Central nervous system trans‐synaptic effects of acute axonal injury: a 1h magnetic resonance spectroscopy study
Central nervous system trans‐synaptic effects of acute axonal injury: a 1h magnetic resonance spectroscopy study
复制标题
急性轴突损伤的中枢神经系统跨突触效应：1 小时磁共振波谱研究
DOI：
--
复制
发表时间：
1995
影响因子：
3.3
通讯作者：
L. Zetta
中科院分区：
文献类型：
--
作者：
M. Rango;D. Spagnoli;G. Tomei;F. Bamonti;G. Scarlato;L. Zetta
N-乙酰天冬氨酸（NAA）以前曾被提议作为神经元标记物。1H磁共振波谱（1H magnetic resonance spectroscopy，1H MRS）可以检测到脑内NAA的含量，并且脑损伤后NAA的含量降低。这种减少的原因还没有完全理解，神经元损失损伤和“功能障碍”都被提出。假设急性中枢神经系统（CNS）去传入导致跨突触NAA减少，高分辨率1H MRS能够检测到这种减少。为了检验这一假设，使用了一个实验模型，其中通过豚鼠右侧视神经（95-99%交叉纤维）中的拉伸损伤获得轴突损伤。72 h后，通过高分辨率1H MRS测量外侧膝状体（LGB）和上级丘（SC）样本提取物中NAA、总肌酸（Cr）的跨突触浓度和NAA/Cr比值。在左侧LGB/SC（右侧视神经纤维投射的位置）中，发现NAA和NAA/Cr降低，而Cr水平正常。右侧LGB/SC的NAA、NAA/Cr和Cr值均正常，组织学和EM检查未见异常。第7天，左侧LGB/SC NAA和NAA/Cr值在正常范围内。得出的结论是：1）中枢神经系统的急性去传入导致NAA水平跨突触下降，这可以通过1H MRS检测到; 2）NAA下降可能是由于功能性神经元不活动而引起的NAA代谢变化，而不是神经元丢失、损伤或“功能障碍”。1H MRS是研究活体CNS损伤后功能效应的一种潜在工具。
N‐acetylaspartate (NAA) has previously been proposed as a neuronal marker. 1H magnetic resonance spectroscopy (MRS) is able to detect NAA in brain, and decreases of NAA have been documented after brain injury. The reason for this decrease is not fully understood and neuron loss damage and “dysfunction” have all been proposed. It is hypothesized that acute central nervous system (CNS) deafferentation causes a trans‐synaptic NAA decrease and that high resolution 1H MRS is able to detect such a decrease. To test this hypothesis, an experimental model was used in which axonal lesions were obtained by stretch injury in guinea pig right optic nerve (95–99% crossed fibers). The trans‐synaptic concentration of NAA, total creatine (Cr), and the NAA/Cr ratio in lateral geniculate bodies (LGB) and superior colliculi (SC) sample extracts were measured 72 h later by high resolution 1H MRS. In the left LGB/SC, which is where right optic nerve fibers project, reductions of NAA and NAA/Cr were found whereas Cr levels were normal. NAA, NAA/Cr, and Cr values were all normal in the right LGB/SC. Histology and EM findings revealed no abnormalities. At 7 days, left LGB/SC NAA and NAA/Cr values were in the normal range. It was concluded that 1) acute deafferentation in the CNS causes a trans‐synaptic decrease of NAA levels that can be detected by 1H MRS and 2) NAA decrease may be due to changes of NAA metabolism caused by functional neuronal inactivity rather than neuronal loss, injury or “dysfunction.” 1H MRS is a potential tool for the study of functional effect of CNS lesions in vivo.