神经示踪作为一种神经解剖学研究的常用技术，有助于研究神经环路和轴突投射，周围神经损伤后的再生以及脊髓损伤后传导束的重建。荧光示踪剂可直接显示标记的神经元，无需后期染色，具备有：可特异性标记神经元，标记效率高，不易淬灭，可被快速运输到靶部位及低毒性等优点。
但目前能完全满足上述要求的荧光示踪剂并不多。苏州大学顾剑辉教授所在课题组进行的一项关于“Neurological function following intra-neural injection of fluorescent neuronal tracers in rats”的研究，建立了大鼠胫神经注射示踪剂模型，评价3种示踪剂Fluoro-Gold、True blue和Fluoro-Ruby对大鼠神经功能的影响。
结果证实，大鼠胫神经内注射Fluoro-Gold示踪剂可显著抑制运动、感觉和植物神经功能，注射Fluoro-Gold示踪剂对神经功能影响最严重，注射True blue示踪剂次之，而注射Fluoro-Ruby示踪剂基本对神经功能无影响。作者认为，文章结果是国际上从神经功能角度探讨示踪剂毒性的首次报道，可为未来研究神经重支配准确性提供理论基础。
文章发表在《中国神经再生研究（英文版）》2013年5月第14期的杂志上。（生物谷Bioon.com）
doi:10.3969/j.issn.1673-5374.2013.14.001
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Neurological function following intra-neural injection of fluorescent neuronal tracers in rats
Wen Hu1, 2, Dan Liu2, 3, Yanping Zhang2, 3, Zhongyi Shen2, 4, Tianwen Gu2, 4, Xiaosong Gu1, 2, Jianhui Gu3
Fluorescent neuronal tracers should not be toxic to the nervous system when used in long-term labeling. Previous studies have addressed tracer toxicity, but whether tracers injected into an intact nerve result in functional impairment remains to be elucidated. In the present study, we examined the functions of motor, sensory and autonomic nerves following the application of 5% Fluoro-Gold, 4% True Blue and 10% Fluoro-Ruby (5 μL) to rat tibial nerves via pressure injection. A set of evaluation methods including walking track analysis, plantar test and laser Doppler perfusion imaging was used to determine the action of the fluorescent neuronal tracers. Additionally, nerve pathology and ratio of muscle wet weight were also observed. Results showed that injection of Fluoro-Gold significantly resulted in loss of motor nerve function, lower plantar sensibility, increasing blood flow volume and higher neurogenic vasodilatation. Myelinated nerve fiber degeneration, unclear boundaries in nerve fibers and high retrograde labeling efficacy were observed in the Fluoro-Gold group. The True Blue group also showed obvious neurogenic vasodilatation, but less severe loss of motor function and degeneration, and fewer labeled motor neurons were found compared with the Fluoro-Gold group. No anomalies of motor and sensory nerve function and no myelinated nerve fiber degeneration were observed in the Fluoro-Ruby group. Experimental findings indicate that Fluoro-Gold tracing could lead to significant functional impairment of motor, sensory and autonomic nerves, while functional impairment was less severe following True Blue tracing. Fluoro-Ruby injection appears to have no effect on neurological function.
