电针预处理对切口痛大鼠中脑导水管周围灰质5-HT7受体表达影响★

Effect of Electroacupuncture Preconditioning on the Expression of 5-HT7 Receptors in the Periaqueductal Grayof Rats with Incision Pain★

摘要:

目的 通过建立足趾部切口痛大鼠模型,探讨重复电针预处理对切口痛大鼠镇痛效果及其对中脑导水管周围灰质(PAG)5-HT₇受体(5-HT₇R)表达影响。方法 40只成年雄性SD大鼠随机均等分为对照组(C组)、模型组(M组)、预处理组(Y组)和实验组(S组)。M组和S组大鼠右足趾部行疼痛造模,且造模前,Y组和S组大鼠行右侧“足三里”穴和“环跳”穴电针刺激(2/10Hz疏密波,刺激强度为1,30min/d),连续5天。`于第一次电针预处理前2h(T1)、术前2h(T2)、术后4h(T3)、术后24h(T4)测定大鼠机械缩足反射阈值(MWT)和热缩足潜伏期(TWL)；酶联免疫吸附法检测脑脊液中5-HT浓度；免疫组化和免疫荧光方法分别检测大鼠PAG中c-Fos和5-HT₇R蛋白的表达情况。结果 与C组比较,M组大鼠T3、T4时间点的MWT和TWL均明显降低,脑脊液中5-HT浓度增加,PAG中c-Fos蛋白和5-HT₇R表达明显上调(P﹤0.05)；Y组脑脊液中5-HT含量和PAG中5-HT₇R表达上升(P﹤0.05)。与M组相比,S组大鼠T3、T4时间点的MWT和TWL显著升高,PAG中c-Fos蛋白表达减少,5-HT₇R蛋白表达增加(P﹤0.05)。结论 电针预处理可能是通过降低PAG中c-Fos蛋白含量、上调PAG中5-HT₇R蛋白表达发挥镇痛作用。

Abstract:

Objective To explore the analgesic effect of repetitive electroacupuncture preconditioning on incisional pain rats and its effect on the expression of 5-HT₇ receptors(5-HT₇R) in the periaqueductal gray(PAG) by establishing a rat model of toe incision pain. Methods Forty male SD rats were randomly divided into control group (Group C), model group (Group M), pretreatment group (Group Y), and experimental group (Group S). Operation was performed on the right toe of rats in Group M and Group S, and electroacupuncture was used to stimulate Zusanli and Huantiao points of the right leg of rats in Group Y and Group S for 5 days before operation (with the frequency of 2/10Hz, the intensity of 1, 30 minutes/day). The mechanical withdrawal threshold(MWT) and the thermal withdrawal latency(TWL) of rats were measured at 2 hours before the first electroacupuncture pretreatment(T1), 2 hours before the operation(T2), 4 hours after the operation(T3), and 24 hours after the operation(T4). After the last behavioral test, the brain tissue and cerebrospinal fluid of rats were taken out. The concentration of 5-HT in cerebrospinal fluid was measured by enzyme linked immunosorbent assay; immunohistochemical and immunofluorescence methods were used to detect the expression of c-Fos and 5-HT₇R proteins in PAG of rats respectively. Results Compared with group C, MWT and TWL of rats in group M decreased significantly at T3 and T4, while the concentration of 5-HT in cerebrospinal fluid increased, and the expression of c-Fos protein and 5-HT₇R in PAG increased significantly(P<0.05); the content of 5-HT in cerebrospinal fluid and the expression of 5-HT₇R in PAG increased in group Y(P<0.05). Compared with group M, MWT and TWL of rats in group S were significantly increased at T3 and T4, the expression of c-Fos protein in PAG was decreased, and the expression of 5-HT₇R protein was increased(P<0.05). Conclusion Electroacupuncture preconditioning may play an analgesic role by reducing the content of c-Fos protein in PAG, and upregulating the expression of 5-HT₇R protein in PAG.