Experimentally investigating the effect of buccal acupuncture on analgesic time-effect characteristics and monoamine neurotransmitters

Abstract

Objective

To investigate the analgesic time-effect characteristics and changes in concentrations of rabbit’s hypothalamic 5-hydroxytryptamine (5-HT) and noradrenaline (NE) caused by buccal acupuncture in the rheumatoid arthritis (RA) rabbits, and to reveal the analgesic central mechanism of buccal acupuncture, thereby providing a theoretical basis for the treatment of pain by buccal acupuncture.

Methods

Forty rabbits were randomly divided into a normal group, a model group, a body acupuncture group, and a buccal acupuncture group, with 10 rabbits in each group. No model was established in the normal group, while equal dose of normal saline was injected at the matched site and time point; rabbits in other groups were subjected to the establishment of RA models using egg protein. From the 27th day of the experiment, rabbits in each group received the designated intervention. Rabbits in the normal group and the model group were fixed for 30 min every day using the same method as those in the other groups. In the acupuncture group, Dubi (ST 35) and Zusanli (ST 36) on bilateral hind limbs were selected. Perpendicular needling (using the needles with 0.25 mm in diameter and 25 mm in length) was performed with twirling manipulation for 15 s at intervals of 5 min. The needles were retained for 30 min and acupuncture was performed once a day. In the buccal acupuncture group, the knee point in the buccal acupuncture and needles with a diameter of 0.25 mm and a length of 15 mm were selected. Oblique needling was performed with twirling manipulation for 15 s at intervals of 5 min. The needles were retained for 30 min and acupuncture was performed once a day. The thermal pain thresholds at the 0, 5, 15, 30, 60, 120 and 240 min after the 1st and 10th acupuncture therapy were measured with a PL-200 thermal-inducing pain meter. After the 10th acupuncture therapy, rabbit’s hypothalamus was removed, and the 5-HT and NE concentrations in the hypothalamus at the peak point of the acupuncture pain threshold curve were determined by high performance liquid chromatography (HPLC).

Results

The analgesic effect was obvious at 5 min after buccal acupuncture started, peaked at 30 min, and decreased to the lowest value at 240 min. Rabbits in the body acupuncture group began to show significant analgesic effect at 15 min, which was peaked at 30 min, and began to decline at 60 min. The pain threshold at 240 min was still higher than that at 0 min. Compared with the model group, the concentrations of hypothalamic 5-HT in the buccal acupuncture group and the body acupuncture group was significantly increased, and the between-group differences were statistically significant (both P<0.05). The NE/5-HT ratios in hypothalamus in the buccal acupuncture group and the body acupuncture group were significantly lower than the ratio in the model group, and the differences were statistically significant (both P<0.05); difference in the decrease was statistically significant between the buccal acupuncture group and the body acupuncture group (P<0.05).

Conclusion

The analgesic effect of buccal acupuncture shows an obvious time-dependent curve. It is characterized by rapid onset of pain relief, rapid increase and decline in pain threshold. 5-HT and NE levels in rabbit’s hypothalamus can be affected by buccal acupuncture, with increased 5-HT concentration and reduced NE/5-HT ratio.

摘要

目的

观察颊针对类风湿性关节炎(RA)兔镇痛效应的时效特点, 以及兔下丘脑中5-羟色胺(5-HT)和去甲肾上腺素(NE)含量的变化, 以揭示颊针镇痛的中枢机制, 从而为颊针治疗疼痛提供理论依据。

方法

将40只大耳白兔随机分成正常组、模型组、体针组和颊针组, 每组10只。正常组不造模, 但在相应部位、时间注射等剂量生理盐水; 其余组复制应用卵蛋白诱导的家兔关节炎模型。从实验第27天开始, 各组分别接受相应干预。正常组每天用与其他组相同方法固定30 min。模型组每天用与其他组相同的方法固定 30 min。体针组选双侧后肢犊鼻和足三里, 用直径0.25 mm, 长25 mm的毫针直刺, 每隔5 min捻转行针15 s, 留针30 min, 每天针刺1次。颊针组选颊针中的膝穴, 用直径0.25 mm, 长15 mm的毫针斜刺。每隔5 min捻转行针15 s, 留针30 min, 每天针刺1次。各组连续干预10 d。在治疗第1次和第10次针刺时用PL-200热刺痛仪测定针刺后0、5、15、30、60、120、240 min热痛阈值。治疗10次后, 取出兔下丘脑, 采用高效液相色谱荧光检测法测定下丘脑针刺痛阈曲线峰值点时的5-HT和NE含量。

结果

颊针针刺5 min时产生明显镇痛效应, 30 min时达到峰值, 240 min时降到最低值。体针组针刺15 min时开始显示明显镇痛效应, 30 min时到达峰值, 60 min时镇痛效应明显开始下降, 240 min时痛阈值仍高于0 min时的痛阈值。与模型组比较, 颊针组和体针组下丘脑中5-HT含量均显著升高, 组间差异均有统计学意义(均P<0.05), 颊针组和体针组下丘脑的NE/5-HT比值均低于模型组, 组间差异均有统计学意义(均P<0.05); 颊针组下降情况与体针组有统计学差异(P<0.05)。

结论

颊针镇痛效应具有明显的时间变化曲线, 表现为镇痛起效快、痛阈值上升快, 下降亦快; 颊针对兔下丘脑中的5-HT和NE含量均有影响, 可以使5-HT含量升高, 使NE/5-HT比值降低。