人参皂甙-Rd对SNI大鼠痛敏异常及孤束核内P物质和NK-1受体表达的影响

Effects of Ginsenoside-Rd on the allodynia and the expression of substance P and NK-1 receptor in the solitary nucleus of rats with spared nerve injure

目的:通过观察人参皂甙-Rd(G-Rd)对坐骨神经分支选择损伤(spared nerve injure,SNI)大鼠痛敏异常及延髓内脏带孤束核内P物质(substance P,SP)和NK-1受体表达的影响,探讨G-Rd的镇痛机制。方法:成年雄性SD大鼠30只,随机分为五组:空白对照组(blank control)、假手术组(sham operation)、SNI组、SNI+saline组(腹腔注射,i.p.)、SNI+G-Rd组(i.p.)。行为学检测应用von Frey纤维测定上述各组大鼠手术侧后肢机械缩足反射阈值(paw withdrawal mechanical thresholds,PWMT);用免疫荧光组织化学染色法,在激光扫描共聚焦显微镜下,对比检测上述各组间孤束核(NTS)内SP样免疫阳性产物和NK-1样免疫阳性产物的平均荧光强度(mean flu-orescent intensity,MFI)。结果:SNI模型组术后10 d,手术侧后肢的PWMT值(4.63 g)明显低于正常对照组和假手术组(18.20～20.30 g),术后20 d达到最低阈值(2.38 g);而SNI+G-Rd组的PWMT值(4.67 g)则明显高于SNI组和SNI+saline组(P<0.05)。免疫荧光染色结果显示:术后20 d时,SNI组NTS内SP样和NK-1样免疫荧光的平均强度明显高于空白对照组和假手术组(P<0.05);但SNI+G-Rd组的SP样和NK-1样免疫荧光的平均强度则明显低于SNI组和SNI+saline组(P<0.05)。结论:人参皂甙-Rd可以明显改善SNI引起的痛敏异常,其机制之一可能与其有效减少NTS内SP和NK-1受体的表达有密切关系。

Objective： To investigate the expression of substance P and NK-1 receptor and the effect of the solitary nu- cleus on the analgesis of Ginsenoside-Rd（G-Rd） on neuropathic pain induced by spared nerve injure （SNI） , and to probe, the probable mechanisms. Methods： Thirty male SD rats were randomly divided into five groups： blank control, sham operation, SNI, SNI ＋ saline （intra-peritoneal injection, i. p. ）, SNI ＋ G-Rd （i. p. ） groups. We measured paw with- drawal mechanical thresholds （PWMT） using calibrated yon Frey filaments to stimulate the glabrous surface of the lateral plantar of the hindpaw. Immunofluorescent staining was used to measure the mean fluorescent intensity （MFI） of anti-SP- like and anti-NK-1 receptor-like fluorescent immunoreactivities in the solitary nucleus（NTS） of five groups under the con- focal laser scanning microscope. Results： On 10 days after SNI, the mean PWMT value （4.63 g） on SNI side was detec- ted clearly lower than that of the blank control and sham operation groups（ 18.20 -20.30 g） , and dropped to the lowest at 20 days （2.38 g）. The PWMT value of SNI ＋ G-Rd group （4.67 g） was significantly higher compared with that of SNI and SNI ＋ saline groups （P 〈 0.05）. The immunofluorescent staining results showed that the MFI of SP-like and NK-1 receptor-like immunoreactivities in NTS of SNI group was significantly higher compared with that of the blank control and the sham operation groups （P 〈 0.05）. But in SNI ＋ G-Rd group, the MFI of SP-like and NK-1 receptor-like immunore- activities observed clearly lower than that of SNI and SNI ＋ saline groups （ P 〈 0.05 ）. Conclusion： The G-Rd revealed obvious analgesic effect on neuropathic pain induced by SNI. The expressional decrease of SP and NK-1 receptor in NTS may be involved in one of mechanism of G-Rd inhibited the neuropathic pain.