小鼠前扣带回皮质γ-氨基丁酸能神经元调控慢性痒觉

GABAergic neurons in ACC region of mice modulate chronic itch

目的:研究位于小鼠前扣带回皮质(ACC)的γ-氨基丁酸(GABA)能神经元对痒觉的调控作用。方法:选取24只6周龄GAD2-Cre小鼠随机分为对照组、病毒激活组和病毒抑制组。采用脑立体定位注射方法向小鼠ACC脑区注射重组腺相关病毒(AAV)病毒。通过给予各种致痒剂建立急性痒觉与慢性痒觉模型,观察调控小鼠ACC脑区GABA能神经元对不同类型的痒觉模型的影响;使用免疫荧光与电生理记录方法观察慢性痒小鼠ACC脑区GABA能神经元的激活率及电生理学特征;采用化学遗传学方法,观察调控ACC脑区GABA能神经元对痛觉行为的影响。结果:激活和抑制小鼠ACC脑区的GABA能神经元,对组胺性痒(P> 0.05)和非组胺性痒(P> 0.05)没有调控作用。抑制ACC脑区的GABA能神经元,能够显著抑制慢性痒引起的抓挠反应(P <0.05)。慢性痒模型ACC脑区的GABA能神经元激活增加(P <0.05),同时兴奋性增高(P <0.05)。激活和抑制ACC脑区的GABA能神经元对痛觉没有明显影响(P> 0.05)。结论:位于小鼠ACC脑区的GABA能神经元能够特异性调控慢性痒行为,同时,在慢性痒条件下ACC脑区的GABA能神经元兴奋性增加。ACC脑区GABA能神经元对痛觉没有影响。

Objective:To investigate the modulation of GABAergic neurons in mice anterior cingulate cortex(ACC)on itch transmission.Methods:Twenty-four six-week-old GAD2-Cre mice were divided randomly into control group,viral activation group and viral inhibition group.Recombinant adeno-associated virus(AAV)were injected into mice ACC region by stereotaxic methods.Acute and chronic itch models were established by applying diverse pruritogens and influence on the different itch models by modulating GABAergic neurons in the ACC was observed.Immunofluorescence and electrophysiological recording were performed to observe activation ratio and electrophysiological properties of ACC GABAergic neurons in mice with chronic itch.Chemogenetic method was used to observe the effects on pain behaviors by regulating ACC GABAergic neurons.Results:Activation and inhibition of GABAergic neurons in the ACC have no effects on histaminergic(P>0.05)and nonhistaminergic itch(P>0.05)in mice.Inhibition of GABAergic neurons in the ACC significantly suppressed scratches induced by chronic itch(P<0.05).GABAergic neurons in the ACC of chronic itch mice were abundantly activated(P<0.05)and displayed hyperexcitability(P<0.05).Activation and inhibition of GABAergic neurons in the ACC didn't have a significant influence on pain(P>0.05).Conclusion:GABAergic neurons in mice ACC can specifically modulate chronic itch and simultaneously gain hyperexcitability under chronic itch conditions.GABAergic neurons in the ACC have no effects on pain.