左旋咪唑长期处理后对EAE大鼠咪唑啉2受体的影响

Effect of chronic treatment with levamisole on imidazoline I2 receptor in rats with experimentalautoimmune encephalomyelitis

目的探讨左旋咪唑（LMS）长期处理后对实验性自身免疫性脑脊髓炎（EAE）大鼠脑组织中咪唑啉2受体02g）数目及亲和力的影响。方法将30只Wistar大鼠按照随机数字表法分成3组：对照组（8只）、EAE组（10只）及EAE＋LMS组（12只），采用豚鼠脊髓匀浆免疫诱导建立EAE模型。对照组每只大鼠四足垫各皮下注射0．5mL生理盐水＋完全弗氏佐N（CFA）乳剂，并于免疫后第0小时及第1天开始每天连续腹腔注射0．4mL生理盐水，2次／d；EAE组大鼠四足垫皮下注射0．5mL脊髓匀浆＋CFA乳剂，余同对照组；EAE＋LMS组大鼠四足垫皮下注射O．5mL脊髓匀浆＋CFA乳剂．并于免疫后第0小时及第1天开始每天连续腹腔注射LMS（10mg／kg）。通过观察大鼠行为学变化进行临床症状评分：采用HE染色和监牢蓝髓鞘染色观察小脑和脊髓中的炎症细胞浸润和髓鞘脱失情况；采用受体-放射配体结合实验观察大脑及脑干中12R数目及亲和力的变化。结果与EAE组比较，EAE＋LMS组大鼠EAE发病率有下降趋势，临床症状减轻，潜伏期延长，中枢神经系统内炎性细胞浸润和髓鞘脱失减少。受体-放射配体结合实验结果显示EAE组大鼠脑组织中12R的最大结合数量（Bmax）[（266．1±28．13）frmol／mg]较对照组[（177．5±26．10）fmol／mg]明显增高，平衡解离常数（Kd）（5．307±1．107）较对照组（3．586±1．053）明显增大，差异均有统计学意义（P〈0．05）。与EAE组比较，EAE＋LMS组大鼠脑组织中I2R的Bmax值[（496．1＋52．31）fmol／mg]明显增高，差异有统计学意义（P〈0．05）；K值（6．781±1．168）亦增大，但差异无统计学意义（P〉0．05）。结论LMS长期处理后对EAE大鼠具有神经保护作用，其作用机制可能与12R的调节作用有关。

Objective To investigate the effects of chronic treatment with levamisole （LMS） on imidazoline I2 receptor （I2R） in rats with experimental autoimmune encephalomyelitis （EAE）. Methods Thirty female Wistar rats were randomly divided into three groups： control group （n=8）, EAE model group （n=10）, EAE＋LMS treatment group （n=12）; the rat models of EAE were induced by immunizing with guinea pigs spinal cord homogenate. Subcutaneous injection of 0.5 mL of normal saline＋complete Freund＇s adjuvant （CFA） emulsion was performed to rats in the control group, and 0 and 24 h after the that, intraperitoneal injection of 0.4 mL of saline twice daily was performed; subcutaneous injection of 0.5 mL of homogenate＋CFA emulsion was performed to rats in the EAE model group; subcutaneous injection of 0.5 mL of homogenate＋CFA emulsion was performed to rats in the EAE＋LMS treatment group, and 0 and 24 h after the that, intraperitoneal injection of LMS （10 mg/kg） twice daily was performed. The severity of EAE was scored according to the signs and symptoms. Pathological changes were observed through hematoxylin-eosin staining and Luxol-Fast blue dyeing, and the degrees ofinflammatory infiltration were evaluated. The maximal binding capacity （Bronx） and dissociation content （Kd） of I：R were measured by radioligand binding assay. Results As compared with rats in the EAE model group, rats in the EAE＋LMS treatment group had lower incidence of EAE, alleviated clinical symptoms, prolonged latency and decreased central nervous system inflammation. Radioligand binding assay showed that both the Bmax values and Kd constant of I2R （266.1±28.13 fmol/mg and 5.307±1.107） in the EAE model group were increased as compared with those in the control group （177.5±26.10 fmol/mg and 3.586±1.053, respectively）, with statistically significant differences （P〈0.05）. As compared with those in the EAE model group, the I2R Bmax values in the EAE＋LMS treatment group （496.1 ±52.31 frmol/mg） were markedly increased （P〈0.05）, but there were no significantly differences in Kd values of I：R between these two groups （P〉0.05）. Conclusion Chronic treatment with LMS has beneficial neuroprotective effect on rats with EAE, and its mechanism might be related to the regulation of I2R.