七叶皂苷对大鼠三叉神经痛的改善作用

Ameliorative effect of escin on pain with trigeminal neuralgia in rats

目的:研究七叶皂苷(escin)对大鼠三叉神经痛(trigeminal neuralgia,TN)的治疗作用,并探讨其潜在的作用机制。方法:通过对大鼠行眶下神经慢性缩窄性损伤(chronic constriction injury of the infraorbital nerve,CCI-ION)的方式来构建大鼠TN模型。将大鼠随机分为假手术组(sham组)、CCI-ION组、CCI-ION+卡马西平(carbamazepine,CBZ;42 mg/kg)组和escin低、中、高剂量(6、12、24 mg/kg)组。手术当天开始灌胃给药,连续治疗14 d,sham组和CCI-ION组给予等剂量0.9%氯化钠溶液;使用Von Frey纤维细丝检测大鼠术侧口面部机械痛阈;实时定量聚合酶链反应(real-time quantitative polymerase chain reaction,RT-qPCR)检测三叉神经节(trigeminal ganglion,TG)中肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)、白细胞介素-1β(interleukin-1β,IL-1β)、Toll样受体-4(Toll like receptor-4,TLR-4)和核因子-κB(nuclear factor kappa-B,NF-κB)mRNA的表达变化;苏木精-伊红(hematoxylin and eosin,HE)染色观察TG的病理变化。结果:行为学结果显示,与sham组相比,CCI-ION组大鼠的机械疼痛阈值显著下降(P<0.01);与CCI-ION组相比,各给药组大鼠机械疼痛阈值在给药第3天后逐渐提高,至第14天时,所有给药组机械疼痛阈值均显著增高(P<0.01)。RT-qPCR结果显示,与sham组相比,CCI-ION组TNF-α、IL-1β、TLR-4及NF-κB m RNA的表达显著增加(P<0.01);与CCI-ION组相比,各给药组TNF-α、IL-1β、TLR-4及NF-κB mRNA的表达显著降低(P<0.05)。组织病理学结果显示,与sham组相比,CCI-ION组观察到TG出现明显的炎性细胞浸润、施万细胞数增多及脱髓鞘的变化;与CCI-ION组相比,各给药组光学显微镜下可见TG炎症情况有不同程度的减轻。结论:Escin对CCI-ION诱导的TN有一定的改善作用,其机制可能与促炎细胞因子释放的下调有关,并可能通过TLR4/NF-κB信号通路发挥作用。

Objective:To investigate the effect of escin on trigeminal neuralgia(TN)and its potential mechanism.Methods:Chronic constriction injury of the infraorbital nerve(CCI-ION)was used to establish TN model in rats.Rats were divided into six groups:Sham group,CCI-ION group,CCI-ION+carbamazepine(CBZ,42 mg/kg)group,low-dose escin(6mg/kg)group,medium-dose escin(12 mg/kg)group and high-dose escin(24 mg/kg)group.Intragastric administration was started from the day of surgery for consecutive 14 days,and sham group and CCI-ION group were given equal dose of saline.Von Frey test was used to detect the facial mechanical allodynia of rats.The mRNA of tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β),Toll like receptor-4(TLR-4)and nuclear factor kappa-B(NF-κB)in trigeminal ganglion(TG)was detected by real-time quantitative polymerase chain reaction(RT-qPCR).Hematoxylin and eosin(HE)staining was used to observe the pathological changes of TG.Results:Behavioral results showed that compared with the sham group,mechanical pain threshold of rats in CCI-ION group decreased significantly(P<0.01);compared with the CCI-ION group,the mechanical pain threshold of rats in each drug administration group began to increase gradually since the 3rd day of drug administration,and significantly increased in all drug administration groups on the 14th day after gavage(P<0.01).RT-qPCR results showed that compared with the sham group,mRNA expression of TNF-α,IL-1β,TLR-4 and NF-κB significantly increased in CCI-ION group(P<0.01);compared with the CCI-ION group,mRNA expression of TNF-α,IL-1β,TLR-4 and NF-κB in all treatment groups significantly decreased(P<0.05).Histopathological results showed that compared with the sham group,significant inflammatory cell infiltration and increase of Schwann cell number and demyelina-tion changes were observed in TG of CCI-ION group under light microscope;compared with the CCI-ION group,the inflammation situation of TG was alleviated to varying degrees in each drug administration group.Conclusion:Escin can alleviate TN induced by CCI-ION,and its mechanism may be related to down-regulation of pro-inflammatory cytokines,and may play a role through TLR-4/NF-κB signaling pathway.