Analgesic effect and related mechanism of peripheral acupoints electroacupuncture on superficial partial-thickness burn rats
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摘要: 目的 观察外周穴位电针对浅Ⅱ度烧伤大鼠早期的镇痛效果并且探讨相关机制。 方法 将80只SD大鼠按随机数字表法分为假伤组、单纯烧伤组、电针组、假电针组,每组20只。假伤组大鼠右后足模拟致伤,余3组大鼠右后足建立浅Ⅱ度烫伤(下称烧伤)模型。伤后12 h开始,对电针组和假电针组大鼠右后足分别进行相当于人体解剖部位的"足三里"和"三阴交"外周穴位电针和模拟电针治疗,每天1次,每次治疗30 min,连续治疗3 d。每组取5只大鼠,于伤前及伤后12、24、36、48、60、72 h进行机械痛阈值检测;每组另取5只大鼠,于前述时相点进行热痛阈值检测。伤后48 h,各组取5只大鼠脑组织,进行免疫组织化学染色,观察中脑导水管周围灰质(PAG)区域胶质纤维酸性蛋白(GFAP)表达阳性的星形胶质细胞形态及分布并计数;同时取每组余下5只大鼠脑组织,进行蛋白质印迹法检测PAG区域星形胶质细胞中GFAP表达。对数据行重复测量方差分析、单因素方差分析和SNK检验。 结果 (1)与假伤组比较,单纯烧伤组和假电针组大鼠伤前及伤后12 h机械痛阈值无明显变化(
P 值均大于0.05),伤后24~72 h机械痛阈值显著降低(P 值均小于0.05);电针组大鼠伤后36~72 h机械痛阈值显著降低(P 值均小于0.05)。电针组大鼠伤后24 h机械痛阈值较单纯烧伤组和假电针组均显著升高(P 值均小于0.05)。(2)与假伤组比较,单纯烧伤组和假电针组大鼠伤前热痛阈值无明显变化(P 值均大于0.05),伤后12~72 h热痛阈值显著降低(P 值均小于0.05);电针组大鼠伤后12~60 h热痛阈值显著降低(P 值均小于0.05)。电针组大鼠伤后24~48 h热痛阈值较单纯烧伤组和假电针组均显著升高(P 值均小于0.05)。(3)假伤组大鼠PAG区域GFAP表达阳性的星形胶质细胞分布弥散,细胞体积较小,胞体不明显,发出的突起稀疏、纤细且短。单纯烧伤组大鼠PAG区域GFAP表达阳性的星形胶质细胞分布相对集中,胞体肥大、肿胀,突起增多且较长。假电针组、电针组大鼠PAG区域GFAP表达阳性的星形胶质细胞形态及分布与单纯烧伤组相似。假伤组、单纯烧伤组、电针组、假电针组大鼠PAG区域GFAP表达阳性的星形胶质细胞数分别为(44±4)、(39±4)、(27±4)、(36±5)个,单纯烧伤组大鼠PAG区域GFAP表达阳性的星形胶质细胞数较假伤组显著减少(P <0.05),与假电针组相近(P >0.05)。电针组大鼠PAG区域GFAP表达阳性的星形胶质细胞数显著少于单纯烧伤组和假电针组(P 值均小于0.05)。(4)假伤组、单纯烧伤组、电针组、假电针组大鼠PAG区域星形胶质细胞中GFAP表达量分别为1.11±0.16、0.66±0.15、0.34±0.06、0.56±0.09,单纯烧伤组大鼠PAG区域星形胶质细胞中GFAP表达量显著低于假伤组(P <0.05),与假电针组相近(P >0.05)。电针组大鼠PAG区域星形胶质细胞中GFAP表达量显著低于单纯烧伤组和假电针组(P 值均小于0.05)。 结论 外周穴位电针可缓解大鼠浅Ⅱ度烧伤早期伴随的疼痛,其可能的机制为减少PAG区域星形胶质细胞的活化。Abstract: Objective To observe the analgesic effect and related mechanism of peripheral acupoints electroacupuncture on superficial partial-thickness burn rats. Methods Eighty SD rats were divided into sham injury group (SI), pure burn group (PB), electroacupuncture group (E), and sham electroacupuncture group (SE) according to the random number table, with 20 rats in each group. Right posterior leg of rats in group SI were sham injured, while superficial partial-thickness scald (hereinafter referred to as burn) model was reproduced on the right posterior leg of rats in the latter three groups. Electroacupuncture of peripheral acupoints of right posterior leg of rats (equivalent to Zusanli point and Sanyinjiao point of human) in group E were performed from post injury hour (PIH) 12 on, while rats in group SE were treated with sham electroacupuncture, with 30 min each time, one time a day for 3 days. Before injury and at PIH 12, 24, 36, 48, 60, and 72, the threshold of mechanical pain of 5 rats in each group was tested, and the threshold of heat pain of another 5 rats in each group was tested. At PIH 48, brain tissue of 5 rats in each group was obtained to observe the morphology and distribution of astrocytes with positive expression of glia fibrillary acidic protein (GFAP) in periaqueductal gray (PAG) area by immunohistochemical staining, and the number of astrocytes was calculated. At the same time, brain tissue of the rest 5 rats in each group was obtained to determine the expression of GFAP of astrocytes in PAG area with Western blotting. Data were possessed with analysis of variance of repeated measurement, one-way analysis of variance, and SNK test. Results (1) Compared with that in group SI, the threshold of mechanical pain of rats in groups PB and SE had no significant change before injury and at PIH 12 (withP values above 0.05), but was significantly decreased from PIH 24 to 72 (withP values below 0.05); while the threshold of mechanical pain of rats in group E was significantly decreased from PIH 36 to 72 (withP values below 0.05). The threshold of mechanical pain of rats in group E was significantly higher than that in groups PB and SE at PIH 24 (withP values below 0.05). (2) Compared with that in group SI, the threshold of heat pain of rats in groups PB and SE had no significant change before injury (withP values above 0.05), but was significantly decreased from PIH 12 to 72 (withP values below 0.05); while the threshold of heat pain of rats in group E was significantly decreased from PIH 12 to 60 (withP values below 0.05). The threshold of heat pain of rats in group E was significantly higher than that in groups PB and SE from PIH 24 to 48 (withP values below 0.05). (3) The distribution of astrocytes with positive expression of GFAP in PAG area of rats in group SI was diffuse. The cell volume was small with cell body unobvious, and the projections were sparse, fine and short. The distribution of astrocytes with positive expression of GFAP in PAG area of rats in group PB was relatively concentrated. The cell body was hypertrophy and swelling, and the projections were increased and extended. The morphology and distribution of astrocytes with positive expression of GFAP in PAG area of rats in groups SE and E was similar to that in group PB. The numbers of astrocytes with positive expression of GFAP in PAG area of rats in groups SI, PB, E, and SE were 44±4, 39±4, 27±4, and 36±5, respectively. The number of astrocytes with positive expression of GFAP in PAG area of rats in group PB was significantly less than that in group SI (P <0.05), but similar to that in group SE (P >0.05). The number of astrocytes with positive expression of GFAP in PAG area of rats in group E was significantly less than that in groups PB and SE (withP values below 0.05). (4) The expressions of GFAP of astrocytes in PAG area of rats in groups SI, PB, E, and SE were 1.11±0.16, 0.66±0.15, 0.34±0.06, and 0.56±0.09, respectively. The expression of GFAP of astrocytes in PAG area of rats in group PB was significantly lower than that in group SI (P <0.05), but similar to that in group SE (P >0.05). The expression of GFAP of astrocytes in PAG area of rats in group E was significantly lower than that in groups PB and SE (withP values below 0.05). Conclusions Electroacupuncture of peripheral acupoints can release the pain followed superficial partial-thickness burn in rats at early stage, and the possible mechanism is that it reduces the activation of astrocytes in PAG area.-
Key words:
- Burns /
- Electroacupuncture /
- Periaqueductal gray /
- Astrocytes
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