different regions of the brain.