银杏叶提取物对大鼠脊髓损伤后神经细胞凋亡和一氧化氮合酶表达的影响

Effects of extract of Ginkgo bfloba on apoptosis of neurocytes and expression of inducible nitric oxide synthase after spinal cord injury in rats

目的探讨银杏叶提取物（extract of Ginkgo biloba，EGb）对脊髓损伤后神经细胞的保护作用及其机制。方法雌性SD大鼠48只，体重200—230g，用随机数字表法把大鼠分为等渗盐水组（NS组）24只，银杏叶提取物组（EGb组）24只。在T9椎板水平半切脊髓。术后NS组大鼠每天给予2ml等渗盐水灌胃，EGb761组大鼠每天给予2ml（20mg）EGb灌胃。分别于术后1，7，14，21d取材，行髓鞘染色、焦油紫染色、诱生型一氧化氮合酶（iNOS）免疫组化和TUNEL法标记凋亡细胞。结果术后各时相点EGb组大鼠脊髓损伤周围邻近区脱髓鞘明显减轻，坏死囊腔明显减小，损伤侧与正常侧脊髓前角神经元数目比率明显高于Ns组（P〈0．05），神经细胞凋亡指数和iNOS表达阳性细胞率低于NS组（P〈0．01或P〈0．05）；而且，iNOS阳性细胞率与细胞凋亡指数间呈正相关（r=0．729，P〈0．01）。结论EGb能减少脊髓损伤后神经细胞的凋亡，其机制可能与抑制iNOS表达有关。

Objective To investigate the effect of extract of Ginkgo biloba （EGb） on apoptosis of nerve cells and its mechanism after spinal cord injury （SCI） in rats. Methods Forty eight adult SD rats weighing 200-230 g were divided equally and randomly into EGb group and normal saline （NS） group. After hemiseetion of spinal cord at T9 vertebrae level, rats in EGb group were lavaged with 2 ml EGB （20 mg） daily and those in NS group with 2 ml NS daily. Tissue sections were collected and stained with Nissl＇ s staining, myelin sheath staining, and inducible nitric oxide synthase （iNOS） immunohistochemistry as well as terminal deoxynucleotidyl transferase-mediated dUTP nick end lebeling （TUNEL） at days 1,7, 14 and 21 respectively to evaluate the injured spinal cord tissues after six rats from each group were sacrificed Results Nissl＇ s staining manifested less swelling of the nerve cells near the injury epicenter （rostral and caudal）, smaller cavity and demyelinated area and higher ratio of bilateral anterior horn neurons of transection side to normal side in EGb group, compared with NS group （ P 〈 0.05 ）. Apoptotic index （AI） and expression of iNOS in NS group were higher than those in EGb group （P 〈 0.01 or P 〈 0.05 ）. Furthermore, the rate of iNOS-positive cells was positively correlated with the AI （ r = 0.729, P 〈 0.01 ） after SCI. Condusion EGb can prevent nerve cells from apoptosis after SCI in rats, as may be related with inhibition of expression of iNOS.