FK506抑制脊髓挫伤后诱导型一氧化氮合酶表达的实验研究

Inhibitive effect of tacrolimus on expression of inducible nitric oxide synthase in rats following contusion spinal cord injury

目的观察大鼠脊髓挫伤后早期应用FK506对诱导型一氧化氮合酶(iNOS)表达的抑制作用。方法45只成年雄性大鼠随机分为假手术组、对照组和治疗组。治疗组在脊髓挫伤后5 min一次性经尾静脉注射FK506(0.3mg/kg),其余两组以相同方法给予0.9%生理盐水。伤后3,7,14,21 d采用BBB评分法进行后肢运动功能评价,应用逆转录聚合酶链反应(RT-PCR)和免疫组织化学染色检测iNOS的mRNA和蛋白质的表达,同时行脊髓组织尼氏染色病理学观察。结果治疗组病理学观察和行为学评分明显优于对照组(P<0.05,P<0.01);iNOS的mRNA和蛋白质的表达均于伤后7 d达高峰,两者表达在治疗组明显低于对照组(P<0.05,P<0.01)。结论FK506能抑制大鼠脊髓挫伤后iNOS表达,减轻继发性损害,从而改善脊髓损伤后的功能恢复。

Purpose To examine the inhibitive effect of tacrolimus on expression of inducible nitric oxide synthase （iNOS） in rats following contusion spinal cord injury （SCI）. Methods Forty-five male rats were divided randomly into three groups： the sham-operation group, the control group and the treatment group, and the latter two groups were subjected to contusion SCI at the T10 vertebrae level with a weight-drop impactor （10 g weight was dropped from a 4.0 cm height）. The treatment group was injected with tacrolimus 5 minutes after SCI, while the other groups received 0.9% saline likewise. The BBB scales were used to assess hind limb neurological function at 3,7,14,21 days after SCI. The expression of iNOS mRNA and protein was detected by using reverse transcription polymerase chain reactions （RT-PCR） and immunohistochemistry staining. The pathological changes in injured spinal cord were also observed with Nissl＇s staining. Results The pathological outcomes and behavioral score of the treatment group were significantly superior to those of the control group. The peak expressions of iNOS mRNA and protein were simultaneously observed at 7 days after SCI and the expressions were significantly lower in the treatment group than those in the control group. Conclusion Tacrolimus could inhibit expression of iNOS, mitigate secondary spinal cord damage and thus ameliorate function recovery following SCI.