霍乱毒素对视神经扎断后视网膜节细胞轴突再生的作用

The Effects of Cholera Toxin on the Axonal Regeneration of the Retinal Ganglion Cells After Microcrush of Optic Nerve

[目的]探讨霍乱毒素(CTx)对成年金黄地鼠视神经扎断(microcrush,MC)后视网膜节细胞(RGCs)轴突再生的促进作用。[方法]扎断成年金黄地鼠视神经近端,玻璃体内注射CTx,或插入小段坐骨神经分支(SN)。动物随机分为实验组和对照组:对照组分为单纯扎断视神经组(MC)和MC+溶剂组;实验组包括MC+CTx组、MC+CTx+SN组、量效关系组。量效关系组动物存活4周,其余各组动物存活3～5周。用荧光金逆行标记再生的RGCs,在荧光镜下观察视网膜平铺片再生 RGCs的数量变化。[结果]CTx不同剂量组125、250、500和1000 ng视网膜再生RGCs平均数分别为(130±46)、(189±91)、(358±84)、(94±34)个/视网膜,比MC组或MC+溶剂组显著增加,具有统计学意义(P<0.01),以500 ng/眼的剂量最佳。在3、4和5 W时MC+CTx组的视网膜再生RGCs平均数分别为(503±123)、(345±98)、(57±25)个/视网膜;MC+CTx+SN组为(771±199)、(432±105)、(160±76)个/视网膜,均比MC组或MC+溶剂组明显增加(P<0.01)。[结论]提示霍乱毒素或联合玻璃体内植入坐骨神经具有显著促进视神经扎断后视网膜节细胞轴突再生的作用。

[Objective] To investigate the effects of cholera toxin (CTx) on promoting the axonal regeneration of retinal ganglion cells (RGCs) of optic nerve after microcrush in adult hamster retina. [Methods] After microcrush of optic nerve. CTx was injected or (and) a small segment of autologous sciatic nerve branch (SN) was inserted intravitreously. Animals were randomly divided into regenerating control groups (MC group and MC+ solution group) and experimental groups (MC+ CTx, MC + CTx + SN, Effect and Dosage) . Animals in each group were allowed to survive for 3-5 weeks except for the Effect and Dosage group for 4 weeks. The regenerated RGCs were labeled retrogradely with f luorogold, and the number of regenerating RGCs in each retina were observed under fluorescent microscope. [Results] The mean numbers of regenerating RGCs in CTx different dose groups(125, 250, 500 and 1 000 ng) were (130±46) 、(189±91)、(358±84)、(94±34) respectively. All increased and were significantly higher than those in MC group and solution group( P <0.01) . The best does was 500 ng each eye. At 3, 4 and 5 weeks, the mean numbers of regenerating RGCs in MC+ CTx were (503±123) 、(345±98)、(57±25) respectively, and in MC + CTx + SN group were (771±199) 、(432±105)、(160 ±76) respectively. All increased and significantly higher than those in MC group and MC+ solution group at each time point ( P <0.01). [Conclusion] Our results indicate that injec- tion of CTx in combination with insertion of SN intravitreously can remarkably enhance the axonal regeneration of RGCs of optic nerve after microcrush.