| Objective: To evaluate the effects of axonal outgrowth of dorsal root ganglion neurons(DRGNs) treated with Y27632 and Taxol in extracts of injured spinal cord in newborned SD rats. Methods: ① 21 adult female SD rats were randomly divided into 3 groups and there were 7 in control group, 7 in operation group and 7 in sham operation group. The model of completely spinal cord injury of SD rats with complete paralysis below T9 level were made by modified Allen method. The spinal cord of T8-T10 level were harvested to prepare tissue homogenate by separation,filtration and the same spinal tissue homogenatewere obtained in control group and sham operation group respectively at 1 week after spinl cord injury .② The DRGNs of new borned SD rats obtained by seperation, primary culture and identification.③Experiment one: the mean length of axonal outgrowth and mean fluorescence density at distal outgrowth axonal of DRGNs were measured in different groups respectively at 2 days after co -culture (group A: DRGNs+50μl PBS, group B:DRGNs+50μlextractes of normal spinal cord in control group, group C:DRGNs+50μl extractes of normal spinal cord in sham operation group, group D: DRGNs+50μl extractes of injured spinal cord in operation group).Experiment two: the mean length of axonal outgrowth and mean fluorescence density at distal outgrowth axonal of DRGNs were measured in different groups respectively at 1day,2 days after co -culture with Y27632,Taxol and Y27632+Taxol ( group A: DRGNs+50μlPBS, group B: DRGNs+50μl extractes of injured spinal cord, group C: DRGNs+50μl extractes of injured spinal cord+3nM Taxol. group D: DRGNs+50μl extractes of injured spinal cord+30μM Y27632. group E:DRGNs+50μl extractes of injured spinal cord+30μM Y27632+3nM Taxol) . Results:①In experiment one: The mean length of axonal outgrowth at 2 days was 142. 1±5.7μm in group A,144.8±3.1 μm in group B,47.2±3.5μm in group C and 136.9±4.2μm in group D respectively and the length of axonal outgrowth in group C was significantly longer than it in group A, group B and group C respectively by one-way ANOVA analysis of variance (p<0. 01). The mean fluorescence density at distal axonal outgrowth of DRGNs at 2 days was 175.1±2.9AFU/μm in group A,174.8±3.1 AFU/μm in group B, 191.6±3.1 AFU/μm in group C,64.5±1.5AFU/μm in group D respectively and the mean fluorescence density at distal axonal outgrowth of DRGNs in group C was significantly less than it in group A,group B and group D respectively by one-way ANOVA analysis of variance (p<0.01). In experiment two: The mean length of axonal outgrowth at 1day was 136.5±4.6μm in group A,47.6±3.9μm in group B, 137.9±5.2μm in group C, 158.6±4.6μm in group D, 181.2±5.2μm in group E respectively and the length of axonal outgrowth in group B was signifcantly shorter than it in group A, group C, group D, and group E respectively by one-way ANOVA analysis of variance (p<0. 0 1). The mean length of axonal outgrowth was 142.9± 1.4μm in group A,44.5±2.2μm in group B,152.6±5.3μm in group C,168.1 ±3.1μm in group D,194.6±3.2μm in group E respectively at 2 days and the mean length of axonal outgrowth in group B was significantly shorter than group A,group C,group D and group E respectively (p<0. 01) and it in group C was significantly shorter than it in group D, and in group E respectively (p<0. 05) and it in group E was significantly longer than it in group A, group B ,group C and group D respectively by one-way ANOVA analysis of variance (p<0. 0 1). The mean fluorescence density at distal axonal outgrowth of DRGNs was 181.8±3.4 AFU/um in group A,61.6±2.7AFU/um in group B , 205.2±2.1AFU/um in group C,401.2±3.5 AFU/um in group D,and 470.2±3.6 AFU/um in group E respectively at 2 days. The mean fluorescence density at distal axonal outgrowth of DRGNs in group B was significantly more than it in groupA,group C,group D,and group E respectively (p<0. O 1)and it in group E was significantly more than it in group A,group C,group D and group E respectively (p<0.01).Conclusions: ① The extracts of injured spinal cord could obviously inhibit s DRGNs axonal growth and it can simulates the microenvirment of spinal cord injury for central vervous system axon experiments in vitro. ② Combination of appropriate dose of Y27632 and Taxol could obviously promote axonal outgrowth a, enhance growth cone formation and induce to form multiple branches of DRGNs in newborned SD rats under injured spinal cord micro-environment. Although application of appropriate dose of Y27632, Taxol alone could also can does ,its effects is weaker than its of Y27632 + Taxol . |
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