明胶酶调制吗啡耐受与依赖形成的脊髓机制研究

The mechanisms of morphine tolerance and dependence remain elusive and continue to be the difficult issue of research. It is of clinical importance to find the specific mechanisms underlying opioid actions and develop medications to facilitate morphine utility. Gelatinase (MMP-2/9) are zinc dependent endopeptidases and can be detected in neuron and glia. Gelatinase can regulate diverse biological processes through cleavage of cytokines, cell surface receptors and extracellular proteins. The applicant has found that inhibition of spinal MMP-9 can suppresses neuron excitability, upregulation of molecular markers related to synaptic plasticity and the behavioral signs of naloxone-precipitated morphine withdrawal. Analgesic effects of morphine could also be rescued by inhibiting spinal MMP-9 or MMP-2. Those findings suggest that MMP-2/9 may play an important role in morphine tolerance and dependence. However, because MMP-2/9 widely express in CNS and play an important role in many physiological processes, there may be many bad side effects if they are taken as the therapeutic targets directly. Thus, we need to further investigate the roles of gelatinase in morphine dependence and tolerance, and find the new effective targets.We will use the behavior, western blotting, immunohistochemistry methods to investigate how gelatinase work in morphine tolerance and withdrawal models. The research is useful for finding the mechanism underlying morphine tolerance and dependence and suggests that inhibition of gelatinase signaling may be of potential clinical benefit in preventing, minimizing, or reversing morphine-induced side effects, thereby facilitating the clinical utility of opioid drugs.

吗啡类药物的耐受性和成瘾性问题的发生机制一直是科研热点与难点，深入研究其发生机制并寻找新的干预靶点，提高吗啡的药效并减少副作用是迫切任务。明胶酶（MMP-2/9）是依赖于锌离子的内切蛋白水解酶，可通过裂解活化多种炎症因子、膜表面蛋白和细胞外蛋白，调控多种细胞功能与细胞间通信。申请者最新的研究首次表明：抑制脊髓水平MMP-9可有效抑制吗啡造成的脊髓中枢敏化和胶质细胞活化，显著缓解吗啡戒断的躯体症状，并增强吗啡镇痛效能。但是MMP-2/9在体内广泛存在，把其作为药物干预的直接靶点，副作用较大。深入研究明胶酶参与吗啡耐受和依赖形成的详细分子机制，可能找到新的药物干预靶点。本项目拟利用吗啡耐受和躯体依赖行为学模型，结合细胞和分子水平研究，阐明MMP-2/9调控脊髓不同细胞功能及细胞间通讯的详细分子机制。研究成果不仅有助于揭示吗啡耐受和依赖的形成机制，也为临床治疗提供新策略，为药物研发提供新靶标。

本课题围绕着初级感觉神经元以及脊髓背角的明胶酶即MMP-2/9在吗啡成瘾与耐受过程中的作用及分子机制开展研究。.研究目标是：阐明明胶酶在吗啡成瘾与耐受过程中的变化规律以及作用机制。.本研究具有以下发现：1. 阐明了MMP-9对吗啡躯体依赖性与耐受进程的关键性作用。2.证明了抑制了MMP-2对吗啡镇痛作用的急慢性耐受没有显著改善作用。3.利用基因敲除鼠和脊髓在体电生理模型，阐明了MMP-9对吗啡造模以及高频电刺激导致引起的异常兴奋性和突触可塑性变化有显著影响，并揭示了下游分子机制。我们的研究数据最终证明脊髓背角的MMP-9对吗啡处理导致的突触可塑性变化具有关键性影响，其作用机制是通过MMP-9- intergrinβ1- NMDA- CaMKII– CREB 级联通路而实现的，同时揭示抑制小胶质细胞中的TRL-4-NF-kB-MMP-9信号通路具有良好的镇痛以及抑制吗啡耐受作用。这些发现为吗啡成瘾与耐受这一临床重大问题的解决提供了新的思路。.本课题研究已投稿并接收三篇SCI文章，影响因子分别为5.8,3.2和3.2.，另有两篇SCI文章准备投稿，培养1名博士生和3名研究生毕业。对照课题计划书，已超额完成研究任务。