牦牛小脑不同区域神经营养素-4及其受体的表达特征与定位研究

Expression Characteristics and Localization of Neurotrophin-4and Its Receptor in Various Regions of Yaks Cerebellum

神经营养素-4(NT-4)及其神经营养性酪氨酸激酶受体2(NTRK2)在小脑神经元存活、生长以及功能方面发挥着重要作用。为探讨NT-4和NTRK2在牦牛高原低氧适应中的作用,本研究以高原牦牛(Bos grunniens)和平原黄牛(Bos taurus)小脑为研究对象,采用实时荧光定量PCR(qRT-PCR)、蛋白免疫印迹技术(WB)、苏木精-伊红染色(HE)和免疫组织化学(IHC)对NT-4和NTRK2在牦牛与黄牛小脑不同区域中的表达分布进行分析。qRT-PCR和WB结果表明,NT-4基因和蛋白在牦牛小脑半球皮质中表达量最高,显著高于其他组织(P<0.05);NTRK2基因和蛋白在牦牛小脑蚓部皮质中表达量最高,显著高于其他组织(P<0.05)。与黄牛相比,牦牛NT-4蛋白在小脑各区域中的表达均显著高于黄牛(P<0.05);牦牛NTRK2蛋白在蚓部髓质和小脑半球髓质中的表达量低于黄牛或无差异,其余区域均显著高于黄牛(P<0.05)。IHC结果显示,NT-4和NTRK2蛋白阳性表达特征基本一致,皮质区主要分布于分子层的篮状细胞、浦肯野细胞层以及颗粒细胞层,而髓质区则散在分布于神经胶质细胞以及神经纤维中。由上述结果可知,NT-4和NTRK2在小脑各区域的表达差异可能与其参与脑组织生理功能以及适应高原低氧环境有关。在低氧环境下,NT-4和NTRK2通过上调激活相关通路以发挥内源性神经保护作用,进而保护脑组织免受低氧损伤。本研究结果可为探究牦牛脑组织低氧适应机制提供基础。

Neurotrophin-4(NT-4)and its neurotrophic receptor,Tyrosine Kinase Receptor 2(NTRK2),play significant roles in the survival,growth and functionality of cerebellar neurons.To investigate the roles of NT-4 and NTRK2 in the adaptation to high-altitude hypoxia in yaks(Bos grunniens),this study examined the expression levels and localization patterns of NT-4 and NTRK2 in different regions of the cerebellum of yaks and plain cattle(Bos taurus)using quantitative real-time PCR(qRT-PCR),Western blot(WB),Hematoxylin-Eosin(HE)staining and immunohistochemistry(IHC).qRT-PCR and WB results revealed that the expression of NT-4 gene and protein was the highest in the cerebellar hemisphere cortex of yaks,significantly higher than those in other tissues(P<0.05).NTRK2 gene and protein has the highest expression in the cerebellar vermis cortex of yaks,significantly higher than in other tissues(P<0.05).Compared to plain cattle,the expression of NT-4 protein in all areas of the yak cerebellum was higher(P<0.05).Yak NTRK2 protein in the vermis medulla was lower than in cattle,but significantly higher in all other areas(P<0.05).IHC results indicated that the positive expression of NT-4 and NTRK2 proteins was consistent,primarily distributed in Purkinje cell layer and granule cell layer in the cortex regions,while sparsely distributed in glial cells and nerve fibers in the medullary substance.These results suggest that the differential expression of NT-4 and NTRK2 in various cerebellar regions may be related to their involvement in the normal physiological functions of brain tissue and adaptation to high-altitude hypoxia.Under hypoxia conditions,NT-4 and NTRK2 likely activate relevant pathways to exert an endogenous neuroprotective effect,thereby safeguard brain tissue from hypoxia damage.This study provides a basis for exploring the mechanisms of hypoxia adaptation in yak brain tissue.