Department of Pharmacology, Shenyang Pharmaceutical University, 110016, Shenyang, PR China.
Department of Pharmacology, Shenyang Pharmaceutical University, 110016, Shenyang, PR China.
Neuropharmacology. 2018 Oct;141:1-10. doi: 10.1016/j.neuropharm.2018.07.035. Epub 2018 Jul 30.
There is growing evidence that uridine may act as an endogenous neuromodulator with a potential signaling role in the central nervous system in addition to its function in pyrimidine metabolism. We previously found that acute morphine treatment significantly increased uridine release in the dorsal striatum of mice, indicating that uridine may contribute to morphine-induced neurobehavioral changes. In the present study, we analyzed the mechanism involved in morphine-induced uridine release and the role of uridine in morphine-induced neurobehavioral changes. Uridine release in the dorsal striatum of mice was assessed by in vivo microdialysis coupled with high performance liquid chromatography (HPLC) after morphine treatment. Western blotting and immunofluorescence were used to evaluate the expression of uridine-related proteins. Morphine-induced neurobehavioral changes were assessed by locomotor activity, behavioral sensitization and conditioned place preference (CPP) test. The expression of NT5E, an extracellular enzyme involved in formation of nucleosides, including uridine, was specifically knocked down in the dorsal striatum of mice using adeno-associated virus (AAV)-mediated short hairpin RNA (shRNA). The results indicated that both acute and chronic morphine administration significantly increased uridine release in the dorsal striatum, and this was associated with upregulation of NT5E but not other uridine-related proteins. Inhibition of NT5E with APCP or shRNA markedly inhibited morphine-induced uridine release in the dorsal striatum and related neurobehavioral changes, including hyperlocomotor activity, behavioral sensitization and CPP. Our data give a better understanding of the contribution of NT5E to morphine-induced uridine release and neurobehavioral changes, and identify NT5E as a potential target for treating morphine abuse.
越来越多的证据表明，尿苷除了在嘧啶代谢中发挥作用外，还可能作为一种内源性神经调质，在中枢神经系统中发挥潜在的信号作用。我们之前发现，急性吗啡处理显著增加了小鼠背侧纹状体中的尿苷释放，这表明尿苷可能有助于吗啡引起的神经行为变化。在本研究中，我们分析了吗啡诱导尿苷释放的机制以及尿苷在吗啡诱导的神经行为变化中的作用。用吗啡处理后，通过体内微透析与高效液相色谱（HPLC）结合评估小鼠背侧纹状体中的尿苷释放。用 Western blot 和免疫荧光评估与尿苷相关的蛋白表达。通过运动活性、行为敏化和条件性位置偏好（CPP）试验评估吗啡诱导的神经行为变化。使用腺相关病毒（AAV）介导的短发夹 RNA（shRNA）特异性敲低小鼠背侧纹状体中的 NT5E（一种参与包括尿苷在内的核苷形成的细胞外酶），以评估 NT5E 的表达。结果表明，急性和慢性吗啡给药均显著增加了小鼠背侧纹状体中的尿苷释放，这与 NT5E 的上调有关，但与其他尿苷相关蛋白无关。用 APCP 或 shRNA 抑制 NT5E 可显著抑制吗啡诱导的小鼠背侧纹状体中的尿苷释放和相关神经行为变化，包括过度运动活性、行为敏化和 CPP。我们的数据更好地了解了 NT5E 对吗啡诱导的尿苷释放和神经行为变化的贡献，并确定 NT5E 是治疗吗啡滥用的潜在靶点。
