目的 探究神经连接蛋白1 (NL1)在大鼠脊髓损伤后不同时间表达的变化。方法 成年雌性Sprague-Dawley大鼠60只随机分为假手术组(n=30)和实验组(n=30),每组再等分为3 d、7 d、14 d、21 d和28 d亚组。假手术组行T9-11椎板切除术,实验组用Allen打击仪 (10 g×25 mm)制造T10脊髓损伤模型。术后相应时间点行BBB评分,Golgi-Cox染色观察损伤中心上端脊髓白质树突及树突棘变化,免疫荧光染色检测NL1在损伤中心上端脊髓白质中的表达。结果 与假手术组相比,实验组各时间点BBB评分均显著降低(P<0.001);脊髓白质树突逐渐减少,树突棘密度逐渐降低(P<0.001);NL1于损伤后3 d开始升高,至14 d时达到峰值(P<0.05)。结论 NL1在脊髓损伤后自发性升高,但不足以诱导突触再生。
Objective To observe the change of expression of neuroligin1 (NL1) in injured spinal cord in rats.Methods A total of 60 adult female Sprague-Dawley rats were randomly divided into control group (n=30) and experiment group (n=30), and both groups were further arranged into three days, seven days, 14 days, 21 days, and 28 days subgroups. The control group accepted T9-11 laminectomy, while the experiment group was injured at T10 spinal cord hit by Allen's technique (10 g×25 mm). They were assessed with Basso, Beattie & Bresnahan locomotor rating scale (BBB scale), in their time-points, while Golgi-Cox staining was used to observe the variation of dendrites and density of dendritic spine in the white matter located at upper end of spinal cord injured center, and immunofluorescence staining was used to detect the expression of NL1.Results The score of BBB scale reduced in the experiment group compared with that in the control group in every subgroup (P<0.001). Compared to the control group, both dendrites and density of dendritic spine in the white matter decreased with time after injury (P<0.001), while the level of NL1 increased three days after injury, peaked on the 14th day after injury (P<0.05).Conclusion NL1 increases spontaneously after spinal cord injury, but it is not enough to promote synaptic regeneration.
[1] Shah RR, Tisherman SA. Spinal Cord Injury [M]// Falter F, Screaton NJ. Imaging the ICU Patient. London: Springer, 2014: 377-380.
[2] Freria CM, Hall JCE, Wei P, et al. Deletion of the fractalkine receptor, CX3CR1, improves endogenous repair, axon sprouting, and synaptogenesis after spinal cord injury in mice [J]. J Neurosci, 2017, 37(13): 3568-3587.
[3] Deng LX, Deng P, Ruan Y, et al. A novel growth-promoting pathway formed by GDNF-overexpressing Schwann cells promotes propriospinal axonal regeneration, synapse formation, and partial recovery of function after spinal cord injury [J]. J Neurosci, 2013, 33(13): 5655-5667.
[4] Bottos A, Rissone A, Bussolino F, et al. Neurexins and neuroligins: synapses look out of the nervous system [J]. Cell Mol Life Sci, 2011, 68(16): 2655-2666.
[5] Maćkowiak M, Mordalska P, Wędzony K. Neuroligins, synapse balance and neuropsychiatric disorders [J]. Pharmacol Rep, 2014, 66(5): 830-835.
[6] Krueger DD, Tuffy LP, Papadopoulos T, et al. The role of neurexins and neuroligins in the formation, maturation, and function of vertebrate synapses [J]. Curr Opin Neurobiol, 2012, 22(3): 412-422.
[7] Schapitz IU, Behrend B, Pechmann Y, et al. Neuroligin 1 is dynamically exchanged at postsynaptic sites [J]. J Neurosci, 2010, 30(38): 12733-12744.
[8] Kwon HB, Kozorovitskiy Y, Oh WJ, et al. Cortical synaptogenesis and excitatory synapse number are determined via a neuroligin-1-dependent intercellular competition [J]. Nat Neurosci, 2012, 15(12): 1667.
[9] Soler-Llavina GJ, Fuccillo MV, Ko J, et al. The neurexin ligands, neuroligins and leucine-rich repeat transmembrane proteins, perform convergent and divergent synaptic functions in vivo [J]. Proc Natl Acad Sci USA, 2011, 108(40): 16502-16509.
[10] Feng P, Akladious AA, Hu Y. Hippocampal and motor fronto-cortical neuroligin1 is increased in an animal model of depression [J]. Psychiatry Res, 2016, 243: 210-218.
[11] Suzuki K, Hayashi Y, Nakahara S, et al. Activity-dependent proteolytic cleavage of neuroligin-1 [J]. Neuron, 2012, 76(2): 410-422.
[12] Budreck EC, Kwon OB, Jung JH, et al. Neuroligin-1 controls synaptic abundance of NMDA-type glutamate receptors through extracellular coupling [J]. Proc Natl Acad Sci USA, 2013, 110(2): 725-730.
[13] Heikkinen A, Pihlajaniemi T, Faissner A, et al. Neural ECM and synaptogenesis [J]. Prog Brain Res, 2014, 214: 29-51.
[14] Giannone G, Mondin M, Grillo-Bosch D, et al. Neurexin-1β binding to neuroligin-1 triggers the preferential recruitment of PSD-95 versus gephyrin through tyrosine phosphorylation of neuroligin-1 [J]. Cell Rep, 2013, 3(6): 1996-2007.
[15] Smith GM, Strunz C. Growth factor and cytokine regulation of chondroitin sulfate proteoglycans by astrocytes [J]. Glia, 2005, 52(3): 209-218.
[16] Garland P, Broom LJ, Quraishe S, et al. Soluble axoplasm enriched from injured CNS axons reveals the early modulation of the actin cytoskeleton [J]. PLoS One, 2012, 7(10): e47552.
[17] David S, Kroner A. Repertoire of microglial and macrophage responses after spinal cord injury [J]. Nat Rev Neurosci, 2011, 12(7): 388.
[18] Matsushita T, Lankford KL, Arroyo EJ, et al. Diffuse and persistent blood-spinal cord barrier disruption after contusive spinal cord injury rapidly recovers following intravenous infusion of bone marrow mesenchymal stem cells [J]. Exp Neurol, 2015, 267: 152-164.
[19] Südhof TC. Synaptic neurexin complexes: a molecular code for the logic of neural circuits [J]. Cell, 2017, 171(4): 745-769.
[20] Poulopoulos A, Aramuni G, Meyer G, et al. Neuroligin 2 drives postsynaptic assembly at perisomatic inhibitory synapses through gephyrin and collybistin [J]. Neuron, 2009, 63(5): 628-642.
[21] Südhof TC. Neuroligins and neurexins link synaptic function to cognitive disease [J]. Nature, 2008, 455(7215): 903.
[22] Craig AM, Kang Y. Neurexin-neuroligin signaling in synapse development [J]. Curr Opin Neurobiol, 2007, 17(1): 43-52.
[23] Darian-Smith C. Synaptic plasticity, neurogenesis, and functional recovery after spinal cord injury [J]. Neuroscientist, 2009, 15(2): 149-165.
[24] Xu J, Xiao N, Xia J. Thrombospondin 1 accelerates synaptogenesis in hippocampal neurons through neuroligin 1 [J]. Nat Neurosci, 2010, 13(1): 22-24.
[25] Liauw J, Hoang S, Choi M, et al. Thrombospondins 1 and 2 are necessary for synaptic plasticity and functional recovery after stroke [J]. J Cerebr Blood F Met, 2008, 28(10): 1722-1732.
