外侧缰核内谷氨酸能神经元参与慢性痛和抑郁调控的机制研究

Chronic pain usually accompanied by anxiety, depression and other emotional disorders, while the latter will further aggravate the pain again. The combination of research for chronic pain and depression, however, is very scarce at present study. The habenular nucleus is a relay station of the limbic system and the brain stem. Recent research has confirmed the lateral subnucleus, lateral habenular nucleus ( LHb), plays an vital role in both functional regulation of pain and depression. Our preliminary experiment results also observed the large numbe of vesicular glutamate transporter 2 (VGLUT2)-positive neurons in LHb. Optogenetic technology was applied to specific activating VGLUT2-positive fibers in midbrain ventral tegmental area (VTA) from the LHb in VGLTU2-Cre mouse with neuropathic pain, and further depressive behavior were detected in mice. After damage to the nucleus, the above symptoms were improved significantly. These results imply that glutamatergic neurons in LHb involved in the regulation of chronic pain induced depression. To certify this hypothesis, the project plans will constitute chronic pain induced depression animal model, and investigate the function and the expression change of glutamatergic neurons (VGLUT2 and βCaMKII) involved in regulating chronic pain and depression in LHb by integrated use of technologies including behavior, optogenetics, morphology, electrophysiologyl and molecular biology. The relative intracellular signaling molecules also are detected, and by evaluating the effect of inhibition of VGLUT2 expression in LHb on the above changes. Further probe the a key role of glutamatergic neurons in LHb in regulation of chronic pain induced depression behavior and the possible molecular mechanism. Our proposed study may provide a novel strategies and targets for the drug research and development clinically in prevention and control of chronic pain and depression.

慢性痛多伴有焦虑、抑郁等情绪障碍，而后者又会进一步加重疼痛。然而将二者结合进行研究却十分匮乏。缰核是边缘系统与脑干联络的中继站，新近研究证实其外侧亚核，即外侧缰核（LHb）同时参与了疼痛与抑郁的功能调控。我们的预实验观察到LHb内存在大量的囊泡膜谷氨酸转运体2（VGLUT2）神经元，特异性激活LHb向中脑腹侧被盖区（VTA）投射纤维内的VGLUT2后，小鼠的抑郁行为进一步加重；毁损该核团后上述症状明显改善。提示其内谷氨酸能神经元参与了慢性痛诱导抑郁的调控过程。为了证实此假设，本项目拟构建慢性痛诱导抑郁动物模型，综合运用行为学、光遗传学、形态学、电生理和分子生物学等技术检测LHb内谷氨酸能神经元参与调控慢性痛和抑郁的功能和表达变化、相关的细胞内信号分子；抑制其表达对上述变化的影响；明确LHb内谷氨酸能神经元在慢性痛诱导抑郁调控中的关键作用，为临床上慢性痛及其抑郁的防治药物的研发提供新的靶点。

慢性痛多伴有焦虑、抑郁等情绪障碍，而后者又会进一步加重疼痛。然而将二者结合进行研究却十分匮乏。近年来，外侧缰核（LHb) 和中脑腹侧被盖区（VTA）因其同时在疼痛和抑郁中发挥作用而引起广泛关注。本研究通过构建慢性痛诱导抑郁动物模型，综合运用行为学、光遗传学、药理遗传学、形态学、电生理和分子生物学等技术检测了LHb内谷氨酸能神经元参与调控慢性痛和抑郁的功能变化。结果显示：（1）LHb向VTA有大量的纤维投射，即可直接投射至VTA内DA能神经元，也可直接投射至GABA能神经元，且这两条通路均可被外周疼痛刺激所激活。（2）长期慢性痛可以诱发部分小鼠出现抑郁样行为，并导致模型小鼠LHb内β-CaMKII表达增加。慢性痛发生后LHb-VTA投射神经元和VTA内GABA能神经元的自发放电活动增加，使VTA内DA能神经元受到抑制性传入增多，导致VTA内DA能神经元的活动受到抑制，TH的表达下调。其中慢性痛诱发的LHb神经元的过度活化以及由此引发的对VTA内DA能神经元功能的降低可能与慢性痛诱发抑郁密切相关。（3） LHb-VTA通路可参与对慢性痛模型小鼠的痛行为和抑郁样行为的调控，而其中VTA内GABA能神经元的活化可能发挥更关键的作用。（4）LHb投射纤维与VTA内DA能神经元之间既有单突触连接，亦可通过局部GABA能神经元的中继后再间接投射至DA能神经元；而慢性痛诱导抑郁发生后LHb-VTA投射通路会发生突触可塑性改变，这种改变既有突触前机制的参与，亦有突触后机制的作用。在体利用光诱发LTP的方式也进一步证实，该通路可塑性改变可能是慢性痛诱发抑郁发生的关键。本研究为临床上慢性痛及其抑郁的防治药物的研发提供l了新的靶点。. 本研究工作的主要内容目前已经整理成一篇大论文，有望在近期内将该论文投出，将在 IF >10 的国际杂志上发表。另外，用该基金号（第一标注9篇，第二标注2篇）共发表论文11篇，其中SCI论文7篇（累计影响因子：40.935），中文核心期刊论文4篇。该部分研究成果参加国内大学生课外学术科研比赛分别获特等奖1项，一等奖2项。