伏隔核胆碱能神经元在片段睡眠剥夺引发抑郁行为中的作用研究

The neural mechanisms of sleep disorders and major depressive disorder is the hotspot and difficulty which related to multiple sites in neural pathways. The nucleus accumbens (NAC), a structure involved in natural reward-related behaviors and responses to drugs such as cocaine which has been identified as a critical site in the neuronal circuits controlling reward responses, motivation and mood. There has been evidence showed that NAC is associated with sleep and depression whereas the cellular mechanism and the circuits of the regulating role of NAC on these diseases are not fully clear. Based on our results of in vitro brain slice electrophysiological experiments which found that chronic sleep fragmentation led to the firing pattern of cholinergic interneurons in NAC showed irregular, changeable and the firing frequency increased significantly, we focus on cholinergic interneurons in NAC to study the electrophysiological characteristics and behavior change of chronic sleep fragmentation causes depression model mice by using in vitro brain slice patchclamp technique and pharmacogenetics ( DREADDs) method. Our aims are to clarify the key role of cholinergic interneurons in NAC in the sleep disorders and depression by changing the activity of cholinergic interneurons to regulate depressive symptoms caused by sleep fragmentation and to provide direct experimental data and comprehensive theoretical explanation for finding the key target to cure related diseases as well as to reveal the neurobiological mechanisms of depression caused by sleep fragmentation.

睡眠障碍以及由此引发的抑郁症状的相关神经机理的研究是目前的热点和难点，涉及到神经通路中的多个位点。其中，伏隔核是中枢神经回路中一个极其重要的核团，是药物成瘾的关键部位，同时参与动机、情感和奖赏效应的整合和表达。已有研究表明伏隔核与睡眠和抑郁情绪有关，但是对于伏隔核调控这些疾病在细胞层面及神经回路方面的机理尚不完全清楚。基于我们在体外脑片电生理实验中发现长期片段睡眠导致伏隔核胆碱能神经元的放电模式呈现了不规律、多变化、自发放频率显著升高的特点，本项目以伏隔核中的胆碱能神经元为主要的研究切入点，通过使用离体脑片膜片钳技术和遗传药理学方法（DREADDs技术），对片段睡眠剥夺引发抑郁症状模型小鼠的伏隔核胆碱能神经元的电生理特性变化和行为学改变进行研究，通过改变胆碱能神经元的活性来调控由片段睡眠剥夺引发的抑郁症状的产生，阐明伏隔核胆碱能神经元在睡眠障碍以及抑郁症中的关键作用.

本项目的研究目标是探究大脑伏隔核胆碱能神经元在睡眠障碍以及抑郁症中的关键作用，我们采用跑台实验（Treadmill running）模拟长期片段睡眠剥夺，采用离体脑片膜片钳技术对成功建模的ChAT-EGFP小鼠大脑伏隔核胆碱能神经元的电生理特性进行测定，并利用遗传药理学方法（DREADDs）来抑制模型小鼠大脑伏隔核胆碱能神经元的兴奋性来研究动物行为的改变。结果显示片段睡眠剥夺使成功建模的ChAT-EGFP小鼠大脑伏隔核胆碱能神经元的膜兴奋性呈现显著下降、神经元的自发动作电位显著增加的变化趋势，而CNO使注射有AAV-DREADDs-Gi病毒的ChAT-cre小鼠大脑伏隔核胆碱能神经元的自发放频率显著降低，说明抑制了ChAT神经元的兴奋性；动物行为学实验显示，抑制胆碱能神经元兴奋性可以逆转长期睡眠剥夺小鼠自主获取糖丸数量的行为。这些结果表明通过改变胆碱能神经元的兴奋性可以调控由长期片段睡眠剥夺引发的抑郁症状的产生，这对于进一步阐明伏隔核胆碱能神经元在睡眠障碍以及抑郁症中的关键作用提供了新的实验数据和更深入全面的理论阐释。