大鼠脊髓损伤后表皮生长因子受体在脊髓的表达特点

目的研究大鼠脊髓损伤(spinal cord injury,SCI)后表皮生长因子受体(epidermal growth factor re-ceptor,EGFR)在脊髓的表达特点及意义。方法健康成年雄性SD大鼠,随机分为4组(每组10只):假手术组,SCI术后3 d、7 d和14 d组。应用Basso Beattie Bresnahan(BBB)评分观察大鼠行为学改变;逆转录-聚合酶链反应(RT-PCR)检测损伤段脊髓组织中EGFR mRNA表达水平;免疫组织化学方法观察损伤段脊髓灰质中EGFR蛋白表达情况;并对EGFRmRNA及蛋白表达情况与BBB评分进行相关性分析。结果行为学观察发现大鼠脊髓损伤后下肢神经功能逐步恢复;RT-PCR结果显示EGFR mRNA在假手术组大鼠脊髓中微量表达,SCI术后3 d表达显著升高,随后趋于下降,14 d时仍高于假手术组(P<0.01);免疫组织化学染色显示损伤段脊髓灰质中EGFR阳性细胞数在损伤后3 d显著高于假手术组(P<0.01),随后趋于下降,但14 d时仍高于假手术组(P<0.01);EGFR mRNA及蛋白的表达均与BBB评分呈显著负相关(r=-0.956,P<0.05;r=-0.966,P<0.05)。结论EGFR在大鼠脊髓损伤后具有时相分布特点,且与动物行为呈负相关,提示其表达可能阻碍损伤后的神经功能恢复。

EXPRESSIONAL CHARACTERISTICS OF EPIDERMAL GROWTH FACTOR RECEPTORS AFTER SPINAL CORD INJURY IN RATS

Objective To study the expressional characteristics and significance of epidermal growth factor receptors(EGFR) after spinal cord injury(SCI) in rats.Methods Male adult SD rats were randomly divided into four groups(10 for each group),the sham operation group,and the SCI 3d,7d and 14d groups.The changes of behavior were detected by Basso Beattie Bresnahan(BBB) scores,while the expressions of EGFR mRNA and protein in injured spinal cords were detected using RT-PCR and immunohistochemical staining respectively.Results In behavior examination,there was a trend of nerve functional recovery in injured rats.The result of RT-PCR demonstrated that the EGFR mRNA expression was slight in the sham group,but significantly increased in the SCI 3d group and then gradually decreased,though still higher on the 14th day than in the sham group(P < 0.01).Upon immunohistochemical staining,the expression of EGFR was greatly increased on the 3rd day after SCI compared with that of the sham group(P< 0.01),and then tended to decline,but still higher on the 14th day than that of the sham group(P< 0.01).Both EGFR mRNA and protein had significantly negative correlation with BBB scores.(r =-0.956,P<0.05;r =-0.966,P< 0.05).Conclusion The EGFR expression with phase characteristics after SCI,which negatively correlated with BBB scores,may limit nerve functional recovery after SCI.