最新研究揭示尿苷是一种重要的神经调质，参与成瘾药物中枢作用的调节。我们发现吗啡通过μ受体诱导中枢释放尿苷，提示尿苷也参与吗啡成瘾的调节。已知，尿苷水平受相关代谢酶和转运体共同调节，然而尿苷对吗啡成瘾的调控，尤其是尿苷代谢酶与转运体在此过程中的机制还未有报道。本项目采用在体脑微透析、RT-PCR、western blot 等手段，从神经化学、神经行为学和分子生物学等多水平：1.考察吗啡引起中枢尿苷释放的作用规律与机制；2.研究外源性尿苷及代谢产物对吗啡成瘾的调节作用；3.探索尿苷代谢酶胞外5'核苷酸酶(5-NT)与平衡型核苷转运体(ENT)对吗啡依赖的调控机制。本项目创新性地研究成瘾性药物-吗啡对神经调质-尿苷的相互关系，将完善吗啡成瘾的机制，明晰尿苷作为神经调质在吗啡成瘾中的调控作用，同时揭示尿苷代谢酶与转运体在吗啡成瘾中的分子机制，为进一步围绕相关靶点开发新型抗阿片成瘾药物奠定理论基础。

Recently, uridine, a neuromodulator in the central nervous system (CNS), has been proposed to participate in drug addiction. Our previous study has shown that acute morphine induced a significant uridine release in the CNS via opioid receptor, suggesting uridine in the CNS may also be involved in opioid-addiction. Extracellular uridine level can be modulated either by uridine metabolism enzyme ecto-5'-nucleotidase (5-NT) or by equilibrative nucleoside transporters (ENT). However, the mechanism and the pathological implication of morphine-induced uridine release are not yet well understood. Thus, the present project investigates: 1. the characteristic and mechanisms of morphine-induced uridine release; 2. the effect of uridine and its metabolites on morphine-induced behavioral and neurochemical changes associated with addiction; 3. the modulation and pathological implication of 5-NT and ENT in morphine-dependence, by using neurobehavioral study, microdialysis technique, RT-PCR, confocal laser scanning microscope and western blot assay. In conclusion, the current project will address an interaction between morphine and uridine, which could extend previous studies by identification of the neuromodulator role of uridine. Investigating the targets of morphine-induced uridine release will highlight a novel viewpoint for understanding the mechanism of opioid-addiction, and will contribute to develop a new type of anti-opioid addiction drug.

截至目前，尿苷在吗啡导致的神经行为学变化中所发挥的作用尚不清楚，参与调节尿苷水平的尿苷转运体以及代谢酶是否参与了吗啡导致的神经行为学变化也未见报道。按照项目预定方案，我们采取在体微透析技术结合在体腺相关病毒介导的基因敲低技术，免疫组化以及免疫荧光等技术发现：1.外源性尿苷能够通过调节多巴胺能，谷氨酸能以及γ氨基丁酸能神经传递从而抑制吗啡导致的自主活动增加，行为敏化以及条件性位置偏爱；2.急性、慢性吗啡能够导致小鼠背侧纹状体内源性尿苷释放，其分子机制是由于吗啡能够特异性地上调小鼠背侧纹状体胞外5’核苷酸酶而非其他尿苷相关代谢酶与转运体；3.药理性抑制NT5E以及在体特异性敲低NT5E的表达能够显著抑制吗啡导致的尿苷释放以及神经行为学变化。本项目按照计划完成了预定研究内容：1.阐明了外源性给予尿苷对吗啡导致神经行为学的影响以及基于多巴胺能，谷氨酸能，γ氨基丁酸能递质释放的机制研究；2.阐明了急性、慢性给予吗啡对小鼠背侧纹状体尿苷释放的规律的研究；3.阐明了急性、慢性吗啡对小鼠背侧纹状体尿苷代谢酶与转运体表达的影响；4.阐明了药理水平抑制以及基因水平敲低胞外尿苷代谢酶NT5E对吗啡导致的尿苷释放以及神经行为学的影响。本项目进一步揭示了吗啡成瘾与尿苷之间的相互关系，同时为进一步围绕相关靶点开发新型抗吗啡成瘾药物奠定理论基础。截止目前，本项目已发表SCI收载文章2篇，在投1篇，培养研究生4名。综上，项目按照计划完成了预期的研究内容与研究目标。