电针对慢性炎性痛大鼠中枢不同脑区GABA_A受体mRNA表达的干预研究

目的:观察中枢不同脑区γ-氨基丁酸A型(GABA_A)受体mRNA在慢性炎性痛大鼠的脑内表达及电针的干预作用。方法:48只SPF级雄性SD大鼠随机分为空白对照组、模型对照组、电针组和假电针组,每组12只。采用足底注射弗氏完全佐剂建立慢性炎性痛模型,电针组于造模后28 d介入电针治疗,取"后三里"和"昆仑"穴,予疏密波、频率2 Hz/100 Hz、强度0.5~1.5 mA,治疗30 min,仅干预1次。假电针组与电针组取穴相同,仅刺入皮下,连接电针,不通电,固定30 min。观察各组大鼠造模前,造模后1、3、7、14、21、28 d机械痛阈、热痛阈变化及造模后29 d情绪行为变化,前扣带皮层、杏仁核、下丘脑GABA_A受体mRNA相对表达量。结果:造模后1、3、7、14、21、28 d各个时间点与空白对照组比较,模型对照组大鼠机械痛阈变化率和热痛阈变化率显著降低(均P<0.01);造模后29 d,模型对照组大鼠旷场实验中央区域运动距离和中央区域停留时间较空白对照组明显减少(均P<0.05)。干预后与模型对照组、假电针组比较,电针组能显著增加机械痛阈变化率、热痛阈变化率、中央区域运动距离、中央区域停留时间(P<0.01,P<0.05)。造模后29 d各组大鼠前扣带皮层、下丘脑GABA_A受体mRNA表达差异无统计学意义(P>0.05);与空白对照组比较,模型对照组大鼠杏仁核GABA_A受体mRNA表达显著降低(P<0.01),电针组干预后大鼠杏仁核GABA_A受体mRNA表达较模型对照组、假电针组增多(P<0.01)。结论:单次电针可显著提高慢性炎性痛大鼠机械痛阈和热痛阈,改善情绪异常行为,其机制可能与提高杏仁核GABA_A受体mRNA表达相关。

Effect of electroacupuncture on expression of GABA_A receptor mRNA in different brain regions in rats with chronic inflammatory pain

Objective To observe the expression of GABA_A receptor mRNA in different brain regions of the central nervous system in chronic inflammatory pain rats and the intervention effect of electroacupuncture(EA). Methods A total of 48 SPF male SD rats were randomly divided into a blank control group, a model control group, an EA group and a sham EA group, 12 rats in each group. The model of chronic inflammatory pain was established by injecting Freund’s complete adjuvant into the foot. The EA group was treated with EA 28 days after the model establishment. The "Housanli"(ST 36) and "Kunlun"(BL 60) were selected and treated with dilatational wave, 2 Hz/100 Hz in frequency, 0.5-1.5 mA for 30 min;EA was given only once. In the sham EA group, the same acupoints were selected but the needles were only inserted into subcutaneous area;EA was connected for 30 min without electrical stimulation. The behavior changes of mechanical pain threshold and thermal pain threshold before model establishment, 1 day, 3 days, 7 days, 14 days, 21 days and 28 days after the model establishment as well as emotional behavior 29 days after the model establishment were observed;the relative expressions of GABA_A receptor mRNA in anterior cingulate cortex, amygdala and hypothalamus were observed. Results Compared with the blank control group, the change rates of mechanical pain threshold and thermal pain threshold in the model control group were decreased significantly 1 day, 3 days, 7 days, 14 days, 21 days, 28 days after model establishment(P<0.01);29 days after model establishment, the movement distance and staying time in the central area of open field test in the model control group were decreased significantly(P<0.05). After EA intervention,compared with the model control group and the sham EA group, the change rates of mechanical pain threshold and thermal pain threshold, as well as the movement distance and the staying time of central area were significantly increased in the EA group(P<0.01, P<0.05). Twenty-nine days after model establishment, the expression of GABA_A receptor mRNA in anterior cingulate cortex and hypothalamus was not significantly different among all groups(P>0.05). Compared with the blank control group, the expression of GABA_A receptor mRNA in the amygdala was decreased significantly in the model control group(P<0.01);compared with the model control group and the sham EA group, the expression of GABA_A receptor mRNA in amygdala was increased after intervention in the EA group(P<0.01). Conclusion Single treatment of EA could significantly increase the mechanical pain threshold and thermal pain threshold, improve abnormal emotional behavior in rats with chronic inflammatory pain, which may be related to the increasing of expression of GABA_A receptor mRNA in the amygdala.