经股后肌群注射DiI逆行示踪标记神经元胞体的实验研究

Retrograde tracing study on neurons labeled by injecting rear-thigh muscles with DiI in mice

目的探讨经股后肌群注射DiI行逆行示踪以精确显示支配神经元胞体在脊髓的时空分布情况。方法新生昆明小鼠65只，经左后肢股后肌群注射DiI，在注射2、4、6、8、12、24h和2、4、7、14、28d及2、3个月后观测背根神经节和腰段脊髓示踪荧光的分布和强度。结果①示踪细胞分布在左侧L2～S2脊髓段和相应的背根神经节，主要集中在L4～L6段；②注射DiI 6h后，在背根神经节和脊髓前角可见发微弱红色荧光的神经元；③标记的神经元数量逐渐增多，4d达到高峰；④6～24h每个标记神经元荧光逐渐增强，24h后达到高峰；⑤3个月后荧光强度无显著降低。结论经股后肌群注射DiI作逆行示踪，可快速、准确、持久地标记背根神经节感觉神经元和脊髓运动神经元，且适当延长示踪时间可提高神经元的标记率。

Objective To explore the fluorescent distribution, and the relation between fluorescent intensity and time after injecting rear-thigh muscles with DiI. Methods Sixty-five new born mice were equally and randomly divided into 13 groups. Fluorescent distribution and intensity were investigated at 2, 4, 6, 8, 12, 24 h, and 2, 4, 7, 14, 28 d and 2, 3 months after injecting the left posterior limb rear thigh muscles with 1.5 μl 4 mg/ml DiI for one mouse. Results The labeling neurons were scattered from L2 level to S2 level and associated dorsal root ganglion （DRG）, but the most were located at L4 to L6 section. The faint red fluorescence neurons were observed at dorsal root ganglion and cornu anterius medullae spinalis 6 h post-injection. The labeling neurons increased up to the 4th day. The fluorescent intensity enhanced gradually from 6 h to 24 h, then kept the intensity for 3 months. Conclusion It is a quick, precise, persistent method to trance and label the dorsal root ganglions sensory neuron and spinal motoneuron by injecting rear-thigh muscles with DiI, and the rate of labeling neurons can be improved by prolonging the tracing time properly. It is also provide basic data for clinical or experimental neuron label and location.