17β-雌二醇对去势大鼠慢性脊髓损伤后神经保护作用的实验研究

EXPERIMENTAL STUDY ON NEUROPROTECTIVE EFFECT OF 17β-ESTRADIOL AFTER CHRONIC SPINAL CORD INJURY IN OVARIECTOMIZED RATS

目的探讨17β-雌二醇对去势大鼠慢性脊髓损伤后神经细胞凋亡的影响。方法取90只雌性Wistar大鼠,体重220～250 g,行双侧卵巢切除术;2周后将大鼠随机分为3组(n=30):假手术组(A组),慢性渐进性压迫性脊髓损伤加17β-雌二醇组(B组)、慢性渐进性压迫性脊髓损伤空白对照组(C组)。A组仅手术切除T10棘突;B、C组制备慢性渐进性压迫性脊髓损伤模型后,分别于造模后每周腹腔注射17β-雌二醇2次(每次100μg/kg)和相同剂量生理盐水。于造模后1、3、7、14、28、60 d采用改良Tarlov评分及斜板实验评分观察大鼠运动功能情况,取材后行HE染色、半胱氨酸蛋白酶3(Caspase-3)免疫组织化学染色及TUNEL染色观察。结果造模后14、28及60 d,B组改良Tarlov评分及斜板实验评分均优于C组,但低于A组,差异有统计学意义(P<0.05)。HE染色示,造模28 d B组镜下见脊髓灰质轻度水肿、神经元肿胀,有少量胶质细胞和星形胶质细胞增生,病理改变较C组减轻;60 d B组脊髓灰质轻度水肿、神经元肿胀均明显减轻。造模后14、28、60 d B组Caspase-3阳性细胞百分率显著低于C组,7、14、28、60 d B组细胞凋亡率显著低于C组,但均高于A组,差异均有统计学意义(P<0.05)。结论 17β-雌二醇能减少大鼠慢性脊髓损伤后神经细胞凋亡,促进神经功能恢复。

Objective To investigate the effects of 17β-estradiol on the cell apoptosis after chronic spinal cord injury in ovariectomized rats.Methods A total of 90 female Wistar rats（weighing,220-250 g） received removal of bilateral ovaries.After 2 weeks,the rats were randomly divided into 3 groups（n=30）： sham-operation group（group A）;chronic gradual spinal cord injury model and 17β-estradiol treatment group（group B）;and chronic gradual spinal cord injury model and normal saline treatment group（group C）.Rats of group A only received removal of spinous process at T10.Rats of groups B and C were made the models of chronic gradual spinal cord injury,and then 17β-estradiol（100？μg/kg,twice a week） and normal saline were given by peritoneal injection,respectively.The cell apoptosis and positive cells of Caspase-3 were examined by the TUNEL methods and Caspase-3 immunohistochemical staining at 1,3,7,14,28,and 60 days after modeling;and the neurological function was evaluated by Tarlov scale and inclined plane test scoring.Results At 14,28,and 60 days after modeling,Tarlov scale and inclined plane test scores of group B were significantly better than those of group C（P 0.05）,but were significantly lower than those of group A（P 0.05）.At 28 days after modeling,HE staining showed that the edema of spinal gray matter and the neurons,the proliferation of glial cells and astrocytes,and less pathologic change were observed in group B;and the pathological changes in group B were mitigated than in group C.At 60 days after modeling,edema of spinal gray matter and the neurons was significantly ameliorated in group B.At 14,28,and 60 days after modeling,the rate of Caspase-3 positive cells in group B was significantly lower than in group C（P 0.05）,but was significantly higher than in group A（P 0.05）.At 7,14,28,and 60 days after modeling,the cell apoptotic rate was significantly lower in group B than in group C（P 0.05）,but was significantly higher than in group A（P 0.05）.Conclusion 17β-estradiol can reduce the numbers of apoptotic cells and promote the nerve function recovery after chronic spinal cord injury of rats.