vlPAG中GABA能神经元参与电针缓解IBS小鼠内脏痛的机制研究

GABAergic neurons in vlPAG downregulates visceral hypersensitivity by electroacupuncture in IBS mice

关键词:  电针  光遗传  腹外侧中脑导水管周围灰质  γ-氨基丁酸  肠易激综合征  内脏痛

Key words:  electroacupuncture  optogenetics  vlPAG  GABA  irritable bowel syndrome  visceral pain

摘要:

[目的] 以肠易激综合征（IBS）小鼠模型为例，采用光遗传技术调控腹外侧中脑导水管周围灰质（vlPAG）中的γ-氨基丁酸（GABA）能神经元，探讨vlPAG中GABA能神经元参与电针缓解IBS小鼠内脏痛的机制。[方法] 将Vgat-Cre小鼠随机分为：1）正常组，给予与电针组相同固定。2）模型组，给予与电针组相同固定。3）模型+eNpHR组，注射rAAV2/9-EF1α-DIO-eNpHR3.0-EGFP病毒，给予黄光刺激（20 Hz，5 ms，4 mW）。4）模型+ChR2组，注射rAAV2/9-EF1α-DIO-hChR2-EGFP病毒，给予蓝光刺激（20 Hz，5 ms，4 mW）。5）电针组，取双侧“足三里”穴，疏密波，频率2/100 Hz，电流1 mA，每次30 min，每日1次，连续治疗7 d。采用2，4，6-三硝基苯磺酸（TNBS）灌肠法制备IBS慢性内脏痛模型；通过一般情况观察、腹壁撤回反射（AWR）评分确认模型制备成功后，利用光遗传技术对vlPAG的GABA能神经元进行激活和抑制调控，分析各组小鼠的AWR评分变化。[结果] 1）与正常组比较（干预前），模型组小鼠AWR评分上升（P＜0.01）。2）与给光前比较，模型+eNpHR组小鼠在给予黄光抑制GABA能神经元时，AWR评分上升（P＜0.05）；模型+ChR2组小鼠在给予蓝光激活GABA能神经元时，AWR评分下降（P＜0.05）。3）与正常组比较（干预后），模型组小鼠AWR评分上升（P＜0.01）；与模型组比较，模型+eNpHR组AWR评分上升（P＜0.05）；模型+ChR2组AWR评分下降（P＜0.05）；电针组AWR评分下降（P＜0.05）。[结论] 光遗传技术能够有效调控vlPAG脑区中的GABA能神经元，而电针对IBS小鼠的疼痛行为学影响与光遗传激活GABA能神经元产生的效应趋势一致，说明电针可能通过激活vlPAG中的GABA能神经元发挥缓解IBS小鼠内脏痛的作用。

Abstract:

[Objective] Taking the mouse model of irritable bowel syndrome(IBS) as an example,optogenetic technology was used to regulate GABAergic neurons in ventrolateral periaqueductal gray(vlPAG),and the mechanism of GABAergic neurons in vlPAG participating in electroacupuncture to relieve visceral pain in IBS mice was discussed. [Methods] Vgat-Cre mice were randomly divided into:1) normal group(N):no treatment was given,only the same fixation as the electroacupuncture group was given;2) model group (M):do not do any treatment,only give the same fixation as the electroacupuncture group;3) model+eNpHR group(M+eNpHR):injection of rAAV2/9-EF1α-DIO-eNpHR3.0-EGFP virus,yellow light stimulation (20 Hz,5 ms,4 mW);4) model+ChR2 group (M+ChR2):injection of rAAV2/9-EF1α-DIO-hChR2-EGFP virus,blue light stimulation(20 Hz,5 ms,4 mW);5) electroacupuncture group(EA):acupuncture:(double),dense wave,frequency 2/100 Hz,current 1 mA,30 min/time,once a day,continuous treatment for 7 d. A model of chronic visceral pain of IBS was prepared by enema with 2,4,6-trinitrobenzen sulfunic acid. After the model was successfully prepared by general observation and abdominal wall withdrawal reflex score,the GABAergic neurons of vlPAG were activated or inhibited by optogenetic technology,and the changes of AWR scores in each group of mice were analyzed. [Results] 1)Compared with the normal group,the AWR score of mice in the model group increased(P<0.01);2) compared with before giving light,the AWR score of mice in the model+eNpHR group increased(P<0.05) when given yellow light to inhibit GABAergic neurons;the model+ChR2 group decreased when blue light activated GABAergic neurons (P<0.05);3) compared with the normal group, the AWR score of mice in the model group increased(P<0.01),and compared with the model group,the AWR score of the model+eNpHR group increased(P<0.05). The AWR score of the model+ChR2 group decreased(P<0.05). The AWR score decreased in the electroacupuncture group(P<0.05). [Conclusion] Optogenetic technology can effectively regulate GABAergic neurons in vlPAG brain regions,and the pain behavior effect of electricity on IBS mice is consistent with the effect trend of optogenetic activation of GABAergic neurons,indicating that electroacupuncture may play a role in alleviating visceral pain in IBS mice by activating GABAergic neurons in vlPAG.