Yang Wei, Zhang Hao
Department of Physiology, Key Laboratory of Cellular Physiology, Ministry of Education, Shanxi Medical University, Taiyuan, China.
Key Laboratory of Ministry of Education, Shanxi Medical University, Taiyuan, China.
Brain Res. 2016 Jan 1;1630:1-9. doi: 10.1016/j.brainres.2015.10.042. Epub 2015 Oct 31.
The aim of the present study was to investigate the effects of hindlimb unloading (HU) on the expression of neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF), together with the expression of their high-affinity receptors tropomyosin receptor kinase C (TrkC) and tropomyosin receptor kinase B (TrkB), in lumbar (L4-6) segment of the spinal cord and in the soleus muscle. The mRNA and protein levels of the genes of interest were compared using quantitative PCR and western blot assays. Immunohistochemistry for NT-3 and BDNF was used to detect the levels of protein in the motoneurons in the lateral motor column. In this study, NT-3 and BDNF mRNA and protein expression were significantly increased in the spinal cord and soleus muscle after HU. NT-3 immunoreactivity, but not BDNF immunoreactivity, was significantly increased in the large motoneurons located in lateral motor column after 14 days of HU. The level of TrkC protein in the spinal cord and soleus muscle were significantly elevated after both 7 days and 14 days of HU. However, TrkC mRNA, TrkB mRNA and TrkB protein levels did not change significantly. Elevated BDNF, NT-3 and TrkC levels in the neuromuscular system indicate that neurotrophins are involved in HU-induced neuromuscular plasticity. NT-3 is a candidate to mediate the synaptic efficacy between alpha motoneurons and group Ia afferents.
本研究的目的是探讨后肢卸载（HU）对脊髓腰段（L4 - 6）和比目鱼肌中神经营养因子-3（NT-3）和脑源性神经营养因子（BDNF）的表达及其高亲和力受体原肌球蛋白受体激酶C（TrkC）和原肌球蛋白受体激酶B（TrkB）表达的影响。使用定量PCR和蛋白质印迹分析比较了相关基因的mRNA和蛋白质水平。采用NT-3和BDNF免疫组织化学方法检测外侧运动柱运动神经元中的蛋白质水平。在本研究中，HU后脊髓和比目鱼肌中NT-3和BDNF的mRNA及蛋白质表达显著增加。HU 14天后，位于外侧运动柱的大型运动神经元中NT-3免疫反应性显著增加，而BDNF免疫反应性未显著增加。HU 7天和14天后，脊髓和比目鱼肌中TrkC蛋白水平均显著升高。然而，TrkC mRNA、TrkB mRNA和TrkB蛋白水平没有显著变化。神经肌肉系统中BDNF、NT-3和TrkC水平升高表明神经营养因子参与了HU诱导的神经肌肉可塑性。NT-3是介导α运动神经元与Ia类传入纤维之间突触效能的一个候选因子。
