丙戊酸钠对 EAE 大鼠的治疗作用及其免疫调节机制

Effects of valproic acid on rats with experimental autoimmune encephalomyelitis and its immuno-modulatory mechanism

目的：探讨丙戊酸钠（ VPA）对实验性自身免疫性脑脊髓炎（ EAE）大鼠发病的影响及其免疫调节机制。方法50只雌性SD大鼠随机分为5组：空白对照组、EAE组、VPA低剂量组（100 mg/kg）、VPA中剂量组（300 mg/kg）和VPA高剂量组（600 mg/kg）。采用豚鼠脊髓匀浆免疫大鼠建立EAE模型，从免疫当天开始每日2次分别给予腹腔注射上述3种不同剂量的VPA或生理盐水，直到发病高峰期处死。观察大鼠行为学变化进行临床症状评分；采用苏木素-伊红染色观察中枢神经系统（CNS）内炎性细胞浸润；采用免疫组化观察CNS内小胶质细胞表达；用酶联免疫吸附法（ELISA）检测CNS内IFN-γ、IL-17和IL-10的含量。结果与EAE组比较，大、中、小剂量VPA组大鼠EAE发病率下降，临床症状减轻，潜伏期延长，CNS内炎性细胞浸润减少，但仅中剂量VPA组在EAE临床症状改变方面差异有统计学意义（P＜0．05），而中剂量和高剂量组病理学改变差异均有统计学意义（P＜0．05）；免疫组化结果显示，与EAE组比较，中剂量和高剂量VPA组的活化的小胶质细胞数量显著减少（P＜0．05）；ELISA结果显示，与EAE组比较，VPA干预后，大脑和腰髓中的IL-10水平上升而IFN-γ和IL-17水平明显减少，中剂量VPA组最为显著（ P＜0．05）。结论 VPA对EAE大鼠具有神经保护作用，中剂量最为显著，其作用机制可能与免疫调节作用有关。

Objective To investigate the effects of valproic acid （ VPA ） on SD rats with experimental autoimmune encephalomyelitis （ EAE） and its possible immunomodulatory mechanism .Meth-ods Fifty female Sprague-Dawley （ SD） rats were randomly divided into five groups by random digit table , including control group （n=10）, EAE group（n=10）, low dose VPA treated group （100 mg/kg, n=10）, median dose VPA treated group （300 mg/kg, n=10） and high dose VPA treated group （600 mg/kg, n=10）.The SD rat model of EAE was induced by immunizing with a guinea pigs′spinal cord homogenate （GPSCH）.Normal saline and various doses of VPA were given to rats in according groups twice a day from day 0 to day 19 （ close to the peak stage of EAE ） .The severity of EAE was scored according to the signs and symptoms.Pathological changes were observed through Hematoxylin-Eosin staining, and then the degrees of inflammatory infiltration were evaluated .The numbers of activated neuroglia that expressed Iba-1 in cerebral and lumber cords were counted by immunohistochemistry .The expression of IFN-γ, IL-17 and IL-10 in cer-ebral and lumber cords were measured by ELISA .Results Compared with EAE group , rats in the low, me-dian and high dose VPA treated groups had lower incidence of EAE and prolonged latency , but only the me-dian dose treated group showed significant alleviation in clinical symptoms （P〈0.05）.Both the median and the high dose treated group showed decreased inflammatory cell infiltration in CNS （P〈0.05）.Immunohisto-chemistry results showed that the numbers of activated microglia were significantly inhibited in rats treated with median and high dose of VPA in comparison with those in EAE group （P〈0.05）.Results of ELISA demonstrated that the expression of IFN-γand IL-17 in both median and high dose VPA treated groups were significantly decreased compared with those in EAE group （P〈0.05）, but only the median dose treated＆amp;nbsp;group showed a remarkably increased expression of IL-10 （P〈0.05）.Conclusion VPA, especially medi-um dose of VPA （ 300 mg/kg ） , had neuroprotective effects on rats with EAE .The possible mechanism might be associated with the inhibited activation of microglia and the increased percentage of anti -inflammato-ry cytokines .