咪唑克生对实验性自身免疫性脑脊髓炎大鼠小胶质细胞激活和白介素17、肿瘤坏死因子α表达的影响

目的观察咪唑克生对实验性自身免疫性脑脊髓炎(EAE)大鼠脑组织中小胶质细胞、白介素17(IL-17)、肿瘤坏死因子α(TNF-α)表达的影响。方法 SD大鼠30只随机分成3组:EAE-咪唑克生组(免疫当日开始给予咪唑克生2 mg·kg~(-1),腹腔注射,连续14 d)、EAE-生理盐水组(给予相同剂量生理盐水)和空白对照组。用豚鼠全脊髓匀浆免疫诱导制作EAE大鼠模型。每天观察评估各组大鼠神经功能变化;苏木精-伊红染色观察病理学改变;免疫组化法检测小胶质细胞(Iba1阳性)的激活与表达水平;酶联免疫吸附试验(ELISA)法检测发病高峰期(免疫后15 d)脑组织中IL-17,TNF-α表达水平。结果与EAE-生理盐水组比较,EAE-咪唑克生组(1)日均神经功能评分降低(P0.05),最大临床症状评分显著降低(P0.01);(2)苏木精-伊红染色:中枢炎症细胞浸润减少(P0.05);(3)免疫组化:Iba1阳性细胞表达减少(P0.05);而EAE-生理盐水组大鼠腰髓内Iba1阳性细胞表达较空白对照组明显升高(P0.01);(4)ELISA:炎性细胞因子IL-17和TNF-α表达明显降低(P0.01)。结论咪唑克生能够减缓大鼠EAE病情,其机制可能与抑制中枢神经系统小胶质细胞激活,下调中枢神经系统炎症因子IL-17和TNF-α的表达,扰乱中枢神经系统内炎症因子的平衡有关。

Intervention Effects of Idazoxan on the Activation of Microglia and the Expression of Cytokines in the Central Nervous System of Rats with Experimental Autoimmune Encephalomyelitis

Aim To investigate the effects of idazoxan on experimental autoimmune encephalomyelitis (EAE) rats and the expression of Iba1, IL-17 and TNF-α in the central nervous system (CNS). Methods SD rats were randomly divided into three groups: a control group, a EAE-saline group and a EAE-idazoxan treated group. EAE was induced by immunizing SD rats with guinea pig spinal cord homogenates (GPSCH). Rats in EAE-idazoxan treated group were administrated with idazoxan for 14 days at the dose of 2 mg·kg-1 after immunization, and rats in EAE-saline group were treated with saline as the same dose as idazoxan. Rat's behavioral changes were measured twice daily after immunization until them were killed at the 15th day. The damage and the inifltration of inlfammatory cells in CNS were evaluated with HE stain. Immunohistochemistry (IHC) was used to determine the expression of Iba1. Expression levers of IL-17, TNF-α in CNS were quantified by ELISA.Results Compared with EAE-saline group, the severity of clinical score and the inifltration of inlfammatory cells (P<0.05) in CNS improved in EAE-idazoxan treated rats. IHC: EAE induced significant increase in the number of Iba1 expressing cells in the spina cord (P<0.01). Compared with the EAE-saline group, the number of Iba1 positive cells in EAE-Idazoxan group decreased (P<0.05). ELISA analysis showed that the expressions of IL-17 and TNF-α(P<0.01) decreased signiifcantly in the CNS in EAE-idazoxan treated rats compared with EAE-saline group rats.Conclusion Idazoxan had protective effects on EAE, which associated with the attenuated microglial activation and may be due to the down regulations of IL-17 and TNF-α, shifting the balance of inlfammatory cytokines.